Drum unit

Abstract

To provide a drum unit capable of enhancing position accuracy of a second cleaning roller and a cleaning member.SOLUTION: A drum unit includes: a photosensitive drum; a first cleaning roller 110 having a rotatable first shaft 111 and in contact with a peripheral surface of the photosensitive drum; a second cleaning roller 120 having a rotatable second shaft 121 and in contact with a peripheral surface of the first cleaning roller 110; a first bearing B1 having a first hole 171A into which one end 111A of the first shaft 111 fits and a second hole 172A into which one end 121A of the second shaft 121 fits; a second bearing B2 having a third hole 181A into which the one end 121A of the second shaft 121 fits; a cleaning pad 130 (cleaning member ) in contact with a peripheral surface of the second cleaning roller 120; a plate 160 supporting the cleaning pad 130; and a first screw 191 fixing the plate 160 to the second bearing B2.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a drum unit including a first cleaning roller, a second cleaning roller, and a cleaning member for cleaning a photosensitive drum. [Background technology]

[0002] Conventionally, a drum unit is known that includes a photosensitive drum, a first cleaning roller that cleans the photosensitive drum, a second cleaning roller that contacts the peripheral surface of the first cleaning roller, a cleaning member that contacts the peripheral surface of the second cleaning roller, bearings that support the first cleaning roller and the second cleaning roller, and a holder that holds the cleaning member and the bearings (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-068020 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional configuration, the first cleaning roller and the second cleaning roller are supported by a single bearing, so the positional accuracy of the first cleaning roller and the second cleaning roller is high. On the other hand, in order to improve the cleaning performance of the first cleaning roller, the second cleaning roller and the cleaning member, it is desirable to also have high positional accuracy of the second cleaning roller and the cleaning member.

[0005] It is therefore an object of the present invention to provide a drum unit that can improve the positioning accuracy of the second cleaning roller and the cleaning member. [Means for solving the problem]

[0006] A drum unit for achieving the above-mentioned object includes a photosensitive drum rotatable about a drum axis extending in a first direction, a first cleaning roller having a first shaft rotatable about a first axis extending in the first direction, the first cleaning roller contacting a peripheral surface of the photosensitive drum, a second cleaning roller having a second shaft rotatable about a second axis extending in the first direction, the second cleaning roller contacting a peripheral surface of the first cleaning roller, a first bearing having a first hole into which one end of the first shaft in the first direction fits and a second hole into which one end of the second shaft in the first direction fits, a second bearing having a third hole into which one end of the second shaft in the first direction fits, a cleaning member in contact with the peripheral surface of the second cleaning roller, a plate supporting the cleaning member, and a first screw fixing the plate to the second bearing.

[0007] According to this configuration, the first bearing can improve the positional accuracy of the first cleaning roller and the second cleaning roller. Furthermore, the second bearing that supports the second cleaning roller and the plate that supports the cleaning member are fixed with the first screw, so that the positional accuracy of the second cleaning roller and the cleaning member can be improved.

[0008] The cleaning member may be a cleaning pad.

[0009] The cleaning pad may be configured to be located between the second cleaning roller and the plate in a second direction intersecting the first direction.

[0010] According to this, the reaction force that the cleaning pad receives from the second cleaning roller in the second direction can be received by the plate, so that the cleaning pad can be prevented from moving away from the second cleaning roller.

[0011] The plate may have an opening penetrating in the second direction, through which the first screw passes, and the second bearing may have a screw hole into which the first screw is fixed.

[0012] This allows the first screw to be tightened in the second direction so as to press the cleaning pad against the second cleaning roller, thereby preventing the cleaning pad, which receives a reaction force from the second cleaning roller, from moving away from the second cleaning roller and allowing the cleaning pad to firmly contact the circumferential surface of the second cleaning roller.

[0013] The second direction may be configured to be perpendicular to the first direction.

[0014] The drum unit may further include an adhesive tape that adheres the cleaning pad to the plate, the adhesive tape being located between the cleaning pad and the plate in the second direction.

[0015] According to this, in the second direction, the cleaning pad is pressed against the plate via the adhesive tape by the reaction force that the cleaning pad receives from the second cleaning roller, so that when the cleaning pad is adhered with the adhesive tape, the cleaning pad is unlikely to peel off from the plate.

[0016] In addition, the first cleaning roller can be configured to clean paper dust from the peripheral surface of the photosensitive drum, the second cleaning roller can be configured to clean paper dust from the peripheral surface of the first cleaning roller, and the cleaning pad can be configured to clean paper dust from the peripheral surface of the second cleaning roller.

[0017] The cleaning pad may also be made of silicone rubber.

[0018] The cleaning pad may have a corner that comes into contact with the circumferential surface of the second cleaning roller.

[0019] According to this, the cleaning pad and the circumferential surface of the second cleaning roller can be brought into line contact with each other, so that the deposits on the circumferential surface of the second cleaning roller can be securely scraped off by the cleaning pad made of silicone rubber.

[0020] The angle of the corners may be set to be equal to or greater than 10 degrees and equal to or less than 170 degrees.

[0021] The second bearing can have a first convex portion protruding radially from the second shaft, and a second convex portion protruding radially from the second shaft and positioned away from the first convex portion in the circumferential direction of the second shaft, and the first bearing can be configured to have a first recess into which the first convex portion fits, and a second recess into which the second convex portion fits.

[0022] According to this, when manufacturing the drum unit, the first convex portion and the first concave portion, and the second convex portion and the second concave portion are fitted together, respectively, so that the relative rotation between the first bearing and the second bearing can be suppressed and the positions of the first bearing and the second bearing can be provisionally determined. This makes it easier to assemble the drum unit.

[0023] The drum unit further includes a housing that contains paper dust collected by the first cleaning roller from the peripheral surface of the photosensitive drum, and a drum frame that supports the photosensitive drum and the housing, and the drum frame can be configured to have a frame opening that exposes part of the housing when the housing is supported by the drum frame.

[0024] This allows the size of the housing to be increased, and therefore the capacity of the portion of the housing that stores paper dust can be increased.

[0025] The drum frame may have a plurality of frame openings, the plurality of frame openings being spaced apart from one another in the first direction.

[0026] This makes it possible to increase the capacity of the portion of the housing that stores paper dust while ensuring the rigidity of the drum frame.

[0027] The drum unit can further include a third bearing having a fourth hole into which the other end of the first shaft in the first direction fits and a fifth hole into which the other end of the second shaft in the first direction fits, a fourth bearing having a sixth hole into which the other end of the second shaft in the first direction fits, and a second screw that fixes the plate to the fourth bearing.

[0028] This allows the first and third bearings to improve the positional accuracy of the first and second cleaning rollers. Also, the second and fourth bearings that support the second cleaning roller and the plate 160 are fixed with the first and second screws, thereby improving the positional accuracy of the second cleaning roller and the cleaning member.

[0029] The fourth bearing may have the same shape as the second bearing.

[0030] According to this, since the second bearing and the fourth bearing are common parts, it is possible to reduce the number of types of parts required for manufacturing the drum unit.

[0031] The shape of the third bearing may be the same as that of the first bearing.

[0032] According to this, since the first bearing and the third bearing are common parts, it is possible to reduce the number of types of parts required for manufacturing the drum unit. Effect of the Invention

[0033] According to the drum unit of the present disclosure, the positional accuracy of the second cleaning roller and the cleaning member can be improved. [Brief description of the drawings]

[0034] [Figure 1]1 is a cross-sectional view of an image forming apparatus including a drum cartridge as an example of a drum unit of an embodiment. [Diagram 2] 2 is an enlarged cross-sectional view showing the photosensitive drum and its surroundings of the drum cartridge. FIG. [Diagram 3] FIG. 2 is an enlarged view of the cleaning pad and its surrounding area of ​​the cleaning unit. [Figure 4] FIG. 2 is a perspective view showing the drum cartridge in an upside-down state. [Diagram 5] FIG. 2 is a perspective view of a cleaning unit. [Figure 6] FIG. 2 is an exploded perspective view of the cleaning unit. [Figure 7] FIG. 2 is a perspective view showing a first bearing, a second bearing, and peripheral members thereof. [Figure 8] FIG. 4 is a perspective view showing a third bearing, a fourth bearing, and their surrounding members. [Figure 9] 1A is a side view showing a first bearing, FIG. 1B is a side view showing a second bearing, and FIG. 1C is a side view showing the second bearing assembled to the first bearing. [Figure 10] 4 is a cross-sectional view of the vicinity of a first screw of the cleaning unit. FIG. [Figure 11] 1A is a cross-sectional view of a cleaning unit, and FIG. [Figure 12] FIG. 2 is a diagram showing a photosensitive drum, a first cleaning roller, a second cleaning roller, and a cleaning pad. [Figure 13] FIG. 11 is a perspective view showing a cleaning member according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Next, an embodiment of the drum unit will be described in detail with reference to the drawings. 1, the image forming apparatus 1 includes a main body housing 2, a sheet supply unit 3, an exposure device 4, a drum cartridge 6 as an example of a drum unit, a developing cartridge 7, and a fixing device 8. The main body housing 2 has a front cover 21 that can be opened and closed.

[0036] The sheet supply unit 3 is located at the bottom inside the main body housing 2. The sheet supply unit 3 includes a sheet tray 31, a pressure plate 32, and a sheet supply mechanism 33. The sheet tray 31 is detachable from the main body housing 2. The sheet supply unit 3 moves the sheets S stored in the sheet tray 31 toward the sheet supply mechanism 33 using the pressure plate 32, and the sheet supply mechanism 33 supplies the sheets S one by one toward the drum cartridge 6 (between a photosensitive drum 61 and a transfer roller 63 described later).

[0037] The exposure device 4 is located at the upper part inside the main body housing 2. The exposure device 4 includes a light source device (not shown), a polygon mirror (not shown) with its reference numerals omitted, a lens, a reflecting mirror, etc. The exposure device 4 exposes the surface of the photosensitive drum 61 by irradiating the surface of the photosensitive drum 61 with a light beam (not shown) with a virtual line.

[0038] The drum cartridge 6 is located below the exposure device 4. The drum cartridge 6 is detachable from the main body housing 2 through an opening of the main body housing 2 with the front cover 21 open. The drum cartridge 6 includes a photosensitive drum 61, a charger 62, and a transfer roller 63.

[0039] The developing cartridge 7 is detachably attached to the drum cartridge 6. The developing cartridge 7 is detachably attached to the main body housing 2 while attached to the drum cartridge 6. The developing cartridge 7 includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, a toner storage section 74 that stores toner, and an agitator 75. The agitator 75 supplies the toner stored in the toner storage section 74 to the supply roller 72. The supply roller 72 supplies the toner supplied to the supply roller 72 to the developing roller 71 by the rotation of the supply roller 72. The developing roller 71 causes the toner supplied to the developing roller 71 to enter between the developing roller 71 and the layer thickness regulating blade 73 by the rotation of the developing roller 71. The layer thickness regulating blade 73 carries the toner on the developing roller 71 as a thin layer of a constant thickness.

[0040] The fixing device 8 is located behind the drum cartridge 6. The fixing device 8 includes a heating unit 81 and a pressure roller 82. The heating unit 81 includes a heater, a fixing belt, a nip plate, etc., the reference numerals of which are omitted. The pressure roller 82 is pressed by the heating unit 81, and sandwiches the fixing belt between the pressure roller 82 and the nip plate of the heating unit 81.

[0041] The charger 62 uniformly charges the surface of the photosensitive drum 61. The exposure device 4 exposes the surface of the photosensitive drum 61 to light, thereby forming an electrostatic latent image based on image data on the photosensitive drum 61. The development roller 71 supplies the toner carried on the development roller 71 to the electrostatic latent image on the photosensitive drum 61, thereby forming a toner image on the photosensitive drum 61.

[0042] The photosensitive drum 61 and the transfer roller 63 transport the sheet S supplied from the sheet supply unit 3 between the photosensitive drum 61 and the transfer roller 63. At this time, the transfer roller 63 transfers the toner image on the photosensitive drum 61 to the sheet S. The heating unit 81 and the pressure roller 82 transport the sheet S, on which the toner image has been transferred, between the heating unit 81 and the pressure roller 82. At this time, the heating unit 81 and the pressure roller 82 fix the toner image to the sheet S. The transport roller 23 and the discharge roller 24 discharge the sheet S, on which the toner image has been fixed, onto the discharge tray 22.

[0043] As shown in FIG. 2, the drum cartridge 6 further includes a cleaning unit 64 and a drum frame 65 in addition to the photosensitive drum 61 and the like.

[0044] The photosensitive drum 61 is rotatable about a drum shaft 61A extending in a first direction (see FIG. 4). In this embodiment, the first direction is the same as the left-right direction of the image forming apparatus 1. The photosensitive drum 61 has a cylindrical base tube 61B made of metal and a photosensitive layer 61C applied to the outer circumferential surface of the base tube 61B.

[0045] The drum frame 65 supports the photosensitive drum 61 and a housing 150 (described later) of the cleaning unit 64. The drum frame 65 supports the photosensitive drum 61 rotatably.

[0046] The cleaning unit 64 cleans paper dust adhering to the peripheral surface of the photosensitive drum 61. The cleaning unit 64 includes a first cleaning roller 110, a second cleaning roller 120, a cleaning pad 130 as an example of a cleaning member, a cleaning sheet 140, and a housing 150.

[0047] The first cleaning roller 110 cleans the paper dust on the circumferential surface of the photosensitive drum 61. More specifically, the first cleaning roller 110 collects the powder-like paper dust adhering to the circumferential surface of the photosensitive drum 61. The first cleaning roller 110 has a first shaft 111 and a first roller body 112. The first shaft 111 is rotatable about a first axis A1 extending in a first direction. The first shaft 111 is made of metal. The first roller body 112 is made of conductive rubber or the like, and is formed so as to cover the first shaft 111. As an example, the first roller body 112 is made of foamed silicone rubber. In the first cleaning roller 110, the circumferential surface of the first roller body 112 comes into contact with the circumferential surface of the photosensitive drum 61.

[0048] The second cleaning roller 120 cleans the paper powder on the circumferential surface of the first cleaning roller 110. More specifically, the second cleaning roller 120 collects the paper powder adhering to the circumferential surface of the first cleaning roller 110. The second cleaning roller 120 has a second shaft 121 and a second roller body 122. The second shaft 121 is rotatable about a second axis A2 extending in the first direction. The second shaft 121 and the second roller body 122 are made of metal and are integrally formed. In the second cleaning roller 120, the circumferential surface of the second roller body 122 comes into contact with the circumferential surface of the first roller body 112 of the first cleaning roller 110.

[0049] The cleaning pad 130 cleans paper dust on the peripheral surface of the second cleaning roller 120. More specifically, the cleaning pad 130 scrapes off the paper dust adhering to the peripheral surface of the second cleaning roller 120. The paper dust scraped off from the peripheral surface of the second cleaning roller 120 by the cleaning pad 130 is stored in the paper dust storage section 151 of the housing 150. The cleaning pad 130 is a rectangular parallelepiped member that is long in the first direction, and is made of silicone rubber.

[0050] The cleaning pad 130 contacts the circumferential surface of the second cleaning roller 120. More specifically, as shown in FIG. 3, the cleaning pad 130 has a corner 131. The corner 131 of the cleaning pad 130 contacts the circumferential surface of the second roller body 122 of the second cleaning roller 120. In a cross section of the cleaning pad 130 cut by a plane perpendicular to the first direction, the angle θ of the corner 131 is preferably 10 degrees or more and 170 degrees or less. More preferably, the angle θ of the corner 131 is 45 degrees or more and 135 degrees or less. Even more preferably, the angle θ of the corner 131 is 80 degrees or more and 100 degrees or less. Most preferably, the angle θ of the corner 131 is 90 degrees.

[0051] In this embodiment, the angle θ of the corner 131 is approximately 90 degrees. When the angle θ of the corner 131 is close to 90 degrees, it becomes easier to manufacture the rectangular parallelepiped cleaning pad 130 made of silicone rubber. Note that in FIG. 3 and other figures, the corner 131 of the cleaning pad 130 and the second cleaning roller 120 are illustrated overlapping each other, but in reality, the cleaning pad 130 is elastically deformed so as to be crushed when the corner 131 is pressed against the circumferential surface of the second cleaning roller 120.

[0052] Returning to FIG. 2, the cleaning sheet 140 cleans paper dust from the circumferential surface of the photosensitive drum 61. More specifically, the cleaning sheet 140 collects fibrous paper dust adhering to the circumferential surface of the photosensitive drum 61. The cleaning sheet 140 has a flocked cloth 141 that is long in the first direction. The flocked cloth 141 of the cleaning sheet 140 comes into contact with the circumferential surface of the photosensitive drum 61.

[0053] The housing 150 supports the first cleaning roller 110, the second cleaning roller 120, the cleaning pad 130, and the cleaning sheet 140. In detail, the housing 150 rotatably supports the first cleaning roller 110 and the second cleaning roller 120 via bearings B1 to B4 (see FIG. 6) described later. In addition, the housing 150 supports the cleaning pad 130 via a plate 160 described later.

[0054] The housing 150 has a paper dust storage section 151 that stores paper dust collected from the circumferential surface of the photosensitive drum 61 by the first cleaning roller 110 or the like. The housing 150 also has a first housing 152 having the paper dust storage section 151, and a second housing 153 assembled to the first housing 152.

[0055] FIG. 4 shows the drum cartridge 6 upside down. As shown in FIG. 4, the drum frame 65 has a frame opening 65A. More specifically, the drum frame 65 has a plurality of frame openings 65A. Specifically, the drum frame 65 has four frame openings 65A. Each frame opening 65A has a rectangular shape that is long in the first direction. The frame openings 65A are positioned at intervals in the first direction. The portions between the adjacent frame openings 65A form part of the wall of the drum frame 65.

[0056] The frame opening 65A exposes a part of the housing 150 of the cleaning unit 64 when the housing 150 is supported by the drum frame 65. In detail, as shown in Fig. 2, when the housing 150 is supported by the drum frame 65, a bottom portion 152B that is a part of the first housing 152 fits into the frame opening 65A. Moreover, the bottom portion 152B of the first housing 152 protrudes outward from the frame opening 65A beyond the outer surface of the drum frame 65.

[0057] As shown in FIGS. 5 and 6, the cleaning unit 64 further includes a plate 160, a first bearing B1, a second bearing B2, a third bearing B3, and a fourth bearing B4.

[0058] The plate 160 supports the cleaning pad 130. The plate 160 is a substantially L-shaped member made of a metal plate. In detail, the plate 160 has a support portion 160A and an extension portion 160B that extends so as to cover the cleaning pad 130. As shown in FIG. 3, the cleaning unit 64 further includes an adhesive tape 135 that adheres the cleaning pad 130 to the plate 160. The plate 160 supports the cleaning pad 130 by attaching the cleaning pad 130 to the support portion 160A by the adhesive tape 135.

[0059] The cleaning pad 130 is located between the second cleaning roller 120 and the support portion 160A of the plate 160 in the second direction. The second direction is a direction intersecting the first direction. In this embodiment, the second direction is perpendicular to the first direction. The adhesive tape 135 is located between the cleaning pad 130 and the support portion 160A of the plate 160 in the second direction.

[0060] 7 and 8, the support portion 160A of the plate 160 has a first opening 161, a second opening 162, a third opening 163, and a fourth opening 164. The drum cartridge 6 further includes a first screw 191 for fixing the plate 160 to the second bearing B2, and a second screw 192 for fixing the plate 160 to the fourth bearing B4.

[0061] 7, the first opening 161 and the third opening 163 are located at one end of the support portion 160A in the first direction. The first opening 161 and the third opening 163 are holes penetrating in the second direction. The first opening 161 is a hole through which the first screw 191 passes. The third opening 163 is a hole into which a boss 186 of the second bearing B2, which will be described later, fits. The first opening 161 is located at a position farther from the extension portion 160B than the third opening 163.

[0062] As shown in FIG. 8, the second opening 162 and the fourth opening 164 are located at the other end of the support portion 160A in the first direction. The second opening 162 and the fourth opening 164 are notches that penetrate in the second direction and open toward the other end side (the front side in FIG. 8) of the support portion 160A in the first direction. The second opening 162 is a notch through which the second screw 192 passes. In this embodiment, the shape of the second screw 192 is the same as the shape of the first screw 191. Also, the size of the second screw 192 is the same as the size of the first screw 191. The fourth opening 164 is a notch into which the boss 186 of the fourth bearing B4 fits. The second opening 162 is located at a position farther from the extension portion 160B than the fourth opening 164.

[0063] Since the second opening 162 and the fourth opening 164 are notches that open in the first direction, it is possible to absorb dimensional errors in the first direction between the first opening 161 and the second opening 162 and between the third opening 163 and the fourth opening 164. Also, it is possible to absorb linear expansion of the plate 160 in the first direction.

[0064] 7 and 8, the first bearing B1 and the third bearing B3 rotatably support the first cleaning roller 110 and the second cleaning roller 120. More specifically, the first bearing B1 rotatably supports one end of the first cleaning roller 110 and the second cleaning roller 120 in the first direction. Furthermore, the third bearing B3 rotatably supports the other end of the first cleaning roller 110 and the second cleaning roller 120 in the first direction.

[0065] In this embodiment, the shape of the third bearing B3 is the same as that of the first bearing B1. Also, the size of the third bearing B3 is the same as that of the first bearing B1. That is, the first bearing B1 and the third bearing B3 are common parts. Below, the first bearing B1 will be described in detail, and for the third bearing B3, the same components as those of the first bearing B1 will be assigned the same reference numerals, and differences from the first bearing B1 will be described.

[0066] 9(a), the first bearing B1 has a shape symmetrical with respect to a plane PL including the first axis A1 and the second axis A2. The first bearing B1 has a first bearing portion 171, a second bearing portion 172, a connecting portion 173, a first rib 174, a second rib 175, a first protrusion 176, and a second protrusion 177.

[0067] The first bearing portion 171 rotatably supports the first shaft 111 of the first cleaning roller 110. The first bearing portion 171 has a first hole 171A penetrating in the first direction. One end portion 111A (see FIG. 7) of the first shaft 111 in the first direction fits into the first hole 171A of the first bearing B1. The first bearing portion 171 of the first bearing B1 rotatably supports the one end portion 111A of the first shaft 111.

[0068] The second bearing portion 172 rotatably supports the second shaft 121 of the second cleaning roller 120. The second bearing portion 172 has a second hole 172A penetrating in the first direction. One end portion 121A (see FIG. 7) of the second shaft 121 in the first direction fits into the second hole 172A of the first bearing B1. The second bearing portion 172 of the first bearing B1 rotatably supports the one end portion 121A of the second shaft 121.

[0069] Here, as shown in FIG. 8, the first hole 171A of the third bearing B3 is an example of a "fourth hole". The other end 111B of the first shaft 111 in the first direction fits into the first hole 171A of the third bearing B3. The first bearing portion 171 of the third bearing B3 rotatably supports the other end 111B of the first shaft 111. The second hole 172A of the third bearing B3 is an example of a "fifth hole". The other end 121B of the second shaft 121 in the first direction fits into the second hole 172A of the third bearing B3. The second bearing portion 172 of the third bearing B3 rotatably supports the other end 121B of the second shaft 121.

[0070] 9(a), the connecting portion 173 connects the first bearing portion 171 and the second bearing portion 172. The connecting portion 173 extends along the plane PL.

[0071] The first rib 174 and the second rib 175 protrude from the first bearing portion 171 in the radial direction of the first shaft 111 of the first cleaning roller 110. The first rib 174 and the second rib 175 are plate-shaped. The second rib 175 is located away from the first rib 174 in the circumferential direction of the first shaft 111. In detail, the second rib 175 is located at a position where the connecting portion 173 is sandwiched between the first rib 174 and the second rib 175 in the radial direction of the first shaft 111. In other words, the connecting portion 173 is located between the first rib 174 and the second rib 175 in the circumferential direction of the first shaft 111.

[0072] The first protrusion 176 and the second protrusion 177 protrude from the first bearing portion 171 in the radial direction of the first shaft 111 of the first cleaning roller 110. The first protrusion 176 protrudes outward in the first direction from the first rib 174. The second protrusion 177 protrudes outward in the first direction from the second rib 175. The second protrusion 177 is located away from the first protrusion 176 in the circumferential direction of the first shaft 111. In detail, the second protrusion 177 is located at a position where the connecting portion 173 is sandwiched between the first protrusion 176 and the second protrusion 177 in the radial direction of the first shaft 111. In other words, the connecting portion 173 is located between the first protrusion 176 and the second protrusion 177 in the circumferential direction of the first shaft 111.

[0073] 7 and 8, the second bearing B2 and the fourth bearing B4 rotatably support the second cleaning roller 120. More specifically, the second bearing B2 rotatably supports one end of the second cleaning roller 120 in the first direction. Furthermore, the fourth bearing B4 rotatably supports the other end of the second cleaning roller 120 in the first direction. Furthermore, a plate 160 that supports the cleaning pad 130 is fixed to the second bearing B2 and the fourth bearing B4.

[0074] In this embodiment, the shape of the fourth bearing B4 is the same as that of the second bearing B2. Also, the size of the fourth bearing B4 is the same as that of the second bearing B2. That is, the second bearing B2 and the fourth bearing B4 are common parts. Below, the second bearing B2 will be described in detail, and for the fourth bearing B4, the same components as those of the second bearing B2 will be given the same reference numerals, and differences from the first bearing B1 will be described.

[0075] The second bearing B2 has a shape symmetrical with respect to the center of the second bearing B2 in the first direction. As shown in Fig. 9(b), the second bearing B2 has a third bearing portion 181, a plate fixing portion 182, a seat portion 183, a first convex portion 184, a second convex portion 185, a boss 186, a third rib 187, and a fourth rib 188.

[0076] The third bearing portion 181 rotatably supports the second shaft 121 of the second cleaning roller 120. The third bearing portion 181 has a third hole 181A penetrating in the first direction. One end portion 121A of the second shaft 121 in the first direction (see FIG. 7) fits into the third hole 181A of the second bearing B2. The third bearing portion 181 of the second bearing B2 rotatably supports the one end portion 121A of the second shaft 121.

[0077] 8, the third hole 181A of the fourth bearing B4 is an example of the "sixth hole". The other end 121B of the second shaft 121 in the first direction is fitted into the third hole 181A of the fourth bearing B4. The third bearing portion 181 of the fourth bearing B4 rotatably supports the other end 121B of the second shaft 121.

[0078] As shown in Fig. 10, the plate 160 is fixed to the plate fixing part 182. The plate fixing part 182 is cylindrical with a bottom. The plate fixing part 182 has a screw hole 182A. The screw hole 182A of the second bearing B2 is a hole into which the first screw 191 is fixed. The screw hole 182A of the fourth bearing B4 (see Fig. 8) is a hole into which the second screw 192 is fixed. Note that the screw hole 182A may be a hole having a thread groove on the inner circumferential surface in advance, or may be a hole into which a thread groove is created when the screws 191, 192 are fixed.

[0079] When the plate 160 is fixed to the second bearing B2, the seating portion 183 comes into contact with the support portion 160A together with the plate fixing portion 182. The seating portion 183 is located between the second shaft 121 of the second cleaning roller 120 and the support portion 160A of the plate 160 in the second direction.

[0080] The first convex portion 184 and the second convex portion 185 protrude from the third bearing portion 181 in the radial direction of the second shaft 121 of the second cleaning roller 120. The first convex portion 184 and the second convex portion 185 are plate-shaped. The second convex portion 185 is located away from the first convex portion 184 in the circumferential direction of the second shaft 121. In this embodiment, the angle between the direction in which the first convex portion 184 protrudes from the third bearing portion 181 and the direction in which the second convex portion 185 protrudes from the third bearing portion 181 is approximately 90 degrees.

[0081] As shown in FIG. 9(c), the first bearing B1 further has a first recess 174A and a second recess 175A. The first recess 174A is a recess into which the first protrusion 184 fits, and is formed in the first rib 174. The second recess 175A is a recess into which the second protrusion 185 fits, and is formed in the second rib 175. The thickness in the first direction of the portion of the first rib 174 where the first recess 174A is formed is thinner than the thickness in the first direction of the portion of the first rib 174 where the first recess 174A is not formed. The thickness in the first direction of the portion of the second rib 175 where the second recess 175A is formed is thinner than the thickness in the first direction of the portion of the second rib 175 where the second recess 175A is not formed. The recesses 174A and 175A have a shape recessed inward in the first direction.

[0082] The first convex portion 184 is fitted into the first concave portion 174A in the direction from the second axis A2 toward the first axis A1. The second convex portion 185 is fitted into the second concave portion 175A in the direction from the second axis A2 toward the first axis A1. Then, after fitting the convex portions 184, 185 into the concave portions 174A, 175A and assembling the second bearing B2 to the first bearing B1, the second shaft 121 of the second cleaning roller 120 is fitted into the third hole 181A (see FIG. 9(b)) of the third bearing portion 181 and the second hole 172A of the second bearing portion 172 from the inside in the first direction.

[0083] 10, the boss 186 protrudes from the seat portion 183 toward the support portion 160A of the plate 160. The boss 186 is generally cylindrical. The boss 186 of the second bearing B2 fits into the third opening 163 of the plate 160. The boss 186 of the fourth bearing B4 (see FIG. 8) fits into the fourth opening 164 of the plate 160. The boss 186 also fits into a boss hole 154B of the housing 150, which will be described later.

[0084] The third rib 187 and the fourth rib 188 protrude from the plate fixing portion 182 in the radial direction of the plate fixing portion 182. The third rib 187 and the fourth rib 188 are plate-shaped. The fourth rib 188 is located away from the third rib 187 in the circumferential direction of the plate fixing portion 182. More specifically, the third rib 187 extends in the radial direction of the plate fixing portion 182 in the same direction as the seat portion 183 extends from the plate fixing portion 182. Moreover, the fourth rib 188 extends in the opposite direction to the third rib 187 in the radial direction of the plate fixing portion 182.

[0085] 6, the housing 150 of the cleaning unit 64 further has a fixing portion 154, a first groove 155, and a second groove 156. The fixing portion 154, the first groove 155, and the second groove 156 are formed at both ends of the housing 150 in the first direction, respectively.

[0086] The plate 160 and the bearings B2, B4 are fixed to the fixed portion 154. The fixed portion 154 has a screw hole 154A and a boss hole 154B. The screw hole 154A and the boss hole 154B are holes that penetrate in the second direction. The screw hole 154A is a hole through which the screws 191, 192 pass. The boss hole 154B is a hole into which the boss 186 of the bearings B2, B4 fits. The screw hole 154A is located closer to the tip of the fixed portion 154 than the boss hole 154B.

[0087] 10, when fixing the second housing 153, the plate 160, and the second bearing B2 of the housing 150, first, the boss 186 of the second bearing B2 is inserted from one side in the second direction into the third opening 163 of the support part 160A and the boss hole 154B of the fixed part 154. Then, the first screw 191 is passed through the screw hole 154A of the fixed part 154 and the first opening 161 of the support part 160A from the other side in the second direction toward the first cleaning roller 110, and fixed into the screw hole 182A of the second bearing B2. The same is true when fixing the second housing 153, the plate 160, and the fourth bearing B4.

[0088] 6, the first groove 155 accommodates the first rib 174 of the bearings B1 and B3 and the third rib 187 of the bearings B2 and B4. The first groove 155 is located in the second housing 153. In detail, the first groove 155 is formed by an outer wall 155A located on the outer side of the ribs 174 and 187 in the first direction, and an inner wall 155B located on the inner side of the ribs 174 and 187 in the first direction.

[0089] The second groove 156 accommodates the second rib 175 of the bearings B1, B3 and the fourth rib 188 of the bearings B2, B4. The second groove 156 is located in the first housing 152. In detail, the second groove 156 is formed by an outer wall 156A located on the outer side of the ribs 175, 188 in the first direction, and an inner wall 156B located on the inner side of the ribs 175, 188 in the first direction.

[0090] In the bearings B1 to B4, the first housing 152 and the second housing 153 are assembled, the ribs 174, 187 are housed in the first groove 155, and the ribs 175, 188 are housed in the second groove 156. More specifically, the ribs 174, 187 are placed between the outer wall 155A and the inner wall 155B, and the ribs 175, 188 are placed between the outer wall 156A and the inner wall 156B. This restricts the movement of the bearings B1 to B4 in the first direction.

[0091] 11, the first clearance C1 is a clearance between the first cleaning roller 110 and the second housing 153. In detail, the first clearance C1 is a clearance between the outer circumferential surface of the first roller body 112 of the first cleaning roller 110 and the second housing 153.

[0092] The second clearance C2 is the clearance between the first bearing B1 and the second housing 153. More specifically, the second clearance C2 is the clearance between the first protrusion 176 of the first bearing B1 and the second housing 153. Although not shown, the clearance between the third bearing B3 and the second housing 153 is also the second clearance C2. More specifically, the clearance between the first protrusion 176 of the third bearing B3 and the second housing 153 is also the second clearance C2.

[0093] The third clearance C3 is a clearance between the first bearing B1 and the first cleaning roller 110. More specifically, the third clearance C3 is a clearance between an inner peripheral surface of the first hole 171A of the first bearing B1 and an outer peripheral surface of the first shaft 111 of the first cleaning roller 110. Although not shown, the clearance between the third bearing B3 and the first cleaning roller 110 is also the third clearance C3. More specifically, the clearance between the inner peripheral surface of the first hole 171A of the third bearing B3 and the outer peripheral surface of the first shaft 111 is also the third clearance C3.

[0094] The fourth clearance C4 is a clearance between the plate 160 and the second housing 153. In detail, the fourth clearance C4 is a clearance between the extension portion 160B of the plate 160 and the second housing 153.

[0095] In this embodiment, the sum of the second clearance C2 and the third clearance C3 is smaller than the first clearance C1. This makes it possible to prevent the first roller body 112 of the first cleaning roller 110 from coming into contact with the second housing 153. In detail, even if the first cleaning roller 110 moves relative to the housing 150, the second clearance C2 is clogged and the first shaft 111 of the first cleaning roller 110 comes into contact with the bearings B1 and B3, or the third clearance C3 is clogged and the first protrusion 176 of the bearings B1 and B3 comes into contact with the second housing 153, thereby making it possible to prevent the first roller body 112 of the first cleaning roller 110 from coming into contact with the second housing 153.

[0096] Moreover, the fourth clearance C4 is smaller than the first clearance C1. This makes it possible to prevent the second housing 153 from coming into contact with the first roller body 112 of the first cleaning roller 110. In particular, even if a force is applied to the center of the second housing 153 in the first direction and the second housing 153 is bent, the second housing 153 comes into contact with the extension portion 160B of the plate 160 made of metal, thereby making it possible to prevent the second housing 153 from coming into contact with the first roller body 112 of the first cleaning roller 110.

[0097] In this embodiment, the third clearance C3 is smaller than the second clearance C2. The second clearance C2 is also smaller than the fourth clearance C4. That is, the first clearance C1, the second clearance C2, the third clearance C3, and the fourth clearance C4 are smaller in this order: first clearance C1, fourth clearance C4, second clearance C2, third clearance C3.

[0098] 12, the printable area AP is an area where printing can be performed on the sheet S by the image forming apparatus 1. The printable length LP is the length of the printable area AP in the first direction. The center line CL indicates the center position of the printable area AP in the first direction.

[0099] The photosensitive layer coated area AC is an area of ​​the photosensitive drum 61 where the photosensitive layer 61C is coated. The guaranteed area AC1 is an area of ​​the photosensitive layer coated area AC where the thickness of the photosensitive layer 61C is equal to or greater than a predetermined value. The guaranteed area AC1 is located between both ends of the photosensitive layer coated area AC in the first direction. The coated area length LC is the length of the photosensitive layer coated area AC in the first direction. The coated area length LC is longer than the printable length LP. The guaranteed area length LC1 is the length of the guaranteed area AC1 in the first direction. The guaranteed area length LC1 is longer than the printable length LP. The guaranteed area length LC1 is shorter than the coated area length LC.

[0100] The first roller length L110 is the length of the first roller body 112 of the first cleaning roller 110 in the first direction. The first roller length L110 is longer than the printable length LP. The first roller length L110 is longer than the guaranteed area length LC1. The first roller length L110 is shorter than the application area length LC.

[0101] The second roller length L120 is the length of the second roller body 122 of the second cleaning roller 120 in the first direction. The second roller length L120 is longer than the printable length LP. The second roller length L120 is longer than the guaranteed area length LC1. The second roller length L120 is shorter than the application area length LC. The second roller length L120 is longer than the first roller length L110. The first roller body 112 of the first cleaning roller 110 is located within the width of the second roller body 122 of the second cleaning roller 120 in the first direction.

[0102] The pad length L130 is the length of the cleaning pad 130 in the first direction. The pad length L130 is longer than the printable length LP. The pad length L130 is longer than the guaranteed area length LC1. The pad length L130 is shorter than the application area length LC. The pad length L130 is longer than the first roller length L110. The pad length L130 is approximately the same as the second roller length L120. In the first direction, the cleaning pad 130 is located at approximately the same position as the second roller body 122 of the second cleaning roller 120.

[0103] According to the drum cartridge 6 of the present embodiment described above, the first bearing B1 can improve the positional accuracy of the first cleaning roller 110 and the second cleaning roller 120. Furthermore, the second bearing B2 supporting the second cleaning roller 120 and the plate 160 supporting the cleaning pad 130 are fixed by the first screw 191, so that the positional accuracy of the second cleaning roller 120 and the cleaning pad 130 can be improved. This can improve the cleaning performance of the cleaning unit 64.

[0104] Furthermore, since the third bearing B3 and the fourth bearing B4 are further provided at the other end in the first direction, the first bearing B1 and the third bearing B3 can further improve the positional accuracy of the first cleaning roller 110 and the second cleaning roller 120. Furthermore, the second bearing B2 and the fourth bearing B4 that support the second cleaning roller 120 and the plate 160 are fixed by the first screw 191 and the second screw 192, so that the positional accuracy of the second cleaning roller 120 and the cleaning pad 130 can further be improved.

[0105] In addition, since the cleaning pad 130 is located between the second cleaning roller 120 and the plate 160 in the second direction, the reaction force that the cleaning pad 130 receives from the second cleaning roller 120 can be received by the plate 160. This makes it possible to suppress the cleaning pad 130 from moving away from the second cleaning roller 120.

[0106] Furthermore, in the second direction, the first screw 191 and the second screw 192 can be tightened in a direction that presses the cleaning pad 130 against the second cleaning roller 120. This makes it possible to prevent the cleaning pad 130, which receives a reaction force from the second cleaning roller 120, from moving away from the second cleaning roller 120 and to bring the cleaning pad 130 into firm contact with the circumferential surface of the second cleaning roller 120.

[0107] In addition, since the adhesive tape 135 is located between the cleaning pad 130 and the plate 160 in the second direction, the cleaning pad 130 is pressed against the plate 160 via the adhesive tape 135 by the reaction force that the cleaning pad 130 receives from the second cleaning roller 120. This makes it difficult for the cleaning pad 130 to peel off from the plate 160 when adhered with the adhesive tape 135.

[0108] In addition, since the cleaning pad 130 has corners 131 that come into contact with the peripheral surface of the second cleaning roller 120, the cleaning pad 130 can come into line contact with the peripheral surface of the second cleaning roller 120. This allows the silicone rubber cleaning pad 130 to firmly scrape off any deposits on the peripheral surface of the second cleaning roller 120, specifically, paper powder.

[0109] Furthermore, when manufacturing the drum cartridge 6, specifically, when assembling the first bearing B1 and the second bearing B2, the first convex portion 184 and the first concave portion 174A, and the second convex portion 185 and the second concave portion 175A are fitted together, respectively, so that the relative rotation between the first bearing B1 and the second bearing B2 is suppressed and the positions of the first bearing B1 and the second bearing B2 can be provisionally determined. This makes it possible to easily assemble the drum cartridge 6. The third bearing B3 is a part common to the first bearing B1, and the fourth bearing B4 is a part common to the second bearing B2, so the same applies when assembling the third bearing B3 and the fourth bearing B4.

[0110] In addition, because the drum frame 65 has the frame opening 65A that exposes a portion of the housing 150 of the cleaning unit 64, the size of the housing 150 can be made larger than when the entire housing is located inside the drum frame. This allows the capacity of the portion of the housing 150 that stores paper dust, specifically, the capacity of the paper dust storage section 151, to be increased.

[0111] In addition, since the drum frame 65 has multiple frame openings 65A spaced apart in the first direction, the capacity of the paper powder storage section 151 can be increased while ensuring the rigidity of the drum frame 65, compared to, for example, a case in which there is one large frame opening that is long in the first direction.

[0112] In addition, since the shape of the fourth bearing B4 is the same as the shape of the second bearing B2, the second bearing B2 and the fourth bearing B4 are common parts, so that the number of types of parts required for manufacturing the drum cartridge 6 can be reduced.

[0113] In addition, since the shape of the third bearing B3 is the same as the shape of the first bearing B1, the first bearing B1 and the third bearing B3 are common parts, so that the number of types of parts required for manufacturing the drum cartridge 6 can be reduced.

[0114] Although the embodiment has been described above, the drum unit is not limited to the above-described embodiment, and can be modified as appropriate as exemplified below.

[0115] In the above embodiment, the second bearing B2 has the first convex portion 184 and the second convex portion 185 that protrude in the radial direction of the second shaft 121 and are spaced apart in the circumferential direction of the second shaft 121, and the first bearing B1 has the first concave portion 174A and the second concave portion 175A, but this is not limited to the above. For example, the first bearing may have the first convex portion and the second convex portion that protrude in the radial direction of the first shaft and are spaced apart in the circumferential direction of the first shaft, and the second bearing may have the first concave portion and the second concave portion. Also, the first convex portion, the second convex portion, the first concave portion, and the second concave portion may not be included.

[0116] In the above embodiment, the shape of the fourth bearing B4 and the shape of the second bearing B2 are the same, but this is not limited thereto, and the shape of the fourth bearing and the shape of the second bearing may be different. That is, the second bearing and the fourth bearing do not have to be common parts. Also, in the above embodiment, the shape of the third bearing B3 and the shape of the first bearing B1 are the same, but this is not limited thereto, and the shape of the third bearing and the shape of the first bearing may be different. That is, the first bearing and the third bearing do not have to be common parts.

[0117] In the above embodiment, the first roller length L110, the second roller length L120, and the pad length L130 are longer than the guaranteed area length LC1 as shown in Fig. 12, but are not limited to this. For example, the first roller length, the second roller length, and the pad length may be shorter than the guaranteed area length LC1.

[0118] In the above embodiment, the first roller length L110, the second roller length L120, and the pad length L130 are shorter than the application area length LC as shown in Fig. 12, but are not limited to this. For example, the first roller length, the second roller length, and the pad length may be longer than the application area length LC.

[0119] In the above embodiment, the entire cleaning pad 130 is made of silicone rubber, but the present invention is not limited to this. For example, the cleaning pad may be made of silicone rubber only in the portion that contacts the circumferential surface of the second cleaning roller. The cleaning pad may also be made of sponge or the like.

[0120] In the above-described embodiment, the cleaning pad 130 is exemplified as the cleaning member, but the present invention is not limited thereto. For example, as shown in FIG. 13, the cleaning member 230 may be an auger. More specifically, the cleaning member 230 may be an auger having a shaft 231 and a cleaning portion 232. The shaft 231 is rotatably supported by a plate (not shown). The cleaning portion 232 is located around the shaft 231 and has a spiral shape. The cleaning portion 232 is made of a sponge or the like. The cleaning member 230 cleans paper powder from the peripheral surface of the second cleaning roller 120 while rotating.

[0121] According to the cleaning pad 130 of the above-mentioned embodiment, cleaning can be performed without compacting the paper dust. Also, according to the cleaning member 230 as shown in Fig. 13, the paper dust can be moved in the first direction without remaining in the same position in the first direction, so that cleaning can be performed without compacting the paper dust.

[0122] In the above embodiment, the drum frame 65 has a configuration having a plurality of frame openings 65A that expose a part of the housing 150, but the present invention is not limited to this. For example, the drum frame may have only one frame opening that exposes a part of the housing. Also, the drum frame may not have a frame opening that exposes a part of the housing, and the drum unit may have a configuration in which the entire housing is located inside the drum frame.

[0123] In the above embodiment, the first cleaning roller 110, the second cleaning roller 120, and the cleaning pad 130 (cleaning members) are configured to clean paper dust, but the present invention is not limited to this. For example, the first cleaning roller, the second cleaning roller, and the cleaning members may be configured to clean other than paper dust, such as toner remaining on the circumferential surface of the photosensitive drum that has not been transferred thereto.

[0124] The elements described in the above embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0125] 6 Drum Cartridge 61 Photosensitive drum 61A Drum shaft 110 First cleaning roller 111 1st Shaft 111A One end 120 Second cleaning roller 121 Second Shaft 121A One end 130 Cleaning Pad 160 Plates 171A 1st hole 172A 2nd hole 181A 3rd hole 191 First screw A1 First axis A2 2nd axis B1 First bearing B2 Second bearing

Claims

1. a photosensitive drum rotatable about a drum axis extending in a first direction; a first cleaning roller having a first shaft rotatable about a first axis extending in the first direction, the first cleaning roller being in contact with a peripheral surface of the photosensitive drum; a second cleaning roller having a second shaft rotatable about a second axis extending in the first direction, the second cleaning roller being in contact with a peripheral surface of the first cleaning roller; a first bearing having a first hole into which one end of the first shaft in the first direction is fitted and a second hole into which one end of the second shaft in the first direction is fitted; a second bearing having a third hole into which the one end of the second shaft in the first direction is fitted; a cleaning member that contacts the circumferential surface of the second cleaning roller; a plate supporting the cleaning member; a first screw for fixing the plate to the second bearing.

2. 2. The drum unit according to claim 1, wherein the cleaning member is a cleaning pad.

3. 3. The drum unit according to claim 2, wherein the cleaning pad is positioned between the second cleaning roller and the plate in a second direction intersecting the first direction.

4. the plate has an opening through which the first screw passes and which penetrates in the second direction; 4. The drum unit according to claim 3, wherein the second bearing has a screw hole into which the first screw is fixed.

5. 5. The drum unit according to claim 3, wherein the second direction is perpendicular to the first direction.

6. 6. The drum unit according to claim 3, further comprising an adhesive tape for adhering the cleaning pad to the plate, the adhesive tape being positioned between the cleaning pad and the plate in the second direction.

7. The first cleaning roller cleans paper dust from the peripheral surface of the photosensitive drum, The second cleaning roller cleans paper dust from the peripheral surface of the first cleaning roller, 7. The drum unit according to claim 2, wherein the cleaning pad cleans paper dust off the peripheral surface of the second cleaning roller.

8. 8. The drum unit according to claim 2, wherein the cleaning pad is made of silicone rubber.

9. 9. The drum unit according to claim 8, wherein the cleaning pad has a corner portion that comes into contact with the peripheral surface of the second cleaning roller.

10. 10. The drum unit according to claim 9, wherein the angle of the corner is equal to or greater than 10 degrees and equal to or less than 170 degrees.

11. The second bearing is a first protrusion protruding in a radial direction of the second shaft; a second protruding portion protruding in a radial direction of the second shaft and positioned away from the first protruding portion in a circumferential direction of the second shaft, The first bearing is a first recess into which the first protrusion fits; 11. The drum unit according to claim 1, further comprising a second recess into which the second protrusion fits.

12. a housing that contains paper dust collected from the peripheral surface of the photosensitive drum by the first cleaning roller; a drum frame supporting the photosensitive drum and the housing, 12. The drum unit according to claim 1, wherein the drum frame has a frame opening through which a part of the housing is exposed when the housing is supported by the drum frame.

13. The drum frame has a plurality of frame openings, The drum unit according to claim 12, wherein the frame openings are spaced apart from one another in the first direction.

14. a third bearing having a fourth hole into which the other end of the first shaft in the first direction is fitted and a fifth hole into which the other end of the second shaft in the first direction is fitted; a fourth bearing having a sixth hole into which the other end of the second shaft in the first direction is fitted; The drum unit according to claim 1 , further comprising: a second screw that fixes the plate to the fourth bearing.

15. 15. The drum unit according to claim 14, wherein the fourth bearing has a shape identical to that of the second bearing.

16. 16. The drum unit according to claim 14, wherein the third bearing has a shape identical to that of the first bearing.

Images