JPH08101618A - Color image recorder - Google Patents

Abstract

PURPOSE: To form a color image of high quality by eliminating color slurring caused by the change of a carrying speed because of the eccentricity of a recording paper carrying roller and color irregularity caused by the irregular distribution of an image dot. CONSTITUTION: This color image recorder is constituted of the recording paper carrying roller 11 moving a recording paper back and forth, a recording means respectively performing printing and recording with different colors on the same area on the recording paper at the time when the recording paper is moved forth by the roller 11, a detecting means 103 detecting the rotation angular position of the roller 11, a storing means 105 storing the angular position of the roller 11 at the time when the recording means starts printing and recording with a first color, and controlling means 106, 107, and 110 for controlling printing and recording with the second and succeeding colors by means of the recording means to start from the angular position at the time when the roller 11 starts printing and recording with the first color.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image recording apparatus for printing color image data without color misregistration.

[0002]

2. Description of the Related Art FIG. 16 shows a schematic structure of a conventional color image recording apparatus using an electrostatic recording method.

In the drawing, reference numeral 2001 is a roll-shaped electrostatic recording paper, and reference numeral 2001 'is a long continuous recording paper fed from the electrostatic recording paper roll 2001 at the time of printing. Further, 2002 is a guide roller, 2003 is a counter electrode, and 2004 is a recording head. While the recording paper 2001 ′ fed from the electrostatic recording paper roll 2001 passes between the counter electrode 2003 and the recording head 2004, a charge corresponding to the gradation of the image is applied to the surface of the recording paper to form a latent image. It

Reference numeral 2005 denotes a four-color developing head of, for example, Y (yellow), M (magenta), C (cyan), and K (black). The developing heads 2005 are independent for each color, and each developing head is independent. Can be moved up and down and can be moved between a standby position and a developing position. The developing head that is not used for development is retracted to the standby position, and only the developing head that is used for development is moved to the developing position. At the developing position, the developing solution can be applied to the surface of the recording paper that moves on the recording paper conveyance path.

The latent image on the surface of the recording paper is thus developed by each color by being acted on by the developing solution when passing through the position of the developing head. Reference numeral 2006 denotes a suction head for sucking the developer remaining on the surface of the recording paper after development.
Is a suction roller for sucking the developing solution on the surface of the recording paper left by the suction head 2006, 2008 is a recording paper transport roller for transporting the recording paper, and 2009 is a pinch roller which is in contact with the recording paper transport roller 2008 and is in contact with the recording paper transport roller 200.
The recording sheet is sandwiched between the recording sheet 8 and the sheet 8, and the rotation of the recording sheet conveying roller 2008 is transmitted to the recording sheet to convey the recording sheet. Reference numeral 2010 denotes a cutter for cutting a recording sheet on which an image has been recorded into a required size and discharging the recording sheet.

[0006] The conventional device is roughly constructed as described above,
The recording paper 2001 ′ is attached to the recording head 2004 and the developing head 2.
By reciprocating between 005, latent image formation and development are repeated for each color to print a color image.

However, the electrostatic recording paper roll 200
1, the roller 2002, the suction roller 2007, the recording paper transport roller 2008, the pinch roller 2009, and the like, the transport speed of the recording paper is not constant due to eccentricity of the rotation system, and the latent image position on the recording head is delicate for each color. Misalignment,
The overlapping of the recording dots of each color is deviated, and color unevenness occurs.
In many cases, the rotation system that exerts a particularly large influence is the recording paper conveyance roller 2008 for paper conveyance.

For example, as shown in FIG. 17, let us consider a case where the recording paper conveying roller 2008 having a radius r1 has a rotation axis X at a position eccentric from the original center axis O by ΔL. . In this case, the maximum radial length r2 viewed from the rotation axis X is longer than the original radius r1 of the recording paper transport roller 2008 by ΔL, and the minimum radial length r3 viewed from the rotation axis X is Recording paper transport roller 20
When the recording paper conveyance roller 2008 is driven to rotate at a constant speed by ΔL from the original radius r1 of 08, the peripheral speed at the radial minimum length r3 position becomes slower, and conversely the maximum radial direction. The peripheral speed at the position of the length r2 is increased, and the feeding speed of the recording paper has a high speed portion and a low speed portion. Then, the latent image formation is performed by aligning only the image recording start position on the recording paper for each color on the assumption that the recording paper is conveyed at a constant speed.

[0009]

As a result, the image of the first color is recorded as shown in FIG. 18A, for example. In the image of FIG. 18A, d is the dot of the image, the horizontal direction of the drawing is the sub-scanning direction (recording paper feed direction (Y direction)), and the vertical direction is the main scanning direction (electrode array of the recording head). Direction is the transverse direction (X direction) of the recording paper.

In this figure, the nip point of the pinch roller 2009 with respect to the recording sheet conveying roller 2008 at the start of printing is almost the same as the point S2 of the recording sheet conveying roller 2008 (see FIG. 17B). When the position is close to the radius r1 and the original transport speed can be secured, the ideal dot d of the maximum size contacts the adjacent dot at the contour position like the position of the region d1. Although it is in a state (dot interval Δd1), the nip point with respect to the recording paper conveyance roller 2008 has a maximum radius r2 like the point S1 of the recording paper conveyance roller 2008 (see FIG. 17B). When the transport speed is close to, and the transport speed is higher than the original transport speed, the dot d of the maximum size is adjacent to the adjacent dots like the position of the area d2. Becomes larger away from the state and the door (dot interval Δd2).

Then, the nip point with respect to the recording paper carrying roller 2008 is a position close to a position having a minimum radius r3, as shown by point S3 of the recording paper carrying roller 2008 (see FIG. 17B), and originally, When the transport speed is slower than the transport speed of, the maximum size dot d partially overlaps the adjacent dot like the position of the area d3 (dot interval Δd3). .

In this state, the image of the first color is formed, and once rewound on the recording paper roll 2001 side,
The next second color image formation starts, but the influence of the eccentricity of the recording paper conveyance roller 2008 is shown in FIG.
As shown in (b) of FIG. 5, the dot shift appears with respect to the dots of the first color.

That is, the rewinding to the recording paper roll 2001 side after the image formation of the first color is performed by the recording paper conveying roller 2
008 is rotated in the reverse direction, and with the position of the recording head 2004 as a reference, the start end of the image forming area is controlled to be returned to the recording paper roll 2001 side to some extent. After that, the recording paper conveying roller 2008 is rotated in the forward direction to carry the recording paper 2001 ′ in the forward direction, and the second color image formation is started at the timing when the starting end of the image recording area reaches the position of the recording head 2004.

However, before the image recording of the second color,
When a slip occurs between the recording paper transport roller 2008 and the recording paper, the recording paper moves due to the eccentricity of the recording paper transport roller 2008 between the image formation of the first color and the image formation of the second color. The influence of the speed change on the recorded image extends to different positions in the recorded image.
The second color image will not match. When a cut sheet is used as the recording sheet, even if the above-described recording sheet 2001 ′ and the conveying roller 2008 do not slip, a recorded image with eccentricity in the first color and the second color is generated due to a conveyance error or the like. It is conceivable that the influence positions of are different.

Further, due to backlash of the driving force transmission system of the recording sheet conveying roller 2008, the actual conveyance start will be somewhat delayed, and accordingly, the recording sheet conveying roller 2 will be delayed.
It is also conceivable that the state of speed change due to the effect of eccentricity of 008 will be slightly different.

Therefore, the positions of the first-color dots and the second-color dots are displaced as shown in FIG. Due to the deviation of the dot positions, the color of the non-overlapping area is different from that of the overlapping area, and this is a slight deviation but deteriorates the image quality. Further, the fact that a dense portion and a rough portion of dots are generated due to the effect of the eccentricity of the recording paper conveyance roller 2008 means that the distributions of the densities are different. This causes unevenness, which also deteriorates the image quality.

As a measure against such a problem, for example, in Japanese Unexamined Patent Publication No. 4-131876, each color formed by four drums of cyan, magenta, yellow and black on a recording paper held and conveyed by a belt is described. In a color image recording apparatus for sequentially transferring images to obtain a color image, a technique is disclosed in which the phases of eccentricity of four drums of each color are matched with a recording area on a recording paper.

However, in the structure of the above publication, the degree of eccentricity of each drum is different, so that the positional deviation cannot be completely prevented. Further, when the drum is deformed due to pressure contact with the platen roller, the phase of the four drums coincides with each other because the drum potentially has a complicated phase together with the eccentricity of the drum. It was virtually impossible to do.

Further, in the above-mentioned publication, it is possible to roughly match the portion where the paper conveyance speed is high and the portion where the paper conveyance speed is slow among the four drums, but the recording dot distance is not constantly corrected during printing by one drum. Therefore, the distance between recording dots (the distance between lines) in the sub-scanning direction depends on the eccentricity of the recording paper conveyance roller, and if you look closely at the print screen with a single density, color unevenness occurs in the paper feeding direction. It is confirmed that it is doing.

Therefore, an object of the present invention is to eliminate the color shift due to the eccentricity of the recording paper conveying roller and the color unevenness due to the density of the image dots to form a high quality color image. An object is to provide an image recording device.

[0021]

In order to achieve the above object, the present invention has the following constitution. That is, firstly, a recording paper conveying roller for reciprocating the recording paper, and a recording means for performing printing recording of different colors in the same area on the recording paper when the recording paper is moved forward by the recording paper conveying roller. ,
Detection means for detecting the rotational angular position of the recording / conveying roller; storage means for storing the angular position of the recording paper-conveying roller at the start of printing of the first color image by the recording means;
The recording means controls the print recording of the second and subsequent colors to be started from the angular position of the recording paper conveying roller at the start of the print recording of the first color.

Secondly, a recording paper conveying roller for reciprocating the recording paper, and when the recording paper is moved forward by the recording paper conveying roller, line units of different colors are provided in the same area on the recording paper. Recording means for performing image recording, detecting means for detecting the rotational angular position of the recording and conveying roller, registration mark recording means for recording registration marks on recording paper at fixed time intervals, and reading means for reading the registration marks. Calculation means for calculating the moving speed displacement of the recording paper at each rotational angular position of the recording paper carrying roller from the read information of the registration mark, and each rotation of the recording paper carrying roller based on the calculated moving speed displacement of the recording paper carrying roller. Data creating means for creating correction data for printing recording timing of each line by the recording means at the angular position; and the data creating means Which is configured by providing a control unit for controlling the printing recording by said recording means on the basis of the correction data has been made.

Thirdly, a recording paper conveying roller for reciprocating the recording paper, and when the recording paper is moved forward by the recording paper conveying roller, printing in line units in different colors in the same area on the recording paper. Recording means for performing recording, function generating means for generating a periodic function in which one rotation of the recording / conveying roller is one cycle, and print recording timing of the line unit by the recording means is changed according to the periodic function. Based on the recording control means and the image output by changing the printing recording timing of each line by the recording control means,
A parameter setting means for changing the parameter of the periodic function is provided.

[0024]

In the case of the first configuration, first, the rotational angle position of the recording paper conveying roller is detected at the time of starting the image recording of the first color, the position is stored, and the recording paper is conveyed at the start of the image recording of the second and subsequent colors. It functions so that the rotation angle position of the roller is the same as the rotation angle position of the recording paper conveyance roller at the start of image recording of the first color.

As a result, since the rotational angle position of the recording paper conveying roller at the start of image recording is the same for each color, the periodic fluctuations of the recording paper conveying speed due to the eccentricity of the recording paper conveying roller are the same, The dot position of the image is not shifted for each color, and the image quality is improved.

In the case of the second configuration, first, a registration mark is created on the recording paper at the same timing as when the image is recorded, the registration mark is read, and the moving speed displacement of the recording paper at each rotation angle position of the recording paper conveying roller is made. And the recording timing correction data of the recording dot is created based on this.
Image recording is performed by correcting the recording timing from the time of recording the image of the first color based on the correction data.

For this reason, since the positions of the recording dots in each color are the same, the color misregistration is less noticeable, and the print images in line units within the same color image are arranged at uniform intervals in the sub-scanning direction. There is little change in density in the intermediate colors, and it is possible to make color unevenness invisible.

Further, in the case of the third configuration, in order to eliminate the recording dot position deviation of the image recording by the recording paper conveying roller having an eccentricity, the print recording timing in line unit is adjusted according to the eccentricity of the recording paper conveying roller. to correct.

Here, since the paper carrying speed due to the eccentricity of the recording paper carrying roller changes in a periodic function form with one rotation of the recording paper carry roller as a cycle, the recording dot position deviation also becomes a periodic function form. Therefore, the correction data is also the periodic function timing correction data. Further, the correction amount is made variable, and the parameter setting means is provided so that the phase of the paper transport speed characteristic due to the eccentricity of the recording paper transport roller and the phase of the generated periodic function can be matched. Based on the correction data, the printing recording timing for each line is corrected from the time of recording the image of the first color so that the image can be recorded.

For this reason, since the recording dot positions of the respective colors coincide with each other, the color misregistration is less noticeable, and the print images of the line unit in the same color image are arranged at equal intervals in the sub-scanning direction, and the intermediate color There is little change in density, and it is possible to make color unevenness invisible. Further, the provision of the parameter setting means simplifies the apparatus and improves the productivity.

Incidentally, in order to make it difficult to see the color unevenness due to the recording dot position deviation of the image recording by the recording paper conveying roller having an eccentricity, a common density change is given for each printing line during each color recording. You can also In the density correction data creation, since the paper transport speed due to the eccentricity of the recording paper transport roller changes like a periodic function, the deviation of the recording dot position also becomes like a periodic function. And the position of the generated periodic function is matched with the phase of the paper transport speed characteristic due to the eccentricity of the recording paper transport roller by allowing the parameter setting means to change the magnitude of the correction amount. Act to be able to. Then, based on the correction data thus obtained, the recording density can be corrected and the image can be recorded from the time of recording the image of the first color.

In this way, since the color recording dot positions coincide with each other, the color misregistration is less noticeable, and the density correction for each line is low in the area where the lines are dense and the density is low in the area where the lines are rough. By high modulation, the density variation between lines in the same color image is small, and it is possible to make color unevenness and the like invisible.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a schematic block diagram of an electrostatic color recording apparatus to which the present invention is applied, and FIG. 2 shows a control block.

In FIG. 1, reference numeral 1 is an electrostatic recording paper roll, which is formed by winding an electrostatic recording paper (recording sheet) 2 as a recording medium around the outer circumference of a paper tube. In addition, since the electrostatic recording type color recording apparatus is taken as an example in the present embodiment,
The material of the recording paper here may be pulp paper, or may be a plastic film sheet or the like,
Further, chemically synthesized paper or paper obtained by combining these materials may be used, but the point is that recording is possible and no expansion and contraction is preferable. Here, there are various recording methods such as an electrophotographic method, an inkjet method, and a thermal transfer method, and an application example to an electrostatic recording method is described as an example. Note that it is applicable to.

This electrostatic color recording apparatus includes the recording paper 2 described above.
A guide roller 3 is arranged near the setting position of the recording sheet, and a recording paper conveying roller (driving roller) 11 is arranged downstream of the roller 3. Furthermore, a guide roller 18 is provided downstream of the recording paper conveyance roller 11, and a take-up roller 31 is further provided downstream thereof, and the end portion of the recording paper 2 passes through the roller 3 and the recording paper conveyance roller. You are led to 11.

A recording system and a developing system are installed between the roller 3 and the recording paper conveying roller 11, and a recording paper winding system and a cutting system are arranged downstream of the recording paper conveying roller 11. Reference numeral 5 denotes an electrostatic recording head such as an ion head or a multi-stylus that constitutes a recording system, and forms an electrostatic latent image on the recording paper 2 that moves in contact with the end surface of the recording head.

Reference numeral 4 is an optical mark reading head, and this mark reading head 4 is arranged in the vicinity of the guide roller 3 and on the downstream side. The mark reading head 4 is a registration mark 4 for recording position control, which will be described later, recorded on the recording paper 2.
0 and the edge of the recording paper 2 are read together. For example, a CCD (charge coupled device) linear
An image sensor (solid-state line image sensor) is used. This image sensor has a one-dimensional position resolution, and therefore, it is possible to identify the position and the width of the mark on the recording paper from the output signal of the image sensor.

The control unit 110 controls the mark reading head 4
Based on the output of the above, the registration mark 40 for controlling the recording position is obtained together with the information of the edges 41 and 42 of the paper, and the paper feeding and the recording start timing are controlled.

The developing heads 6 to 9 constitute a developing system, and the developing heads 6 to 9 are supplied with liquid developers of different colors to form the electrostatic latent image on the recording paper. Develop with liquid developer. In this example, four developing heads are arranged side by side. These developing heads 6 to 9 sequentially perform an ascending / descending operation in synchronization with each reciprocating operation when a color image is formed while reciprocating the recording paper 2 a plurality of times, as described later, to obtain a predetermined color image. When one developing head is in contact with the recording paper 2, the other developing heads are retracted from the recording paper 2 and the developing is performed one color at a time. is there.

Reference numeral 10 denotes a developing solution sucking roller which is installed downstream of the group of developing heads 6 to 9 and upstream of the recording sheet conveying roller 11, and which is used for recording sheet 2 at the time of development by the developing head. It is for absorbing and removing the excess developer adhering to the top.

A pressing roller 12 is disposed in pressure contact with the peripheral surface of the recording paper conveying roller 11, and the recording paper conveying roller 11 holds the recording paper 2 in cooperation with the pressing roller 12. The recording paper 2 can be fed by rotating the recording paper conveyance roller 11. Further, a guide plate 13 curved in an arc shape is attached to the recording paper conveyance roller 11, and by feeding the leading end of the recording paper 2 between the recording paper conveyance roller 11 and the guide plate 13, the pressing roller is pressed. 12 and recording paper conveyance roller 11
The recording paper 2 can be held between and.

The pressing roller 12 is constructed so that the pressure contact with the recording paper conveying roller 11 can be released by a driving means (not shown) controlled by the controller 110.

A guide roller 17 which is paired with the guide roller 18 is arranged on the guide roller 18. A pair of recording paper leading guide plates 14 are arranged on the exit side of the recording paper conveying rollers 11, and a pair of guide plates are formed on the upstream side of the recording paper conveying rollers 11 so as to be opened between the guide rollers 18 and 17. 23 is arranged, and the recording paper 2 sent out from the recording paper conveying roller 11 is sent out from the recording paper lead-out guide plate 14 to the guide plate 23, and is guided between them and between the guide rollers 18 and 17. It is supposed to be guided.

Reference numeral 15 is a Y cutter for cutting the recording paper in a direction orthogonal to the recording paper feeding direction, and 16 is an X cutter for cutting the recording paper in a direction parallel to the recording paper feeding direction.

Reference numeral 26 denotes a recording paper path switching guide lever, the base end of which is rotatably supported by a pin 27. The recording paper path switching guide lever 26 guides the leading end of the recording paper 2 pinched and sent by the guide rollers 18 and 17 toward the automatic sheet winding device 30, or in the direction of the Y cutter 15 and the X cutter 16. It is for guiding or switching to.

When the recording paper path switching guide lever 26 guides the recording paper 2 to the Y cutter 15 and the X cutter 16, it guides the guided recording paper 2 to the Y cutter 15 and the X cutter 16. The rollers 19 and 20 and the guide plate 24 are arranged, and further the Y cutter 1
5, a guide plate 25 and a pair of guide rollers 2 for sending the recording paper 2 cut by the X cutter 16 to the outside.
1, 22 are arranged.

The automatic recording paper winding device 30 has a winding roller 31, a pressure contact roller 33 having a peripheral surface in contact with the winding roller 31, and the recording paper 2 guided and fed by the guide lever 26 on the peripheral surface of the winding roller 31. Guide along and press roller 3
3 and a guide plate 32 which is guided between the guide plates 32 and 3. The recording paper 2 guided and guided by the guide lever 26 can be automatically wound around the winding roller 31.

The guide roller 3, the take-up roller 31, the recording paper conveying roller 11, and the guide rollers 18 and 17 are rotated in the forward direction when the recording paper 2 is sent for recording or the like. In order to apply tension to the recording paper 2, the roll 1 slowly rotates forward with an appropriate force or applies a moment of reverse rotation. In the case of rewinding, the electrostatic recording paper roll 1 is rotated in the reverse direction, and the guiding roller 3, the winding roller 31, the recording paper conveying roller 11, and the guide rollers 18 and 17 apply tension to the recording paper 2. To
Slowly reverse the rotation with an appropriate force, or give a forward rotation moment.

FIG. 2 is a block diagram showing the configuration of the control system applied to the first embodiment.

In FIG. 2, reference numeral 11 is a recording paper carrying roller (driving roller), 102 is a drive motor for driving the recording paper carrying roller 11, and 103 is a structure for transmitting a direct connection or a rotation to the rotary shaft of the recording paper carrying roller 11. The rotary encoder, which outputs a pulse in accordance with the rotation, functions as a detection unit that detects the rotational angle position of the recording paper conveyance roller 11. 104 is the drive motor 10
2 is a drive circuit for driving and controlling 2.

Reference numeral 105 is a counter section for counting the pulses from the rotary encoder 103, and 106 is a buffer, which stores a counter value corresponding to the rotational angle position of the recording paper conveying roller 11. Reference numeral 107 denotes a comparison unit for comparing the data value of the counter unit 105 and the buffer value of the buffer 106, and when the values match, that is, the rotation position of the recording paper conveyance roller 11 becomes a certain angular position. At that moment, a signal is transferred to the control unit 110 to inform it.

Reference numeral 108 denotes a head control unit, which controls a host unit (host computer or the like) (not shown) from the control unit 110.
Is a head control unit that drives and controls the electrostatic recording head 5 based on image data and a recording control signal provided via the control unit to form a latent image corresponding to the image data. An output signal from the head controller 108 is given to the electrostatic recording head 5, so that the electrostatic recording head 5 forms a latent image on the recording paper.

Although the electrostatic recording head 5 is assumed to be an electrostatic recording type recording head here, there are various recording systems such as an ink jet system, an electrophotographic system, a thermal transfer system, and other such systems. In this case, naturally, the present invention can be applied.

Reference numeral 110 denotes a control unit for controlling the entire system, which realizes various control functions necessary for realizing the functions of the color image recording apparatus by software control, and includes an MPU (microprocessor) and a memory. Etc.

The control section 110 generates a line recording timing signal ts at a constant time interval and supplies it to the head control section 108 so that the head control section 108 receives the line recording timing signal ts at the timing of the main scanning direction. In this configuration, the electrostatic recording head 5 is driven and controlled so as to form the line image.

In addition to the above, the printer has various drive control systems such as path switching and cutter drive control system, which are not directly related to the present invention and will not be described here.

The electrostatic color recording apparatus having the above structure operates as follows. First, the basic operation will be described. First, prior to the start of recording, the recording paper 2 is pulled out from the recording paper roll 1, and the leading end of the recording paper 2 is set between the feed roller 11 and the pressure contact roller 12 and the guide rollers 17 and 18. The recording paper path switching guide lever 26 is set to a position that guides the leading end of the recording paper 2 toward the automatic sheet winding device.

In such a set state, for forming a registration mark for controlling the recording position and forming a color image of the first color (when the black image is printed first), or for controlling the recording position. The recording paper 2 is fed in the right-hand direction (forward direction) in FIG. 1 to form a registration mark for printing (in the case of a method of printing in the order of Y, M, C, K). Then, in order to form the first color image (in the case of the former method) or to form only the registration mark (in the latter case), the electrostatic recording head 5 transfers the first color image onto the recording paper 2. An electrostatic latent image of an image is formed, and at the same time, an electrostatic latent image for forming a registration mark 40 for recording position control as shown in FIG. 3 is formed on one side of the recording paper 2 (edge 41 in the example of FIG. 2). Side) (for the former method). In the latter case, an electrostatic latent image for forming only the registration mark is formed on one side of the recording paper 2 (edge 41 side in the example of FIG. 2).

A toner image is obtained by developing these electrostatic latent images with the developing head for the corresponding color of the first color in the former method and with the developing head for black in the latter method. Thus, in the former method, the first color image and the registration mark 40 for recording position control are recorded on the recording paper 2, and in the latter method, only the registration mark 40 is recorded on the recording paper 2.

The registration mark 40 for controlling the recording position
Is to detect the position of the recording paper 2 in the transport direction and correct the electrostatic latent image formation start position of each image of the second and subsequent colors.
These corrections are performed by the control unit 110 described above.

Next, in this apparatus, the angular position of the recording paper transport roller at the start of printing the first color and the angular position of the recording paper transport roller 11 at the start of printing the second and subsequent colors are equalized. explain.

When the registration mark is formed at the same time as the printing and recording of the first color, the control unit 110 resets the count value of the counter unit 105 at the same time as the start of printing and sets the comparison reference value "0" in the buffer 106. . Also, the first
The recording paper is conveyed in the forward direction while being detected by the registration mark reading head 4 prior to the recording of the image of the color, and when the registration mark start position on the recording paper has just reached the position of the registration mark reading head 4, the control unit 11
0 resets the count value of the counter unit 105 and sets the comparison reference value “0” in the buffer 106.

By this operation, in any of the recording methods, the rotational angle position of the recording paper conveying roller 11 when the registration mark start position on the recording paper reaches the position of the registration mark reading head 4 is "". It is stored as the 0 "position.

After that, after the registration mark position on the recording paper reaches a position past the electrostatic recording head 5, the image recording is started. In this case, the control pulse number of the drive motor 102 that conveys the recording paper is set in advance for the distance from the registration mark reading head 4 to the electrostatic recording head 5, and the control unit 110 sets the count value corresponding to the pulse number. When it counts, print recording starts.

When the recording of the first color image is completed,
The control unit 110 includes a paper core roller and a recording paper conveyance roller 11
To rewind the recording paper in the reverse direction. The control unit 110
When the recording paper is rewound, the counter unit 105 is decremented and counted, and when the recording paper is fed out, the counter unit 105 is controlled to be incremented and counted.

At the start of the next printing of the second color, the control section 110 sets the registration mark 40 on the recording paper formed at the same time as the printing of the first color or prior to the printing.
While being detected by the optical mark reading head 4, the recording paper is fed in the forward direction by driving the recording paper conveyance roller 11.

Then, when the registration mark start position on the recording paper has just reached the position of the registration mark reading head 4, the count value of the counter section 105 is compared with the reference value "0" of the buffer 106 to make it equal. If so, the line image recording signal is sent to the head control unit 108 so that the printing recording of the second color is started as it is.

On the other hand, when the registration mark start position on the recording paper detected by the registration mark 40 just reaches the position of the registration mark reading head 4, the count value of the counter unit 105 becomes the reference value “0” of the buffer 106. If not, the control unit 110 temporarily stops the conveyance of the recording paper, and releases the pressure contact of the pressing roller 12 to the recording conveyance roller 11 in a state where the leading ends of the recording paper are nipped by the guide rollers 17 and 18. Then, in this state, the recording paper conveyance roller 11 is idled in the normal rotation or the reverse rotation, and when the count value of the counter 105 reaches “0”, the idle rotation is stopped, and the pressing roller 12 is moved to the recording paper conveyance roller 11 again. Press it.

By this operation, the angular position of the recording paper conveying roller when the registration mark start position on the recording paper reaches the position of the registration mark reading head 4 is set to the first position.
It can be set to the same "0" position as the angular position of the color.

After the adjustment of the angular position of the recording paper conveying roller 11 as described above, the recording paper is conveyed, and the registration mark position on the recording paper passes the electrostatic recording head 5 like the first color. The control unit 110 controls to start printing, sends the print data to the head control unit 108, and prints the second color.

The recording paper 2 is taken up by the take-up roller 31, the guide plate 32, and the pressure contact roller 33 of the automatic recording paper take-up device 30 except during the last color printing operation.
It is wound around the outer circumference of 1 and sent.

At the time of recording the last color, the recording paper path switching guide lever 26 is switched to the direction in which the recording paper 2 is discharged to the outside of the apparatus, the recording paper 2 is fed again, and the Y cutter 15, By operating each of the X cutters 16, the recorded recording paper 2 is cut into a desired size and discharged to the outside of the apparatus.

The above is because of the eccentricity of the recording paper conveying roller,
Color misregistration caused by a change in recording paper conveyance speed is eliminated by controlling the timing so that the rotation angle position of the recording paper conveyance roller is made to coincide with each other during printing of any color, thereby preventing a change in hue. It was a thing,
Since the dot formation timing is not controlled with respect to changes in the recording paper conveyance speed, adjacent dots are widened in areas where the conveyance speed is high, and adjacent dots overlap in areas where the conveyance speed is low, so that recording is performed in a dense and dense state. . Therefore, there is a concern that the concentration may change. An example for improving this will be described as a second example.

(Second Embodiment) In this embodiment, the recording timing in the sub-scanning direction (recording paper conveyance direction) is controlled so that the dots (line images) are arranged at equal intervals in the sub-scanning direction. The image quality is improved by controlling the above, and the details will be described below.

FIG. 6 is a block diagram showing the second embodiment of the present invention. In the figure, 11 is a recording paper conveying roller,
Reference numeral 102 denotes a drive motor that drives the recording paper conveyance roller 11.
A rotation detector 201 is directly connected to the rotation axis of the recording paper conveyance roller 11 or configured to transmit rotation. The rotation detector 201 detects a constant angle position for one rotation.

The rotation detector 201 is constructed, for example, as follows. That is, a disc that interlocks with the rotation of the recording paper conveyance roller 11 is provided, and a position marker hole is provided in a part of this disc. Further, the light source and the light receiving element are arranged so as to face each other through the disc. The photo coupler described above is provided at a fixed position, and the position of the position marker hole is detected by transmission of light by the photo coupler. Of course, the present invention is not limited to this, and as long as it can detect when a specific angular position in one rotation of the roller 11 is reached, a structure in which a magnet is provided on the disk and the rotation is detected by a magnetic sensor, It is possible to use various currently known position detecting means, such as a configuration in which a protrusion is provided on a disk and a micro switch provided at a fixed position is differentially operated to detect arrival at the specific angular position.

Reference numeral 104 is a drive circuit for controlling the drive motor 102, 202 is a timing correction unit for controlling the dot recording timing of the recording head 5, and 203 is the correction amount from the correction data unit 204 to the recording paper conveying roller 11. An address control unit for extracting timing correction amount data corresponding to rotation.

The correction data section 204 is the recording sheet conveying roller 1.
Despite the fluctuation of the recording paper transport speed due to the eccentricity of 1,
6 is a timing correction data table that changes the dot recording timing of the recording head 5 so that the dot recording positions in the sub-scanning direction are aligned on the recording paper 2. The 108 head controller and 5 are recording heads, and the head controller 108 and the recording head 5 are the same as those in the first embodiment. A control unit 110A controls necessary control of the entire system.

Further, 206 is a marker position detector for optically reading a marker recorded on one side of the recording paper 1 at a rate of one line for n dots, and the sensor unit is a line sensor, and 207 The sensor drive unit indicated by (1) moves one end of the recording paper in the sub-scanning direction at a constant speed.

Such an operation of the marker position detector 206 by the sensor driving unit 207 is performed when the recording paper conveyance roller 11 is stationary. It does not matter if it is outside this system. Further, the sensor driving unit 207 is the control unit 11
With 0, the above control is performed. Marker position detector 206
The output signal of is transferred to the calculation unit 208. Computing unit 208
Is a calculation unit that calculates the line position of the registration mark, which is a position marker on the recording paper, based on the signal. 209
Is a position shift amount calculation unit, and based on the line position information from the calculation unit 208, the marker position (registration mark position) and the respective marker positions (registration mark position) with respect to the rotation angle during the virtual constant speed conveyance of the recording paper. ) Is a position shift amount calculation unit that calculates a shift amount from

Reference numeral 210 denotes a correction data table preparation section for calculating the correction amount of the dot recording timing of the recording head with respect to the rotational angle position of the recording paper conveying roller from the positional deviation amount. The data created by the correction data table creation unit 210 is transferred to the correction data unit 204 of the color image recording apparatus.

In this embodiment, the recording paper conveying roller 11 is driven to rotate, and while the recording paper is being conveyed, the recording head 5 forms latent images of registration marks at equal time intervals, and the developing head develops and outputs. The sample print is measured by the measurement system for generating correction data, the speed variation unevenness due to the eccentricity of the recording paper conveyance roller 11 is measured, and the latent image formation timing in dot units is adjusted according to the speed variation unevenness. A conversion table is obtained and set in the correction data section 204 of the color image forming apparatus. Then, in the color image recording apparatus, when the image is recorded, the correction data unit 20 sets the latent image formation timing in line units in the sub-scanning direction.
This is a method of controlling the latent image forming timing of the recording head 5 by adjusting according to the table of No. 4 and correcting by the timing correction unit 202 so that the interval between adjacent dots becomes a constant pitch.

Therefore, the correction data generating measuring system may be built in the color image recording apparatus as shown in FIG. 6, or may be independent from the color image recording apparatus as shown in FIG. It may be configured as a device.

Next, the operation will be described.

The correction data creation will be described first. In this apparatus, the recording paper is first conveyed to record the registration mark. The registration mark is recorded on one edge of the recording paper at a rate of one line for n dots. At that time, the recording paper is carried by the recording paper carrying roller 11, and the recording paper carrying roller 11 is driven by the drive motor 102. Drive motor 102
The operation is started when a command signal is transferred from the control unit 110A to the drive circuit 104, and is recorded at a constant speed under the control of the drive circuit 104.

The recording start timing in this case is different from that in the first embodiment. That is, when the disk marker hole of the rotation detector 201 that rotates in accordance with the rotation of the recording paper conveyance roller 11 passes through the photocoupler position,
Transfers the detected pulse to the timing correction unit 202,
The timing correction unit 202 starts outputting a recording timing control signal to the head control unit 108 in the mode of "no recording timing correction".

In other words, the control section 110A generates the dot recording timing signal t _s at a constant time interval in order to obtain the dot interval for obtaining the dot density corresponding to the resolution during image formation (printing), and the timing correction section 202. Then, the dot recording timing signal t is supplied to the head control unit 108 after the necessary correction is applied to the head control unit 108.
_The electrostatic recording head 5 is driven and controlled to form dots in the sub-scanning direction (recording paper conveyance direction) of the image at the timing of _s , but in the mode of “without recording timing correction”, the recording timing signal t _s To the head control unit 108 from the timing correction unit 202 without any correction.
Will be given to.

The head control unit 108 receives the uncorrected recording timing signal supplied from the timing correction unit 202 and the registration mark image data signal from the control unit 110A.
Then, the head control unit 108 controls the recording head 5 so that the recording head 5 forms dots corresponding to the image data of the registration mark at the timing of the recording timing signal. In addition, the output control of the image data is performed so that the registration mark is recorded with the length of one rotation of the recording paper conveyance roller.

As a result, a latent image corresponding to the image data is formed on the recording sheet by the recording head 5, and thereafter, a latent image is developed by a developing head (not shown) to print a registration mark.

The registration mark thus obtained on the recording paper is formed by ignoring the transport speed. On the other hand, the recording paper conveyance roller 11 has a slight eccentricity. Due to this, the recording paper transport speed is not constant,
Since it fluctuates with periodicity, the registration mark interval is not uniform. The registration mark on the recording paper has a positional deviation characteristic peculiar to this recording apparatus.

Further, since the recording start position of the registration mark on the recording paper and the rotation angle position of the recording paper conveyance roller at the time of recording start can be known, there is information corresponding to the registration mark and the rotation angle position of the recording paper conveyance roller.

Therefore, next, a process for obtaining data for correcting this is performed. This is because the marker portion (registration mark portion) on the recording sheet is moved to the marker position detector 206 while the recording sheet conveying roller 11 is kept stationary.
By scanning with 7, read at a constant speed,
Measure the pitch of the registration mark. The registration mark pitch may be measured by a video camera or the like and obtained from the obtained image data by image processing.

When the detection signal thus obtained is given to the line position calculation unit 208, the line position calculation unit 208 calculates the mark start line position coordinates for each marker-number based on this. As a result, the characteristic shown in FIG. 8A is obtained.

As can be seen from this figure, if the recording paper is fed at a constant speed, it is possible to obtain a straight line characteristic as shown by a constant line A in FIG. Since the conveyance speed of the recording paper is not constant due to the eccentricity of the recording paper conveyance roller 11 or the like, a curve B is drawn. If the recording paper conveyance speed is constant, the distance between marks has a constant value, but since it fluctuates due to eccentricity, the fluctuation amount is obtained and the dot recording timing is corrected. That is, the transport speed changes with a periodic wave that changes abruptly with one rotation as one cycle. The curve is drawn in this way.

The difference between the constant line A and the characteristic B is the positional deviation at each mark position.

The data of the characteristic curve obtained by the line position calculation unit 208 is transferred to the next position shift amount calculation unit 209. Then, the position shift amount calculation unit 209 calculates the position shift amount for each mark location. Since the recording paper conveyance roller 11 is rotating at a constant speed, and the mark position and the rotation angle position linearly correspond to each other, the positional deviation amount with respect to the rotation angle of the recording paper conveyance roller 11 is calculated based on this. The calculation here is a so-called trend removal process in which the linear slope is subtracted from the curve characteristics, and the difference between the dot recording position when it is assumed that the recording paper is fed at a constant speed and the actually recorded dot position is calculated. You are asking for it.

By this calculation, the positional deviation amount Δd-rotation angle characteristic as shown in FIG. 8B can be obtained. This characteristic information is transferred to the next correction data table creation unit 210. The dot recording timing of the recording head 5 is corrected according to this characteristic. In other words, when the recording paper conveyance speed is fast, the dot recording timing is correspondingly advanced, and when the conveyance speed is low, the dot recording timing is correspondingly delayed, so that the dot recording timing is correspondingly delayed.

Therefore, the correction data table creating section 210
First, based on the characteristics of the positional deviation amount Δt, the amount of variation in the distance between the marks, that is, the variation amount Δd ′ between the individual marks is calculated. This calculation is a difference process for the distance between the individual points on the curve characteristic. FIG. 8C shows the calculation result of the inter-mark distance variation amount Δd ′ at the rotation angle of the recording paper conveyance roller 11 by this calculation. A timing amount to be corrected (timing correction amount) is obtained based on this characteristic.

The timing correction amount is obtained as follows. The number of dots constituting the sub-scanning direction between a certain marker start line and the next marker start line is several tens of dots (for example, about 40 dots), and this is set as n dots, and the registration mark is set at a constant paper conveyance speed. If the distance between adjacent marker start lines on the assumption that recording is performed is d and the dot distance is ds, there is a relationship of d = nd _s .

Further, the dot recording timing in the sub-scanning direction (time from dot recording to next dot recording)
When t _s as a reference timing, printing time between each other marker start line next becomes nt _s. Therefore, in order to absorb the distance of Δd ′ temporally when d is displaced by Δd ′, the following relationship is established.
It is necessary to add dot output timing correction for t.

That is, the timing correction amount Δt is d + Δd ′: d = nt _s : n (t _s + Δt) From this, Δt = − (Δd ′ / (d + Δd ′)) × t _s , so Δt is obtained. When the correction data table is created by performing such calculation, it becomes as shown in FIG.

The timing correction amount Δt thus obtained is used to correct the print timing (recording timing) for each dot row position in the sub-scanning direction, so that the dots between dots are printed at the time of printing. As shown in FIG. 9, it is possible to perform dot recording in which the recording timing is controlled to ts + Δt.

The data Δt for each rotational angle position on the recording paper conveying roller 11 is obtained by the correction data table creating section 210 and transferred to the correction data section 204.
It is saved as table data in the correction data unit 204. As a result, the data for correcting the print timing corresponding to the periodical conveyance speed fluctuation due to the eccentricity of the recording paper conveyance roller 11 can be set, and thereafter, the recording timing is corrected by using this data. You will be able to do it.

Next, the correction of the recording timing using this data will be described. An example will be described in which the step of printing the registration mark is first performed and then the first color, the second color, ... Are printed in that order.

It is assumed that the printing of the registration mark is finished and the image recording of the first color is started. When recording the image of the first color, first, the recording paper is conveyed by the recording paper conveyance roller 11, and the recording paper conveyance roller 11 is driven by the drive motor 102. The drive motor 102 starts operating when a command signal is transferred from the control unit 110A to the drive circuit 104, and the recording paper is advanced at a constant speed under the control of the drive circuit of the drive circuit 104.

As described above, when the disk of the rotation detector 201 rotates in accordance with the rotation of the recording paper conveyance roller 11, and the rotation of the disk causes the position marker hole of the disk to pass through the photocoupler position, the rotation detector 201 becomes A pulse is generated and sent to the timing correction unit 202 and the control unit 110A.

Upon receiving the signal, the control section 110A outputs the reference recording timing signal t _s to the timing correction section 202 so that the recording head 5 starts the recording operation. The dot recording timing signal t _s from the control unit 110A is a signal for advancing printing in dot one line units, and is a signal generated at constant time intervals according to the dot density to be obtained.

In the timing correction unit 202, the rotation detector 2
From this point, the control unit 1 is triggered by the pulse from 01.
Every time the dot recording timing signal t _s from 10A is generated, the address control unit 203 is instructed to advance the address. In the timing correction unit 202, the address control unit 203 is reset when the pulse from the rotation detector 201 is received, so that the address control unit 203 is in a state where the address can be advanced from the reference address, and thereafter, the dot recording timing signal t _s. The address will be advanced each time.

The address generated from the address control unit 203 is given to the correction data unit 204, and the table data Δt of the correction data unit 204 is read in correspondence with this address. Thus, the table data Δt of the correction data unit 204
Is read in correspondence with the address instructed by the address control unit 203, so that the correction data corresponding to the rotation angle of the recording paper conveyance roller can be obtained.

This correction data is the timing correction unit 202.
Is taken into. When the timing correction unit 202 reads this correction data, it performs addition processing to shift the timing by the data value and sends a signal to the head control unit 108 at the obtained timing. When the head control unit 108 receives this signal, the head control unit 108 drives and controls the recording head 5 to form a dot row corresponding to the image data given from the control unit 110A, and the recording head 5 forms the dots of the image data on the recording paper. Form a corresponding latent image.

As a result, the dot recording timing is as shown in FIG.
The recording process of the image data is performed by the recording head 5 so that the recording is performed in such a relationship.

When the recording of the first color image is completed, the take-up drive motor (not shown) is driven and controlled by the controller 110A so as to rewind the recording paper. The winding length is a preset length, which slightly exceeds the conveyed length after the start of recording.

In the recording of the second color, when the position marker of the rotation detector 201 passes through the photocoupler position in accordance with the rotation of the recording paper conveying roller, the timing correction unit 202 and the control unit 205 record the start pulse as described above. Transfer and first
Image recording is started in a sequence like a color. This operation is similarly performed from the second color onward until the image recording of the fourth color.

As a result of such control, as shown in FIG. 10 (b), the intervals of the printed dots are constant, and as shown in FIG. 10 (a), it is affected by speed unevenness due to eccentricity. The dots are printed with a feeling that the dots are lined up at substantially equal intervals, which are much cleaner than the dots formed in the first embodiment. In this way, the inter-dot distance is made the same, and the inter-dot distance is also made the same.

In the second embodiment, the rotation detector 201
By using the pulse signal from, the control mode is adopted in which recording is always started from the same rotation angle position of the recording paper conveyance roller. However, as in the first embodiment, the angular position of the recording paper conveyance roller at the start of printing of the first color is stored, and printing is started from that angular position when printing the second and subsequent colors. Can be changed and controlled.

Further, a registration mark for detecting the image recording position may be formed on the edge of the recording paper, and this may be read by a sensor to obtain the recording start timing of each color image. That is, since the fluctuation of the peripheral speed due to the eccentricity from the recording paper conveyance is corrected by the correction table, the printing start position can be determined irrespective of the angular position of the recording paper conveyance roller.

Therefore, according to this method, even when the recording paper expands or contracts, the expansion / contraction of the recording paper can be corrected separately from the eccentricity correction.

In the above, the registration mark is recorded on the recording paper at a constant time interval, the pitch of the recorded registration mark is measured, and the latent image forming timing of the recording head is adjusted according to the pitch. The change in the conveyance speed of the recording paper due to the eccentricity of the recording paper conveyance roller is absorbed by the timing control of the latent image formation so that the dot interval becomes constant.

In this case, the recording of the registration mark and the actual measurement of the pitch must be performed for each color image recording apparatus.
It can be corrected accurately, but the process is complicated. The control for absorbing the change in the conveyance speed of the recording paper by the timing control for forming the latent image can be more easily performed without imposing such a burden.

Therefore, this example will be described below as the third embodiment.

(Third Embodiment) In this embodiment, by controlling the recording timing in the sub-scanning direction in the dot formation of the print image, the dots are arrayed in the sub-scanning direction at equal intervals. Therefore, the image quality is improved and the adjustment is simplified. The details will be described below.

FIG. 11 is a block diagram showing the structure of the third embodiment. In the figure, 11 is a recording paper conveying roller, and 102 is a drive motor for driving the recording paper conveying roller 11. Further, the rotation detector 201 is a rotation detector which is directly connected to the rotation shaft of the recording paper conveyance roller 11 or is configured to transmit the rotation and capable of detecting a constant angle position for one rotation. That is, the rotation detector 201 is the recording paper transport roller 11
Is a detector that outputs a pulse signal at a predetermined rotation angle position during one rotation of.

The structure of the rotation detector 201 may be the same as that of the second embodiment, which has already been described, so the description of the structure will be omitted here.

Reference numeral 104 denotes a drive circuit for driving and controlling the drive motor 102 in response to a command from the control unit 110B.
Is a timing correction unit. This timing correction unit 70
Reference numeral 1 denotes a control unit for correcting the dot recording timing of the recording head 5, and a controller 11 for forming an image.
The data generation control unit 7 receives the dot recording timing signal t _s output by 0B and the pulse signal of the rotation detector 201.
02 at the same time as obtaining the correction amount information from the time amount product calculating unit 705 and controlling the dot recording timing signal t _s to shift the time by the correction amount to the head control unit 108 to perform the print operation. It is for generating a command for implementation.

Reference numeral 702 is a data generation control unit, 703 is a phase amount setting unit, 704 is a sinusoidal time data generation unit,
Of these, the sinusoidal time data generation unit 704 is for generating timing correction data corresponding to the fluctuation of the recording paper conveyance speed due to the eccentricity of the recording paper conveyance roller 11. The fluctuation of the recording paper carrying speed due to the eccentricity of the recording paper carrying roller 11 causes a rotational movement of the recording paper carrying roller 11, so that it exhibits a periodic function-like change, particularly a sinusoidal change.
Time data corresponding to the change can be generated.
The sinusoidal time data generation unit 704 is configured by, for example, a data table in which a timing correction amount corresponding to a change in the conveyance speed is written for one cycle of fluctuation of the recording paper conveyance speed due to eccentricity of the recording paper conveyance roller 11. Therefore, it can be configured by a memory having such a table.

The phase amount setting unit 703 is used for the recording paper carrying roller 1.
This is for setting the phase amount B of the sinusoidal timing correction characteristic corresponding to the phase of the recording paper conveyance speed change characteristic due to the eccentricity of 1. This is performed by digital setting, and the phase amount B in the phase amount setting unit 703 can be set arbitrarily.

Further, the data generation control unit 702 shifts the phase of the sinusoidal time data by the phase required to shift the phase of the sinusoidal time data so as to match the situation of the change in the transport speed of the recording paper transport roller 11. It is an element that specifies the position of the time data, and outputs the data of this specified position in the sinusoidal time data.

That is, the data generation control section 702 is for controlling data generation for taking out the timing correction amount data corresponding to the rotational position of the recording paper conveyance roller 11 from the sinusoidal time data generation section 704. Therefore, when the sinusoidal time data generation unit 704 is configured by a memory that holds a data table, the data generation control unit 702 can be configured by a functional element that generates address data that specifies the data position of this data table,
For example, the pulse output of the rotation detector 201 and the control unit 110B generate the current position for one cycle of the fluctuation of the recording paper conveyance speed due to the eccentricity of the recording paper conveyance roller 11 with the timing correction amount corresponding to the change of the conveyance speed. This can be realized by a configuration in which, by knowing the dot recording timing signal t _s and the phase amount B, an address corresponding to the position is generated to specify the data position of the data table.

Reference numeral 705 denotes a time amount product unit for varying the correction timing amount, 706 is a time amount constant setting unit for setting the time amount to an arbitrary size A, and the timing correction amount value is inputted to 701. It The time amount multiplication unit 705 multiplies the value output from the sinusoidal time data generation unit 704 by the value set in the time amount constant setting unit 706 to obtain the correction amount information for timing adjustment as the timing correction unit 70.
The timing correction unit 701 obtains this correction amount, shifts the dot recording timing signal t _s by the correction amount, and then issues a command to the head control unit 108 to execute the print operation. This is the configuration that occurs.

The head controller 108 and the recording head 5 are the first
It is similar to the embodiment. The control unit 110B controls the center of control of the entire system.

Next, the operation will be described.

Explaining the generation of the timing correction data, the sinusoidal time data generator 704 generates the sinusoidal data as shown in FIG. 12 which is the basis of the correction value. The sinusoidal time data generation unit 704 has a signal generation circuit using a ROM, and the reference timing clock t
By reading this ROM while synchronizing with _s ,
Can be generated. The phase control of the sine wave data generation is performed by the data generation control unit 702. The period φ of the sine wave is the time for which the recording paper conveyance roller 11 makes one rotation. Further, the phase constant B of the sine wave (see FIG. 12) can be arbitrarily set by the phase amount setting unit 703.

Further, in order to vary the amplitude level of the signal transferred from the sinusoidal time data generation unit 704, the time amount product calculation unit 705 performs a product calculation (multiplication calculation) with the constant A (see FIG. 12). Further, the constant A can be arbitrarily set by the time amount constant setting unit 706.

The value obtained by the time product multiplication unit 705 is C
Then, C = A × sin (φ + B) (where φ = 2π / recording paper carrying roller period × time), and such a data value C is used as the timing correction amount.

Next, the time of image recording will be described.
When recording an image of a color, first, a command signal is transferred from the control unit 110B to the drive circuit 104, and the drive circuit 104 controls the drive motor 102 to rotate and drive the drive motor 102 at a constant speed. As a result, the drive motor 102 is rotationally driven to rotate the recording paper carrying roller 11. Then, the recording paper is started to be conveyed by the rotation of the recording paper conveying roller 11. A rotation detector 201 is provided on the recording paper conveyance roller 11 to detect its rotation, and the disk of the rotation detector 201 rotates in accordance with the rotation of the recording paper conveyance roller 11. One position marker hole is formed on the disk, and the photo coupler is provided so as to face the movement trajectory of the position marker hole. Therefore, when the position marker hole passes through the photo coupler position, A pulse signal will be generated from the photocoupler of the rotation detector 201. This pulse signal is transferred to the timing correction unit 202 and the control unit 110B.

Upon receipt of this pulse signal, the controller 110B
Outputs a reference recording timing signal t _s to the timing correction unit 701 so that the recording head 5 starts the recording operation. Then, the timing correction unit 701 outputs a start signal to the data generation control unit 702 in order to generate a signal from the sinusoidal time data generation unit 704.

As described above, the data generation control unit 702 controls the timing correction amount signal as shown in FIG. 12 so that the sinusoidal time data generation unit 704 can generate the timing correction amount signal in accordance with the rotation angle of the recording paper conveying roller 11. . The timing correction amount signal value C generated by the sinusoidal time data generation unit 704 is given to the timing correction unit 701.

When the timing correction unit 701 reads the timing correction amount signal value C, the timing correction unit 701 adds the timing value t _s to the timing correction amount signal value C, and the head control unit 108 outputs the signal at the timing thus obtained. Send to. Image data is also given to the head control unit 108 from the control unit 110B. Therefore, in the head control unit 108, the recording timing of the dots has the same relationship as in FIG.
Will be done by.

When the recording of the image of the first color is completed, the winding drive motor (not shown) controls the controller 7 so as to rewind the recording paper.
The drive is controlled by 07. The winding length is a preset length and the preset length is a little longer than the conveyed length after the start of recording.

The recording of the second color is a pulse generated from the photocoupler when the position marker hole in the disk of the rotation detector 201 passes through the photocoupler position in accordance with the rotation of the recording paper conveying roller 11 as described above. The signal is used as a trigger.

That is, the pulse signal is sent to the timing correction section 202 and the control section 110B, and with this as a reference,
The timing correction unit 202 and the control unit 110B control to start image recording in the same sequence as that for the first color. This operation is similarly performed from the second color onward until the image recording of the fourth color.

Before actually using such a mechanism for timing correction, it is necessary to match the constant A and the constant B to each color image recording apparatus.

Therefore, the setting adjustment of the time amount constant A and the phase amount B for giving this timing correction is required in advance. The setting adjustment of the time amount constant A and the phase amount B is performed by, for example, the first
After performing the printing process of the second color and the second color, and visually confirming the image recording output of the obtained two colors, or by measuring with another measuring device, the value is determined, and the determined value is determined. Set. This work may be calculated and set by another computer device as an adjustment work. In this way, the dot position is corrected with a simpler device configuration than the second embodiment.

Here, as in the second embodiment, the recording is always started from the same rotation angle position of the recording paper conveying roller. However, as in the first embodiment, the printing recording of the first color is performed. It is also possible to store the angular position of the recording paper transport roller at the start and control the configuration by changing the configuration so that the printing is started from that angular position when printing the second and subsequent colors. Further, similarly to the second embodiment, it is possible to start printing regardless of the rotation angle position of the recording paper conveyance roller.

In the above, the dot row print timing is shifted by an amount corresponding to the periodical change in the dot spacing irregularity in the sub-scanning direction due to the periodical change in the recording paper conveyance speed due to the roller eccentricity. As a result, the dot pitch is made uniform and the image quality is improved. However, even if the dot pitches are not made uniform, a method may be considered in which the density change that changes depending on the dot pitch irregularity is controlled by controlling the dot size in accordance with the irregularity state so that density irregularity does not occur. Therefore, an embodiment for realizing this method will be described as a fourth embodiment.

(Fourth Embodiment) Next, a fourth embodiment will be described. In this embodiment, the unevenness of the dot pitch is adjusted, and the density of the dots is adjusted according to the degree of the unevenness, thereby suppressing the density change caused by the unevenness of the dot pitch due to the periodical conveyance speed unevenness of the recording paper. It is an example of such a device. The dot density adjustment is performed by adjusting the dot size, for example.

FIG. 13 shows a block diagram of the fourth embodiment of the present invention. 11, the same members as those in FIG. 11 described above are denoted by the same reference numerals as those in FIG. 11, and detailed description thereof will be omitted.

In the embodiment shown in FIG. 13, the image data density correction unit 900, the data generation control unit 901, the phase amount setting unit 902, and the sinusoidal density correction are performed in order to correct the density change for each line due to the dot position shift. Data generator 90
3 is provided.

The image data density correction unit 900 adjusts the density of the image data from the control unit 110C in accordance with the unevenness of the conveyance speed of the recording paper and gives it to the head control unit 108. Further, the data generation control unit 901 sets the correction amount for correcting the density change for each line due to the dot position shift from the sinusoidal density correction data generation unit 903 to the density correction amount corresponding to the rotation angle position of the recording paper conveyance roller 11. The phase amount setting unit 90 controls to obtain the data.
Reference numeral 2 is for setting the phase amount F for matching the phase of the sinusoidal density correction characteristic corresponding to the phase of the recording paper conveyance speed characteristic due to the eccentricity of the recording paper conveyance roller 11. This phase amount F can be arbitrarily set variable.

The sinusoidal density correction data generation unit 903 generates density correction data for each line position for forming dots on the recording paper in response to periodic fluctuations in the recording paper transportation speed due to eccentricity of the recording paper transportation roller 11. The recording paper conveyance speed fluctuation is a periodic fluctuation, and in order to make the density look constant, the dot size is corrected corresponding to the recording paper conveyance speed fluctuation, so that the speed is fast. Since the density correction data is generated such that the size is increased and the size is decreased at a slow position, the transition of the data value has a sine wave shape.

The sinusoidal density correction data generation unit 903
For example, the density correction data is stored with the address position stored in association with the rotation angle position of the recording paper conveyance roller 11.
It is configured by an OM (Read Only Memory) or the like. Therefore, the density correction data can be read by designating the address in correspondence with the rotation angle position of the recording paper conveyance roller 11, and the read density correction data is given to the image data density correction unit 900. .

In the case of the sinusoidal density correction data generation unit 903 configured to hold the density correction data as a conversion table by the ROM as described above, the data generation control unit 9
01 may be configured as an address generator. And
The address to be generated is updated based on the pulse generated by the rotation detector 201 so as to correspond to the rotation angle position of the recording paper conveyance roller 11 rotated at a constant speed, and is given to the sinusoidal density correction data generation unit 903 to be read out. Should be specified. A phase setting unit 902 is provided to match the phase of the sine wave of the density correction data having the sinusoidal characteristic with the phase of the recording paper conveyance roller 11, and by matching the set values, the recording paper conveyance roller 11 It is possible to generate the necessary density correction data by matching the phase of the.

The image data density correction unit 900 has a function of applying density correction to the image data from the control unit 110C based on the density correction data and giving it to the head control unit 108 as density-corrected image data.

The image data density correction unit 900 can be realized by the structure as shown in FIG. 14A or the structure as shown in FIG.
Also, both configurations may be combined. FIG.
The image data density correction unit 900 shown in FIG. 4A includes a density ratio correction calculation unit 904, a density ratio setting unit 905, and a density product calculation unit 908. Of these, the density ratio setting unit 90
5 is for giving a desired set value D, and
The density ratio correction calculation unit 904 multiplies the output of the sinusoidal density correction data generation unit 903 and the output of the density ratio setting unit 905, and performs the density ratio correction calculation for varying the correction density ratio. Figure 15 shows the sinusoidal characteristics.
As shown in (a), it is converted into a characteristic in which a value "1" as a bias and a sine wave of amplitude D are added.

The density value correction data supplied from the sinusoidal density correction data generation unit 903 to the density ratio correction calculation unit 904 is the density correction for each line corresponding to the fluctuation of the recording paper conveyance speed due to the eccentricity of the recording paper conveyance roller. Since it is a size and needs to be set to a value that suits the actual condition for each device, the set value D from the density ratio setting unit 905 is used in order to give a constant for the adjustment. The configuration is such that the density value correction data from the correction data generation unit 903 is multiplied. As a result of such a configuration, the density ratio setting unit 90
By changing the set value D of 5, the amplitude of the sine wave in FIG.

The density product calculation unit 908 is the density ratio correction calculation unit 9
The correction data corrected by 04 and the image data are subjected to integration processing (multiplication processing), and the image data is subjected to density correction to obtain the optimum density corresponding to the transport speed by this multiplication. . By supplying the image data obtained by the density product calculation unit 908 to the head control unit 108, the head control unit 108 drives and controls the recording head 5 to print dots with the density value corresponding to the image data.

The image data density correction unit 900 shown in FIG. 14B is composed of a density addition amount ratio product calculation unit 906, an addition amount ratio setting unit 907, and a density addition calculation unit 909. Of these, the addition amount ratio setting unit 907 is for setting a desired set value E, and the concentration addition amount ratio product calculating unit 9
06 is for multiplying the output of the sinusoidal density correction data generation unit 903 and the output of the addition amount ratio setting unit 907. By this multiplication, the density addition amount required for the correction can be changed in accordance with the sinusoidal density correction characteristic, and the sinusoidal characteristic is converted into the sinusoidal characteristic of the amplitude E as shown in FIG. be able to.

The density addition calculation unit 909 is for adding the correction data corrected by the density addition amount ratio product calculation unit 906 and the image data, and by this addition, the optimum density corresponding to the transport speed is obtained. The image data is corrected. By supplying the image data obtained by the density product calculation unit 908 to the head control unit 108, the head control unit 108 drives and controls the recording head 5 to print dots with the density value corresponding to the image data.

The head controller 108 and the recording head 5 are the first
This is the same as the embodiment. The control unit 110C is for controlling the entire system.

Next, the operation will be described. The rotation angle of the recording paper conveyance roller is different for each recording line in order to prevent the density of the recording dots in the sub-scanning direction from approaching or separating due to the eccentricity of the recording paper conveyance roller 11. Dot density correction is performed according to. The change in density can be expressed by changing the size of the dots. For example, when the recording head 5 is an ion head, the applied voltage can be changed or the ion output time can be changed. Can be realized with.

First, the generation of the density correction data will be described. When the recording paper conveyance roller 11 is rotationally driven, the rotation detector 201 generates a pulse each time the recording paper conveyance roller 11 reaches a specific rotation angle position. Based on this pulse, the data generation control unit 901 knows the reference position of the rotation angle of the recording paper conveyance roller 11, and determines the recording paper conveyance roller 1
Addresses corresponding to changes in the rotation angle of 1 are sequentially generated. By giving the generated address to the sine wave density correction data generation unit 903, the sine wave data which is the basis of the correction value is read from the ROM and given to the image data density correction unit 900.

The image data density correction section 900 adds density correction to the image data from the control section 110C based on this density correction data, and supplies it to the head control section 108 as density-corrected image data.

The image data density correction unit 900 obtains the density correction data corresponding to the rotation angle of the recording paper conveyance roller obtained from the sinusoidal density correction data generation unit 903. The density ratio correction calculation unit 904 adjusts the density ratio, which is multiplied by the image data to adjust the density ratio of the image data according to the roller rotation angle. Then, this is given to the head control unit 108.

The head controller 108 controls the recording head 5 so that the image data is printed as dots in accordance with the dot recording timing signal t _s output by the controller 110C at regular time intervals.

On the other hand, the image data density correction unit 900 is shown in FIG.
In the case of the configuration of 4 (b), the density correction data corresponding to the rotation angle of the recording paper transport roller obtained from the sinusoidal density correction data generation unit 903 is multiplied by the density addition amount ratio product calculation unit 906 with the set value E. From the density addition calculation unit 909, the density data is added to the image data and is supplied to the head control unit 108. The head control unit 108 outputs this image data to the dot recording timing signal t _s which the control unit 110C outputs at a constant time interval.
The recording head 5 is controlled so as to print as dots in accordance with the above.

As described above, the density correction data output from the sinusoidal density correction data generation unit 903 corresponding to the rotation angle of the recording paper conveying roller is corrected by the image data density correction unit 900 to be used by the color image recording apparatus. Image data with density adjusted to characteristics, and using this for printing,
It is possible to suppress the density fluctuation caused by the dot density change due to the periodical change of the transport speed by the dot density adjustment. Next, the operation during actual image recording will be described.

At the time of image recording of the first color, first, the recording paper conveying roller 11 is rotationally driven at a constant speed by the drive motor 102, so that the recording paper is conveyed by the recording paper conveying roller 11. The drive motor 102 starts operating when a command signal is transferred from the control unit 110C to the drive circuit 104, and is rotated at a constant speed by the drive circuit control of the drive circuit 104. The disk of the rotation detector 201 is synchronously rotated by the rotation of the recording paper conveyance roller 11, and when the position marker hole reaches the photo coupler position, the rotation detector 201 is detected.
Outputs a pulse. Therefore, the recording paper conveying roller 1
A pulse is generated from the rotation detector 201 when the rotation angle reaches a predetermined angle by the rotation of 1.
Then, this pulse is transferred to the data generation control unit 901 and the control unit 110C. Receiving the signal, the recording head 5
The dot recording timing signal t _s is output from the controller 110C to the head controller 108 as a reference timing control signal so that the recording start operation can be performed.

As described above, the data generation control unit 901 corresponds to the rotation angle of the recording paper conveyance roller, as shown in FIG.
The density correction data as shown in FIG.
The sinusoidal density correction data generation unit 903 is controlled so as to generate it. An image data signal is given line by line from the control unit 110C to the image data density correction unit 900, and the image data density correction unit 900 uses the density correction data to add image data to a line corresponding to the rotation angle of the recording paper conveying roller (recording). A calculation for correcting the recording dot density at the paper nip point) is performed. Then, the corrected image data is transferred to the head control unit 108.

By the above operation, the dot density correction is performed for each line, and the recording process of the image data is performed by the recording head 5. When the image recording of the first color is completed, the winding driving motor (not shown) is driven and controlled by the control unit 110C so as to rewind the recording paper. The winding length is a preset length, and slightly exceeds the conveyed length after the start of recording.

The recording of the second color is performed in the same manner as described above, when the position marker hole of the rotation detector 201 passes through the photocoupler position in accordance with the rotation of the recording paper conveying roller, a pulse is output from the photocoupler of the rotation detector 201. Is generated,
By this pulse, image recording is started in the same sequence as the first color. This operation is similarly performed after the second color until the image recording of the fourth color.

Before actually using this density correction mechanism, the following adjustment is made (pre-adjustment). The setting adjustment of the density ratio constant D, the addition amount ratio constant E, and the phase amount F that give the density correction characteristics is optimally adjusted according to the characteristics of each color image recording apparatus to which the density correction mechanism is applied. I need to put it. This adjustment uses the image recording output of the first color or a plurality of colors from the color image recording apparatus to which the present density correction mechanism is applied.

Then, these image recording outputs are visually confirmed or measured by another measuring device to determine the value of the correction amount and manually input and set it. Alternatively, it is also assumed that statistically obtained data is used for the correction effect when the correction amount is visually observed from a large number of data.

As described above, since the apparatus is capable of performing the density correction with emphasis on the appearance, with respect to the timing correction of the second and third embodiments, even if the inter-dot distance varies. Regardless, color unevenness is corrected.

In the fourth embodiment as well, the second
Like the first and third embodiments, the recording is always started from the same rotation angle position of the recording paper conveying roller. However, as in the first embodiment, when the first color printing recording is started. It is also possible to store and control the angular position of the recording paper transport roller, and change and control the structure so that the printing is started from that angular position when printing the second and subsequent colors. Further, similarly to the second embodiment, it is possible to start printing regardless of the rotation angle position of the recording paper transport roller.

Further, in the third and fourth embodiments, the periodic fluctuation of the transport speed due to the eccentricity of the recording paper transport roller is regarded as the variation characteristic which changes in a sine wave shape, and is corrected. May be approximated to, or may be approximated to an elliptical shape, and if the change in the dot row due to uneven transport is not conspicuous, the intended purpose can be achieved. The function is not limited to the sine wave shape.

Although the details have been described based on the embodiments, the present invention includes the following inventions.

[1] A recording sheet conveying roller for reciprocating the recording sheet, and a recording means for recording images of different colors in the same area on the recording sheet when the recording sheet is moved forward by the recording sheet conveying roller. Detecting means for detecting the rotational angular position of the recording / conveying roller, storage means for storing the angular position of the recording paper conveying roller at the start of printing of the first color by the recording means, and second color by the recording means. Control means is provided to control the subsequent print recording so as to start from the angular position of the recording paper conveying roller at the start of print recording of the first color. The first embodiment corresponds to the embodiment of the present invention.

In this structure, since the image recording positions for the respective colors are the same, the contact position between the recording paper conveying roller with the eccentricity and the recording paper can be made to coincide with each other during the recording of each color. At the start of image recording, the rotation angle position of the recording paper transport roller is detected and stored, and the position is stored, and the rotation angle position of the recording paper transport roller at the start of image recording for the second and subsequent colors is set to the start of image recording for the first color. It works so as to be in the same position as the rotation angle position of the recording paper conveyance roller.

That is, in the case of this configuration, first, the rotation angle position of the recording paper conveyance roller is detected at the start of the image recording of the first color, the position is stored, and the recording paper conveyance at the start of the image recording of the second and subsequent colors is performed. As a result of functioning so that the rotation angle position of the roller is the same as the rotation angle position of the recording paper conveyance roller at the start of image recording of the first color, the rotation angle position of the recording paper conveyance roller at the start of image recording for each color Are the same, the periodic fluctuations of the recording paper conveyance speed due to the eccentricity of the recording paper conveyance rollers are the same, the dot positions of the image are not shifted for each color, and the image quality is improved.

Therefore, according to this structure, the influence of the change in the recording sheet moving speed due to the eccentricity of the recording sheet conveying roller on the recorded images can be made equal to each color image, and the color misregistration between the color images can be prevented. It can be prevented.

[2] Further, in the structure of the item [1], in the recording means, a nip point releasing means for releasing the nip point by the recording paper conveying roller of the recording sheet, and a nip releasing state by the nip point releasing means are provided. And a driving means for idling the recording paper carrying roller. The first embodiment corresponds to the embodiment of the present invention.

When such a structure is added to the structure of the above item [1], the rotation angle position of the recording / conveying roller is changed when the printing start position on the recording paper has just reached the recording position by the recording means. When it has not reached the reference position, the nip point releasing means releases the nip point of the recording sheet by the recording sheet conveying roller and idles the recording conveying roller. That is, based on the detection information of the rotational angle position of the recording / conveying roller by the detecting means, has it reached the angular position of the recording-paper conveying roller at the start of printing of the first color by the recording means stored in the storage means? The control unit checks whether or not it has reached the limit, and if it has not reached, the control unit temporarily stops the recording sheet conveyance and releases the recording sheet pressure contact with the recording conveyance roller. Then, in this state, the recording paper conveyance roller is idled, and when the rotational angle position of the recording paper conveyance roller reaches the reference position, the idling is stopped, and the recording paper is nipped by the recording paper conveyance roller again to Start transportation.

By this operation, the angular position of the recording paper transport roller at the time when the recording start position on the recording paper reaches the printing position by the recording means can be adjusted to the same position as the angular position of the first color. Become.

Therefore, in the case of this configuration, the rotation angle position of the recording paper conveying roller is detected at the time of starting the image recording of the first color, and the position is stored, and the recording paper conveying roller at the time of starting the image recording of the second color and thereafter. The rotation angle position of the recording paper conveyance roller at the start of image recording of the first color reliably functions as the same as the rotation angle position of the recording paper conveyance roller at the start of image recording of the first color. Since the positions are the same, the cyclic fluctuation state of the recording paper conveyance speed due to the eccentricity of the recording paper conveyance roller is accurately matched, the dot position of the image is not shifted for each color, and the image quality is further improved.

[3] Further, when the recording paper feed roller for reciprocating the recording paper and the forward movement of the recording paper by the recording paper feed roller, printing recording of line units in different colors in the same area on the recording paper is performed. Recording means for performing the above, a detecting means for detecting the rotational angle position of the recording and conveying roller, a registration mark recording means for recording a registration mark on a recording paper at a constant time interval, a reading means for reading the registration mark, and the resist. Calculation means for calculating the moving speed displacement of the recording paper at each rotational angular position of the recording paper conveying roller from the read information of the mark, and each rotational angular position of the recording paper conveying roller based on the calculated moving speed displacement of the recording paper. Data creating means for creating correction data for line-by-line print recording timing by the recording means, and the data creating means And a control means for controlling printing recording by the recording means based on the corrected data. The second embodiment corresponds to the embodiment of the present invention.

In the case of this construction, first, a registration mark is formed on the recording paper at the same timing as when the image is recorded, the registration mark is read, and the moving speed displacement of the recording paper at each rotation angle position of the recording paper conveying roller is obtained. Based on, the print timing correction data of the print dot is created. Image recording is performed by correcting the recording timing from the time of recording the image of the first color based on the correction data.

Therefore, since the positions of the recording dots in the respective colors are the same, the color misregistration is less noticeable, and the print images in line units within the same color image are arranged at uniform intervals in the sub-scanning direction. There is little change in density in the intermediate colors, and it is possible to make color unevenness invisible.

[4] Further, the recording paper conveying roller for reciprocating the recording paper, and when the recording paper is moved forward by the recording paper conveying roller, print recording in line units in different colors in the same area on the recording paper. Recording means for performing the above, function generating means for generating a periodic function in which one rotation of the recording / conveying roller is one cycle, and recording control for changing the line-by-line print recording timing by the recording means according to the periodic function. And a parameter setting unit for changing the parameter of the periodic function based on the image output by changing the print recording timing of each line by the recording control unit. The third embodiment corresponds to the embodiment relating to the present invention.

In the case of the construction of the item [4], in order to eliminate the deviation of the recording dot position of the image recording by the recording paper conveying roller having an eccentricity, the printing recording timing of each line is adjusted according to the eccentricity of the recording paper conveying roller. To correct.

Here, since the paper conveyance speed due to the eccentricity of the recording paper conveyance roller changes in a periodic function shape with one rotation of the recording paper conveyance roller as a cycle, the recording dot position deviation also becomes a periodic function shape. Therefore, the correction data is also the periodic function timing correction data. In addition, there is a parameter setting means that makes it possible to change the magnitude of the correction amount and to match the phase of the paper transport speed characteristic due to the eccentricity of the recording paper transport roller with the phase of the generated periodic function. Based on the correction data from the setting means, it works so that the image recording timing can be corrected line by line from the time of recording the image of the first color.

For this reason, since the recording dot positions of the respective colors coincide with each other, the color misregistration is less noticeable, and the print images of the line unit within the same color image are arranged at uniform intervals in the sub-scanning direction so that the intermediate color There is little change in density, and it is possible to make color unevenness invisible. Further, by providing the parameter setting means, the apparatus is simplified and the productivity is improved.

[5] Further, when the recording paper feed roller for reciprocating the recording paper and the forward movement of the recording paper by the recording paper feed roller, printing recording in line units in different colors in the same area on the recording paper. Recording means for performing the above, function generating means for generating a periodic function in which one rotation of the recording / conveying roller is one cycle, and recording control means for changing the print density of each line by the recording means according to the periodic function. When,
The recording control means comprises a parameter setting means for changing the parameters of the periodic function based on the image output by changing the print density in line units. The third embodiment corresponds to the embodiment relating to the present invention.

In this structure, in order to make it difficult to see the color unevenness due to the recording dot position deviation of the image recording by the recording paper conveying roller having an eccentricity, a common density change is given for each printing line during each color recording. In the density correction data creation, since the paper transport speed due to the eccentricity of the recording paper transport roller changes like a periodic function, the deviation of the recording dot position also becomes like a periodic function. The correction data is also generated so as to be the periodic functional density correction data, and the size of the correction amount can be changed by setting the parameter, and the phase of the paper conveyance speed characteristic due to the eccentricity of the recording paper conveyance roller and the generated cycle The position of the function can be adjusted. Then, based on the correction data thus obtained, the recording density is corrected from the time of recording the image of the first color so that the image can be recorded.

That is, in the configuration of the item [5], in order to eliminate the deviation of the recording dot position of the image recording by the recording paper conveying roller having an eccentricity, the printing recording in line unit is performed according to the eccentricity of the recording paper conveying roller. Correct the density.

Here, since the paper carrying speed due to the eccentricity of the recording paper carrying roller changes in a periodic function form having one cycle of the recording paper carry roller as a cycle, the recording dot position deviation also becomes a periodic function form. Therefore, the correction data is also the periodic function timing correction data. Further, it is possible to change the correction amount to some extent by setting parameters, and it is possible to match the phase of the paper transport speed characteristic due to the eccentricity of the recording paper transport roller with the phase of the generated periodic function. Then, based on the correction data, it can be made to function so that the image recording timing of each line can be corrected from the time of recording the image of the first color so that the image recording can be performed. Is less noticeable, and the print images of line units in the same color image are arranged at equal intervals in the sub-scanning direction, the density change in the intermediate color is small, and it is possible to make the color unevenness invisible. . Further, the provision of the parameter setting means simplifies the apparatus and improves productivity.

In particular, since the image density can be recorded by correcting the recording density from the time of recording the image of the first color, not only does the color shift become less noticeable due to the matching of the recording dot positions of each color, but also line by line. Density correction is performed by adjusting the density to be low in the areas where the lines are dense and high in the areas where the lines are rough, so that there is little density change between lines within the same color image, and color unevenness is even more noticeable. It becomes possible to lose it.

Although various embodiments have been described above, the present invention is not limited to the above-mentioned embodiments, and various modifications can be carried out.

[0199]

As described above, according to the present invention, it is possible to eliminate the color shift due to the eccentricity of the recording paper conveying roller and the color unevenness due to the density of the image dots to form a high quality color image. can get.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention,
FIG. 1 is a diagram showing an overall configuration of a color image recording apparatus in one embodiment of the present invention.

FIG. 2 is a diagram for explaining an embodiment of the present invention,
The block diagram which shows the detail of the principal part of the control system in 1st Example of this invention.

FIG. 3 is a diagram for explaining an embodiment of the present invention,
FIG. 6 is a diagram showing a print example of registration marks used in the present invention.

FIG. 4 is a diagram for explaining an embodiment of the present invention,
FIG. 6 is a diagram for explaining the operation of the present invention with respect to the correction of dot position deviation due to uneven transport speed.

FIG. 5 is a diagram for explaining an embodiment of the present invention,
FIG. 3 is a diagram for explaining a dot print state in the first embodiment of the present invention.

FIG. 6 is a diagram for explaining an embodiment of the present invention,
The block diagram which shows the detail of the principal part of the control system in 2nd Example of this invention.

FIG. 7 is a diagram for explaining an embodiment of the present invention,
The block diagram which shows the example which made the measuring system in 2nd Example of this invention into another apparatus structure.

FIG. 8 is a diagram for explaining an embodiment of the present invention,
The characteristic view for demonstrating the effect | action of the principal part in the 2nd Example of this invention.

FIG. 9 is a diagram for explaining an embodiment of the present invention,
8 is a timing chart showing dot recording timing in the second embodiment of the present invention.

FIG. 10 is a diagram for explaining the embodiment of the present invention and is a diagram for explaining the dot printing state in the second embodiment of the present invention.

FIG. 11 is a diagram for explaining the embodiment of the present invention and is a block diagram showing details of a main part of a control system in the third embodiment of the present invention.

FIG. 12 is a view for explaining the embodiment of the present invention and is a drawing for explaining the operation of the main part of the third embodiment of the present invention.

FIG. 13 is a diagram for explaining the embodiment of the present invention and is a block diagram showing details of a main part of a control system in the fourth embodiment of the present invention.

FIG. 14 is a diagram for explaining the embodiment of the present invention and is a block diagram showing a configuration example of an image data density correction unit in the fourth embodiment of the present invention.

FIG. 15 is a view for explaining the embodiment of the present invention and is a drawing for explaining the operation of the main part in the fourth embodiment of the present invention.

FIG. 16 is a diagram for explaining a conventional example.

FIG. 17 is a diagram for explaining a conventional example.

FIG. 18 is a diagram for explaining a conventional example.

[Explanation of symbols]

 5 ... Recording head 11 ... Recording paper conveying roller 102 ... Drive motor 104 ... Drive circuit 105 ... Counter section 106 ... Buffer 108 ... Head control section 110, 110A, 110B, 110C ... Control section 201 ... Rotation detector 202, 701 ... Timing Correction unit 203 ... Address control unit 204 ... Correction data unit 206 ... Marker position detector 207 ... Sensor drive unit 208 ... Calculation unit 209 ... Position shift amount calculation unit 210 ... Correction data table creation unit 702 ... Data generation control unit 703 ... Phase Amount setting unit 704 ... Sinusoidal time data generation unit 705 ... Time amount product calculation unit 900 ... Image data density correction unit 901 ... Data generation control unit 902 ... Phase amount setting unit 903 ... Sinusoidal density correction data generation unit 904 ... Density ratio Correction calculation unit 905 ... Density ratio setting unit 906 ... Density addition amount ratio product Part 907 ... addition amount ratio setting unit 908 ... density product unit

Claims (3)

[Claims] 1. A recording paper conveying roller for reciprocating a recording paper, and a recording means for recording images of different colors in the same area on the recording paper when the recording paper is moved forward by the recording paper conveying roller, Detecting means for detecting the rotational angular position of the recording and conveying roller; storage means for storing the angular position of the recording paper conveying roller at the start of printing of the first color by the recording means; and second and subsequent colors by the recording means. And a control means for controlling the printing recording to be started from the angular position of the recording paper conveying roller when the printing recording of the first color is started, and a color image recording apparatus. 2. A recording paper conveying roller for reciprocating the recording paper, and a recording for performing line-by-line printing recording in different colors in the same area on the recording paper when the recording paper is moved forward by the recording paper conveying roller. Means, detection means for detecting the rotational angle position of the recording / conveying roller, registration mark recording means for recording registration marks on a recording paper at regular time intervals, reading means for reading the registration marks, and reading the registration marks Calculation means for calculating the moving speed displacement of the recording paper at each rotational angular position of the recording paper conveying roller from the information, and the recording at each rotational angular position of the recording paper carrying roller based on the calculated moving speed displacement of the recording paper. Data creating means for creating the correction data of the print recording timing in line units by the means, and the data creating means Color image recording apparatus characterized by and a control means for controlling the printing recording by said recording means on the basis of the primary data. 3. A recording sheet conveying roller for reciprocating the recording sheet, and recording for performing line-by-line printing recording in different colors in the same area on the recording sheet when the recording sheet is moved forward by the recording sheet conveying roller. Means, function generating means for generating a periodic function in which one rotation of the recording / conveying roller is one cycle, and recording control means for changing the line-by-line print recording timing by the recording means according to the periodic function, A color image recording apparatus comprising: parameter setting means for changing a parameter of the periodic function based on an image output by changing the print recording timing of each line by the recording control means.