JP2024146966A - Drum unit - Google Patents

Abstract

To provide a drum unit capable of precisely positioning a bearing member to a drum frame.SOLUTION: A drum unit includes: a photoreceptor drum extending in a first direction; a bearing member 60 mounted to one end in a first direction of the photoreceptor drum; and a drum frame having a first through hole 313 into which the bearing member 60 is inserted. The bearing member 60 includes: a drum bearing section 62 for covering one portion of an outer peripheral surface of the photoreceptor drum; a flap 63 for covering the other part; and a first rib 64 projecting toward the outside in a radial direction from an outer peripheral surface of the drum bearing section 62. The flap 63 is positioned with an interval to the drum bearing section 62 in a circumferential direction of the photoreceptor drum, abuts on one end of the photoreceptor drum in a second direction as a radial direction of the photoreceptor drum, and energizes the photoreceptor drum in one of second directions toward the drum bearing section 62. The first rib 64 energizes the bearing member 60 relative to the drum frame.SELECTED DRAWING: Figure 6

Description

This disclosure relates to a drum unit.

Conventionally, electrophotographic image forming devices such as laser printers and LED printers are known. The image forming device has, for example, a developing cartridge having a developing roller for supplying developer, and a drum unit having a photosensitive drum. A conventional image forming device is described, for example, in Patent Document 1. The image forming device in Patent Document 1 has a photosensitive cartridge (drum unit) having a photosensitive drum. The developing cartridge is attached to the photosensitive cartridge. When the developing cartridge is attached to the photosensitive cartridge, the photosensitive drum and the developing roller come into contact with each other.

In this way, in a configuration in which the photosensitive drum and the developing roller are in contact with each other, it is necessary to determine the relative positions of the photosensitive drum and the developing roller with high precision. To achieve this, it is necessary to determine the position of the photosensitive drum in the drum unit with high precision.

Patent document 1 describes a configuration in which flange members are fixed to both axial ends of a photosensitive drum, and the flange members are attached so as to be rotatable relative to bearing members fixed in through holes formed in a drum frame.

JP 2011-64884 A

In the image forming device described in Patent Document 1, the bearing member has a pressing member that presses the flange member in a predetermined pressing direction, thereby positioning the bearing member and the photosensitive drum in the pressing direction.

To achieve more precise positioning, it is necessary to improve the positioning accuracy of the bearing member relative to the drum frame.

The objective of this disclosure is to provide a drum unit that can accurately position the bearing member relative to the drum frame.

The first disclosure of the present application is a drum unit comprising: a photosensitive drum rotatable about a first axis extending in a first direction; a bearing member attached to one end of the photosensitive drum in the first direction; and a drum frame having a through hole penetrating in the first direction and into which the bearing member is inserted, the bearing member having a drum bearing portion covering a part of the outer peripheral surface of the photosensitive drum; a flap positioned at a distance from the drum bearing portion in the circumferential direction of the photosensitive drum and covering another part of the outer peripheral surface of the photosensitive drum, the flap contacting the one end of the photosensitive drum in a second direction, which is the radial direction of the photosensitive drum, and biasing the photosensitive drum in one direction in the second direction toward the drum bearing portion; and a first rib protruding from the outer peripheral surface of the drum bearing portion toward the outside in the radial direction, biasing the bearing member against the drum frame.

The second disclosure of this application is the drum unit of the first disclosure, characterized in that the first rib faces the inner circumferential surface of the through hole in the second direction and is in contact with the inner circumferential surface of the through hole.

The third disclosure of the present application is the drum unit of the second disclosure, characterized in that the first rib has a base end portion that extends radially outward from the outer circumferential surface of the drum bearing portion, and a tip end portion that extends in the second direction from the tip of the base end portion, faces the inner circumferential surface of the through hole in the second direction, and is in contact with the inner circumferential surface of the through hole.

The fourth disclosure of the present application is the drum unit of the third disclosure, characterized in that the tip portion extends from the base end portion in the other direction in the second direction, and the other end portion in the second direction contacts the inner circumferential surface of the through hole.

The fifth disclosure of this application is the drum unit of the second disclosure, characterized in that the first rib has elasticity.

The sixth disclosure of the present application is the drum unit of the third disclosure, characterized in that the through hole has a hole body portion having an inner peripheral surface that faces the outer peripheral surface of the drum bearing portion and the outer peripheral surface of the flap, and a recess that is recessed radially outward from the hole body portion, and the first rib is located within the recess.

The seventh disclosure of the present application is the drum unit of the first disclosure, characterized in that the inner peripheral surface of the through hole includes a first plane and a second plane extending in different directions, and the first plane and the second plane each face the outer peripheral surface of the drum bearing portion and are in contact with the outer peripheral surface of the drum bearing portion.

The eighth disclosure of the present application is the drum unit of the first disclosure, characterized in that the flap has one end furthest in the first direction from the other end of the photosensitive drum in the first direction, the drum bearing portion has one end furthest in the first direction from the other end of the photosensitive drum, and the one end of the drum bearing portion is located between the other end of the photosensitive drum and the one end of the flap in the first direction.

The ninth disclosure of the present application is the drum unit of the first disclosure, characterized in that the flap has one end farthest in the first direction from the other end of the photosensitive drum in the first direction, the drum frame is located around the through hole and has a plane extending in a direction intersecting the first direction, and the plane of the drum frame is located between the other end of the photosensitive drum and the one end of the flap in the first direction.

The tenth disclosure of the present application is the drum unit of the first disclosure, characterized in that the bearing member further has a second rib that protrudes radially outward from the outer circumferential surface of the drum bearing portion and that, together with the first rib, biases the bearing member against the drum frame.

The 11th disclosure of the present application is the drum unit of the 10th disclosure, characterized in that the flap is positioned between the first rib and the second rib in a third direction that intersects the first direction and the second direction.

The twelfth disclosure of the present application is the drum unit of the eleventh disclosure, characterized in that the first rib and the second rib bias the bearing member in one direction in the second direction toward the drum frame.

The thirteenth disclosure of the present application is the drum unit of the tenth disclosure, characterized in that the second rib faces the inner circumferential surface of the through hole in the second direction and is in contact with the inner circumferential surface of the through hole.

The 14th disclosure of the present application is the drum unit of the 13th disclosure, characterized in that the second rib has a base end portion extending radially outward from the outer circumferential surface of the drum bearing portion, and a tip end portion extending in the second direction from the tip of the base end portion, facing the inner circumferential surface of the through hole in the second direction, and contacting the inner circumferential surface of the through hole.

The fifteenth disclosure of the present application is the drum unit of the fourteenth disclosure, characterized in that the tip portion extends from the base portion in the other direction in the second direction, and the other end portion in the second direction contacts the inner circumferential surface of the through hole.

The sixteenth disclosure of the present application is the drum unit of the thirteenth disclosure, characterized in that the second rib has elasticity.

The seventeenth disclosure of the present application is the drum unit of the first disclosure, further comprising a cleaning roller that extends along the first direction and contacts the outer circumferential surface of the photosensitive drum, and the bearing member further includes a cylindrical cleaning roller bearing portion that supports one end of the cleaning roller in the first direction.

The eighteenth disclosure of the present application is a drum unit according to any one of the first disclosures to claim 17, characterized in that the first direction is perpendicular to the second direction.

According to Disclosures 1 to 18, the first rib allows the bearing member to be positioned relative to the through hole in the drum frame.

In addition, according to the third disclosure, no matter where the first rib extends from on the outer circumferential surface of the drum bearing portion, the tip of the first rib can be brought into contact with the frame in the second direction, facing each other. In other words, the degree of design freedom can be increased.

Furthermore, the sixth disclosure allows for even greater design freedom.

In addition, according to the seventh disclosure, the positioning accuracy can be improved compared to when positioning between cylindrical surfaces.

Furthermore, according to the eighth disclosure, by positioning the base end of the flap on one side in the first direction relative to the base end of the drum bearing portion, the length of the flap in the first direction can be increased, thereby increasing the amount of deformation of the flap in the second direction.

According to the 10th to 16th disclosures, the second rib allows the bearing member to be more accurately positioned relative to the through hole of the drum frame.

In addition, according to the 14th disclosure, no matter where the first rib extends from on the outer circumferential surface of the drum bearing portion, the tip of the first rib can be brought into contact with the frame in the second direction, facing each other. In other words, the degree of freedom in design can be increased.

FIG. 1 is a schematic diagram of an image forming apparatus. FIG. 2 is a perspective view of a side plate of a drum frame, a photosensitive drum, a cleaning roller, and a bearing member. FIG. FIG. 2 is a partial exploded perspective view of a side plate of a drum frame, a photosensitive drum, a cleaning roller, and a bearing member. FIG. 4 is a cross-sectional view of the drum unit taken along a line perpendicular to the first direction. FIG. 3 is a cross-sectional view of the drum unit taken along a first direction. FIG.

Embodiments of the present disclosure will be described below with reference to the drawings.

In the following description, the direction in which the photosensitive drum extends is referred to as the "first direction." The radial direction of the photosensitive drum in which the central axis of the photosensitive drum and the flap are aligned is referred to as the "second direction." The first direction and the second direction intersect with each other. More preferably, the first direction and the second direction are perpendicular to each other.

<1. Image forming apparatus>
1 is a schematic diagram of an image forming apparatus 100. The image forming apparatus 100 is an electrophotographic printer. Examples of the image forming apparatus 100 include a laser printer and an LED printer.

As shown in FIG. 1, the image forming device 100 includes a drum unit 1, four developing cartridges 2, and a control unit 10. The four developing cartridges 2 are each attached to the drum unit 1. The drum unit 1 with the four developing cartridges 2 attached is then attached to the image forming device 100.

Figure 2 is a perspective view of the drum unit 1. As shown in Figure 2, the drum unit 1 has a drum frame 30 and four photosensitive drums 40.

The drum frame 30 holds each of the four photosensitive drums 40. The drum frame 30 has a first frame 31 and a second frame 32.

The first frame 31 and the second frame 32 face each other in the first direction. Furthermore, the first frame 31 and the second frame 32 each extend perpendicular to the first direction. The first frame 31 rotatably holds one end of the four photoconductor drums 40 in the first direction. The second frame 32 rotatably holds the other end of the four photoconductor drums 40 in the first direction.

The four photoconductor drums 40 are aligned in a direction perpendicular to the first direction. Two adjacent photoconductor drums 40 are positioned with a gap between them. In this embodiment, the four photoconductor drums 40 are positioned at equal intervals.

The photosensitive drum 40 is rotatable about a first axis 91 extending in a first direction. The photosensitive drum 40 has a cylindrical outer surface centered on the first axis 91. The outer surface of the photosensitive drum 40 is covered with a photosensitive material.

The four developer cartridges 2 include a developer cartridge 2 that contains cyan developer, a developer cartridge 2 that contains magenta developer, a developer cartridge 2 that contains yellow developer, and a developer cartridge 2 that contains black developer. The control unit 10 controls the operation of each unit in the image forming device 100 according to a computer program stored in advance. The image forming device 100 forms an image on a printing sheet using developer supplied from the developer cartridges 2. The developer is, for example, toner.

The developing cartridges 2 are detachable from the drum unit 1 that has the photosensitive drums 40. In this embodiment, four developing cartridges 2 can be attached to the drum unit 1 that has four photosensitive drums 40. However, the number of developing cartridges 2 that can be attached to the drum unit 1 may be one to three, or five or more. In that case, the number of photosensitive drums 40 is the same as the number of developing cartridges 2.

The developing cartridge 2 has a developing roller 21 and a supply mechanism (not shown) that supplies developer to the developing roller 21. The supply mechanism has, for example, a toner storage section and a supply roller that supplies toner from the toner storage section to the developing roller 21. The developing roller 21 is rotatable about a rotation axis that extends in the first direction. The developing roller 21 has a conductive shaft and a cylindrical roller body that covers the periphery of the shaft. The roller body is made of a material, for example, elastic rubber.

When the developing cartridge 2 receives a driving force, developer is supplied to the outer circumferential surface of the developing roller 21. At that time, a bias voltage is applied to the shaft of the developing roller 21, and the supplied developer is charged. Therefore, the developer is attracted to the outer circumferential surface of the developing roller 21 by the electrostatic force between the shaft of the developing roller 21 and the developer.

A portion of the outer peripheral surface of the developing roller 21 is exposed from the housing of the developing cartridge 2. When the developing cartridge 2 is attached to the drum unit 1, the outer surface of the developing roller 21 comes into contact with the photosensitive drum 40. This allows developer to be supplied from the developing roller 21 to the photosensitive drum 40.

The surface of the photoconductor drum 40 is uniformly charged by the charger as the photoconductor drum 40 rotates. The surface of the photoconductor drum 40 is then exposed to light by an exposure unit (not shown) that has an LED light source or a laser light source, and an electrostatic latent image is formed on the surface. Toner is then supplied from the developing roller 21 to the electrostatic latent image formed on the surface of the photoconductor drum 40, and a toner image is formed on the surface of the photoconductor drum 40.

Then, the surface of the photoconductor drum 40 on which the toner image has been formed comes into contact with a recording medium such as printing paper, forming an image on the recording medium.

2. Mounting of the photosensitive drum to the drum frame
<2-1. Structure of the first fixed plate, the bearing member, and the connection points of the photosensitive drum and the cleaning roller>
Fig. 3 is a perspective view showing a state in which a set of photosensitive drum 40 and cleaning roller 50 are attached to the first fixing plate 312 and the second fixing plate 322 of the drum frame 30. Fig. 4 is an exploded perspective view of the first fixing plate 312, the vicinity of one end of the photosensitive drum 40 and the cleaning roller 50 in the first direction, and a bearing member 60. Fig. 5 is a perspective view of the bearing member 60. Fig. 6 is a cross-sectional view of the drum unit 1 in a direction perpendicular to the first direction. Fig. 7 is a cross-sectional view of the drum unit 1 in a plane extending in the first and second directions.

As shown in Figures 2 and 3, the first frame 31 has a first outer plate 311 exposed to the outside and a first fixing plate 312 fixed to the inside of the first outer plate 311. The second frame 32 has a second outer plate 321 exposed to the outside and a second fixing plate 322 fixed to the inside of the second outer plate 321. The first outer plate 311 and the second outer plate 321 are formed, for example, from a resin material. The first fixing plate 312 and the second fixing plate 322 are formed, for example, from a metal.

As shown in Figures 2 to 4, the first outer panel 311, the first fixed panel 312, the second outer panel 321, and the second fixed panel 322 all extend in a direction intersecting the first direction. In this embodiment, the first outer panel 311, the first fixed panel 312, the second outer panel 321, and the second fixed panel 322 extend in a direction perpendicular to the first direction.

As shown in Figures 3 and 4, the first fixing plate 312 has a first through hole 313, a second through hole 314, and a third through hole 315 that penetrate in the first direction. Specifically, the first fixing plate 312 has four first through holes 313, three second through holes 314, and four third through holes 315. Also, as shown in Figure 2, the first outer plate 311 has four outer plate through holes 319 that penetrate in the first direction at positions that overlap with each of the four first through holes 313 in the first direction.

One end of the photosensitive drum 40 and cleaning roller 50 in the first direction is held by the first fixed plate 312 via the bearing member 60. Therefore, this drum unit 1 has four bearing members 60 for four sets of photosensitive drums 40 and cleaning rollers 50.

The bearing member 60 is partially inserted into the first through hole 313 and the second through hole 314 of the first fixed plate 312 and is fixed to the first fixed plate 312. The bearing member 60 also rotatably supports one end of the photosensitive drum 40 and the cleaning roller 50 in the first direction.

As shown in Figures 3 and 4, the photosensitive drum 40 has a cylindrical drum body 41, a first flange member 42, and a first gear 43. The outer peripheral surface of the drum body 41 is covered with a positively charged photosensitive layer. The drum body 41 is cylindrical with a first axis 91 extending in a first direction as its center. The first flange member 42 is inserted into and fixed to one end of the drum body 41 in the first direction.

As shown in FIG. 7, the first flange member 42 has, in order from the side closest to the other end of the photosensitive drum 40 in the first direction, a main body insertion portion 421, a gear portion 422, and a bearing insertion portion 423. The main body insertion portion 421 is a portion that is inserted into one end of the drum main body 41 in the first direction. The outer peripheral surface of the gear portion 422 constitutes the first gear 43.

The first gear 43 is a so-called helical gear. The first gear 43 can rotate about the first shaft 91 together with the drum body 41. As shown in FIG. 4, the outer diameter of the first gear 43 is smaller than the diameter of the outer peripheral surface of the photosensitive drum 40.

The end face of the first flange member 42 at one end in the first direction is provided with a fitting groove 420 that fits with a driving force transmission unit (not shown) provided on the main body of the image forming device 100. The end face of the first flange member 42 having the fitting groove 420 is exposed to the outside of the drum unit 1 through the first through hole 313 of the first fixing plate 312 and the outer plate through hole 319 of the first outer plate 311. When the drum unit 1 is installed in the image forming device 100, the driving force transmission unit fits into the fitting groove 420, and a driving force is transmitted from the driving force transmission unit to the first flange member 42, so that the photosensitive drum 40 can be rotated. The first flange member 42 is formed of, for example, a resin material.

In this embodiment, the first gear 43 is formed as a single part together with the first flange member 42. However, the other parts of the first flange member 42 and the first gear 43 may be separate parts. In that case, it is sufficient that the first gear 43 is fixed to the other parts of the first flange member 42 so that it cannot rotate relative to them. In this way, when a rotational driving force is input to the first flange member 42, the first gear 43 rotates together with the first flange member 42 about the first shaft 91.

The cleaning roller 50 is a member for cleaning the outer peripheral surface of the photosensitive drum 40. The cleaning roller 50 is rotatable about a second shaft 92 extending in the first direction. As shown in FIG. 4, the cleaning roller 50 has a cleaning roller body 51, a second gear 52, and an Oldham coupling 53.

The cleaning roller body 51 has a shaft 511 and a roller body 512. The shaft 511 is a cylindrical member extending along the second axis 92. The shaft 511 is formed of a conductive material. Specifically, the shaft 511 is made of metal or conductive resin. The roller body 512 is made of elastically deformable rubber or sponge. The roller body 512 is fixed to the shaft 511.

The shaft 511 extends in a first direction through the roller body 512. One end of the shaft 511 in the first direction is rotatably supported by the first fixed plate 312 via a bearing member 60. The outer circumferential surface of the roller body 512 contacts the outer circumferential surface of the photosensitive drum 40.

The second gear 52 is located at one end of the shaft 511 in the first direction. Specifically, the second gear 52 is connected to one end of the shaft 511 in the first direction via an Oldham coupling 53. Therefore, the second gear 52 can rotate about the second shaft 92 together with the cleaning roller 50.

The second gear 52 is a so-called helical gear. The second gear 52 meshes with the first gear 43. Therefore, when the first gear 43 rotates, the second gear 52 rotates about the second shaft 92. In addition, the cleaning roller 50 rotates about the second shaft together with the second gear 52.

The Oldham coupling 53 is a joint that connects the second gear 52 and the shaft 511. The Oldham coupling 53 transmits the rotational driving force from the second gear 52 to the shaft 511 while allowing for axial misalignment between the second gear 52 and the shaft 511. This allows the cleaning roller 50 to be pressed toward the photosensitive drum 40 while reducing the repulsive force caused by the meshing of the first gear 43 and the second gear 52. Therefore, the cleaning roller 50 can be brought into contact with the photosensitive drum 40 with a stable pressure. As a result, the outer peripheral surface of the photosensitive drum 40 can be cleaned well by the cleaning roller 50.

The bearing member 60 has a support portion 61, a drum bearing portion 62, a flap 63, a first rib 64, a second rib 65, a cleaning roller bearing portion 66, and a hook 67.

The support portion 61 extends along the first fixed plate 312. As shown in Figures 3 and 7, the support portion 61 is disposed along the outer surface of the first fixed plate 312. In other words, the support portion 61 is located farther from the first fixed plate 312 than the other end of the photoconductor drum 40 in the first direction. The support portion 61 has a circular bearing through hole 610 that penetrates in the first direction.

The drum bearing portion 62 and the flap 63 extend in the first direction from the edge of the bearing through hole 610 of the support portion 61 toward the drum body 41. The base end, which is one end of the drum bearing portion 62 and the flap 63 in the first direction, is connected to the edge of the bearing through hole 610 of the support portion 61. The tip end, which is the other end of the drum bearing portion 62 in the first direction, is located closer to the other end of the photosensitive drum 40 in the first direction than the base end of the drum bearing portion 62. In addition, the tip end of the flap 63 is located closer to the other end of the photosensitive drum 40 in the first direction than the base end of the flap 63.

The drum bearing portion 62 covers a portion of the outer peripheral surface of the photosensitive drum 40. Specifically, the drum bearing portion 62 covers a portion of the circumferential direction of the outer peripheral surface of the bearing insertion portion 423 of the first flange member 42. The drum bearing portion 62 covers more than half of the circumferential direction of the outer peripheral surface of the bearing insertion portion 423.

The flap 63 covers a part of the outer peripheral surface of the photosensitive drum 40. Specifically, the flap 63 covers a part of the outer peripheral surface of the bearing insertion portion 423 of the first flange member 42 in the circumferential direction. The flap 63 has a shorter circumferential distance than the drum bearing portion 62. The flap 63 is positioned at a distance from the drum bearing portion 62 in the circumferential direction of the photosensitive drum 40. The drum bearing portion 62 and the flap 63 form a substantially cylindrical shape that is interrupted in the circumferential direction. Here, as shown in FIG. 6, the radial direction of the photosensitive drum 40, in which the first axis 91, which is the central axis of the photosensitive drum 40, and the flap 63 are aligned, is defined as the second direction. The first axis 91 is located on one side of the second direction relative to the flap 63.

The first rib 64 protrudes from the outer peripheral surface of the drum bearing portion 62 toward the radial outside of the photosensitive drum 40. The first rib 64 is L-shaped when viewed in the first direction. Specifically, the first rib 64 has a first rib base end 641 and a first rib tip end 642. The first rib base end 641 extends from the outer peripheral surface of the drum bearing portion 62 toward the radial outside of the photosensitive drum 40. The first rib tip end 642 extends from the tip of the first rib base end 641 in the other direction in the second direction.

The second rib 65 protrudes from the outer peripheral surface of the drum bearing portion 62 toward the radial outside of the photosensitive drum 40. The second rib 65 is L-shaped when viewed in the first direction. Specifically, the second rib 65 has a second rib base end 651 and a second rib tip end 652. The second rib base end 651 extends from the outer peripheral surface of the drum bearing portion 62 toward the radial outside of the photosensitive drum 40. The second rib tip end 652 extends from the tip of the second rib base end 651 in the other direction in the second direction.

As shown in Figures 3, 6 and 7, the drum bearing portion 62, the flap 63, the first rib 64 and the second rib 65 are inserted into the first through hole 313 of the first fixing plate 312. Here, as shown in Figures 4 and 6, the first through hole 313 has a hole main body portion 71, a first recess 72 and a second recess 73.

The drum bearing portion 62 and the flap 63 are inserted into the hole main body portion 71. The hole main body portion 71 has an inner peripheral surface 710 that faces the outer peripheral surface of the drum bearing portion 62 and the outer peripheral surface of the flap 63. The inner peripheral surface 710 has a first flat surface 711 and a second flat surface 712 that are planar. The remaining part of the inner peripheral surface 710 is a part of the circumferential direction of the cylindrical shape.

As shown in Figures 4 and 6, the first recess 72 is recessed from the hole main body 71 toward the radially outward side of the photoconductor drum 40. The first rib 64 is inserted into the first recess 72. The second recess 73 is recessed from the hole main body 71 toward the radially outward side of the photoconductor drum 40. The second rib 65 is inserted into the second recess 73.

The cleaning roller bearing portion 66 extends cylindrically in the first direction from the support portion 61. The base end, which is one end of the cleaning roller bearing portion 66 in the first direction, is connected to the support portion 61. The tip end, which is the other end of the cleaning roller bearing portion 66 in the first direction, is located closer to the other end of the photosensitive drum 40 in the first direction than the base end of the cleaning roller bearing portion 66.

The cleaning roller bearing portion 66 is inserted into the second through hole 314 of the first fixed plate 312. Note that in one of the four bearing members 60, the cleaning roller bearing portion 66 is not inserted into the second through hole 314, but is fitted into a notch 317 provided in the first fixed plate 312.

The second gear 52 is attached to the cleaning roller bearing portion 66 at the other end side in the first direction of the photosensitive drum 40, closer to the first fixed plate 312. Specifically, the cleaning roller bearing portion 66 is inserted into the interior of the second gear 52. As a result, the cleaning roller 50 including the second gear 52 is rotatably supported by the cleaning roller bearing portion 66.

The hook 67 extends in a flat plate shape in the first direction from the support portion 61. The base end, which is one end of the hook 67 in the first direction, is connected to the support portion 61. The tip end, which is the other end of the hook 67 in the first direction, is located closer to the other end of the photoconductor drum 40 in the first direction than the base end of the hook 67. The hook 67 is inserted into the third through hole 315 of the first fixing plate 312. The hook 67 is positioned along the edge 316 of the third through hole 315.

<2-2. Positioning of the bearing member relative to the first fixed plate>
Next, the positioning of the bearing member 60 relative to the first fixed plate 312 will be described.

4 and 6, the first recess 72 is recessed from the hole main body 71 toward the outside in the radial direction of the photosensitive drum 40. The first rib 64 is inserted into the first recess 72. The tip of the first rib tip portion 642 of the first rib 64 faces the inner peripheral surface of the first recess 72 in the second direction and contacts the inner peripheral surface of the first recess 72. That is, the first rib 64 faces the inner peripheral surface of the first through hole 313 in the second direction and contacts the inner peripheral surface of the first through hole 313. As a result, the first rib 64 biases the bearing member 60 in one direction in the second direction against the first fixing plate 312 of the drum frame 30. As a result, the bearing member 60 can be positioned relative to the first through hole 313 of the drum frame 30.

The first rib 64 has elasticity. Therefore, even if the tip of the first rib tip portion 642 is designed to reliably contact the inner circumferential surface of the first recess 72, the first rib 64 can be accommodated in the first recess 72. Therefore, even if there is a design error or a difference in the expansion coefficient between the members, the biasing force of the first rib 64 can be secured. In this embodiment, specifically, the first rib 64 elastically deforms so that the first rib tip portion 642 moves in one direction in the second direction relative to the base end of the first rib base end portion 641. When the bearing member 60 is attached to the first fixing plate 312, the first rib tip portion 642 of the first rib 64 contacts the inner circumferential surface of the first recess 72 in a state where it is elastically deformed in one direction in the second direction from its natural state. As a result, a restoring force that causes the first rib 64 to return to its natural state acts on the inner circumferential surface of the first recess 72. The first rib 64 receives a reaction force of this restoring force from the inner circumferential surface of the first recess 72, and the reaction force urges the bearing member 60 in one direction in the second direction against the first fixed plate 312 of the drum frame 30.

The first rib 64 may be accommodated in the first recess 72 by elastic deformation, but may also be plastically deformed. In this case, when the first rib 64 is pressed into the first recess 72, the tip of the first rib tip portion 642 comes into contact with the inner peripheral surface of the first recess 72, undergoes plastic deformation, and is crushed.

The first rib 64 is composed of two parts: a first rib base end 641 that extends from the outer surface of the drum bearing portion 62 in the radial direction of the photosensitive drum 40, and a first rib tip end 642 that extends in the second direction. As a result, no matter where the first rib 64 extends from on the outer surface of the drum bearing portion 62, the first rib tip end 642 comes into contact with the inner surface of the first through hole 313 in the second direction, and the bearing member 60 is biased in the second direction. In other words, the first rib 64 is composed of two parts, the first rib base end 641 and the first rib tip end 642, which allows for greater design freedom.

The second recess 73 is recessed from the hole main body 71 toward the outside in the radial direction of the photosensitive drum 40. The second rib 65 is inserted into the second recess 73. The tip of the second rib tip portion 652 of the second rib 65 faces the inner peripheral surface of the second recess 73 in the second direction and contacts the inner peripheral surface of the second recess 73. That is, the second rib 65 faces the inner peripheral surface of the first through hole 313 in the second direction and contacts the inner peripheral surface of the first through hole 313. As a result, the second rib 65 biases the bearing member 60 in one direction in the second direction against the first fixed plate 312 of the drum frame 30. As a result, the bearing member 60 can be positioned more accurately with respect to the first through hole 313 of the drum frame 30.

The second rib 65 has elasticity. Therefore, even if the tip of the second rib tip portion 652 is designed to reliably contact the inner circumferential surface of the second recess 73, the second rib 65 can be accommodated in the second recess 73. Therefore, even if there is a design error or a difference in the expansion coefficient between the members, the biasing force by the second rib 65 can be secured. In this embodiment, specifically, the second rib 65 is elastically deformed so that the second rib tip portion 652 moves in one direction in the second direction relative to the base end of the second rib base end portion 651. When the bearing member 60 is attached to the first fixing plate 312, the second rib tip portion 652 of the second rib 65 contacts the inner circumferential surface of the second recess 73 in a state where it is elastically deformed in one direction in the second direction from its natural state. As a result, a restoring force that causes the second rib 65 to return to its natural state acts on the inner circumferential surface of the second recess 73. The second rib 65 receives a reaction force from the inner circumferential surface of the second recess 73, and the reaction force urges the bearing member 60 in one direction in the second direction against the first fixed plate 312 of the drum frame 30.

The second rib 65 may be accommodated in the second recess 73 by elastic deformation, but may also be plastically deformed. In this case, when the second rib 65 is pressed into the second recess 73, the tip of the second rib tip portion 652 comes into contact with the inner peripheral surface of the second recess 73, undergoes plastic deformation, and is crushed.

The second rib 65 is composed of two parts: a second rib base end 651 extending from the outer surface of the drum bearing portion 62 in the radial direction of the photosensitive drum 40, and a second rib tip end 652 extending in the second direction. As a result, no matter where the second rib 65 extends from on the outer surface of the drum bearing portion 62, the second rib tip end 652 comes into contact with the inner surface of the first through hole 313 in the second direction, and the bearing member 60 is biased in the second direction. In other words, the second rib 65 is composed of two parts, the second rib base end 651 and the second rib tip end 652, which allows for greater design freedom.

The first through hole 313 has a first recess 72 and a second recess 73 protruding from the hole body 71. The first rib 64 is located in the first recess 72. As a result, the tip of the first rib tip 642 of the first rib 64 faces the inner circumferential surface of the first recess 72 in the second direction and contacts it. The second rib 65 is located in the second recess 73. As a result, the tip of the second rib tip 652 of the second rib 65 faces the inner circumferential surface of the second recess 73 in the second direction and contacts it. By providing the first recess 72 and the second recess 73, it is easy to design the inner circumferential surface of the first through hole 313 to face the first rib 64 and the second rib 65 in the second direction. In other words, by providing the first recess 72 and the second recess 73, the design freedom for positioning the first fixing plate 312 and the bearing member 60 can be increased.

As shown in FIG. 6, in the circumferential direction of the photosensitive drum 40, the first rib 64 and the second rib 65 are positioned with the flap 63 in between. That is, the flap 63 is positioned between the first rib 64 and the second rib 65 in a third direction that intersects with the first direction and the second direction. In this embodiment, the third direction is perpendicular to the first direction and the second direction.

As a result, the first rib 64 and the second rib 65 position the bearing member 60 in the second direction relative to the first fixed plate 312 of the drum frame 30 on both sides of the flap 63, which positions the photosensitive drum 40 and the bearing member 60 in the second direction, perpendicular to the second direction. This makes it possible to more accurately position the photosensitive drum 40 in the second direction relative to the drum frame 30 via the bearing member 60.

In addition, in this embodiment, the first rib 64 and the second rib 65 are positioned 180° apart in the circumferential direction of the photosensitive drum 40. This allows the distance in the third direction between the first rib tip 642 of the first rib 64 and the second rib tip 652 of the second rib 65, which are used for positioning, to be increased. This makes it less likely that the bearing member 60 will tilt or shift in the second direction relative to the first fixed plate 312 of the drum frame 30, and provides stability. This allows the bearing member 60 to be more accurately positioned in the second direction relative to the drum frame 30.

As shown in FIG. 6, the first plane 711 and the second plane 712 are located on one side of the second direction relative to the first recess 72 and the second recess 73. Here, the normal vector direction of the first plane 711 is referred to as the fourth direction, and the normal vector direction of the second plane 712 is referred to as the fifth direction. Both the fourth direction and the fifth direction intersect with the first direction and also intersect with the second direction. The first direction is preferably perpendicular to the fourth direction and the fifth direction. Furthermore, the fourth direction and the fifth direction intersect with each other, and are preferably perpendicular to each other.

When the bearing member 60 is biased in the second direction relative to the first fixed plate 312 by the first rib 64 and the second rib 65, the outer peripheral surface of the drum bearing portion 62 comes into contact with the first flat surface 711 and the second flat surface 712. This allows the drum bearing portion 62 to be accurately positioned in the fourth and fifth directions relative to the first fixed plate 312. In particular, positioning accuracy can be improved compared to when the inner peripheral surface 710 of the hole main body portion 71 is a cylindrical surface (curved surface) around the entire circumference.

<2-3. Positioning of the photosensitive drum relative to the bearing member>
Next, the positioning of the photosensitive drum 40 relative to the bearing member 60 will be described.

As described above, the bearing insertion portion 423 of the first flange member 42 of the photosensitive drum 40 is inserted inside the drum bearing portion 62 and the flap 63. The flap 63 has elasticity. This allows the other end of the flap 63 in the first direction to swing in the second direction. In other words, the tip of the flap 64 can swing in the second direction. It has a pressing rib 631 that protrudes toward the radial inside of the photosensitive drum 40. This allows the pressing rib 631 to come into contact with the outer peripheral surface of the bearing insertion portion 423 and urge the bearing insertion portion 423 in one direction in the second direction. In other words, the flap 63 comes into contact with one end of the photosensitive drum 40 in the first direction and urges the photosensitive drum 40 in one direction in the second direction.

In order to absorb manufacturing errors and differences in the thermal expansion coefficients between the components, the diameters of the inner peripheral surfaces of the drum bearing portion 62 and the flap 63 are designed so that if the flap 63 does not have the pressing rib 631, a small gap will be created between the inner peripheral surfaces of the drum bearing portion 62 and the flap 63 and the outer peripheral surface of the bearing insertion portion 423. For this reason, by providing the pressing rib 631 at the tip of the flap 63, it is brought into contact with the outer surface of the photosensitive drum 40, and the photosensitive drum 40 is biased in one direction in the second direction toward the drum bearing portion 62. This allows the photosensitive drum 40 to be positioned in the second direction relative to the drum bearing portion 62.

In order to absorb manufacturing errors and differences in the thermal expansion coefficients between components, it is preferable that one end of the flap 63 in the first direction can deform more than the other end of the flap 63 in the first direction. In other words, it is preferable that the tip end of the flap 63 can deform more than the base end of the flap 63. In other words, it is preferable to improve the elasticity of the flap 63. In order to increase the amount of deformation of the flap 63 without changing the properties such as rigidity of the other parts of the bearing member 60, it is possible to increase the length of the flap 63 in the first direction.

Here, as shown in FIG. 7, the outer surface of the first fixing plate 312 of the drum frame 30 that is located around the first through hole 313 and extends in a direction intersecting the first direction is referred to as the plane 300.

On the other hand, as shown in Figures 5 and 7, the support portion 61 of the bearing member 60 has a first support surface 611 and a second support surface 612 that face the plane 300 in the first direction. The first support surface 611 is located closer to the other end of the photosensitive drum 40 in the first direction than the second support surface 612. Therefore, when the bearing member 60 is attached to the first fixed plate 312 and the first support surface 611 comes into contact with the plane 300, the second support surface 612 and the plane 300 face each other with a gap in the first direction.

The base end of the flap 63 is the end farthest in the first direction from the other end of the photosensitive drum 40 in the first direction. The base end of the flap 63 is connected to the second support surface 612. The plane 300 of the drum frame 30 is located between the other end of the photosensitive drum 40 in the first direction and the base end of the flap 63 in the first direction. In other words, the base end of the flap 63 is located farther from the other end of the photosensitive drum 40 in the first direction than the plane 300. In this way, the base end of the flap 63 is located outside the first fixing plate 312, so that the length of the flap 63 in the first direction can be increased. Therefore, the amount of deformation of the flap 63 can be increased.

In this way, the drum bearing portion 62, the flap 63, the first rib 64, the second rib 65, the cleaning roller bearing portion 66, and the hook 67 of the bearing member 60 are inserted into the first through hole 313, the second through hole 314, or the third through hole 315 of the first fixed plate 312. This positions and fixes the bearing member 60 relative to the first fixed plate 312. The bearing member 60 also rotatably supports one end of the photosensitive drum 40 in the first direction, and positions the photosensitive drum 40 relative to the bearing member 60. The bearing member 60 rotatably supports one end of the cleaning roller 50 in the first direction.

3. Modifications
Although one embodiment has been described above, the present disclosure is not limited to the above embodiment.

In the above embodiment, the drum unit 1 had four photosensitive drums 40. However, the number of photosensitive drums 40 that the drum unit 1 has may be one to three, or may be five or more.

The detailed shape of the drum unit may differ from the shapes shown in the drawings of this application. The elements appearing in the above embodiments and variations may be combined as appropriate to the extent that no contradictions arise.

1 drum unit 30 drum frame 31 first frame 40 photosensitive drum 41 drum body 42 first flange member 43 first gear 50 cleaning roller 60 bearing member 61 support portion 62 drum bearing portion 63 flap 64 first rib 65 second rib 66 cleaning roller bearing portion 71 hole body portion 72 first recess 73 second recess 91 first shaft 100 image forming apparatus 300 plane 312 first fixing plate 313 first through hole 314 second through hole 315 third through hole 423 bearing insertion portion 610 bearing through hole 641 first rib base end portion 642 first rib tip portion 651 second rib base end portion 652 second rib tip portion 710 inner circumferential surface 711 first plane 712 second plane

Claims (18)

a photoconductor drum rotatable about a first axis extending in a first direction;
a bearing member attached to one end of the photosensitive drum in the first direction;
a drum frame having a through hole penetrating in the first direction and into which the bearing member is inserted;
Equipped with
The bearing member is
a drum bearing portion covering a part of an outer circumferential surface of the photosensitive drum;
a flap positioned at an interval from the drum bearing portion in the circumferential direction of the photosensitive drum, covering another part of the outer circumferential surface of the photosensitive drum, the flap contacting the one end of the photosensitive drum in a second direction which is a radial direction of the photosensitive drum, and biasing the photosensitive drum in one direction in the second direction toward the drum bearing portion;
a first rib protruding from an outer circumferential surface of the drum bearing portion toward an outer side in the radial direction and biasing the bearing member against the drum frame;
A drum unit comprising: The drum unit of claim 1, characterized in that the first rib faces the inner circumferential surface of the through hole in the second direction and contacts the inner circumferential surface of the through hole. The first rib is
a base end portion extending radially outward from the outer circumferential surface of the drum bearing portion;
a tip portion extending in the second direction from a tip of the base portion, the tip portion facing an inner circumferential surface of the through hole in the second direction and in contact with the inner circumferential surface of the through hole;
3. The drum unit according to claim 2, further comprising: The drum unit according to claim 3, characterized in that the tip portion extends from the base portion in the other direction in the second direction, and the other end portion in the second direction contacts the inner circumferential surface of the through hole. The drum unit according to claim 2, characterized in that the first rib has elasticity. The through hole is
a hole main body portion having an inner peripheral surface facing an outer peripheral surface of the drum bearing portion and an outer peripheral surface of the flap;
a recess recessed from the hole body portion toward the radially outward side;
having
The drum unit according to claim 3 , wherein the first rib is located within the recess. an inner circumferential surface of the through hole includes a first plane and a second plane extending in different directions from each other,
2. The drum unit according to claim 1, wherein the first plane and the second plane each face an outer circumferential surface of the drum bearing portion and are in contact with the outer circumferential surface of the drum bearing portion. the flap has one end farthest in the first direction from the other end of the photosensitive drum in the first direction,
the drum bearing portion has one end farthest from the other end of the photosensitive drum in the first direction,
2 . The drum unit according to claim 1 , wherein the one end of the drum bearing portion is located between the other end of the photosensitive drum and the one end of the flap in the first direction. the flap has one end farthest in the first direction from the other end of the photosensitive drum in the first direction,
The drum frame has a plane located around the through hole and extending in a direction intersecting the first direction,
2 . The drum unit according to claim 1 , wherein the flat surface of the drum frame is located between the other end of the photosensitive drum and the one end of the flap in the first direction. The bearing member is
2. The drum unit according to claim 1, further comprising a second rib protruding radially outward from an outer circumferential surface of the drum bearing portion, the second rib working together with the first rib to bias the bearing member against the drum frame. The drum unit of claim 10, characterized in that the flap is located between the first rib and the second rib in a third direction intersecting the first direction and the second direction. The drum unit according to claim 11, characterized in that the first rib and the second rib bias the bearing member in one direction in the second direction toward the drum frame. The drum unit according to claim 10, characterized in that the second rib faces the inner circumferential surface of the through hole in the second direction and contacts the inner circumferential surface of the through hole. The second rib is
a base end portion extending radially outward from the outer circumferential surface of the drum bearing portion;
a tip portion extending in the second direction from a tip of the base portion, the tip portion facing an inner circumferential surface of the through hole in the second direction and in contact with the inner circumferential surface of the through hole;
14. The drum unit according to claim 13, further comprising: The drum unit according to claim 14, characterized in that the tip portion extends from the base end portion in the other direction in the second direction, and the other end portion in the second direction contacts the inner circumferential surface of the through hole. The drum unit according to claim 13, characterized in that the second rib has elasticity. a cleaning roller extending along the first direction and in contact with an outer circumferential surface of the photosensitive drum;
The bearing member is
2. The drum unit according to claim 1, further comprising a cylindrical cleaning roller bearing portion supporting one end of the cleaning roller in the first direction. The drum unit according to any one of claims 1 to 17, characterized in that the first direction is perpendicular to the second direction.

Images