JPH11272035A - Multiple image forming device - Google Patents

Abstract

(57) [Problem] To provide a multiplex image forming apparatus capable of accurately performing color misregistration correction. SOLUTION: A plurality of sensors 21 and 22 are disposed on a line intersecting the rotation direction of an intermediate transfer belt 7 and detect a shift between toner images of respective colors, and a single light source for irradiating the sensors 21 and 22 with light. 23 and the sensors 21 and 22 from the light source 23.
Displacement measurement for measuring the displacement amount of the sensors 21 and 22 from the read value of the light irradiated and measured respectively and the value of the light from the light source 23 corresponding to the positions of the sensors 21 and 22 previously input. And a sensor 24 for a registration pattern 25 formed on the intermediate transfer body belt 7.
The color misregistration amount is measured in consideration of the misregistration amount of the sensors 21 and 22 measured by the misregistration measurement unit 24 on the reading result by the sensor 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a multiplex image forming apparatus for forming a composite image by superimposing image information on a transfer material using electrophotographic technology or the like.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus employing an electrophotographic technique, an electrophotographic photosensitive member as an image carrier is charged by a charger, and the photosensitive member is irradiated with light according to image information. 2. Description of the Related Art A latent image is formed, and the latent image is developed by a developing device, and a visualized toner image is transferred to a sheet material or the like to form an image.

On the other hand, a plurality of image carriers on which such a series of image forming processes are developed in accordance with colorization of an image are provided, and each color image of a cyan image, a magenta image, a yellow image, and preferably a black image is provided. Is formed on each image carrier, and a tandem-type image forming apparatus that forms a full-color image by superimposing and transferring each color image on a sheet material at a transfer position of each image carrier has also been proposed.

Since such a tandem type multiple image forming apparatus has an image forming unit for each color,
This is advantageous for speeding up. A technical problem is how to properly perform registration (registration) of each image formed by different image forming units. This is because the shift of the image forming positions of the four colors transferred to the sheet material eventually appears as a color shift or a change in color tone.

[0005] By the way, the types of positional deviation of the transferred image include a positional deviation in the scanning line writing direction (top margin) with respect to the transfer material and a positional deviation in the scanning direction (the direction orthogonal to the scanning line writing direction). (Left margin), a position shift in a diagonal direction, and a difference in magnification error. In reality, a superposition of these four types of shifts appears.

The main cause of the image shift is the shift of the image writing timing of each image forming station in the case of the top margin, and the writing timing of each image in each image forming station in the case of the left margin, that is, one line. This is a shift of the scan start timing in the scan line. In addition, in the case of a tilt shift in an oblique direction, it is the mounting angle shift of the scanning optical system or the angular shift of the rotation axis of the photosensitive drum. This is due to the deviation of the scanning line length due to the error of the optical path length up to the above.

In order to eliminate the four types of shifts as described above, the shift amounts of the top margin and the left margin are adjusted by adjusting the scanning timing of each color. Then, with respect to the magnification error deviation and the inclination deviation, the deviation amount is corrected by appropriately adjusting a plurality of folding mirrors provided in the middle of the optical path of each image forming station. In addition, as an actuator for adjusting the return mirror, a linear step actuator or the like provided with a step motor as a driving source that moves linearly stepwise is used.

[0008] In order to perform the processing for eliminating the shift, it is necessary to know the shift amount. Therefore, a reference pattern (hereinafter, referred to as “registration pattern”) is drawn in advance, the registration pattern is read by a plurality of sensors, and the amount of deviation is measured from the result.

[0009]

As described above, according to the conventional technique of reading a registration pattern using a sensor for detection, if the sensor is not accurately mounted on a reference straight line, the position of the sensor itself is deviated. As a result, the registration pattern cannot be measured accurately.

[0010] However, it is difficult to accurately mount the sensor, and a slight displacement of the mounting position will inevitably occur. As a result, it becomes impossible to correct the color shift accurately.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multiplex image forming apparatus capable of accurately correcting color misregistration.

[0012]

In order to solve this problem, a multiple image forming apparatus according to the present invention comprises a plurality of photoconductors provided corresponding to respective color toner images to be developed, and a plurality of photoconductors. A plurality of charging means for uniformly charging the surface of the photoconductor, and an exposure means for irradiating the charged photoconductor with an exposure light beam corresponding to image data of a specific color to form an electrostatic latent image. A plurality of developing means provided for each photoconductor to visualize an electrostatic latent image formed on the photoconductor, and a single-color image of each color provided on each photoconductor and formed on the photoconductor. A plurality of transfer means for sequentially superimposing and transferring the image on the intermediate transfer body, a plurality of sensors arranged on a line intersecting the rotation direction of the intermediate transfer body and detecting a shift between the toner images of each color, and irradiating light to the sensors. A single light source and A displacement measurement means for measuring the displacement of the sensor from the read value of the light measured and illuminated on the sensor and the value of the light from the light source corresponding to the position of the sensor previously input, The configuration is such that the amount of color misregistration is measured in consideration of the amount of misregistration of the sensor measured by the misalignment measuring means based on the result of reading the registration pattern formed on the intermediate transfer member by the sensor.

Thus, since the amount of color misregistration is measured in consideration of the amount of misregistration of the sensor itself in the result of reading the registration pattern by the sensor, color misregistration can be accurately corrected.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides a plurality of photoconductors provided corresponding to each color toner image to be developed, and a photoconductor provided for each photoconductor. A plurality of charging means for uniformly charging the photosensitive member, an exposure means for irradiating an exposed light beam corresponding to image data of a specific color onto the charged photosensitive member to form an electrostatic latent image, and provided for each photosensitive member. And a plurality of developing means for visualizing the electrostatic latent image formed on the photoconductor, and a single color image of each color formed on the photoconductor is provided on each of the photoconductors sequentially on the intermediate transfer body. A plurality of transfer means for overlapping transfer,
A plurality of sensors arranged on a line intersecting the rotation direction of the intermediate transfer body and detecting a shift between the toner images of each color, a single light source for irradiating light to the sensor, and each sensor being irradiated from the light source to each sensor A displacement measuring means for measuring a displacement of the sensor from a measured light reading value and a value of light from a light source corresponding to a previously inputted sensor position, and formed on the intermediate transfer member. This is a multiplex image forming apparatus that measures the amount of color misregistration by taking into account the amount of misregistration of the sensor measured by the misregistration measuring means based on the result of reading the registered pattern by the sensor. Since the amount of color misregistration is measured in consideration of the amount of misregistration, there is an effect that color misregistration can be accurately corrected.

The invention according to claim 2 of the present invention provides:
A plurality of photoconductors provided corresponding to each color toner image to be developed, a plurality of charging means provided for each photoconductor and uniformly charging the surface of the photoconductor, Exposure means for forming an electrostatic latent image by irradiating an exposure light beam corresponding to image data of a specific color, and a plurality of exposure means provided for each photosensitive member and for visualizing the electrostatic latent image formed on the photosensitive member Developing means, and a plurality of transfer means provided for each photoreceptor, for sequentially superimposing and transferring a single-color image of each color formed on the photoreceptor onto the intermediate transfer body, intersecting the rotation direction of the intermediate transfer body. A plurality of sensors arranged on the line and detecting a shift between the toner images of each color, a plurality of light sources installed corresponding to the plurality of sensors, and irradiating each sensor with light, and a light source irradiating each sensor. Reading of each measured light Means for measuring the amount of displacement of the sensor from the measured value and the value of the light from the light source corresponding to the position of the sensor which has been input in advance, and a displacement measurement means for measuring the displacement of the sensor. This is a multiplex image forming apparatus that measures the amount of color misregistration in consideration of the amount of misregistration of the sensor measured by the misregistration measuring means in the result of reading by the sensor. Has an effect that even if the position of the measurement sensor cannot be displaced by a single light source due to a large displacement, an accurate displacement can be detected.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

(Embodiment 1) FIG. 1 is an explanatory view showing a configuration of a multiplex image forming apparatus according to Embodiment 1 of the present invention, and FIG.
FIG. 3 is an explanatory diagram showing an arrangement of sensors for performing color misregistration correction in the multiple image forming apparatus of FIG. 1.

As shown in FIG. 1, the multiplex image forming apparatus of the present embodiment has four image forming stations Pa and P.
b, Pc, and Pd are arranged. Each of the image forming stations Pa, Pb, Pc, and Pd has photoconductor drums (photoconductors) 1a, 1b, 1c, and 1d as image carriers.

Around the photosensitive drums 1a, 1b, 1c, 1d, charging means 2a, 2b, which uniformly charge the surface of each of the photosensitive drums 1a, 1b, 1c, 1d to a predetermined potential.
2c, 2d, charged photosensitive drums 1a, 1b, 1
Exposure light rays 3 corresponding to image data of a specific color on c and 1d
Exposure means 3 for irradiating K, 3C, 3M, 3Y to form an electrostatic latent image; developing means 4a for visualizing the electrostatic latent images formed on the photosensitive drums 1a, 1b, 1c, 1d; 4b, 4
c, 4d, transfer means 5a, 5b, 5c, 5d for transferring the toner image visualized on the photosensitive drums 1a, 1b, 1c, 1d to an endless intermediate transfer belt (intermediate transfer body) 7.
After transferring the toner image from the photoreceptor belts 1a, 1b, 1c, 1d to the intermediate transfer belt 7, the photoreceptor belts 1a, 1
Cleaning means 6a, 6b, 6c, 6d for removing the residual toner remaining in b, 1c, 1d are arranged, respectively.

Here, the exposing means 3 comprises the photosensitive drum 1
They are arranged with a predetermined inclination with respect to a, 1b, 1c and 1d. The intermediate transfer belt 7 rotates in the direction of arrow A in the illustrated case. In the image forming stations Pa, Pb, Pc, and Pd, a black image, a cyan image, a magenta image, and a yellow image are formed, respectively. The photosensitive drums 1a, 1b, 1c,
The single-color images of each color formed in 1d are sequentially superimposed and transferred onto the intermediate transfer belt 7 to form a full-color image.

On a line perpendicular to the rotation direction of the intermediate transfer belt 7, a sensor 14 for examining a shift between toner images formed by each color is arranged. The sensor 14 will be described later.

At the lower part of the apparatus, there is provided a paper feed cassette 10 in which sheet materials 9 such as printing paper are stored. Then, the sheet material 9 is sent out from the sheet feeding cassette 10 to the sheet conveying path one by one by the sheet feeding roller 8.

The intermediate transfer belt 7 comes into contact with the outer peripheral surface of the intermediate transfer belt 7 for a predetermined amount on the paper transport path.
A sheet material transfer roller 11 for transferring the color image formed thereon to the sheet material 9, and a fixing device for fixing the color image transferred on the sheet material 9 to the sheet material 9 by the pressure and heat associated with the pinching rotation of the roller. A vessel 12 is arranged.

In the multiplex image forming apparatus having such a configuration, first, a latent image of the black component color of the image information is formed on the photosensitive drum 1a by the charging unit 2a and the exposing unit 3 of the image forming station Pa. This latent image is visualized as a black toner image by the developing unit 4a having black toner by the developing unit 4a, and is transferred as a black toner image onto the intermediate transfer belt 7 by the transfer unit 5a.

On the other hand, while the black toner image is being transferred to the intermediate transfer belt 7, a latent image of a cyan component color is formed in the image forming station Pb, and then the developing unit 4b
Thus, the cyan toner image by the cyan toner is visualized.
Then, the cyan toner image is transferred by the transfer means 5b of the image station Pb to the intermediate transfer belt 7 where the transfer of the black toner image has been completed in the previous image station Pa, and is superimposed on the black toner image.

Hereinafter, image formation is performed in the same manner for the magenta toner image and the yellow toner image, and when the superposition of the four color toner images on the intermediate transfer belt 7 is completed,
Sheet material transfer rollers 11 collectively transfer four color toner images onto sheet material 9 fed from sheet cassette 10 by sheet feed roller 8. Then, the transferred toner image is heated and fixed to the sheet material 9 by the fixing device 12, and a full-color image is formed on the sheet material 9.

Each of the photosensitive drums 1a, 1b, 1c and 1d after the transfer is completed is connected to a cleaning unit 6a,
At 6b, 6c and 6d, the residual toner is removed, and is prepared for the next image formation to be performed subsequently.

As described above, the sensor 14 is disposed in a direction orthogonal to the rotation direction of the intermediate transfer belt 7. The sensor 14 detects a shift between the toner images of each color before forming an image. That is, the sensor 14 reads a registration pattern such as a straight line or a graphic transferred to the intermediate transfer belt 7 to measure a shift amount, and corrects a color shift by a color shift correcting unit based on the shift amount. In this embodiment and the second embodiment described below, the sensor 14 is
Although three are provided, three or more may be provided.

As shown in FIG. 2, the displacement measuring means 24
Are arranged so as to form a straight line that intersects the rotation direction of the intermediate transfer belt 7. Then, the registration pattern 25 formed on the intermediate transfer belt 7 is read by the sensors 21 and 22, and the shift amount of each color is measured. The sensor 21
And the sensor 22 must be arranged so as to form a straight line orthogonal to the rotation direction of the intermediate transfer belt 7. However, here, since the sensor 22 is mounted shifted, Not.

Here, in order to use the straightness of light as a reference for measuring the displacement of the mounting position of the sensor itself,
A light source 23 is provided. Then, the sensors 21 and 22
Are arranged in the direction in which light from the light source 23 is projected. In addition, the read values of the light projected from the light source 23 when the sensors 21 and 22 are arranged at normal positions and when the sensors 21 and 22 are misaligned are measured in advance by the misalignment measuring unit 24 and held.

Therefore, before reading the registration pattern 25, the sensors 21 and 22 read the light emitted from the light source 23 and compare the read light with the value held in advance by the displacement measuring means 24, thereby detecting the sensor itself. Is detected, the amount of displacement from the place where the original should be arranged is detected. And the cash register pattern 25
By taking into account the amount of displacement of the sensor with respect to the result of reading, it is possible to accurately measure the position of the registration pattern, that is, the amount of color misregistration.

(Embodiment 2) FIG. 3 is an explanatory diagram showing an arrangement of sensors for performing color misregistration correction in a multiplex image forming apparatus according to Embodiment 2 of the present invention.

As shown in FIG. 3, the displacement measuring means 34
Are arranged so as to form a straight line that intersects the rotation direction of the intermediate transfer belt 7. Then, the registration pattern 35 formed on the intermediate transfer belt 7 is read by the sensors 31 and 32, and the shift amount of each color is measured. Also in the present embodiment, the sensor 31 and the sensor 32 must be arranged so as to form a straight line orthogonal to the rotation direction of the intermediate transfer belt 7.
This is not the case because the two are offset.

Here, a light source 33 and a light source 33b for irradiating light toward the sensors 31 and 32 are provided in correspondence with the sensors 31 and 32, respectively, in order to determine the displacement of the mounting position of the sensors. .

The sensor 31 and the sensor 32 read the reading values of the light projected from the light source 33 and the light source 33b when the sensors 31 and 32 are arranged at normal positions and when the sensors 31 and 32 are misaligned. Measured in advance by 34 and held.

Therefore, before reading the registration pattern, the sensors 31 and 32 read the light projected from the light source 33 and the light source 33b and compare them with the values held in advance by the displacement measuring means 34.
A positional shift amount is detected as how much the sensor itself is shifted from a place where the sensor should be arranged. Then, by reflecting the shift amount of the sensor itself in the reading result of the registration pattern 35, the color shift amount can be accurately measured.

The direction in which light is projected from the plurality of light sources 33, 33b may be any position as long as it can be considered as a mounting position of the sensors 31, 32.
And the projection direction between the light source 33 and the light source 33b are not limited. Further, the light sources 33, 33
When the light is projected from the light source b and the light is read by the sensors 31 and 32, the processing for the number of the light sources 33 and 33b may be performed at a later time, or the light from the plurality of light sources 33 and 33b may be simultaneously emitted. And the light may be read by the sensors 31 and 32.

As shown in FIG. 3, by preparing a plurality of light sources 33 and 33b, the mounting positions of the sensors 31 and 32 are greatly shifted, and when the position of the measurement sensor cannot be shifted by a single light source. Also, it is possible to detect an accurate displacement amount.

[0039]

As described above, according to the present invention, the amount of color misregistration is measured in consideration of the amount of misregistration of the sensor itself in the reading result of the registration pattern by the sensor. There is an effective effect that it is possible to perform accurately.

As a result, since there is no shift of each pixel when the toner images of the respective colors are superimposed, it is possible to obtain an effective effect that a high-quality image without image deterioration can be obtained.

If a plurality of light sources corresponding to the sensors are prepared,
Even if the position of the sensor is significantly displaced and the measurement sensor cannot be displaced by a single light source,
An effective effect that an accurate position shift amount can be detected is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a multiplex image forming apparatus according to a first embodiment of the present invention;

FIG. 2 is an explanatory diagram showing an arrangement of sensors for performing color misregistration correction in the multiplex image forming apparatus of FIG. 1;

FIG. 3 is an explanatory diagram showing an arrangement of sensors for performing color misregistration correction in a multiple image forming apparatus according to Embodiment 2 of the present invention;

[Explanation of symbols]

 1a, 1b, 1c, 1d Photoconductor drum (photoconductor) 2a, 2b, 2c, 2d Charging means 3 Exposure means 4a, 4b, 4c, 4d Developing means 5a, 5b, 5c, 5d Transfer means 7 Intermediate transfer belt (intermediate) (Transfer body) 14 sensor 21 sensor 22 sensor 23 light source 24 displacement measuring means 25 registration pattern 31 sensor 32 sensor 33 light source 33b light source 35 registration pattern

Claims (2)

[Claims] A plurality of photoconductors provided corresponding to each color toner image to be developed; a plurality of charging means provided for each of the photoconductors, for uniformly charging the surface of the photoconductor; Exposure means for forming an electrostatic latent image by irradiating an exposed light beam corresponding to image data of a specific color onto the charged photoconductor, provided for each photoconductor, formed on the photoconductor A plurality of developing means for visualizing the electrostatic latent image; and a plurality of transfer means provided for each of the photoconductors, for sequentially transferring a single-color image of each color formed on the photoconductor onto an intermediate transfer body. Means, disposed on a line intersecting the rotation direction of the intermediate transfer body,
A plurality of sensors for detecting a shift between the toner images of the respective colors; a single light source for irradiating the sensor with light; and a read value of light measured and illuminated from the light source to each of the sensors. And a displacement measuring means for measuring a displacement of the sensor from a value of light from the light source corresponding to a position of the sensor. The registration pattern formed on the intermediate transfer body is measured by the sensor. A multiplex image forming apparatus, wherein a color shift amount is measured in consideration of a position shift amount of the sensor measured by the position shift measuring unit in a reading result. 2. A plurality of photoconductors provided corresponding to each color toner image to be developed, a plurality of charging units provided for each of the photoconductors, and configured to uniformly charge the surface of the photoconductor, Exposure means for forming an electrostatic latent image by irradiating an exposed light beam corresponding to image data of a specific color onto the charged photoconductor, provided for each photoconductor, formed on the photoconductor A plurality of developing means for visualizing the electrostatic latent image; and a plurality of transfer means provided for each of the photoconductors, for sequentially transferring a single-color image of each color formed on the photoconductor onto an intermediate transfer body. Means, disposed on a line intersecting the rotation direction of the intermediate transfer body,
A plurality of sensors for detecting a shift between the toner images of the respective colors; a plurality of light sources installed in correspondence with the plurality of sensors; and a plurality of light sources for irradiating each of the sensors with light; A position deviation measuring unit for measuring a position deviation amount of the sensor from a measured light reading value and a value of light from the light source corresponding to the position of the sensor which has been input in advance, the intermediate transfer A multiplex image forming apparatus, wherein a color shift amount is measured in consideration of a position shift amount of the sensor measured by the position shift measuring unit in a reading result of the registration pattern formed on the body by the sensor.