Developing cartridge, process cartridge, and image forming apparatus

Abstract

To improve toner circulation and ensure a more even rate of toner degradation. [Solution] The developing cartridge 7 comprises a supply roller 72, an agitator 74 having a film 74B, and a frame 75. The film 74B rotates around a rotation axis (74X). The frame 75 has an inner wall W1 and a partition wall W2. The inner wall W1 has a first part P1, a second part P2, and a third part P3. When the developing cartridge 7 is mounted in the housing 2 and ready for use, the first part P1 is located directly above the rotation axis, the second part P2 is located horizontally opposite the supply roller 72 to the rotation axis, the third part P3 is located directly below the rotation axis, and the upper end W21 of the partition wall W2 is located below the upper end 72A of the supply roller 72. During the operation of the developing cartridge 7, the film 74B rotates so as to contact the first part P1, the second part P2, and the third part P3 in that order, but does not contact the supply roller 72.

Description

Technical Field

[0001] The present disclosure relates to a developing cartridge, a process cartridge, and an image forming apparatus.

Background Art

[0002] Conventionally, as a developing cartridge, there is known one having a developing roller, a supply roller for supplying toner to the developing roller, an agitator for agitating the toner, a developing chamber in which the supply roller is disposed, a toner storage chamber in which the agitator is disposed, and a partition wall for partitioning the developing chamber and the toner storage chamber (see Patent Document 1). The upper end of the partition wall is located above the uppermost part of the supply roller. Thus, toner accumulates on the supply roller.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art, since toner easily accumulates on the supply roller, it is difficult for the toner to circulate between the developing chamber and the toner storage chamber, and there is a risk that the toner in the developing chamber deteriorates.

[0005] Therefore, an object of the present disclosure is to make the degree of deterioration of toner uniform by improving the circulation of toner in the developing cartridge.

Means for Solving the Problems

[0006] The developing cartridge of the present disclosure includes a developing roller, a supply roller, a toner storage chamber, an agitator, and a frame. The supply roller contacts the developing roller. The supply roller supplies toner to the developing roller. The agitator stirs the toner in the toner chamber. The agitator has an elastically deformable film. The film rotates around a rotation axis. The frame houses the supply roller and agitator. The frame has an inner wall for the toner storage chamber. The frame has partition walls. The partition wall extends upward from a position below the feed roller. The upper end of the partition wall is located between the feed roller and the agitator. The inner wall has a first section, a second section, and a third section. When the developing cartridge is mounted in the housing of the image forming apparatus and ready for use, the first part is located directly above the rotation axis. When the developing cartridge is ready for use, the second part is located horizontally opposite the supply roller to the rotation axis. When the developing cartridge is ready for use, the third part is located directly below the rotation axis. When the developing cartridge is ready for use, the upper end of the compartment wall is positioned below the upper end of the feed roller. During the development cartridge's operation, the film rotates so that it contacts the first, second, and third sections in that order. During the development cartridge's operation, the film does not come into contact with the feed roller.

[0007] When the developing cartridge is ready for use, configuring the upper end of the compartment wall to be lower than the upper end of the supply roller makes it easier for toner on the supply roller to return to the toner storage chamber, thereby improving the circulation of toner within the developing cartridge. Configuring the film to contact the first, second, and third parts of the inner wall allows a larger amount of toner in the toner storage chamber to be supplied to the supply roller, further improving toner circulation. Improved toner circulation allows for more even toner degradation.

[0008] Furthermore, the rotational speed of the agitator may be 25-40% of the rotational speed of the supply roller.

[0009] By setting the agitator's rotation speed to a speed significantly lower than the supply roller's rotation speed, toner degradation due to agitation by the agitator can be suppressed.

[0010] Furthermore, the upper end of the partition wall may be located outside the rotational trajectory of the leading edge of the film in its undeformed state.

[0011] Furthermore, when the developing cartridge is ready for use, the upper end of the partition wall may be located below the rotation axis of the supply roller.

[0012] When the developing cartridge is ready for use, configuring the upper end of the partition wall to be positioned below the rotation axis of the supply roller makes it easier for the toner on the supply roller to return to the toner storage chamber, thereby further improving toner circulation.

[0013] Furthermore, when the developing cartridge is ready for use, the rotation axis of the developing roller may be located above the rotation axis of the supply roller.

[0014] When the developing cartridge is ready for use, the rotation axis of the developing roller is positioned above the rotation axis of the supply roller, thereby preventing toner from accumulating between the developing roller and the supply roller.

[0015] Furthermore, when the developing cartridge is ready for use, the first part may be positioned above the upper end of the developing roller.

[0016] When the developing cartridge is ready for use, the first part is positioned above the upper end of the developing roller, which allows the toner storage chamber to be expanded upwards, thereby increasing the toner capacity.

[0017] Furthermore, when the developing cartridge is ready for use, the rotation axis of the agitator may be positioned above the rotation axis of the supply roller.

[0018] When the developing cartridge is in a usable state, by configuring the rotation axis center of the agitator to be positioned above the rotation axis center of the supply roller, the toner storage chamber can be expanded upward, and the toner capacity can be increased.

[0019] The process cartridge of the present disclosure includes the developing cartridge and a drum cartridge. The drum cartridge includes a photosensitive drum, a charger for charging the photosensitive drum, and a drum frame for holding the photosensitive drum and the charger. When the developing cartridge is in a usable state mounted on the housing of the image forming apparatus, the first part is positioned directly above the rotation axis center. When the developing cartridge is in a usable state, the second part is positioned opposite to the supply roller with respect to the rotation axis center in the horizontal direction. When the developing cartridge is in a usable state, the third part is positioned directly below the rotation axis center. When the developing cartridge is in a usable state, the upper end of the partition wall is positioned below the upper end of the supply roller. During the operation of the developing cartridge, the film rotates so as to contact the first part, the second part, and the third part in this order. During the operation of the developing cartridge, the film does not contact the supply roller.

[0020] When the developing cartridge is in a usable state, by configuring the upper end of the partition wall to be positioned below the upper end of the supply roller, the toner above the supply roller can easily return to the toner storage chamber, so the circulation of the toner in the developing cartridge can be improved. By configuring the film to contact the first part, the second part, and the third part of the inner wall, a large amount of toner in the toner storage chamber can be supplied onto the supply roller, so the circulation of the toner can be improved. By improving the circulation of the toner, the degree of deterioration of the toner can be made uniform.

[0021] The image forming apparatus of the present disclosure includes the process cartridge, a housing to which the process cartridge is detachably attached, a sheet tray for accommodating sheets, a pickup roller for feeding the sheets in the sheet tray toward the process cartridge, and a fixing device for fixing the toner image onto the sheet. Inside the housing, a motor for rotating a photosensitive drum, a developing roller, a supply roller, and an agitator is provided. When the developing cartridge is in a usable state attached to the housing of the image forming apparatus, the first portion is located directly above the rotation axis center. When the developing cartridge is in a usable state, the second portion is located on the opposite side of the rotation axis center from the supply roller in the horizontal direction. When the developing cartridge is in a usable state, the third portion is located directly below the rotation axis center. When the developing cartridge is in a usable state, the upper end of the partition wall is located below the upper end of the supply roller. During the operation of the developing cartridge, the film rotates so as to come into contact with the first portion, the second portion, and the third portion in this order. During the operation of the developing cartridge, the film does not contact the supply roller.

[0022] When the developing cartridge is in a usable state, by adopting a configuration in which the upper end of the partition wall is located below the upper end of the supply roller, the toner above the supply roller can easily return to the toner storage chamber, so that the circulation of the toner in the developing cartridge can be improved. By adopting a configuration in which the film contacts the first portion, the second portion, and the third portion of the inner wall, a large amount of toner in the toner storage chamber can be supplied onto the supply roller, so that the circulation of the toner can be improved. By improving the circulation of the toner, the degree of deterioration of the toner can be made uniform.

Advantages of the Invention

[0023] Since the circulation of the toner in the developing cartridge can be improved, the degree of deterioration of the toner can be made uniform.

Brief Description of the Drawings

[0024] [Figure 1]This is a diagram showing an image forming apparatus. [Figure 2] This figure shows an image forming apparatus with the process cartridge removed. [Figure 3] This is a magnified cross-sectional view showing the process cartridge mounted in the housing. [Figure 4] These are perspective views (a) and side views (b) showing the structure around the coupling gear of the developing cartridge. [Modes for carrying out the invention]

[0025] Next, embodiments will be described. As shown in Figure 1, the image forming apparatus 1 comprises a housing 2, a sheet supply unit 3, an exposure device 4, a process cartridge 5, and a fixing device 8. In this embodiment, the directions are those shown in Figure 1, etc. Specifically, the vertical direction when the housing 2 is installed on a horizontal floor surface is defined as the "up and down direction." The direction in which the drum shaft 61X extends is defined as the left and right direction. The direction perpendicular to the up and down direction and the left and right direction is defined as the front and back direction. In the front and back direction, the direction from the developing roller shaft 71X toward the agitator shaft 74X is defined as the "front," and the direction from the agitator shaft 74X toward the developing roller shaft 71X is defined as the "rear."

[0026] The sheet supply unit 3 is located at the bottom of the housing 2. The sheet supply unit 3 comprises a sheet tray 31, a pressing plate 32, and a sheet supply mechanism 33. The sheet tray 31 holds sheets S such as paper. The pressing plate 32 pushes the sheets S in the sheet tray 31 upward. The sheet supply mechanism 33 has a pickup roller 33A. The pickup roller 33A supplies the sheets S that have been pushed up by the pressing plate 32 in the sheet tray 31 toward the process cartridge 5.

[0027] The exposure device 4 is located above the sheet tray 31. The exposure device 4 includes a light source, a deflector, a lens, a mirror, and the like. The exposure device 4 emits a light beam as shown by the dashed line to expose the surface of the photosensitive drum 61.

[0028] The process cartridge 5 is located above the sheet supply mechanism 33. The process cartridge 5 comprises a drum cartridge 6 and a developer cartridge 7. The developer cartridge 7 is detachable from the drum cartridge 6.

[0029] The drum cartridge 6 comprises a photosensitive drum 61, a charger 62, a transfer roller 63, and a drum frame 65. The photosensitive drum 61 rotates clockwise in the diagram around a drum shaft 61X that extends in the left-right direction.

[0030] The charger 62 charges the surface of the photosensitive drum 61. The transfer roller 63 rotates counterclockwise around the transfer roller axis 63X, which extends in the left-right direction. The drum frame 65 holds the photosensitive drum 61, the charger 62, and the transfer roller 63.

[0031] The developing cartridge 7 comprises a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, an agitator 74, and a frame 75.

[0032] The developing roller 71 rotates counterclockwise around the developing roller shaft 71X, which extends in the left-right direction. The supply roller 72 rotates counterclockwise around the supply roller shaft 72X, which extends in the left-right direction. The supply roller 72 is in contact with the developing roller 71. The layer thickness regulating blade 73 regulates the thickness of the toner layer on the developing roller 71 to a constant thickness.

[0033] The frame 75 holds the developing roller 71, the supply roller 72, the layer thickness regulating blade 73, and the agitator 74. The frame 75 houses the supply roller 72 and the agitator 74. The frame 75 is capable of housing toner. Specifically, the frame 75 has a toner storage chamber 76 capable of housing toner.

[0034] The agitator 74 rotates clockwise in the diagram around the agitator shaft 74X, which extends in the left-right direction as the axis of rotation. By rotating, the agitator 74 agitates the toner in the toner storage chamber 76. The supply roller 72 supplies toner to the developing roller 71.

[0035] The fixing device 8 is located above the process cartridge 5. The fixing device 8 includes a heating roller 81 and a pressure roller 82. The heating roller 81 heats the sheet S. The pressure roller 82 sandwiches the sheet S between itself and the heating roller 81.

[0036] The image forming apparatus 1 charges the surface of the photosensitive drum 61 with the charger 62. Next, the image forming apparatus 1 exposes the charged surface of the photosensitive drum 61 with a light beam emitted from the exposure apparatus 4. This forms an electrostatic latent image on the photosensitive drum 61 based on the image data. Next, the image forming apparatus 1 supplies toner from the developing roller 71 to the photosensitive drum 61. This forms a toner image on the photosensitive drum 61.

[0037] Subsequently, the image forming apparatus 1 transports the sheet S supplied from the sheet supply unit 3 between the photosensitive drum 61 and the transfer roller 63. This transfers the toner image formed on the photosensitive drum 61 to the sheet S. After that, the image forming apparatus 1 transports the sheet S, on which the toner image has been transferred, between the heating roller 81 and the pressure roller 82. This allows the fixing device 8 to fix the toner image transferred to the sheet S.

[0038] The image forming apparatus 1 discharges the sheet S on which the toner image has been fixed into the discharge tray 2A using the discharge roller 9.

[0039] The housing 2 comprises a housing body 21 and a cover 22. The housing body 21 has an opening 21A. The cover 22 opens and closes the opening 21A. The cover 22 is movable relative to the housing body 21 between a closed position shown in Figure 1 and an open position shown in Figure 2. Specifically, the cover 22 is rotatable relative to the housing body 21 between the closed position and the open position. The closed position is the position in which the opening 21A is closed. The open position is the position in which the opening 21A is opened.

[0040] A motor M is installed inside the housing 2. The motor M rotates the photosensitive drum 61, the developing roller 71, the supply roller 72, and the agitator 74.

[0041] As shown in Figure 2, the process cartridge 5 is detachable from the housing 2. Specifically, the process cartridge 5 is detachable from the housing body 21 through the opening 21A when the cover 22 is in the open position.

[0042] As shown in Figure 3, the agitator 74 has a shaft 74A and a film 74B. The shaft 74A is made of resin or the like and is rotatably supported by the frame 75. Here, Figure 3 shows the developing cartridge 7 in a ready-to-use state, mounted in the housing 2. In the following description, unless otherwise specified, the positional relationships of each part are those when the developing cartridge 7 is ready to use.

[0043] The film 74B is elastically deformable. The film 74B is made of resin or the like. One end of the film 74B is fixed to the shaft 74A, and the other end is a free end. The other end of the film 74B can come into contact with the frame 75. The film 74B rotates around the agitator shaft 74X.

[0044] Frame 75 has an interior wall W1 and a partition wall W2. The inner wall W1 is a wall that forms the toner storage chamber 76. The inner wall W1 has a first wall W11, a second wall W12, a third wall W13, a fourth wall W14, and a plurality of ribs W15.

[0045] The first wall W11 is located above the agitator axis 74X. The first wall W11 extends in the front-to-back direction.

[0046] The second wall W12 extends diagonally downward and backward from the rear end of the first wall W11. The third wall W13 extends downward from the front end of the first wall W11.

[0047] The fourth wall W14 extends backward from the lower end W131 of the third wall W13. The fourth wall W14 is formed in a roughly arc shape that curves downward. The fourth wall W14 is separated from the second wall W12. The rear end W141 of the fourth wall W14 is located behind the second wall W12. The space between the lower end of the second wall W12 and the rear end W141 of the fourth wall W14 is an opening for the agitator 74 to send toner from the toner storage chamber 76 toward the supply roller 72.

[0048] Rib W15 connects the first wall W11 and the second wall W12. Multiple ribs W15 are arranged with spacing between them in the left-right direction. Rib W15 has an inner surface F1 that can contact the film 74B. The inner surface F1 is formed in an arc shape that is convex in the direction away from the agitator axis 74X.

[0049] Rib W15 has a first portion P1. The first portion P1 is located directly above the agitator axis 74X.

[0050] The third wall W13 has a second portion P2. The second portion P2 is located opposite the supply roller 72 with respect to the agitator shaft 74X in the horizontal direction, more specifically in the front-rear direction.

[0051] The fourth wall W14 has a third section P3. The third section P3 is located directly below the agitator axis 74X.

[0052] The partition wall W2 extends upward from a position below the supply roller 72. More specifically, the partition wall W2 extends from a position below the supply roller 72 along the outer circumferential surface of the supply roller 72 toward the rear end of the fourth wall W14. The partition wall W2 is connected to the rear end of the fourth wall W14.

[0053] The upper end W21 of the partition wall W2 is located between the supply roller 72 and the agitator 74. The upper end W21 of the partition wall W2 is located below the upper end 72A of the supply roller 72. More specifically, the upper end W21 of the partition wall W2 is located below the supply roller axis 72X, which is the rotation axis of the supply roller 72. The upper end W21 of the partition wall W2 is located outside the virtual rotation trajectory T of the leading edge of the undeformed film 74B.

[0054] The developing roller axis 71X, which is the rotation axis of the developing roller 71, is located above the supply roller axis 72X. The first part P1 is located above the upper end 71A of the developing roller 71. The agitator axis 74X is located above the supply roller axis 72X.

[0055] During the operation of the developing cartridge 7, the film 74B rotates so that it contacts the first part P1, the second part P2, and the third part P3 in that order. During the operation of the developing cartridge 7, the film 74B does not come into contact with the supply roller 72.

[0056] As shown in Figures 4(a) and 4(b), the developing cartridge 7 further comprises a coupling gear G1, a supply roller gear G2, a developing roller gear G3, an idler gear G4, and an agitator gear G5.

[0057] The coupling gear G1 is a gear having a coupling that receives driving force from the motor M. When the coupling gear G1 receives driving force from the motor M, it rotates clockwise as shown in the diagram.

[0058] The supply roller gear G2 is located at the end of the supply roller 72. The supply roller gear G2 is rotatable together with the supply roller 72 around the supply roller shaft 72X. The supply roller gear G2 meshes with the coupling gear G1.

[0059] The developing roller gear G3 is located at the end of the developing roller 71. The developing roller gear G3 is rotatable together with the developing roller 71 around the developing roller shaft 71X. The developing roller gear G3 meshes with the coupling gear G1.

[0060] The idler gear G4 is located between the coupling gear G1 and the agitator gear G5. The idler gear G4 is a two-stage gear with two gear teeth in the left-right direction, and each gear tooth meshes with the coupling gear G1 and the agitator gear G5. The idler gear G4 reduces the driving force from the coupling gear G1 and transmits it to the agitator gear G5.

[0061] The agitator gear G5 is located at the end of the agitator 74. The agitator gear G5 is rotatable together with the agitator 74 around the agitator shaft 74X.

[0062] The first gear ratio, which is the gear ratio of the agitator gear G5 to the coupling gear G1, is smaller than the second gear ratio, which is the gear ratio of the supply roller gear G2 to the coupling gear G1. Specifically, the first and second gear ratios are set so that the rotational speed of the agitator 74 is 25-40% of the rotational speed of the supply roller 72. Here, the rotational speed of the supply roller 72 can be, for example, 178 rpm, and the rotational speed of the agitator can be, for example, 57 rpm.

[0063] Next, we will explain the effects of the developing cartridge 7. As shown in Figure 4(b), when a driving force is input from the motor M to the coupling gear G1, the driving force is transmitted from the coupling gear G1 to the supply roller gear G2, causing the supply roller 72 to rotate. In addition, the driving force is transmitted from the coupling gear G1 to the developing roller gear G3, causing the developing roller 71 to rotate.

[0064] Furthermore, driving force is transmitted from the coupling gear G1 to the agitator gear G5 via the idler gear G4, causing the agitator 74 to rotate at a rotational speed of 25-40% of the rotational speed of the supply roller 72.

[0065] As shown in Figure 3, when the developing cartridge 7 is unused, the toner storage chamber 76 is filled with toner up to the full level LV1, which is above the lower end of the second wall W12. In other words, the full level LV1 is the position of the upper surface of the toner when the unused developing cartridge 7 is positioned for use and the upper surface of the toner inside the unused developing cartridge 7 is leveled horizontally. In this embodiment, the full level LV1 is above the upper end of the developing roller 71.

[0066] When the developer cartridge 7 reaches its usage limit, toner remains in the toner storage chamber 76 up to the empty level LV2, which is below the upper end W21 of the partition wall W2. In other words, the empty level LV2 is the position of the top surface of the toner when the developer cartridge 7, which has reached its usage limit, is returned to a usable position and the top surface of the toner inside the developer cartridge 7 is leveled horizontally. In this embodiment, the empty level LV2 is below the lower end of the supply roller 72. The usage limit of the developer cartridge 7 is the usage limit while maintaining print quality, and the image forming apparatus 1 determines that the developer cartridge 7 has reached its usage limit by measuring the amount of toner used, such as by counting the number of printed dots.

[0067] As shown in Figure 3, when the agitator 74 rotates, the film 74B rotates so that it contacts the first part P1, second part P2, and third part P3 of the inner wall W1 in that order, supplying toner to the supply roller 72 over the partition wall W2. In this embodiment, the rotation speed of the agitator 74 is set to a small speed of about 25-40% of the rotation speed of the supply roller 72. However, since the film 74B is long enough to contact all of the first part P1, second part P2, and third part P3, sufficient stirring capacity can be obtained when the toner is filled to the full level LV1, and even when the toner approaches the empty level LV2, an appropriate amount of toner can be supplied to the supply roller 72.

[0068] As described above, the following effects can be obtained according to this embodiment. When the developing cartridge 7 is ready for use, the upper end W21 of the partition wall W2 is positioned below the upper end 72A of the supply roller 72. This configuration makes it easier for toner on the supply roller 72 to return to the toner storage chamber 76, thereby improving the circulation of toner within the developing cartridge 7. The configuration in which the film 74B is in contact with the first part P1, second part P2, and third part P3 of the inner wall W1 allows a large amount of toner in the toner storage chamber 76 to be supplied onto the supply roller 72, thereby improving toner circulation. Improved toner circulation allows for a more uniform rate of toner degradation.

[0069] By setting the rotation speed of the agitator 74 to a speed sufficiently lower than the rotation speed of the supply roller 72, the deterioration of toner due to agitation by the agitator 74 can be suppressed.

[0070] When the developing cartridge 7 is ready for use, the upper end W21 of the partition wall W2 is positioned below the supply roller shaft 72X. This configuration makes it easier for the toner on the supply roller 72 to return to the toner storage chamber 76, thereby further improving toner circulation.

[0071] When the developing cartridge 7 is ready for use, the developing roller shaft 71X is positioned above the supply roller shaft 72X, thereby preventing toner from accumulating between the developing roller 71 and the supply roller 72.

[0072] When the developing cartridge 7 is ready for use, the first part P1 is positioned above the upper end 71A of the developing roller 71, which allows the toner storage chamber 76 to be expanded upwards, thereby increasing the toner capacity.

[0073] When the developing cartridge 7 is ready for use, the agitator shaft 74X is positioned above the supply roller shaft 72X, which allows the toner storage chamber 76 to be expanded upwards, thereby increasing the toner capacity.

[0074] This disclosure is not limited to the embodiments described above and can be used in various forms as illustrated below.

[0075] When the developing cartridge is in the usable state, the upper end of the partition wall may be located below the upper end of the supply roller and above the rotation axis of the supply roller.

[0076] The image forming apparatus is not limited to printers; it may also be a copier or a multifunction device, for example.

[0077] The elements described in the above embodiments and modifications may be implemented in any combination. [Explanation of symbols]

[0078] 1. Image forming apparatus 2 cabinets 7. Developing cartridge 71 Developing roller 72 supply rollers 72A top end 74 Agitator 74B film 74X Agitator Shaft 75 frames 76 Toner Storage Room P1 1st part P2 2nd part P3 3rd part W1 Inner wall W2 partition wall W21 top end

Claims

1. Developing roller and A supply roller that contacts the developing roller and supplies toner to the developing roller, Toner storage room and An agitator for stirring the toner in the toner storage chamber, comprising an agitator having an elastically deformable film that rotates around a rotation axis, A developing cartridge comprising: a frame housing the supply roller and the agitator, having an inner wall of the toner storage chamber, the frame having a partition wall extending upward from a position below the supply roller, with its upper end located between the supply roller and the agitator; When the developing cartridge is mounted in the housing of the image forming apparatus and is ready for use, the inner wall has a first portion located directly above the rotation axis, a second portion located horizontally opposite the supply roller to the rotation axis, and a third portion located directly below the rotation axis. When the developing cartridge is in the usable state, the upper end of the partition wall is positioned below the upper end of the supply roller. A developing cartridge characterized in that, during the operation of the developing cartridge, the film rotates so as to contact the first part, the second part, and the third part in that order, and does not come into contact with the supply roller.

2. The developing cartridge according to claim 1, characterized in that the rotation speed of the agitator is 25 to 40% of the rotation speed of the supply roller.

3. The developing cartridge according to claim 1, characterized in that the upper end of the partition wall is located outside the rotational trajectory of the leading edge of the film in an undeformed state.

4. The developing cartridge according to claim 1, characterized in that when the developing cartridge is in the usable state, the upper end of the partition wall is located below the rotation axis of the supply roller.

5. The developing cartridge according to claim 1, characterized in that when the developing cartridge is in the usable state, the rotation axis of the developing roller is located above the rotation axis of the supply roller.

6. The developing cartridge according to claim 1, characterized in that when the developing cartridge is in the usable state, the first portion is located above the upper end of the developing roller.

7. The developing cartridge according to claim 1, characterized in that when the developing cartridge is in the usable state, the rotation axis of the agitator is located above the rotation axis of the supply roller.

8. A process cartridge comprising a developing cartridge and a drum cartridge, The aforementioned developing cartridge is Developing roller and A supply roller that contacts the developing roller and supplies toner to the developing roller, Toner storage room and An agitator for stirring the toner in the toner storage chamber, comprising an agitator having an elastically deformable film that rotates around a rotation axis, The frame comprises a frame that houses the supply roller and the agitator, and has an inner wall of the toner storage chamber, and has a partition wall that extends upward from a position below the supply roller, with its upper end located between the supply roller and the agitator, The aforementioned drum cartridge is Photosensitive drum and A charger for charging the photosensitive drum, The system comprises a drum frame that holds the photosensitive drum and the charger, When the developing cartridge is mounted in the housing of the image forming apparatus and is ready for use, the inner wall has a first portion located directly above the rotation axis, a second portion located horizontally opposite the supply roller to the rotation axis, and a third portion located directly below the rotation axis. When the developing cartridge is in the usable state, the upper end of the partition wall is positioned below the upper end of the supply roller. A process cartridge characterized in that, during the operation of the developing cartridge, the film rotates so as to contact the first portion, the second portion, and the third portion in that order, and does not come into contact with the supply roller.

9. An image forming apparatus comprising: a process cartridge having a developing cartridge and a drum cartridge; a housing from which the process cartridge can be attached and detached; a sheet tray for holding sheets; a pickup roller for supplying sheets in the sheet tray toward the process cartridge; and a fixing device for fixing toner images onto sheets, The aforementioned developing cartridge is Developing roller and A supply roller that contacts the developing roller and supplies toner to the developing roller, Toner storage room and An agitator for stirring the toner in the toner storage chamber, comprising an agitator having an elastically deformable film that rotates around a rotation axis, The frame comprises a frame that houses the supply roller and the agitator, and has an inner wall of the toner storage chamber, and has a partition wall that extends upward from a position below the supply roller, with its upper end located between the supply roller and the agitator, The aforementioned drum cartridge is Photosensitive drum and A charger for charging the photosensitive drum, The system comprises a drum frame that holds the photosensitive drum and the charger, The housing is provided with a motor that rotates the photosensitive drum, the developing roller, the supply roller, and the agitator. When the developing cartridge is mounted in the housing of the image forming apparatus and is ready for use, the inner wall has a first portion located directly above the rotation axis, a second portion located horizontally opposite the supply roller to the rotation axis, and a third portion located directly below the rotation axis. When the developing cartridge is in the usable state, the upper end of the partition wall is positioned below the upper end of the supply roller. An image forming apparatus characterized in that, during the operation of the developing cartridge, the film rotates so as to contact the first portion, the second portion, and the third portion in that order, and does not come into contact with the supply roller.

Images