Drum unit and image forming device

Abstract

An image forming device includes a housing, a toner cartridge, and a drum unit. The drum unit is movable through an opening between a storage position in which the drum unit is positioned within the housing and a pulled-out position in which the drum unit is pulled out of the housing. The drum unit includes a photosensitive drum and a developer unit. The photosensitive drum is rotatable about a first axis extending in a second direction. The developer unit includes a magnetic roller, a developer container, a first auger, and a second auger. The magnetic roller is positioned between the toner cartridge and the photosensitive drum. The magnetic roller faces a surface of the photosensitive drum. The developer container is formed with an inlet for allowing toner to be replenished from the toner cartridge. The first auger is positioned within the developer container. The second auger is positioned within the developer container.

Description

Technical Field

[0001] The present disclosure relates to a drum unit including a conveying member configured to convey toner together with a carrier, and an image forming apparatus to which and from which the drum unit can be attached and detached. Background Art

[0002] Conventionally, an image forming apparatus described in Patent Document 1 includes a housing, a drum unit, and a toner cartridge. The drum unit includes a developer container and a carrier for storing toner therein. In addition to the developer container, the image forming apparatus also includes a toner replenishing device between the toner cartridge and the developer container. The toner replenishing device is configured to temporarily store and agitate toner supplied from the toner cartridge in order to replenish the toner into the developer container.

[0003] [Citation List]

[0004] [Patent Document]

[0005] [PTL1]

[0006] Japanese Patent Application Publication No. 2006-171105 Summary of the Invention

[0007] [Technical Issues]

[0008] In the above-mentioned prior art, in order to replenish the toner in the toner cartridge into the developer container, a toner replenishing device is required in addition to the toner cartridge, the developer container and the drum unit. However, providing the toner replenishing device in the image forming apparatus may increase the size of the drum unit and the image forming apparatus.

[0009] In view of the foregoing circumstances, an object of the present disclosure is to provide an image forming apparatus and a drum unit capable of suppressing an increase in size of the image forming apparatus and the drum unit.

[0010] [Solution to the problem]

[0011] To achieve this objective, according to a first aspect, the present disclosure provides an image forming device comprising a housing, a toner cartridge, and a drum unit. The housing has an opening and a front cover, the front cover being movable between an open position in which the front cover opens the opening and a closed position in which the front cover closes the opening. The toner cartridge is configured to accommodate toner therein. The toner cartridge is attachable to the drum unit. When the toner cartridge is attached to the drum unit, the drum unit is movable relative to the housing in a first direction. The drum unit is movable through the opening between a position in which the drum unit is positioned within the housing and a position in which the drum unit is withdrawn from the housing. The drum unit includes a photosensitive drum and a developing unit. The photosensitive drum is rotatable about a first axis extending in a second direction. The developing unit is positioned between the toner cartridge and the photosensitive drum. The developing unit includes a magnetic roller, a developer container, a first auger, and a second auger. The magnetic roller is positioned between the toner cartridge and the photosensitive drum and is rotatable about a second axis extending in the second direction. The magnetic roller faces the surface of the photosensitive drum. The developer container is configured to accommodate a carrier. The developer container is formed with an inlet for allowing toner to be replenished from a toner cartridge. A first auger is positioned in the developer container and is rotatable about a third axis extending in the second direction. The first auger is configured to circulate toner and a carrier in the developer container. A second auger is positioned in the developer container and is rotatable about a fourth axis extending in the second direction. The second auger is configured to transport the toner and the carrier to a magnetic roller.

[0012] With this structure, the toner cartridge can be attached to the drum unit, and the toner is directly replenished to the developing container from the toner cartridge attached to the drum unit. Therefore, the conventional toner replenishing device can be omitted, and thus the size increase of the drum unit and the color printer can be suppressed.

[0013] According to a second aspect, in the image forming apparatus according to the first aspect, the first direction intersects with the second direction.

[0014] According to a third aspect, in the image forming apparatus according to the first aspect or the second aspect, the inlet is positioned opposite to the magnetic roller with respect to the first auger and the second auger.

[0015] According to a fourth aspect, in the image forming apparatus according to any one of the first to third aspects, the photosensitive drum includes an array of a plurality of photosensitive drums arranged in a first direction, and the developing unit includes an array of a plurality of developing units arranged in the first direction.

[0016] According to a fifth aspect, in the image forming apparatus according to any one of the first to fourth aspects, the image forming apparatus further includes a transfer member configured to transfer the toner image on the photosensitive drum to the sheet.

[0017] According to a sixth aspect, in the image forming apparatus according to any one of the first to fifth aspects, the drum unit further includes a sheet guide configured to guide the sheet toward the photosensitive drum.

[0018] According to a seventh aspect, in the image forming apparatus according to any one of the first to sixth aspects, the drum unit further includes a cleaning roller configured to clean the photosensitive drum.

[0019] According to an eighth aspect, in the image forming apparatus according to any one of the first to seventh aspects, the inlet is positioned above the first auger and the second auger, and the second axis is positioned below the first auger and the second auger.

[0020] According to a ninth aspect, in the image forming apparatus according to the eighth aspect, the developing unit further includes a layer thickness regulating member configured to regulate a thickness of the toner layer formed on the magnetic roller. The layer thickness regulating member does not contact the magnetic roller.

[0021] According to a tenth aspect, in the image forming apparatus according to the ninth aspect, the layer thickness regulating member is positioned below the first auger and the second auger.

[0022] According to an eleventh aspect, in the image forming apparatus according to any one of the first to tenth aspects, the magnetic roller is positioned away from the surface of the photosensitive drum.

[0023] According to a twelfth aspect, in the image forming apparatus according to any one of the first to eleventh aspects, the first auger is positioned closer to the inlet than the second auger is to the inlet.

[0024] According to a thirteenth aspect, in the image forming apparatus according to any one of the first to twelfth aspects, the first auger is configured to convey toner replenished from the inlet to the second auger. The second auger is configured to supply the toner conveyed by the first auger to the magnetic roller. The magnetic roller is configured to supply the toner supplied from the second auger to the photosensitive drum.

[0025] According to a fourteenth aspect, in the image forming apparatus according to any one of the first to thirteenth aspects, the drum unit further includes a first side wall, a second side wall, and a cylindrical member. The first side wall is formed with a first hole, the first hole allowing one end portion of the developing unit in the second direction to be inserted into the first hole so that the one end portion is supported by the first side wall. The second side wall is formed with a second hole, the second side wall facing the first side wall in the second direction. The cylindrical member is inserted into the second hole, the cylindrical member having an opening, and the other end portion of the developing unit in the second direction is inserted into the opening.

[0026] According to a fifteenth aspect, in the image forming apparatus according to the fourteenth aspect, one end portion of the developing unit in the second direction includes a boss and a protrusion. The boss extends in the second direction and is inserted into the first hole. The protrusion protrudes from the boss in a direction perpendicular to the second direction. The protrusion contacts a surface of the first side wall that faces the second side wall to fix the position of the developing unit in the second direction.

[0027] According to a sixteenth aspect, in the image forming apparatus according to the fifteenth aspect, the cylindrical member includes a cylindrical portion and a flange. The cylindrical portion is inserted into the second hole and has an outer peripheral surface. The flange protrudes from the outer peripheral surface. The flange is positioned opposite the first side wall relative to the second side wall.

[0028] With this structure, since the flange is positioned opposite to the first side wall relative to the second side wall, the release of the cylindrical member from the second side wall can be restricted.

[0029] According to a seventeenth aspect, in the image forming apparatus according to the sixteenth aspect, the drum unit further includes a third side wall positioned opposite to the first side wall relative to the second side wall, and the flange is positioned between the second side wall and the third side wall.

[0030] With this structure, since the flange is sandwiched between the second side wall and the third side wall, the release of the cylindrical member from the second side wall W2 can be further restricted.

[0031] According to an eighteenth aspect, in the image forming apparatus according to the seventeenth aspect, the drum unit further includes a fourth side wall positioned opposite the second side wall relative to the first side wall. The first side wall and the second side wall are positioned between the third side wall and the fourth side wall in the second direction.

[0032] With this structure, since the first side wall and the second side wall are positioned between the third side wall and the fourth side wall, the first side wall and the second side wall can be protected by the third side wall and the fourth side wall.

[0033] According to a nineteenth aspect, in the image forming apparatus according to any one of the first aspect to the eighteenth aspect, the drum unit further includes a charger configured to charge the photosensitive drum.

[0034] According to a twentieth aspect, in the image forming apparatus according to the nineteenth aspect, the charger is a scorotron charger.

[0035] According to the twenty-first aspect, in the image forming device according to the eighteenth aspect, the present disclosure provides a method for assembling the image forming device, comprising: after inserting the boss into the first hole in the direction from the second side wall to the first side wall, making the protrusion contact with the surface of the first side wall facing the second side wall; after the protrusion contacts the surface of the first side wall facing the second side wall, inserting the cylindrical member into the second hole in the direction from the second side wall to the first side wall so that the other end of the developing unit is inserted into the cylindrical member, and since the cylindrical member is inserted into the second hole, the flange is located at a position opposite to the first side wall relative to the second side wall; attaching the third side wall to the surface of the second side wall, which is opposite to the surface of the second side wall facing the first wall; and attaching the fourth wall to the surface of the first side wall, which is opposite to the surface of the first side wall facing the second wall.

[0036] To achieve this objective, according to a twenty-second aspect, the present disclosure provides a drum unit to which a toner cartridge can be attached. The toner cartridge is configured to accommodate toner therein. When the toner cartridge is attached to the drum unit, the drum unit is movable relative to the housing in a first direction. The drum unit is movable through an opening between a storage position in which the drum unit is positioned in the housing and a withdrawal position in which the drum unit is withdrawn from the housing. The drum unit includes a photosensitive drum and a developer unit. The photosensitive drum is rotatable about a first axis extending in a second direction. The developer unit is positioned between the toner cartridge and the photosensitive drum. The developer unit includes a magnetic roller, a developer container, a first auger, and a second auger. The magnetic roller is positioned between the toner cartridge and the photosensitive drum and is rotatable about a second axis extending in the second direction. The magnetic roller faces the surface of the photosensitive drum. The developer container is configured to accommodate a carrier. The developer container is formed with an inlet for allowing toner to be replenished from the toner cartridge. The first auger is positioned in the developer container and is rotatable about a third axis extending in the second direction. The first auger is configured to circulate the toner and the carrier in the developer container. The second auger is positioned in the developer container and is rotatable about a fourth axis extending in the second direction. The second auger is configured to convey the toner and the carrier to the magnetic roller.

[0037] With this structure, it is possible to suppress an increase in size of the drum unit and the image forming apparatus.

[0038] [Beneficial Effects of the Invention]

[0039] According to the present disclosure, it is possible to suppress an increase in size of the drum unit and the image forming apparatus. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a cross-sectional view of a color printer including a drum unit according to one embodiment of the present disclosure;

[0041] Figure 2 is a cross-sectional view of the drum unit positioned in a pulled-out position;

[0042] Figure 3 is a cross-sectional view of a drum unit with a toner cartridge attached;

[0043] Figure 4A is a perspective view of a developing unit;

[0044] Figure 4B is another perspective view of the developing unit;

[0045] Figure 5 is a cross-sectional view of a developing unit;

[0046] Figure 6 is a perspective view of a drum unit according to an embodiment;

[0047] Figure 7 is an exploded perspective view showing the structure of the other side in the second direction of the drum unit;

[0048] Figure 8 is an exploded perspective view showing the structure of one side of the drum unit in the second direction;

[0049] Figure 9A is a diagram illustrating a method for assembling the drum unit;

[0050] Figure 9B is another diagram illustrating a method for assembling the drum unit; and

[0051] Figure 9C is yet another diagram illustrating a method for assembling the drum unit. DETAILED DESCRIPTION

[0052] Hereinafter, a drum unit according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. Figure 1 The overall structure of a color printer 1 as an example of an image forming apparatus to which a drum unit is applied will be described. The color printer 1 includes a housing 10 , a sheet supply unit 20 , an image forming unit 30 , and a discharge unit 90 .

[0053] The housing 10 has an opening 10A and includes a front cover 11. The front cover 11 is movable between an open position where the front cover 11 opens the opening 10A and a closed position where the front cover 11 closes the opening 10A. Specifically, the front cover 11 is pivotally movable between the open position and the closed position.

[0054] The sheet supply unit 20 includes a supply tray 21 and a sheet feeding mechanism 22. The supply tray 21 is configured to store a stack of sheets S. The sheet feeding mechanism 22 is configured to convey the sheets S from the supply tray 21 to the image forming unit 30. As the sheets S, heavy paper, postcards, and thin paper can be used.

[0055] The image forming unit 30 includes a scanner unit 40 , a process unit U, a transfer unit 70 , and a fixing unit 80 .

[0056] The scanner unit 40 includes a laser emitting portion, a polygon mirror, a lens, and a reflecting mirror, which are not shown.

[0057] The process unit U includes a drum unit 50 and four toner cartridges TC.

[0058] The toner cartridge TC is configured to accommodate therein toner as a non-magnetic material. Figure 3 As shown, four toner cartridges TC are attachable to and detachable from the frame of the drum unit 50. Specifically, each toner cartridge TC is attachable to and detachable from the frame of the drum unit 50 in a direction perpendicular to a second direction (described later). Figure 6 9 , the frame of the drum unit 50 is described.

[0059] The drum unit 50 is movable in the first direction relative to the housing 10 through the opening 10A.

[0060] Specifically, the drum unit 50 is movable in the first direction between an accommodation position at which the drum unit 50 is accommodated in the housing 10 and a pull-out position at which the drum unit 50 is pulled out of the housing 10. Figure 3 As shown, the drum unit 50 includes four photosensitive drums 51, four scorotron chargers 52, four cleaning rollers 53, four developing units 60, and a sheet guide 54. The above-mentioned scanner unit 40 is configured to irradiate the photosensitive drums 51 with laser beams.

[0061] The photosensitive drum 51 is rotatable about a first axis X1 extending in a second direction. The second direction intersects the first direction, and specifically, the second direction is perpendicular to the first direction. The four photosensitive drums 51 are arranged in sequence in the first direction.

[0062] The scorotron charger 52 is configured to charge the photosensitive drum 51. Incidentally, a charging roller may be employed in place of the scorotron charger 52. The cleaning roller 53 is configured to clean the photosensitive drum 51. Incidentally, a cleaning blade may be employed in place of the cleaning roller 53.

[0063] The four developing units 60 are arranged in sequence in the first direction. Each developing unit 60 is positioned between each toner cartridge TC and each photosensitive drum 51. The developing unit 60 includes a magnetic roller 61, a developer container 62, a first auger 63, a second auger 64, and a layer thickness regulating blade 65.

[0064] The magnetic roller 61 is configured to supply toner to the photosensitive drum 51. The magnetic roller 61 includes a magnetic shaft 61A and a magnetic sleeve 61B. The magnetic shaft 61A has alternating magnetic poles arranged in a predetermined pattern along its circumference. The magnetic shaft 61A is a solid cylindrical member embedded with a plurality of permanent magnets. The magnetic shaft 61A is fixed to the developer container 62.

[0065] The magnetic sleeve 61B is a hollow cylindrical member mainly made of non-magnetic metal. The magnetic sleeve 61B is rotatable around the magnetic shaft 61A. The magnetic sleeve 61B holds the toner by the magnetic force of the magnetic shaft 61A.

[0066] The magnetic roller 61 is positioned between the toner cartridge TC and the photosensitive drum 51. The magnetic sleeve 61B is rotatable about a second axis X2 extending in the second direction. The magnetic roller 61 faces the surface of the photosensitive drum 51. The magnetic roller 61 is separated from the surface of the photosensitive drum 51.

[0067] The developer container 62 is configured to accommodate a carrier, which is a magnetic material. Iron powder is an example of a carrier. The developer container 62 has an inlet 62A through which toner is replenished from the toner cartridge TC. The inlet 62A is positioned opposite the magnetic roller 61 relative to the first auger 63 and the second auger 64. The toner cartridge TC is attached to the developer container 62 according to the frame that attaches the toner cartridge TC to the drum unit 50.

[0068] The inlet 62A is positioned above the first auger 63 and the second auger 64. Specifically, the inlet 62A is positioned vertically above the first auger 63. The second axis X2 is positioned below the first auger 63 and the second auger 64. Specifically, the second axis X2 is positioned vertically below the second auger 64.

[0069] A first auger 63 is positioned in the developer container 62. The first auger 63 is rotatable about a third axis X3 extending in the second direction. The first auger 63 and the second auger 64 are aligned with each other in the first direction. The first auger 63 is positioned closer to the inlet 62A than the second auger 64 is to the inlet 62A. The first auger 63 is configured to circulate the toner and carrier in the developer container 62. The first auger 63 is configured to convey the toner replenished from the inlet 62A to the second auger 64.

[0070] The second auger 64 is positioned in the developer container 62. The second auger 64 is rotatable about a fourth axis X4 extending in the second direction. The second auger 64 is configured to convey the toner and carrier in the developer container 62 toward the magnetic roller 61. In other words, the second auger 64 is configured to supply toner to the magnetic roller 61. The second auger 64 is configured to circulate the toner and carrier in the developer container 62.

[0071] The layer thickness regulating blade 65 is configured to regulate the thickness of the toner layer formed on the magnetic roller 61. The layer thickness regulating blade 65 does not contact the magnetic roller 61. The layer thickness regulating blade 65 is positioned below the first auger 63 and the second auger 64. Specifically, the layer thickness regulating blade 65 is positioned vertically below the first auger 63.

[0072] The layer thickness regulating blade 65 is aligned with the magnetic roller 61 in the first direction. The second axis X2 is positioned between the layer thickness regulating blade 65 and the first axis X1 in the first direction.

[0073] The sheet guide 54 is configured to guide the sheet S toward the photosensitive drum 51. The sheet guide 54 is aligned with the photosensitive drum 51 in the first direction. The sheet guide 54 is located on the upstream side of the four photosensitive drums 51 in the sheet S conveying direction.

[0074] The magnet roller 61 positioned most upstream in the sheet conveying direction among the four magnet rollers 61 is positioned between the sheet guide 54 and the second auger 64. Furthermore, each of the four magnet rollers 61 is positioned between the sheet guide 54 and the first and second augers 63, 64 in a third direction perpendicular to the first and second directions. The layer thickness regulating blade 65 positioned most upstream in the sheet conveying direction among the four layer thickness regulating blades 65 is positioned between the sheet guide 54 and the first auger 63. Furthermore, each of the four layer thickness regulating blades 65 is positioned between the sheet guide 54 and the first and second augers 63, 64 in the third direction.

[0075] like Figure 1 As shown, the transfer unit 70 is configured to transfer the toner image on the photosensitive drum 51 to the sheet S. The transfer unit 70 is positioned between the sheet supply unit 20 and the drum unit 50. The transfer unit 70 includes a driving roller 71, a driven roller 72, a conveying belt 73, and a transfer roller 74.

[0076] The drive roller 71 and the driven roller 72 are separated from each other in the first direction. The conveyor belt 73 is an endless belt that loops around the drive roller 71 and the driven roller 72. The conveyor roller 74 is positioned in the space surrounded by the conveyor belt 73. The conveyor belt 73 is sandwiched between the photosensitive drum 51 and the transfer roller 74. The conveyor belt 73 is an example of a transfer member.

[0077] The fixing unit 80 includes a heat roller 81 and a pressure roller 82. The sheet S is nipped between the heat roller 81 and the pressure roller 82. The discharge unit 90 includes a plurality of discharge rollers 91.

[0078] In the image forming unit 30 , the scorotron charger 52 charges the surface of the photosensitive drum 51 , and thereafter the scanner unit 40 irradiates a laser beam to the surface of the photosensitive drum 51 , thereby forming an electrostatic latent image on the surface of the photosensitive drum 51 .

[0079] The toner cartridge TC replenishes toner into the interior of the developer container 62. The first auger 63 conveys the toner and carrier in the developer container 62 to the second auger 64. The second auger 64 supplies toner to the magnetic roller 61. The magnetic roller 61 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 51. As a result, a toner image is formed on the photosensitive drum 51.

[0080] The conveyor belt 73 conveys the sheet S so that the sheet S passes through the portion between the photosensitive drum 51 and the transfer roller 74. At this point, the toner images formed on the respective photosensitive drums 51 are sequentially transferred onto the sheet S. The sheet S then passes through the portion between the heat roller 81 and the pressure roller 82. At this point, the toner images on the sheet S are thermally fixed to the sheet S. The conveyor roller 91 then conveys the sheet S to a location outside the housing 10.

[0081] like Figure 4A As shown, the developing unit 60 has one end portion in the second direction including a boss 60A and a pair of protrusions 60B. The boss 60A extends in the second direction and has an outer peripheral surface centered on the second axis X2.

[0082] The pair of protrusions 60B protrude from the outer peripheral surface of the boss 60A in a direction perpendicular to the second direction. The second axis X2 is positioned between the pair of protrusions 60B. The boss 60A extends farther away from the developer container 62 than the pair of protrusions 60B.

[0083] like Figure 4B As shown, the developing unit 60 has another end portion in the second direction including a shaft 60C. The shaft 60C extends in the second direction. The shaft 60C has an outer peripheral surface centered on the second axis X2. The outer diameter of the shaft 60C is smaller than the outer diameter of the boss 60A. The inlet 62A is located at the other end portion in the second direction of the developer container 62.

[0084] like Figure 5As shown, the developer container 62 includes a first storage chamber 62B, a second storage chamber 62C, and a partition wall 62D, and is formed with a supply opening 62E and a recovery opening 62F. The first storage chamber 62B defines an internal space for accommodating the first auger 63. The second storage chamber 62C defines an internal space for accommodating the second auger 64. Toner and carrier are accommodated in the first storage chamber 62B and the second storage chamber 62C.

[0085] The partition wall 62D partitions the developer container 62 into a first storage chamber 62B and a second storage chamber 62C. A supply opening 62E is located at one end of the partition wall 62D in the second direction. The supply opening 62E allows the first storage chamber 62B and the second storage chamber 62C to communicate with each other. The supply opening 62E allows toner and carrier to move from the first storage chamber 62B to the second storage chamber 62C.

[0086] The recovery opening 62F is located at the other end of the partition wall 62D in the second direction. The recovery opening 62F allows the first storage chamber 62B and the second storage chamber 62C to communicate with each other. The supply opening 62E allows the toner and carrier to move from the second storage chamber 62C to the first storage chamber 62B.

[0087] The inlet 62A opens to the first storage chamber 62B. The distance from the inlet 62A to the supply opening 62E is greater than the distance from the inlet 62A to the recovery opening 62F.

[0088] The first auger 63 is configured to convey the toner supplied to the first storage chamber 62B through the inlet 62A, together with the carrier, to the supply opening 62E. The second auger 64 is configured to convey the toner supplied to the second storage chamber 62C through the supply opening 62E toward the other end of the developer container 62 in the second direction. The toner conveyed in the second direction by the second auger 64 is attracted to the surface of the magnetic roller 61 due to its magnetic force. The toner and carrier conveyed to the other end of the developer container 62 in the second direction are moved to the first storage chamber 62B through the recovery opening 62F.

[0089] like Figure 6 As shown in FIG9 , the frame of the drum unit 50 that supports the photosensitive drum 51 and the developing unit 60 includes a first side wall W1, a second side wall W2, a third side wall W3, a fourth side wall W4, a front wall W5, and a rear wall W6. The frame is configured to support the photosensitive drum 51 and the developing unit 60. These walls W3, W4, W5, and W6 are made of resin.

[0090] Each developing unit 60 is positioned between the third side wall W3 and the fourth side wall W4 in the second direction. The front wall W5 spans between one end of the third side wall W3 in the first direction and one end of the fourth side wall W4 in the first direction. The rear wall W6 spans between the other end of the third side wall W3 in the first direction and the other end of the fourth side wall W4 in the first direction.

[0091] The third side wall W3 includes a cartridge supporting portion W31. The cartridge supporting portion W31 is configured to support the outer peripheral surface of the toner cartridge TC. The fourth side wall W4 includes a cartridge supporting portion similar to the cartridge supporting portion W31.

[0092] like Figure 7 and Figure 8 As shown, the first side wall W1 and the second side wall W2 are plates that support each end portion in the second direction of the photosensitive drum 51 and the developing unit 60. For example, the first side wall W1 and the second side wall W2 are made of metal.

[0093] The first side wall W1 is formed with four first holes W11. The first hole W11 allows the boss 60A positioned at one end of the developing unit 60 in the second direction to extend through the first hole W11. That is, the boss 60A is inserted into the first hole W11. Therefore, the boss 60A is supported by the first side plate W1. The second side wall W2 faces the first side wall W1 in the second direction. The second side wall W2 is formed with four second holes W21. The pair of protrusions 60B positioned on the outer peripheral surface of the boss 60A contacts the surface W12 of the first side wall W1 facing the second side wall W2 to fix the position of the developing unit 60 in the second direction (see Figure 9B and 9C The fourth side wall W4 is positioned relative to the first side wall W1 and the second side wall W2.

[0094] like Figure 7 As shown, the drum unit 50 includes four cylindrical members P. Each of the four cylindrical members P includes a cylindrical body P1 and a flange P2.

[0095] The cylinder P1 has a cylindrical shape. The cylinder P1 is inserted into the second hole W21. The cylinder P1 has an outer peripheral surface P11 and an opening P12. The shaft 60C ( Figure 4B as shown) is inserted into the opening P12.

[0096] The flange P2 protrudes radially outward from the outer peripheral surface P11 of the cylinder P1. The flange P2 is positioned opposite to the first side wall W1 relative to the second side wall W2. The third side wall W3 is positioned opposite to the first side wall W1 relative to the second side wall W2.

[0097] like Figure 9CAs shown, the flange P2 is positioned between the second side wall W2 and the third side wall W3 in the second direction. The first side wall W1 and the second side wall W2 are positioned between the third side wall W3 and the fourth side wall W4 in the second direction.

[0098] Next, a method of assembling the drum unit 50 will be described. Figure 9A As shown, each photosensitive drum 51 is attached to the first side wall W1 and the second side wall W2. Although illustration is omitted, a unit including a scorotron charger 52 and a cleaning roller 53 is also attached to the first side wall W1 and the second side wall W2.

[0099] Then, if Figure 9A and 9B As shown, the shaft 60C of the developing unit 60 is inserted into the second hole W21 of the second side wall W2. Then, the boss 60A of the developing unit 60 is inserted into the first hole W11 in the direction from the second side wall W2 to the first side wall W1. As a result, the pair of protrusions 60B contact the surface W12 of the first side wall W1, which faces the second side wall W2.

[0100] After the pair of protrusions 60B come into contact with the surface W12 of the first side wall W1 that faces the second side wall W2, the cylindrical member P is inserted into the second hole W21 in the direction from the second side wall W2 to the first side wall W1 and attached to the shaft 60C of the developing unit 60. Thus, the flange P2 is positioned opposite to the first side wall W1 with respect to the second side wall W2.

[0101] Then, if Figure 9C As shown, the third side wall W3 is attached to the surface of the second side wall W2 opposite to the surface of the second side wall W2 facing the first side wall W1. In addition, the fourth side wall W4 is attached to the surface of the first side wall W1 opposite to the surface W12.

[0102] In this embodiment, the following effects can be achieved: the toner cartridge TC can be attached to the drum unit 50, and toner is directly replenished from the toner cartridge TC attached to the drum unit 50 to the developing container 62. Therefore, the conventional toner replenishing device can be omitted, and thus the size increase of the drum unit 50 and the color printer 1 can be suppressed.

[0103] Since the flange P2 is positioned opposite to the first side wall W1 with respect to the second side wall W2 , the release of the cylindrical member P from the second side wall W2 can be restricted.

[0104] Since the flange P2 is sandwiched between the second side wall W2 and the third side wall W3, the release of the cylindrical member P from the second side wall W2 can be further restricted.

[0105] Since the first side wall W1 and the second side wall W2 are positioned between the third side wall W3 and the fourth side wall W4 , the first side wall W1 and the second side wall W2 may be protected by the third side wall W3 and the fourth side wall W4 .

[0106] Various modifications are conceivable. For example, the first direction is perpendicular to the second direction. However, the first direction may be directed parallel to the second direction.

[0107] In the above embodiment, the scorotron charger 52 is exemplified as the charger. However, a charging roller may be used as the charger.

[0108] The drum unit according to the above-described embodiment is applied to the color printer 1. However, the drum unit may be applied to image recording apparatuses other than the color printer 1, such as a monochrome printer, a copier, and a multifunction peripheral.

[0109] In the above-described embodiment, heavy paper, postcards, and thin paper are used as the sheet S. However, an OHP sheet can also be used as the sheet S.

[0110] In the above disclosure, the conveyor belt 73 is exemplified as the transfer member. However, a transfer roller that contacts the photosensitive drum 51 may be used as the transfer member.

[0111] Although the present disclosure has been described in detail with reference to specific embodiments and modifications, it will be apparent to one skilled in the art that various changes and modifications can be made without departing from the scope and spirit of the present disclosure.

[0112] [Reference Symbol List]

[0113] 1: Color printer

[0114] 10: Shell

[0115] 10A: Open

[0116] 11: Front cover

[0117] 50: Drum unit

[0118] 51: Photosensitive drum

[0119] 60: Development unit

[0120] 61: Magnetic roller

[0121] 62: Development container

[0122] 62A: Entrance

[0123] 63: First Auger

[0124] 64: Second auger

[0125] TC: Toner Cartridge

[0126] X1: First axis

[0127] X2: Second axis

[0128] X3: The third axis

[0129] X4: The fourth axis

Claims

1. An image forming apparatus, characterized in that: include: a housing formed with an opening and having a front cover movable between an open position in which the front cover opens the opening and a closed position in which the front cover closes the opening; a toner cartridge configured to accommodate toner therein; as well as a drum unit to which the toner cartridge is attachable, wherein the drum unit is movable in a first direction relative to the housing in a state where the toner cartridge is attached to the drum unit, the drum unit being movable through the opening between a storage position in which the drum unit is positioned in the housing and a pulled-out position in which the drum unit is pulled out of the housing, the drum unit comprising: a photosensitive drum rotatable about a first axis extending in a second direction; and a developing unit positioned between the toner cartridge and the photosensitive drum, the developing unit comprising: a magnetic roller positioned between the toner cartridge and the photosensitive drum and rotatable about a second axis extending in the second direction, the magnetic roller facing a surface of the photosensitive drum; a developer container configured to accommodate a carrier, the developer container being formed with an inlet for allowing replenishment of the toner from the toner cartridge; a first auger positioned in the developer container and rotatable about a third axis extending in the second direction, the first auger configured to circulate the toner and the carrier in the developer container; and a second auger positioned in the developer container and rotatable about a fourth axis extending in the second direction, the second auger being configured to convey the toner and the carrier to the magnetic roller, wherein the photosensitive drum comprises an array of a plurality of photosensitive drums arranged one above the other in the first direction; and The developing unit includes an array of a plurality of developing units arranged in the first direction.

2. The image forming apparatus according to claim 1, wherein in, The first direction intersects with the second direction.

3. The image forming apparatus according to claim 1, wherein in, The inlet is positioned opposite the magnetic roller relative to the first auger and the second auger.

4. The image forming apparatus according to claim 1, wherein A transfer member configured to transfer the toner image on the photosensitive drum to a sheet is further included.

5. The image forming apparatus according to claim 1, wherein in, The drum unit further includes a sheet guide configured to guide the sheet toward the photosensitive drum.

6. The image forming apparatus according to claim 1, wherein in, The drum unit further includes a cleaning roller configured to clean the photosensitive drum.

7. The image forming apparatus according to claim 1, wherein in, the inlet being positioned above the first auger and the second auger; and wherein the second axis is positioned below the first auger and the second auger.

8. The image forming apparatus according to claim 7, wherein: in, The developing unit further includes a layer thickness regulating member configured to regulate a thickness of a toner layer formed on the magnetic roller, the layer thickness regulating member not being in contact with the magnetic roller.

9. The image forming apparatus according to claim 8, wherein in, The layer thickness regulating member is positioned below the first auger and the second auger.

10. The image forming apparatus according to any one of claims 1 to 9, wherein: in, The magnetic roller is positioned away from the surface of the photosensitive drum.

11. The image forming apparatus according to any one of claims 1 to 9, wherein: in, The first auger is positioned closer to the inlet than the second auger is to the inlet.

12. The image forming apparatus according to any one of claims 1 to 9, wherein: in, the first auger being configured to convey the toner replenished from the inlet to the second auger; wherein the second auger is configured to supply the toner conveyed by the first auger to the magnetic roller; and The magnetic roller is configured to supply the toner supplied from the second auger to the photosensitive drum.

13. The image forming apparatus according to any one of claims 1 to 9, wherein: in, The drum unit further comprises: a first side wall having a first hole formed therein, wherein the first hole allows one end portion of the developing unit in the second direction to be inserted into the first hole so that the one end portion is supported by the first side wall; a second side wall, the second side wall being formed with a second hole, the second side wall facing the first side wall in the second direction; and A cylindrical member is inserted into the second hole, the cylindrical member having an opening into which the other end portion of the developing unit in the second direction is inserted.

14. The image forming apparatus according to claim 13, wherein in, The one end portion of the developing unit in the second direction includes: a boss extending in the second direction and inserted into the first hole; and A protrusion protrudes from the boss in a direction perpendicular to the second direction, the protrusion contacting a surface of the first side wall facing the second side wall to fix a position of the developing unit in the second direction.

15. The image forming apparatus according to claim 14, wherein in, The cylindrical member comprises: a cylindrical portion inserted into the second hole and having an outer peripheral surface; and A flange protrudes from the outer peripheral surface, the flange being positioned opposite the first side wall relative to the second side wall.

16. The image forming apparatus according to claim 15, wherein in, The drum unit further includes a third side wall positioned opposite the first side wall relative to the second side wall, and Wherein, the flange is positioned between the second side wall and the third side wall.

17. The image forming apparatus according to claim 16, wherein: in, The drum unit further includes a fourth side wall positioned opposite the second side wall relative to the first side wall; The first side wall and the second side wall are positioned between the third side wall and the fourth side wall in the second direction.

18. The image forming apparatus according to any one of claims 1 to 9, wherein: in, The drum unit further includes a charger configured to charge the photosensitive drum.

19. The image forming apparatus according to claim 18, wherein in, The charger is a scorotron charger.

20. The image forming apparatus according to claim 17, wherein in, After the boss is inserted into the first hole in a direction from the second side wall to the first side wall, the protrusion contacts the surface of the first side wall facing the second side wall; wherein, after the protrusion contacts the surface of the first side wall facing the second side wall, the cylindrical member is inserted into the second hole in the direction from the second side wall to the first side wall so that the cylindrical member is attached to the other end portion of the developing unit, and the flange is positioned opposite to the first side wall with respect to the second side wall; wherein the third side wall is attached to the second side wall, the third side wall being positioned opposite the first side wall relative to the second side wall; and The fourth side wall is attached to the first side wall, and the fourth side wall is positioned opposite to the second side wall relative to the first side wall.

21. A drum unit, characterized in that: A toner cartridge is attachable to the drum unit, the toner cartridge being configured to accommodate toner therein, the drum unit being movable in a first direction relative to the housing in a state where the toner cartridge is attached to the drum unit, the drum unit being movable through the opening between an accommodated position where the drum unit is positioned in the housing and a pulled-out position where the drum unit is pulled out of the housing, the drum unit comprising: a photosensitive drum rotatable about a first axis extending in a second direction; and a developing unit positioned between the toner cartridge and the photosensitive drum, the developing unit comprising: a magnetic roller positioned between the toner cartridge and the photosensitive drum and rotatable about a second axis extending in the second direction, the magnetic roller facing a surface of the photosensitive drum; a developer container configured to accommodate a carrier, the developer container being formed with an inlet for allowing replenishment of the toner from the toner cartridge; a first auger positioned in the developer container and rotatable about a third axis extending in the second direction, the first auger configured to circulate the toner and the carrier in the developer container; and a second auger positioned in the developer container and rotatable about a fourth axis extending in the second direction, the second auger being configured to convey the toner and the carrier to the magnetic roller, wherein the photosensitive drum comprises an array of a plurality of photosensitive drums arranged one above the other in the first direction; and The developing unit includes an array of a plurality of developing units arranged in the first direction.

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