JP4006912B2 - Photosensitive drum support mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a support mechanism for a photosensitive drum of an image forming apparatus, and more particularly to a support mechanism capable of exhibiting a function for preventing uneven rotation of the photosensitive drum.
[0002]
[Prior art]
In an image forming apparatus such as a printer or a copier using a photosensitive drum, an electrostatic latent image is formed by writing an image on the photosensitive drum arranged in the image forming unit by an image writing device, and a developing device. The electrostatic latent image is visualized as a toner image by supplying toner. The toner image is transferred to a sheet, and the sheet carrying the toner image is fixed through a fixing device to create a copy. The photosensitive drum needs to be configured to rotate at a substantially constant speed. If the rotational speed is uneven, there is a problem in that the copy image quality is adversely affected. Therefore, in order to suppress the rotation unevenness of the photosensitive drum, a method is used in which felt or foam is provided as a braking member on the outer peripheral surface of the flange of the photosensitive drum and friction torque is generated between the inner peripheral surface of the drum gear. It has been.
[0003]
[Problems to be solved by the invention]
However, when a member that generates the friction torque is used, the brake member is arranged along the inner peripheral surface of the drum gear. Therefore, the diameter of the brake member is determined by the diameter of the inner peripheral surface of the drum gear. When the shaft is bent or the photosensitive drum is deformed, the amount of deformation of the braking member is larger than when the braking member is disposed at a position close to the drum shaft axis so that a constant friction torque cannot be obtained. The problem occurs.
[0004]
The present invention is intended to solve the above-described problems. Even when the drum shaft is bent or the photosensitive drum is deformed, the braking member is uniformly deformed, thereby obtaining a stable friction torque. It is an object of the present invention to provide a support mechanism for such a photosensitive drum.
[0005]
[Means for Solving the Problems]
The present invention provides a flange member having a large-diameter cylindrical portion whose outer peripheral surface is fitted to an inner peripheral surface of a photosensitive drum, and a small-diameter cylindrical portion rotatably provided on a drum shaft fixedly supported by the frame, A base body having a ring-shaped protrusion inserted between the tube portion and the small-diameter tube portion and fixedly held by the frame; an elastic ring-shaped braking member inserted between the ring-shaped protrusion and the small-diameter tube portion; characterized in that it comprises a. When the brake member is provided along the inner peripheral surface of the drum gear as in the conventional example, the diameter of the brake member is determined by the diameter of the inner peripheral surface of the drum gear, and when the drum shaft bends, it is separated from the axis of the drum shaft. As the amount of deformation of the braking member increases, the amount of deformation can be reduced by disposing the braking member near the shaft of the photosensitive drum. Therefore, a certain amount of crushing occurs in the braking member, the parallelism between the inner and outer peripheral surfaces of the elastic ring-shaped braking member and the corresponding cylindrical surface can be maintained constant, and the friction torque is also substantially constant. Drum rotation can be obtained.
[0006]
The invention of claim 2 is characterized in that a gap is formed between an outer peripheral surface of the inner peripheral surface and the annular projection of the large-diameter cylindrical portion. Then, by providing a space between the drum gear inner peripheral surface and the support flange, the deformation of the braking member is allowed and the amount of deformation of the braking member can be reduced.
[0007]
The invention according to claim 3 is characterized in that the flange member , the base body, and the elastic ring-shaped braking member are provided on a drum drum side of the photosensitive drum. Therefore, even if the drum gear is deformed, the drum can be stably rotated by the braking member .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The photosensitive drum support mechanism of the present invention will be described with reference to the illustrated example. FIG. 1 is a cross-sectional view showing the structure of the end of the photoreceptor assay 1, FIG. 2 is a longitudinal cross-sectional view taken along the line AA, and FIG. 3 is an exploded perspective view. As shown in FIG. 1, in the photoreceptor assay 1, a photoreceptor drum 10 is rotatably provided on a drum shaft 4 fixedly supported on a frame 2. In the example of the photosensitive drum 10, a configuration in which the drum gear 12 is provided at one end portion of the photosensitive drum 10 is illustrated, and the other end portion of the photosensitive drum 10 that is not illustrated is the drum gear. It is possible to arrange and configure only a shaft support member having a symmetrical shape with respect to the flange member 13 without providing the flange member 13. The photosensitive drum 10 and the drum gear 12 can each be constituted of plastic or metal like the photosensitive drum of an image forming apparatus generally used in the past, and the drum gear 12 is flanged. It is also possible to connect and integrate through the member 13.
[0009]
The end of the photosensitive drum 10 and the drum gear 12 are supported by a flange member 13 disposed on the inner surface thereof, and the flange member 13 is provided so as to be rotatable with respect to the drum shaft 4. The flange member 13 can be made of a metal or a plastic material. A small-diameter cylindrical portion 17 (a shaft holding cylindrical portion) is protruded from the base member 14 so as to surround the drum shaft 4 on the frame 2 side. Arranged so that the outer peripheral surface of the large-diameter cylindrical portion 15 is fitted to the inner surface of the photosensitive drum 10. Between the large-diameter cylindrical portion 15 and the small-diameter cylindrical portion 17 configured integrally with the base member 14, a ring-shaped space portion into which a base body 20 and a braking member 5 described later can be inserted is formed. The ground plate 19 attached to the inner surface of the photosensitive drum 10 is made of a conductive metal such as copper and is slidable with respect to the drum shaft 4 and is grounded via the drum shaft 4. Yes.
[0010]
The base body 20 disposed in the ring-shaped space portion of the flange member 13 can be made of plastic or metal and protrudes in parallel with the large-diameter cylindrical portion (outer cylindrical portion) 15 of the flange member 13. A ring-shaped protrusion 21 and a base cylinder 24 that protrudes toward the frame 2 and is supported so as to be attached to the drum shaft 4 are integrally configured. Further, an engagement protrusion 25 is provided at the end of the base body 20 on the frame 2 side, and the engagement protrusion 25 is engaged with an engagement part 3 provided on the frame 2 so that a photosensitive drum is provided. Even in the state where the rotation of 10 is transmitted to the base body 20 via the braking member 5, the base body 20 is prevented from rotating and fixedly held.
[0011]
A gap S having a predetermined interval is provided between the inner peripheral surface of the large-diameter cylindrical portion 15 of the flange member 13 and the outer peripheral surface of the ring-shaped protrusion 21 of the base member 20 so that the base member 20 is flanged. A margin for combining with the member 13 is provided. By providing the gap S, as will be described later, even if the shaft is bent and the positional relationship between the two cylindrical members of the flange member 13 and the base member 20 is shifted, the drum shaft The base member 20 held in a fixed state can be provided with a margin so as not to cause an obstacle to the rotation of the flange member 13 and thus the photosensitive drum 10.
[0012]
The small-diameter cylindrical portion 17 of the flange member 13 to which the braking member 5 is attached is pushed so as to be inserted into the annular projection 21 of the base body 20. At this time, the braking member 5 is pressed against the inner peripheral surface 6 by pressing the inner peripheral surface by the force with which the base body 20 presses the small-diameter cylindrical portion 17 via the braking member 5 and the elastic restoring force of the braking member 5 itself. Do not slip. Therefore, it is not necessary to bond the inner peripheral surface 6 to the small diameter cylindrical portion 17 of the flange member 13 with an adhesive or the like. Further, the outer peripheral surface 7 of the braking member 5 is subjected to wear-resistant surface processing such as Teflon (trade name) processing, and the photosensitive drum 10 is made to have a smaller frictional force than the inner peripheral surface 6. With this rotation, the braking member 5 rotates integrally with the photosensitive drum 10, that is, the flange member 13, and the outer peripheral surface of the braking member 5 slides mutually. As a result, an appropriate frictional force can be obtained and wear of the braking member 5 can be suppressed.
[0013]
1 are combined in the state shown in the perspective view of FIG. That is, the braking member 5 is attached to the small diameter cylindrical portion 17 of the flange member 13 provided at the end of the photosensitive drum 10, and the base body 20 is attached so as to contact the side portion of the flange member 13, The ring-shaped protrusion 21 of the base 20 is made to enter the ring-shaped space of the flange member 13. As described above, when the substrate 20 combined with the end of the photosensitive drum 10 is attached to the frame 2, the drum shaft 4 is passed through the shaft hole as shown in FIG. Is fixed to the frame by an arbitrary fixing means. Further, as shown in FIG. 1, the engagement protrusion 25 provided to protrude from the end of the base body 20 is engaged with the engagement part 3 provided on the frame 2, thereby rotating the base body 20. To prevent it.
[0014]
As shown in FIG. 1, in a state where the base body 20 that is non-rotatably supported on the drum shaft 4 and the photosensitive drum 10 to which driving force is applied through the drum gear 12 are combined, between the two members. The intervening braking member 5 exerts a braking action on the rotation of the photosensitive drum 10 so as to prevent the rotation of the photosensitive drum 10 from becoming uneven. The braking member 5 is formed as a ring-shaped member by an elastic body such as an arbitrary soft plastic, rubber, felt or the like, and its inner peripheral surface 6 is an outer peripheral surface of the small-diameter cylindrical portion 17 of the flange member 13. 18 is attached so that the outer peripheral surface 7 is in contact with the inner peripheral surface 22 of the annular projection 21 of the base body 20. Since the small-diameter cylindrical portion 17 of the rotating photosensitive drum 10 is combined without slipping, the flange member 13 rotates with respect to the outer peripheral surface 7 of the braking member 5 together with the photosensitive drum 10. try to.
[0015]
By the way, since the outer peripheral surface 7 of the braking member 5 is subjected to Teflon processing, the frictional resistance is smaller than that of the inner peripheral surface 6. Therefore, the outer peripheral surface 7 of the braking member 5 rotates while the inner peripheral surface 22 of the ring-shaped protrusion 21 slides, so that the photosensitive drum 10 rotates. At this time, the braking action against the rotation of the photosensitive drum 10 is given by the friction between the outer peripheral surface 7 of the braking member 5 and the inner peripheral surface 22 of the annular projection 21. For example, even when the driving force transmitted to the drum gear 12 with respect to the photosensitive drum 10 is uneven, the braking force is applied by the braking member 5 so that the rotational state of the photosensitive drum 10 is increased. Unevenness is prevented from occurring.
[0016]
In addition to the problem of uneven rotation of the photoconductor drum, in the photoconductor assay 1, when a deflection or the like occurs in the drum shaft 4 that supports the photoconductor drum 10, the substrate 20 supported on the shaft end portion On the other hand, it is assumed that the flange member 13 that supports the photosensitive drum 10 with respect to the drum shaft 4 is slightly eccentric. For the problem that the positional relationship between the two cylindrical members is eccentric, the gap S is formed between the base member 20 and the flange member 13 as two members supported by the drum shaft 4. Therefore, the parallelism between the inner peripheral surface 22 of the ring-shaped protrusion 21 of the base 20 and the outer peripheral surface 18 of the small-diameter cylindrical portion 17 is maintained at a degree of deflection of the shaft corresponding to the gap, and stable photosensitivity. A rotation of the body drum 10 is obtained. Of course, when the gap S between the base body 20 and the flange member 13 is eliminated and the outer peripheral surface 23 of the ring-shaped protrusion 21 is in direct contact with the inner peripheral surface 16 of the large-diameter cylindrical portion 15, Then, the photosensitive drum 10 is not operated at a normal position, which affects the rotation of the photosensitive drum 10.
[0017]
When the state in which the gap S is not part of the gap as described above has occurred, the image writing means disposed on the photosensitive drum 10 and a device such as the developing roller of the developing device can operate normally. It will not be. Further, when the drum shaft 4 is deflected more than an allowable state, the photosensitive drum 10 is naturally not smoothly rotated, so that the apparatus is properly operated by other detection means of the image forming apparatus. It is determined that the image forming apparatus is not operating, and the operation of the image forming apparatus is stopped.
[0018]
In the braking member 5 disposed between the flange member 13 and the base body 20, when it is assumed that the drum shaft 4 is bent, the influence of the deflection becomes larger as the drum shaft 4 is separated from the axis. That is, if the braking member 5 is disposed on the drum gear inner peripheral surface 16 that is separated from the drum shaft 4, the amount of deformation becomes large, and the braking member 5 may not be in contact with a part, and a stable braking state can be obtained. Therefore, uneven rotation occurs. On the other hand, the braking member 5 shown in the present embodiment is disposed at a position close to the drum shaft 4, and the drum shaft 4 as when disposed on the inner peripheral surface 16 of the photosensitive drum 10. It is not at a position that is greatly separated from the axis. Further, the outer peripheral surface 18 of the small-diameter cylindrical portion 17 and the inner peripheral surface 22 of the ring-shaped protrusion 21 of the base body 20 provided so as to sandwich the braking member 5 are spaced apart by the thickness of the braking member 5. Therefore, when the restoring force of the braking member 5 having an elastic action and the base body 20 press the flange member 13 via the braking member 5, the inner peripheral surface 6 of the braking member 5 is against the small diameter cylindrical portion 17 of the flange member 13. Is not slippery.
[0019]
In addition, since the two surfaces 22 and 18 facing each other with the braking member 5 interposed therebetween are located close to the axis of the drum shaft 4, for example, even if the drum shaft 4 is bent, the influence is caused by the gap S. Since the two surfaces 22 and 18 are maintained in parallel and the braking force of the braking member 5 is evenly applied, the photosensitive drum 10 can rotate stably. Accordingly, the state in which the photosensitive drum 10 can be normally operated, that is, the other image forming members with respect to the photosensitive drum 10 are in a positional relationship in which they can normally operate, and the other members. When an abnormality detection signal is not output from the brake, it can be determined that the brake operation by the braking member is being executed accurately. When the photosensitive drum is deformed or the deformation (deflection) of the drum shaft 4 is increased, the gap S between the flange member 13 and the base body 20 is not locally removed as described above, and the large-diameter cylinder The inner peripheral surface 16 of the portion 15 and the outer peripheral surface 22 of the annular projection 21 are in direct contact with each other.
[0020]
The photoreceptor assay 1 shown in the above-described embodiment can be applied to an image forming apparatus using an electrophotographic method such as a conventionally used printer or copying machine, or a multifunction machine of a copying machine and a facsimile machine. Is possible. The photosensitive drum 10 and the flange member 13 can be made of any material, and the means for fixing the base 20 to the frame 2 has the same function as the engaging protrusion. If it exists, it can be of any structure. Furthermore, the position where the braking member 5 is disposed is as close as possible to the drum shaft 4 and can be more effective if disposed at a position where the influence of the deflection of the drum shaft 4 is small. Then, by setting the gap between the base body 20 and the flange member 13 to an interval that allows the normal operation range of the photosensitive drum, it is possible to prevent inconvenience in the operation of the apparatus. It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.
[0021]
【The invention's effect】
The device according to the present invention is configured as described above, and by disposing the braking member at a position close to the drum shaft, a certain amount of crushing occurs in the braking member, and the inside and outside of the elastic ring-shaped braking member are formed. Since the parallelism between the peripheral surface and the corresponding cylindrical surface can be maintained constant, and the friction torque is substantially constant, stable rotation of the photosensitive drum can be obtained. When the deflection of the drum shaft occurs, the amount of deformation increases as the distance from the outer periphery of the drum gear increases, and the amount of deformation of the braking member also increases.By disposing the braking member inside the photosensitive drum, The amount of deformation can be reduced. In addition, by providing a gap between the inner peripheral surface of the flange member and the outer peripheral surface of the base body, the amount of crushing can be reduced even if the braking member is deformed. Since the parallelism of the peripheral surface can be maintained, stable rotation of the photosensitive drum can be obtained. Further, by providing a braking mechanism on a flange member having a drum gear formed at the end of the photosensitive drum, the photosensitive drum can be stably rotated even when the drum gear is slightly deformed.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the configuration of a photoreceptor assay.
FIG. 2 is a vertical end view taken along line AA in FIG.
FIG. 3 is an exploded perspective view of a photoreceptor assay.
[Explanation of symbols]
1 photoreceptor assay, 2 frames, 3 locking part,
4 drum shaft, 5 braking member, 6 inner peripheral surface,
7 outer peripheral surface, 10 photosensitive drum, 12 drum gear,
13 flange member, 14 base member, 15 large diameter cylindrical part,
16 inner peripheral surface, 17 small diameter cylindrical portion, 18 outer peripheral surface,
19 ground plate, 20 base, 21 ring-shaped protrusion,
22 inner peripheral surface, 23 outer peripheral surface, 24 base cylinder part,
25 Engagement protrusion.

Claims (3)

A flange member having a large-diameter cylindrical portion whose outer peripheral surface is fitted to an inner peripheral surface of the photosensitive drum, and a small-diameter cylindrical portion rotatably provided on a drum shaft fixedly supported by the frame, the large-diameter cylindrical portion, A base having a ring-shaped protrusion inserted between the small-diameter cylindrical part and fixed to the frame, and an elastic ring-shaped braking member inserted between the ring-shaped protruding part and the small-diameter cylindrical part. A photosensitive drum support mechanism. Photosensitive drum supporting mechanism according to claim 1, characterized in that a gap is formed between an outer peripheral surface of the inner peripheral surface of the large diameter cylindrical portion and the annular projection. 3. The photosensitive drum support mechanism according to claim 1 , wherein the flange member , the base body, and the elastic ring-shaped braking member are provided on a drum drum side of the photosensitive drum.

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