Drum unit

Abstract

To provide a technique that makes it possible to suppress resistive forces due to an electrode when a developing roller is separated from a photoreceptor drum.SOLUTION: A drum unit has a guide surface 731 and a drum electrode 78. The guide surface 731 guides a collar 23 of a developing cartridge in a process of the developing cartridge being mounted to a drum frame 70. The drum electrode 78 has a developing contact part 783. The developing contact part 783 comes into contact with the collar 23 of the developing cartridge in a state of the developing cartridge being mounted to the drum frame 70. The developing contact part 783 extends along the guide surface 731. Therefore, resistive forces due to the drum electrode 78 can be suppressed when the developing roller is separated from a photoreceptor drum 60.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present disclosure relates to a drum unit. [Background technology]

[0002] 2. Description of the Related Art Conventionally, electrophotographic image forming apparatuses such as laser printers, LED printers, etc. are known. A conventional image forming apparatus is described in, for example, Patent Document 1.

[0003] The image forming apparatus of Patent Document 1 includes a developing cartridge having a developing roller and a drum unit having a photosensitive drum. The developing cartridge is attached to the drum unit. The drum unit with the developing cartridge attached is then attached to the image forming apparatus. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-179132 A Summary of the Invention [Problem to be solved by the invention]

[0005] The drum unit has electrodes that relay the supply of voltage from the image forming device to the developing roller. However, when the developing cartridge is attached to the drum unit, the image forming device performs a separation operation to temporarily separate the developing roller from the photosensitive drum. If the electrodes are positioned or oriented in a way that hinders the movement of the developing cartridge, the electrodes will act as a resistance during this separation operation, making it difficult for the developing cartridge to move.

[0006] An object of the present disclosure is to provide a technique capable of suppressing the resistance force caused by the electrodes when separating the developing roller from the photosensitive drum. [Means for solving the problem]

[0007] The first disclosure is a drum unit comprising a photosensitive drum rotatable about a drum axis extending in a first direction, and a drum frame rotatably supporting the photosensitive drum, the drum frame being capable of mounting a developing cartridge having a developing roller, the developing roller having a conductive developing roller shaft extending in the first direction and a conductive collar mounted to one end of the developing roller shaft in the first direction, the drum frame having a guide surface extending in a second direction intersecting the first direction, the second direction being a direction in which the collar moves during the process of mounting the developing cartridge to the drum frame, the guide surface guiding the collar during the process of mounting the developing cartridge to the drum frame, and a drum electrode, the drum electrode having a developing contact portion that contacts the collar when the developing cartridge is mounted to the drum frame, the developing contact portion extending along the second direction.

[0008] The second disclosure is the drum unit of the first disclosure, characterized in that the second direction is the direction in which the photosensitive drum and the developing roller are aligned when the developing cartridge is attached to the drum frame.

[0009] A third disclosure is the drum unit of the second disclosure, characterized in that it further includes a pressing member that presses the developing roller in the second direction toward the photosensitive drum when the developing cartridge is attached to the drum frame.

[0010] A fourth disclosure is a drum unit according to any one of the first to third disclosures, characterized in that the drum frame has a guide hole into which the collar is inserted when the developing cartridge is attached to the drum frame, the guide hole including the guide surface, the guide surface having an opening extending in the second direction, and the developing contact portion protruding from the opening into the guide hole.

[0011] A fifth disclosure is the drum unit according to any one of the first to third disclosures, wherein the drum electrode is a spring that is expandable and contractable in a direction intersecting the second direction.

[0012] A sixth disclosure is the drum unit of the fifth disclosure, characterized in that the drum electrode has a coil portion in which a metal wire is wound in a spiral shape, a first arm portion extending radially outward from one end of the coil portion, the first arm portion contacting a main body electrode of the image forming device when the drum unit is attached to a main body frame of the image forming device, and a second arm portion extending radially outward from the other end of the coil portion, the second arm portion including the developing contact portion.

[0013] A seventh disclosure is the drum unit of the sixth disclosure, characterized in that the second arm portion further includes a guide contact portion with which the collar comes into contact when the developing cartridge is mounted on the drum frame.

[0014] The eighth disclosure is a drum unit of the seventh disclosure, characterized in that, during the process of mounting the developing cartridge to the drum frame, the collar contacts the guide contact portion and then contacts the developing contact portion.

[0015] A ninth disclosure is a drum unit of the eighth disclosure, characterized in that the guide contact portion is inclined with respect to the second direction so as to move away from the guide surface as it moves toward the direction in which the color moves during the process of installing the developing cartridge into the drum frame, and the developing contact portion is inclined with respect to the second direction so as to move closer to the guide surface as it moves toward the direction in which the color moves during the process of installing the developing cartridge into the drum frame.

[0016] A tenth disclosure is a drum unit according to the ninth disclosure, characterized in that, when the developing cartridge is attached to the drum frame, the developing roller is movable between a contact position in contact with the photosensitive drum and a spaced position away from the photosensitive drum in the second direction, and the collar contacts the developing contact portion regardless of whether the developing roller is positioned at the contact position or the spaced position.

[0017] An eleventh disclosure is a drum unit according to any one of the first to third disclosures, characterized in that when the developing cartridge is attached to the drum frame, the developing roller is movable between a contact position in contact with the photosensitive drum and a spaced position away from the photosensitive drum in the second direction, and the collar contacts the developing contact portion regardless of whether the developing roller is positioned at the contact position or the spaced position.

[0018] The twelfth disclosure is a drum unit of the fifth disclosure, characterized in that the drum frame has a first guide surface which is the guide surface and a second guide surface opposite the first guide surface, and when the developing cartridge is attached to the drum frame, the collar is sandwiched between the second guide surface and the developing contact portion.

[0019] A thirteenth disclosure is a drum unit according to any one of the first to third disclosures, characterized in that the developing contact portion contacts the collar during the process of the developing cartridge being mounted to the drum frame, and continues to contact the collar until the mounting of the developing cartridge is complete. Effect of the Invention

[0020] According to the first to thirteenth disclosures, the developing contact portion of the drum electrode extends along the guide surface, which makes it possible to suppress the resistance force of the drum electrode when the developing roller is separated from the photosensitive drum. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram of an image forming apparatus. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] 2 is a cross-sectional view of the developing cartridge taken along a plane perpendicular to a first direction. FIG. [Diagram 5] FIG. [Figure 6] FIG. 4 is a perspective view of a first guide frame as viewed from the inner surface side. [Figure 7] FIG. 4 is a perspective view of a first guide frame as viewed from the outer surface side. [Figure 8] FIG. [Figure 9] 11A and 11B are diagrams showing the movement of the first color when the developing cartridge is mounted on the drum frame. [Figure 10] 11A and 11B are diagrams showing the movement of the first color when the developing cartridge is mounted on the drum frame. [Figure 11] 11A and 11B are diagrams showing the movement of the first color when the developing cartridge is mounted on the drum frame. [Figure 12] 13A and 13B are diagrams illustrating the movement of a first collar during a separating operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0023] In the following, the direction in which the drum axis of the photosensitive drum extends is referred to as the "first direction." Furthermore, the direction in which the photosensitive drum and the developing roller are aligned when the developing cartridge is mounted in the drum frame is referred to as the "second direction." Furthermore, the direction in which multiple photosensitive drums are aligned in the drum unit is referred to as the "third direction."

[0024] The first direction and the second direction intersect with each other. Preferably, the first direction and the second direction are perpendicular to each other. The second direction and the third direction intersect with each other. The third direction and the first direction intersect with each other. Preferably, the third direction and the first direction are perpendicular to each other.

[0025] <1. Configuration of image forming device> FIG. 1 is a schematic diagram of an image forming apparatus 100. This image forming apparatus 100 is an electrophotographic printer. Specifically, the image forming apparatus 100 is a laser printer or an LED printer. As shown in FIG. 1, the image forming apparatus 100 includes a main body frame 101, a drum unit 2, and four developing cartridges 1. The four developing cartridges 1 can be attached to the drum unit 2. Furthermore, the drum unit 2 with the four developing cartridges 1 attached can be attached to the main body frame 101.

[0026] As an example, the four developer cartridges 1 are arranged in the second direction in the following order: developer cartridge 1 containing yellow toner, developer cartridge 1 containing magenta toner, developer cartridge 1 containing cyan toner, and developer cartridge 1 containing black toner. The image forming device 100 prints an image on the surface of a printing paper using toner supplied from the developer cartridges 1.

[0027] <2. Structure of the developing cartridge> Figures 2 and 3 are perspective views of the developing cartridge 1. Figure 4 is a cross-sectional view of the developing cartridge 1 cut along a plane perpendicular to the first direction. As shown in Figures 2 to 4, the developing cartridge 1 includes a housing 10, a developing roller 20, a supply roller 30, a gear portion 40, and a spacing member 50.

[0028] <2-1. Cabinet> The housing 10 is a container capable of storing toner. The housing 10 has a first outer surface 11 and a second outer surface 12. The first outer surface 11 is located at one end of the housing 10 in the first direction. The second outer surface 12 is located at the other end of the housing 10 in the first direction. The first outer surface 11 and the second outer surface 12 are separated from each other in the first direction.

[0029] A storage chamber 13 is provided inside the housing 10. Toner is stored in the storage chamber 13. As shown in FIG. 4, the housing 10 has a supply port 14. The supply port 14 is located at one end of the housing 10 in the second direction. The external space of the housing 10 and the storage chamber 13 communicate with each other via the supply port 14. As shown in FIGS. 3 and 4, the housing 10 has a handle 15. The handle 15 is located at the other end of the housing 10 in the second direction.

[0030] The developing cartridge 1 also has a bearing member 18. The bearing member 18 is located on the first outer surface 11 of the housing 10. The bearing member 18 is attached to the first outer surface 11 of the housing 10 by a screw. The bearing member 18 is a conductive member. Specifically, the bearing member 18 is formed from a conductive resin.

[0031] <2-2. Developing roller> The developing roller 20 is a roller that can rotate about a development axis that extends in the first direction. The developing roller 20 is located at the supply port 14 of the housing 10. That is, the developing roller 20 is located at one end of the housing 10 in the second direction.

[0032] The developing roller 20 has a developing roller body 21 and a developing roller shaft 22. The developing roller body 21 is a cylindrical member extending in a first direction. The developing roller body 21 is made of, for example, elastic rubber. The developing roller shaft 22 is a cylindrical member extending in the first direction through the developing roller body 21. The developing roller body 21 is fixed to the developing roller shaft 22. The developing roller shaft 22 is a conductive member. Specifically, the developing roller shaft 22 is made of metal or conductive resin.

[0033] One end of the developing roller shaft 22 in the first direction is inserted into a circular first bearing hole provided in the bearing member 18. As a result, one end of the developing roller shaft 22 in the first direction is rotatably supported with respect to the housing 10. In addition, the developing roller shaft 22 and the bearing member 18 are electrically connected by contacting each other. The other end of the developing roller shaft 22 in the first direction is attached to a developing roller gear included in the gear unit 40. When the developing roller gear rotates, the developing roller shaft 22 and the developing roller main body 21 rotate about the development axis. The toner in the housing 10 is supported on the outer circumferential surface of the developing roller main body 21.

[0034] 2 and 3, the developing roller 20 has a first collar 23 and a second collar 24. The first collar 23 is attached to one end of the developing roller shaft 22 in the first direction. The second collar 24 is attached to the other end of the developing roller shaft 22 in the first direction. The first collar 23 and the second collar 24 have cylindrical outer circumferential surfaces centered on the development axis. The first collar 23 and the second collar 24 may be rotatable about the development axis relative to the developing roller shaft 22.

[0035] The first collar 23 is an example of a "collar." The first collar 23 is a conductive member. The first collar 23 is made of, for example, a conductive resin. The first collar 23 is located outside the bearing member 18 in the first direction.

[0036] As shown in FIG. 4, the developing cartridge 1 has a blade 25. The blade 25 is located at the supply port 14. The blade 25 is an elastic plate. One end of the blade 25 is attached to the housing 10. The other end of the blade 25 contacts the outer circumferential surface of the developing roller 20. More specifically, the other end of the blade 25 contacts the toner carried on the outer circumferential surface of the developing roller 20. The blade 25 extends in the first direction along the outer circumferential surface of the developing roller 20. The blade 25 shapes the toner carried on the outer circumferential surface of the developing roller 20 to a predetermined thickness.

[0037] <2-3. Supply roller> The supply roller 30 is a roller that can rotate about a supply axis that extends in the first direction. The supply roller 30 is located inside the housing 10. The supply roller 30 has a supply roller main body 31 and a supply roller shaft 32. The supply roller main body 31 is a cylindrical member that extends in the first direction. The supply roller main body 31 is made of, for example, elastic rubber. The outer circumferential surface of the supply roller main body 31 contacts the outer circumferential surface of the developing roller main body 21. The supply roller shaft 32 is a cylindrical member that penetrates the supply roller main body 31 and extends in the first direction. The supply roller main body 31 is fixed to the supply roller shaft 32. The supply roller shaft 32 is made of metal or conductive resin.

[0038] One end of the supply roller shaft 32 in the first direction is inserted into a circular second bearing hole provided in the bearing member 18. As a result, one end of the supply roller shaft 32 in the first direction is rotatably supported with respect to the housing 10. In addition, the supply roller shaft 32 and the bearing member 18 are electrically connected by contacting each other. The other end of the supply roller shaft 32 in the first direction is attached to a supply roller gear included in the gear unit 40. When the supply roller gear rotates, the supply roller shaft 32 and the supply roller main body 31 rotate about the supply axis. The toner in the housing 10 is supplied to the development roller 20 via the supply roller 30.

[0039] <2-4. Gear section> The gear portion 40 is located on the second outer surface 12 of the housing 10. The gear portion 40 has a gear cover 41, a coupling 42, and a plurality of gears. The gear cover 41 is attached to the second outer surface 12 of the housing 10. Specifically, the gear cover 41 is fixed to the second outer surface 12 of the housing 10 by screws.

[0040] The multiple gears include the above-mentioned developing roller gear and supply roller gear. The coupling 42 and the multiple gears are each rotatable about an axis extending in the first direction. At least some of the multiple gears are located between the first outer surface 11 of the housing 10 and the gear cover 41 in the first direction. That is, at least some of the multiple gears are covered by the gear cover 41.

[0041] The coupling 42 is exposed from the gear cover 41. When the drum unit 2 in which the developing cartridge 1 is mounted is mounted to the image forming apparatus 100, the drive shaft of the image forming apparatus 100 is connected to the coupling 42. Then, the rotation of the drive shaft is transmitted to multiple gears via the coupling 42.

[0042] <2-5. Spacing members> When the drum unit 2 in which the four developer cartridges 1 are mounted is installed in the image forming apparatus 100, the image forming apparatus 100 can perform a separation operation for each developer cartridge 1. The separation operation is an operation for moving the developer roller 20 from a contact position in contact with the photosensitive drum 60 to a separation position away from the photosensitive drum 60, which will be described later.

[0043] The spacing member 50 is a component for switching the developing roller 20 between the contact position and the separated position described above. That is, the developing cartridge 1 is switched by the spacing member 50 from a state in which the developing roller 20 is in the contact position to a state in which the developing roller 20 is in the separated position.

[0044] 2, the spacing member 50 has a first cam 51, a second cam 52, and a spacing shaft 53. The spacing member 50 is made of, for example, resin. Specifically, the first cam 51, the second cam 52, and the spacing shaft 53 are integrally molded from resin. However, the first cam 51, the second cam 52, and the spacing shaft 53 may be separate parts. In that case, only the first cam 51 and the second cam 52 may be made of resin, and the spacing shaft 53 may be made of metal.

[0045] As shown in FIG. 2, the developing cartridge 1 has a first through hole 191, a second through hole 192, and a guide groove 193. The guide groove 193 is located on the outer surface of the housing 10. The first through hole 191 is located at one end of the developing cartridge 1 in the first direction. The first through hole 191 is a hole extending in the first direction. The second through hole 192 is located at the other end of the developing cartridge 1 in the first direction. The second through hole 192 is a hole extending in the first direction. The guide groove 193 is located between the first through hole 191 and the second through hole 192 in the first direction. The guide groove 193 extends in the first direction on the outer surface of the housing 10.

[0046] The spaced shaft 53 is disposed in the guide groove 193. The spaced shaft 53 extends in a first direction along the guide groove 193. One end of the spaced shaft 53 in the first direction is inserted into the first through hole 191. As a result, the one end of the spaced shaft 53 in the first direction is supported by the housing 10. The other end of the spaced shaft 53 in the first direction is inserted into the second through hole 192. As a result, the other end of the spaced shaft 53 in the first direction is supported by the housing 10.

[0047] The first cam 51 is located at one end of the spacing member 50 in the first direction. The first cam 51 is located on the first outer surface 11 of the housing 10. The first cam 51 has a first inclined surface 511. The first inclined surface 511 is a part of a circumferential surface centered on the spacing shaft 53. The first inclined surface 511 is inclined with respect to the first direction. More specifically, the first inclined surface 511 is inclined so as to approach the developing roller 20 in the second direction as it approaches the other end of the spacing member 50 in the first direction.

[0048] The second cam 52 is located at the other end of the spacing member 50 in the first direction. The second cam 52 is located on the second outer surface 12 of the housing 10. The second cam 52 has a second inclined surface 521. The second inclined surface 521 is a part of a circumferential surface centered on the spacing shaft 53. The second inclined surface 521 is inclined with respect to the first direction. More specifically, the second inclined surface 521 is inclined so as to approach the developing roller 20 in the second direction as it approaches the other end of the spacing member 50 in the first direction.

[0049] The spacing member 50 is movable in the first direction between a first position and a second position relative to the housing 10 and the developing roller 20. The second position is a position closer to one end of the spacing member 50 than the first position. Therefore, movement from the first position to the second position is movement in a direction from the second cam 52 toward the first cam 51.

[0050] The developing cartridge 1 also has a spring that biases the spacing member 50. The spring is expandable and contractible in a first direction. The spring is disposed between the second outer surface 12 of the housing 10 and the second cam 52 in a state in which it is contracted in the first direction from its natural length. Therefore, the elastic force of the spring biases the spacing member 50 from the second position toward the first position. Therefore, the spacing member 50 is disposed in the first position when it is not subjected to an external force.

[0051] <3. Drum unit configuration> 5 is a perspective view of the drum unit 2. As shown in FIG. 5, the drum unit 2 includes four photoconductor drums 60 and a drum frame 70.

[0052] <3-1. Photoconductor drum> The photosensitive drum 60 is a drum that is rotatable about a drum axis D that extends in the first direction. The photosensitive drum 60 is located at one end of the drum frame 70 in the second direction. The photosensitive drum 60 has a cylindrical outer circumferential surface centered on the drum axis D. The outer circumferential surface of the photosensitive drum 60 is covered with a photosensitive material.

[0053] The four photoconductor drums 60 are arranged in the third direction. As an example, the four photoconductor drums 60 are arranged in the third direction in the following order: photoconductor drum 60 corresponding to yellow toner, photoconductor drum 60 corresponding to magenta toner, photoconductor drum 60 corresponding to cyan toner, and photoconductor drum 60 corresponding to black toner.

[0054] The photoconductor drum 60 corresponding to the yellow toner and the photoconductor drum 60 corresponding to the magenta toner are arranged at an interval in the third direction. The photoconductor drum 60 corresponding to the magenta toner and the photoconductor drum 60 corresponding to the cyan toner are arranged at an interval in the third direction. The photoconductor drum 60 corresponding to the cyan toner and the photoconductor drum 60 corresponding to the black toner are arranged at an interval in the third direction.

[0055] <3-2. Drum frame> The drum frame 70 supports the four photosensitive drums 60 rotatably about a drum axis D. The drum frame 70 has a first side frame 71, a first metal plate (not shown), a first guide frame 73, a second side frame 74, a second metal plate (not shown), a second guide frame 76, and a connection frame 77.

[0056] The first side frame 71, the first metal plate, and the first guide frame 73 are located at one end of the drum frame 70 in the first direction. The first side frame 71 and the first guide frame 73 are made of resin. The first metal plate is made of a metal having higher rigidity than the first side frame 71 and the first guide frame 73.

[0057] The first metal plate extends in the second and third directions. The first metal plate has an inner surface and an outer surface. When the developer cartridge 1 is attached to the drum unit 2, the inner surface of the first metal plate faces the first outer surface 11 of the developer cartridge 1 in the first direction. The outer surface of the first metal plate is the surface opposite to the inner surface of the first metal plate. The first side frame 71 is fixed to the outer surface of the first metal plate. The first guide frame 73 is fixed to the inner surface of the first metal plate.

[0058] The second side frame 74, the second metal plate, and the second guide frame 76 are located at the other end of the drum frame 70 in the first direction. The second side frame 74 and the second guide frame 76 are made of resin. The second metal plate is made of a metal having higher rigidity than the second side frame 74 and the second guide frame 76.

[0059] The second metal plate extends in the second and third directions. The second metal plate has an inner surface and an outer surface. When the developer cartridge 1 is attached to the drum unit 2, the inner surface of the second metal plate faces the second outer surface 12 of the developer cartridge 1 in the first direction. The outer surface of the second metal plate is the surface opposite to the inner surface of the second metal plate. The second side frame 74 is fixed to the outer surface of the second metal plate. The second guide frame 76 is fixed to the inner surface of the second metal plate.

[0060] The connection frame 77 connects the first guide frame 73 and the second guide frame 76 in the first direction.

[0061] The four developer cartridges 1 are mounted on the drum frame 70. When the developer cartridges 1 are mounted on the drum frame 70, the housing 10 is located between the first side frame 71 and the second side frame 74 in the first direction. The drum frame 70 also has a pressing member 79. When the developer cartridges 1 are mounted on the drum frame 70, the pressing member 79 presses the developer cartridge 1 in the second direction toward the photosensitive drum 60. This presses the developer roller 20 in the second direction toward the photosensitive drum 60. As a result, the developer roller 20 comes into contact with the photosensitive drum 60. More specifically, the outer peripheral surface of the developer roller 20 comes into contact with the outer peripheral surface of the photosensitive drum 60. This makes it possible to supply the toner carried on the outer peripheral surface of the developer roller 20 to the photosensitive drum 60.

[0062] <3-3. Guide holes> As shown in FIG. 5, the first guide frame 73 has a first guide hole 730. The first guide hole 730 is an example of a "guide hole." The first guide hole 730 is recessed toward the photosensitive drum 60 in the second direction in which the photosensitive drum 60 and the developing roller 20 are aligned. When the developing cartridge 1 is attached to the drum frame 70, the first collar 23 of the developing cartridge 1 is inserted into the first guide hole 730. This allows the developing cartridge 1 to be guided relative to the drum frame 70.

[0063] FIG. 6 is a perspective view of the first guide frame 73 as viewed from the inner surface side. As shown in FIG. 6, the first guide hole 730 has a first guide surface 731 and a second guide surface 732. The first guide surface 731 is an example of a "guide surface". The first guide surface 731 extends in the second direction. The second guide surface 732 faces the first guide surface 731 in a fourth direction intersecting the first direction and the second direction. The second guide surface 732 extends in the second direction.

[0064] In the process of mounting the developer cartridge 1 to the drum frame 70, the first collar 23 moves in the second direction along the first guide surface 731 and the second guide surface 732. That is, in the process of mounting the developer cartridge 1 to the drum frame 70, the first guide surface 731 and the second guide surface 732 guide the first collar 23 in the second direction.

[0065] The second guide frame 76 has a second guide hole (not shown) similar to the first guide hole 730. The second guide hole is recessed toward the photosensitive drum 60 in the second direction in which the photosensitive drum 60 and the developing roller 20 are aligned. When the developing cartridge 1 is attached to the drum frame 70, the second collar 24 of the developing cartridge 1 is inserted into the second guide hole. This allows the developing cartridge 1 to be guided relative to the drum frame 70.

[0066] <3-4. Drum electrodes> Fig. 7 is a perspective view of the first guide frame 73 as viewed from the outer surface side. As shown in Figs. 6 and 7, the drum frame 70 has a drum electrode 78. The drum electrode 78 is located at one end of the drum frame 70 in the first direction. More specifically, the drum electrode 78 is attached to the first guide frame 73. The drum electrode 78 is made of a conductive metal.

[0067] When the developer cartridge 1 is attached to the drum frame 70, the drum electrode 78 comes into contact with the first collar 23 of the developer cartridge 1. The image forming apparatus 100 also has a main body electrode. When the drum frame 70 in which the developer cartridge 1 is attached is attached to the main body frame 101 of the image forming apparatus 100, the drum electrode 78 comes into contact with the main body electrode. This allows the drum electrode 78 to relay the supply of voltage from the main body electrode to the first collar 23.

[0068] When the image forming apparatus 100 is in use, a voltage is supplied from the main body electrode to the developing roller shaft 22 via the drum electrode 78 and the first collar 23. Then, toner is carried on the outer circumferential surface of the developing roller 20 by electrostatic force generated by the voltage supplied to the developing roller shaft 22.

[0069] Furthermore, when the image forming apparatus 100 is in use, a voltage is supplied from the main body electrode to the supply roller shaft 32 via the drum electrode 78, the first collar 23, and the bearing member 18. Then, toner is carried on the outer circumferential surface of the supply roller 30 by electrostatic force generated by the voltage supplied to the supply roller shaft 32.

[0070] FIG. 8 is a perspective view of the drum electrode 78. The drum electrode 78 is a spring that can expand and contract in a fourth direction. The drum electrode 78 is formed of a metal wire. As shown in FIG. 8, the drum electrode 78 has a coil portion 780, a first arm portion 781, and a second arm portion 782. The coil portion 780 is a portion in which a metal wire is wound in a spiral shape. More specifically, the coil portion 780 is a portion in which a metal wire is wound in a spiral shape around an axis extending in the first direction.

[0071] The first arm 781 is a portion where a metal wire extends from one end of the coil portion 780 in the first direction toward the outside in the radial direction of the coil portion 780. As shown in FIG. 7, in a state where the drum electrode 78 is attached to the first guide frame 73, the first arm 781 extends in the fourth direction. At least a part of the first arm 781 is exposed on the outer surface of the drum frame 70. In a state where the drum unit 2 is attached to the main body frame 101 of the image forming apparatus 100, the first arm 781 comes into contact with the main body electrode. This electrically connects the main body electrode and the drum electrode 78.

[0072] The second arm portion 782 is a portion where the metal wire extends from the other end of the coil portion 780 in the first direction toward the radially outer side of the coil portion 780. As shown in FIG. 6, in a state where the drum electrode 78 is attached to the first guide frame 73, the second arm portion 782 extends in the second direction. The first guide surface 731 of the first guide frame 73 has an opening 733. The opening 733 is a slit-shaped hole extending in the second direction. The opening 733 penetrates the first guide surface 731 in the fourth direction. A portion of the second arm portion 782 protrudes from the opening 733 into the first guide hole 730.

[0073] The second arm portion 782 has a developer contact portion 783 and a guide contact portion 784. The developer contact portion 783 is located between the coil portion 780 and the guide contact portion 784. A portion of the developer contact portion 783 protrudes from the opening 733 into the first guide hole 730. A portion of the guide contact portion 784 also protrudes from the opening 733 into the first guide hole 730. The developer contact portion 783 and the guide contact portion 784 extend in the second direction along the first guide surface 731.

[0074] However, the developer contact portion 783 is slightly inclined with respect to the first guide surface 731. Specifically, the portion of the developer contact portion 783 protruding from the opening 733 is inclined with respect to the second direction so as to approach the first guide surface 731 as it moves toward the direction in which the first collar 23 moves during the process of mounting the developer cartridge 1 to the drum frame 70. In other words, the portion of the developer contact portion 783 protruding from the opening 733 is inclined with respect to the second direction so as to move away from the second guide surface 732 as it moves toward the direction in which the first collar 23 moves during the process of mounting the developer cartridge 1 to the drum frame 70.

[0075] Moreover, the guide contact portion 784 is slightly inclined with respect to the first guide surface 731. Specifically, the portion of the guide contact portion 784 protruding from the opening 733 is inclined with respect to the second direction so as to move away from the first guide surface 731 as it moves toward the direction in which the first collar 23 moves during the process of mounting the developer cartridge 1 to the drum frame 70. In other words, the portion of the guide contact portion 784 protruding from the opening 733 is inclined with respect to the second direction so as to move closer to the second guide surface 732 as it moves toward the direction in which the first collar 23 moves during the process of mounting the developer cartridge 1 to the drum frame 70.

[0076] 9 to 11 are views showing the movement of the first collar 23 when the developing cartridge 1 is mounted on the drum frame 70. Figures 9 to 11 show a cross section that includes the first guide hole 730 and is perpendicular to the first direction.

[0077] When the developer cartridge 1 is attached to the drum frame 70, first, as shown in Fig. 9, the first collar 23 of the developer cartridge 1 moves in the fourth direction toward the guide contact portion 784. Then, as shown in Fig. 10, the first collar 23 comes into contact with the guide contact portion 784. This stops the movement of the first collar 23 in the fourth direction.

[0078] Thereafter, the pressing member 79 presses the developer cartridge 1 in the second direction toward the photosensitive drum 60. This causes the first collar 23 to move along the guide contact portion 784. Specifically, the first collar 23 moves in the second direction toward the first guide hole 730. As a result, as shown in FIG. 11, the first collar 23 comes into contact with the developer contact portion 783. The developer contact portion 783 comes into contact with the first collar 23 during the process of mounting the developer cartridge 1 to the drum frame 70, and continues to be in contact with the first collar 23 until mounting of the developer cartridge 1 is complete.

[0079] The drum electrode 78 is expandable and contractable in the fourth direction. Specifically, the second arm portion 782 is movable in the fourth direction relative to the first arm portion 781. Therefore, the developer contact portion 783 is movable in the fourth direction relative to the first guide surface 731. Due to the elastic force of the drum electrode 78, which is a spring, the developer contact portion 783 presses the first collar 23 in the fourth direction toward the second guide surface 732. As a result, the developer contact portion 783 and the first collar 23 are stably contacted. Therefore, the developer contact portion 783 and the first collar 23 are stably electrically connected.

[0080] <4. Separation operation> When the image forming apparatus 100 performs a spacing operation while the drum unit 2, to which the four developing cartridges 1 are attached, is attached to the image forming apparatus 100, the image forming apparatus 100 presses the second cam 52 in a first direction toward the first cam 51. Then, a spring disposed between the second outer surface 12 of the housing 10 and the second cam 52 contracts, and the spacing member 50 moves from the first position to the second position relative to the housing 10.

[0081] In the process in which the spacing member 50 moves from the first position to the second position, the first inclined surface 511 of the first cam 51 moves in the first direction while contacting the drum frame 70. At this time, the first cam 51 moves in the second direction relative to the drum unit 2 due to the resistance force received from the drum frame 70. More specifically, the first cam 51 moves in a direction away from the photosensitive drum 60 relative to the drum unit 2 due to the resistance force received from the drum frame 70.

[0082] Similarly, in the process of the spacing member 50 moving from the first position to the second position, the second inclined surface 521 of the second cam 52 moves in the first direction while contacting the drum frame 70. At this time, the second cam 52 moves in the second direction relative to the drum unit 2 due to the resistance force received from the drum frame 70. More specifically, the second cam 52 moves in a direction away from the photosensitive drum 60 relative to the drum unit 2 due to the resistance force received from the drum frame 70.

[0083] As a result, the housing 10 and the developing roller 20 move together with the spacing member 50 in the second direction relative to the drum unit 2. More specifically, the housing 10 and the developing roller 20 move in a direction away from the photosensitive drum 60 relative to the drum unit 2. As a result, the developing roller 20 moves in the second direction from a contact position where it contacts the photosensitive drum 60 to a separated position away from the photosensitive drum 60 in the second direction.

[0084] FIG. 12 is a diagram showing the movement of the first collar 23 during the separation operation. FIG. 12 shows a cross section including the first guide hole 730 and perpendicular to the first direction. As shown in FIG. 12, during the separation operation, the first collar 23 moves in the second direction together with the developing roller 20 in a direction away from the photosensitive drum 60. However, the first collar 23 contacts the developing contact portion 783 of the drum electrode 78 whether the developing roller 20 is disposed at the contact position or at the separation position. That is, while the developing roller 20 moves from the contact position to the separation position, the first collar 23 maintains a state of contact with the developing contact portion 783 of the drum electrode 78.

[0085] 12, the developing contact portion 783 extends along the second direction. Therefore, when the first collar 23 moves in the second direction during the separation operation, the resistance force applied from the developing contact portion 783 to the first collar 23 is small. Therefore, the first collar 23 can move smoothly in the second direction relative to the developing contact portion 783 while maintaining a state of contact with the developing contact portion 783.

[0086] <5. Modifications> Although one embodiment has been described above, the present disclosure is not limited to the above embodiment.

[0087] In the above embodiment, the number of developer cartridges 1 that can be attached to the drum unit 2 is four. However, the number of developer cartridges 1 that can be attached to the drum unit 2 may be one to three, or may be five or more.

[0088] Furthermore, the elements appearing in the above-described embodiment and modified examples may be combined as appropriate or some may be deleted to the extent that no contradictions arise. [Explanation of symbols]

[0089] 1: Developing cartridge 2: Drum unit 10: Housing 20: Developing roller 30: Supply roller 40: Gear section 50: Spacer 60: Photoconductor drum 70: Drum frame 78: Drum electrode 79: Pressing member 100: Image forming apparatus 730: First guide hole 731: First guide surface 732: Second guide surface 733 :Aperture 780: Coil section 781 :1st arm 782:Second arm 783: Development contact part 784: Guide contact part

Claims

1. a photosensitive drum rotatable about a drum axis extending in a first direction; a drum frame that rotatably supports the photosensitive drum, and into which a developing cartridge having a developing roller can be attached; A drum unit comprising: The developing roller is a conductive developer roller shaft extending in the first direction; a conductive collar attached to one end of the developing roller shaft in the first direction; having The drum frame is a guide surface extending in a second direction intersecting the first direction, the guide surface being a direction in which the collar moves during a process in which the developer cartridge is mounted to the drum frame, the guide surface guiding the collar during a process in which the developer cartridge is mounted to the drum frame; A drum electrode; having The drum electrode is a developer contact portion that contacts the collar when the developer cartridge is attached to the drum frame, the developer contact portion extending along the second direction; A drum unit comprising:

2. 2. The drum unit according to claim 1, The drum unit according to claim 1, wherein the second direction is a direction in which the photosensitive drum and the developing roller are aligned when the developing cartridge is attached to the drum frame.

3. 3. The drum unit according to claim 2, a pressing member that presses the developing roller in the second direction toward the photosensitive drum when the developing cartridge is attached to the drum frame; The drum unit further comprises:

4. 4. The drum unit according to claim 1, The drum frame is a guide hole into which the collar is inserted when the developing cartridge is attached to the drum frame, the guide hole including the guide surface; having The guide surface has an opening extending in the second direction, The developing contact portion protrudes from the opening into the guide hole.

5. 4. The drum unit according to claim 1, The drum unit is characterized in that the drum electrode is a spring that is expandable and contractable in a direction intersecting the second direction.

6. 6. The drum unit according to claim 5, The drum electrode is A coil portion in which a metal wire is wound in a spiral shape; a first arm portion extending from one end of the coil portion toward an outer side in a radial direction of the coil portion, the first arm portion being in contact with a main body electrode of the image forming apparatus when the drum unit is attached to a main body frame of the image forming apparatus; a second arm portion extending from the other end of the coil portion toward an outer side in a radial direction of the coil portion, the second arm portion including the developing contact portion; A drum unit comprising:

7. 7. The drum unit according to claim 6, The second arm portion is a guide contact portion with which the collar comes into contact when the developing cartridge is mounted on the drum frame; The drum unit further comprises:

8. 8. The drum unit according to claim 7, a developing cartridge mounted on the drum frame, the collar contacting the guide contact portion and then contacting the developing cartridge contact portion, the developing cartridge being supported by the developing cartridge support member and the developing cartridge being supported by the developing cartridge support member and the developing cartridge being supported by the developing cartridge support member and the developing cartridge support member.

9. 9. The drum unit according to claim 8, the guide contact portion is inclined with respect to the second direction so as to move away from the guide surface as the guide contact portion moves in a direction in which the collar moves during a process in which the developing cartridge is mounted to the drum frame; the developer contact portion is inclined with respect to the second direction so as to approach the guide surface as the developer contact portion moves in a direction in which the collar moves during a process in which the developer cartridge is mounted on the drum frame.

10. 10. The drum unit according to claim 9, When the developing cartridge is mounted in the drum frame, the developing roller is movable between a contact position where the developing roller contacts the photosensitive drum and a spaced position where the developing roller is spaced from the photosensitive drum in the second direction, a developing roller that is disposed in either the contact position or the spaced position, the collar being in contact with the developing contact portion;

11. 4. The drum unit according to claim 1, When the developing cartridge is mounted in the drum frame, the developing roller is movable between a contact position where the developing roller contacts the photosensitive drum and a spaced position where the developing roller is spaced from the photosensitive drum in the second direction, a developing roller that is disposed in either the contact position or the spaced position, the collar being in contact with the developing contact portion;

12. 6. The drum unit according to claim 5, The drum frame is A first guide surface which is the guide surface; a second guide surface facing the first guide surface; having a developing cartridge mounted on the drum frame, the collar being sandwiched between the second guide surface and the developing cartridge contact portion;

13. 4. The drum unit according to claim 1, The developing contact portion contacts the collar during the process of mounting the developing cartridge to the drum frame, and continues to contact the collar until the mounting of the developing cartridge is completed.

Images