JPH0514632A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Object] The present invention provides an image adjusting apparatus that does not need to form an image on an image forming medium and that can accurately and accurately adjust image variations in a minimum time. The purpose is to According to the present invention, there is provided an image forming apparatus 1 having a reading unit for reading information on a document and an image forming unit for forming an image corresponding to the information read by the reading unit on an image forming medium. A storage means for storing the image information read by the image storage means, and an error between the physical position and the ideal position of the image information stored in the storage means, and the image stored in the storage means based on the obtained error. An image information processing unit 50 which replaces information with image information corresponding to an ideal position and is used for image formation. With this configuration,
Image variations can be automatically adjusted in a minimum amount of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus,
More specifically, the present invention relates to an image forming apparatus that prevents displacement of an image formed on an image forming medium.

[0002] Image adjustment.

[0003]

2. Description of the Related Art Generally, in an image forming apparatus such as a copying machine, when an image formed on a sheet has a variation such as a positional deviation among the apparatuses, an image adjusting operation is performed.

Here, the image adjustment work means that an operator measures the error with respect to an image having no positional deviation, etc., by relying on a jig such as a scale and visual perception for an image having a positional deviation. However, it means that adjustment of the mechanical portion or electrical adjustment is performed so as to correct the error. Then, an image is formed on the sheet and it is confirmed whether or not the above error is corrected. If necessary, the above image adjustment work is repeated many times.

[0005]

As described above, in the prior art, when adjusting the image position deviation of the formed image of each device, the image is always formed on the paper and the formed image is operated. Since the operator visually judges and makes adjustments by the operator's hand, there are the following problems.

(1) Since an image must be formed on a paper sheet at least once, time for forming an image and consumables necessary for image formation are required.

(2) Due to the individual difference in the human sense of judgment, the adjustment reference becomes ambiguous, the adjustment is not performed correctly, and new variations occur in each device.

(3) As the accuracy of the image adjustment is pursued, the image forming operation and the adjustment work must be repeated, and therefore the adjustment time is inevitably increased.

Therefore, an object of the present invention is to provide an image adjusting apparatus which does not need to form an image on an image forming medium and which can accurately and automatically adjust the image variation in a minimum time. And

[0010]

An image forming apparatus of the present invention comprises a reading means for reading image information on a document and an image forming means for forming an image corresponding to the image information read by the reading means on an image forming medium. And an error between the physical position and the ideal position of the image information stored in the storage unit and the storage unit for storing the image information read by the reading unit. Based on the image information processing means, the image information stored in the storage means is replaced with the image information corresponding to the ideal position for image formation.

[0011]

The operation of the image forming apparatus will be described below.

The reading means of the image forming apparatus scans the original document, reads the image information attached to the original document, and sends it to the storage means. The image information processing means obtains an error between the physical position and the ideal position of the image information based on the image information once stored in the storage means, and stores the error in the storage means based on the obtained error. The image information stored is replaced with the image information corresponding to the ideal position. further,
The image information processing means sends the replaced image information to the image forming means. As a result, the image forming unit forms an image on the image forming medium without variations such as displacement.

[0013]

EXAMPLES Examples of the present invention will be described in detail below.

The image forming apparatus 1 shown in FIG. 1 comprises a box-shaped apparatus main body 1A, and an original G set on a transparent glass original plate 2 is scanned on the upper portion of the apparatus main body 1A. A reading unit 3 for reading the image information attached to the lever document G is provided, and an image forming unit 4 is provided at the bottom. Reference numeral 5 is a document cover provided on the document table 2 so as to be openable and closable.

The reading means 3 includes, for example, a first carriage 7 on which an illumination lamp 6 as a light source is arranged, a second carriage 8 for bending an optical path by a mirror, a zoom lens 9,
The optical path length is corrected when the magnification is changed, and the mirror portion 10 that guides the reflected light from the original G to the photoelectric converter 11 serving as an image sensor, the photoelectric converter 11 that receives the reflected light from the original G, and these parts are provided. It is composed of a drive system (not shown) for changing the position.

On the first carriage 7, an illumination lamp 6 for irradiating the original G with light, a reflector 12 as a reflecting mirror for collecting the light from the illumination lamp 6 on the original surface, and a reflected light from the original G are provided. Mirror 1 that guides to the carriage 8 side of 2
3 is installed.

On the second carriage 8, a mirror 8a for guiding the light guided by the mirror 13 to the zoom lens 9,
8b is installed.

The mirror unit 10 includes two mirrors 10.
a and 10b, and their mirrors 1 according to the change of the optical path length corresponding to the selected magnification (copy magnification).
The positions of 0a and 10b are changed, and the light from the zoom lens 9 is guided to the photoelectric converter 11 by bending the optical path with the two mirrors 10a and 10b.

The photoelectric converter 11 is mainly composed of, for example, a CCD line image sensor (CCD sensor) and the like, and photoelectrically converts reflected light from the original G to convert the image of the original G into cyan (C), Separately output as green (G), yellow (Y), (or red (R), green (G), and blue (B)) color signals. in this case,
One pixel of the document G corresponds to three continuous elements (C, G, Y) of the CCD sensor. The output of the photoelectric converter 11 is output to an A / D converter 53 described later.

The mirrors 10a and 10b and the zoom lens 9 are moved by separate stepping motors (not shown). The zoom lens 9
The spiral shaft (not shown) is rotated by the corresponding stepping motor, and the movement of this shaft causes it to move in the optical axis direction.

The image forming means 4 is provided with a platen drum 22 located at the center of the apparatus main body 1A, as shown in FIG. The platen drum 22 is formed of an elastic body such as rubber around the platen drum 22.
It has a function as a platen roller for 4.
The platen drum 22 winds the paper P by rotating itself in the clockwise direction to prevent the paper P from shifting during the overlay printing.

Around the platen drum 22, pressure rollers 25 are provided at predetermined intervals to prevent the sheet from floating above the platen drum 22. The circumference of the platen drum 22 is a sheet P which is an image forming medium.
The maximum paper size is a little longer than the length in the longitudinal direction.

A thermal head 24 is arranged in the lower left portion of the platen drum 22. The thermal head 24 is attached to a radiator 24a integrally formed on the rear end surface of the holder. The ink ribbon 26 is interposed between the platen drum 22 and the thermal head 24.

A paper feed roller 41 is provided at a lower portion of the apparatus main body 1A so that the paper P as an image forming medium stored in the paper feed cassette 20 can be taken out one by one. Here, the paper feed cassette 20 is detachable from the side surface of the apparatus body 1A. Paper feed roller 4
The paper P picked up in 1 is sent by the carrying roller 42 to the registration roller 21 arranged obliquely above and left of the carrying roller 42, and the leading end of the paper P is aligned. After that, the sheet P is transferred by the registration rollers 21 toward the platen drum 22 via the guides 43, and is wound around the platen drum 22 by the gripper 23 and the pressure roller 25 attached to the platen drum 22. Will be sent correctly. The paper P supplied from the manual paper feed unit 46 is also wound around the platen drum 22 in the same manner as described above.

On the other hand, the frame of the apparatus main body 1A is provided with a gripper releasing pawl 70 corresponding to a transfer portion for transferring the paper P to the platen drum 22. The gripper releasing pawl 70 is avoided by the gripper 23 when the platen drum 22 rotates clockwise, and the gripper releasing pawl 70 when the platen drum 22 rotates counterclockwise.
Engage with the gripper 23.

The paper P, the front end of which is fixed by the gripper 23, is rotated clockwise to cause the platen drum 2 to rotate.
After being wound around 2, and the front end has passed the printing area, the thermal head 24 is pressed against the platen drum 22 to perform printing.

In FIG. 1, 27 is a paper ejection guide, 28 is a paper ejection tray, and 29 is a remelting roller.

Next, the main part of the control system of the image forming apparatus 1 will be described with reference to FIG.

This control system controls the entire memory 51 as a storage means for storing image information in the form of digital information, and also controls the whole and fetches the image information stored in the memory 51 to physically store the image information. The error between the position and the ideal position is calculated, and the memory 51 is based on the calculated error.
The image information processing means 50 including the CPU 55 and the data output start address register 56 for replacing the image information stored in the image information with the image information corresponding to the ideal position, and the analog from the photoelectric converter 11. A / D that converts information into digital information and sends it to the memory 51
The converter 53 and the image forming means 4 for executing the image forming operation under the control of the CPU 50 are provided.

Next, the operation of the image forming apparatus 1 having the above structure will be described with reference to FIGS.

In FIG. 1, the image information attached to the original G on the original table 2 is scanned by the first carriage 7, and the reflected light from the original G is reflected by the mirror 13, the mirrors 8a and 8b, the zoom lens 9, and the mirror. Follow the route of 10a, 10b,
The photoelectric conversion element 11 converts the electric signal.

An optical image OG normally projected on the photoelectric conversion element 11 by the above path is shown in FIG.

By the way, no matter how much the precision of parts and the precision of assembly are improved, when the photoelectric conversion element 11 is attached to the main body 1A of the apparatus, the projected optical image OG and the photoelectric conversion element 11 are relatively moved in the main scanning direction. It is difficult to reduce the position error to zero.

Further, in FIG. 3, when the photoelectrically converted image data in the range from LM0th to RM0th of the photoelectric conversion element 11 is used for actual image formation, the error of the apparatus main body 1A having a relatively large error described above. In this case, the range between the projected optical image OG and the image data actually used for image formation will deviate. That is, when an image is formed on the sheet P as an image forming medium, a main scanning deviation occurs.

Therefore, in this embodiment, the main scanning deviation is detected and corrected by the operation described below.

In the original G shown in FIG. 3, thick straight lines L are drawn at positions at equal intervals from the center of the original G. The document G is placed in conformity with the position of the leading edge of the document on the document table 2.

By the way, the image information of the photoelectric converter 11 capable of continuously reading an image in the main scanning direction is referred to as A
After converting to digital data with the / D converter 53,
The image information stored in the memory 51 is read out as digital data by the CPU 55.

The CPU 55 checks the number of pixels from the pixel end with reference to the value of the read digital data. The image information can be converted into a position in the main scanning direction by the number of pixels and the resolution of the photoelectric converter 11.

That is, the line L attached to the original G shown in FIG. 5 is scanned at an optical scanning position that intersects the straight line L at a right angle, and is projected on the photoelectric converter 11 having no optical magnification error or mounting error. The state is shown in FIG. A straight line L from the center of the document G
Let x be the distance to the center of thickness.

The straight line L on the original G is projected as light and darkness of light and converted into an electric signal by the photoelectric conversion element 11.
Further, after being converted into digital image information by the A / D converter 53, it is stored in the memory 51. Memory 5
The digital image information stored in 1 is discriminated by the CPU 55 as a difference in digital data.

Next, the center position of the two projected straight lines L is obtained. As shown in FIG. 6, assuming that the point having a larger number of pixels from the pixel end is C and the point having a smaller number of pixels is B, here,
Points B and C are the center points of the thickness of the straight line L, and b and c are the number of pixels up to their respective positions.

The length between the two straight lines L is bc (the number of pixels)
The center position M0 between the straight lines L is (c−b)
It can be expressed as / 2 + b = (c + b) / 2.

FIG. 7 shows a state of being projected on the photoelectric converter 11 having an optical magnification error and an attachment error. The center point of the two projected straight lines L is obtained as in the case of FIG. In this case, the length between the two straight lines L is represented by ed (the number of pixels), and the center position M1 between the straight lines L is (e-
It can be expressed as d) / 2 + d = (e + d) / 2.

Further, the error magnification is (ed) / (c-
It can be represented by d).

Here, points D and E are the center points of the thickness of the straight line L, and d and e are the number of pixels up to the respective positions.

Next, the main scanning shift of the digital image information can be obtained by the formula: (center position when there is an attachment error)-(center position without error) = M1-M0 (number of pixels).

Further, M0 is an ideal position and is defined by a numerical value in design. That is, it is known as a constant and can be prepared as fixed data in the CPU 55 in advance. Even if there is a magnification error, the center of the document G in the main scanning direction is made to coincide with the center of the document table 2 by M
The magnification error can be ignored because it means the original center of each of 0 and M1.

By the way, the digital image information directly used for image formation is such that the effective pixel start position is represented by the number of pixels from the pixel end in the main scanning direction as shown in FIGS.
It is defined by 0.

This LM0 is fixed by storing it in the data output start address register 56 which generates an address at the time of image output, with respect to the memory 51 which stores the digital data from the CPU 55. And the LM0
Is a design logical value, and therefore, as shown in FIG. 10, by adding (M1−M0) to LM0, the image information formed with the center of the document in the main scanning direction as a reference is replaced, and image shift Can be corrected.

When replacing the image information to be formed with the effective pixel start position as a reference, a value obtained by multiplying (M1-M0) by the error magnification may be added to LM0. That is, L
It may be M0 + (M1−M0) × (ed) / (cd).

Then, by redefining the above equation as LM0 and controlling the sending of the digital image information from the memory 51 to the image forming means 4, the image starting position of the image information formed on the paper P in the main scanning direction is Even if the photoelectric converter 11 has a positional deviation in the main scanning direction and a magnification error in the main scanning direction, the same image is always obtained. Note that RM0 also indicates RM0, which indicates the end point of the effective range of one main scanning line.
Needless to say, the same operation as.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made within the scope of the invention.

[0053]

As described above, according to the present invention, it is possible to automatically correct a main scanning deviation of an image formed without an actual image forming operation, and it is possible to avoid a judgment variation caused by an operator during image adjustment. It is possible to provide an image forming apparatus which eliminates the accompanying adjustment work itself and can perform the adjustment work accurately in a minimum time.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an image forming apparatus that is an embodiment of the present invention.

FIG. 2 is a block diagram of a control system of the image forming apparatus that is an embodiment of the present invention.

FIG. 3 is an explanatory view showing an optical image projected on a photoelectric converter of the apparatus of the embodiment.

FIG. 4 is a partial plan view showing a document for detecting an image shift in the apparatus of the embodiment.

FIG. 5 is an explanatory diagram of a straight line as a dimensional reference attached to a document for detecting image deviation in the apparatus of the embodiment.

FIG. 6 is an explanatory view showing a detection state of image shift in the apparatus of the embodiment.

FIG. 7 is an explanatory diagram showing an operation of correcting an image shift in the apparatus of the embodiment.

FIG. 8 is an explanatory diagram of a memory in the device of the embodiment.

FIG. 9 is an explanatory diagram of a memory in the device of the embodiment.

FIG. 10 is an explanatory view showing a storage state when an image shift of a memory in the apparatus of the embodiment.

[Explanation of symbols]

 1 image forming apparatus 3 reading means 4 image forming means 50 image information processing means 51 memory 55 CPU

Claims (1)

Claims: 1. A reading unit for reading image information on a document,
In an image forming apparatus having an image forming unit that forms an image corresponding to the image information read by the reading unit on an image forming medium, a storage unit that stores the image information read by the reading unit, and a storage unit that stores the image information. An error between the physical position of the image information and the ideal position is obtained, and the image information stored in the storage means is replaced with the image information corresponding to the ideal position based on the obtained error to form an image. And an image information processing unit for use in the image forming apparatus.