JP2012220626A - Photoreceptor drum unit and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoreceptor drum unit that prevents a photoreceptor drum from swaying in a direction orthogonal to an axial direction thereof when the photoreceptor drum is rotated so as to suppress the occurrence of variation in image density in the axial direction of the photoreceptor drum, as well as an image forming apparatus.SOLUTION: An outer circumferential groove 50d is formed at a base part of a cylindrical part 50B along a circumferential direction of the cylindrical part 50B so that rigidity of the base part of the cylindrical part 50B is made lower than that of a portion excluding the base part of the cylindrical part 50B so as to bend the cylindrical part 50B with respect to a flange part 50A in a direction substantially orthogonal to an axial direction of a driving shaft 44 in such a manner that deviation between a central shaft A1 of through holes 50a, 43a and a central shaft of a through hole 45a of a power transmission member 45 is absorbed.

Description

  The present invention relates to a photosensitive drum unit and an image forming apparatus, and relates to, for example, a photosensitive drum unit including a photosensitive drum that carries a toner image, and an image forming apparatus such as a printer, a facsimile, and a copying machine including the photosensitive drum unit. .

  2. Description of the Related Art Image forming apparatuses such as printers, facsimile machines, and copiers use a photosensitive drum unit that includes a photosensitive drum that carries an image to be recorded on a recording sheet. The photosensitive drum carries an electrostatic latent image corresponding to the read image, and the electrostatic latent image is visualized with toner.

  Around the photosensitive drum, there are a charging unit for forming an electrostatic latent image on the photosensitive drum, a developing unit for visualizing the electrostatic latent image formed on the photosensitive drum, and a toner image formed on the photosensitive drum. A transfer belt or the like to be transferred is installed, and the toner image transferred from the developing unit to the photosensitive drum is transferred from the photosensitive drum to the recording paper via the transfer belt.

  For this reason, if a fluctuation in the rotational torque of the photosensitive drum occurs and a speed fluctuation occurs in the photosensitive drum, the image expands and contracts, leading to a decrease in image quality, and the quality of the image transferred to the recording medium deteriorates. End up.

Further, when the photosensitive drum rotates when the photosensitive drum rotates at right angles to the axial direction, if the developing portion is in contact with the photosensitive drum, the photosensitive drum has a uniform surface in the axial direction on the developing portion. If the developing unit cannot contact with the pressure and is not contacted with the photosensitive drum, the gap between the developing unit and the photosensitive drum is not uniform in the axial direction. The point also leads to a decrease in image quality.
Therefore, it is necessary to increase the positioning accuracy of the photosensitive drum in order to prevent the photosensitive drum from being shaken perpendicular to the axial direction.

  Conventionally, as a photosensitive drum unit capable of increasing the positioning accuracy of the photosensitive drum while suppressing fluctuations in the speed of the photosensitive drum, for example, the one shown in FIG. 7 is known (see, for example, Patent Document 1). .

  In FIG. 7, the photosensitive drum 1 includes flange members 2 and 3 at both ends in the axial direction, and the drive shaft 4 is inserted into the through holes 2 a and 3 a of the flange members 2 and 3. Yes. The drive shaft 4 is rotationally driven by a motor 5, and the drive shaft 4 is rotatably supported on the image forming apparatus main body 10 by bearings 6 and 7.

  Therefore, the through holes 2a and 3a are formed in the flange members 2 and 3 so that the center lines A of the through holes 2a and 3a are on the same axis, and the photosensitive drum 1 is connected to the image forming apparatus via the drive shaft 4. By positioning on the main body 10, the positioning accuracy of the photosensitive drum 1 can be improved.

  Therefore, when the photosensitive drum 1 rotates, the photosensitive drum 1 is prevented from swinging in a direction orthogonal to the axial direction, and for example, the gap between the photosensitive drum and the developing unit is made uniform in the axial direction. it can.

  The drive shaft 4 is inserted into the through hole 8a of the power transmission member 8, and the power transmission member 8 is fixed to the power transmission member 8 by caulking or the like. Further, the flange member 2 is provided with a cylindrical portion 2b protruding in the axial direction, and the outer peripheral portion of the power transmission member 8 is serrated to the inner peripheral portion of the cylindrical portion 2b.

  For this reason, the photosensitive drum 1 is rotationally driven by the drive shaft 4 so that the rotational torque of the motor 5 is transmitted from the power transmission member 8 via the cylindrical portion 2b.

  Further, since the outer peripheral portion of the power transmission member 8 is serrated and fitted to the inner peripheral portion of the cylindrical portion 2b, the photosensitive drum 1 does not generate play in the rotation direction and the direction orthogonal to the rotation direction. Therefore, fluctuations in the rotational torque of the photosensitive drum 1 do not occur, speed fluctuations can be prevented, and image expansion and contraction can be prevented.

  In such a conventional photosensitive drum unit, since the outer peripheral portion of the power transmission member 8 is serrated to the inner peripheral portion of the cylindrical portion 2b, the rotational direction and the rotational direction of the photosensitive drum 1 are substantially orthogonal. No backlash occurs in the direction of

  However, since the photosensitive drum 1 and the drive shaft 4 are connected to the through holes 2a and 3a of the flange members 2 and 3 and the through holes 8a of the power transmission member 8 in total, there are three places. As shown in FIG. 8, if the central axis B of the through hole 8 a of the power transmission member 8 is not provided coaxially with respect to the central axis A of the through holes 2 a and 3 a of the flange members 2 and 3, the flange member The drive shaft 4 bends by the amount of deviation between the central axis A of the through-holes 2a and 3a and the central axis B of the through-hole 8a of the power transmission member 8, and the first through-hole and the second through-hole May not be located on the same axis.

  As a result, when the photosensitive drum 1 is rotated, the photosensitive drum 1 is swung in a direction orthogonal to the axial direction. For example, the gap between the photosensitive drum 1 and the developing unit cannot be made uniform in the axial direction. There is a risk of fluctuations in image density.

  Further, in order to prevent the photosensitive drum 1 from swinging in a direction perpendicular to the axial direction when the photosensitive drum 1 rotates, the center axis A of the through holes 2a and 3a of the flange members 2 and 3 and the power transmission member 8 are used. In order to make the center axis B of the through-hole 8a coaxial, it is necessary to strictly manage the processing accuracy of the flange members 2, 3 and the power transmission member 8, and the manufacturing work of the photosensitive drum unit becomes troublesome. End up.

  The present invention has been made to solve such a problem, and prevents the photosensitive drum from swinging in a direction perpendicular to the axial direction when the photosensitive drum rotates, thereby reducing the image density in the axial direction of the photosensitive drum. It is an object of the present invention to provide a photosensitive drum unit and an image forming apparatus that can suppress the occurrence of fluctuations.

  In order to achieve the above object, a photosensitive drum unit of the present invention has a cylindrical photosensitive drum and a first flange member attached to both ends in the axial direction of the photosensitive drum and having a first through hole. And a second flange member in which a second through hole is formed, and is inserted into the first through hole and the second through hole to penetrate the inside of the photosensitive drum, and is also supported by the image forming apparatus main body. A drive shaft rotatably supported through the flange, and the first flange member includes a flange portion having the first through hole, and a cylindrical portion protruding from the flange portion in the axial direction of the drive shaft And a power transmission member having a through-hole fixed to the outer peripheral portion of the drive shaft and serration-fitting to the cylindrical portion, wherein the cylindrical portion is in contact with the flange portion. Said It is configured to flex axially in a direction substantially perpendicular to the shaft.

The photosensitive drum unit is configured so that the cylindrical portion bends in a direction substantially orthogonal to the axial direction of the drive shaft with respect to the flange portion. Therefore, the first through hole and the second flange portion of the first flange portion are provided. The cylindrical portion is bent with respect to the flange portion so as to absorb the deviation between the center axis of the second through hole and the center axis of the through hole of the power transmission member.
For this reason, it is possible to prevent the drive shaft from being bent in a direction perpendicular to the axial direction, and to make the central axis of the drive shaft straight, and the first through hole and the second flange portion of the first flange portion. The center axis of the second through hole can be coaxial.

  Therefore, the processing accuracy of the first and second flange members and the power transmission member is previously set so that the first and second through holes of the first and second flange members are coaxial with the through hole of the power transmission unit. It is possible to prevent the photosensitive drum from swinging in the direction perpendicular to the axial direction when the photosensitive drum rotates. As a result, for example, the gap between the photosensitive drum and the developing unit can be made uniform in the axial direction, and the occurrence of fluctuations in image density in the axial direction of the photosensitive drum can be suppressed.

Further, the photosensitive drum unit of the present invention is configured such that a groove is formed along the circumferential direction of the cylindrical portion at the proximal end portion in the protruding direction of the cylindrical portion.
In this photosensitive drum unit, since the groove is formed in the projecting direction base end portion of the cylindrical portion along the circumferential direction of the cylindrical portion, the rigidity of the projecting direction base end portion of the cylindrical portion can be reduced. The cylindrical portion is bent with respect to the flange portion so as to absorb the deviation between the central axis of the first through hole of the flange portion and the second through hole of the second flange portion and the central axis of the through hole of the power transmission member. I can do it.
For this reason, it is possible to prevent the drive shaft from being bent in a direction perpendicular to the axial direction, and to make the central axis of the drive shaft straight, and the first through hole and the second flange portion of the first flange portion. The center axis of the second through hole can be coaxial.

  In the photosensitive drum unit of the present invention, the flange portion and the cylindrical portion are made of different materials, and the rigidity of the cylindrical portion is lower than the rigidity of the flange portion.

In this photosensitive drum unit, the flange portion and the cylindrical portion are made of different materials, and the rigidity of the cylindrical portion is lower than the rigidity of the flange portion. Therefore, the first through hole and the second flange portion of the first flange portion. The cylindrical portion can be bent with respect to the flange portion so as to absorb the deviation between the central axis of the second through hole and the central axis of the through hole of the power transmission member.
For this reason, it is possible to prevent the drive shaft from being bent in a direction perpendicular to the axial direction, and to make the central axis of the drive shaft straight, and the first through hole and the second flange portion of the first flange portion. The center axis of the second through hole can be coaxial.

  Further, in the photosensitive drum unit of the present invention, a groove is formed along the circumferential direction of the cylindrical portion at the base end portion in the protruding direction of the cylindrical portion.

In this photosensitive drum unit, the rigidity of the cylindrical portion is lower than the rigidity of the flange portion, and a groove is formed along the circumferential direction of the cylindrical portion at the proximal end portion in the protruding direction of the cylindrical portion. The rigidity of the direction base end portion can be further reduced, and the protruding direction base end portion of the cylindrical portion can be bent more easily.
For this reason, it is possible to prevent the drive shaft from being bent in a direction perpendicular to the axial direction, and to make the central axis of the drive shaft straight, and the first through hole and the second flange portion of the first flange portion. The center axis of the second through hole can be coaxial.

  The image forming apparatus of the present invention includes the above-described photosensitive drum unit, an image forming unit that forms a toner image on the photosensitive drum, and a transfer unit that transfers the toner image formed on the photosensitive drum to a recording medium. It is comprised from what provided.

  In this image forming apparatus, the first and second flange members and the power transmission are previously arranged so that the first and second through holes of the first and second flange members and the through hole of the power transmission unit are coaxial. It is unnecessary to strictly manage the processing accuracy of the member, and it is possible to prevent the photosensitive drum from swinging in a direction orthogonal to the axial direction when the photosensitive drum rotates. As a result, for example, the gap between the photosensitive drum and the developing unit can be made uniform in the axial direction, and the occurrence of fluctuations in image density in the axial direction of the photosensitive drum can be suppressed.

  As described above, it is possible to prevent the fluctuation of the image density in the axial direction of the photosensitive drum by preventing the photosensitive drum from swinging in the direction orthogonal to the axial direction when the photosensitive drum rotates. A photoconductor drum unit and an image forming apparatus that can be provided can be provided.

1 is a diagram showing a first embodiment of a photosensitive drum unit and an image forming apparatus according to the present invention, and is a schematic configuration diagram of a copying machine. 1 is a diagram illustrating a first embodiment of a photosensitive drum unit and an image forming apparatus according to the present invention, and is a cross-sectional view of the photosensitive drum unit. 1 is a diagram illustrating a first embodiment of a photosensitive drum unit and an image forming apparatus according to the present invention, and is an exploded perspective view of a first flange member and a power transmission member. FIG. 1 is a diagram illustrating a first embodiment of a photosensitive drum unit and an image forming apparatus according to the present invention, and is a cross-sectional view of a first flange member. FIG. FIG. 4 is a diagram illustrating a second embodiment of a photosensitive drum unit and an image forming apparatus according to the present invention, and is a cross-sectional view of a first flange member. It is a figure which shows 2nd Embodiment of the photosensitive drum unit and image forming apparatus which concern on this invention, and is sectional drawing of the 1st flange member which has another structure. It is sectional drawing of the conventional photoconductor drum unit. It is a figure which shows the shift | offset | difference of the center axis | shaft of the through-hole of the flange member of the conventional photoreceptor drum unit, and the center axis | shaft of the through-hole of a power transmission member.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1 to 4 are diagrams showing a first embodiment of a photosensitive drum unit and an image forming apparatus according to the present invention, and show an example applied to a copying machine as an image forming apparatus. The image forming apparatus can be applied to a printer apparatus, a facsimile apparatus, or a multifunction machine having a printer function and a facsimile function.

First, the configuration will be described.
In FIG. 1, a copying machine 11 includes a document reading unit 12 that reads an image on a document, and a sheet feeding unit 14 that feeds the uppermost recording sheet 13a among a plurality of recording sheets 13 as a stacked recording medium. The image forming unit 15 that forms an image read by the document reading unit 12 on the recording paper 13a fed by the paper feeding unit 14 and the unfixed image formed on the recording paper 13a by the image forming unit 15 are fixed. And a fixing device 16. In the copying machine 11 of the present embodiment, the image forming unit 15 and the paper feeding unit 14 can be divided.

  The image forming unit 15 includes four image forming units 17 (17Y (yellow), 17C (cyan), 17M (magenta), 17Bk (black)), a transfer belt 18 as a transfer unit, and an exposure device 19. is doing.

  The image forming units 17Y, 17C, 17M, and 17Bk are arranged around the photosensitive drum 20 and the photosensitive drum 20 that are driven to rotate in the clockwise direction and function as an image carrier (20Y, 20C, 20M, and 20Bk). The charging unit 21, the developing unit 22, the cleaning unit 23, and the like are configured to form images of different color toners, that is, toner images.

A photosensitive layer is provided on the outer peripheral portion of the photosensitive drum 20, and a light beam indicated by a broken line emitted from the exposure device 19 is spot-irradiated on the outer peripheral surface of the photosensitive drum 20, whereby the photosensitive drum 20. An electrostatic latent image corresponding to image information is written on the outer peripheral surface.
The charging unit 21 is configured to uniformly charge the outer peripheral surface of the photosensitive drum 20, and a non-contact type that is charged by making it non-contact with the photosensitive drum 20 is employed.

  The developing unit 22 supplies toner to the outer peripheral surface of the photosensitive drum 20, and the supplied toner adheres to the electrostatic latent image written on the outer peripheral surface of the photosensitive drum 20, thereby The electrostatic latent image is visualized as a toner image, and a non-contact type that adheres toner without contacting the photosensitive drum 20 is employed.

  The cleaning unit 23 is configured to remove residual toner adhering to the outer peripheral surface of the photosensitive drum 20, and a brush contact type in which a brush is brought into contact with the outer peripheral surface of the photosensitive drum 20 is employed. .

  The transfer belt 18 is constituted by an endless belt formed with a resin film or rubber as a base, and a toner image formed on the photosensitive drum 20 is transferred thereto. Further, the toner image transferred to the transfer belt 18 is transferred as an unfixed image onto the recording paper 13 a by the transfer roller 24.

  The exposure device 19 includes image data input from a terminal such as a personal computer or a word processor connected via a network, a FAX transmitter connected via a telephone line, or an image of a document read by the document reading unit 12. Is converted into a light source driving signal, and the semiconductor laser in each laser light source unit is driven based on the converted signal to emit a light beam.

  The paper feeding unit 14 has a paper feeding device 25 as a sheet material separating and feeding device, and the paper feeding device 25 is a recording located at the top of a plurality of recording papers 13 stacked on a paper feeding tray. It has a separation unit 26 that sucks the paper 13a and feeds it to the downstream side in the transport direction.

The recording paper 13 a separated by the paper feeding device 25 is transported into the transport path 27, and the recording paper 13 a transported to the transport path 27 is further transported by the transport roller pair 28. It has become.
Further, the toner image formed by the image forming unit 15 is transferred to the recording paper 13 a conveyed by the conveying roller pair 28 by the transfer roller 29.

  The fixing device 16 thermally transfers the toner image transferred to the recording paper 13 a by the transfer roller 29.

Further, the copying machine 11 includes a paper discharge tray 30, and the recording paper 13 a fixed by the fixing device 16 is conveyed by a paper discharge roller pair 31 and discharged to the paper discharge tray 30. .
In the present embodiment, the exposure device 19, the charging unit 21, the developing unit 22, and the cleaning unit 23 constitute an image forming unit.

  On the other hand, as shown in FIG. 2, the photosensitive drum 20 constitutes a part of the photosensitive drum unit 41.

  The photosensitive drum unit 41 includes the photosensitive drum 20, flange members 42 and 43, a drive shaft 44, a power transmission member 45, a spring 46, bearings 47a and 47b, a joint portion 48, and a motor 49.

  The flange member 42 constitutes a first flange member, and is attached to the photosensitive drum 20 by adhesion or the like so as to close one end portion in the axial direction of the photosensitive drum 20. The flange member 43 constitutes a second flange member, and is attached to the photosensitive drum 20 by adhesion or the like so as to close the other axial end portion of the photosensitive drum 20.

  The flange member 42 includes a flange portion 50A in which a through hole 50a as a first through hole is formed, and a cylindrical portion 50B that protrudes in the axial direction of the drive shaft 44 from the flange portion 50A.

  A through hole 43a as a second through hole is formed in the flange member 43, and the drive shaft 44 passes through the inside of the photosensitive drum 20 through the through holes 50a and 43a. It is positioned in the through holes 50a and 43a.

  The drive shaft 44 is rotatably supported by a main body 11a of the copying machine 11 as a main body of the image forming apparatus via bearings 47a and 47b. The main body 11a of the copying machine 11 includes a casing constituting the main body 11a and a part such as a partition plate provided in the casing.

  A joint portion 48 is fixed to one end portion of the drive shaft 44 by caulking or the like, and the joint portion 48 is attached to an output shaft 49a of a motor 49 so as to be integrally rotatable with the output shaft 49a.

  In addition, the drive shaft 44 passes through the through hole 45a of the power transmission member 45, and the power transmission member 45 rotates integrally with the drive shaft 44 by being fixed to the drive shaft 44 by caulking.

  As shown in FIGS. 2 and 3, a taper 45b is formed on the outer periphery of the power transmission member 45, and a male serration groove 45c is formed on the taper 45b.

  Further, a taper 50b that is inclined in the same direction as the taper 45b of the power transmission member 45 is formed on the inner peripheral portion of the cylindrical portion 50B, and a female serration groove 50c that meshes with the male serration groove 45c is formed on the taper 50b. Has been. That is, the power transmission member 45 is serrated to the inner peripheral portion of the cylindrical portion 50B.

  For this reason, the flange member 42 and the power transmission member 45 are free from backlash between the rotation direction of the drive shaft 44 and the direction substantially orthogonal to the rotation direction. No backlash occurs in the direction substantially orthogonal to the rotation direction of the drive shaft 44.

  The spring 46 is interposed between the bearing 47a and the flange member 43, and the spring 46 biases the photosensitive drum 20 to the right in FIG. The power transmission member 45 is fitted to the cylindrical portion 50B so that there is no backlash between the tapers 45b and 50b. For this reason, the drive shaft 44 and the photosensitive drum 20 do not move relative to each other in the axial direction of the drive shaft 44.

  Further, an outer peripheral groove 50d as a groove is formed in the base portion of the cylindrical portion 50B along the circumferential direction of the cylindrical portion 50B (see FIG. 4). For this reason, the rigidity of the base portion of the cylindrical portion 50B is lower than the portion excluding the base portion of the cylindrical portion 50B, and the cylindrical portion 50B is a direction substantially orthogonal to the axial direction of the drive shaft 44 with respect to the flange portion 50A. To bend. The direction substantially orthogonal to the drive shaft 44 includes a direction orthogonal to the drive shaft 44 by 90 ° and a direction around 90 °.

Next, the operation will be described.
In the photosensitive drum unit 41 of the present embodiment, when the motor 49 is rotationally driven, rotational torque is transmitted from the output shaft 49 a of the motor 49 to the drive shaft 44 via the joint portion 48.

  Since the power transmission member 45 and the cylindrical portion 50B are serrated through the male serration groove 45c and the female serration groove 50c, the rotational torque of the drive shaft 44 is photosensitive via the power transmission member 45 and the flange member 42. Rotational torque is transmitted to the body drum 20, and the photosensitive drum 20 and the drive shaft 44 rotate together.

  Further, when the photosensitive drum 20 rotates, the power transmission member 45 and the cylindrical portion 50B are serrated through the male serration groove 45c and the female serration groove 50c, so that the flange member 42 and the power transmission member 45 does not cause backlash in the direction of rotation of the drive shaft 44 and the direction substantially orthogonal to the direction of rotation, and therefore the speed fluctuation of the photosensitive drum 20 due to the fluctuation of the rotational torque of the photosensitive drum 20 does not occur.

  On the other hand, the positioning positions of the photosensitive drum 20 and the drive shaft 44 are three in total, that is, the through holes 50a and 43a of the flange members 42 and 43 and the through holes 45a of the power transmission member 45, and the through holes 50a and 43a Unless the processing accuracy with the through hole 45a of the power transmission member 45 is strictly managed, the central axis of the through hole 45a of the power transmission member 45 is not coaxial with the central axis A1 of the through holes 50a and 43a.

In the present embodiment, by forming the outer peripheral groove 50d along the circumferential direction of the cylindrical portion 50B in the base portion of the cylindrical portion 50B, the rigidity of the base portion of the cylindrical portion 50B is lower than the portion excluding the base portion of the cylindrical portion 50B. Therefore, the cylindrical portion 50B can be connected to the flange portion 50A with respect to the drive shaft 44 so as to absorb the deviation between the central axis A1 of the through holes 50a and 43a and the central axis of the through hole 45a of the power transmission member 45. It can be bent in a direction substantially perpendicular to the axial direction.
For this reason, it is possible to prevent the drive shaft 44 from being bent in a direction orthogonal to the axial direction and to make the central axis of the drive shaft 44 straight, and to make the central axis A1 of the through holes 50a and 43a coaxial. Can do.

  Therefore, the processing accuracy of the flange members 42, 43 and the power transmission member 45 is strictly controlled so that the through holes 50a, 43a of the flange members 42, 43 and the through hole 45a of the power transmission member 45 are coaxial. Unnecessary, it is possible to prevent the photosensitive drum 20 from swinging in a direction orthogonal to the axial direction of the drive shaft 44 when the photosensitive drum 20 rotates.

  As a result, the gap between the photosensitive drum 20 and the developing unit 22 can be made uniform over the axial direction, and fluctuations in image density in the axial direction of the photosensitive drum 20 can be suppressed.

  In addition to preventing fluctuations in image density, as described above, fluctuations in the rotational torque of the photosensitive drum 20 are prevented to prevent speed fluctuations in the photosensitive drum 20. Can do. For this reason, it is possible to prevent the expansion and contraction of the image from occurring, and it is possible to prevent the quality of the image transferred to the recording paper 13 from deteriorating.

(Second Embodiment)
FIG. 5 is a diagram showing a second embodiment of the photosensitive drum unit and the image forming apparatus according to the present invention. The same reference numerals as in the first embodiment denote the same reference numerals, and a description thereof will be omitted. .
In FIG. 5, a flange member 61 as a first flange member includes a flange portion 61 </ b> A in which a through hole 61 a as a first through hole through which the drive shaft 44 is inserted, and the flange portion 61 </ b> A to the drive shaft 44. And a cylindrical portion 61B protruding in the axial direction. The flange portion 61A and the cylindrical portion 61B are integrally formed by insert molding.

A taper 61b that is inclined in the same direction as the taper 45b of the power transmission member 45 is formed on the inner peripheral portion of the cylindrical portion 61B. A female serration groove 61c that meshes with the male serration groove 45c is formed on the taper 61b. Yes. That is, the power transmission member 45 is serrated to the inner peripheral portion of the cylindrical portion 61B.
The flange portion 61A is made of a metal, and the cylindrical portion 61B is made of a resin having a rigidity lower than that of the metal.

  In the present embodiment, since the rigidity of the cylindrical portion 61B is lower than the rigidity of the flange portion 61A, the deviation between the central axis A1 of the through holes 61a and 43a and the central axis of the through hole 45a of the power transmission member 45 is prevented. The cylindrical portion 61B can be bent in a direction substantially orthogonal to the axial direction of the drive shaft 44 with respect to the flange portion 61A so as to absorb.

  For this reason, it is possible to prevent the drive shaft 44 from being bent in a direction orthogonal to the axial direction and to make the central axis of the drive shaft 44 straight, and to make the central axis A1 of the through holes 61a and 43a coaxial. Can do.

  Moreover, as shown in FIG. 6, you may make it form the outer peripheral groove | channel 61d as a groove | channel along the circumferential direction of the cylindrical part 61B in the base part of the cylindrical part 61B. In this way, the rigidity of the base portion of the cylindrical portion 61B can be further reduced, and the deviation between the central axis A1 of the through holes 61a and 43a and the central axis of the through hole 45a of the power transmission member 45 is absorbed. Further, the cylindrical portion 61B can be further bent with respect to the flange portion 61A in a direction substantially orthogonal to the axial direction of the drive shaft 44.

  In each of the above embodiments, the copying machine 11 is provided with the non-contact developing unit 22 that attaches the toner without contacting the photosensitive drum 20, but the copying machine 11 includes the photosensitive member. A contact-type developing unit that attaches toner by contacting the drum 20 may be provided.

  In this case, the contact pressure between the photosensitive drum 20 and the developing unit can be made uniform in the axial direction, and the occurrence of fluctuations in image density in the axial direction of the photosensitive drum 20 can be suppressed. it can.

  As described above, the photosensitive drum unit and the image forming apparatus according to the present invention prevent the photosensitive drum from swinging in a direction orthogonal to the axial direction when the photosensitive drum rotates, and image in the axial direction of the photosensitive drum. It has the effect of suppressing the occurrence of density fluctuations, such as a photosensitive drum unit including a photosensitive drum that carries a toner image, and a printer device, a facsimile, a copying machine, and the like including the photosensitive drum unit. It is useful as an image forming apparatus.

11 Copying machine (image forming device)
11a body (image forming apparatus body)
13 Recording paper (recording medium)
18 Transfer belt (transfer section)
19 Exposure device (image forming unit)
20 Photosensitive drum 21 Charging unit (image forming unit)
22 Development section (image forming section)
23 Cleaning unit (image forming unit)
41 Photosensitive drum unit 42 Flange member (first flange member)
43 Flange member (second flange member)
43a Through hole (second through hole)
44 Drive shaft 45 Power transmission member 45a Through hole 47a, 47b Bearing 50A, 61A Flange part 50B, 61B Cylindrical part 50a, 61a Through hole (first through hole)
50d, 61d Peripheral groove (groove)

Japanese Patent No. 3968199

Claims (5)

A cylindrical photosensitive drum;
A first flange member attached to both ends of the photosensitive drum in the axial direction and having a first through hole; and a second flange member having a second through hole;
A drive shaft that is inserted through the first through hole and the second through hole and passes through the interior of the photosensitive drum, and is rotatably supported by the image forming apparatus main body via a bearing;
The first flange member includes a flange portion having the first through-hole and a cylindrical portion protruding from the flange portion in the axial direction of the drive shaft;
A photosensitive drum unit having a through-hole fixed to the outer peripheral portion of the drive shaft, and a power transmission member serrated and fitted to the cylindrical portion;
The photosensitive drum unit, wherein the cylindrical portion is configured to bend in a direction substantially orthogonal to an axial direction of the drive shaft with respect to the flange portion.   The photosensitive drum unit according to claim 1, wherein a groove is formed along a circumferential direction of the cylindrical portion at a base end portion in a protruding direction of the cylindrical portion.   2. The photosensitive drum unit according to claim 1, wherein the flange portion and the cylindrical portion are made of different materials, and the rigidity of the cylindrical portion is lower than the rigidity of the flange portion.   The photosensitive drum unit according to claim 3, wherein a groove is formed along a circumferential direction of the cylindrical portion at a base end portion in a protruding direction of the cylindrical portion.   5. The photosensitive drum unit according to claim 1, an image forming unit that forms a toner image on the photosensitive drum, and a transfer that transfers the toner image formed on the photosensitive drum to a recording medium. And an image forming apparatus.

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