JPH10254297A - Supporting mechanism for photoreceptor drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the eccentricity of a photoreceptor drum surely enough with a simple constitution. SOLUTION: This supporting mechanism rotatably supports the photoreceptor drum 2 including a drum main body 12 between a side plate rear 4 and a side plate front 8. Bearings 16 and 18 are attached to the outer peripheral surfaces of both ends of the main body 12 and bearing means 6 and 10 supporting the corresponding bearings are disposed on the plates 4 and 8. The bearing means 6 and 10 include a lower bearing member 30 having a supporting surface capable of supporting two spots putting a vertical line passing the shaft center O of the bearing in between in an area lower than a horizontal line passing the shaft center O on the outer peripheral surface of the corresponding bearing in a point contact state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive drum support mechanism used in an image forming apparatus such as an electrostatic copying machine, an electrostatic printer or an electrostatic facsimile.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrostatic copying machine, an electrostatic printer or an electrostatic facsimile, a photosensitive drum having a photosensitive member disposed on an outer peripheral surface is used.
The photoreceptor drums are rotatably supported on side walls of the image forming apparatus arranged at intervals from each other or on both side walls of an image forming unit supported by the image forming apparatus main body. The photoconductor drum is required to rotate as smoothly as possible without eccentricity (without blurring) while being supported by the side wall. In particular, in a known color image forming apparatus having four image forming units having toners of different colors from each other, the eccentricity of each photosensitive drum is a major cause of color misregistration. Requires exceptional precision. That is,
In the color image forming apparatus according to the above aspect, each of the photosensitive drums can be easily and accurately positioned at a predetermined axial center, and the horizontal parallelism can be easily and accurately secured. Is particularly required.

A typical example of a conventional photosensitive drum support mechanism is a mechanism in which a bearing is supported at both ends of a shaft provided on the photosensitive drum, and is rotatably supported on a side wall via a bearing case. (See, for example,
-67191). The photoreceptor drum includes a hollow cylindrical drum main body having a photoreceptor disposed on an outer peripheral surface thereof and flange members press-fitted into inner peripheral surfaces at both axial ends of the drum main body. The shaft extends through each of the flange members and bearings are supported at opposite ends of the shaft. The photosensitive drum is rotatably supported on the side wall by rotatably supporting each of the bearings on the corresponding side wall via a bearing case.

[0004]

In the above-described conventional photosensitive drum support mechanism, the distance between the inner peripheral surfaces of both ends of the drum body in the axial direction and the outer peripheral surfaces of the flange members is reduced.
Between each inner peripheral surface of the flange member and the outer peripheral surface of the shaft, between the outer peripheral surface of the shaft and each inner ring of the bearing, and between each outer ring of the bearing and the inner peripheral surface of the bearing case. It is a loose fit. In this way, there are many places where play is likely to occur due to the large number of clearance fits, and when the photosensitive drum is driven to rotate while being supported on the side wall, blurring, that is, eccentricity increases, There is a problem with. As a result, it can be said that it is difficult to apply the present invention to the color image forming apparatus of the above-described embodiment, in which the accuracy with respect to the eccentricity is particularly required. Further, the photosensitive drum must be supported on the corresponding side wall by an axial fitting operation, which makes the supporting operation difficult. The replacement work is also difficult due to the difficulty of the support work. Furthermore, there are also problems that the number of parts is large, the configuration is complicated, and the manufacturing cost is high.

[0005] An image forming apparatus provided with a shaft support position adjusting means capable of adjusting the position of one end of the photosensitive drum in order to prevent the eccentricity of the photosensitive drum as described above is disclosed in, for example, Japanese Patent Application Laid-Open No.
No. 43173, JP-A-4-62573, JP-A-4-62574 and the like. However, also in these apparatuses, the configuration of the photosensitive drum support mechanism itself is substantially the same as the mechanism described above, and the above problem cannot be said to have been solved yet.

[0006] Further, each of the pivot position adjusting means in the above-mentioned apparatus has a problem that the number of parts is large and the configuration as a whole is complicated. For example, JP-A-4-62
No. 573, JP-A-4-62574, one end of a photoreceptor shaft of a photoreceptor drum is supported on one side plate of an image forming apparatus, and the other end is provided on the other side plate. It is supported on the face plate via a shaft position adjusting means. The shaft support position adjusting means includes a holder fixed to the face plate, a bearing for supporting the photoreceptor shaft, a slider holding the bearing and slidable in the holder in the copy paper transport direction, and moving the slider in the copy paper transport direction. And a first elastic member for urging the slider toward the adjusting screw, and a second elastic member for pressing the bearing against a vertically extending engaging surface provided in the slider. It is configured as follows.
According to the shaft support position adjusting means, one end of the photoreceptor shaft can be adjusted in the copy paper conveying direction by using the adjusting screw. However, as described above, the number of parts is large, and the overall configuration is complicated. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a main object of the present invention is to provide a new and improved photosensitive drum which can sufficiently prevent eccentricity of the photosensitive drum with a simple structure. The purpose is to provide a support mechanism.

[0008]

According to the present invention, a photosensitive drum including a hollow cylindrical drum body having a photosensitive member disposed on an outer peripheral surface thereof is provided between a pair of opposed side walls at an interval. In a support mechanism of a photosensitive drum in an image forming apparatus for rotatably supporting, a bearing is mounted on each of outer peripheral surfaces of both ends of the drum main body, and each of the side walls supports the corresponding bearing. Bearing means are provided, each of the bearing means, when viewed in the axial direction of the photoreceptor drum, in a region on an outer peripheral surface of the corresponding bearing and below a horizontal line passing through the axial center of the bearing. A lower bearing member having a pair of support surfaces formed so as to be able to support two points sandwiching a vertical line passing through the center of the axis by point contact, respectively. It is subjected.

In the above invention, the bearings are mounted on the outer peripheral surfaces of both ends of the drum body, and each of the bearings is supported on the corresponding side wall via the bearing means. Even if the bearing means is interposed between the side wall and the side wall, the clearance fit portion is minimized as compared with the above-described conventional photosensitive drum supporting mechanism in which the shaft exists, and as a result, The locations where play is likely to occur are minimized, and shake or eccentricity during rotation of the photosensitive drum is sufficiently and reliably prevented.

[0010] Further, the outer peripheral surface of each of the bearings is configured so that two semicircular portions below a horizontal line passing through the center of the shaft are supported by the pair of supporting surfaces of the lower bearing member by point contact. The axial center of the photosensitive drum can always be positioned at the same position with respect to the lower bearing member positioned on the corresponding side wall. (Each of the lower bearing members is a single piece having a pair of support surfaces formed thereon. It is very easy to achieve accurate positioning with respect to the side walls). As a result, the photoreceptor drum support mechanism according to the present invention is suitably used in the color image forming apparatus of the above-described embodiment, in which the eccentricity precision is particularly required. That is, in the color image forming apparatus of the above-described embodiment, the parallelism in the horizontal direction of the axis of the four photosensitive drums is particularly important. Since the support can be easily and accurately supported at a predetermined position with respect to the bearing member, the parallelism of the four photosensitive drums does not change and is always kept constant.

According to the present invention, in addition to the first configuration, each of the bearing means further includes at least one portion of the outer peripheral surface of the bearing above the horizontal line. There is provided a support mechanism for a photosensitive drum including an upper bearing member having at least one pressing surface formed so as to be pressed by point contact.

[0012] According to the above invention, two portions of the outer peripheral surface of each of the bearings, the semicircular portion below the horizontal line passing through the center of the shaft, are supported by the corresponding pair of supporting surfaces of the corresponding lower bearing member by point contact. In addition, at least one portion of the semicircle above the horizontal line passing through the center of the shaft is configured to be pressed by point contact with at least one pressing surface of the corresponding upper bearing member. In other words, since the outer peripheral surface of each bearing is supported by the corresponding lower bearing member and upper bearing member by being pinched without play by at least three points by point contact, the axial center of the photosensitive drum is easily positioned at a predetermined position. The photosensitive drum is reliably positioned, and shake or eccentricity during rotation of the photosensitive drum is sufficiently prevented.

According to the above-mentioned invention, the number of parts is small as a whole, and the structure is significantly simplified, so that it can be manufactured at a relatively low cost.

According to the present invention, in addition to the first configuration, each of the bearing means further includes a point contact on the top of the outer peripheral surface of the bearing and above the horizontal line. There is provided a support mechanism for a photosensitive drum, including an upper bearing member having one pressing surface formed so as to be able to be pressed.

According to the above-mentioned invention, the outer peripheral surface of each bearing is supported by the corresponding lower bearing member and upper bearing member by being pinched without play by the point contact at the minimum number of three places, respectively. The center of the axis of the photosensitive drum is easily and reliably positioned at a predetermined position, and blurring or eccentricity during rotation of the photosensitive drum is sufficiently reliably prevented. Furthermore, since the number of parts is small as a whole and the configuration is significantly simplified, it can be manufactured at a relatively low cost.

According to the invention, in addition to the configuration described in the first aspect, each of the bearing means further includes a center of the shaft in an area of the outer peripheral surface of the bearing above the horizontal line. Provided is a support mechanism for a photosensitive drum including an upper bearing member having a pair of pressing surfaces formed so as to be able to press two points sandwiching a passing vertical line by point contact.

In the above invention, the outer peripheral surface of each bearing is formed by the corresponding lower bearing member and upper bearing member.
Since each point is supported by being pinched without play by point contact, the axial center of the photoconductor drum is easily and reliably positioned at a predetermined position and more stably. Eccentricity is sufficiently reliably prevented. Further, since the number of parts is small as a whole and the configuration is significantly simplified, it can be manufactured at a relatively low cost.

According to the present invention, in addition to the configuration described in the first aspect, in each of the lower bearing members, the corresponding bearing is supported or disengaged vertically above the pair of support surfaces. A support mechanism for the photosensitive drum is provided, in which a mounting space is formed to allow the bearing to move in the vertical direction during the operation.

In the above invention, it is not necessary to support the photosensitive drum on the corresponding side wall by the fitting operation in the axial direction, and each bearing is merely lowered from above so that each bearing can be mounted on the pair of support surfaces of the corresponding lower bearing member. Can be supported. In addition, the axial center of the photosensitive drum is accurately positioned at a predetermined position without being eccentric. As a result, the work of supporting the photosensitive drum on each of the bearing means, and hence the work of supporting each of the side walls, becomes easy. Since the supporting operation is easy, the replacement operation is also easy.

According to the present invention, in addition to the configuration described in the first aspect, a positioning hole is formed in one of the side walls, and the lower bearing member of one of the bearing means is provided with the corresponding bearing. A positioning pin portion having a common shaft center with the shaft center of the bearing is formed, and the positioning pin portion is fitted into the positioning hole to determine a mounting position of the lower bearing member with respect to the one of the side walls of the lower bearing member. A supporting mechanism for the photosensitive drum is provided.

In the above invention, even if the mounting position of each of the lower bearing members with respect to the corresponding side wall varies, the axial center of the corresponding bearing in each of the lower bearing members does not deviate and is always at a predetermined position. Is held. For example, even if one lower bearing member is attached to the positioning hole via the positioning pin portion while being slightly rotated from the regular mounting position, the positioning pin portion fits into the positioning hole at the shaft center of the bearing. It does not change with what is done. Therefore, the axial center of the photosensitive drum does not shift. Positioning when attaching each of the lower bearing members to the corresponding side wall is performed by a positioning hole formed in one of the side walls and a positioning pin portion formed in the corresponding lower bearing member, so that it is easy and accurate. Will be performed.

According to the present invention, in addition to the configuration described in the first aspect or the above-mentioned configuration, the lower bearing member on the other side of the bearing means may be disposed on the other side of the side wall with respect to the other side of the photosensitive drum. There is provided a photosensitive drum support mechanism in which the position in the horizontal direction as viewed in the axial direction is adjustable.

In the above invention, the other lower bearing member of the bearing means for supporting the other one of the bearings of the photosensitive drum can be moved in the horizontal direction directly with respect to the other one of the side walls. The horizontal position of the axis of the photosensitive drum can be adjusted while being supported by the member. Therefore, the operation of adjusting the horizontal position of the axis of the photosensitive drum can be easily performed, and the position can be accurately adjusted. In particular, when the present invention is combined with the above-described configuration, the other end of the side wall of the photosensitive drum axis is held while maintaining the axial center position of one end of the side wall of the photosensitive drum axis substantially constant. Since the axial center position of the end on the side can be adjusted in the horizontal direction, the adjustment of the horizontal position of the axis of the photosensitive drum can be easily and accurately performed. As a result, the photosensitive drum supporting mechanism according to the present invention is particularly suitably used in the color image forming apparatus of the above-described embodiment in which the parallelism of the axes of the four photosensitive drums in the horizontal direction is important. . Further, the mechanism for adjusting the position of the axis of the photosensitive drum in the horizontal direction according to the present invention has a smaller number of components and is simple in configuration than the conventional apparatus.

According to the present invention, in addition to the above configuration,
The lower bearing member includes a first guided unit and a second guided unit that is horizontally spaced from the first guided unit, and is formed to extend in the axial direction. And a positioning flange portion provided with a through hole having an axis extending in the horizontal direction is provided, and the other of the side walls has a guide surface extending in the horizontal direction. And a stationary flange portion formed to extend in the axial direction and formed with a screw hole having the axis extending in the horizontal direction, and The guide means is horizontally spaced from the second guide means, and the first guided means is movably movable in the horizontal direction on the guide surface of the first guide means. The first guided means is engaged with the second guided means, Engaged in two guide means of said guide surfaces on to be movable in the horizontal direction said second guide means,
The positioning flange portion of the lower bearing member is positioned at a distance from the other stationary flange portion of the side wall in the horizontal direction, and the positioning flange portion has the through-hole of the positioning flange portion and the stationary flange portion. The screw hole is positioned on a common horizontal axis extending in the horizontal direction, and between the positioning flange portion and the stationary flange portion, a position adjusting screw member having a head for rotating operation is provided. A spring member is disposed,
The position adjusting screw member is rotatably inserted into the through hole of the positioning flange portion so as to be relatively movable in the axial direction, and is engaged with the screw hole of the stationary flange portion. There is provided a photosensitive drum support mechanism for urging the positioning flange portion to be constantly pressed against the head of the position adjusting screw member so as to separate the positioning flange portion from the stationary flange portion in the horizontal direction.

In the above-mentioned invention, the above-described effects that the horizontal position of the axis of the photosensitive drum can be easily and accurately adjusted and that the number of parts is small and the configuration is simple as compared with the conventional apparatus are obtained. A specific configuration that can be achieved is obtained. The first guide means and the second guide means on the other side wall are horizontally spaced from each other, and the first guide means and the second guide means are provided with the first cover of the lower bearing member. Since the guide means and the first guided means are respectively movably engaged in the horizontal direction, the positioning of the lower bearing member with respect to the other side wall is easily and accurately performed, and further, the lower bearing member side wall is formed. The horizontal movement with respect to the other is stably performed.

According to the present invention, in addition to the above configuration,
The first guided means comprises a first guided portion having a common axis center with the shaft center of the bearing and having a circular outer peripheral surface, and the second guided means has a circular outer peripheral surface. A support mechanism for the photosensitive drum, wherein the first guide means and the second guide means each comprise a through hole formed in the other of the side wall. You.

In the above invention, the horizontal position of the axis of the photosensitive drum can be easily, smoothly and accurately adjusted.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a photosensitive drum supporting mechanism constructed in accordance with the present invention will be described below in detail with reference to the accompanying drawings.

Referring to FIG. 1, one end of a photosensitive drum, generally designated by reference numeral 2, is rotatably supported by one bearing means 6 mounted on rear side plate 4 constituting one of the side walls, and the other end. Is rotatably supported by the other bearing means 10 mounted on the front side plate 8 constituting the other side wall. The rear side plate 4 and the front side plate 8 are disposed so as to oppose each other at an interval to an electrostatic copying machine (not shown).

The photosensitive drum 2 is a hollow cylindrical drum body 12 which can be formed from, for example, an aluminum alloy or the like.
Flange members 14 and 15 press-fitted into inner peripheral surfaces of both ends in the axial direction of the drum main body 12, respectively;
2 are provided with ball bearings 16 and 18 which are well-known per se and are press-fitted to the outer peripheral surfaces of both ends in the axial direction. A photoreceptor is arranged on the outer peripheral surface of the drum main body 12. Each of the flange members 14 and 15 is a real shaft member integrally formed of a synthetic resin such as a POM resin. A bearing 16 having an inner ring and an outer ring is mounted on one end of the drum body 12 at the outer peripheral surface of the portion where the flange member 14 is press-fitted, by press-fitting the inner ring to the outer peripheral surface. A stop ring is mounted on the flange member 14 on the outside in the axial direction of the inner ring of the bearing 16.
This prevents the bearing 16 from moving axially outward with respect to the drum body 12. A driven gear 14a is formed integrally with the other end of the flange member 14 in the axial direction. A bearing 18 having an inner ring and an outer ring is mounted on the outer peripheral surface of the other end of the drum main body 12 at a portion where the flange member 15 is press-fitted, by press-fitting the inner ring to the outer peripheral surface. An outer diameter portion, which is larger than the inner diameter of the inner ring, is integrally provided on the flange member 15 outside the inner ring of the bearing 18 in the axial direction. This prevents the bearing 18 from moving axially outward with respect to the drum body 12.

Numeral 20 schematically indicates an imaging unit housing whose upper part is opened, and includes a side wall 22 and a side wall 2.
It has another side wall 24 spaced apart from the second side wall 24. The imaging unit housing 20 can be formed integrally from a synthetic resin such as an ABS resin. Side wall 2
2 and 24 are integrally connected by appropriate frames 25, 26, 27 and the like. The housing 20 supports, in addition to the photoreceptor drum 2, well-known devices required for image formation, such as a charging device, a developing device, a cleaning device, and a static eliminator.

One end of the photosensitive drum 2 has a bearing 1
The other end of the imaging unit housing 20 is rotatably supported on the other side wall 24 of the imaging unit housing 20 via the bearing 18. In other words, although not clearly shown in FIG. 1, the side walls 22 and 24 have a cutout extending downward from the open upper end with a width larger than the diameter of the drum body 12 and having a semicircular closed end. A notch 28 and an annular recess formed outside the closing portion and having a common axis with the closing portion, having a larger radius than the closing portion, and having a length equal to or longer than a semicircle are provided. The inner diameter of each of the closing portions is defined to be smaller than the outer diameter of the outer ring of the bearings 16 and 18. On the side walls 22 and 24, a bearing member 29 fitted in the corresponding recess and provided with a support hole for the outer ring of the corresponding bearing 16 and 18 is detachably mounted.
With both ends of the drum body 12 inserted into each of the notches 28 and positioned coaxially with the closing portion, the bearings 16 and 18 are positioned outside the closing portion, and each of the outer races is a corresponding bearing member. The photosensitive drum 2 is detachably and rotatably supported by the side walls 22 and 24 by being fitted into the support holes 29. Bearings 16 and 1
More than half of the axial width of 8 is positioned to project outwardly from sidewalls 22 and 24, respectively.

As will be described in detail later, the projecting portion of the bearing 16 of the photosensitive drum 2 is rotatably supported on the rear side plate 4 via one bearing means 6, and the projecting portion of the bearing 18 is mounted on the other bearing. It is rotatably supported by the front side plate 8 via the means 10. As a result, the imaging unit housing 2
0 is located between the side plate rear 4 and the side plate front 8. Although not shown, after the photosensitive drum 2 is supported at a predetermined position, a part of the image forming unit housing 20 is
It is fixed to a stationary member such as a not-shown frame or the like connecting the rear side plate 4, the front side plate 8, or between them by screws.

For details of the respective configurations of the above-described photosensitive drum and the mounting mechanism thereof, which have been schematically described, see Japanese Patent Application Nos. 9-24536 and 9-24537 filed by the present applicant. Are described in the specification and the drawings, and are omitted in the specification and the drawings.

One bearing means 6 includes a lower bearing member 30 and an upper bearing member 32 (see FIG. 2). 11 to 1
8, a lower bearing member 30 that can be integrally molded from a synthetic resin such as PC (polycarbonate), for example.
Is a substantially rectangular block when viewed from the front. The front end face of the block body is formed on one vertical plane, and the rear end face (rear side) is formed so as to be positioned on another vertical plane. A pair of support surfaces 34 and 36 for supporting the bearing 16 of the photosensitive drum 2 are formed on the front side of the lower bearing member 30. The support surfaces 34 and 36 are located in an area below a horizontal line passing through the reference center A of an imaginary circle C having the reference center A as an axis when viewed in the front-back direction of FIG.
Two points (2) sandwiching a vertical line passing through the reference center A in the horizontal direction
(Point) P1 and P2 are formed to make point contact with each other. In this embodiment, the support surfaces 34 and 36
Are inclined so as to approach the vertical line from above to below with the vertical line passing through the reference center A being sandwiched in the horizontal direction, and form an inclined surface coinciding with the tangent line passing through the points P1 and P2 of the virtual circle C. I have. A straight line connecting the reference center A and the points P1 and P2 forms an angle of 45 ° with a vertical line passing through the reference center A.

The imaginary circle C is defined so as to coincide with the diameter of the outer peripheral surface of the bearing 16, and the bearing 16 has an axial center O substantially common to the axial center O of the photosensitive drum 2 (see FIG. 1). . Therefore, the support surfaces 34 and 36 are, when viewed in the axial direction of the photosensitive drum 2, vertical lines passing through the shaft center O in a region below the horizontal line passing through the shaft center O of the bearing 16 on the outer peripheral surface of the bearing 16. Two places P1
And P2 can be said to be supported by point contact. In this specification, the outer peripheral surface of the bearing 16 and the axial center O of the bearing 16
A region below a horizontal line passing through the horizontal line may be simply referred to as a “lower semicircular portion”, and a region above the horizontal line may be simply referred to as an “upper semicircular portion”. The same applies to a bearing 18 described later.

On the front side of the lower bearing member 30, a pair of side walls 38 and 40 extending downward from the open upper end with a width larger than the diameter of the bearing 16 are formed. And 36 at the upper end. A pair of side walls 42 and 44 extending downward from the open upper end with a width larger than the maximum diameter of the flange member 14 including the stop ring and the driven gear 14a are formed on the back side of the side walls 38 and 40 when viewed from the front. Have been. The lower ends of the side walls 42 and 44 are substantially semicircular bottom walls 46.
It is connected to the. Side walls 38 and 40 and side walls 42 and 4
4, the bearing 16 and the flange member 1 are provided vertically above the support surfaces 34 and 36 and the bottom wall 46 when the bearing 16 is supported or separated from the support surfaces 34 and 36.
A mounting space is formed to allow the vertical movement of 4.
The side walls 42 and 44 are provided with the bearing 16 of the photosensitive drum 2.
Have a depth necessary to avoid interference with the flange member 14 including the stop ring and the driven gear 14a in a state supported by the support surfaces 34 and 36. The bottom wall 46 is formed at a position where interference with the flange member 14 can be avoided in the above-described supporting state.

The lower bearing member 30 also has three mounting holes 48 for the rear side plate 4, and two mounting holes 49 for mounting the upper bearing member 32 described later. The mounting holes 49 are formed near the upper end of the lower bearing member 30 at intervals in the horizontal direction, and each have an elongated hole extending in the vertical direction. 2 of the mounting holes 48
The plurality of pieces are formed near the lower end of the lower bearing member 30 at intervals in the horizontal direction, and one piece is formed below one of the mounting holes 49 with an interval.

On the back side of the lower bearing member 30, a positioning pin portion 50 and another pin portion 52 are formed so as to protrude from the end face on the back side. The positioning pin portion 50 is positioned so as to have a common axis center with the reference center A. The other pin portions 52 are formed horizontally spaced from the positioning pin portions 50 when viewed in the axial direction. The axis center of the other pin portion 52 is positioned on a horizontal line passing through the axis center of the positioning pin portion 50. A notch portion 54 extending from the back surface toward the front surface and having an open side is provided on the back surface side of the lower bearing member 30.
Are formed.

Referring to FIGS. 1 to 6, a positioning pin 50, another pin 52, three mounting holes 48, 2
Positioning holes 56, long holes 58, three mounting screw holes 60, two holes 62, and an intermediate gear mounting hole 64 are formed at positions respectively corresponding to the mounting holes 49 and the notch portions 54. ing. The elongated hole 58 extending in the horizontal direction is formed at a distance from the positioning hole 56 in the horizontal direction, and its center is located on a horizontal line passing through the axial center of the positioning hole 56.

The mounting position of the lower bearing member 30 with respect to the rear side plate 4 is determined by the positioning pin portion 50 of the lower bearing member 30 being removably fitted into the positioning hole 56 of the rear side plate 4. That is, the positioning pin portion 50 is
6, the positioning pin portion 50 is positioned on a common axis center with the axis center of the positioning hole 56. The other pin portion 52 of the lower bearing member 30 has a long hole 58
On the other hand, the other pin portions 52 are fitted so as to be relatively movable while the axial center thereof is held on a horizontal line. Next, the lower bearing member 30 is fixed to the rear side plate 4. This fixing is performed by engaging screws 66 with three mounting screw holes 60 of the rear side plate 4 via the three mounting holes 48 of the lower bearing member 30.

As described above, since the support surfaces 34 and 36 of the lower bearing member 30 and the vertically upper portion of the bottom wall 46 are open, the photosensitive drum can be operated simply by lowering the imaging unit housing 20. Bearing 1 at one end of 2
The outer peripheral surface of the sixth, which protrudes outward from the side wall 22, is placed and supported on the supporting surfaces 34 and 36 of the lower bearing member 30 by point contact when viewed from the axial direction, respectively. Moreover, the axial center O at one end of the photosensitive drum 2 is accurately positioned at a predetermined position. By lowering the imaging unit housing 20, the bearing 1 at the other end of the photosensitive drum 2 is moved.
8 as will be described later.
0 is similarly supported by the lower bearing member 32.

Next, the upper bearing member 32 of one bearing means 6 will be described with reference to FIGS. For example, the upper bearing member 32, which can be integrally molded from a synthetic resin such as PC (polycarbonate), forms a block having pressing surfaces 70 and 72 formed at its lower end. The front end face of the block body is formed on one vertical plane, and the rear end face (rear side) is formed so as to be positioned on another vertical plane.

The pressing surfaces 70 and 72 are
19, which is the axis direction of FIG.
A point above two points (two points) P3 and P4 of the imaginary circle C centered on the vertical line passing through the reference center A in a region above the horizontal line passing through the reference center A is sandwiched in the horizontal direction. Is formed. In this embodiment, the pressing surfaces 70 and 72 are inclined so as to be separated from the vertical as going downward from above with the vertical passing through the reference center A being sandwiched in the horizontal direction, and the points P3 and P
4 has an inclined surface coinciding with the tangent line. The straight line connecting the reference center A with the points P3 and P4 forms an angle of 45 ° with the vertical line passing through the reference center A.

The imaginary circle C is defined so as to coincide with the diameter of the outer peripheral surface of the bearing 16, and the bearing 16 has an axial center O substantially common to the axial center O of the photosensitive drum 2 (see FIG. 1). . Therefore, the pressing surfaces 70 and 72 are, when viewed in the axial direction of the photosensitive drum 2, vertical lines passing through the shaft center O in a region above the horizontal line passing through the shaft center O of the bearing 16 on the outer peripheral surface of the bearing 16. Are formed so that they can be pressed by point contact at two places,
It can be said that.

Near the upper end of the upper bearing member 32,
Two holes 74 are formed at intervals in the horizontal direction. In each of the holes 74, a metal cylindrical member 78 having a screw hole 76 formed in the inner surface is press-fitted. Screw hole 76
Is for attaching the upper bearing member 32 to the lower bearing member 30, and its position is determined so as to be aligned with the mounting hole 49 of the lower bearing member 30.

As described above, the lower semicircular portion of the outer peripheral surface of the bearing 16 at one end of the photosensitive drum 2 is placed and supported on the support surfaces 34 and 36 of the lower bearing member 30 fixed to the rear plate 4 of the side plate. After that, the upper bearing member 32 is brought into contact with the lower bearing member 30 in a state where the pressing surfaces 70 and 72 of the upper bearing member 32 are in contact with the upper semicircular portion of the outer peripheral surface of the bearing 16 and are pressed downward. Fixed. Lower bearing member 3 of upper bearing member 32
The fixing to zero is performed by aligning each of the screw holes 76 of the upper bearing member 32 with the corresponding mounting holes 49 of the lower bearing member 30 and inserting screws 79 from the mounting holes 49 to engage with the screw holes 76. Is done. As a result, four locations on the outer peripheral surface of the bearing 16 are sandwiched between the support surfaces 34 and 36 of the lower bearing member 30 and the pressing surfaces 70 and 72 of the upper bearing member 32 without play, and are firmly supported (fixed).

An intermediate gear (not shown) is attached to the hole 64 of the rear side plate 4, and the intermediate gear is located in the cutout 54 of the lower bearing member 30. The intermediate gear is drivingly connected to an electric motor (not shown) via a gear transmission mechanism (not shown). Therefore, the imaging unit housing 20
Is lowered so that the bearing 16 at one end of the photosensitive drum 2 is supported on the lower bearing member 30, and the flange portion 14 is
The driven gear 14a is meshed with the intermediate gear to form a drive system for the photosensitive drum 2.

Next, the other bearing means 10 will be described. The bearing means 10 includes a lower bearing member 80 and an upper bearing member 82.
(See FIG. 9). 23 to 29, lower bearing member 80, which can be integrally molded from a synthetic resin such as PC (polycarbonate), has a substantially L-shaped block when viewed from the front. The front end face of the block body is formed on one vertical plane, and the rear end face (rear side) is formed so as to be positioned on another vertical plane. On the front side of the lower bearing member 80,
A pair of support surfaces 84 and 86 for supporting the bearing 18 of the photosensitive drum 2 are formed. The support surfaces 84 and 86 have substantially the same configuration as the support surfaces 34 and 36 of the lower bearing member 30. That is, the support surfaces 84 and 86 are formed by a virtual circle C having the reference center A as the axis when viewed in the front-back direction of FIG.
The reference center A in an area below a horizontal line passing through the reference center A
Are formed so as to make point contact with two points (two points) P1 and P2 respectively sandwiching a vertical line passing through in the horizontal direction. In this embodiment, the support surfaces 34 and 36 are inclined so as to approach the vertical line from above to below with the vertical line passing through the reference center A interposed therebetween in the horizontal direction, and define the points P1 and P2 of the virtual circle C. It has an inclined surface that matches the tangent that passes. A straight line connecting the reference center A and the points P1 and P2 forms an angle of 45 ° with a vertical line passing through the reference center A.

The imaginary circle C is defined so as to coincide with the diameter of the outer peripheral surface of the bearing 18, and the bearing 18 has an axial center O substantially common to the axial center O of the photosensitive drum 2 (see FIG. 1). . Therefore, the support surfaces 84 and 86 are, when viewed in the axial direction of the photosensitive drum 2, a vertical line passing through the shaft center O in a region below the horizontal line passing through the shaft center O of the bearing 18 on the outer peripheral surface of the bearing 18. Two places P1
And P2 can be said to be supported by point contact.

On the front side of the lower bearing member 80, a pair of side walls 88 and 90 extending downward from the open upper end with a width larger than the diameter of the bearing 18 are formed. And 86 are connected to the upper ends. A pair of side walls 92 and 94 extending downward from the open upper end with a width larger than the maximum diameter of the flange member 15 are formed on the back side of the side walls 88 and 90 when viewed from the front. The lower ends of the side walls 92 and 94 are connected to a substantially semicircular bottom wall 96. By the side walls 88 and 90 and the side walls 92 and 94, the support surfaces 84 and 86 and the bottom wall 96 are provided.
A mounting space is formed above the vertical direction to allow the bearing 18 and the flange member 15 to move in the vertical direction when the bearing 18 is supported on or separated from the support surfaces 84 and 86. When the bearings 18 of the photosensitive drum 2 are supported by the support surfaces 84 and 86, the side walls 92 and 94
It has a depth necessary to avoid interference with the flange member 15. The bottom wall 96 holds the flange member 15
It is formed at a position where it can avoid interference.

The lower bearing member 80 is disposed so that its horizontal position can be adjusted relative to the front side plate 8 in the axial direction of the photosensitive drum 2. More specifically, the lower bearing member 80 is integrally formed with the cylindrical portion 100, the needle bearing 102 is provided, and the positioning flange portion 1 is provided.
04 are integrally formed. The cylindrical portion 100 having a circular outer peripheral surface constitutes a first guided portion constituting a first guided portion, and is positioned so as to have a common axial center with the reference center A, and the end surface on the back side. It is formed so as to protrude from. Needle bearing 10
Reference numeral 2 denotes a second guided portion constituting a second guided portion, which is a lower end portion of the lower bearing member 80 and is provided in a through hole provided near a tip of a horizontally extending portion. It is positioned so as to be press-fitted and partly project in the axial direction from the end face on the back side.

The positioning flange 104 is a cylindrical part 1
It is positioned at a horizontal distance from the outermost surface of the rear surface of the vehicle, and is formed so as to protrude from the end face on the back side. The positioning flange 104 has a through-hole 106 having the horizontal axis. The through-hole 106 is a long hole formed to extend in the axial direction.
When viewed from the axial direction, the center of the through hole 106 is the cylindrical portion 1
It is located on a horizontal line passing through the axis center A of 00.

The lower bearing member 80 also includes an upper bearing member 80.
Three metal cylindrical members 110 each having a screw hole 108 formed on the inner surface for mounting the upper bearing member 82 to be described later.
12 are formed. Each of the cylindrical members 110 is pressed into a corresponding hole formed in the lower bearing member 80. The mounting holes 112 are formed near the upper end of the lower bearing member 80 at intervals in the horizontal direction, and each have a long hole extending in the vertical direction. Two of the cylindrical members 110 are formed at intervals in the horizontal direction near the lower end of the lower bearing member 80, and one is formed at one interval below one of the mounting holes 112.

Referring to FIGS. 7 and 8, front side plate 8 includes:
The cylindrical portion 100, the positioning flange portion 104, the needle bearing 102, the three screw holes 108, and the two mounting holes 1 of the lower bearing member 80 detachably attached thereto.
12, a through hole 114, a stationary flange portion 116, another through hole 118, and three long holes 120.
And two holes 122 are formed. Through hole 114
Is formed so as to extend relatively elongated in the horizontal direction as a whole, and has a lower guide surface 124 extending linearly in the horizontal direction at one end thereof, and a space above the lower guide surface 124. An upper guide surface 126 extending parallel to the lower guide surface 124 is formed. At the other end in the horizontal direction of the through hole 114, a stationary flange portion 116 is formed so as to extend from the front side plate 8 to the front side. Of the through hole 114,
The other end where the lower guide surface 124 and the upper guide surface 126 are not formed has a vertical interval such that the positioning flange portion 104 of the lower bearing member 80 can be inserted without interference and move in the horizontal direction. Have.

The stationary flange portion 116 is formed integrally with the side plate front 8 so as to extend from the side plate front 8 to the front side. The stationary flange portion 116 has a screw hole 128 having an axis extending in the horizontal direction. Other through holes 118
Consists of a long hole extending in the horizontal direction. In the through hole 118, a lower guide surface 130 extending linearly in the horizontal direction,
An upper guide surface 132 extending parallel to the lower guide surface 130 is formed at an interval above the lower guide surface 130. The lower guide surface 124 and the upper guide surface 126 of the through hole 114 constitute first guide means, and the other through hole 11
8. The lower guide surface 130 and the upper guide surface 132 constitute second guide means.

The cylindrical portion 100 of the lower bearing member 80 engages with the through hole 114 so as to be movable in the horizontal direction between the lower guide surface 124 and the upper guide surface 126 of the through hole 114, and substantially on the lower guide surface 124. (Fitted), the needle bearing 102 of the lower bearing member 80 is
0 is engaged with the through hole 118 so as to be movable in a horizontal direction between the upper guide surface 132 and substantially on the lower guide surface 130.
Is done. Positioning flange 104 of lower bearing member 80
Are positioned so as to protrude from the through hole 114 to the front side of the front side plate 8, and the stationary flange portion 116 of the front side plate 8.
Are positioned horizontally apart from each other. In this state, the through hole 106 of the positioning flange 104 and the screw hole 128 of the stationary flange 116 are positioned on a common horizontal axis extending in the horizontal direction.

Between the positioning flange portion 104 and the stationary flange portion 116, a position adjusting screw member 136 having a rotating head 134 and a spring member 138 are provided. The position adjusting screw member 136 is rotatably inserted into the through hole 106 of the positioning flange 104 so as to be relatively movable in the axial direction, and is engaged with the screw hole 128 of the stationary flange 116. The spring member 138 urges the head portion 134 of the position adjusting screw member 136 to always press the positioning flange portion 104 horizontally away from the stationary flange portion 116. Position adjustment screw member 13
A part of the head 134 of the sixth part is also positioned inside the other end of the through hole 114. Screws 140 are inserted from each of the long holes 120 of the front side plate 8, and are engaged with the corresponding screw holes 108 of the lower bearing member 80, whereby the lower bearing member 80 is fixed to the front side plate 8.

As described above, since the upper surfaces of the support surfaces 84 and 86 and the bottom wall 86 of the lower bearing member 80 are opened vertically, the photosensitive drum can be operated simply by lowering the imaging unit housing 20. Bearing 1 at the other end of 2
8 is mounted and supported on the supporting surfaces 84 and 86 of the lower bearing member 80 by point contact on the outer peripheral surface protruding outward from the side wall 24. Moreover, the shaft center O on the other end of the photosensitive drum 2 is accurately positioned at a predetermined position.

The upper bearing member 82 of the other bearing means 10 will be described with reference to FIGS. 30 to 33 together with FIGS. For example, the upper bearing member 82, which can be integrally molded from a synthetic resin such as PC (polycarbonate), forms a block having pressing surfaces 150 and 152 formed at its lower end. The front end face of the block body is formed on one vertical plane, and the rear end face (rear side) is formed so as to be positioned on another vertical plane.

The pressing surfaces 150 and 152 are located above the horizontal line passing through the reference center A of an imaginary circle C having the reference center A as the axis, as viewed in the front-back direction of FIG. The region is formed so as to make point contact with two points (two points) P5 and P6 sandwiching a vertical line passing through the reference center A in the horizontal direction. In this embodiment, each of the pressing surfaces 150 and 152 is inclined such that the vertical line passing through the reference center A is separated from the vertical line in a horizontal direction from the upper side to the lower side, and the point P5 of the virtual circle C is inclined.
And a sloping surface coinciding with a tangent passing through P6. The straight line connecting the reference center A with the points P5 and P6 forms an angle of 45 ° with the vertical line passing through the reference center A.

The imaginary circle C is defined so as to coincide with the diameter of the outer peripheral surface of the bearing 18, and the bearing 18 has an axial center O substantially common to the axial center O of the photosensitive drum 2 (see FIG. 1). . Therefore, the pressing surfaces 150 and 152
Are bearings 16 as viewed in the axial direction of the photosensitive drum 2.
2 of a region above the horizontal line passing through the shaft center O of the bearing 16 and sandwiching a vertical line passing through the shaft center O
It can be said that each portion is formed so as to be pressed by point contact.

In the vicinity of the upper end of the upper bearing member 82,
Two holes 154 are formed at intervals in the horizontal direction. In each of the holes 154, a metal cylindrical member 158 having a screw hole 156 formed on the inner surface is press-fitted. The screw holes 156 are for attaching the upper bearing member 82 to the lower bearing member 80, and are used to attach the mounting holes 112 of the lower bearing member 80.
Its position is determined so that it can be matched with.

Referring to FIGS. 1 and 7 to 10, as described above, the lower semicircular portion of the outer peripheral surface of bearing 18 at the other end of photosensitive drum 2 corresponds to supporting surfaces 84 and 86 of lower bearing member 80. After being placed and supported on the upper surface, the pressing surface 15 of the upper bearing member 82 is
The upper bearing member 82 is fixed to the lower bearing member 80 with the 0 and 152 abutting on the upper semicircular portion of the outer peripheral surface of the bearing 18 and being pressed downward. Upper bearing member 82
For fixing to the lower bearing member 80, each of the screw holes 156 of the upper bearing member 82 is
12 and is accomplished by engaging the screw 160 with the screw hole 156. As a result, the four locations on the outer peripheral surface of the bearing 18 are sandwiched between the lower bearing member 80 and the upper bearing member 82 without play, and are firmly supported (fixed).

As described above, when the head 134 of the position adjusting screw member 136 is rotated while one end of the photosensitive drum 2 is supported by the bearing means 6 and the other end is supported by the bearing means 10, Depending on the rotation direction, the positioning flange portion 104 of the lower bearing member 80 approaches the stationary flange portion 116 of the front side plate 8 against the biasing force of the spring member 138, or the stationary flange portion is biased by the biasing force of the spring member 138. It is moved away from the part 116. Thereby, the cylindrical portion 100 of the lower bearing member 80 is moved in the horizontal direction along the lower guide surface 124 and the upper guide surface 126 of the through hole 114 in the front side plate 8, and the needle bearing 102 of the lower bearing member 80 is Lower guide surface 1 of through hole 118
30 and along the upper guide surface 132 in the horizontal direction.

The axial center O of the cylindrical portion 100 of the lower bearing member 80
The height of the bearing 18 is kept constant by the lower guide surface 124 and the upper guide surface 126 of the through hole 114 in the side plate front 8, so that the horizontal movement of the lower bearing member 80 causes the bearing 18 of the photosensitive drum 2 to move. Of the shaft center O of the photosensitive drum 2, that is, the shaft center O at the other end of the photosensitive drum 2, the horizontal position thereof is easily and accurately adjusted while the vertical position thereof is kept constant. At one end of the photosensitive drum 2, the positioning pin portion 50 of the lower bearing member 30 is fitted into the positioning hole 56 of the rear side plate 4, so that the position adjusting screw member 13 is provided.
By the above rotation operation of 6, the axis of the photosensitive drum 2 is moved (turned) in the horizontal direction on the other end side around the positioning hole 56 on one end side. The amount of movement is small, and is therefore easily absorbed by elastic deformation, gaps and the like of each part. The axial center O of the bearing 16 at one end of the photosensitive drum 2 and thus the axial center O of one end of the photosensitive drum 2 held at a predetermined position does not change.

In the horizontal position adjustment of the other end side of the photosensitive drum 2 described above, each of the screws 140 for fixing the lower bearing member 80 to the front side plate 8 is provided with the corresponding screw hole 108 of the lower bearing member 80. Must be temporarily tightened. Thus, the above movement of the lower bearing member 80 with respect to the front side plate 8 is allowed. Since the corresponding slot 120 of the side plate front 8 into which each of the screws 140 is inserted is a slot extending in the horizontal direction, the corresponding slot 12 of each of the screws 140 is
The movement in the horizontal direction with respect to 0 is allowed, and the above adjustment is performed without any trouble.

FIG. 34 shows an upper bearing member 170 different from the upper bearing members 32 and 82. FIG.
4 shows a state in which the upper bearing member 170 is mounted on the lower bearing member 30 on one end side of the photosensitive drum 2, and is a view corresponding to FIG. 2 except for the upper bearing member 170. Therefore, the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.
For example, the upper bearing member 170, which can be integrally formed of a synthetic resin such as PC (polycarbonate), has an outer peripheral surface of the bearing 16 and a top portion of a region above the horizontal line as viewed in the axial direction of the photosensitive drum 2. Point contact (point P
One holding surface 1 formed so as to be held by 7)
72. The pressing surface 172 extends horizontally when viewed from the front, and is formed to coincide with one tangent passing through the outer peripheral surface of the bearing 16. Near the upper end of the upper bearing member 170, two holes are formed at intervals in the horizontal direction. In each of the holes, a metal cylindrical member 174 having a screw hole formed in the inner surface is press-fitted. Each of the screw holes is for mounting the upper bearing member 170 to the lower bearing member 30, and is positioned so as to be aligned with the corresponding mounting hole 49 of the lower bearing member 30.

The lower semicircular portion of the outer peripheral surface of the bearing 16 at one end of the photosensitive drum 2 corresponds to the support surfaces 34 and 3 of the lower bearing member 30.
After being placed and supported on the upper bearing member 6, the pressing surface 172 of the upper bearing member 170 is brought into contact with the vertex P7 of the outer peripheral surface of the bearing 16 and pressed downward, and
70 is fixed to the lower bearing member 30. Upper bearing member 170
The fixing to the lower bearing member 30 is performed by the screw 176 in the same manner as described above. Thereby, three places on the outer peripheral surface of the bearing 16 are sandwiched between the lower bearing member 30 and the upper bearing member 170 without play, and are firmly supported (fixed).

As is clear from the description of the other embodiments of the upper bearing member, each of the bearing means in the present invention is an outer peripheral surface of the corresponding bearing when viewed in the axial direction of the photosensitive drum, and An upper bearing member having at least one pressing surface formed so as to press at least one point in a region above a horizontal line passing through the axis center by point contact.

The preferred embodiment of the photosensitive drum supporting mechanism constructed according to the present invention has been described above with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiment, and the scope of the present invention is not limited thereto. It should be understood that various changes and modifications can be made without departing from the scope of the present invention. For example, in the above embodiment, the photosensitive drum 2
Is supported between the side plate rear 4 and the side plate front 8 of the electrostatic copying machine as an image forming apparatus while being supported between the side wall 22 of the imaging unit housing and the other side wall. It goes without saying that in some embodiments, the device is directly supported between the side walls of the apparatus (between the side plate and the front of the side plate). Further, the support surfaces 34 and 3 on the lower bearing members 30 and 80, respectively.
6. The supporting surfaces 84 and 86, the pressing surfaces 70 and 72 in each of the upper bearing members 32 and 82, and the pressing surfaces 150 and 152 are all formed from inclined surfaces that coincide with tangents to the outer peripheral surfaces of the corresponding bearings 16 and 18. Has been
In place of each inclined surface, an arc surface that makes point contact with the outer peripheral surface is also established.

[0072]

According to the photosensitive drum supporting mechanism of the present invention, the eccentricity of the photosensitive drum can be sufficiently and reliably prevented by a simple structure. Therefore, the photosensitive drum support mechanism of the present invention is also suitably used for the color image forming apparatus of the above-described embodiment, in which the precision with respect to eccentricity is particularly required.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a preferred embodiment of a photoconductor drum support mechanism configured according to the present invention, and is a horizontal cross-sectional view along the axis of the photoconductor drum.

FIG. 2 is a view of one of bearing means included in the support mechanism of FIG. 1 as viewed from the front after a side plate.

FIG. 3 is a sectional view taken along the line AA of FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is a sectional view taken along the line CC of FIG. 2;

FIG. 6 is a view of FIG. 2 as viewed from the back side of the paper (a view of one of the bearing means as viewed from behind the side plate) and omitting an upper bearing member.

7 is a view of the other of the bearing means included in the support mechanism of FIG. 1 as viewed from the front in front of the side plate, with the upper bearing member omitted.

8 is a sectional view taken along the line DD in FIG. 7;

FIG. 9 is a view of FIG. 7 as viewed from the back side of the drawing (a view of the other of the bearing means as viewed from behind the side plate), with the upper bearing member attached.

FIG. 10 is a sectional view taken along the line EE in FIG. 9;

FIG. 11 is a front view of a lower bearing member included in one of the bearing means.

FIG. 12 is a top view of FIG. 11;

FIG. 13 is a left side view of FIG. 11;

FIG. 14 is a rear view of FIG. 11;

FIG. 15 is a sectional view taken along the line FF in FIG. 11;

FIG. 16 is a sectional view taken along line GG of FIG. 11;

FIG. 17 is a sectional view taken along the line HH in FIG. 11;

FIG. 18 is a sectional view taken along the line II of FIG. 11;

FIG. 19 is a front view of an upper bearing member included in one of the bearing means.

FIG. 20 is a right side view of FIG. 19;

FIG. 21 is a sectional view taken along the line JJ of FIG. 19;

FIG. 22 is a sectional view taken along the line KK of FIG. 19;

FIG. 23 is a front view of a lower bearing member included in the other of the bearing means.

FIG. 24 is a left side view of FIG. 23.

FIG. 25 is a rear view of FIG. 23;

FIG. 26 is a top view of FIG. 25.

FIG. 27 is a sectional view taken along line LL of FIG. 25;

FIG. 28 is a sectional view taken along the line MM in FIG. 25;

FIG. 29 is a sectional view taken along the line NN of FIG. 25;

FIG. 30 is a front view of an upper bearing member included in the other of the bearing means.

FIG. 31 is a left side view of FIG. 30.

FIG. 32 is a sectional view taken along the line OO in FIG. 30;

FIG. 33 is a cross-sectional view taken along the line PP of FIG. 30;

FIG. 34 is a view showing another embodiment of the bearing means shown in FIG. 2, and is a view similar to FIG. 2;

[Explanation of symbols]

 2 Photoreceptor drum 4 Rear side plate 6 One bearing means 8 Front side plate 10 The other bearing means 12 Drum main body 16, 18 Bearing 20 Imaging unit housing 30 Lower bearing member 32 Upper bearing member 34, 36 Support surface 50 Positioning pin portion 56 Positioning holes 70, 72 Holding surface 80 Lower bearing member 82 Upper bearing member 84, 86 Support surface 100 Cylindrical portion 102 Needle bearing 104 Positioning flange portion 114 Through hole 116 Stationary flange portion 118 Through hole 124, 126, 130, 132 Guide surface 136 Position adjusting screw member 150, 152, 172 Holding surface 170 Upper bearing member

Claims (9)

[Claims] 1. An image forming apparatus for rotatably supporting a photosensitive drum including a hollow cylindrical drum body having a photosensitive member disposed on an outer peripheral surface thereof between a pair of opposed side walls at an interval. In the support mechanism of the photosensitive drum in the apparatus, bearings are respectively mounted on outer peripheral surfaces of both ends of the drum main body, and bearing means for supporting the corresponding bearings are provided on each of the side walls, and the bearing means is provided. Each sandwich a vertical line passing through the center of the shaft in a region below the horizontal line passing through the center of the bearing on the outer peripheral surface of the corresponding bearing as viewed in the axial direction of the photosensitive drum. A support mechanism for a photosensitive drum, comprising: a lower bearing member having a pair of support surfaces formed so as to be able to support two places by point contact. 2. Each of the bearing means has at least one pressing surface formed so as to press at least one portion of the outer peripheral surface of the bearing above the horizontal line by point contact. The support mechanism for a photosensitive drum according to claim 1, further comprising an upper bearing member. 3. Each of the bearing means includes an upper bearing member having one pressing surface formed so as to press, by point contact, a top portion of the outer peripheral surface of the bearing above the horizontal line. The support mechanism for a photosensitive drum according to claim 1, wherein 4. Each of the bearing means is formed so as to be capable of holding two points on the outer peripheral surface of the bearing above the horizontal line and sandwiching a vertical line passing through the axis center by point contact. The support mechanism for a photosensitive drum according to claim 1, further comprising an upper bearing member having a pair of pressing surfaces provided. 5. In each of the lower bearing members, a mounting space is formed above the pair of support surfaces in a vertical direction to allow vertical movement of the bearing when supporting or detaching the corresponding bearing. The support mechanism for a photosensitive drum according to claim 1, wherein: 6. A positioning hole is formed in one of the side walls, and a positioning pin portion having a common axis center with the corresponding shaft center of the corresponding bearing is formed in one of the lower bearing members of the bearing means. 2. The photoconductor drum supporting mechanism according to claim 1, wherein said positioning pin portion is fitted into said positioning hole to determine a mounting position of said lower bearing member to said one of said side walls. 7. The lower bearing member on the other side of the bearing means is arranged such that the horizontal position of the photosensitive drum in the axial direction can be adjusted with respect to the other side wall. A support mechanism for a photosensitive drum according to claim 1. 8. The lower bearing member includes a first guided means and a second guided means which is horizontally spaced from the first guided means; A positioning flange portion formed to extend and having a through hole having an axis extending in the horizontal direction, and a guide extending in the horizontal direction is provided on the other of the side walls. A first guide means and a second guide means having surfaces, and a stationary flange portion formed to extend in the axial direction and formed with a screw hole having the axis extending in the horizontal direction are provided. Wherein the second guide means is horizontally spaced from the second guide means, and wherein the first guided means is disposed on the guide surface of the first guide means in the horizontal direction. The second guide member is movably engaged with the first guide means. The guide means is movably engaged with the second guide means on the guide surface of the second guide means in the horizontal direction, and the positioning flange portion of the lower bearing member is provided on the other side of the side wall. The through-holes of the positioning flange and the screw holes of the stationary flange are positioned on the common horizontal axis extending in the horizontal direction. A position adjusting screw member and a spring member having a head for rotating operation are disposed between the positioning flange portion and the stationary flange portion, and the position adjusting screw member is The spring member is rotatably inserted into the through hole of the flange portion and relatively movably in the axial direction, and is engaged with the screw hole of the stationary flange portion. Part in the horizontal direction Biases to press constantly head portion of Suyo the position adjusting screw member, the support mechanism of the photosensitive drum according to claim 7 wherein. 9. The first guided means comprises a first guided portion having a common axis center with the shaft center of the bearing and having a circular outer peripheral surface. 9. The device according to claim 8, wherein the first guide means and the second guide means comprise through holes formed in the other of the side walls, respectively. Support mechanism for the photosensitive drum.