JP2000098686A - Multiple picture forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of picture quality caused by tilt-deviation of a scanning line. SOLUTION: This device has an electrifying means electrifying uniformly surfaces of photosensitive drums 1a-1d, an exposure means 3 in which latent image lines formed on the photosensitive drum 1a-1d by irradiating scanning lines corresponding to picture data of specific colors are arranged so as to have the prescribed tilt for rotary shafts of the photosensitive drums 1a-1d and electrostatic latent images are formed on the photosensitive drums 1a-1d, a developing means 4a-4d developing the electrostatic latent image, and a transcription means superimposing successively and transcribing monochrome pictures formed on the photosensitive drums 1a-1d on an intermediate transcription belt. And rotary speed of the photosensitive drums 1a-1d is controlled so that tilts of transcription lines to which a latent image line (e) extending to a scan finish point E from a scan start point D set at an opposed side to a contact point R with an intermediate transcription belt in the photosensitive drums 1a-1d in the direction of width of the photosensitive drums 1a-1d is developed are made equal.

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 full-color image is formed by superimposing and transferring each color image on a sheet material at a transfer position of each image carrier.

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.

[0005] This is because the shift of the image forming positions of the four colors transferred to the sheet material finally appears as a color shift or a change in color tone.

[0006] Here, the type of the displacement of the transferred image is shown in FIG.
Shown in As shown in the figure, the types of positional deviation of the transferred image include a positional deviation (top margin) in the scanning line writing direction (the direction of arrow A in the figure) with respect to the transfer material 9 (FIG. 5).
(A)), misalignment (left margin) in the scanning direction (arrow B direction perpendicular to the arrow A direction in the drawing, which is the scanning line writing direction) (left margin) (FIG. 5B), and misalignment in the oblique direction (FIG. 5 (c)) and a deviation of the magnification error (FIG. 5 (d)). In reality, a superposition of these four types of deviations appears.

The main cause of the image shift is shown in FIG.
In the case of the top margin shown in FIG. 5, the image writing timing of each image forming station is shifted. In the case of the left margin shown in FIG. 5B, the writing timing of each image in each image forming station, that is, in one scanning line. This is a shift in the scan start timing. FIG.
In the case of the tilt shift in the oblique direction shown in FIG. 5C, it is the mounting angle shift of the scanning optical system or the angle shift of the rotation axis of the photosensitive drum. In the case of the shift due to the magnification error shown in FIG. This is due to the deviation of the scanning line length due to the error of the optical path length from the scanning optical system of the forming station to the photosensitive drum.

In order to eliminate the above four kinds of shifts, the shift amounts of the top margin and the left margin are adjusted by adjusting the scanning timing of each color. In order to deal with a magnification error deviation and a tilt deviation, in the correction device of the conventional multiplex image forming apparatus shown in FIG. 6, three folding mirrors 101, 102, and 105 installed in the optical path of each image forming station are used. Among them, a pair of folding mirrors 101 and 102 whose mirror surfaces are held at right angles to each other and are arranged in a substantially C shape are connected to actuators 103 and 104.
The shift amount is corrected by independently adjusting in the arrow M direction and the arrow N direction with respect to the apparatus main body. Note that the actuators 103 and 10 for performing such adjustment are provided.
As 4, a linear step actuator or the like provided with a step motor, which is a drive source that moves linearly stepwise, is used.

[0009]

However, in the above-mentioned conventional multiple image forming apparatus, vibrations are likely to occur because the structure for the inclination shift correcting means is particularly complicated and there are many components. For this reason, the position of the scanning line irradiated on the photoconductor is blurred, causing scanning unevenness, and the scanning unevenness appears as the density of the output image, thereby significantly deteriorating the image quality.

[0010] Such a problem is very serious in forming a high-quality image without color shift in a digital color multiplex image forming apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multiplex image forming apparatus capable of preventing image quality deterioration due to scanning unevenness due to deviation of scanning line inclination.

[0012]

In order to solve this problem, a multiplex 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 photoconductor for each photoconductor. A plurality of charging means for uniformly charging the surface of the photoconductor, and a latent image line formed on the photoconductor by irradiating a scanning line corresponding to image data of a specific color with respect to a rotation axis of the photoconductor. Exposure means for forming an electrostatic latent image on the photoreceptor and provided for each photoreceptor to visualize the electrostatic latent image formed on the photoreceptor A plurality of developing means, a plurality of transfer means provided for each photoconductor, and a plurality of transfer means for sequentially superimposing and transferring a single-color image of each color formed on the photoconductor onto an intermediate transfer body; Scan open set on the side opposite to the contact with The peripheral speed of each photoconductor is controlled so that the latent image line extending from the point to the scanning end point in the width direction of the photoconductor is developed and the inclination of the transfer line transferred to the intermediate transfer member becomes equal. It was done.

[0013] This eliminates the deviation of each pixel when the optical scanning images by the exposure means are superimposed, so that a high-quality image without image deterioration due to scanning unevenness due to the inclination deviation of the scanning line can be obtained.

Further, the multiplex image forming apparatus according to the present invention comprises:
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, and corresponding to image data of a specific color. Exposure means for arranging a latent image line formed on the photoconductor by irradiating the scanning line with a predetermined inclination with respect to the rotation axis of the photoconductor, and forming an electrostatic latent image on the photoconductor, A plurality of developing means provided for each photoconductor, for visualizing an electrostatic latent image formed on the photoconductor,
A plurality of transfer means provided for each photoconductor, for sequentially superimposing and transferring a single-color image of each color formed on the photoconductor onto the intermediate transfer member, and a side of the photoconductor opposite to a contact point with the intermediate transfer member. The peripheral speed of each photoconductor is developed so that the inclination of the transfer line transferred to the intermediate transfer body by developing the latent image line extending from the scanning intermediate point set in Is controlled.

This eliminates the displacement of each pixel when the optical scanning images by the exposure unit are superimposed, so that a high-quality image free from image deterioration due to scanning unevenness due to the inclination deviation of the scanning line can be obtained.

[0016]

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 image data, and irradiating a scanning line corresponding to image data of a specific color so that a latent image line formed on the photoconductor has a predetermined inclination with respect to a rotation axis of the photoconductor. Exposure means for forming an electrostatic latent image on the photoreceptor, a plurality of developing means provided for each photoreceptor and visualizing the electrostatic latent image formed on the photoreceptor, And a plurality of transfer means for sequentially superimposing and transferring a single-color image of each color formed on the photoreceptor onto the intermediate transfer member, and provided on a side of the photoreceptor opposite to a contact point with the intermediate transfer member. Scan end point in the width direction of the photoconductor from the set scan start point Is a multiplex image forming apparatus that controls the peripheral speed of each photoconductor so that the inclination of the transfer line transferred to the intermediate transfer body by developing the latent image line extended by Since there is no shift of each pixel in the case of superimposing, there is an effect that it is possible to obtain a high-quality image without image degradation caused by scanning unevenness due to a scan line tilt shift. In addition, even if the inclination of the transfer image on the intermediate transfer member is adjusted in the main scanning direction and the sub-scanning direction after the alignment, the position of the scanning start point does not change. It has the effect that it becomes possible.

According to a second aspect of the present invention, there are provided a plurality of photoconductors provided corresponding to each color toner image to be developed, and a plurality of photoconductors provided for each of the photoconductors so that the surface of the photoconductor is uniformly formed. A plurality of charging means for charging, and arranged such that a latent image line formed on the photoconductor by irradiating a scanning line corresponding to image data of a specific color has a predetermined inclination with respect to the rotation axis of the photoconductor, Exposure means for forming an electrostatic latent image on the photoreceptor, a plurality of developing means provided for each photoreceptor to visualize the electrostatic latent image formed on the photoreceptor, and for each photoreceptor A plurality of transfer means for sequentially transferring a single-color image of each color formed on the photosensitive member onto the intermediate transfer member, and a scanning intermediate set on the photosensitive member on a side opposite to a contact point with the intermediate transfer member. Extends from the point to the scanning end point in the width direction of the photoconductor This is a multiplex image forming apparatus that controls the peripheral speed of each photoconductor so that the inclination of the transfer line transferred to the intermediate transfer body by developing the latent image line is the same. In this case, since there is no shift between the pixels, there is an effect that it is possible to obtain a high-quality image without image degradation due to scanning unevenness due to a scan line tilt shift. Further, since the deviation between the scanning end point and the rotation axis of the photoconductor is reduced, it is possible to reduce the print curvature and the depth of focus error in the photoconductor constituted by the curved surface.

FIG. 1 shows an embodiment of the present invention.
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.

FIG. 1 is an explanatory diagram showing a configuration of a multiplex image forming apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a relationship between an exposure unit and a photosensitive drum in the multiplex image forming apparatus of FIG. FIG. 3 is an explanatory view showing an example of the relationship between the photosensitive drum and the intermediate transfer belt in the multiplex image forming apparatus of FIG. 1, and FIG. 4 is the relationship between the photosensitive drum and the intermediate transfer belt in the multiplex image forming apparatus of FIG. It is explanatory drawing which shows another example of.

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 means 3 for irradiating scanning lines 3K, 3C, 3M, 3Y of laser beams corresponding to specific color image data on c and 1d to form an electrostatic latent image, and photosensitive drums 1a, 1b, 1
developing means 4a, 4b, 4c, 4d for visualizing an electrostatic latent image formed on the photosensitive drums 1a, 1b, 1d;
transfer means 5a, 5 for transferring the toner image visualized on c, 1d to an endless intermediate transfer belt (intermediate transfer body) 7
b, 5c, 5d, photosensitive drums 1a, 1b, 1c, 1d
Cleaning means 6a, 6b, 6c, 6d for removing the residual toner remaining on the photosensitive drums 1a, 1b, 1c, 1d after transferring the toner image to the intermediate transfer belt 7, respectively.

Here, the exposing means 3 includes 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.

At the lower part of the apparatus, there is provided a paper feed cassette 10 containing sheet materials 9 such as printing paper. 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, a latent image of a black component color of 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.
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, in an apparatus having a plurality of image forming stations Pa, Pb, Pc and Pd, the scanning lines 3K and 3K of the laser beam emitted from the exposure means 3 are used.
The image information is exposed on the photosensitive drums 1a, 1b, 1c, 1d rotating in the direction of arrow C in the figure by C, 3M, 3Y, and subsequently visualized by developing means 4a, 4b, 4c, 4d, respectively. Then, the images are sequentially transferred onto the same surface of the common intermediate transfer belt 7 which rotates in the direction of arrow A in the drawing.

Then, each image forming station Pa, P
When the transfer image position in b, Pc, and Pd deviates from the ideal position, for example, in the case of a multicolor image, the image intervals of different colors are shifted or overlapped. Further, in the case of a color image, a difference in color and, if the degree of color difference becomes more severe, a color shift appears, which significantly deteriorates the image quality.

Therefore, in the present embodiment, the following correction is performed in order to eliminate the positional deviation of the four types of transferred images which causes the color deviation described with reference to FIG.

That is, with respect to the top margin and the left margin, the scanning timing of the scanning lines 3K, 3C, 3M, and 3Y is electrically adjusted to correct the shift amount.

Further, the scanning line 3
The video clock rates of K, 3C, 3M, and 3Y are electrically modulated to correct the shift amount.

Then, with respect to the positional shift in the oblique direction, that is, the tilt shift (skew), the shift amount is corrected as described below. In the following, the scanning line 3K will be described as an example as necessary.
The same applies to C, 3M, and 3Y.

That is, the photosensitive drum 1a of the image station Pa is driven to rotate in the direction of arrow C by the drive motor 13, as shown in FIG. Then, on the surface of the photosensitive drum 1a having the same peripheral speed (transport speed) as the transport speed (transport speed) of the intermediate transfer belt 7, the contact R between the photosensitive drum 1a and the intermediate transfer belt 7 and the photosensitive member 1 A scanning start point D is set on a straight line passing through the rotation axis of the drum 1a, that is, on the opposite side of the contact point R with the intermediate transfer belt 7 on the photosensitive drum 1a. In the width direction, that is, in the arrow H direction, up to the scanning end point E,
A latent image line e of a black component color is formed by the scanning line 3K.

Similarly, for cyan, magenta, and yellow, the scanning lines 3C and 3C are respectively provided on the photosensitive drum 1b of the image station Pb, the photosensitive drum 1c of the image station Pc, and the photosensitive drum 1d of the image station Pd. 3M, irradiating the scanning line 3Y, the photosensitive drums 1b, 1c,... From the scanning start point D located on the opposite side of the contact point R with the intermediate transfer belt 7 on the photosensitive drum 1a in the direction of arrow H to the scanning end point E. A latent image line e of a cyan component color, a magenta component color, and a yellow component color having a predetermined inclination with respect to the rotation axis of 1d is formed.

After the latent image line e is formed in this manner, black, cyan, magenta and yellow latent image lines are provided by a CCD (not shown) provided on the intermediate transfer belt 7 in a non-contact state. The position of the scanning start point D at e is detected. And the black latent image line e
The scanning start point D of the latent image line e for cyan, magenta, and yellow is made to coincide with the scanning start point D of.

Next, using the above-mentioned CCD, the black, cyan, magenta,
The inclination of the transfer line g for yellow is detected, and the inclination of the transfer line g for each color is corrected by correcting the inclination of the transfer line g for cyan, magenta, and yellow to match the inclination of the transfer line g for black. Match and correct the color shift.

Here, the angle correction of the transfer line g will be described. If the rotation speed of the drive motor 13 is increased to make the peripheral speed of the photosensitive drum 1a faster than the transport speed of the intermediate transfer belt 7 (that is, the reference speed of the photosensitive drum 1a),
Moving from the scanning start point D in the direction of arrow H to the position of the scanning end point F, a latent image line f having a smaller inclination angle than the above-described latent image line e with respect to the rotation axis of the photosensitive drum 1a is formed. . Then, such a latent image line f is visualized by the developing unit 4a and is transferred to the intermediate transfer belt 7 by the transfer unit 5a.

Here, if the peripheral speed of the photosensitive drum 1a is higher than the conveying speed of the intermediate transfer belt 7, the line that visualizes the latent image line f shown in FIG. 2 becomes as shown in FIG. In addition, on the intermediate transfer belt 7, a transfer line g having a smaller inclination angle with respect to the rotation axis of the photosensitive drum 1a than the transfer line f 'when the peripheral speed of the photosensitive drum 1a and the transport speed of the intermediate transfer belt 7 are the same. Becomes If the peripheral speed of the photosensitive drum 1a is made slower than the conveying speed of the intermediate transfer belt 7, the inclination angle of the latent image line and the transfer line with respect to the rotation axis of the photosensitive drum 1a is increased.

Therefore, each photosensitive drum 1a, 1b, 1
The angle of the transfer line g is corrected by adjusting the peripheral speeds c and 1d.

In the present embodiment, as shown in FIG. 2, the exposing means 3 changes the latent image line e formed on the photoreceptor drum 1a by the scanning line 3K irradiated from the exposing means 3. The photosensitive drum 1a is disposed so as to have a predetermined inclination with respect to the rotation axis of the drum 1a.
This is to increase the variation rate of the inclination of the transfer line g on the intermediate transfer belt 7 with respect to the change in the peripheral speed a.

Here, the reason why the rate of change of the inclination becomes large is as follows. That is, when the latent image line f is formed parallel to the rotation axis of the photosensitive drum 1a, the transfer line g is substantially parallel to the rotation axis of the photosensitive drum 1a even when the peripheral speed of the photosensitive drum 1a changes. Will remain. On the other hand, when the latent image line f is formed to be inclined with respect to the rotation axis of the photosensitive drum 1a, the inclination of the transfer line g changes when the peripheral speed of the photosensitive drum 1a changes. Accordingly, the greater the inclination of the latent image line f with respect to the rotation axis of the photosensitive drum 1a, the greater the inclination of the transfer line g on the intermediate transfer belt 7 with respect to the change in the peripheral speed of the photosensitive drum 1a. Because.

Then, the latent image line e is connected to the photosensitive drum 1a.
By forming it with inclination to the rotation axis of
The variation rate of the inclination of the transfer line g on the intermediate transfer belt 7 with respect to the change in the peripheral speed of the photosensitive drum 1a increases. Therefore, by controlling the peripheral speed of the photosensitive drum 1a,
The adjustment of the inclination deviation of the transfer line g can be easily performed at low cost.

As in this embodiment, the latent image line e is moved from the scanning start point D to the arrow H on the surface of the photosensitive drum 1a.
When the scanning end point E at this time is downstream of the rotation direction of the photosensitive drum 1a with respect to the scanning start point D, the photosensitive drum 1a is moved with respect to the reference speed of the photosensitive drum 1a. As for the peripheral speed, the change rate of the inclination of the scanning line 3K on the intermediate transfer belt 7 with respect to the change in the peripheral speed of the photosensitive drum 1a becomes larger as the peripheral speed becomes faster than the peripheral speed.

As shown in FIG. 2, when the peripheral speed of the photosensitive drum 1a is higher than the reference speed of the photosensitive drum 1a, the inclination of the latent image line e with respect to the rotation axis of the photosensitive drum 1a becomes smaller. That is, when the peripheral speed of the photosensitive drum 1a is lower than the reference speed of the photosensitive drum 1a, the inclination of the latent image line e with respect to the rotation axis of the photosensitive drum 1a increases.

As described above, since the scanning end point E is located downstream of the rotation direction of the photosensitive drum 1a with respect to the scanning start point D, the peripheral speed of the photosensitive drum 1a is lower than that of the photosensitive drum 1a. Since the inclination of the transfer image on the transfer belt 7 becomes large, the load torque of the driving source for rotating the photosensitive drum 1a is in a region where the peripheral speed of the photosensitive drum 1a is lower than the reference speed of the photosensitive drum 1a. It is possible to adjust a tilt shift in an oblique direction in a small area, and a high-quality image can be obtained.

Here, the scanning start point D is set to the photosensitive drum 1a.
Is set at a position other than the side opposite to the contact point R with the intermediate transfer belt 7 to adjust the inclination shift, the scanning start point D
Position moves away from or approaches the position opposite to the contact point R with the intermediate transfer belt 7 on the photosensitive drum 1a, so that after the inclination shift is adjusted, the position must be adjusted again. .

On the other hand, as in this embodiment, if the scanning start point D of the photosensitive drum 1a is set at a position on the photosensitive drum 1a opposite to the contact point R with the intermediate transfer belt 7, the scanning start point D is set. Even if the position of the transfer image on the intermediate transfer belt 7 is aligned in the main scanning direction and the sub-scanning direction and then the inclination is adjusted, the position of the scanning start point D does not change. Therefore, the adjustment of the inclination shift can be performed with a small number of times and in a short time.

As shown in FIG. 4, a scanning intermediate point DG which is an intermediate point between the scanning start point D and the scanning end point G is set on the opposite side of the contact point R between the photosensitive drum 1a and the intermediate transfer belt 7. This position may be used as a reference point for adjusting the tilt shift. By doing so, the scanning end point G and the photosensitive drum 1a
, The deviation from the rotation axis becomes small, so that the printing curvature and the depth of focus error on the photosensitive drum 1a constituted by the curved surface can be reduced.

Hereinafter, for the cyan, magenta, and yellow images, the peripheral speeds of the photosensitive drums 1b, 1c, and 1d are adjusted so that the transfer lines have the same inclination. A toner image of four colors is formed.

As described above, according to the multiplex image forming apparatus of the present embodiment, the scanning start point D of the photosensitive drum 1a is set at a position on the photosensitive drum 1a opposite to the contact R with the intermediate transfer belt 7. Then, the peripheral speeds of the photosensitive drums 1a, 1b, 1c, 1d are controlled so that the inclination of the transfer line of each color image is the same, and the inclination deviation is corrected. The displacement of each pixel in the case of superimposition is eliminated, and it is possible to obtain a high-quality image without image deterioration due to scanning unevenness due to the inclination displacement of the scanning lines 3K, 3C, 3M, 3Y.

Further, as described above, the scanning start point D of the photosensitive drum 1a is set to the intermediate transfer belt 7 on the photosensitive drum 1a.
Is set at a position on the opposite side of the contact R with the scanning start point D even when the inclination of the transfer image on the intermediate transfer belt 7 is adjusted in the main scanning direction and the sub-scanning direction and then the inclination is adjusted. Does not change, it is possible to quickly adjust the inclination shift.

If a scanning intermediate point DG between the scanning start point D and the scanning end point G is set on the photosensitive drum 1a on the side opposite to the contact point R with the intermediate transfer belt 7, and the reference point is used as a reference point for adjusting the inclination shift. Since the deviation between the scanning end point G and the rotation axis of the photosensitive drum 1a is reduced, it is possible to reduce the printing curvature and the depth of focus error on the photosensitive drum 1a having a curved surface.

[0055]

As described above, according to the present invention, since the deviation of each pixel when the optical scanning images by the exposure means are superposed is eliminated, the image deterioration caused by the scanning unevenness due to the inclination deviation of the scanning line is eliminated. An effective effect that it is possible to obtain an image with no high quality can be obtained.

If the scanning start point of the photosensitive member is set at a position opposite to the contact point with the intermediate transfer member on the photosensitive member, the position of the transferred image on the intermediate transfer member in the main scanning direction and the sub-scanning direction can be adjusted. Since the position of the scanning start point does not change even if the tilt shift is adjusted after the adjustment, an effective effect that the tilt shift can be promptly adjusted can be obtained.

Further, if the scanning intermediate point of the photosensitive member is set on the opposite side of the contact point between the photosensitive member and the intermediate transfer member, the deviation between the scanning end point and the rotation axis of the photosensitive member is reduced, and the photosensitive member is constituted by a curved surface. An effective effect that it is possible to reduce the print curvature and the depth of focus error on the photoconductor is obtained.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing a relationship between an exposure unit and a photosensitive drum in the multiple image forming apparatus of FIG.

FIG. 3 is an explanatory diagram illustrating an example of a relationship between a photosensitive drum and an intermediate transfer belt in the multiple image forming apparatus in FIG. 1;

FIG. 4 is an explanatory diagram showing another example of the relationship between the photosensitive drum and the intermediate transfer belt in the multiple image forming apparatus of FIG.

FIG. 5 is an explanatory diagram showing types of displacement of a transferred image.

FIG. 6 is a perspective view showing a correction device of a conventional multiple image forming apparatus.

[Explanation of symbols]

 1a Photoconductor drum (photoconductor) 1b Photoconductor drum (photoconductor) 1c Photoconductor drum (photoconductor) 1d Photoconductor drum (photoconductor) 2a Charging means 2b Charging means 2c Charging means 2d Charging means 3 Exposure means 3K Scanning line 3C scanning line 3M scanning line 3Y scanning line 4a developing means 4b developing means 4c developing means 4d developing means 5a transfer means 5b transfer means 5c transfer means 5d transfer means 7 intermediate transfer belt (intermediate transfer body)

Continued on the front page (72) Inventor Junichi Tanizaki 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. ) 2H027 DA17 EB04 EC20 ED02 ED24 EE07 EF09 2H030 AA01 AB02 AD12 BB02 BB12 BB23 BB42

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; A latent image line formed on the photoconductor by irradiating a scanning line corresponding to image data of a specific color is arranged so as to have a predetermined inclination with respect to a rotation axis of the photoconductor, and is statically placed on the photoconductor. Exposure means for forming an electrostatic latent image; a plurality of developing means provided for each of the photoconductors to visualize the electrostatic latent image formed on the photoconductor; provided for each of the photoconductors And a plurality of transfer means for sequentially transferring a single-color image of each color formed on the photoreceptor onto an intermediate transfer member, and a plurality of transfer units are provided on a side of the photoreceptor opposite to a contact point with the intermediate transfer member. From the scanning start point, Developing a latent image line extending to a scanning end point in the direction to control the peripheral speed of each of the photosensitive members so that the inclination of the transfer line transferred to the intermediate transfer member is the same. Forming equipment. 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, A latent image line formed on the photoreceptor by irradiating a scanning line corresponding to image data of a specific color is arranged so as to have a predetermined inclination with respect to a rotation axis of the photoreceptor. An exposure unit for forming a latent image; a plurality of developing units provided for each of the photoconductors to visualize the electrostatic latent image formed on the photoconductor; provided for each of the photoconductors A plurality of transfer means for sequentially superimposing and transferring monochromatic images of each color formed on the photoreceptor onto an intermediate transfer member, wherein a scan set on a side of the photoreceptor opposite to a contact point with the intermediate transfer member From the midpoint, approximately the width of the photoconductor Forming a latent image line extending to the scanning end point and controlling the peripheral speed of each of the photoconductors so that the transfer lines transferred to the intermediate transfer body have the same inclination. apparatus.