JP3268519B2 - Photoreceptor drum mounting mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive drum mounting 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 photoconductor 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 mounted on the image forming apparatus main body. The photoreceptor drum is required to rotate as smoothly as possible without eccentricity (without blurring) when mounted on 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.

On the other hand, the photosensitive drum is easily and reliably detachably mounted on the side wall for cleaning when the photosensitive member is contaminated or for replacing the photosensitive drum when the photosensitive member is deteriorated. What you can do is important.

[0004] A typical example of a conventional photosensitive drum mounting mechanism is a mechanism in which bearings are mounted on both ends of a shaft provided on the photosensitive drum and 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 mounted at both ends of the shaft. The photosensitive drum is rotatably supported on the side wall by rotatably mounting each of the bearings on the corresponding side wall via a bearing case.

[0005]

Thus, in the above-described conventional photosensitive drum mounting mechanism, the distance between the inner peripheral surfaces of both ends in the axial direction of the drum main body and the outer peripheral surfaces of the respective 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 loose fit parts, and when the photoconductor drum is driven to rotate while being mounted on the side wall, blurring or 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. Also, the photoconductor drum must be mounted on the corresponding side wall by a fitting operation in the axial direction, and the mounting operation is difficult. Furthermore, there is a problem that the number of parts is large and the configuration is complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its main object to prevent eccentricity of the photosensitive drum and to easily and surely mount the photosensitive drum on the side wall. It is another object of the present invention to provide a new and improved photosensitive drum mounting mechanism.

[0007]

According to the present invention, a hollow cylindrical drum body having a photoreceptor disposed on an outer peripheral surface thereof and press-fitted into inner peripheral surfaces at both axial ends of the drum main body. A photosensitive drum mounting mechanism in the image forming apparatus for rotatably mounting a photosensitive drum including a flange member between a pair of opposed side walls at an interval,
A bearing having an inner ring and an outer ring is mounted on an outer peripheral surface of a portion where the flange member is press-fitted at the both ends of the drum main body by press-fitting the inner ring to the outer peripheral surface, and the flange member is provided. Each of the corresponding inner races is provided on its axially outer side with a large-diameter portion larger than the inner diameter of the inner race, and each of the side walls extends downward from the open upper end by a width larger than the diameter of the drum body. A notch having a semicircular closure at the lower end, formed outside each of the closures, having a common axis with each of the closures, having a larger radius than each of the closures, and An annular recess having a length of at least a semicircle, wherein the inner diameter of each of the closures is defined to be smaller than the outer diameter of the outer race of each of the bearings, and each of the side walls fits in each of the recesses. For matching and corresponding outer ring of the bearing A bearing member having a support hole is detachably mounted, and both ends of the drum main body are inserted into each of the notches and are positioned on the same axis as the closing portion. Each of the outer rings is positioned outside the closing portion and is fitted into the corresponding support hole of the corresponding bearing member, so that the photosensitive drum is detachably and rotatably supported on each of the side walls. And a mounting mechanism for the photosensitive drum.

In the above invention, the bearings are mounted directly on both ends of the drum body, and each of the bearings is mounted on the corresponding side wall via the bearing member. Even if a bearing member is interposed between the parts, the clearance fit portion is minimized as compared with the above-described conventional photosensitive drum mounting mechanism, and the portion where play is likely to occur due to this is reduced. Is minimized, and blurring during rotation of the photosensitive drum, that is, eccentricity is reliably prevented. As a result, the photoreceptor drum mounting mechanism according to the present invention is suitably used in the color image forming apparatus of the above-described embodiment, in which the accuracy with respect to eccentricity is particularly required.

Further, since the number of parts is small as a whole and the structure is significantly simplified, it can be manufactured at a relatively low cost.

In the above invention, the photosensitive drum is positioned at the mounting position from above through the notch formed in each of the side walls, and then each of the bearing members is provided with a corresponding supporting hole of the corresponding bearing. The photosensitive drum can be rotatably supported on each of the side walls by being fitted into the corresponding recess of the side wall while being fitted to the outer ring. Therefore, the photosensitive drum can be easily and reliably mounted on the side wall. Further, since the photosensitive drum can be easily and accurately mounted at a predetermined position with respect to the side wall, the eccentricity of the photosensitive drum can be reliably prevented.

In the above invention, a large-diameter portion larger than the inner diameter of the inner ring is provided on the outer side in the axial direction of each corresponding inner ring of the flange member. Since each bearing is defined to be smaller than the outer diameter of its corresponding outer race, the axial inward movement (falling out) of each of the bearings is reliably prevented by the corresponding closure and the axial outer side. Movement (disengagement) is reliably prevented by the corresponding large diameter portion. Therefore, each of the bearings is prevented from moving in both axial directions with respect to each of the side walls, and is firmly mounted.

According to the present invention, the annular concave portion further comprises
A mounting mechanism for a photoconductor drum having a length equal to or longer than a semicircle, having a width smaller than its own diameter, and having an upper end defined with a width larger than the width of the notch is provided.

In the above invention, the bearing members fitted in the respective recesses are reliably prevented from moving in all directions including upward movement, and thus the photosensitive drum is moved to a predetermined position with respect to the side wall. And the eccentricity can be prevented.

According to the present invention, there is further provided a photosensitive drum mounting mechanism in which at least one of the large diameter portions provided on each of the flange members is formed integrally with the flange member.

In the above invention, since the large diameter portion for preventing the corresponding bearing from moving outward in the axial direction is formed integrally with the flange member, it is not necessary to use a separate member, and the movement preventing function is provided. It is possible to improve the cost and reduce the cost.

[0016]

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

First, the photosensitive drum 2 will be described with reference to FIG. The photosensitive drum 2 has a hollow cylindrical drum body 4 that can be formed from, for example, an aluminum alloy or the like.
And flange members 6 and 8 respectively press-fitted into the inner peripheral surfaces of both ends in the axial direction of the drum main body 4, and well-known ball bearings each press-fitted into the outer peripheral surfaces of both end portions in the axial direction of the drum main body 4 10 and 12 are provided. Although the photosensitive member is provided on the outer peripheral surface of the drum main body 4, in this embodiment, regions where the photosensitive member is not provided are provided on the outer peripheral surfaces of both end portions of the drum main body 4 (see FIG. 1). Not shown). The flange member 6 is formed of a real shaft member integrally formed of, for example, a synthetic resin such as a POM resin, and has a press-fit portion 6a having a circular outer peripheral surface, an inclined surface 6b formed at one end in the axial direction, and a shaft. And a large-diameter portion 6c formed at the other end in the direction. The diameter of the large diameter portion 6c is formed larger than the diameter of the press-fit portion 6a. The flange member 6 is mounted on one end of the drum body 4 by press-fitting the press-fitting portion 6 a of the flange member 6 into the inner peripheral surface of one end of the drum body 4.

A flange member 6 at one end of the drum body 4
The bearing 10 is mounted on the outer peripheral surface of the part where the is press-fitted. The bearing 10 has an inner ring 10a and an outer ring 10b.
It has. The inner ring 10a of the bearing 10 is press-fitted into an area on the outer peripheral surface of the drum main body 4 where the above-described photoconductor is not provided.
It is attached to. The large diameter portion 6c of the flange member 6 is positioned substantially in contact with the outside of the inner ring 10a of the bearing 10 (the outside in the axial direction of one end of the drum body 4), and has a diameter larger than the inner diameter of the inner ring 10a. ing. This prevents the bearing 10 from moving axially outward (to the right in FIG. 3) with respect to the drum body 4.

The flange member 8 is a real shaft member integrally formed of a synthetic resin such as POM resin, and has a press-fit portion 8a having a circular outer peripheral surface, and an inclined surface 8b formed at one end in the axial direction. , A driven gear 8c formed at the other end in the axial direction
And an annular groove 8d formed between the press-fit portion 8a and the driven gear 8c. Press-fit portion 8 of flange member 8
The flange member 8 is attached to the other end of the drum body 4 by pressing the a into the inner peripheral surface of the other end of the drum body 4. The flange members 6 and 8 can also be formed by cutting a sintered metal member.

The flange member 8 at the other end of the drum body 4
The bearing 12 is mounted on the outer peripheral surface of the portion where the is press-fitted. Bearing 12 includes inner ring 12a and outer ring 12b
It has. The bearing 12 is mounted on the drum body 4 by press-fitting the inner ring 12a into the outer peripheral surface of the flange member 8 where the photosensitive member is not provided. The groove 8d of the flange member 8 is positioned substantially in contact with the outside of the inner ring 12a of the bearing 12 (the outside of the other end of the drum body 4 in the axial direction),
A stop ring 14 is detachably mounted in the groove 8d. This prevents the bearing 12 from moving axially outward (to the left in FIG. 3) with respect to the drum body 4. The stop ring 14 forms a large diameter portion of the flange member 8. An embodiment in which a large-diameter portion similar to the large-diameter portion 6c of the flange member 6 is integrally formed instead of the groove 8d and the stop ring 14 of the flange member 8 is also conceivable.

The axially press-fit width of the flange member 6 with respect to the inner peripheral surface of the drum body 4 (the axial length of the press-fit portion 6a) is 6L, and the bearing 1 press-fitted to the outer peripheral surface of the drum body 4 is provided.
When the axial length of the inner ring 10a is 10 L, 6 L
≧ 10L. In the illustrated embodiment, 6L = 10L. The bearing 10
The axial lengths of the inner ring 10a and the outer ring 10b are defined equally.

Similarly, the drum body 4 of the flange member 8
When the axial press-fit width (the axial length of the press-fitting portion 8a) with respect to the inner peripheral surface of the drum 12 is 8L, and the axial length of the inner ring 12a of the bearing 12 press-fitted on the outer peripheral surface of the drum body 4 is 8L. ≧ 12L. In the illustrated embodiment, 8L = 12L. Note that the axial lengths of the inner ring 12a and the outer ring 12b of the bearing 12 are both specified to be equal.

Referring to FIGS. 4 to 6, reference numeral 20 denotes a part of the imaging unit housing whose upper part is open, and a side wall 22 and another side wall arranged at a distance from the side wall 22. (Not shown). The imaging unit housing 20 can be formed integrally from a synthetic resin such as an ABS resin. The side wall 22 and other side walls are integrally connected by appropriate frames 22a, 22b, 22c and the like. In addition to the photosensitive drum 2 according to the present invention, well-known devices required for image formation, such as a charging device, a developing device, a cleaning device, and a static eliminator, are mounted on the housing 20. Except for the side wall 22 and other side wall structures according to the present invention, other structures of the housing 20 itself do not form new features of the present invention, and a description thereof will be omitted. The housing 20 is detachably attached to a main body of the image forming apparatus (not shown).

In the side wall 22 and the other side walls, the configuration of the portion according to the present invention is substantially the same. Therefore, only the side wall 22 will be described here, and the description of the other side walls will be omitted except for necessary parts. A notch 24 is formed in the side wall 22 extending substantially vertically. Notch 24
Is formed so as to extend vertically downward and parallel from the opened upper end with a width larger than the diameter of the drum main body 4 and have a lower end forming a semicircular closing portion 24a. The inner diameter of the closing portion 24a is defined to be smaller than the outer diameter of the outer ring 10b of the bearing 10. Outside the closing portion 24a, annular concave portions (recesses formed to be lower inward than the outer surface of the side wall 22) 26 and 28 are formed. Annular recess 2
6 has a common axis with the closing portion 24a and
a having a radius larger than a and having a size of not less than a semicircle, and having upper ends 26a and 26b defined with a width smaller than the diameter of the recess 26 itself and larger than the width of the notch 24. Is formed.

The recess 26 continues to another recess 27 which extends substantially symmetrically upward along both sides of the notch 24. The other recess 27 having the same depth from the outer surface of the side wall 22 as the recess 26 is separated from the recess extending upward along both sides of the notch 24 from the upper end of the recess 26 with the notch 24 interposed therebetween. It consists of a concave portion that protrudes in the lateral direction. Screw holes 29 for mounting a bearing member 30 to be described later are respectively provided in the recesses extending in the lateral direction. Each of the screw holes 29 can be easily arranged by press-fitting a metal ring member having a screw hole into a corresponding mounting hole. The annular concave portion 28 is formed to have a common axis with the closing portion 24a and to have a radius larger than the closing portion 24a and smaller than the annular concave portion 26. The radius of the annular recess 28 is formed larger than the outer diameter of the inner ring 10 a of the bearing 10.
The upper end of the annular recess 28 is defined by a portion extending in parallel vertically below the notch 24. The concave portion 28 is formed to prevent the bearing 10 from abutting against the side surface of the inner ring 10a when the photosensitive drum 4 is mounted on the side wall 22 as described later. Each recess 26
And 28 each have a vertical flat surface.

Referring to FIGS. 7 to 9, a bearing member 30 is detachably mounted in the concave portion 26 of the side wall 22. The bearing member 30 made of a substantially plate-shaped member as a whole is, for example, P
C is formed integrally from a synthetic resin such as C resin.
It has a shape that can be fitted to. That is, the bearing member 30
Are an annular portion 32 slightly larger than a semicircle and an annular portion 32
And the mounting portion 34 above the mounting portion. A support hole 36 which is a through hole is formed in the annular portion 32. Support hole 36
Has a diameter capable of being pressed into the outer ring 10b of the bearing 10. The mounting portion 34 includes an annular portion 32 and a support hole 36.
A portion extending upward from the upper end portion of the first portion, and a portion extending in a lateral direction apart from the upwardly extending portion. A thick portion having a width smaller than that of the notch 24 is formed in a portion extending above the mounting portion 34.
The annular portion 32 is aligned with the annular concave portion 26, and the mounting portion 3
4 is formed so as to be aligned with the other concave portion 27 of the side wall 22. A mounting hole 38 is formed in each of the portions that protrude in the lateral direction. These holes 38 are in the side wall 2
The two screw holes 29 are aligned with each other.

Next, the mounting of one end of the photosensitive drum 2 to the side wall 22 will be described with reference to FIGS. The drum main body 4 of the photoconductor drum 2 is inserted into the notch 24 of the side wall 22 from above, and positioned on the same axis as the closing portion 24a. In this state, the bearing 10 is
a. Next, the bearing member 30
The bearing member 30 is positioned so as to fit into the annular concave portion 26 and the other concave portion 27 of the side wall 22 while press-fitting the support hole 36 into the outer ring 10 b of the bearing 10, and the bearing member 30 is mounted on the side wall 22 with the screw 40. . It is preferable that the outer diameter portion of the annular portion 32 of the bearing member 30 has a shape that is in close contact with the inner diameter portion of the annular concave portion 26. With this configuration, the mounting position of the bearing 10 with respect to the side wall 22 is accurately defined, and therefore, the axis of the photosensitive drum 4 is accurately positioned at a predetermined position. Further, the omnidirectional movement of the bearing 10 with respect to the side wall 22 is also firmly prevented. The inner ring 10a of the bearing 10 is prevented from moving outward in the axial direction by the large diameter portion 6c of the flange member 6, and the outer ring 10b is prevented from moving inward in the axial direction by the bottom surface of the concave portion 26 of the side wall 22. With the above configuration, the eccentricity of the photosensitive drum 4 is reliably prevented. The mounting of the other end of the photosensitive drum 2 to another side wall is performed in the same manner. In this manner, the photosensitive drum 2 is detachably and rotatably supported by the side wall 22 and other side walls.

In the embodiment described above, the axial press-fit widths 6L and 8L of the flange members 6 and 8 with respect to the inner peripheral surface of the drum main body 4 are determined by the inner rings 10a and the bearings 10 and 12 press-fitted into the drum main body 4. Since the length of the inner ring 12a is defined to be equal to or greater than 10L and 12L, the outer circumferential surface of the drum body 4 can be equally received over the entire inner circumferential surface of the inner races 10a and 12a of the bearings 10 and 12, so Is achieved. As a result, bearing 1
The axes of 0 and 12 and the axis of the drum main body 4 can be surely made coincident with each other, and the eccentricity of the drum main body 4 and therefore the photosensitive drum 2 can be reliably prevented. This allows
The mounting mechanism of the photosensitive drum according to the present invention is also suitably used for the color image forming apparatus of the above-described embodiment, which requires particularly strict eccentricity accuracy.

In the above-described embodiment, a region where the photosensitive member is not provided (painted) is provided on the outer peripheral surfaces of both ends of the drum main body 4, and the bearing 1 is provided in the unpainted region.
Since the 0 and 12 inner rings 10a and 12a are press-fitted, the inner rings 10a and 12a are prevented from being spread by the layer of the photoconductor. As a result, the eccentricity of the drum body 4 and therefore of the photosensitive drum 2 can be reliably prevented, and the smooth rotation of the bearings 10 and 12 is reliably ensured.

The preferred embodiment of the photosensitive drum mounting 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 such an 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 wall 22 of the imaging unit housing and the other side wall. However, it is needless to say that there is an embodiment in which it is supported between the side walls of the image forming apparatus main body. In the preferred embodiment, the annular concave portion 26 is formed to have a size of a semicircle or more, and the annular portion 32 of the bearing member 30 is formed.
Is configured to prevent upward movement of the bearing member 30. Alternatively, another configuration in which the upward movement of the bearing member 30 is prevented by another concave portion 27 is also possible. Also, the bearing member 3 is made of only screws.
There may be a configuration in which movement in all directions including zero is prevented. The annular concave portion 26 may have a shape having at least a semicircular length.

[0031]

According to the photosensitive drum mounting mechanism of the present invention, the eccentricity of the photosensitive drum can be reliably prevented, and the mounting on the side wall can be performed easily and reliably. Therefore, the photosensitive drum mounting mechanism of the present invention is also suitably used in the color image forming apparatus of the above-described embodiment, which requires particularly strict eccentricity accuracy.

[Brief description of the drawings]

FIG. 1 is a side view showing a preferred embodiment of a photosensitive drum mounting mechanism configured according to the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 3 is a schematic plan view showing a part of a photosensitive drum included in the present invention in a cutaway manner.

FIG. 4 is a schematic side view of an image forming unit housing on which the photosensitive drum is supported.

FIG. 5 is a schematic plan view showing a part of FIG. 4;

FIG. 6 is a sectional view taken along the line BB of FIG. 4;

FIG. 7 is a front view of a bearing member included in the present invention.

FIG. 8 is a plan view of FIG. 7;

FIG. 9 is a sectional view taken along the line CC of FIG. 7;

[Explanation of symbols]

 2 Photoreceptor drum 4 Drum main body 6, 8 Flange member 6c Large diameter portion 6L, 8L Press-fit width 10, 12 Bearing 10a, 12a Inner ring 10b, 12b Outer ring 22 Side wall 24 Notch 24a Closed portion 26 Annular concave portion 30 Bearing member 36 Support Hole

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 21/00 350 G03G 21/16-21/18 G03G 15/00 550

Claims (3)

(57) [Claims] A photosensitive drum including 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, respectively. A photosensitive drum mounting mechanism in the image forming apparatus for rotatably mounting the drum member between a pair of opposed side walls, wherein an outer peripheral surface of a portion of the drum body where the flange member is press-fitted at both ends of the drum body , A bearing having an inner ring and an outer ring is mounted by press-fitting the inner ring to the outer peripheral surface, and each of the flange members has a large inner diameter, which is larger than the inner diameter of the inner ring, on the axially outer side of the corresponding inner ring. A diameter portion is provided, each of the side walls extends downward from the open upper end with a width larger than the diameter of the drum body, and a lower end forms a semicircular closed portion; Formed outside and closed An annular recess having a common axis with each of the portions and having a larger radius than each of the closures and having a length of at least a semicircle, wherein the inner diameter of each of the closures is A bearing member, which is defined to be smaller than the outer diameter of each of the outer races, is removably mounted on each of the side walls, the bearing member having a support hole for the outer race of the corresponding bearing and being fitted into each of the recesses, With both ends of the drum body inserted into each of the notches and positioned coaxially with the closure, each of the bearings is positioned outside the closure and each of the outer races is The photosensitive drum is detachably and rotatably supported on each of the side walls by being fitted into the support hole of the bearing member. 2. The annular recess has a length that is greater than or equal to a semicircle, has a width less than its own diameter, and has an upper end defined with a width greater than the width of the notch. Item 2. A mounting mechanism for a photosensitive drum according to Item 1. 3. The photosensitive drum mounting mechanism according to claim 1, wherein at least one of said large diameter portions provided on each of said flange members is formed integrally with said flange member.