Drum unit and image forming apparatus

Abstract

To prevent variations in the flow rate of air flowing along a charging opening.SOLUTION: A drum unit 30 comprises: a first photoreceptor (photoconductor drum 32K); a first charging electrode (charging wire 331) extending in an axial direction of the first photoreceptor; a first charging frame (charging frame F5K) that holds the first charging electrode and has a first charging opening (charging opening F52); a first wall W1 that faces the first charging opening; a side frame (first side frame F1) that supports an end in an axial direction of the first charging frame; and a first film FL1. The side frame has a first vent hole (vent hole HK) that opens in the axial direction. The first film FL1 extends from one of the first charging frame and the first wall W1 to the other, and is located between a frame having the first wall W1 and the first charging frame. When air flows from the first vent hole toward the first charging frame, the air is guided by the first charging frame, the first wall W1, and the first film FL1 and flows in the axial direction.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to a drum unit and an image forming apparatus. [Background technology]

[0002] Conventionally, there is known an image forming apparatus that includes a main body housing, a drum unit that can be pulled out from the main body housing, and a developing cartridge that can be attached to and detached from the drum unit (see Patent Document 1). The drum unit includes a photosensitive drum, a charging wire that charges the photosensitive drum, and a charging frame that holds the charging wire.

[0003] The charging frame has a charging opening. The charging opening is located on the opposite side of the charging wire from the photosensitive drum. The charging opening extends in the direction in which the charging wire extends. The charging opening faces the developer cartridge.

[0004] Also known as an image forming device is a structure in which a vent hole is provided in the side frame of the drum unit (see Patent Document 2). In this structure, air taken into the drum unit through the vent hole flows along the charging opening, passes through the charging opening and around the charging wire toward the photosensitive drum, and then escapes to the outside of the drum unit. Note that the air that passes around the photosensitive drum contains foreign matter such as silica contained in the toner. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-190715 A [Patent Document 2] JP 2014-71272 A Summary of the Invention [Problem to be solved by the invention]

[0006] When the ventilation hole of Patent Document 2 is applied to the structure of Patent Document 1, the flow rate of the air flowing along the charging opening may vary between the upstream side and the downstream side.

[0007] Therefore, an object of the present disclosure is to suppress variation in the flow rate of air flowing along the charging opening. [Means for solving the problem]

[0008] In order to solve the above problem, the drum unit according to the first disclosure of the present application comprises a first photoconductor, a first charging electrode, a first charging frame, a first wall, a side frame, and a first film. The first photoconductor is rotatable about a rotation axis extending in the axial direction. The first charging electrode is an electrode for charging the first photoconductor and extends in the axial direction. The first charge frame holds a first charge electrode. The first charge frame has a first charge opening. The first charge opening is located on an opposite side of the first charge electrode from the first photoconductor. The first wall faces the first charged opening. The side frame supports one axial end of the first charger frame. The side frame has a first vent hole. The first vent hole opens in the axial direction. The first film extends from one of the first charge frame and the first wall to the other, and is positioned between the frame having the first wall and the first charge frame. When air flows from the first air hole toward the first charger frame, the air flows in the axial direction while being guided by the first charger frame, the first wall, and the first film.

[0009] According to the configuration of the first disclosure, the air is guided by the first charge frame, the first wall, and the first film to flow in the axial direction, thereby suppressing variation in the flow rate of the air flowing along the first charge opening between the upstream and downstream sides.

[0010] Further, the second disclosure of the present application has the following configuration in addition to the configuration of the drum unit of the first disclosure. When the drum unit is attached to the main body of the image forming apparatus, the first film is located above the first charging electrode.

[0011] Further, the third disclosure of the present application has the following configuration in addition to the configuration of the drum unit of the first disclosure. 2. The drum unit according to claim 1, wherein the first air hole is located between the first charging opening and the first film when viewed in the axial direction.

[0012] Further, the fourth disclosure of the present application has the following configuration in addition to the configuration of the drum unit of the first disclosure. The drum unit further includes a cleaner. The cleaner cleans the first charging electrode and is supported by the first charging frame so as to be axially movable. The first film is secured to a frame having a first wall. When the cleaner moves in the axial direction, the cleaner comes into contact with the first film and bends a portion of the first film.

[0013] Further, the fifth disclosure of the present application has the following configuration in addition to the configuration of the drum unit of the first disclosure. The frame is an end frame that supports one end of the side frame.

[0014] Further, the sixth disclosure of the present application has the following configuration in addition to the configuration of the drum unit of the fifth disclosure. The first film is secured to the end frame.

[0015] Further, the seventh disclosure of the present application has the following configuration in addition to the configuration of the drum unit of the first disclosure. The first film contacts the frame having the first wall and the first charged frame and fills the gap between the first charged frame and the first wall.

[0016] According to the configuration of the seventh disclosure, the first film contacts the frame and the first charged frame and fills the gap between the first charged frame and the first wall, and therefore, compared to a structure in which, for example, the first film is separated from the frame or the first charged frame, it is possible to prevent air that has passed through the first charged electrode from returning to the space surrounded by the first charged frame, the first wall, and the first film.

[0017] Further, the eighth disclosure of the present application has the following configuration in addition to the configuration of the drum unit of the first disclosure. The first film is made of polyurethane.

[0018] An image forming apparatus according to a ninth disclosure of the present application has the following configuration in addition to having any one of the drum units according to the first to eighth disclosures. The image forming apparatus includes a main body housing, a developing cartridge, and a second film. The main body housing movably supports the drum unit. The developing cartridge has a developing roller and is detachably attached to the drum unit. The drum unit includes a second photoconductor, a second charging electrode, and a second charging frame. The second photoconductor is rotatable about a rotation axis extending in the axial direction. The second charging electrode is an electrode for charging the second photoconductor and extends in the axial direction. A second charge frame holds a second charge electrode. The second charge frame has a second charge opening. The second charge opening is located on an opposite side of the second charge electrode from the second photoconductor. The developing cartridge has a developing housing. The developing housing contains toner and has a second wall facing the second charging opening. The side frame has a second air hole that opens in the axial direction. When the developing cartridge is attached to the drum unit, the second film extends from one of the second charger frame and the second wall to the other, and is positioned between the developing housing and the second charger frame. When air flows from the second vent hole toward the second charger frame, the air flows in the axial direction while being guided by the second charger frame, the second wall, and the second film.

[0019] According to the configuration of the ninth disclosure, the air is guided by the second charge frame, the second wall, and the second film to flow in the axial direction, thereby suppressing variation in the flow rate of the air flowing along the second charge opening between the upstream and downstream sides.

[0020] The tenth disclosure of the present application has the following configuration in addition to the configuration of the image forming apparatus of the ninth disclosure. The first film is axially larger than the second film.

[0021] According to the configuration of the tenth disclosure, the first film is larger than the second film in the axial direction, so that the long first film can effectively guide air along the first charging opening.

[0022] The eleventh disclosure of the present application has the following configuration in addition to the configuration of the image forming apparatus of the ninth disclosure. A second film is secured to a second charging frame.

[0023] The twelfth disclosure of the present application has the following configuration in addition to the configuration of the image forming apparatus of the ninth disclosure. The image forming apparatus further includes a fan for sending air into the drum unit through the first ventilation hole and the second ventilation hole.

[0024] An image forming apparatus according to a thirteenth disclosure of the present application includes a drum unit, a main body housing, a developing cartridge, and a film. The main body housing movably supports the drum unit. The developing cartridge has a developing roller and is detachably attached to the drum unit. The drum unit includes a photoconductor, a charging electrode, a charging frame, and a side frame. The photoreceptor is rotatable about an axially extending axis of rotation. The charging electrode is an electrode for charging the photoconductor and extends in the axial direction. The charge frame holds a charge electrode. The charge frame has a charge opening. The charge opening is located on an opposite side of the charge electrode from the photoreceptor. The side frame supports one axial end of the charger frame and has an air hole that opens in the axial direction. The developing cartridge has a developing housing. The developing housing contains toner and has a wall facing the charging opening. The film is located between the developing housing and the charging frame when the developing cartridge is attached to the drum unit. When air flows from the vent hole toward the charge frame, the air flowing from the vent hole flows in the axial direction due to the charge frame, the wall, and the film.

[0025] According to the configuration of the thirteenth disclosure, the air is guided by the charging frame, the wall, and the film to flow in the axial direction, thereby suppressing variation in the flow rate of the air flowing along the charging opening between the upstream and downstream sides.

[0026] The fourteenth disclosure of the present application has the following configuration in addition to the configuration of the image forming apparatus of the thirteenth disclosure. When the drum unit is attached to the main body of the image forming apparatus, the film is located above the charging electrode.

[0027] The fifteenth disclosure of the present application has the following configuration in addition to the configuration of the image forming apparatus of the thirteenth disclosure. The vent hole is located between the charging aperture and the film when viewed axially.

[0028] The sixteenth disclosure of the present application has the following configuration in addition to the configuration of the image forming apparatus of the thirteenth disclosure. The film contacts the developer housing and charging frame, filling the gap between the charging frame and the wall.

[0029] According to the configuration of the 16th disclosure, the film contacts the developing housing and the charging frame and fills the gap between the charging frame and the wall, so that air that has passed through the charging electrode can be prevented from returning to the space surrounded by the charging frame, the wall, and the film, compared to a structure in which the film is separated from the developing housing or the charging frame, for example.

[0030] The seventeenth disclosure of the present application has the following configuration in addition to the configuration of the image forming apparatus of the thirteenth disclosure. The film is secured to an electrostatic frame.

[0031] The eighteenth disclosure of the present application has the following configuration in addition to the configuration of the image forming apparatus of the thirteenth disclosure. The image forming apparatus further includes a fan for blowing air into the drum unit through the ventilation hole.

[0032] Further, a nineteenth disclosure of the present application has the following configuration in addition to the configuration of any one of the thirteenth to eighteenth disclosures. The film is made of polyurethane. Effect of the Invention

[0033] This makes it possible to suppress variation in the flow rate of air flowing along the charging opening. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 illustrates an image forming apparatus. [Diagram 2] FIG. 2 is a perspective view showing an outer frame of a main body housing. [Diagram 3] FIG. 2 is a perspective view showing an inner frame of a main body housing. [Figure 4] FIG. 4 is a side view of the first inner frame. [Diagram 5] FIG. 2 is a perspective view showing the drum unit. [Figure 6] FIG. 2 is a perspective view of the charger frame as viewed from one side in a first direction. [Figure 7] 11 is a perspective view of the charger frame as viewed from the other side in the first direction. FIG. [Figure 8] FIG. 4 is a cross-sectional view showing a structure around a charger corresponding to cyan. [Figure 9] FIG. 13 is a perspective view showing a fourth frame. [Figure 10] FIG. 4 is a cross-sectional view showing the structure around a charger for black. [Figure 11] FIG. 4 is a cross-sectional view showing the relationship between a cleaner and a first film. [Figure 12] FIG. 4 is a plan view showing the relationship between the cleaner and the first film. [Figure 13] FIG. 2 is a plan view showing the sizes of a first film and a second film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Next, the embodiment will be described in detail with reference to the drawings as appropriate. As shown in Fig. 1, the image forming apparatus 1 includes a main body housing 10 and a process unit 20. For convenience, the main body housing 10 is illustrated in Fig. 1 as being small in size.

[0036] In the drawings, the first direction, the second direction, and the axial direction are indicated by an arrow and the other direction without an arrow. The first direction is the direction in which the four photosensitive drums 32 are lined up. The axial direction is the direction in which the rotation axis X1 of the photosensitive drum 32 extends and intersects with the first direction. The second direction is the direction intersects with the first direction and the axial direction.

[0037] In this embodiment, the axial direction is perpendicular to the first direction. The second direction is perpendicular to the first direction and the axial direction. In this embodiment, one side of the first direction corresponds to the front side of the image forming apparatus 1. One side of the axial direction corresponds to the right side of the image forming apparatus 1. One side of the second direction corresponds to the upper side in the vertical direction.

[0038] The process unit 20 includes a drum unit 30 and four developing cartridges 40. The drum unit 30 is supported by the main body housing 10 so as to be movable in a first direction.

[0039] Drum unit 30 is movable in a first direction between a first position within main body housing 10 and a second position pulled out to one side in the first direction from main body housing 10. When drum unit 30 is located at the first position, image forming apparatus 1 is capable of printing.

[0040] The drum unit 30 includes a drum frame 31, four photosensitive drums 32, and four chargers 33. The photosensitive drums 32 are an example of a photosensitive member. The photosensitive drums 32 are rotatable about a rotation axis X1 that extends in the axial direction.

[0041] The charger 33 charges the photosensitive drum 32. The photosensitive drum 32 is exposed to laser light from an exposure device (not shown).

[0042] The four developer cartridges 40 each contain a different color toner. In this specification and drawings, when identifying components such as the developer cartridge 40 that correspond to the color of toner, the symbols Y, M, C, and K may be used to indicate yellow, magenta, cyan, and black, respectively.

[0043] In this embodiment, the photosensitive drum 32 corresponding to black corresponds to a first photosensitive member, and the photosensitive drums 32Y, 32M, and 32C corresponding to yellow, magenta, and cyan correspond to second photosensitive members, respectively.

[0044] The developing cartridge 40 is detachably attached to the drum unit 30. The developing cartridge 40 includes a developing housing 41 and a developing roller . The developing housing 41 contains toner.

[0045] The developing roller 42 is a roller that supplies toner to the photosensitive drum 32. The developing roller 42 comes into contact with the photosensitive drum 32.

[0046] The four developer cartridges 40 are aligned at intervals in the first direction. Specifically, the developer cartridges 40Y, 40M, 40C, and 40K are aligned in this order from one side in the first direction: 40Y, 40M, 40C, and 40K.

[0047] As shown in FIG. 2 and FIG. 3, the main body housing 10 has an outer frame 50 and an inner frame 60. The outer frame 50 has a first outer frame 51 located at one end in the axial direction of the main body housing 10. The first outer frame 51 has an intake port 51A and an exhaust port 51B.

[0048] The air intake ports 51A are a plurality of holes for taking air into the main body housing 10. The air intake ports 51A are located at an end portion on one side of the first outer frame 51 in the first direction and on the other side in the second direction.

[0049] The exhaust ports 51B are a plurality of holes for discharging air to the outside from within the main body housing 10. The exhaust ports 51B are located at an end portion of the first outer frame 51 on one side in the second direction and on the other side in the first direction.

[0050] The inner frame 60 is located inside the outer frame 50. The inner frame 60 has a first inner frame 61 adjacent to the first outer frame 51 on the inside in the axial direction.

[0051] An intake fan 71 and an exhaust fan 72 are attached to the first inner frame 61. The intake fan 71 is a fan for taking air into the main body housing 10 through the intake port 51A. The exhaust fan 72 is a fan for exhausting the air inside the inner frame 60 to the outside of the main body housing 10 through the exhaust port 51B.

[0052] The first inner frame 61 has a base wall 61A and a passage rib 61B. The base wall 61A is a plate-shaped wall and faces the first outer frame 51 in the axial direction.

[0053] The passage rib 61B is a rib for guiding the air taken in by the intake fan 71 to the vicinity of each charger 33 of the drum unit 30. The passage rib 61B protrudes from the base wall 61A toward the first outer frame 51. The passage rib 61B extends to one side in the second direction from the intake fan 71, then extends to the other side in the first direction, turns back to one side in the first direction at the charger 33K (see FIG. 1) that is on the othermost side in the first direction, then extends to one side in the first direction, and then extends to the other side in the second direction toward the intake fan 71.

[0054] 4, the base wall 61A has four holes 63. The holes 63 are holes for allowing air in the passage rib 61B to flow toward the charger 33. The holes 63Y, 63M, 63C, and 63K are provided at positions corresponding to the four chargers 33Y, 33M, 33C, and 33K, respectively.

[0055] As shown in Figures 1 and 5, the drum frame 31 has a first side frame F1, a second side frame F2, a third frame F3, a fourth frame F4 as an example of an end frame, and four charger frames F5.

[0056] The first side frame F1 is located at one end on one side in the axial direction of the drum unit 30. The first side frame F1 extends in a first direction. The first side frame F1 has four air holes H.

[0057] The ventilation hole H is a hole for taking air into the drum unit 30. The ventilation hole H is open in the axial direction. More specifically, the ventilation hole H penetrates the first side frame F1 in the axial direction.

[0058] The ventilation holes HY, HM, HC, and HK are provided at positions corresponding to the holes 63Y, 63M, 63C, and 63K of the first inner frame 61. In other words, the ventilation hole H corresponding to a predetermined color overlaps with the hole 63 corresponding to the predetermined color when viewed in the axial direction. For example, the ventilation hole HY corresponding to yellow overlaps with the hole 63Y corresponding to yellow when viewed in the axial direction.

[0059] In this embodiment, the ventilation hole HK corresponding to black corresponds to the first ventilation hole, and the ventilation holes HY, HM, and HC corresponding to yellow, magenta, and cyan correspond to the second ventilation holes, respectively.

[0060] The second side frame F2 is located at one end on the other axial side of the drum unit 30. The second side frame F2 extends in the first direction. The second side frame F2 faces the first side frame F1 in the axial direction with a gap therebetween.

[0061] The third frame F3 is located at one end of the drum unit 30 on one side in the first direction. The third frame F3 connects one end of the first side frame F1 on one side in the first direction and one end of the second side frame F2 on one side in the first direction.

[0062] The fourth frame F4 is located at one end of the drum unit 30 on the other side in the first direction. The fourth frame F4 connects the end of the first side frame F1 on the other side in the first direction to the end of the second side frame F2 on the other side in the first direction. In other words, the fourth frame F4 supports the end of the first side frame F1 on the other side in the first direction.

[0063] The charging frame F5 is a frame that holds the charger 33. The charging frames F5Y, F5M, F5C, and F5K respectively hold the chargers 33Y, 33M, 33C, and 33K of the corresponding colors.

[0064] In this embodiment, the charge frame F5K corresponding to black corresponds to the first charge frame, and the charge frames F5Y, F5M, and F5C corresponding to yellow, magenta, and cyan correspond to the second charge frames, respectively.

[0065] The four charge frames F5 are located between the third frame F3 and the fourth frame F4 in the first direction. The four charge frames F5 are arranged at intervals in the first direction. Each charge frame F5 connects the first side frame F1 and the second side frame F2. In other words, the first side frame F1 supports one end of the charge frame F5 in the axial direction. The second side frame F2 supports the other end of the charge frame F5 in the axial direction.

[0066] As shown in FIGS. 6 and 7, the charger frame F5 has a cylindrical guide portion F51 and a charger opening F52. The guide portion F51 is a guide that guides the air entering through the ventilation hole H (see FIG. 5) of the first side frame F1 toward the charging opening F52. The guide portion F51 has a hole penetrating in the axial direction. The guide portion F51 is located at one end of the charging frame F5 in the axial direction.

[0067] 7 and 8, the holes of the guide portion F51 overlap with the corresponding ventilation holes H when viewed from the axial direction. For example, the holes of the guide portion F51 of the charging frame F5C corresponding to cyan overlap with the ventilation hole HC corresponding to cyan when viewed from the axial direction.

[0068] 8, the charger 33 has a charging wire 331 as an example of a charging electrode, and a grid electrode 332. The charging wire 331 and the grid electrode 332 are electrodes for charging the photosensitive drum 32.

[0069] The charged wire 331 and the grid electrode 332 extend in the axial direction. The charged frame F5 holds the charged wire 331 and the grid electrode 332.

[0070] In this embodiment, the charged wire 331 corresponding to black corresponds to a first charging electrode, and the charged wires 331 corresponding to yellow, magenta, and cyan correspond to second charging electrodes.

[0071] The charging opening F52 is located on the opposite side of the charging wire 331 to the photosensitive drum 32. In particular, the charging opening F52 corresponding to a predetermined color is located on the opposite side of the photosensitive drum 32 corresponding to the predetermined color to the charging wire 331 corresponding to the predetermined color. For example, the charging opening F52 corresponding to cyan is located on the opposite side of the photosensitive drum 32C corresponding to cyan to the charging wire 331 corresponding to cyan.

[0072] 7, the charging opening F52 extends in the axial direction. The charging opening F52 exposes the charging wire 331 to the outside of the charging frame F5.

[0073] In this embodiment, the charging aperture F52 corresponding to black corresponds to the first charging aperture, and the charging apertures F52 corresponding to yellow, magenta, and cyan correspond to the second charging apertures, respectively.

[0074] 8, the developing housing 41 has a second wall W2 as an example of a wall. The second wall W2 faces the charging opening F52 with a gap therebetween. The developing housings 41K, 41C, and 41M corresponding to black, cyan, and magenta each have a second wall W2.

[0075] The second wall W2 of the developing housing 41K corresponding to black faces the charging opening F52 of the charging frame F5C corresponding to cyan. Although not shown, the second wall W2 of the developing housing 41C corresponding to cyan faces the charging opening F52 of the charging frame F5M corresponding to magenta. The second wall W2 of the developing housing 41M corresponding to magenta faces the charging opening F52 of the charging frame F5Y corresponding to yellow. The structure around the second wall W2 is the same for each of the colors black, cyan, and magenta, so in the following explanation, the structure corresponding to black will be explained as a representative.

[0076] The second wall W2 has a center portion W21, one side portion W22, and the other side portion W23. The center portion W21 has a portion that faces the charging opening F52 of the charging frame F5C in a direction from the rotation center of the photosensitive drum 32C toward the charging wire 331. The center portion W21 extends obliquely toward one side in the first direction and one side in the second direction along the surface of an end of the charging frame F5C on one side in the second direction.

[0077] The one side portion W22 extends from one end of the central portion W21 in the first direction toward the charger frame F5C. The other side portion W23 extends from the other end of the central portion W21 in the first direction toward the charger frame F5C.

[0078] A second film FL2, which is an example of a film, is fixed to each of the charging frames F5Y, F5M, and F5C corresponding to yellow, magenta, and cyan (see also FIGS. 5 to 7). The dimension of the second film FL2 in the axial direction is larger than the dimensions in other directions.

[0079] When the developing cartridge 40K corresponding to black is attached to the drum unit 30, the second film FL2 extends from the charging frame F5C corresponding to cyan toward the second wall W2 and is located between the developing housing 41K and the charging frame F5C. More specifically, the second film FL2 extends obliquely from the charging frame F5C toward the other side in the first direction and toward one side in the second direction. The tip of the second film FL2 contacts one side portion W22 of the second wall W2 to fill the gap between the charging frame F5C and the second wall W2.

[0080] When the drum unit 30 is attached to the main body housing 10, the second film FL2 is located on one side in the second direction, i.e., above, the charging wire 331. The ventilation hole HC corresponding to cyan is located between the charging opening F52 corresponding to cyan and the second film FL2, as viewed from the axial direction. In other words, the ventilation hole HC corresponding to cyan is located between the end on the other side in the second direction of the charging opening F52 corresponding to cyan and the end on one side in the second direction of the second film FL2, as viewed from the axial direction.

[0081] 9, a first film FL1 is fixed to the fourth frame F4. The first film FL1 and the second film FL2 are each made of polyurethane.

[0082] As shown in FIG. 10, the fourth frame F4 has a first wall W1. The first wall W1 faces the charging opening F52 corresponding to black with a gap therebetween. The first wall W1 has a center portion W11, one side portion W12, and the other side portion W13.

[0083] The central portion W11 has a portion that faces the charging opening F52 of the charging frame F5K in the direction from the rotation center of the photosensitive drum 32K toward the charging wire 331. The central portion W11 extends obliquely toward one side in the first direction and one side in the second direction so as to follow the surface of one end of the charging frame F5K on one side in the second direction.

[0084] The one side portion W12 extends from one end of the central portion W11 in the first direction toward the charger frame F5K. The other side portion W13 extends from the other end of the central portion W11 in the first direction toward the charger frame F5K.

[0085] The first film FL1 extends from one side portion W12 of the first wall W1 toward the other side in the second direction. In other words, the first film FL1 extends from the first wall W1 toward the charged frame F5K. The first film FL1 is located between the first wall W1 and the charged frame F5K. More specifically, a part of the first film FL1 is located between the first wall W1 and the charged frame F5K. An end of the first film FL1 contacts the charged frame F5K and fills the gap between the charged frame F5K and the first wall W1.

[0086] When the drum unit 30 is attached to the main body housing 10, the first film FL1 is located on one side in the first direction, i.e., above the charged wire 331. The ventilation hole HK corresponding to black is located between the charging opening F52 corresponding to black and the first film FL1 when viewed from the axial direction. In other words, the ventilation hole HK corresponding to black is located between the end on the other side in the second direction of the charging opening F52 corresponding to black and the end on one side in the second direction of the first film FL1 when viewed from the axial direction.

[0087] 11 and 12, the drum unit 30 further includes a cleaner CL. The cleaner CL is a member that cleans the charging wire 331. The cleaner CL is supported by the charging frame F5K so as to be movable in the axial direction. When the cleaner CL moves in the axial direction, it comes into contact with the first film FL1 and bends a part of the first film FL1.

[0088] 13, the first film FL1 is larger than the second film FL2 in the axial direction. Specifically, the dimension L1 of the first film FL1 in the axial direction is larger than the dimension L2 of the second film FL2 in the axial direction.

[0089] Next, the air flow when the intake fan 71 and the exhaust fan 72 are driven will be described. As shown in Fig. 3, when intake fan 71 and exhaust fan 72 are driven, air outside main body housing 10 is sucked into main body housing 10 through intake port 51A as shown in Fig. 2. The air that has entered main body housing 10 through intake port 51A passes through a passage partitioned by passage rib 61B and flows toward drum unit 30 through holes 63Y, 63M, 63C, and 63K as shown in Fig. 4.

[0090] The air that has passed through the holes 63Y, 63M, 63C, and 63K flows toward the charger 33 through the ventilation holes HY, HM, HC, and HK shown in Fig. 5. As shown in Fig. 10, the air that has passed through the ventilation hole HK passes through the guide portion F51, and then flows along the axial direction in the space surrounded by the first wall W1, the charge frame F5K, and the first film FL1. In other words, when air flows from the ventilation hole HK toward the charge frame F5K, the air flows in the axial direction while being guided by the charge frame F5K, the first wall W1, and the first film FL1.

[0091] 8, the air that has passed through the ventilation hole HC passes through the guide portion F51 and then flows in the axial direction in the space surrounded by the second wall W2, the charged frame F5C, and the second film FL2. In other words, when air flows from the ventilation hole HC toward the charged frame F5C, the air flows in the axial direction while being guided by the charged frame F5C, the second wall W2, and the second film FL2.

[0092] The air flowing in the axial direction flows along the charging opening F52 and passes through the charging opening F52 toward the photosensitive drum 32. The air that hits the photosensitive drum 32 passes between the fourth frame F4 and the developing housing 41 or between adjacent developing housings 41 and flows toward one side in the second direction.

[0093] 1, the air flowing toward one side in the second direction is discharged from drum unit 30 to one side in the second direction, and then flows toward exhaust fan 72 on the other side in the first direction. The air is then discharged to the outside of main body housing 10 from exhaust port 51B shown in FIG.

[0094] As described above, according to this embodiment, the following effects can be obtained. By configuring the air to flow in the axial direction while being guided by the charge frame F5K, the first wall W1, and the first film FL1, variation in the amount of air flowing along the charge opening F52 corresponding to black can be suppressed.

[0095] Here, the flow rate of air flowing along the charging opening tends to be smaller downstream than upstream. In this case, the air that has passed around the photosensitive drum returns to the downstream area where the flow rate is smaller through the gap between the developer cartridge and the charging frame, causing foreign matter to adhere to part of the charging wire. If foreign matter adheres unevenly to the charging wire, the charging performance will deteriorate.

[0096] In contrast, in this embodiment, since the variation in the flow rate of the air flowing along the charging opening F52 can be suppressed, it is possible to suppress foreign matter from adhering unevenly to the charging wire 331 corresponding to black.

[0097] Since the first film FL1 contacts the first wall W1 and the charged frame F5K and fills the gap between the charged frame F5K and the first wall W1, it is possible to prevent air that has passed through the charged wire 331 from returning to the space surrounded by the charged frame F5K, the first wall W1, and the first film FL1, compared to a structure in which, for example, the first film is separated from the first wall or the first charged frame.

[0098] By configuring the air to flow in the axial direction while being guided by the charged frame F5C, the second wall W2, and the second film FL2, the flow rate of the air flowing along the charged opening F52 corresponding to cyan is prevented from differing significantly between the upstream and downstream sides, thereby preventing foreign matter from adhering unevenly to the charged wire 331 corresponding to cyan.

[0099] Since the first film FL1 is larger than the second film FL2 in the axial direction, the long first film FL1 can effectively guide air along the charging opening F52 corresponding to black.

[0100] The present disclosure is not limited to the above-described embodiment, but can be used in various forms as exemplified below. The charging electrode is not limited to a charging wire, but may be, for example, saw-shaped. The photoconductor is not limited to a photoconductor drum, but may be, for example, a belt-shaped one.

[0101] The frame having the first wall is not limited to an end frame, but may be any frame, for example, another frame disposed between the third frame and the fourth frame.

[0102] The first film may be fixed to the first charger frame, in which case the first film may extend from the first charger frame towards the first wall.

[0103] The second film may be fixed to the developing housing, in which case the second film may extend from the second wall of the developing housing towards the second charger frame.

[0104] The leading edge of the first film may be slightly spaced from the frame having the first wall or the first charge frame. When the developing cartridge is attached to the drum unit, the leading edge of the second film may be slightly spaced from the developing housing or the second charge frame.

[0105] Although intake fan 71 and exhaust fan 72 are illustrated as fans for sending air into the drum unit from the ventilation holes, the fan may be only one of the intake fan and the exhaust fan.

[0106] The image forming apparatus is not limited to a laser printer, but may be other image forming apparatuses such as a copying machine or a multifunction machine.

[0107] The elements described in the above-mentioned embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0108] 30 Drum unit 32K Photosensitive drum 331 Charged Wire F1 1st side frame F5K Electrostatic Frame F52 Electrostatic opening FL1 1st film HK Ventilation Hole W1 1st wall X1 Rotation Axis

Claims

1. a first photoconductor rotatable about a rotation axis extending in an axial direction; a first charging electrode for charging the first photoconductor, the first charging electrode extending in the axial direction; a first charging frame that holds the first charging electrode, the first charging frame having a first charging opening located on a side opposite the first photoconductor with respect to the first charging electrode; a first wall facing the first charging opening; a side frame supporting one end of the first charger frame in the axial direction, the side frame having a first air hole opening in the axial direction; a first film extending from one of the first charge frame and the first wall toward the other, the first film being located between a frame having the first wall and the first charge frame; A drum unit characterized in that, when air flows from the first air vent toward the first charging frame, the air flows in the axial direction while being guided by the first charging frame, the first wall, and the first film.

2. 2. The drum unit according to claim 1, wherein the first film is positioned above the first charging electrode when the drum unit is attached to a main body of an image forming apparatus.

3. 2. The drum unit according to claim 1, wherein the first air hole is located between the first charging opening and the first film when viewed in the axial direction.

4. a cleaner for cleaning the first charging electrode, the cleaner being supported by the first charging frame so as to be movable in the axial direction; the first film is secured to a frame having the first wall; 2. The drum unit according to claim 1, wherein the cleaner moves in the axial direction while coming into contact with the first film and bending a part of the first film.

5. 2. The drum unit according to claim 1, wherein the frame is an end frame that supports one end of the side frame.

6. 6. The drum unit according to claim 5, wherein the first film is fixed to the end frame.

7. 2. The drum unit according to claim 1, wherein the first film contacts the frame having the first wall and the first charging frame, and fills a gap between the first charging frame and the first wall.

8. 2. The drum unit according to claim 1, wherein the first film is made of polyurethane.

9. A drum unit according to any one of claims 1 to 8, a main body housing that movably supports the drum unit; a developing cartridge having a developing roller, the developing cartridge being detachably attached to the drum unit; a second film, The drum unit includes: a second photoconductor rotatable about a rotation axis extending in the axial direction; a second charging electrode for charging the second photoconductor, the second charging electrode extending in the axial direction; a second charging frame that holds the second charging electrode, the second charging frame having a second charging opening located on a side opposite the second photoconductor with respect to the second charging electrode; The developing cartridge is a developing housing for accommodating toner, the developing housing having a second wall facing the second charging opening; The side frame has a second air hole that opens in the axial direction, when the developing cartridge is attached to the drum unit, the second film extends from one of the second charger frame and the second wall to the other, and is positioned between the developing housing and the second charger frame; an image forming apparatus characterized in that, when air flows from the second air vent toward the second charged frame, the air flows in the axial direction while being guided by the second charged frame, the second wall, and the second film.

10. 10. The image forming apparatus according to claim 9, wherein the first film is larger than the second film in the axial direction.

11. 10. The image forming apparatus according to claim 9, wherein the second film is fixed to the second charging frame.

12. 10. The image forming apparatus according to claim 9, further comprising a fan for blowing air into the drum unit through the first ventilation hole and the second ventilation hole.

13. A drum unit, a main body housing that movably supports the drum unit; a developing cartridge having a developing roller, the developing cartridge being detachably attached to the drum unit; A film, The drum unit includes: a photoreceptor rotatable about an axially extending axis of rotation; a charging electrode for charging the photoconductor, the charging electrode extending in the axial direction; a charging frame for holding the charging electrode, the charging frame having a charging opening located on the opposite side of the charging electrode from the photoconductor; a side frame supporting one end of the charger frame in the axial direction, the side frame having an air hole opening in the axial direction, The developing cartridge is a developing housing for accommodating toner, the developing housing having a wall facing the charging opening; the film is located between the developing housing and the charging frame when the developing cartridge is attached to the drum unit, an image forming apparatus characterized in that, when air flows from the air vent toward the charging frame, the air flowing from the air vent flows in the axial direction due to the charging frame, the wall, and the film.

14. 14. The image forming apparatus according to claim 13, wherein the film is located above the charging electrode when the drum unit is attached to a main body of the image forming apparatus.

15. 14. The image forming apparatus according to claim 13, wherein the air hole is located between the charging opening and the film when viewed in the axial direction.

16. 14. The image forming apparatus according to claim 13, wherein the film contacts the developing housing and the charging frame, and fills a gap between the charging frame and the wall.

17. 14. The image forming apparatus according to claim 13, wherein the film is fixed to the charging frame.

18. 14. The image forming apparatus according to claim 13, further comprising a fan for blowing air into the drum unit through the ventilation hole.

19. 19. The image forming apparatus according to claim 13, wherein the film is made of polyurethane.

Images