JP2023134988A - drum unit - Google Patents

Abstract

To provide a drum unit that can prevent carrier on a magnetic roller from falling to the outside.SOLUTION: A drum unit 50 comprises: a photoconductor drum 51; a developer container 62 that can store toner and carrier, a magnetic roller 61 that carries the toner and carrier in the developer container 62; a blade 65 that regulates the layer thickness of the toner and carrier on the magnetic roller 61; and a roller cover 120 that covers the magnetic roller 61. The roller cover 120 is bent along the outer periphery of the magnetic roller 61, and is configured to cover the toner and carrier on the magnetic roller 61 regulated by the blade 65.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to a drum unit.

Conventionally, a configuration is known that includes a main body casing, a drum unit that is removable from the main casing, and a toner cartridge that is removable from the drum unit. According to the structure of Patent Document 1, the drum unit includes a photosensitive drum, a magnetic roller, and a developer container that contains a two-component developer containing toner and carrier. The drum unit is movable between a storage position located within the main body casing and a drawn-out position where the drum unit is pulled out from the main body casing. As a result, the user can replace the toner cartridge with the drum unit pulled out, resulting in good operability.

JP2021-162780A

The magnetic roller carries the toner and carrier in the developer container and supplies the toner to the photosensitive drum. During the process until toner is supplied to the photosensitive drum, a small amount of carrier may fall from the magnetic roller to the outside of the drum unit.

Therefore, an object of the present disclosure is to provide a configuration that can suppress a small amount of carrier from falling from the magnetic roller to the outside of the drum unit.

In order to solve the above-mentioned problems, a drum unit according to a first aspect of the present disclosure is a drum unit in which a toner cartridge containing toner is detachable, and includes a photosensitive drum and a developing container capable of containing toner and carrier. , a developer container to which toner is replenished from the toner cartridge, a magnetic roller that can support the toner and carrier in the developer container, the magnetic roller facing the photosensitive drum, and regulating the layer thickness of the toner and carrier on the magnetic roller. a roller cover facing the magnetic roller, the roller cover being curved along the outer periphery of the magnetic roller and configured to cover the toner and carrier on the magnetic roller regulated by the blade; , is provided.

According to the drum unit of the first aspect, the carrier that has fallen from the magnetic roller can be held by the roller cover.

Further, in the drum unit of the second aspect, in the drum unit of the first aspect, the roller cover has one end and the other end located away from the one end in the axial direction of the photosensitive drum, and the magnetic roller carries the toner and carrier. The carrying region is located axially between one end and the other end.

According to the drum unit of the second aspect, the roller cover can cover the entire area where the magnetic roller carries toner and carrier.

The drum unit of the third aspect is the drum unit of the first aspect or the second aspect, and is located in the developer container, and includes a first auger that moves toner and carrier in the developer container in the axial direction of the photosensitive drum. A first auger that conveys the toner, and a second auger that is located inside the developer container, is aligned with the first auger in the orthogonal direction perpendicular to the axial direction, and faces the magnetic roller, and the second auger is arranged to convey the toner in the developer container. and a second auger that transports the carrier in a direction opposite to the direction in which the first auger transports the carrier. The second auger is located between the magnetic roller and the toner cartridge in the second direction when the toner cartridge is attached to the drum unit, and at least a portion of the roller cover is arranged so that the magnetic roller and the second auger face each other. located opposite the second auger in direction with respect to the magnetic roller.

According to the drum unit of the third aspect, during the process in which the toner and carrier carried by the magnetic roller are carried from the developer container to a position opposite to the second auger, the roller cover can hold the carrier that has fallen from the magnetic roller.

In the drum unit according to a fourth aspect, in the drum unit according to any one of the first to third aspects, the magnetic roller has a first magnetic pole facing the blade, and a first magnetic pole for carrying toner and carrier whose layer thickness is regulated by the blade. It has two magnetic poles and a third magnetic pole facing the photosensitive drum, and at least a portion of the roller cover faces the second magnetic pole.

According to the drum unit of the fourth aspect, the magnetic roller can recover the carrier that has fallen onto the roller cover again using the second magnetic pole.

In the drum unit of the fifth aspect, in the drum unit of any one of the first to fourth aspects, the distance between the surface of the roller cover facing the surface of the magnetic roller and the surface of the magnetic roller is 0.5 mm to 3 mm. It is within the range of .0mm.

According to the drum unit of the fifth aspect, it is possible to suppress the carrier from falling to the outside of the drum unit within a range where the rotational torque of the magnetic roller does not become too large.

In the drum unit of the sixth aspect, in the drum unit of any one of the first to fifth aspects, the roller cover is fixed to the blade with a screw. According to the drum unit of the sixth aspect, the roller cover can be easily attached. It is.

In a drum unit according to a seventh aspect, in the drum unit according to any one of the first to sixth aspects, the roller cover is a flat plate extending in the axial direction of the photosensitive drum, and includes a flat plate attached to the blade and a curved plate extending from the first plate. The roller cover has a first rib that connects the flat plate and the curved plate.

According to the drum unit of the seventh aspect, the first rib can suppress the bending of the curved plate.

According to the drum unit of the eighth aspect, in the drum unit of the seventh aspect, the roller cover has a plurality of first ribs, and the plurality of first ribs are arranged at equal intervals in the axial direction. The plurality of first ribs makes the strength of the roller cover uniform in the first direction.

In a drum unit according to a ninth aspect, in the drum unit according to any one of the first to eighth aspects, the toner cartridge has a discharge port that allows the toner to be discharged, and the developer container has a discharge port that allows the toner to be discharged from the discharge port. It has a replenishment port that allows toner to be replenished.

According to the drum unit of the ninth aspect, toner can be directly supplied to the drum unit from the toner cartridge.

An image forming apparatus according to a tenth aspect is an image forming apparatus in which the drum unit according to any one of the first to ninth aspects can be detachably attached, and the image forming apparatus contacts the photosensitive drum and transfers the toner image on the photosensitive drum to paper. The image forming apparatus is equipped with a transfer belt for use in the image forming apparatus, and the roller cover is located between the magnetic roller and the transfer belt.

According to the drum unit of the tenth aspect, it is possible to suppress the carrier from falling from the magnetic roller onto the transfer belt.

According to one aspect of the present disclosure, it is possible to suppress a small amount of carrier from falling from the magnetic roller to the outside of the drum unit.

FIG. 1 is a sectional view showing a color printer of this embodiment. FIG. 3 is a cross-sectional view showing the drum unit in a pulled-out position. FIG. 3 is a cross-sectional view showing a drum unit with a toner cartridge installed therein. It is a perspective view of a drum unit. FIG. 3 is a cross-sectional view of the developing unit viewed from one end side in a third direction. FIG. 3 is a cross-sectional view of the developing unit viewed from one end side in a first direction. FIG. 3 is a perspective view of the developing unit. They are drawings of the developing unit, (a) a view of the developing unit viewed from one end side in the second direction, and (b) a view of the developing unit viewed from the other end side of the third direction.

Next, one embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. Note that in the following description, the axial direction of the photosensitive drum 51 will be referred to as the first direction. The drum axis X1 of the photosensitive drum 51 extends in the first direction, and has a second direction that is orthogonal to the first direction. The first auger 63 and the second auger 64 are lined up in the second direction. Further, the direction in which the magnetic roller 61 and the second auger 64 face each other is defined as a third direction. The third direction intersects the second direction and the first direction. Preferably, the third direction is perpendicular to the second direction and the first direction. Furthermore, in the following description, one end side of the main body casing 10 in the third direction will be referred to as "upper", and the other end side of the main body casing 10 in the third direction will be referred to as "lower". For example, in FIG. 2, the toner cartridge TC is located above the first auger 63, and the magnetic roller 61 is located below the second auger 64.

(1) Description of the color printer 1 As shown in FIG. 1, the color printer 1 as an example of an image forming apparatus includes a main body housing 10, a front cover 11, a main body connector 12, a sheet supply section 20, and an image forming apparatus. It includes a forming section 30, a discharge section 90, and a control section 100.

The main body case 10 has an opening 10A. The opening 10A is located at one end of the main body casing 10 in the first direction.

The front cover 11 is movable between an open position where the opening 10A is opened and a closed position where the opening 10A is closed. Specifically, the front cover 11 is rotatable between an open position and a closed position.

The main body connector 12 is electrically connected to the control section 100. The main body connector 12 is located within the main body housing 10.

The sheet supply section 20 includes a supply tray 21 and a sheet conveyance mechanism 22. The supply tray 21 accommodates the sheets S. The sheet transport mechanism 22 transports the sheet S from the supply tray 21 to the image forming section 30.

The image forming section 30 includes a scanner unit 40, a drum unit 50, four toner cartridges TC, a transfer device 70, and a fixing device 80.

The scanner unit 40 includes a laser emitting section, a polygon mirror, a lens, a reflecting mirror, etc. (not shown). The scanner unit 40 emits a laser beam to the photosensitive drum 51.

The drum unit 50 is movable in the first direction with respect to the main body housing 10 via the opening 10A.

As shown in FIGS. 1 and 2, the drum unit 50 is located at a first position with respect to the main body casing 10 between an accommodation position located within the main body casing 10 and a pulled-out position where it is pulled out from the main body casing 10. It is possible to move in the direction. The drum unit 50 is supported by the main body casing 10 so as to be movable between a housed position and a pulled-out position. The drum unit 50 is removable from the main body housing 10.

As shown in FIG. 2, the drum unit 50 includes a plurality of photosensitive drums 51, a plurality of Scorotron chargers 52, a plurality of cleaning rollers 53, a plurality of developing units 60, a sheet guide 54, and a connector 55. Be prepared. Specifically, the drum unit 50 includes four photosensitive drums 51, four scorotron chargers 52, four cleaning rollers 53, four developing units 60, a sheet guide 54, and a connector 55.

The plurality of photosensitive drums 51, the plurality of Scorotron chargers 52, the plurality of cleaning rollers 53, and the plurality of developing units 60 form images of mutually different colors (for example, cyan, magenta, yellow, and black). The plurality of photosensitive drums 51 are arranged in the second direction. However, in this embodiment, the plurality of photosensitive drums 51, the plurality of Scorotron chargers 52, the plurality of cleaning rollers 53, and the plurality of developing units 60 have the same configuration except for the color of toner used to form an image. Therefore, only one of the plurality of cases will be described below.

The photosensitive drum 51 is rotatable about a drum axis X1 extending in the first direction.

The scorotron charger 52 is a charger that charges the photosensitive drum 51.

The cleaning roller 53 is a roller that cleans the photosensitive drum 51.

The developing unit 60 is located between the toner cartridge TC and the photosensitive drum 51 in the third direction. The developing unit 60 includes a magnetic roller 61, a developing container 62, a first auger 63, a second auger 64, a blade 65, a blade holder 67, and a roller cover 120.

The magnetic roller 61 is a roller that supplies toner to the photosensitive drum 51. The magnetic roller 61 is rotatable about a magnetic roller axis X2 extending in the first direction.

The sheet guide 54 is a guide that guides the sheet S toward the photosensitive drum 51. The sheet guide 54 is aligned with the photosensitive drum 51 in the second direction. The sheet guide 54 is located upstream of the four photosensitive drums 51 in the conveyance direction of the sheet S.

The magnetic roller 61 located most upstream in the conveyance direction of the sheet S is located between the sheet guide 54 and the second auger 64 in the third direction. The blade 65 located most upstream in the conveyance direction of the sheet S is located between the sheet guide 54 and the first auger 63 in the third direction.

Connector 55 is located on the outer surface of drum unit 50.

The toner cartridge TC contains toner which is a non-magnetic material. As shown in FIG. 1, the toner cartridge TC has an outlet TO that allows the stored toner to be discharged. Further, as shown in FIG. 3, the toner cartridge TC is removable from the drum unit 50 in the third direction.

The toner cartridge TC has a toner memory TM. The toner memory TM stores toner cartridge information regarding the toner cartridge TC. The toner cartridge information is at least one of identification information that can identify each toner cartridge TC and toner life information of the toner cartridge TC. The identification information is, for example, a serial number. The toner life information is, for example, at least one of the cumulative number of rotations of the magnetic roller 61 or the first auger 63, the count of used dots, and the remaining amount of toner.

As shown in FIG. 1, the transfer device 70 is a member that transfers the toner image on the photosensitive drum 51 onto the sheet S. As shown in FIG. The transfer device 70 is located between the sheet supply section 20 and the drum unit 50. The transfer device 70 includes a drive roller 71, a driven roller 72, a transfer belt 73, and four transfer rollers 74.

The driving roller 71 and the driven roller 72 are located apart from each other in the first direction. A driving roller 71 and a driven roller 72 support a transfer belt 73. The transfer belt 73 is an endless belt. The transfer roller 74 is located inside the transfer belt 73. The transfer roller 74 sandwiches the transfer belt 73 with the photosensitive drum 51.

The fixing device 80 includes a heating roller 81 and a pressure roller 82. The pressure roller 82 and the heating roller 81 sandwich the sheet S therebetween.

A series of operations when the image forming section 30 forms an image are as follows.

In the image forming section 30, the scorotron charger 52 charges the surface of the photosensitive drum 51. Thereafter, the scanner unit 40 forms an electrostatic latent image on the photosensitive drum 51 by exposing the surface of the photosensitive drum 51 to light.

The magnetic roller 61 forms a toner image on the photosensitive drum 51 by supplying toner to the electrostatic latent image formed on the photosensitive drum 51 . Thereafter, the transfer belt 73 conveys the sheet S conveyed from the sheet supply section 20 toward the photosensitive drum 51. The transfer roller 74 transfers the toner image on the photosensitive drum 51 onto the sheet S by pressing the sheet S sandwiched between the transfer belt 73 and the photosensitive drum 51 from inside the transfer belt 73 toward the photosensitive drum 51. . The fixing device 80 fixes the toner image onto the sheet S by sandwiching the sheet S onto which the toner image has been transferred between a heating roller 81 and a pressure roller 82 .

The discharge section 90 includes a plurality of conveyance rollers 91. The conveying roller 91 discharges the sheet S that has passed through the fixing device 80 to the outside of the main body housing 10 .

The control unit 100 includes, for example, a CPU, a RAM, a ROM, and an input/output circuit. The control unit 100 controls the color printer 1 by, for example, performing arithmetic processing based on a program or data stored in a ROM.

As shown in FIG. 1, the connector 55 is electrically connected to the color printer 1 when the drum unit 50 is attached to the main body housing 10. When the connector 55 is electrically connected to the main body connector 12 with the toner cartridge TC installed in the drum unit 50, the control unit 100 acquires toner cartridge information from the toner memory TM or stores the information in the toner memory TM. It becomes possible to write.

(2) Description of the developing unit 60 (2-1) Description of the developing container 62 The developing container 62 is a container that contains toner, which is a non-magnetic material, and carrier, which is a magnetic material. The carrier is, for example, iron powder. The developer container 62 has a supply port 62A, a first storage chamber 62B, a second storage chamber 62C, a supply port 62E, and a recovery port 62F.

As shown in FIG. 3, the supply port 62A is located on the opposite side of the magnetic roller 61 in the third direction with respect to the first auger 63 and the second auger 64. The supply port 62A is located above the first auger 63 in the third direction. Further, as shown in FIG. 4, the replenishment port 62A is located on one end side of the developer container 62 in the first direction. The supply port 62A communicates the first storage chamber 62B with the outside of the developer container 62. The replenishment port 62A allows toner to be replenished from the discharge port TO of the toner cartridge TC. When the toner cartridge TC is attached to the drum unit 50, the toner cartridge TC becomes capable of replenishing the developer container 62 with toner from the discharge port TO through the replenishment port 62A.

As shown in FIG. 5, the first accommodation chamber 62B accommodates the first auger 63. The second storage chamber 62C stores the second auger 64. The first storage chamber 62B and the second storage chamber 62C contain toner and carrier.

The supply port 62E is located on the other end side of the developer container 62 in the first direction. The supply port 62E allows toner and carrier to move from the first storage chamber 62B to the second storage chamber 62C.

The collection port 62F is located on one end side of the developer container 62 in the first direction. The collection port 62F allows the toner and carrier to move from the second storage chamber 62C to the first storage chamber 62B.

(2-2) Configuration of the first auger 63 and the second auger 64 As shown in FIG. 5, the first auger 63 and the second auger 64 are located within the developer container 62. The first auger 63 is located closer to the supply port 62A than the second auger 64.

The first auger 63 is rotatable about a first auger shaft X3 extending in the first direction. The first auger 63 has a first auger shaft 63A and a first auger blade 63B. The first auger shaft 63A is rotatable about the first auger shaft X3 extending in the second direction. The first auger blade 63B is located on the outer periphery of the first auger shaft 63A. The first auger blade 63B has a spiral shape.

The first auger 63 transports the toner and carrier from one end side of the developer container 62 toward the other end side in the first direction. Specifically, the first auger 63 transports the toner supplied from the supply port 62A to the first storage chamber 62B, together with the carrier, to the supply port 62E. Further, the first auger 63 transports the toner and carrier supplied from the collection port 62F to the first storage chamber 62B to the supply port 62E. The toner and carrier transported to the supply port 62E are transported from the first storage chamber 62B to the second storage chamber 62C via the supply port 62E.

The second auger 64 has a second auger shaft 64A and a second auger blade 64B. The second auger shaft 64A is rotatable about a second auger shaft extending in the second direction. The second auger blade 64B is located on the outer periphery of the second auger shaft 64A. The second auger blade 64B has a spiral shape.

The second auger 64 transports the toner and carrier from the other end of the developer container 62 toward the one end in the second direction. The second auger 64 transports the toner and carrier supplied from the supply port 62E to the second storage chamber 62C to the collection port 62F. The toner and carrier transported in the second direction by the second auger 64 adhere to the sleeve 61B of the magnetic roller 61 due to the magnetic force of the magnetic roller 61. The toner and carrier transported to the collection port 62F are transported from the second storage chamber 62C to the first storage chamber 62B via the collection port 62F.

The first auger 63 and the second auger transport and simultaneously stir the toner and carrier in the developer container 62. As the first auger 63 and the second auger 64 stir the toner and carrier, the toner is triboelectrically charged.

In this way, the first auger 63 and the second auger 64 can transport toner and carrier toward the magnetic roller 61 from the supply port 62A. Further, the first auger 63 and the second auger 64 circulate the toner and carrier within the developer container 62.

(2-3) Description of Blade 65 and Blade Holder 67 As shown in FIG. 6, the blade 65 is located below the first auger 63. The blade 65 is a member that regulates the thickness of the toner layer on the magnetic roller 61. The blade 65 is made of metal material. The blade 65 is not in contact with the magnetic roller 61.

The blade 65 is fixed to the blade holder 67 with a screw. Thereby, the blade 65 is attached to the developer container 62 via the blade holder 67. The blade holder 67 is located between the blade 65 and the developer container 62 in the third direction. The blade holder 67 is an L-shaped metal.

(2-4) Description of magnetic roller 61 The magnetic roller 61 is located below the first auger 63 and the second auger 64 in the third direction. The magnetic roller 61 is located between the toner cartridge TC and the photosensitive drum 51 in the third 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. The magnetic roller 61 has a magnetic roller shaft 61A and a sleeve 61B.

The magnetic roller shaft 61A is fixed to the developer container 62. In other words, the magnetic roller shaft 61A does not rotate relative to the developer container 62.

The magnetic roller shaft 61A has different magnetic poles in the circumferential direction. Specifically, as shown in FIG. 6, the magnetic poles are arranged in the order of regulation pole S1, first transport pole N1, second transport pole S2, developing pole N2, and third transport pole S3 in the rotation direction of the sleeve 61B. There is. Here, the polarities of the magnetic poles of the regulation pole S1, the second transport pole S2, and the third transport pole S3 are S poles, and the polarities of the magnetic poles of the first transport pole N1 and developing pole N2 are N poles. .

The regulating pole S1 faces the blade 65. The first transport pole N1 and the second transport pole S2 are magnetic poles for supporting toner and carrier whose layer thickness is regulated by the blade 65. The developing pole N2 faces the photosensitive drum. The third transport pole S3 is a magnetic pole for carrying toner and carrier remaining after toner is supplied from the magnetic roller 61 to the photosensitive drum 51 to the developer container 62. Note that the regulating pole S1 is an example of a first magnetic pole. The first transport pole N1 and the second transport pole S2 are examples of second magnetic poles. The development pole N2 is an example of a third magnetic pole.

The sleeve 61B is made of, for example, a cylindrical member made of aluminum alloy. The sleeve 61B is rotatable around the magnetic roller shaft 61A. The sleeve 61B is rotatable about the magnetic roller axis X2 extending in the second direction. That is, the magnetic roller 61 is rotatable about the magnetic roller axis X2 extending in the second direction. The sleeve 61B holds toner and carrier by the magnetic force of the magnetic roller shaft 61A. Further, a developing voltage is applied to the sleeve 61B from the main body housing 10.

(2-5) Description of roller cover 120 The roller cover 120 is located between the magnetic roller 61 and the transfer belt 73 in the third direction (see FIG. 1). The roller cover 120 covers a part of the outer periphery of the magnetic roller 61. The roller cover 120 is curved along the outer periphery of the magnetic roller 61.

As shown in FIGS. 6, 7, and 8, the roller cover 120 includes a flat plate 121, a curved plate 122, a first rib 123, and a second rib 124. In this embodiment, the flat plate 121, the curved plate 122, the first rib 123, and the second rib 124 are integrally molded.

The flat plate 121 extends in the first direction. Flat plate 121 is parallel to blade 65. The flat plate 121 is fixed to the blade 65 by screws 125. Thereby, the flat plate 121 is attached to the developer container 62 via the blade 65 and blade holder 67.

The curved plate 122 extends from the flat plate 121 along the outer periphery of the magnetic roller 61. The curved plate 122 covers the lower side of the magnetic roller 61 in the third direction. In other words, the curved plate 122 is located opposite the second auger 64 with respect to the magnetic roller 61 in the third direction.

The curved plate 122 is curved along the outer periphery of the magnetic roller 61. The curved plate 122 is arranged such that the distance between the surface 122A of the curved plate 122 facing the sleeve 61B of the magnetic roller 61 and the surface of the sleeve 61B of the magnetic roller 61 is within the range of 0.5 mm to 3.0 mm. It's curved. Note that the surface 122A of the curved plate 122 facing the magnetic roller 61 is a smooth surface.

The curved plate 122 is located on the opposite side of the developer container 62 with respect to the blade 65 in the third direction. That is, the curved plate 122 is configured to cover the toner and carrier on the magnetic roller 61 regulated by the blade 65.

The curved plate 122 faces the first transport pole N1. Further, the curved plate 122 faces the second transport pole S2. Therefore, the curved plate 122 covers the toner and carrier on the magnetic roller 61 regulated by the blade 65 .

The first rib 123 connects the flat plate 121 and the curved plate 122. The first rib 123 is a rib for preventing the curved plate 122 from bending. As shown in FIG. 7, the roller cover 120 has a plurality of first ribs 123. In this embodiment, the plurality of first ribs 123 are located at equal intervals in the first direction.

The second rib 124 is located on the curved plate 122. Specifically, as shown in FIG. 6, the curved plate 122 has one end 122B connected to the flat plate 121, and the other end 122C located away from the one end 122B. The second rib 124 is located at the other end 122C of the curved plate 122. The roller cover 120 has a plurality of second ribs 124. In this embodiment, the plurality of second ribs 124 are located at equal intervals in the first direction, similarly to the plurality of first ribs 123.

As shown in FIG. 8, the roller cover 120 has one end 120A and the other end 120B located away from the one end 120A in the first direction. A region P where the magnetic roller 61 carries toner and carrier is located between one end 120A and the other end 120B of the roller cover 120 in the first direction.

(3) Effects According to the embodiment of the present disclosure described above, since the roller cover 120 is configured to cover the toner and carrier on the magnetic roller regulated by the blade 65, the roller cover 120 is Even if the carrier on the magnetic roller falls after being regulated by the blade 65, the fallen carrier can be held. Thereby, the roller cover 120 can suppress the carrier from falling to the outside of the drum unit 50. Moreover, since the roller cover 120 is curved along the outer periphery of the magnetic roller 61, the magnetic roller 61 can collect the carrier held by the roller cover 120 using magnetic force. Thereby, it is possible to suppress the amount of carrier in the developer container 62 from decreasing.

Further, since the region P where the magnetic roller 61 carries toner and carrier is located between the one end 120A and the other end 120B of the roller cover 120, the drum unit The carrier can be prevented from falling outside.

Further, since the curved plate 122 of the roller cover 120 is located opposite to the second auger 64 with respect to the magnetic roller 61 in the third direction, the toner and carrier supplied from the second auger 64 to the magnetic roller 61 are Even if the carrier is transported to the opposite side of the magnetic roller 61, it is possible to prevent the carrier from falling from the magnetic roller 61 to the outside of the drum unit.

Further, since the curved plate 122 of the roller cover 120 faces the first transport pole N1, the magnetic roller 61 can hold the carrier that has fallen onto the curved plate 122 again by the magnetic force of the first transport pole N1. Further, since the curved plate 122 of the roller cover 120 faces the second transport pole S2, the magnetic roller 61 can hold the carrier that has fallen onto the curved plate 122 again by the magnetic force of the second transport pole S2. Thereby, the magnetic roller 61 can collect the carrier that has fallen from the magnetic roller 61 onto the roller cover 120, so that it is possible to further suppress the amount of carrier in the developer container 62 from decreasing.

Furthermore, if the distance between the surface 122A of the curved plate 122 of the roller cover 120 and the surface of the sleeve 61B of the magnetic roller 61 is too small, friction between the carrier and the roller cover 120 may cause the sleeve of the magnetic roller 61 to The torque for rotating 61B increases. Furthermore, if the distance between the surface 122A of the curved plate 122 of the roller cover 120 and the surface of the sleeve 61B of the magnetic roller 61 is too large, the magnetic roller 61 will not be able to collect the carrier held by the roller cover 120. . Therefore, in an embodiment of the present disclosure, by setting the distance between the surface 122A and the surface of the sleeve 61B within the range of 0.5 mm to 3.0 mm, the torque does not become too large and the roller The carrier held by the cover 120 can be collected by the magnetic roller 61.

Further, since the roller cover 120 can be attached to the blade 65 with screws, attachment is easy. Further, when fixing the roller cover 120 with screws, the distance between the roller cover 120 and the magnetic roller 61 can be adjusted.

Moreover, since the roller cover 120 has the first rib 123 that connects the flat plate 121 and the curved plate 122, bending of the curved plate 122 with respect to the flat plate 121 can be suppressed. Thereby, the distance between the curved plate 122 and the magnetic roller 61 can be kept constant. Moreover, since the plurality of first ribs 123 are located at equal intervals in the first direction, the strength of the roller cover 120 in the first direction can be made uniform.

Furthermore, when the toner cartridge TC is attached to the drum unit 50, toner can be directly replenished from the outlet TO of the toner cartridge TC to the replenishment port 62A of the developer container 62, so there is no need to separately provide a toner replenishment device, and the drum unit 50 Enlargement can be suppressed.

Further, since the roller cover 120 is located between the magnetic roller 61 and the transfer belt 73, it is possible to suppress the carrier from falling from the magnetic roller 61 to the transfer belt 73.

(4) Modifications Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above-described embodiment, and can be implemented with appropriate modifications.

In the embodiment described above, the magnetic roller 61 had five magnetic poles, but it may have more or fewer magnetic poles.

In the embodiment described above, the distance between the surface of the curved plate facing the magnetic roller and the surface of the magnetic roller is within the range of 0.5 mm to 3.0 mm, but it is not necessarily limited to this range. It's not a thing. The distance between the surface of the curved plate facing the magnetic roller and the surface of the magnetic roller can be changed as appropriate depending on the magnitude of the magnetic force of the magnetic roller, the characteristics of the toner or carrier used, and the like.

In the embodiment described above, the roller cover is fixed with screws, but the attachment method is not limited to this. For example, it may be attached using an adhesive or double-sided tape, or it may be attached by welding.

In the embodiment described above, the blade is made of metal, but it may also be made of resin.

In the embodiment described above, a scorotron charger is used as the charger, but a charging roller may also be used.

In the embodiment described above, a cleaning roller is used as a member for cleaning the photosensitive drum, but a cleaning blade may also be used.

In the embodiment described above, the drum unit had four developing units, but the number of developing units may be greater or less than that. For example, there may be one developing unit. In that case, only one photosensitive drum is required.

The elements described in the above-mentioned embodiment and modifications can be implemented in appropriate combinations.

10 Main body housing 50 Drum unit 51 Photosensitive drum 60 Developing unit 61 Magnetic roller 61A Magnetic roller shaft 61B Sleeve 62 Developing container 62A Supply port 63 First auger 64 Second auger 65 Blade 120 Roller cover TC Toner cartridge

Claims (10)

A drum unit having a removable toner cartridge containing toner,
photosensitive drum,
a developer container capable of accommodating toner and carrier, the developer container being supplied with toner from the toner cartridge;
a magnetic roller capable of supporting toner and carrier in the developer container, and facing the photosensitive drum;
a blade that regulates the layer thickness of toner and carrier on the magnetic roller;
a roller cover facing the magnetic roller, a roller cover curved along the outer periphery of the magnetic roller, and configured to cover toner and carrier on the magnetic roller regulated by the blade; A drum unit characterized by comprising: The roller cover has one end and the other end located away from the one end in the axial direction of the photosensitive drum,
2. The drum unit according to claim 1, wherein a region where the magnetic roller carries toner and carrier is located between the one end and the other end in the axial direction. a first auger located in the developer container, the first auger transporting toner and carrier in the developer container in the axial direction of the photosensitive drum;
A second auger located within the developer container, aligned with the first auger in a direction perpendicular to the axial direction, and facing the magnetic roller; , a second auger conveying in a direction opposite to the direction in which the first auger conveys;
Furthermore,
The second auger is located between the magnetic roller and the toner cartridge in the orthogonal direction when the toner cartridge is attached to the drum unit,
At least a portion of the roller cover is located opposite to the second auger with respect to the magnetic roller in a direction in which the magnetic roller and the second auger face each other. 2. The drum unit according to 2. The magnetic roller is
a first magnetic pole facing the blade;
a second magnetic pole for supporting toner and carrier whose layer thickness is regulated by the blade;
a third magnetic pole facing the photosensitive drum;
has
The drum unit according to any one of claims 1 to 3, wherein at least a portion of the roller cover faces the second magnetic pole. The distance between the surface of the roller cover facing the surface of the magnetic roller and the surface of the magnetic roller is within a range of 0.5 mm to 3.0 mm. 4. The drum unit according to any one of 4. The drum unit according to any one of claims 1 to 5, wherein the roller cover is fixed to the blade with screws. The roller cover is
a flat plate extending in the axial direction of the photosensitive drum and attached to the blade;
a curved plate extending from the flat plate and curved along the outer periphery of the magnetic roller;
has
The drum unit according to any one of claims 1 to 6, wherein the roller cover has a first rib that connects the flat plate and the curved plate. The roller cover has a plurality of the first ribs,
The drum unit according to claim 7, wherein the plurality of first ribs are arranged at equal intervals in the axial direction. The toner cartridge has an ejection port that allows toner to be ejected,
9. The drum unit according to claim 1, wherein the developer container has a replenishment port that allows the toner discharged from the discharge port to be replenished. 10. An image forming apparatus with a detachable drum unit according to claim 1, further comprising a transfer belt for contacting the photosensitive drum and transferring the toner image on the photosensitive drum onto a sheet of paper. An image forming apparatus comprising:
The image forming apparatus is characterized in that the roller cover is located between the magnetic roller and the transfer belt.

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