JP2003255658A - Photoreceptor drum for tandem type color image forming apparatus, method for disposing it, and tandem type color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoreceptor drum for a tandem type image forming apparatus which is extremely advantageous in obtaining a clear image without having a slippage of image and an image blurring. <P>SOLUTION: Respective photoreceptor drums 6 have diameters D which are mutually the same, and are formed so that the level of deviation in a radial direction by taking a center axis L connecting the centers of the axial supporting parts 1610 and 1810 of first and second flange members 16 and 18 as a reference is set ≤30 μm. Four photoreceptor drums 6 are disposed so that a difference between the angle difference of arbitrary two photoreceptor drums 6 out of four photoreceptor drums 6 in a deviation direction and an angle difference corresponding to a surplus at the time of dividing the axle-to- axle distance of two photoreceptor drums 6 by the peripheral length πD of the photoreceptor drum 6 is within the range of ±45°. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive drum used in a tandem type color image forming apparatus, a method for disposing the photosensitive drum, and a tandem type color image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic apparatus (for example, a copying machine or a printer), factors such as image blurring are caused by processing errors of various components of the image forming apparatus, assembly errors, and image forming apparatus. Examples include vibration and uneven rotation of the photosensitive drum due to the gear transmission system. In order to obtain a clear image, the present inventor has focused on the photosensitive drum itself, which is a main component of the image forming apparatus. That is, the photoconductor drum is composed of a drum main body on which a photosensitive layer is formed and a flange member attached to one end of the drum main body. Then, the image forming is performed so that the photosensitive drum is rotated about a central axis connecting the centers of both the shaft supporting portion provided on the other end of the drum body and the shaft supporting portion provided on the flange member. Disposed in the device. Alternatively, the photosensitive drum includes a drum body and flange members attached to both ends of the drum body,
The photoconductor drum is arranged in the image forming apparatus so as to be rotated about a central axis connecting the centers of the shaft supporting portions of the flange members at both ends of the drum body. When the photosensitive drum is shaken, that is, the photosensitive drum is bent (the photosensitive drum itself is curved) or the axis is displaced (the center of the outer peripheral surface of the photosensitive drum is deviated from the center of rotation).
If there is such a deviation, an image deviation from a position where it should be originally formed occurs during electrostatic latent image formation and transfer due to the shake caused by the bending and the axis deviation.

More specifically, in a laser beam printer or the like that uses a polygon mirror to perform laser scanning, when forming an electrostatic latent image, the laser beam enters obliquely toward the end of the photosensitive drum. Because
When the photoconductor drum is bent or misaligned, the arrival position of the laser beam deviates in the axial direction of the drum, resulting in misalignment in the main scanning direction. Also, if the photosensitive drum is bent or misaligned, the distance from the center of rotation of the photosensitive drum to the surface of the photosensitive drum, that is, the difference in the radius of rotation, causes the exposure of the surface of the photosensitive drum at a small radius of rotation. The electrostatic latent image is clogged because the moving speed with respect to the system becomes slow, and the moving speed of the surface of the photoconductor drum with respect to the exposure system is increased at a portion having a large radius of rotation, and the electrostatic latent image is extended to cause a deviation in the sub-scanning direction.

[0004]

As a result, the printed image is distorted. Particularly, in the case of a color copier called a tandem type, which uses a plurality of photosensitive drums arranged in parallel, for example, the photosensitive drums are arranged for each color of magenta, yellow, cyan, and black, and Since four photoconductor drums are used to form an image, positional deviation and color misregistration become extremely noticeable. If the photoconductor drum is not shaken and is assembled as designed, the above-mentioned problem does not occur, but it is practically impossible to obtain a photoconductor drum having no shake, and as described above, a plurality of This is all the more true in a tandem type image forming apparatus using a photosensitive drum. When focusing only on the photoconductor drum, a clear image cannot be obtained when the amount of shake of the photoconductor drum is large, and a clear image can be obtained when the processing error is within a certain range. Yes, there is no quantitative standard.

As a result, in the prior art, it has been attempted to reduce the assembly error, suppress the vibration of the apparatus, and reduce the rotational unevenness of the photosensitive drum on the assumption that the photosensitive drum has a certain amount of vibration. At present, various measures (for example, Japanese Patent Laid-Open No. 2000-330448) are taken to obtain a clear image from a viewpoint different from that of the photoconductor drum. However, with the recent increase in resolution, the above-mentioned countermeasures are limited in the tandem type image forming apparatus, and some further improvement has been desired. The present invention has been devised in view of the above circumstances,
SUMMARY OF THE INVENTION It is an object of the present invention to provide a tandem-type photosensitive drum for a tandem-type image forming apparatus, a method of disposing the photosensitive drum, and a tandem-type image forming apparatus, which are extremely advantageous in obtaining a clear image without image shift or image blur.

[0006]

In order to achieve the above object, the present invention is directed to a center connecting the centers of axially supporting portions at both ends in the longitudinal direction, which have the same diameter D and have photosensitive layers formed on their outer peripheral surfaces. In a photoconductor drum for a tandem type color image forming apparatus, in which a plurality of photoconductor drums that are rotated about an axis are arranged in parallel to each other, the plurality of photoconductor drums are based on the respective central axes. Is formed to have a radial deflection of 30 μm or less,
Further, the angular difference between the shake directions of any two photoconductor drums of the plurality of photoconductor drums and the axial distance S between the two photoconductor drums are divided by the circumferential length πD of the photoconductor drums. The plurality of photoconductor drums are arranged such that the difference between them and the angular difference corresponding to the surplus falls within a range of ± 45 degrees. Further, the present invention provides a plurality of photosensitive drums having the same diameter D and having photosensitive layers formed on their outer peripheral surfaces and having a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction as a rotation center. However, in the tandem type color image forming apparatus photoconductor drums arranged in parallel to each other, the plurality of photoconductor drums have a difference in radial deviation of 30 μm with respect to each central axis. It is formed so as to fall within the following range, and further, the angular difference between the shake directions of any two photoconductor drums among the plurality of photoconductor drums, and the axial distance S between the two photoconductor drums. The plurality of photosensitive drums are arranged such that the difference between the angle difference corresponding to the remainder obtained by dividing by the peripheral length πD of the photosensitive drum falls within a range of ± 45 degrees. And Further, the present invention provides a plurality of photosensitive drums having the same diameter D and having photosensitive layers formed on their outer peripheral surfaces and having a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction as a rotation center. However, in the tandem-type color image forming apparatus arranged in parallel to each other, the plurality of photoconductor drums are formed such that the magnitude of the radial deflection with respect to the central axis is 30 μm or less. Further, the difference in angle between the shake directions of any two photosensitive drums among the plurality of photosensitive drums, and
The distance S between the axes of the photoconductor drums is the peripheral length π of the photoconductor drum.
The difference from the angular difference corresponding to the remainder when divided by D is ±
It is characterized in that it is arranged so as to fall within a range of 45 degrees. Further, the present invention provides a plurality of photosensitive drums having the same diameter D and having photosensitive layers formed on their outer peripheral surfaces and having a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction as a rotation center. However, in the tandem type color image forming apparatus arranged in parallel to each other, the plurality of photoconductor drums have a difference in the magnitude of radial shake with respect to the central axis of each of the plurality of photoconductor drums within a range of 30 μm or less. Further, the photosensitive drum is formed such that the angular difference between the shake directions of any two photosensitive drums among the plurality of photosensitive drums and the axial distance S between these two photosensitive drums are determined. The difference from the angular difference corresponding to the remainder when divided by the perimeter πD of
It is characterized in that it is arranged so as to fall within a range of ± 45 degrees. Further, in the present invention, in the tandem type color image forming apparatus, the center axis connecting the centers of the axially supporting portions at both ends in the longitudinal direction having the same diameter D and having the photosensitive layers formed on the respective outer peripheral surfaces is the center of rotation. When arranging a plurality of rotated photoconductor drums in parallel with each other, a plurality of photoconductor drums having a radial deflection of 30 μm or less with respect to the central axis are prepared, and the plurality of photoconductor drums are provided. The body drum is provided with a mark indicating the direction of radial deflection with respect to each of the central axes at a location visible from the outside, and while visually recognizing the mark, any one of the plurality of photosensitive drums is provided. Between the angular difference in the shake direction of the two photosensitive drums and the angular difference corresponding to the surplus when the axial distance S of the two photosensitive drums is divided by the peripheral length πD of the photosensitive drums. Difference is within ± 45 degrees Wherein the urchin was to disposing the plurality of photosensitive drums. Further, in the present invention, in the tandem type color image forming apparatus, the center axis connecting the centers of the axially supporting portions at both ends in the longitudinal direction having the same diameter D and having the photosensitive layers formed on the respective outer peripheral surfaces is the center of rotation. When arranging a plurality of rotated photoconductor drums in parallel with each other, a plurality of photoconductor drums having a difference in the magnitude of radial deflection with respect to the central axis within a range of 30 μm or less are prepared in advance. The plurality of photoconductor drums are provided with marks indicating the direction of radial deflection with respect to the central axes of the plurality of photoconductor drums at locations visible from the outside, and the plurality of photoconductors are provided while visually recognizing the marks. It corresponds to the angular difference in the direction of shake of any two photosensitive drums of the drum and the surplus when the axial distance S of these two photosensitive drums is divided by the peripheral length πD of the photosensitive drums. The difference between the angle difference is ± 45 Characterized in that the plurality of photosensitive drums and so arranged as fall within the scope of the.

According to the present invention, it is extremely advantageous in obtaining a clear image without image shift or image blur in a tandem type color image forming apparatus. Further, according to the method of disposing the photoconductor drum of the present invention, it is possible to easily and surely assemble the tandem type color image forming apparatus that can obtain a clear image without image shift or image blur.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a photosensitive drum for a tandem type color image forming apparatus, a method of disposing the photosensitive drum and a tandem type color image forming apparatus according to the present invention will be described below. FIG. 1 is a schematic view of a tandem type color image forming apparatus. The tandem type color image forming apparatus 2 includes a developing unit 4, a photosensitive drum (electrophotographic photosensitive member) 6, an optical unit (exposure device) 8, a paper feeding device (not shown), and a paper A.
A conveyor belt 10 for conveying (recording medium) is provided,
Four photoconductor drums 6 are provided corresponding to each color of magenta, yellow, cyan, and black.
Is also provided for each of the photosensitive drums 6.
The sheet feeding device feeds the sheet A onto the conveyor belt 10.
The conveyor belt 10 conveys the sheet A, and the four photoconductor drums 6 are arranged along the conveyor belt 10. The photosensitive drums 6 are parallel to each other, extend in a direction orthogonal to the transport direction of the transport belt 10, and are arranged so as to sandwich the transport belt 10 in cooperation with the transfer roller 610. Each of the developing units 4 has a charger 40.
2, a developing device 404, a fixing device 406, a static eliminator 408, and a cleaner 410. The charger 402
Is to impart photosensitivity by uniformly charging the surface of the photoconductor drum 6. As the charger 402, a corotron, a scorotron, a charging roller or the like is used. The optical unit 8 irradiates, for example, a laser beam modulated by data sent from a computer to scan the surface of the photosensitive drum 6 which is uniformly charged. Photoconductor drum 6
An electrostatic latent image is formed by removing the charges in the upper portion.

Subsequently, the developing unit 404 develops the electrostatic latent image with toner, and a visible image is formed on the photosensitive drum 6. Then, the sheet A is superposed on the visible image, the toner forming the visible image is transferred from the photosensitive drum 6 to the sheet A, and the transferred toner is heated and pressed, The sheet A is fused and formed into a permanent image. On the other hand, the latent image charges on the photosensitive drum 6 after the transfer are removed by the static eliminator 408, and the residual toner remaining on the photosensitive drum 6 without being transferred is removed by the cleaner 410. Then, the above-described image forming process is performed for each photoconductor drum 6 corresponding to each color of magenta, yellow, cyan, and black, and a color image is formed on the sheet A.

FIG. 2A is a front view of the photosensitive drum, and FIG. 2B is an exploded view of the photosensitive drum. As shown in FIG. 1, each photosensitive drum 6 includes a drum body 14, first and second flange members 16 concentrically attached to the drum body 14 at both ends in the longitudinal direction of the drum body 14. It is composed of 18 and. The drum body 14 is composed of a cylindrical body 1402 and a photosensitive layer 1404 formed on the surface of the cylindrical body 1402, and the fitting holes 14 are formed at both ends of the cylindrical body 1402.
06 is formed.

The first flange member 16 has a cylindrical portion 1602 fitted and fixed in a fitting hole 1406 at one end of the drum body 14, and a large diameter portion 160 having a larger diameter than the cylindrical portion 1602.
4 and a shaft supporting portion 1610, the second flange member 18 is a tubular portion 1802 fitted and fixed in a fitting hole 1406 at the other end of the drum body 14, and the tubular portion 1802 is at one end of the drum body 14. The gear 1 provided so as to be adjacent to the end of the drum body 14 while being fitted and fixed in the
804 and a shaft support portion 1810. The arrangement of each photoconductor drum 6 in the image forming apparatus is performed by rotatably supporting the shaft supporting portions 1610 and 1810 of the first and second flange members 16 and 18 on the frame side of the image forming apparatus. When the shaft supporting portions 1610 and 1810 of the first and second flange members 16 and 18 are shaft-shaped, the shaft supporting portions 1610 and 1810 are rotatably supported in the bearing holes of the frame, or the shaft supporting portion 16 is provided.
When the holes 10 and 1810 are hole-shaped, they are rotatably supported by the shaft on the frame side. In the present embodiment,
The shaft support portions 1610 and 1810 are formed by bearing holes. In the present embodiment, as shown in FIG.
A driving gear 20 and a driven gear 22 mesh with 604 and 1804, and the photoconductor drum 6 is rotationally driven about the central axis L connecting the centers of the shaft supporting portions 1610 and 1810 via the gears 20, 1604, 1804 and 22. At the same time, the photosensitive drum 6 is arranged so as to also function as a power transmission member for driving force.

In the present embodiment, each photosensitive drum 6
Have the same diameter D as each other, and the magnitude of radial runout is 30 with respect to the central axis L connecting the centers of the shaft supporting portions 1610, 1810 of the first and second flange members 16, 18.
It is formed so as to be less than or equal to μm. Alternatively, in the present embodiment, the respective photosensitive drums 6 have the same diameter D as each other, and the first and second flange members 16, 18 are also provided.
It is formed so that the difference in the magnitude of radial runout with respect to the central axis L connecting the centers of the shaft supporting portions 1610 and 1810 is 30 μm or less. The measurement of such shake is performed in JP-A-2002-48530 and JP-A-2002-49279.
Various methods known in the related art such as No. etc. can be adopted. That is, the measurement of the magnitude and direction of the shake is, for example,
The photoconductor drum 6 is supported by extending in the horizontal direction, and the photoconductor drum 6 is rotated with reference to the shaft support portions (bearing holes) 1610 and 1810 at both ends, and a distance sensor (for example, a laser Using an interferometer), a displacement sensor (for example, a scanning laser displacement meter), an encoder or the like for measuring the shake direction, and using various conventionally known high-precision measuring devices. In the present invention, the radial runout refers to a maximum runout value measured at an arbitrary position (corresponding to “total runout” in JIS).

Further, the angular difference between the shake directions of any two photoconductor drums 6 among the four photoconductor drums 6 and the axial distance between the two photoconductor drums 6 are defined as the photoconductor drums. The four photoconductor drums 6 are arranged such that the difference between the angle difference corresponding to the remainder when divided by the peripheral length πD of 6 is within ± 45 degrees. At the time of measuring the shake, a position outside the image forming area, such as a position of the first flange member 16 or the second flange member 18 at a position where the direction of the shake exists (the direction of the largest shake) is externally applied. If a visible mark is provided, the photosensitive drum 6 can be easily arranged while looking at this mark. That is,
Since the axial distance of the photoconductor drums 6, that is, the assembling position is set in advance, the photoconductor drums 6 can be arranged while visually recognizing the shake direction by looking at the mark, and the four photoconductor drums 6 can be arranged. Any two of the photoconductor drums 6
Difference in the direction of shake of the two photosensitive drums 6
The four photoconductor drums 6 are arranged such that the difference between the inter-axis distance S and the angular difference corresponding to the surplus when divided by the circumferential length πD of the photoconductor drums 6 is within ± 45 degrees. The installation work is simplified. The mark in this case may be painted or the like, or may be uneven.

Next, the operation and effect of this embodiment will be described. FIG. 4 is an explanatory diagram of the positional relationship between the two photoconductor drums when the image shift is minimized. FIG. 4 shows two arbitrary photoconductor drums out of the four photoconductor drums 6, and the two photoconductor drums 6 are the first and second photoconductor drums, respectively.
Shaft support portions 1610 and 181 of the second flange members 16 and 18
It is driven to rotate about a central axis L connecting the centers of 0, and the magnitudes of radial shakes with respect to the central axes L of the two photosensitive drums 6 are d1 and d2, respectively.
The axial distance S between the two photosensitive drums 6 is set to S = 2nπD, where n is a natural number. Where 2
The direction of radial runout is aligned with respect to the central axis L of the photoconductor drum 6 of the book. More specifically, the surplus when the angular difference between the two photoconductor drums 6 in the shake direction and the axial distance S between the two photoconductor drums 6 is divided by the circumferential length πD of the photoconductor drums 6, Try to be near zero, i.e. zero or close to zero.

Therefore, if it is assumed that the image is transferred onto the sheet at a location 602 directly below the radial center of the outer peripheral surface of the photosensitive drum 6, a color shift of d1-d2 occurs. Further, assuming that the diameter of the photosensitive drum is D, the radius of the transfer roller is r, and the image is transferred to the paper at the closest contact point 604 with the transfer roller, (d1-d2).
A color shift of r / (R + r) occurs. That is, if the magnitudes of shakes d1 and d2 are approximately the same and the directions of shakes are aligned, in other words, the angular difference between the shake directions of the two photoconductor drums 6 and the two photoconductor drums 6 are detected. Axis distance S
If the remainder when dividing by the peripheral length πD of the photoconductor drum 6 is almost zero, it is possible to reduce the color misregistration even when the shake of the photoconductor drum 6 is large.

Contrary to this, the phase of the radial deflection with respect to the central axes L of the two photosensitive drums 6 is 180.
In the case of offsetting, more specifically, the angular difference between the two photoconductor drums 6 in the shake direction and the axial distance S between the two photoconductor drums 6 are defined by the circumferential length πD of the photoconductor drums. If the difference between the angle difference corresponding to the remainder when dividing is 180 degrees,
The image shift is maximum. FIG. 5 is an explanatory diagram of the positional relationship between the two photoconductor drums when the image shift is maximum.
In FIG. 5, the magnitudes of radial runouts based on the central axis L of the two photoconductor drums 6 are d1 and d2, respectively, and the axial distance S between the two photoconductor drums 6 is n. As a natural number, S = 2nπD is set. Here, the phase of the radial shake direction with respect to the central axes L of the two photoconductor drums 6 is shifted by 180 degrees. More specifically, the angular difference between the shake directions of the two photoconductor drums 6 and the axial distance S between the two photoconductor drums 6 are determined by the circumferential length πD of the photoconductor drums.
The difference between the angle difference corresponding to the remainder when divided by 180 is
Make sure that it happens.

Therefore, if it is assumed that the image is transferred onto the sheet at a location 602 just below the radial center of the outer peripheral surface of the photosensitive drum 6, a color shift of d1 + d2 occurs. Further, assuming that the diameter of the photosensitive drum is D, the radius of the transfer roller is r, and it is assumed that the image is transferred to the paper at the closest contact point 604 with the transfer roller, (d1 + d2) · r /
A color shift of (R + r) occurs. That is, the color shift is 2
The shake magnitudes d1 and d2 of the photoconductor drum 6 of the book increase in proportion to the added value.

As shown in Table 1, the present inventors have found that the outer diameter is 3
0 mm, the length is 340 mm, and the radial runout magnitude with respect to the central axis L is 13 μm, 22 μm, 31 μm,
Six photoconductor drums 6 of 41 μm, 53 μm, and 64 μm
(No. 1, No. 2, No. 3, No. 4, No.
5, No. An image shift test was performed by combining two of 6). In addition, the magnitude of the radial deflection of the photoconductor drum 6 is based on the axial support portions (bearing holes) 1610 and 1810 of the first and second flange members 16 and 18 at both ends as a reference. It was measured.

[0019]

[Table 1]

In the image shift test, these two photoconductor drums were assembled for a magenta and cyan photoconductor drum of a tandem type color printer, fine halftone dots were output, and the image was fed at the center of the image. The color shift in the direction was observed with an optical microscope. The degree of color misregistration was a relative evaluation between samples, and was evaluated in four grades of ⊚, ◯, Δ, and ×. The test results are shown in Table 2.

[0021]

[Table 2]

The view of Table 2 is as follows. For example,
In the column A of Table 2, No. in which the shake amount is 13 μm. No. 1 with the photosensitive drum 6 of No. 1 and the swing amount of 22 μm. This is the case where the second photosensitive drum 6 is used. In this case, from a different point of view, the difference between the radial runouts of these photosensitive drums 6 is 22 μm−13 μm = 9 μm. Therefore, the column A in Table 2 shows that the radial runout difference is 9 μm. This also applies when two photoconductor drums 6 are used. Column A corresponds to the angular difference in the direction of shake of these two photoconductor drums 6 and the surplus when the axial distance S of these two photoconductor drums 6 is divided by the peripheral length πD of the photoconductor drums. Angle difference is 0 degree, 4
In the case of 5 degrees and 90 degrees, a good image with a slight color shift was obtained, and the evaluation was ⊚. Further, when the angle difference was 135 degrees, although the color shift was a little large, a good image was still obtained and was evaluated as ◯. The angle difference is 18
In the case of 0 degree, the color shift was a little large and the image was not good, and was evaluated as Δ. In addition, for example, in the column M of Table 2, No. in which the shake amount is 13 μm. No. 1 with the photosensitive drum 6 of No. 1 and a shake amount of 53 μm. This is the case where the photosensitive drum 6 of No. 5 is used. In this case, if the viewpoint is changed, the difference between the radial shakes of the photoconductor drums 6 is 53.
Since μm−13 μm = 40 μm, column M in Table 2 is also the case where two photoconductor drums 6 having a radial runout difference of 40 μm are used. In column M, the angular difference between the shake directions of these two photoconductor drums 6 and the axial distance S between these two photoconductor drums 6 are indicated by the circumferential length πD of the photoconductor drums.
When the angle difference corresponding to the remainder when divided by 0 is 0 degree, the color shift is slightly large and the image cannot be said to be good, and is evaluated as Δ. Further, in the case of 45 degrees, 90 degrees, 135 degrees, and 180 degrees, the image was greatly deteriorated and the image was inferior, and was evaluated as x.

As is clear from columns A, B, C, F, G, and J of Table 2, when the photosensitive drum 6 having a radial deflection of 40 μm or less is used, two photosensitive drums are used. The difference between the angular difference in the shake direction of 6 and the angular difference corresponding to the surplus when the axial distance S of the two photosensitive drums 6 is divided by the peripheral length πD of the photosensitive drums is zero. Of course, if
Even if it is not zero, a good image can be obtained if it is within the range of ± 45 degrees. Further, as shown in columns A and B, when the photosensitive drum 6 having a shake amount of 31 μm or less is used,
Even if the difference is not zero, a good image can be obtained within the range of ± 90 degrees. In addition, D, E, H of Table 2
As is clear from I, K to O, when the photosensitive drum 6 having a radial deflection of 53 μm or more is used, the angular difference between the deflection directions of the two photosensitive drums 6 and the two The distance S between the axes of the photosensitive drum 6 is
Even if the difference between the angular difference corresponding to the remainder when divided by D is set to zero, a good image may not be obtained in some cases.

Therefore, the size of the radial runout is 40 μm.
When the photosensitive drum 6 of m or less is used, the angular difference between the shake directions of the two photosensitive drums 6 and the axial distance S between the two photosensitive drums 6 are set to be the circumference of the photosensitive drums. Long πD
A good image is obtained if the difference between the angular difference corresponding to the remainder when divided by is set to zero. actually,
In many cases, LEDs are used as the light source. In that case, blurring of dots due to defocusing of the lens that condenses each LED cell also affects the resolution, so it is necessary to suppress shake of the photosensitive drum 6 alone to some extent. Become. For this reason, when the photosensitive drums 6 having a radial deflection of 30 μm or less are used, the two photosensitive drums 6 are
Difference in the direction of shake of the two photosensitive drums 6
When the difference between the axial distance S and the angular difference corresponding to the remainder when the peripheral length πD of the photosensitive drum is divided is set to zero, a good image is obtained.

Further, the view of Table 2 is changed as follows. As is clear from columns A and B of Table 2, when the difference in the magnitude of shake between the two photoconductor drums 6 used is 9 μm, the difference between the two photoconductor drums 6 in the direction of the shake is Of course, when the angular difference corresponding to the surplus when the axial distance S of these two photosensitive drums 6 is divided by the peripheral length πD of the photosensitive drums is 0 degrees, this angular difference is 45 degrees or Even at 90 °, a good image with a rating of ⊚ can be obtained. Also,
As is clear from columns C to K of Table 2, when the difference in the magnitude of the shake between the two photosensitive drums 6 is 10 μm, 12 μ
m, 11 μm, 18 μm, 19 μm
In case of 18 μm, in case of 23 μm, in case of 28 μm,
In the case of 31 μm, there is a surplus when the angular difference between the shake directions of the two photoconductor drums 6 and the axial distance S of these two photoconductor drums 6 are divided by the circumferential length πD of the photoconductor drums. Of course, when the corresponding angle difference was 0 degree, there was a case where a good image with a rating of ⊚ was obtained even when the angle difference was 45 degrees. Further, as is clear from the columns L to O in Table 2,
The difference in the amount of shake between the two photosensitive drums 6 is 33 μm,
In the case of 40 μm, 42 μm, and 51 μm, the angular difference between the two photoconductor drums 6 in the shake direction and the axial distance S between these two photoconductor drums 6 were divided by the circumferential length πD of the photoconductor drums. Even when the angle difference corresponding to the remainder is 0 degree,
Only images that were evaluated as ◯, Δ, and x were obtained, and good images that were evaluated as ⊚ were not obtained.

Therefore, as is clear from Table 2, 2
When the difference in the size of the radial shake of the two photoconductor drums 6 is 30 μm or less, the angular difference between the two photoconductor drums 6 in the shake direction and The distance S between the axes of the photoconductor drums 6 is set to
A good image is obtained if the difference between the angular difference corresponding to the remainder when divided by is set to zero. Also, A to C
As shown in the columns, columns E to G, and column J, when the difference in the magnitude of shake is 30 μm or less, the difference is ± 45 even if the difference is not zero.
If it is within the range of degrees, a good image can be obtained. Furthermore, as shown in columns A and B, the difference in the size of the shake is 9 μm.
In the following cases, a good image can be obtained if the difference is not zero but within the range of ± 90 degrees.

The photosensitive drum 6 used in the present invention is obtained as follows. (1) The magnitude of the radial runout with respect to the fitting hole 1406 of the drum body 14 is the cylindrical portion 1602 of the first flange member 16 or the second flange member 18 with respect to the shaft support portions 1610, 1810. In the case where the outer peripheral surface of 1802 is sufficiently larger than the radial runout, in this case, the first flange member 16 or the second flange member 18 is set so that the direction of the runout is the radial runout of the drum body 14. The tube portions 1602 and 1802 are fitted and fixed in the fitting hole 1406 so that the directions are opposite to each other, that is, the shakes cancel each other out. (2) When the size of the radial runout with respect to the fitting hole 1406 of the drum main body 14 is relatively small In this case, the first flange member 16 or the second flange member 18 is set in the direction of those runouts. The cylinder parts 1602 and 1802 are fitted into the fitting hole 1406 in such a manner that the direction is the same as the radial deflection direction of the drum body 14, that is, the deflection is added to clarify the deflection direction. And fix it.

(3) When the radial deviation of the first flange member 16 or the second flange member 18 is large In this case, the first flange member 16 or the second flange member 18 is moved in the radial direction. The ranks are preliminarily classified according to the magnitude of the runout, and the first flange member 16 or the second flange member 18 is set in accordance with the above cases (1) and (2) so that the direction of the runout is the diameter of the drum body 14. The cylindrical portions 1602, 18 are fitted in the fitting hole 1406 so that the direction of the runout is opposite to the direction of the runout, or the direction of the runout is the same as the direction of the runout in the radial direction of the drum body.
It is possible to fit and fix 02 to obtain the photosensitive drum 6 in which the magnitude of the shake is specified in a narrow range.

(4) When the radial runout of the first flange member 16 or the second flange member 18 is sufficiently small In this case, the drum body 14 is preliminarily set to the radial runout size. By classifying the ranks and using the drum main body 14 having a small shake amount, it is possible to keep the shake amount of the obtained photosensitive drum 6 within a specific range. In this case, by using a plurality of shake measurement sites, it is possible to perform finer rank division, that is, it is possible to finely adjust the bending amount. It should be noted that the measurement of the magnitude and direction of the shake of the drum body 14 is performed by various conventionally known methods as in the case of measuring the magnitude and the direction of shake of the photosensitive drum 14 described above. The measurement of the magnitude and direction of the radial deflection of the 2 flange member 18 is performed by the first flange member 1
Similar to the case where the magnitude and direction of the shake of the photosensitive drum 14 is measured by supporting the sixth to second flange members 18 in a cantilever manner, various conventionally known methods are used.

The present inventor conducted a test for the case (2) above. That is, the fitting hole 1 of the drum body 14
When the magnitude of the radial runout relative to 406 is relatively small, the first flange member 16 and the second flange member 18 have the same runout direction as the radial runout direction of the drum body 14. Fitting hole 14 so that it faces
A test was carried out to obtain the photoconductor drum 6 in which the cylindrical parts 1602 and 1802 were fitted and fixed to 06.

In this test, the outer diameter was 20 mm and the length was 25 mm.
A cylindrical portion 16 fitted to both sides of a drum body 14 made of aluminum alloy having a thickness of 0 mm and a fitting portion thickness of 0.75 mm at both ends.
The length of the drum body 14 measured using the first flange member 16 and the second flange member 18 made of synthetic resin having the bearing holes 1610 and 1810 having the diameters of 02 and 1802 of 8 mm and the fitting holes 1406 at both ends as a reference. Direction of the maximum radial runout of the central portion of the direction and the bearing holes 1610, 1
1st flange member 1 measured by a perfect circle meter according to 810 standard
6 and the cylindrical portions 1602, 1802 of the second flange member 18 are combined so that the magnitude of the deflection matches the maximum direction to obtain the photoconductor drum 6, and the bearing holes 1610, 18 at both ends are provided.
The magnitude of the radial runout of the central portion of the photoconductor drum 6 with 10 as the reference is measured, and the location of the maximum radial runout of the drum body 14 is set to 0 degrees. The maximum size of the radial runout of No. 6 was also measured. The measurement results are shown in Table 3.

[0032]

[Table 3]

As shown in Table 3, the drum body 14 has an average value of the radial runout of 11.8 μm.
When the magnitude of the radial runout is relatively small, the first flange member 16 and the second flange member 18 are arranged so that their runout directions are the same as the radial runout direction of the drum body 14. When the photosensitive drum 6 is obtained by fixing the drum body 14 to both ends of the drum body 14, the shake is added, and the average value of the shake of the drum body 14 is 1
While the average value of the shake amount of the obtained photosensitive drum 6 is 16.2 μm, which is 1.8 μm, the value becomes slightly large, but the shake direction becomes clear. In this case, the shake direction of the photosensitive drum 6 is −0.4 degrees, which is substantially the same as the shake direction of the drum body 14.

Photosensitive drum 6 used in the present invention
The (drum body 14) is not particularly limited as long as it can be used as a photosensitive drum, but specifically, aluminum or an aluminum alloy, a metal material such as stainless steel, copper or nickel, and aluminum on the surface thereof. Insulating substrates such as polyester film, paper and glass provided with a conductive layer such as copper, palladium, tin oxide and indium oxide are used. When a non-conductor is used, it is generally conducted by blending a conductive powder or by conducting metal deposition on the surface. A drum made of aluminum or aluminum alloy is preferable. The drum may have any shape as long as flanges can be attached to both ends (including fitting and bonding), but a cylindrical drum is generally used.

The case of using cylindrical aluminum or aluminum alloy as the drum will be described below. Aluminum or A1050, A3003, A
After processing aluminum alloy such as 6063 into a cylindrical shape by a porthole method, a mandrel method, etc., in order to obtain a cylinder having a predetermined wall thickness, length and outer diameter, processing such as drawing or cutting is performed. . Further, in order to prevent uneven density, the drum surface may be finished to have a specific surface roughness by utilizing cutting.

The photosensitive drum 6 used in the present invention has a photosensitive layer on the drum body 14. The photosensitive layer may be formed as it is, but it is preferable to form the photosensitive layer on the blocking layer in order to prevent uneven density. Here, the blocking layer refers to an anodic oxide coating, an undercoat layer, or the like.

The anodized film is formed by anodizing the surface of the drum body 14. Before performing anodizing treatment, it is preferable to perform degreasing treatment by various degreasing cleaning methods such as acid, alkali, organic solvent, surfactant, emulsion and electrolysis. Anodized film is a normal method,
For example, it is formed by anodizing treatment in an acidic bath of chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the best result. In the case of anodizing treatment in sulfuric acid, the sulfuric acid concentration is 100 to 300 g / l, the dissolved aluminum concentration is 2 to
15g / l, liquid temperature is 0 to 30 ° C, electrolysis voltage is 10 to 20
The V and the current density are preferably set within the range of 0.5 to 2 A / dm2, but the present invention is not limited to this. The film thickness of the anodized film thus formed is
Usually 20 μm or less, preferably 10 μm or less,
More preferably, it is 7 μm or less.

The drum body 14 that has been anodized can be subjected to a sealing treatment and a dyeing treatment. The sealing treatment is a step of sealing by growing aluminum hydroxide or the like in the porous layer. The sealing treatment method may be an ordinary method, but is preferably performed by immersing it in a solution containing nickel ions (eg, a solution containing nickel acetate or a solution containing nickel fluoride). When the dyeing treatment is performed, the drum body 14 is immersed in an organic or inorganic compound salt solution to adsorb those salts. Specifically, water-soluble organic dyes such as azo type 1 to 10 g / l, liquid temperature 20 to 60 ° C., pH 3 to
9. Immersion time 1 to 20 minutes.

As the subbing layer, organic layers such as polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide and polyamide can be used. Above all, it has excellent adhesion to the drum body 14,
A polyamide resin having low solubility in the solvent used in the charge generation layer coating solution is preferable. It is effective to incorporate fine particles of metal oxides such as alumina and titania and organic or inorganic pigments into the undercoat layer. The thickness of the undercoat layer is usually 0.1 to 10 μm, preferably 0.2 to 5 μm.
Is. In the present invention, anodizing treatment, sealing treatment,
It is also possible to form an undercoat layer on the surface of which the dyeing treatment has been performed.

A photosensitive layer is formed on the drum body 14. The photosensitive layer is one in which a charge generation layer containing a charge generation substance and a charge transport layer are laminated in this order, or those laminated in the reverse order,
Alternatively, a so-called single layer type in which particles of a charge generating substance are dispersed in a charge transporting medium can be used, but a laminated type photosensitive layer having a charge generating layer and a charge transporting layer is preferable. When the photosensitive layer has a single-layer structure, a known material in which a photosensitive material is dispersed in a binder material is used. For example, dye-sensitized ZnO. Examples thereof include a photosensitive layer, a CdS photosensitive layer, and a photosensitive layer in which a charge generating substance is dispersed in a charge transporting substance.

The charge generating layer contains a charge generating substance and a binder resin. The charge generating substance is not particularly limited as long as it is a substance used for an electrophotographic photoreceptor, and specifically, selenium and its alloys, arsenic-selenium, cadmium sulfide, zinc oxide, and other inorganic photoconductors. Organic pigments such as phthalocyanine, azo, quinacridone, polycyclic quinone, perylene, indigo, and benzimidazole can be used. In particular, copper, indium chloride, potassium chloride, tin, oxytitanium, zinc, phthalocyanine pigments such as vanadium, or its oxide or chloride coordinated phthalocyanines, such as metal-free phthalocyanines, or monoazo, bisazo, Trisazo,
Azo pigments such as polyazos are preferred. Of these, phthalocyanine pigments are particularly preferable, and oxytitanium phthalocyanine having a specific crystal system is particularly preferable.
This is because oxytitanium phthalocyanine is more likely to undergo thermal crystal conversion than ordinary pigments.

Examples of such oxytitanium phthalocyanine include those which show a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in X-ray diffraction by CuKα ray, but are not limited thereto. It is not something that will be done. The crystal form of this oxytitanium phthalocyanine is generally called Y type or D type. For example, FIG. 2 of JP-A-62-67094 (referred to as II type in the same publication). JP-A-2-8256
FIG. 1 of Japanese Patent Laid-Open No. 64-82045, No. 1 of Japanese Patent Laid-Open No. 64-82045
Fig., Electrophotographic Society Journal, Vol. 92 (published in 1990), No. 3, pages 250 to 258 (referred to as Y type in the same publication). This crystalline oxytitanium phthalocyanine is characterized by showing a maximum diffraction peak at 27.3 °, but in addition to this, it is usually 7.4 ° or 9.
It shows peaks at 7 ° and 24.2 °.

The intensity of the diffraction peak may change depending on the crystallinity, the orientation of the sample and the measuring method, but in the measurement by the Bragg-Brentano concentration method which is usually used when X-ray diffraction of powder crystals is performed, The above crystalline oxytitanium phthalocyanine has a maximum diffraction peak at 27.3 °. Further, when measured by a thin film optical system (generally called thin film method or parallel method), the maximum diffraction peak may not be 27.3 ° depending on the state of the sample. It is thought that this is due to the orientation.

The dispersion medium is not particularly limited as long as it is used in the manufacturing process of the electrophotographic photosensitive member, and various solvents may be used. For example, diethyl ether, dimethoxyethane, tetrahydrofuran, 1,2-
Ethers such as dimethoxyethane; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as methyl acetate and ethyl acetate; alcohols such as methanol, ethanol and propanol; aromatic hydrocarbons such as toluene and xylene, or 2 A mixture of two or more species can be used. The amount of the dispersion medium used may be any amount as long as the dispersion can be sufficiently performed and the effective amount of the charge generating substance is contained in the dispersion liquid, and the concentration of the charge generating substance in the dispersion liquid at the time of dispersion is usually 3 to 20 wt. %, More preferably about 4 to 20 wt%.

The binder resin is not particularly limited as long as it is used for an electrophotographic photoreceptor, but specifically, polyvinyl butyral, polyvinyl acetal, polyester, polycarbonate, polystyrene, polyester carbonate, polysulfone. , Vinyl polymers such as polyimide, polymethylmethacrylate, and polyvinyl chloride, and their copolymers, phenoxy, epoxy, silicone resins and the like, and partially cross-linked cured products thereof can be used alone or in combination of two or more. As a method of mixing the binder resin and the charge generating substance, for example,
The charge generation material is dispersed in the binder resin powder in the dispersion treatment step, or the polymer solution is added and dispersed at the same time, the dispersion obtained in the dispersion treatment step is mixed with the polymer solution of the binder resin, or conversely dispersed. Any method such as a method of mixing the polymer solution in the liquid may be used.

Next, the dispersion liquid obtained here may be diluted with various solvents in order to obtain liquid properties suitable for coating. As such a solvent, for example, the solvents exemplified as the dispersion medium can be used. The ratio of the charge generating substance to the binder resin is not particularly limited, but generally the charge generating substance is used in the range of 5 to 500 parts by weight with respect to 100 parts by weight of the resin. If necessary, a charge transport material can be included. Examples of the charge transport material include organic polymer compounds such as polyvinylcarbazole, polyvinylpyrene, and polyacenaphthylene,
Electron-withdrawing substances such as fluorenone derivatives, tetracyanoxydimethane, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, diphenoquinone derivatives,
Heterocyclic compounds such as carbazole, indole, imidazole, oxazole, pyrazole, oxadiazole, pyrazoline, and thiadiazole, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, or groups consisting of these compounds in the main chain or side chain. And electron-donating substances such as polymers.
The ratio of the charge transport material to the binder resin is 5 to 500 parts by weight based on 100 parts by weight of the binder resin.

Using the dispersion liquid thus prepared,
A charge generation layer is formed on the drum main body 14 after cutting, or on the drum main body 14 on which an undercoat layer or an anodic oxide coating is formed, and a charge transport layer is laminated thereon to form a photosensitive layer, or A charge transport layer is formed on the drum body 14 and a charge generation layer is formed thereon using the dispersion liquid to form a photosensitive layer, or a charge generation layer is formed on the drum body 14 using the dispersion liquid. The photosensitive layer can be formed by any one of the above structures. The thickness of the charge generation layer is preferably in the range of 0.1 to 10 μm when the photosensitive layer is laminated with the charge transport layer, and the thickness of the charge transport layer is preferably 10 to 40 μm. When the photosensitive layer is formed with a single layer structure, the thickness of the photosensitive layer is preferably in the range of 5 to 40 μm.

The charge transport layer is mixed with a known polymer having excellent performance as a binder resin on the above charge generation layer and dissolved in a suitable solvent together with the charge transport substance.
It can be produced by applying an electron-withdrawing compound, or a plasticizer, a pigment and other additives as necessary, and applying a coating solution obtained.

As the charge transport material in the charge transport layer, the above charge transport material can be used. As the binder resin used together with the charge transport material, various known resins can be used. Thermoplastic resins and curable resins such as polycarbonate resins, polyester resins, polyarylate resins, acrylic resins, methacrylate resins, styrene resins, and silicone resins can be used. Particularly preferred are polycarbonate resins, polyarylate resins, and polyester resins, which are less likely to cause wear and scratches. As the bisphenol component of the polycarbonate resin, bisphenol A, bisphenol C, bisphenol P, bisphenol Z, or various known components can be used. It may also be a copolymer of these components. The compounding ratio of the charge transport material and the binder resin is, for example, 10 to 200 parts by weight, preferably 30 to 150 parts by weight, based on 100 parts by weight of the binder resin. In the case of a laminated type photoreceptor, the charge transport layer is formed by using the above components as main components.

Solvents used for the charge transport layer coating liquid include tetrahydrofuran, 1,4-dioxane, 1,2.
-Ethers such as dimethoxyethane and anisole; ketones such as methyl ethyl ketone, 2,4-pentanedione and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate, methyl formate and dimethyl malonate; 3 Ether ethers such as methoxybutyl acetate and propylene glycol methyl ether acetate; and chlorinated hydrocarbons such as dichloromethane and dichloroethane. Of course, one kind or two or more kinds may be selected from these and used. Preferably, tetrahydrofuran, 1,4-dioxane, 2,4
-Pentanedione, anisole, toluene, dimethyl malonate, 3-methoxybutyl acetate, propylene glycol methyl ether acetate are preferred.

Further, the photosensitive layer may contain a well-known plasticizer, antioxidant, ultraviolet absorber and leveling agent in order to improve film-forming property, flexibility, coating property and mechanical strength. Further, on the photosensitive layer, the mechanical properties are improved and ozone, NO. An overcoat layer may be provided to improve gas resistance such as x. Needless to say, it may have an adhesive layer, an intermediate layer, a transparent insulating layer, and the like, if necessary.

In the present invention, the coating operation for forming each of the layers described above follows the conventionally known coating method. For example,
A dip coating method, a spray coating method, a spinner coating method, a blade coating method or the like can be adopted.

Examples of the image forming apparatus of the present invention include a color printer, a color copying machine, a facsimile and the like. In particular, the photoconductor of the present invention can provide a high quality image, and is therefore suitable for a high resolution image forming apparatus. In particular, it can be used for an image forming apparatus that obtains an image having a resolution of 600 dpi or more. Further, in the image forming apparatus of the present invention, the effect of the present invention can be usually obtained by using a light source such as a laser beam having a conventionally known wavelength range, but a light source having a wavelength range of 380 nm to 600 nm. It is considered that the effect of the present invention can be achieved also in the image forming apparatus utilizing the above. When performing full-color printing, the image forming apparatus temporarily transfers a developer such as toner adhered on the electrophotographic photosensitive member onto one intermediate transfer belt, and the toner of each color is transferred onto the intermediate transfer belt. Alternatively, a color visible image may be formed, and then a color image may be formed on a recording medium (paper) using a transfer unit.

[0054]

As is apparent from the above description, according to the tandem type color image forming apparatus photosensitive drum and the tandem type color image forming apparatus of the present invention, a clear image without image shift or image blur is obtained. It is extremely advantageous in the above. Further, according to the method of disposing the photoconductor drum of the present invention, it is possible to easily and surely assemble the tandem type color image forming apparatus that can obtain a clear image without image shift or image blur.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a tandem type color image forming apparatus.

FIG. 2A is a front view of a photosensitive drum, and FIG. 2B is an exploded view of the photosensitive drum.

FIG. 3 is a relationship diagram of a photosensitive drum, a driving gear, and a driven gear.

FIG. 4 is an explanatory diagram of a positional relationship between two photosensitive drums when an image shift is minimum.

FIG. 5 is an explanatory diagram of a positional relationship between two photosensitive drums when an image shift is maximum.

[Explanation of symbols]

2 Tandem type color image forming device 14 drum body 16 First flange member 18 Second flange member

Claims (14)

[Claims] 1. A plurality of photosensitive drums having the same diameter D and having photosensitive layers formed on their respective outer peripheral surfaces and rotated about a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction. In the photoconductor drums for tandem type color image forming apparatus arranged in parallel to each other, the plurality of photoconductor drums have a radial deviation of 30 μm or less with respect to each of the central axes. Furthermore, the angular difference between the shake directions of any two photoconductor drums among the plurality of photoconductor drums and the axial distance S between the two photoconductor drums are calculated as follows. The plurality of photoconductor drums are arranged so that the difference between them and the angular difference corresponding to the remainder when divided by the circumferential length πD is within a range of ± 45 degrees. Photoconductor driver for color image forming apparatus Mu. 2. A plurality of photosensitive drums having the same diameter D and having photosensitive layers formed on the respective outer peripheral surfaces thereof and rotated about a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction. In the tandem type color image forming apparatus photosensitive drums arranged in parallel with each other, the plurality of photosensitive drums have a difference in radial deviation of 30 μm or less with respect to each of the central axes. And the axial difference S between the two photoconductor drums and the axial difference S between the shake directions of any two photoconductor drums among the plurality of photoconductor drums. The plurality of photosensitive drums are arranged such that the difference between the angular difference corresponding to the remainder when divided by the peripheral length πD of the photosensitive drum falls within a range of ± 45 degrees. For tandem type color image forming device Photoconductor drum. 3. A plurality of photosensitive drums having the same diameter D and having photosensitive layers formed on respective outer peripheral surfaces thereof and rotated about a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction. In the tandem-type color image forming apparatus arranged in parallel with each other, the plurality of photoconductor drums are formed such that the magnitude of the radial deflection with respect to the central axis is 30 μm or less. Further, the angular difference between the shake directions of any two photoconductor drums among the plurality of photoconductor drums and the axial distance S between the two photoconductor drums are defined by the circumferential length πD of the photoconductor drums. A tandem-type color image forming apparatus, characterized in that the tandem-type color image forming apparatus is arranged such that a difference between the angle difference corresponding to the remainder when divided is within ± 45 degrees. 4. A plurality of photosensitive drums having the same diameter D and having photosensitive layers formed on their respective outer peripheral surfaces and rotated about a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction. In the tandem type color image forming apparatus arranged in parallel to each other, the plurality of photoconductor drums have a difference in radial deviation with respect to the central axis of each of the plurality of photoconductor drums within a range of 30 μm or less. Furthermore, the angular difference between the shake directions of any two photoconductor drums among the plurality of photoconductor drums and the axial distance S between the two photoconductor drums are calculated as follows. The tandem-type color image forming apparatus is arranged such that a difference between the angle difference corresponding to the remainder when divided by the circumference length πD falls within a range of ± 45 degrees. 5. An angular difference between the shake directions of any two photoconductor drums among the plurality of photoconductor drums, and the difference between them.
The distance S between the axes of the photoconductor drums is the peripheral length π of the photoconductor drum.
3. The plurality of photosensitive drums are arranged such that a difference between the angular difference corresponding to the remainder when divided by D is substantially zero. 5. A photosensitive drum for a tandem type color image forming apparatus or the tandem type color image forming apparatus according to claim 3. 6. The photosensitive drum is composed of a drum body and a flange member attached to an end of the drum body, and the shaft supporting portion of the photosensitive drum is a shaft supporting portion provided on the flange member. The tandem type color image forming apparatus according to claim 4 or 5, wherein the photosensitive drum for the tandem type color image forming apparatus according to claim 1 or 2. 7. The plurality of photosensitive drums is provided with a mark indicating a radial deflection direction with respect to the central axis at a location visible from the outside. The photosensitive drum for a tandem type color image forming apparatus according to claim 2 or the tandem type color image forming apparatus according to claim 3 or 4. 8. The photosensitive drum comprises a drum body and a flange member attached to an end portion of the drum body, and a fitting hole is provided at the end portion of the drum body. Is provided with a cylindrical portion fitted into the fitting hole, and the direction of deflection of the drum body with reference to the fitting hole and the direction of deflection of the cylindrical portion with reference to the shaft supporting portion of the flange member. 3. The photosensitive member for a tandem type color image forming apparatus according to claim 1 or 2, wherein the cylindrical portions are fitted in the fitting holes in substantially the same direction or substantially in the opposite direction. A body drum or a tandem type color image forming apparatus according to claim 3 or 4. 9. The photosensitive drum comprises a drum body and a flange member attached to an end portion of the drum body, and a fitting hole is provided at the end portion of the drum body. Is provided with a cylindrical portion fitted into the fitting hole, and the direction of deflection of the drum body with reference to the fitting hole and the direction of deflection of the cylindrical portion with reference to the shaft supporting portion of the flange member. And the tube portions are fitted in the fitting holes in substantially the same direction or in the substantially opposite direction, the shaft support portion of the flange member is formed of a bearing hole, and the deflection direction of the tube portion is The tandem type color image forming apparatus according to claim 3 or 4, wherein the bearing hole is used as a reference. 10. The photosensitive drum includes a drum body,
The drum body is formed of a flange member attached to an end portion of the drum body, a fitting hole is formed in the end portion of the drum body, and a cylindrical portion is formed in the flange member. The direction of the runout of the drum main body with respect to the fitting hole and the direction of the runout of the cylindrical portion with respect to the shaft support of the flange member in substantially the same direction or in opposite directions. The cylindrical portion is fitted into the fitting hole, the shaft supporting portion of the flange member is formed of a bearing hole, and the deflection direction of the cylindrical portion is determined by rotating the flange member with the bearing hole as a reference. The photosensitive drum for a tandem type color image forming apparatus according to claim 1 or 2, or the tandem type color image forming apparatus according to claim 3 or 4, which is measured. 11. The photosensitive drum includes a drum body,
The drum body is formed of a flange member attached to an end portion of the drum body, a fitting hole is formed in the end portion of the drum body, and a cylindrical portion is formed in the flange member. 3. The tandem mold according to claim 1, wherein the flange member is attached to an end portion of the drum body by fitting the tubular portion into the fitting hole by a press-fitting machine. 5. A photosensitive drum for a color image forming apparatus or the tandem type color image forming apparatus according to claim 3 or 4. 12. A tandem type color image forming apparatus, wherein a photosensitive layer is formed on each outer peripheral surface having the same diameter D and is rotated about a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction. When arranging a plurality of photosensitive drums arranged in parallel with each other, the magnitude of the radial deflection with respect to the central axis is 30 μm.
A plurality of photosensitive drums of m or less are prepared, and the plurality of photosensitive drums are provided with a mark indicating the direction of radial deflection with respect to the central axis of each of the photosensitive drums at a location visible from the outside. While visually recognizing the mark, the angular difference between the shake directions of any two photoconductor drums among the plurality of photoconductor drums and the axial distance S between the two photoconductor drums are calculated. The plurality of photoconductor drums are arranged so that the difference between the difference and the angular difference corresponding to the remainder when divided by the circumference length πD falls within the range of ± 45 degrees. A method for disposing a photosensitive drum of a tandem color image forming apparatus. 13. A tandem type color image forming apparatus, wherein a photosensitive layer is formed on each outer peripheral surface having the same diameter D and is rotated about a central axis connecting the centers of axially supporting portions at both ends in the longitudinal direction. When a plurality of photosensitive drums are arranged in parallel to each other, the difference in the magnitude of radial runout with respect to the central axis is 3
A plurality of photoconductor drums within a range of 0 μm or less is prepared, and a mark indicating the direction of radial deflection with respect to the central axis of each of the plurality of photoconductor drums is provided at a location where it can be visually recognized from the outside. By providing the mark, while visually recognizing the mark, the angular difference between the shake directions of any two photoconductor drums among the plurality of photoconductor drums and the axial distance S between the two photoconductor drums are displayed. The plurality of photoconductor drums are arranged such that the difference between the angle difference corresponding to the surplus when divided by the peripheral length πD of the photoconductor drums is within ± 45 degrees. A method for disposing a photosensitive drum of a tandem type color image forming apparatus characterized by the above. 14. The photosensitive drum includes a drum body,
14. A flange member attached to an end portion of the drum body, and a shaft supporting portion of the photosensitive drum is a shaft supporting portion provided on the flange member. A method for disposing a photosensitive drum of the tandem type color image forming apparatus described above.