Image forming apparatus

Abstract

To reduce fogging.SOLUTION: An image forming apparatus comprises: a photoreceptor; a rotary that has storage frame bodies each provided with a storage unit and a reception opening, developing rollers, and supply rollers; and toner cartridges. The supply roller has a foam layer formed with foam material and forming an outer peripheral surface of the supply roller, and is arranged such that the foam layer is elastically deformed at a contact part of the supply roller and the developing roller. When an area surrounded by an outer peripheral surface of the developing roller, the outer peripheral surface of the supply roller, and a common tangent of the outer peripheral surface of the developing roller and the outer peripheral surface of the supply roller, the area being on the downstream side of the contact part with respect to a direction of rotation of the supply roller, is defined as a downstream area, while the rotary is in a developing posture, the downstream area is located below the reception opening and at least partially overlaps the reception opening when seen in a vertical direction.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus that forms an image on a recording material. [Background technology]

[0002] Patent Document 1 describes a rotary development type image forming apparatus that forms a color image by rotating a development rotary having multiple developers. It also describes that the development rotary can be fitted with detachable toner cartridges containing toner of a color corresponding to each developer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-183305 Summary of the Invention [Problem to be solved by the invention]

[0004] The toner contained in the rotary container deteriorates due to mechanical stress caused by being carried on the developing roller and rubbing against the developing blade, photosensitive drum, etc., resulting in a decrease in charging performance. If a large amount of toner with poor charging performance is present on the developing roller, there is a possibility that image defects (fog) will occur, in which the toner is developed in areas on the recording material where an image should not be formed (non-image forming areas).

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus capable of reducing fogging. [Means for solving the problem]

[0006] One aspect of the present invention is a toner cartridge comprising: a photosensitive body; a storage frame provided with a storage section for storing toner and a receiving opening communicating with the storage section; a rotatable rotary having a rotatable developing roller that carries toner and supplies it to the photosensitive body; and a rotatable supply roller that supplies the toner stored in the storage section to the developing roller; and a toner cartridge that stores toner therein and is detachable from the rotary, the toner cartridge having a discharge opening that communicates with the receiving opening, and configured so that toner discharged from the discharge opening is supplied to the storage section through the receiving opening, the supply roller having a foam layer formed of a foam material and forming an outer circumferential surface of the supply roller, and a toner cartridge having a foam layer formed of a foam material and forming an outer circumferential surface of the supply roller, the supply roller ... the foam layer is arranged so as to be elastically deformable, the rotary is capable of taking an exchange position that allows the toner cartridge to be attached and detached to the rotary, and a development position that allows the developing roller to supply toner to the photosensitive member, and when the downstream region is the region surrounded by the outer surface of the developing roller, the outer surface of the supply roller, and a common tangent to the outer surface of the developing roller and the outer surface of the supply roller, and the region downstream of the contact portion in the rotational direction of the supply roller, when the rotary is in the development position, the downstream region is located below the receiving opening and at least partially overlaps with the receiving opening when viewed vertically.

[0007] Another aspect of the present invention is a toner cartridge comprising: a photosensitive body; a storage frame provided with a storage section for storing toner and a receiving opening communicating with the storage section; a rotatable developing roller that carries toner and supplies it to the photosensitive body; a rotatable supply roller that supplies the toner stored in the storage section to the developing roller; and a guide member that is disposed in the storage section and guides the toner supplied to the storage section through the receiving opening; and a toner cartridge that stores toner therein and is detachable from the rotary, the toner cartridge having a discharge opening that communicates with the receiving opening and configured so that toner discharged from the discharge opening is supplied to the storage section through the receiving opening, the supply roller having a foam layer made of a foam material and forming an outer circumferential surface of the supply roller, and the foam layer is disposed so as to elastically deform at a contact portion between the supply roller and the developing roller. the rotary is capable of taking an exchange position that allows the toner cartridge to be attached and detached to the rotary, and a development position that allows the developing roller to supply toner to the photosensitive body; the guide member has a supported portion that is supported by the storage frame body, and a tip that is located inside the receiving opening when viewed in the direction of the receiving opening when the rotary is in the development position; and when the downstream region is an area surrounded by the outer surface of the developing roller, the outer surface of the supply roller, and a common tangent to the outer surface of the developing roller and the outer surface of the supply roller, and the area downstream of the contact portion in the rotational direction of the supply roller, when the rotary is in the development position, the downstream region is located below the tip of the guide member and overlaps with the tip of the guide member when viewed vertically. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an image forming apparatus capable of reducing fogging. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to a first embodiment. [Figure 2] FIG. 1 is a configuration diagram of an image forming apparatus according to a first embodiment. [Figure 3] 2 is a schematic diagram of a developing unit, a toner cartridge, and a tray according to the first embodiment. FIG. [Figure 4] 1A and 1B are cross-sectional views of an image forming apparatus according to a first embodiment. [Figure 5] FIG. 2 is a perspective view of a rotary body according to the first embodiment. [Figure 6] FIG. 2 is a cross-sectional view of a photosensitive drum, a developing unit, and a toner cartridge according to the first embodiment. [Figure 7] FIG. 2 is a cross-sectional view of a photosensitive drum, a developing unit, and a toner cartridge according to the first embodiment. [Figure 8] FIG. 10 is a cross-sectional view of a photosensitive drum, a developing unit, and a toner cartridge according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view of a photosensitive drum, a developing unit, and a toner cartridge according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] Example 1 An outline of an image forming apparatus 1 according to a first embodiment will be described using FIGS. 1 to 5. In the following description and in each drawing, the vertical direction when the image forming apparatus 1 is installed on a horizontal surface is defined as the Z direction. The direction intersecting the Z direction and the direction of a rotation axis 90C of a rotary body 90 (described later, the direction of the rotary's rotation axis) is defined as the Y direction. The direction intersecting both the Z direction and the Y direction is defined as the X direction. The X direction and the Y direction are preferably horizontal. Furthermore, the X direction, the Y direction, and the Z direction are preferably perpendicular to each other. Furthermore, as necessary, the directions of the arrows X, Y, and Z shown in each drawing will be represented as the +X side, the +Y side, and the +Z side, respectively, and the opposite sides will be represented as the -X side, the -Y side, and the -Z side, respectively.

[0012] (Overall configuration of image forming apparatus) First, we will explain the overall configuration of the image forming apparatus 1. The image forming apparatus 1 is a laser beam printer that forms an image on a sheet S by electrophotography. More specifically, the image forming apparatus 1 is a color laser beam printer equipped with four development units 50y, 50m, 50c, and 50k. As the sheet S, which is the recording material (recording medium), a variety of sheet materials of different sizes and materials can be used, including paper such as plain paper and cardboard, surface-treated sheet materials such as plastic film, cloth, and coated paper, and sheet materials of special shapes such as envelopes and index paper.

[0013] The schematic configuration and image forming operation of image forming apparatus 1 will be described with reference to Figures 1, 2, and 3. Figure 1 is a schematic diagram showing the cross-sectional configuration of image forming apparatus 1. Figure 2 is a diagram explaining the drive source of image forming apparatus 1. Figure 3 is a conceptual diagram showing the configuration for replenishing toner from toner cartridge 70 to developing unit 50.

[0014] 1, the image forming apparatus 1 includes an image forming apparatus main body (hereinafter referred to as the apparatus main body) 1A and toner cartridges 70y, 70m, 70c, and 70k that are detachably attached to the apparatus main body 1A. The apparatus main body 1A in this embodiment is the portion of the image forming apparatus 1 excluding the toner cartridges 70y, 70m, 70c, and 70k.

[0015] An apparatus main body 1A of the image forming apparatus 1 has a drum-shaped (cylindrical) electrophotographic photosensitive member (hereinafter referred to as photosensitive drum) 2 as an image carrier that carries an electrostatic latent image. Around the photosensitive drum 2, a charging roller 3, a scanner 4 as an exposure device, and a cleaning unit 6 are arranged.

[0016] The charging roller 3 is an example of a charging means or charging unit for uniformly charging the photosensitive drum 2. The scanner 4 is an example of an exposure means or exposure unit that irradiates the photosensitive drum 2 with laser light according to image information to expose it. By irradiating the charged photosensitive drum 2 with laser light, an electrostatic latent image is formed on the surface of the photosensitive drum 2. The cleaning unit 6 is an example of a cleaning means or cleaning section that removes toner remaining on the surface of the photosensitive drum 2.

[0017] Furthermore, the apparatus main body 1A has a sheet storage section 300, a pickup roller 310, a feed roller 311, a separation roller 312, a pair of conveying rollers 320, a secondary transfer roller 12, a fixing device 40, and an intermediate transfer unit 10. The pickup roller 310 is an example of a feeding means or a feeding unit that feeds the sheet S. The feed roller 311 and the separation roller 312 are examples of a separation conveying unit that separates and conveys the sheets S one by one by frictional force. The secondary transfer roller 12 is an example of a transfer means or a transfer unit that transfers an image from the intermediate transfer belt 10a to the sheet S.

[0018] The intermediate transfer unit 10 has an intermediate transfer belt 10a, a belt drive roller 10b, a tension roller 10c, a cleaning device 13, and a primary transfer roller 11. The intermediate transfer belt 10a is an example of an intermediate transfer body that carries an image transferred (primary transfer) from the photosensitive drum 2 and transports it to be transferred (secondary transfer) to a sheet S. The intermediate transfer belt 10a is stretched over the belt drive roller 10b and the tension roller 10c. The belt drive roller 10b is a drive member that is rotationally driven by a drive source to transport the intermediate transfer belt 10a.

[0019] The apparatus main body 1A also has a rotary main body (rotary, rotating body, developing device) 90 having developing units 50y, 50m, 50c, and 50k. As will be described later, in this embodiment, trays (support members) 80y, 80m, 80c, and 80k are attached to the rotary main body 90. Toner cartridges 70y, 70m, 70c, and 70k are removably attached to the trays 80y, 80m, 80c, and 80k.

[0020] In the following description, multiple components with similar functions may be distinguished by numbers. For example, one of the toner cartridges 70y, 70m, 70c, and 70k may be referred to as the first toner cartridge, one of the remaining three as the second toner cartridge, one of the remaining two as the third toner cartridge, and the last one as the fourth toner cartridge. Similarly, one of the trays 80y, 80m, 80c, and 80k may be referred to as the first tray, one of the remaining three as the second tray, one of the remaining two as the third tray, and the last one as the fourth tray. In other words, one of the trays 80y to 80k is an example of a first support member, another of the trays 80y to 80k is an example of a second support member, yet another of the trays 80y to 80k is an example of a third support member, and the last of the trays 80y to 80k is an example of a fourth support member. These numbering schemes are used merely for convenience and, in principle, can be interchanged as appropriate.

[0021] The developing units (first to fourth developing units) 50y, 50m, 50c, and 50k are examples of developing means or developing sections that develop (visualize) the electrostatic latent image formed on the photosensitive drum 2 into a toner image using toner of the corresponding color. The developing units 50y, 50m, 50c, and 50k develop the electrostatic latent image formed on the photosensitive drum 2 using yellow toner, magenta toner, cyan toner, or black toner, respectively. The developing units 50y, 50m, 50c, and 50k may be arranged in an order different from that shown in FIG. 1.

[0022] The developing unit 50y has a developing roller 51y, a supply roller 52y, and a developing blade. The developing roller 51y is a developer carrier that carries toner as a developer and rotates to supply the toner to the photosensitive drum 2. The supply roller 52y is a supply member that is arranged in contact with the developing roller 51y and supplies toner to the developing roller 51y. The developing blade is a regulating member that regulates the thickness of the toner layer carried by the developing roller 51y. The other developing units 50m, 50c, and 50k also have similar developing rollers 51m, 51c, and 51k, supply rollers 52m, 52c, and 52k, and developing blades.

[0023] Toner cartridges 70y, 70m, 70c, and 70k are mounted on the rotary body 90, corresponding to the developing units 50y, 50m, 50c, and 50k. The toner cartridges 70y, 70m, 70c, and 70k contain yellow toner, magenta toner, cyan toner, and black toner, respectively, to replenish the developing units 50y, 50m, 50c, and 50k. One of the four toner colors can be referred to as the first toner, one of the remaining three toner colors as the second toner, one of the remaining two toner colors as the third toner, and the last toner as the fourth toner. For example, black toner can be referred to as the first toner, and magenta toner as the second toner. These numbering schemes are used merely for convenience and can generally be interchanged as needed.

[0024] The rotary main body 90 has a rotary frame 90f that supports the developing units 50y, 50m, 50c, and 50k. The developing units 50y, 50m, 50c, and 50k are supported by the rotary frame 90f, which is a rotatable support body.

[0025] Trays 80y, 80m, 80c, and 80k are attached to the rotary body 90. The combination of the rotary body 90 and the trays 80y, 80m, 80c, and 80k can be called the rotary unit 90U. In other words, the rotary unit 90U has the rotary body 90 and the trays 80y, 80m, 80c, and 80k.

[0026] The toner cartridges 70y-70k are detachably held in the trays 80y-80k. As will be described later, the trays 80y-80k are supported so as to be slidable to the outside of the rotary main body 90. The combination of the rotary unit 90U and the toner cartridges 70y, 70m, 70c, and 70k can be called the rotary assembly 90A. In other words, The rotary assembly 90A includes a rotary unit 90U and toner cartridges 70y, 70m, 70c, and 70k.

[0027] As will be described later, the rotary body 90 is rotatable around a rotation axis (rotation center) 90C. The rotation axis 90C coincides with the rotation axes of the rotary frame 90f, the rotary unit 90U, and the rotary assembly 90A. The rotation axis 90C is also substantially parallel to the rotation axis (rotation center) of the photosensitive drum 2.

[0028] The rotary body 90 can rotate around the rotation axis 90C to assume a developing position in which any one of the developing rollers 51y, 51m, 51c, and 51k faces the photosensitive drum 2. The position in which the developing roller 51y faces the photosensitive drum 2 is called the yellow developing position. The position in which the developing roller 51m faces the photosensitive drum 2 is called the magenta developing position. The position in which the developing roller 51c faces the photosensitive drum 2 is called the cyan developing position. The position in which the developing roller 51k faces the photosensitive drum 2 is called the black developing position. In other words, the rotary body 90 can rotate around the rotation axis 90C so that the positions of the developing rollers 51y, 51m, 51c, and 51k relative to the photosensitive drum 2 change. The black developing position is an example of a first developing position in which the first developing roller (developing roller 51k) faces the photosensitive drum 2. The other developing positions are examples of the second developing position in which the second developing rollers (developing rollers 51y to 51c) face the photosensitive drum 2. The yellow / magenta / cyan / black developing positions can also be called the first to fourth developing positions. These numberings are used merely for convenience of explanation, and in principle can be interchanged as appropriate.

[0029] 2, the device main body 1A has motors M1, M2, and M3 as drive sources. As will be described later, the motor M1 supplies a drive force for rotating the rotary main body 90 about the rotation axis 90C. In other words, the motor M1 rotates the rotary assembly 90A and the rotary unit 90U about the rotation axis 90C.

[0030] The apparatus main body 1A also has a drive device 98 including a motor M2 and a transmission device. The transmission device includes drive racks 15L, 15R as drive gears, and a transmission unit 15t, which will be described later. The driving force of the motor M2 is transmitted to the drive racks 15L, 15R by the transmission unit 15t. In other words, the motor M2 is configured to drive the drive racks 15L, 15R, and moves the trays 80y, 80m, 80c, and 80k relative to the rotary main body 90 via the drive racks 15L, 15R.

[0031] Motor M3 drives components other than those driven by motors M1 and M2, such as the photosensitive drum 2, developing units 50y, 50m, 50c, and 50k, pickup roller 310, feed roller 311, conveying roller pair 320, secondary transfer roller 12, belt drive roller 10b, and fixing device 40.

[0032] The components driven by motors M1, M2, and M3 can be changed as needed. Also, the functions of any two or all three of motors M1, M2, and M3 can be combined into one motor. Alternatively, drive sources other than motors M1, M2, and M3 may be added.

[0033] Here, the suffixes y, m, c, and k attached to the developing units 50y, 50m, 50c, and 50k, the toner cartridges 70y, 70m, 70c, and 70k, and the trays 80y, 80m, 80c, and 80k indicate the toner colors. The developing units 50y, 50m, 50c, and 50k share the same basic configuration and function. The toner cartridges 70y, 70m, 70c, and 70k share the same basic configuration and function. The trays 80y, 80m, 80c, and 80k also share the same basic configuration and function. Therefore, when it is not necessary to distinguish between them, the suffixes y, m, c, and k are omitted, and the description will be given assuming that the unit is any one of the four units, cartridges, and trays.

[0034] 3, the toner cartridge 70 has a toner frame 71. The toner frame 71 has a toner storage section 71a that stores toner, and a discharge opening 71b that communicates with the toner storage section 71a.

[0035] The developing unit 50 has a developing frame (storage frame) 53. The developing frame 53 has a developing-side storage portion 53a and a receiving opening 53b that communicates with the developing-side storage portion (toner supply chamber) 53a. As mentioned above, the developing unit 50 has the developing roller 51, the supply roller 52, etc., but these members are omitted in Figure 3.

[0036] The developing roller 51k of the developing unit 50k is an example of a first developing roller. The developing roller 51m of the developing unit 50m is an example of a second developing roller. The developing frame 53k (FIG. 4(a)) of the developing unit 50k having the developing-side accommodating portion 53a is an example of a first accommodating frame having a first accommodating portion. The developing frame 53m (FIG. 4(a)) of the developing unit 50m having the developing-side accommodating portion 53a is an example of a second accommodating frame having a second accommodating portion. The rotary body 90 is an example of a rotatable rotary having a first developing roller, a second developing roller, a first accommodating frame having a first accommodating portion, and a second accommodating frame having a second accommodating portion. In this embodiment, the rotary body 90 has first to fourth developing rollers and first to fourth accommodating frames.

[0037] As will be described later, the toner cartridge 70 is movable between an attached position and a retracted position retracted from the attached position relative to the developing frame 53. When the toner cartridge 70 is in the attached position relative to the developing frame 53, the discharge opening 71b faces the receiving opening 53b. In other words, the toner storage portion 71a of the toner cartridge 70 and the developer-side storage portion 53a of the developing unit 50 communicate with each other via the discharge opening 71b and the receiving opening 53b. When toner is replenished from the toner cartridge 70 to the developing unit 50, at least a portion of the receiving opening 53b is positioned below at least a portion of the discharge opening 71b.

[0038] The toner contained in the toner container 71a is then discharged from the discharge opening 71b, and the toner discharged from the discharge opening 71b is received in the developer-side container 53a through the receiving opening 53b. The toner contained in the developer-side container 53a is supplied to the developing roller 51 by the supply roller 52. The toner contained in the toner container 71a is supplied to the developing roller 51 through this route.

[0039] The toner cartridge 70 preferably has a sealing member (first sealing member) (not shown) that covers the discharge opening 71b, and the developing unit 50 preferably has a sealing member (second sealing member) (not shown) that covers the receiving opening 53b.

[0040] When the toner cartridge 70 is not attached to the development unit 50, it is desirable that the discharge opening 71b and the receiving opening 53b are each covered with a sealing member so as to prevent toner from leaking out from the discharge opening 71b and the receiving opening 53b.

[0041] (Image formation operation) The image forming operation in this embodiment will be described. First, the photosensitive drum 2 is rotated in the direction of arrow R1 (counterclockwise) in FIG. 1 in synchronization with the rotation of the intermediate transfer belt 10a. Then, the surface of the photosensitive drum 2 is uniformly charged by the charging roller 3.

[0042] When a color image is formed on the sheet S, the rotary body 90 rotates in the direction of arrow R2 (clockwise) in Figure 1 while supporting the developing units 50y, 50m, 50c, and 50k, as follows: Then, the electrophotographic process is repeated while the developing rollers 51y, 51m, 51c, and 51k are moved one by one to the developing position.

[0043] First, the scanner 4 irradiates the photosensitive drum 2 with laser light based on image data corresponding to a yellow image, forming an electrostatic latent image corresponding to the yellow image on the surface of the photosensitive drum 2. In parallel with the formation of this electrostatic latent image, the motor M1 rotates the rotary body 90, causing the rotary body 90 to assume a yellow developing position. When the rotary body 90 is in the yellow developing position, the developing roller 51y is in the developing position, and develops the electrostatic latent image formed on the photosensitive drum 2 with yellow toner.

[0044] In this embodiment, each of the developing rollers 51y, 51m, 51c, and 51k is an elastic roller with a metal shaft covered with rubber. At the developing position, each of the developing rollers 51y, 51m, 51c, and 51k develops an electrostatic latent image while in contact with the photosensitive drum 2. In other words, the image forming apparatus 1 in this embodiment employs a contact development system. However, each of the developing rollers 51y, 51m, 51c, and 51k may also develop an electrostatic latent image while a gap is provided between the developing rollers 51y, 51m, 51c, and 51k and the photosensitive drum 2 at the developing position. In other words, the image forming apparatus 1 may employ a non-contact development system.

[0045] When the yellow toner image is developed, the yellow toner image on the photosensitive drum 2 is primarily transferred onto the intermediate transfer belt 10a by the primary transfer roller 11 arranged inside the intermediate transfer belt 10a.

[0046] Thereafter, the rotary body 90 is rotated to move the developing rollers 51m, 51c, and 51k to the developing positions in order, thereby forming toner images of each color. That is, after a yellow toner image is formed on the intermediate transfer belt 10a, the rotary body 90 assumes a magenta developing position, and a magenta toner image is formed on the intermediate transfer belt 10a. After a magenta toner image is formed on the intermediate transfer belt 10a, the rotary body 90 assumes a cyan developing position, and a cyan toner image is formed on the intermediate transfer belt 10a. After a cyan toner image is formed on the intermediate transfer belt 10a, the rotary body 90 assumes a black developing position, and a black toner image is formed on the intermediate transfer belt 10a. After a black toner image is formed on the intermediate transfer belt 10a, the rotary body 90 rotates around the rotation axis 90C in the direction of the arrow (clockwise) shown in FIG. 1 and returns to the yellow developing position. The color of the image formed first on the intermediate transfer belt 10a is arbitrary; for example, a black toner image may be formed first.

[0047] Then, the primary transfer is repeated so that the four color toner images are superimposed on the intermediate transfer belt 10a, thereby forming a color image on the intermediate transfer belt 10a. Note that, until the color image is formed on the intermediate transfer belt 10a, the secondary transfer roller 12 and the cleaning device 13 are not in contact with the intermediate transfer belt 10a.

[0048] Meanwhile, sheets S are fed by a pickup roller 310 from a sheet storage unit 300 provided at the bottom of the apparatus main body 1A. The sheets S are separated into individual sheets by a feed roller 311 and a separation roller 312 and then fed to a pair of conveying rollers 320. The pair of conveying rollers 320 sends the fed sheets S to a transfer unit (secondary transfer unit), which is a nip between the intermediate transfer belt 10a and the secondary transfer roller 12. The color image on the intermediate transfer belt 10a is transferred (secondary transfer) onto the surface of the conveyed sheet S.

[0049] The sheet S onto which the color image has been transferred is sent to the fixing device 40. In the fixing device 40, the sheet S is heated and pressurized, and the image is fixed onto the sheet S. After passing through the fixing device 40, the sheet S is discharged outside the image forming apparatus 1 as a finished product.

[0050] On the other hand, when a monochrome image is formed on the sheet S, the rotary body 90 takes the black developing position. In this state, an electrostatic latent image is formed on the surface of the photosensitive drum 2 by charging and exposing the photosensitive drum 2, and then the electrostatic latent image is developed with black toner by the developing roller 51k positioned at the developing position. The black toner image is primarily transferred to the intermediate transfer belt 10a, and then secondarily transferred to the sheet S. The subsequent steps are the same as those for color images.

[0051] (Rotary configuration) The configuration of the rotary body 90 will be described using Figures 1, 4(a, b), and 5. Figures 4(a, b) are cross-sectional views showing the rotary body 90 and its surroundings of the image forming apparatus 1. Figures 4(a, b) are cross-sectional views of the apparatus cut along an imaginary plane perpendicular to the rotation axis 90C of the rotary body 90. Figure 5 is a perspective view of the rotary body 90.

[0052] As described above, the toner cartridges 70y to 70k are detachable from the rotary body 90. When the toner in the toner cartridges 70y to 70k runs out, the user can replenish toner in the image forming apparatus 1 by replacing the toner cartridges 70y to 70k with new ones.

[0053] 1, the apparatus main body 1A has a frame 16 that houses the rotary main body 90. The frame 16 is the main body frame of the image forming apparatus 1 of this embodiment. The frame 16 is the housing (skeleton) of the apparatus main body 1A that is composed of a frame and exterior members, and is approximately rectangular in shape in this embodiment.

[0054] The frame 16 has an opening 16a. More specifically, the frame 16 has a side surface 16b that extends in a direction intersecting the horizontal direction. The side surface 16b constitutes at least a part of the exterior surface on the +X side of the device main body 1A. The opening 16a is located on this side surface 16b. The side surface 16b is located downstream of the discharge port in the discharge direction in which the sheets S on which images are formed are discharged from the discharge port of the device main body 1A. A user can access the sheet storage unit 300 from the side surface 16b of the image forming apparatus 1 to refill the sheets S or retrieve the sheets S discharged from the discharge port. Therefore, the side surface 16b can be said to be the front surface (front face) of the device main body 1A.

[0055] Toner cartridges 70y, 70m, 70c, and 70k are detachably attached to the rotary body 90 through the opening 16a. In other words, toner cartridge 70k is an example of a first toner cartridge that contains toner to be supplied to the first developing roller (developing roller 51k) and is detachably attached to the rotary (rotary body 90) through the opening 16a of the frame 16 of the apparatus main body 1A. Toner cartridge 70m is an example of a second toner cartridge that contains toner to be supplied to the second developing roller (developing roller 51m) and is detachably attached to the rotary (rotary body 90) through the opening 16a of the frame 16 of the apparatus main body 1A.

[0056] In this embodiment, the toner cartridges 70y, 70m, 70c, and 70k are supported by the trays 80y to 80k and are attached to and detached from the rotary body 90 through the opening 16a. In other words, the user can attach and detach the toner cartridges 70y to 70k to and from the rotary body 90 via the trays 80y to 80k.

[0057] The opening 16a is disposed on a side surface 16b of the frame body 16. In this embodiment, the side surface 16b is a surface that is approximately parallel to the rotation axis 90C of the rotary body 90. Therefore, when the toner cartridge 70 is replaced, the toner cartridge 70 passes through the opening 16a in a direction intersecting (preferably perpendicular to) the rotation axis 90C.

[0058] The image forming apparatus 1 has a door 14 that covers the opening 16a of the frame 16. The door 14 is an openable / closable member that can be moved between a closed position that covers the opening 16a and an open position that exposes the opening 16a.

[0059] As described above, in this embodiment, the toner cartridge 70 is configured to be detachable from the rotary body 90 via the tray 80. Therefore, the toner cartridge 70 can be detachable from the rotary body 90 in a stable manner.

[0060] More specifically, the user can replace the toner cartridge 70 by inserting or removing the toner cartridge 70 into or from the tray 80, which is configured to be movable relative to the rotary body 90 (i.e., relative to the device main body 1A). In a configuration in which the user replaces the toner cartridge by directly inserting or removing the toner cartridge into or from the device main body, the user is required to insert the toner cartridge to a predetermined installation position within the device main body. In this embodiment, the tray 80 is movable so that the toner cartridge 70 moves to the installation position while supporting the toner cartridge 70. Therefore, the user can replace the toner cartridge 70 by simply placing the toner cartridge 70 on the tray 80, improving operability.

[0061] The toner cartridge 70 has an elongated shape with its longitudinal direction being the Y direction parallel to the rotation axis 90C of the rotary body 90. In other words, the longitudinal dimension of the toner cartridge 70 is greater than the height and width of a cross section perpendicular to the longitudinal direction. When handling such an elongated toner cartridge 70, by locating the opening 16a on the side surface 16b of the frame 16 that is approximately parallel to the longitudinal direction (Y direction) of the toner cartridge 70, the toner cartridge 70 can pass through the opening 16a with a short movement distance. For example, this makes it easier to replace the toner cartridge 70 than when inserting or removing the toner cartridge 70 through an opening provided on the side surface of either side (+Y side or −Y side) of the frame 16 in the longitudinal direction of the toner cartridge 70.

[0062] The rotary body 90 can rotate around a rotation axis 90C and assume replacement positions that allow removal of any of the toner cartridges 70y to 70k from the rotary body 90. The position that allows removal of toner cartridge 70y is called the yellow replacement position. The position that allows removal of toner cartridge 70m is called the magenta replacement position. The position that allows removal of toner cartridge 70c is called the cyan replacement position. The position that allows removal of toner cartridge 70k is called the black replacement position. The black replacement position is an example of a first replacement position that allows removal of the first toner cartridge from the rotary body 90. The yellow / magenta / cyan replacement position is an example of a second replacement position that allows removal of the second toner cartridge from the rotary body 90. The yellow / magenta / cyan / black replacement positions can also be called the first to fourth replacement positions. These numberings are used merely for convenience of explanation and can, in principle, be interchanged as appropriate.

[0063] The rotary body 90 rotates clockwise in FIG. 1 around the rotation axis 90C, and can sequentially assume yellow, magenta, cyan, and black replacement positions. In this embodiment, the rotary body 90 alternates between the development position and the replacement position by rotating clockwise in FIG. 1 around the rotation axis 90C. For example, in FIG. 1, the rotary body 90 is in the black development position. From this state, by rotating the rotary body 90 clockwise, the rotary body 90 switches its position in the following order: cyan replacement position, yellow development position, black replacement position, magenta development position, yellow replacement position, cyan development position, and magenta replacement position. By rotating the rotary body 90 clockwise from the magenta replacement position, the rotary body 90 returns to the black development position. In other words, the rotary body 90 can rotate clockwise one revolution (360°) or more.

[0064] 4(a) shows a cross section of the rotary body 90 in a developing position (specifically, a yellow developing position), and FIG. 4(b) shows a cross section of the rotary body 90 in a replacement position (specifically, a black replacement position).

[0065] As shown in Figures 4(a) and 4(b), four trays 80y to 80k are attached to the rotary main body 90. The trays 80y to 80k hold the toner cartridges 70y to 70k, respectively. In Figures 4(a) and 4(b), the trays 80y to 80k are housed inside the rotary main body 90, which can be said to be the state in which the toner cartridges 70y to 70k are attached to the development units 50y, 50m, 50c, and 50k.

[0066] As described above, the toner cartridge 70 is movable between an attached position and a retracted position retracted from the attached position relative to the developing frame 53 of the developing unit 50. That is, the first toner cartridge (toner cartridge 70k) is movable between a first attached position and a first retracted position relative to the first accommodating frame (developing frame 53k). The second toner cartridge (toner cartridge 70m) is movable between a second attached position and a second retracted position relative to the second accommodating frame (developing frame 53m).

[0067] When the toner cartridge 70 is in the mounting position relative to the developing frame 53, the discharge opening 71b and the receiving opening 53b face each other, as shown in Fig. 3. In this state, the toner cartridge 70 is configured to supply toner to the developing-side accommodating portion 53a through the receiving opening 53b (the opening in the accommodating frame).

[0068] The apparatus main body 1A has a moving device 85 configured to move the toner cartridge 70 from an attached position to a retracted position relative to the rotary main body 90 (more specifically, relative to the developing frame 53 of the developing unit 50). In this embodiment, a plurality of moving devices 85y-85k corresponding to the plurality of toner cartridges 70y-70k are arranged in the rotary main body 90. It can be said that the trays 80y-80k are part of these moving devices 85y-85k.

[0069] Here, the rotational drive of the rotary body 90 will be described with reference to Figure 5. As shown in Figure 5, disk gears 92L and 92R are formed at both ends of the rotary body 90. Furthermore, rotary drive gears 93L and 93R are connected to both ends of the oscillating shaft 91 so as to be capable of transmitting drive power. Here, the drive force of the motor M1 is transmitted to the rotary drive gear 93R by a drive transmission mechanism. Next, the drive force is transmitted to the disk gears 92L and 92R by the rotary drive gears 93L and 93R, thereby rotating the rotary body 90. The rotary body 90 rotates clockwise in Figure 1 around a rotation axis 90C.

[0070] The rotary body 90 is supported so as to be able to swing about a swing shaft 91. The rotary body 90 is urged by a biasing member (not shown) in the counterclockwise direction in FIGS. 4(a) and 4(b) about the swing shaft 91. This direction can be said to be the direction in which each of the developing rollers 51y to 51k approaches the photosensitive drum 2. As a result, when the rotary body 90 is in the developing position, each of the developing rollers 51y to 51k comes into contact with the photosensitive drum 2.

[0071] 5, rotary cams 90eL and 90eR are provided at both ends of the rotary body 90. When the rotary body 90 rotates clockwise in FIGS. 4(a) and 4(b) around the rotation axis 90C, the rotary cams 90eL and 90eR come into contact with a roller 96 (FIGS. 4(a) and 4(b)) supported by the frame 16. Then, the rotary cams 90eL and 90eR move clockwise in FIGS. 4(a) and 4(b) around the swing shaft 91. This direction can be said to be the direction in which each of the developing rollers 51y to 51k moves away from the photosensitive drum 2. This direction can also be said to be the direction in which the rotary body 90 approaches the opening 16a of the frame 16 and the door 14.

[0072] As a result, when the rotary body 90 rotates and switches from the developing position to the replacement position, the rotary body 90 swings around the swing shaft 91. When the rotary body 90 is in the replacement position, the developing roller 51 is separated from the photosensitive drum 2.

[0073] 4(b), in the black replacement position, the toner cartridge 70k stops at a position facing the opening 16a provided in the side surface 16b of the apparatus main body 1A and the door 14. From this state, when the tray 80k is slid from the attachment position to the developing unit 50k to the outside of the rotary main body 90, the user can replace the toner cartridge 70k.

[0074] (Configuration of the development unit) Next, the developing unit 50 according to this embodiment will be described in detail with reference to Fig. 6. Fig. 6 is a cross-sectional view showing the photosensitive drum 2 according to this embodiment, the developing unit 50 (any one of the developing units 50y, 50m, 50c, and 50k), and the toner cartridge 70 corresponding to the developing unit 50.

[0075] Figure 6 shows a state in which the rotary body 90 is in a developing position that allows development by the illustrated developing unit 50. In the following description of Figures 6 to 9, unless otherwise specified, "a state in which the rotary body 90 is in a developing position" refers to a state in which the rotary body 90 is in a developing position that allows development by the illustrated developing unit 50. For example, if the developing unit 50 shown in Figures 6 to 9 is a yellow developing unit 50y, "a state in which the rotary body 90 is in a developing position" refers to a state in which the rotary body 90 is in a yellow developing position.

[0076] As shown in FIG. 6, the developing unit 50 includes a developing frame 53 as a frame of the developing unit 50, a developing roller 51, a supply roller 52, and a developing blade .

[0077] The developing roller 51 has a core 511, a base layer 512 formed on the outer periphery of the core 511, and a surface layer 513 formed on the outer periphery of the base layer 512. The core 511 is a cylindrical member with a diameter of 6 mm made of metal such as aluminum, aluminum alloy, or stainless steel. The base layer 512 and the surface layer 513 form a conductive elastic layer. That is, in this embodiment, the elastic layer has a multilayer structure in which multiple layers made of different materials are stacked. The developing roller 51 is formed to have an outer diameter of 10 mm.

[0078] The base layer 512 is formed of a rubber material such as butadiene acrylonitrile rubber (NBR), ethylene-propylene-diene polyethylene (EPDM), silicone rubber, or urethane rubber. The surface layer 513 is formed of a material such as ether urethane or nylon. The materials for each layer of the developing roller 51 are not limited to these. The base layer 512 may be formed of a foam such as sponge, and the surface layer 513 may be formed of a rubber material. The elastic layer may also have a single-layer structure formed of a rubber material such as NBR, EPDM, or urethane rubber.

[0079] When the rotary body 90 is in the development position, the development roller 51 faces the photosensitive drum 2 at the development unit Da. Since this embodiment uses a contact development system, the surface (outer peripheral surface 51s) of the development roller 51 comes into contact with the surface 2s of the photosensitive drum 2 at the development unit Da. The development roller 51 is also driven to rotate in the direction of arrow R3 in FIG. 6 by a driving force transmitted from a motor M3 (FIG. 2).

[0080] When the rotary body 90 is in the development posture, the rotation angle ra of the development unit Da around the rotation axis of the development roller 51 is between 270° and 360°, and in this embodiment, ra = 285°. However, the rotation angle ra represents the rotation angle to the development unit Da in the rotation direction of the development roller 51 (direction of arrow R3), with the vertical upward direction (+z direction) relative to the rotation axis of the development roller 51 as the reference (0°).

[0081] The developing roller 51 rotates around a rotation axis that is substantially parallel to the rotation axis 90C of the rotary body 90. The direction of the rotation axis of the developing roller 51 is referred to as the longitudinal direction of the developing roller 51, or simply as the longitudinal direction.

[0082] The developing roller 51 of this embodiment is disposed so as to intrude into the outer peripheral surface of the photosensitive drum 2. In other words, the rotational axis of the developing roller 51 is closer to the rotational axis of the photosensitive drum 2 than the position of the rotational axis of the developing roller 51 when the outer peripheral surfaces of the developing roller 51 and the photosensitive drum 2 come into contact, assuming that the developing roller 51 is a rigid body. The distance between the rotational axis of the developing roller 51 when it is assumed that the developing roller 51 is a rigid body and the actual rotational axis of the developing roller 51 is defined as the intrusion amount of the developing roller 51 into the photosensitive drum 2.

[0083] Push-in amount regulating rollers are arranged at both longitudinal ends of the developing roller 51. The push-in amount regulating rollers are supported by a core metal 511 and arranged to abut against the photosensitive drum 2. The abutment of the push-in amount regulating rollers with the photosensitive drum 2 regulates the amount of push-in of the developing roller 51 into the photosensitive drum 2 to a predetermined value.

[0084] A developing voltage (developing bias) is applied to the core metal 511 of the developing roller 51 from a developing voltage application circuit provided on a high-voltage board of the apparatus main body 1A. When the normal charging polarity of the toner is negative, the potential of the developing roller 51 to which the developing voltage is applied (developing potential) becomes negative with respect to the exposed area (light area potential) on the photosensitive drum 2, and positive with respect to the potential of the non-exposed area (dark area potential) on the photosensitive drum 2.

[0085] The developing blade 54 is disposed so as to be located below the developing roller 51 when the rotary body 90 is in the developing position. One end (fixed end) of the developing blade 54 is supported by a pressing plate 541, and the tip, which is the free end, is configured to abut against the outer peripheral surface 51s of the developing roller 51. The pressing plate 541 is a support member for the developing blade 54, and is fixed to the developing frame 53.

[0086] Here, the area where the developing roller 51 and the developing blade 54 come into contact is referred to as a regulating portion Db. The developing blade 54 regulates the thickness of the toner on the developing roller 51 at the regulating portion Db and also applies an electric charge to the toner on the developing roller 51. The contact direction of the developing blade 54 is a direction (so-called counter direction) that moves upstream in the rotation direction (direction of arrow R3) of the developing roller 51 as it approaches the free end from the fixed end.

[0087] The developing blade 54 can be suitably made of a spring-elastic metal thin plate such as a stainless steel thin plate or a phosphor bronze thin plate. The tip of the developing blade 54 abuts against the outer circumferential surface of the developing roller 51 with a predetermined linear pressure. A blade voltage (blade bias) is applied to the pressing plate 541 from a blade voltage application circuit provided on a high-voltage board of the apparatus main body 1A so as to create a predetermined potential difference with respect to the developing roller 51. In this embodiment, the normal charging polarity of the toner is negative, and in this case, the blade voltage is set so that the potential of the developing blade 54 is more negative than the development potential.

[0088] In this embodiment, the developing blade 54 is made of a 0.1 mm thick stainless steel plate with spring elasticity, and a blade voltage of -200 V relative to the development potential is applied. The configuration of the developing blade 54 is not limited to this. For example, a polyamide elastomer elastic member may be bonded or injection-molded to the tip of a spring elastic metal plate, and the elastic member may be pressed against the outer surface of the developing roller 51 with a predetermined linear pressure. In this case, the metal plate can maintain the pressure of the developing blade 54 against the developing roller 51. Furthermore, if the toner is, for example, a negatively charged toner, the friction of the polyamide elastomer at the tip can impart a negative charge to the toner. The metal plate is not particularly limited as long as it maintains the pressure of the developing blade 54. The elastic member can also be selected taking into account the toner's chargeability. To further improve charging performance, the elastic member may be made conductive and used in combination with the blade voltage.

[0089] In this embodiment, a toner having a particle diameter of 6 μm and a normal negative charge polarity is used as the developer. The toner may be, for example, a polymerized toner produced by a polymerization method. The toner in this embodiment does not contain a magnetic component and is a so-called non-magnetic single-component developer that is supported on the developing roller 51 mainly by intermolecular forces and electrostatic forces (image forces). However, a single-component developer containing a magnetic component may also be used as the toner. The single-component developer may also contain additives (e.g., wax or silica particles) in addition to the toner particles to adjust the fluidity and charging performance of the toner. A two-component developer composed of a non-magnetic toner and a magnetic carrier may also be used as the developer. When a magnetic developer is used, a cylindrical developing roller (developing sleeve) with a magnet disposed inside is used as the developer carrier.

[0090] The toner carried on the developing roller 51, with its thickness regulated by the developing blade 54, is transported to the developing unit Da by the rotation of the developing roller 51 and supplied to the photosensitive drum 2 for development. In order to obtain a toner image with a more appropriate image density, the circumferential speed of the developing roller 51 may be set to a speed different from that of the photosensitive drum 2. The circumferential speed of the developing roller 51 is preferably set to a value within a range such that the ratio of the circumferential speed of the developing roller 51 to that of the photosensitive drum 2 is 0.5 to 3.0, for example. In this embodiment, the circumferential speed of the developing roller 51 is set to a value 1.5 times that of the circumferential speed of the photosensitive drum 2.

[0091] The supply roller 52 is disposed so as to come into contact with the developing roller 51 at the contact portion Dc. The supply roller 52 supplies toner to the developing roller 51 at the contact portion Dc, and also collects from the developing roller 51 toner that is not used in development and remains on the developing roller 51 (residual toner after development).

[0092] The supply roller 52 has a foam layer 522 (sponge layer, foam elastic layer) made of a foam material and forming an outer peripheral surface 52s of the supply roller 52. The supply roller 52 is arranged so that the foam layer 522 elastically deforms at a contact portion Dc where the supply roller 52 and the developing roller 51 contact each other. In other words, the supply roller 52 is arranged so that it intrudes into the developing roller 51. That is, assuming that the developing roller 51 and the supply roller 52 do not elastically deform (i.e., are rigid bodies), the distance between the rotational axis of the developing roller 51 and the rotational axis of the supply roller 52 when the outer peripheral surfaces of the developing roller 51 and the supply roller 52 contact each other is defined as a first distance. The actual distance between the rotational axis of the developing roller 51 and the rotational axis of the supply roller 52 is defined as a second distance. In this case, the supply roller 52 is arranged so that the second distance is shorter than the first distance. The difference between the first distance and the second distance is defined as the intrusion amount of the supply roller 52 into the developing roller 51. The first distance is equal to the sum of the radius of the developing roller 51 and the radius of the supply roller 52 in their natural state (undeformed state).

[0093] From the viewpoint of the performance of supplying toner to the developing roller 51 and scraping off residual toner after development, it is preferable that the supply roller 52 be positioned so that the amount of penetration into the developing roller 51 is 0.1 mm or more and 1.5 mm or less. In this embodiment, the amount of penetration of the supply roller 52 into the developing roller 51 is set to 1.0 mm.

[0094] The supply roller 52 rotates in a rotational direction (counter direction, i.e., the direction of arrow R4) in which it rubs against the developing roller 51 at the contact point Dc. In other words, the movement direction of the outer peripheral surface 51s of the developing roller 51 at the contact point Dc between the developing roller 51 and the supply roller 52 is opposite to the movement direction of the outer peripheral surface 52s of the supply roller 52 at the contact point Dc. This allows toner to be efficiently scraped off from the developing roller 51 in an area C downstream of the contact point Dc in the rotational direction (R4) of the supply roller 52. In this embodiment, the peripheral speed of the supply roller 52 is set to 75% of the peripheral speed of the developing roller 51.

[0095] The foam constituting foam layer 522 can be one with a closed-cell structure in which the internal cells are independent, or one with an open-cell structure in which the internal cells are interconnected. Using a foam with an open-cell structure is more preferable because it allows a larger amount of toner to be stored inside foam layer 522 and ensures a stable supply of toner.

[0096] Supply roller 52 of this embodiment has metal core 521 with a diameter of 5 mm, and foam layer 522 formed on the outer periphery of core 521 so that the outer diameter of supply roller 52 is 11 mm. Foam layer 522 is formed of polyurethane foam with an open-cell structure having an average cell size (diameter) of 10 μm or more and 800 μm or less, and is made conductive by dispersing a conductive agent such as carbon in the foam material.

[0097] Furthermore, a supply roller voltage (supply roller bias) is applied to the core metal of supply roller 52 from a supply voltage application circuit provided on the high-voltage board of the apparatus main body 1A so as to create a predetermined potential difference with respect to developing roller 51. In this embodiment, the normal charging polarity of toner is negative, and in this case, the supply roller voltage is set so that the potential of supply roller 52 is more negative than the developing potential (for example, −200 V with the developing potential as the reference).

[0098] As the supply roller 52, instead of a roller (foam roller) having the foam layer 522, a roller having a fur brush structure in which fibers such as rayon or nylon are implanted on the core metal 521 can also be used.

[0099] (Toner supply configuration) Next, the toner supply path to the developing roller 51 in this embodiment will be described with reference to Figure 7. Figure 7 is a cross-sectional view of the developing unit 50, photosensitive drum 2, and toner cartridge 70 when the rotary body 90 is in the developing position, and shows the movement of toner supplied from the toner cartridge 70.

[0100] In FIG. 7, L1 is a common tangent to the outer peripheral surface 51s of the developing roller 51 and the outer peripheral surface 52s of the supply roller 52, the common tangent passing above the contact point Dc in the vertical direction. P51 is the point of contact between the common tangent L1 and the developing roller 51. P52 is the point of contact between the common tangent L1 and the supply roller 52. Region C is an area (hatched area) surrounded by the common tangent L1, the outer peripheral surface 51s of the developing roller 51, and the outer peripheral surface 52s of the supply roller 52, and is located downstream of the contact point Dc in the rotation direction (R4) of the supply roller 52. Region C is a substantially triangular area with vertices at the points of contact P51, P52, and the end points of the contact point Dc. Region C can be called a downstream region or a take-in region. Region C is also an area formed above the contact point Dc in the vertical direction when the rotary body 90 is in the development posture.

[0101] As described above, the discharge opening 71b faces the receiving opening 53b when the toner cartridge 70 is in the mounted position relative to the developing frame 53. In other words, the toner accommodating portion 71a of the toner cartridge 70 and the developing-side accommodating portion 53a of the developing unit 50 communicate with each other via the discharge opening 71b and the receiving opening 53b.

[0102] The toner cartridge 70 of this embodiment does not have a discharge means (screw, pump, etc.) for discharging the toner contained in the toner storage portion 71a to the outside, but is configured to discharge the toner by gravity. Therefore, when the opening direction of the discharge opening 71b is facing downward (-Z side) in the vertical direction, the toner in the toner storage portion 71a is discharged to the outside of the toner cartridge 70 through the discharge opening 71b. However, the configuration of this embodiment may be combined with a toner cartridge 70 that has a discharge means.

[0103] When the rotary body 90 is in the replacement position, the opening direction of the receiving opening 53b of the developing unit 50 faces downward in the vertical direction, and the opening direction of the discharge opening 71b of the toner cartridge 70 faces upward in the vertical direction. In other words, when the rotary body 90 is in the replacement position, the opening direction of the receiving opening 53b includes a component in the -Z direction, and the opening direction of the discharge opening 71b includes a component in the +Z direction. Therefore, when the rotary body 90 is in the replacement position, toner is not discharged from the toner cartridge 70 through the discharge opening 71b.

[0104] Here, the opening direction of the receiving opening 53b is a direction perpendicular to the outer surface of the developing frame 53 at the portion where the receiving opening 53b is provided, and is a direction from the inside to the outside of the developer-side accommodating portion 53a through the receiving opening 53b. Furthermore, the opening direction of the discharge opening 71b is a direction perpendicular to the outer surface of the toner cartridge 70 at the portion where the discharge opening 71b is provided, and is a direction from the inside to the outside of the toner accommodating portion 71a through the discharge opening 71b. Furthermore, when the rotary body 90 is in the replacement position, the opening directions of the receiving opening 53b and the discharge opening 71b may be inclined with respect to the vertical direction.

[0105] When the rotary body 90 is in the developing position, the receiving opening 53b of the developing unit 50 faces vertically upward, and the discharge opening 71b of the toner cartridge 70 faces vertically downward. Therefore, in the developing position, toner is discharged from the toner cartridge 70 through the discharge opening 71b, and further flows into the developing-side accommodating portion 53a through the receiving opening 53b.

[0106] The toner cartridge 70 of this embodiment discharges toner even when the opening direction of the discharge opening 71b faces vertically downward (-Z direction), but also discharges toner when the opening direction of the discharge opening 71b is tilted relative to the vertical direction, as shown in Figure 7. This is because even when the opening direction of the discharge opening 71b faces vertically downward, some toner remains in the toner storage section 71a without being discharged from the toner cartridge 70. When the rotary body 90 then rotates to the development position, the toner accumulated in the area 71a1 near the discharge opening 71b breaks down and falls from the discharge opening 71b, and flows into the development-side storage section 53a through the receiving opening 53b.

[0107] Here, the receiving opening 53b may be provided over the entire area of ​​the developing frame 53 in the longitudinal direction (Y direction), or may be provided only in a partial area. In this embodiment, the receiving openings 53b (first and second receiving openings) are provided at two locations, one at each end of the developing frame 53 in the longitudinal direction (Y direction). In other words, the developing frame 53 (storage frame) has a first receiving opening and a second receiving opening that communicate with the developing-side accommodating portion 53a (accommodating portion) and receive toner from the toner cartridge 70. The first receiving opening is located on one side of the center of the developing-side accommodating portion 53a in the direction of the rotary axis, and the second receiving opening is located on the other side of the center of the accommodating portion in the direction of the rotation axis. This makes it possible to prevent toner supplied from the toner cartridge 70 from being biased in the longitudinal direction inside the developing-side accommodating portion 53a.

[0108] The toner contained in the developer-side container 53a is supplied to the developing roller 51 by the supply roller 52. In this embodiment, the supply roller 52 contacts the developing roller 51 at the contact portion Dc with a predetermined penetration amount, and the cells of the foam layer 522 are collapsed at the contact portion Dc due to elastic deformation of the foam layer 522. As the supply roller 52 rotates, the collapsed cells move downstream of the contact portion Dc in the rotation direction (R4) of the supply roller 52, and the cell shape recovers, increasing its volume. As the cell shape recovers, the toner in region C is taken into the cells, and the toner on the developing roller 51 is scraped off by the cell walls and collected in the cells. Then, as the supply roller 52 rotates, the cells holding the toner move again toward the contact portion Dc.

[0109] Furthermore, when the cells holding toner reach the vicinity of the upstream end of the contact portion Dc in the rotation direction (R4) of the supply roller 52, the foam layer 522 elastically deforms again and the cells collapse. When the cells collapse and their volume decreases, the toner inside the cells is discharged and supplied to the developing roller 51.

[0110] Here, the toner present near the upstream end of the contact portion Dc in the rotation direction (R4) of the supply roller 52 is pushed by the toner discharged from the cells of the supply roller 52 and moves in the direction of arrow A1 through the gap between the outer peripheral surface 52s of the supply roller 52 and the wall surface of the developer-side accommodating portion 53a. The toner that has moved in the direction of arrow A1 mixes with other toner in the developer-side accommodating portion 53a (including toner that has just been replenished from the toner cartridge 70) in region C. Then, near the downstream end of the contact portion Dc in the rotation direction (R4) of the supply roller 52, the toner is again taken into the cells of the supply roller 52.

[0111] In this way, the toner contained in the developing side storage section 53a is supplied to the developing roller 51 by the supply roller 52 while circulating through area C, the cells of the supply roller 52, and the gap between the outer surface 52s of the supply roller 52 and the wall surface of the developing side storage section 53a.

[0112] (Reduction of fogging) The toner carried by the developing roller 51 is subjected to mechanical stress as it rubs against the developing blade 54, the photosensitive drum 2, and the supply roller 52, causing external additives on the surface of the toner particles to migrate to other components and causing the toner particles to deform. As the cumulative number of printed pages increases, the deterioration of the toner due to mechanical stress becomes more pronounced, making it difficult for the toner to be charged to the normal polarity even when rubbed against the developing blade 54. This type of toner is called "degraded toner." In contrast to degraded toner, the toner contained in the developing-side container 53a, which is easily charged to the normal polarity, is called "normal toner."

[0113] When the ratio of degraded toner to regular toner increases among the toner particles carried on the developing roller 51, the toner charge becomes insufficient. A toner charge insufficiency state occurs when a relatively large number of toner particles carried on the developing roller 51 and rubbing against the developing blade 54 have a charge close to zero or a charge opposite to the regular charge polarity. In this state of insufficient toner charge, toner adheres to areas on the surface of the photosensitive drum 2 where no electrostatic latent image is formed, and is transferred from the photosensitive drum 2 to the intermediate transfer belt and then to the recording material. As a result, a thin toner image adheres to areas of the recording material where no image is to be formed (non-image forming areas). This type of image defect is called "fog."

[0114] Fog is likely to occur when there is a large amount of degraded toner with poor charging performance on the developing roller 51. Therefore, fogging can be reduced by supplying regular toner to the developing roller 51 using the supply roller 52, scraping off the degraded toner on the developing roller 51, and promoting replacement of the toner on the developing roller 51.

[0115] However, as described above, the toner scraped off from the developing roller 51 circulates in the direction of arrow A1 within the developing-side accommodating portion 53a, mixes with other toner in area C, and is again taken into the cells of the supply roller 52 at the contact portion Dc. Therefore, in a configuration in which the toner cartridge 70 is not replaced (a configuration in which the developing unit 50 does not receive toner replenishment from the outside), the proportion of degraded toner in the developing-side accommodating portion 53a increases as the cumulative number of printed pages increases. As a result, the possibility of fogging occurring increases.

[0116] On the other hand, in a configuration in which the toner cartridge 70 is replaced (a configuration in which the developing unit 50 receives toner replenishment from the outside), toner is replenished to the developing-side accommodating portion 53a from the toner cartridge 70 attached to the rotary body 90. The toner replenished to the developing-side accommodating portion 53a from the toner cartridge 70 is called new toner (fresh toner). New toner is regular toner because its charging performance has not deteriorated. In a configuration in which the toner cartridge 70 is replaced, by supplying new toner to the developing-side accommodating portion 53a, the proportion of deteriorated toner in the developing-side accommodating portion 53a can be reduced.

[0117] Here, the likelihood of replacement of degraded toner with new toner on the developing roller 51 varies depending on which part of the developing-side accommodating section 53a the new toner is supplied to from the toner cartridge 70. The replacement of toner mainly occurs at the contact point Dc between the developing roller 51 and the supply roller 52.

[0118] Therefore, by configuring the toner supply path (arrow B in FIG. 7) so that at least a portion of the new toner is supplied to area C near contact portion Dc when rotary body 90 is in the development posture, it is possible to reduce fogging. Note that arrow B in FIG. 7 shows an example of the path along which toner is supplied from toner cartridge 70 to development-side accommodating portion 53a, and it is not necessary for all toner to move along arrow B.

[0119] In this embodiment, when the rotary body 90 is in the developing posture, the area C is located below the receiving opening 53b (in the -Z direction), and when viewed vertically, the area C at least partially overlaps with the receiving opening 53b. In other words, in FIG. 7, at least a portion of the line segment connecting the aforementioned contact points P51 and P52 is located between two imaginary lines 53b1 and 53b2 drawn vertically from both ends of the receiving opening 53b.

[0120] According to this configuration, after the toner cartridge 70 has been replaced, when the rotary body 90 is in the development posture, new toner supplied to the development-side accommodating portion 53a through the receiving opening 53b is more likely to fall into area C. Therefore, compared to when the receiving opening 53b is positioned so as not to overlap with area C when viewed vertically, for example, a higher proportion of new toner reaches area C out of the new toner supplied to the development-side accommodating portion 53a through the receiving opening 53b. Also, the proportion of new toner in area C increases.

[0121] As described above, the toner in region C is taken into the cells of the foam layer 522 near the downstream end of the contact portion Dc in the rotation direction (R4) of the supply roller 52. Also, the toner is expelled from the cells of the foam layer 522 near the upstream end of the contact portion Dc and supplied to the developing roller 51. Therefore, the higher the proportion of new toner in region C, the more new toner the supply roller 52 can take in and supply to the developing roller 51. As a result, the replacement of degraded toner with new toner on the developing roller 51 is promoted. By reducing the proportion of degraded toner on the developing roller 51, fogging is less likely to occur.

[0122] In this manner, in this embodiment, when the rotary body 90 is in the developing position, the area C is located below the receiving opening 53b, and is arranged so that the area C at least partially overlaps with the receiving opening 53b when viewed vertically. This facilitates the replacement of degraded toner on the developing roller 51 with new toner when the toner cartridge 70 is replaced, thereby preventing fogging.

[0123] That is, according to this embodiment, it is possible to provide an image forming apparatus capable of reducing fogging.

[0124] In this embodiment, two receiving openings 53b are arranged at both longitudinal ends of the developing frame 53, but it is sufficient that the area C at least partially overlaps with at least one of the receiving openings 53b when viewed vertically. If the area C at least partially overlaps with each of the two receiving openings 53b when viewed vertically, toner replacement can be promoted over a wider area on the developing roller 51, thereby further reducing fogging.

[0125] Example 2 In this embodiment, a configuration in which a guide member (check valve) is disposed in the developing-side accommodating portion 53a will be described. Hereinafter, elements with the same reference numerals as those in the first embodiment will have basically the same configuration and function as those described in the first embodiment unless otherwise specified, and differences from the first embodiment will be mainly described.

[0126] FIG. 8 is a cross-sectional view showing the photosensitive drum 2, the developing unit 50 (any one of the developing units 50y, 50m, 50c, and 50k), and the toner cartridge 70 corresponding to the developing unit 50 according to the second embodiment.

[0127] The developing unit 50 of this embodiment includes a guide member 55 disposed near the receiving opening 53b. The guide member 55 includes a seat portion 551 and a weight portion 552.

[0128] The sheet portion 551 is a resin sheet and extends in the X direction. In the short direction of the sheet portion 551 that intersects with the X direction, one end side (fixed end side) of the sheet portion 551 is a supported portion 554 that is supported by the developing frame 53. The supported portion 554 is fixed to the developing frame 53 by double-sided tape, welding, or the like. The sheet portion 551 is a sheet material (film) made of a resin material such as PET, generally Mylar (registered trademark) or Kapton (registered trademark), or a rubber material such as urethane rubber.

[0129] The weight portion 552 is attached to a tip 553, which is the other end (free end) of the seat portion 551. The weight portion 552 stabilizes the behavior of the seat portion 551. Furthermore, by providing the weight portion 552, the tip 553 of the guide member 55 can be positioned closer to the region C in the first posture of the rotary body 90 compared to when the weight portion 552 is not provided.

[0130] In this embodiment, for example, a 100 μm thick sheet material made of Mylar (registered trademark) resin is used as the sheet portion 551. The supported portion 554 of this sheet portion 551 is fixed to the developing frame 53 with double-sided tape at a position above (on the +Z side of) the receiving opening 53b when the rotary body 90 is in the developing posture.

[0131] The guide member 55 moves so that the seat portion 551 covers the receiving opening 53b when the rotary body 90 is in the replacement position, and so that the seat portion 551 retracts from the receiving opening 53b when the rotary body 90 is in the development position. In other words, the guide member 55 functions as a valve (check valve) that prevents toner from flowing out of the developer-side accommodating portion 53a through the receiving opening 53b when the rotary body 90 is in the replacement position. On the other hand, the guide member 55 allows toner to flow from the toner cartridge 70 into the developer-side accommodating portion 53a through the receiving opening 53b when the rotary body 90 is in the development position.

[0132] When viewed in the opening direction A53b of the receiving opening 53b with the rotary body 90 in the developing position, the tip 553 of the sheet portion 551 is located inside the receiving opening 53b. Therefore, when the toner flows from the toner cartridge 70 into the developer-side accommodating portion 53a through the receiving opening 53b, at least a portion of the toner comes into contact with the sheet portion 551 and is guided by the sheet portion 551 (arrow D). Note that arrow D in FIG. 8 shows an example of the path along which toner is supplied from the toner cartridge 70 to the developer-side accommodating portion 53a, and it is not necessary for all of the toner to move along arrow D.

[0133] In this embodiment as well, fogging can be reduced by configuring the new toner supply path (arrow D) to pass above area C near contact point Dc, and at least a portion of the new toner is supplied to area C. Area C is an area surrounded by the outer peripheral surface 51s of the developing roller 51, the outer peripheral surface 52s of the supply roller 52, and a common tangent line L1 to the outer peripheral surfaces 51s of the developing roller 51 and 52s of the supply roller 52, and is an area downstream of contact point Dc in the rotation direction (R4) of the supply roller 52.

[0134] Specifically, when the rotary body 90 is in the developing posture, the area C is located below the tip 553 of the guide member 55 and overlaps with the tip 553 of the guide member 55 when viewed in the vertical direction.

[0135] According to this configuration, after the toner cartridge 70 has been replaced, when the rotary body 90 is in the development posture, new toner supplied to the development-side accommodating section 53a through the receiving opening 53b is guided by the guide member 55 and more likely to fall into area C. Therefore, compared to when the tip 553 of the guide member 55 is positioned away from area C when viewed vertically, for example, a higher proportion of new toner reaches area C out of the new toner supplied to the development-side accommodating section 53a through the receiving opening 53b. Also, the proportion of new toner in area C increases. Therefore, similar to the first embodiment, it is possible to promote the replacement of degraded toner on the development roller 51 with new toner, thereby reducing fogging.

[0136] That is, according to this embodiment, it is possible to provide an image forming apparatus capable of reducing fogging.

[0137] Furthermore, in this embodiment, the inflow path of the new toner (arrow D) can be more accurately controlled by the guide member 55, allowing more new toner to fall into area C. Therefore, the toner on the developing roller 51 can be replaced with new toner in a shorter time than in the first embodiment, further suppressing fogging.

[0138] (Variation) 9, the guide member 55 may be configured to be supported by the developing frame 53 at a position below the receiving opening 53b. That is, when the rotary body 90 is in the development posture, the supported portion 554 of the seat portion 551 is fixed to the developing frame 53 with double-sided tape at a position below (on the +Z side of) the receiving opening 53b.

[0139] In this modified example, when the rotary body 90 is in the developing posture and viewed in the opening direction A53b of the receiving opening 53b, the tip 553 of the sheet portion 551 is located inside the receiving opening 53b. Therefore, when the toner flows from the toner cartridge 70 into the developer-side accommodating portion 53a through the receiving opening 53b, at least a portion of the toner comes into contact with the sheet portion 551 and is guided by the sheet portion 551 (arrow D). Furthermore, when the rotary body 90 is in the developing posture, the region C is located below the tip 553 of the guide member 55 and overlaps with the tip 553 of the guide member 55 when viewed vertically.

[0140] In this modified example, the new toner guided by the guide member 55 falls into the area C, which promotes the replacement of the deteriorated toner on the developing roller 51 with new toner, thereby reducing fogging.

[0141] (Other variations) In the above-described embodiments, the rotary body 90 includes four developing units 50y-50k and is capable of forming color images using four colors of toner. However, the rotary body 90 may include three or fewer developing units, or five or more developing units. In these cases, the number and arrangement of trays and toner cartridges can be appropriately changed according to the number of developing units. For example, in the above-described embodiments 1-4, a configuration in which four toner cartridges 70y-70k can be detachably attached to the rotary body 90 was illustrated. However, the rotary body 90 may include only one developing unit 50k, and only one toner cartridge 70k may be attached to the rotary body 90. In this case, the rotary body 90 rotates clockwise in FIG. 1 around the rotation axis 90C, and can alternate between a black replacement position and a black developing position.

[0142] In the above-described embodiments, the rotary body 90 is provided with four developing units 50y-50k, and a configuration capable of forming a color image using toner of four colors has been described. However, the rotary body 90 may have multiple developing units capable of forming images using toner of the same color. For example, the rotary body 90 may be configured to have four black developing units 50k, and four toner cartridges 70k may be attached to the rotary body 90.

[0143] Summary of the Disclosure The present disclosure includes at least the following: (Configuration 1) A photoreceptor; a rotatable rotary having a storage frame provided with a storage section for storing toner and a receiving opening communicating with the storage section, a rotatable developing roller for carrying toner and supplying it to the photosensitive member, and a rotatable supply roller for supplying the toner stored in the storage section to the developing roller; a toner cartridge that contains toner therein and is detachable from the rotary, the toner cartridge having a discharge opening that communicates with the receiving opening, and configured so that toner discharged from the discharge opening is supplied to the storage section through the receiving opening; Equipped with the supply roller has a foam layer formed of a foam material and forming an outer peripheral surface of the supply roller, and is arranged so that the foam layer is elastically deformed at a contact portion between the supply roller and the developing roller; the rotary can be in an exchange position in which the toner cartridge can be attached to and detached from the rotary, and a development position in which the developing roller can supply toner to the photosensitive member; When a downstream region is defined as a region surrounded by the outer circumferential surface of the developing roller, the outer circumferential surface of the supply roller, and a common tangent to the outer circumferential surfaces of the developing roller and the supply roller, and which is downstream of the contact portion in the rotation direction of the supply roller, when the rotary is in the developing posture, the downstream region is located below the receiving opening and at least partially overlaps with the receiving opening when viewed in the vertical direction. An image forming apparatus characterized by: (Configuration 2) A photoreceptor; a rotatable rotary having a storage frame provided with a storage section for storing toner and a receiving opening communicating with the storage section, a rotatable developing roller for carrying toner and supplying it to the photosensitive member, a rotatable supply roller for supplying the toner stored in the storage section to the developing roller, and a guide member disposed in the storage section and for guiding the toner supplied to the storage section through the receiving opening; a toner cartridge that contains toner therein and is detachable from the rotary, the toner cartridge having a discharge opening that communicates with the receiving opening, and configured so that toner discharged from the discharge opening is supplied to the storage section through the receiving opening; Equipped with the supply roller has a foam layer formed of a foam material and forming an outer peripheral surface of the supply roller, and is arranged so that the foam layer is elastically deformed at a contact portion between the supply roller and the developing roller; the rotary can be in an exchange position in which the toner cartridge can be attached to and detached from the rotary, and a development position in which the developing roller can supply toner to the photosensitive member; the guide member has a supported portion that is supported by the accommodating frame body, and a tip that is located inside the receiving opening when viewed in the direction of the receiving opening when the rotary is in the developing posture, when a downstream region is defined as a region surrounded by the outer circumferential surface of the developing roller, the outer circumferential surface of the supply roller, and a common tangent to the outer circumferential surfaces of the developing roller and the supply roller, and which is downstream of the contact portion in the rotation direction of the supply roller, when the rotary is in the developing posture, the downstream region is located below the tip of the guide member and overlaps with the tip of the guide member when viewed in the vertical direction; An image forming apparatus characterized by: (Configuration 3) The guide member is a sheet material made of a resin material or a rubber material. 3. The image forming apparatus according to configuration 2. (Configuration 4) the guide member is configured to prevent toner from flowing out of the container through the receiving opening when the rotary is in the replacement position. 4. The image forming apparatus according to configuration 2 or 3. (Configuration 5) When the rotary is in the replacement position, the opening direction of the receiving opening faces downward in the vertical direction; When the rotary is in the developing posture, the opening direction of the receiving opening faces upward in the vertical direction. 5. The image forming apparatus according to any one of configurations 1 to 4. (Configuration 6) The toner cartridge is configured such that, when the opening direction of the discharge opening faces downward in the vertical direction, toner is discharged from inside the toner cartridge through the discharge opening by gravity. 6. The image forming apparatus according to any one of configurations 1 to 5. (Configuration 7) The receiving opening is a first receiving opening, the accommodating frame has a second receiving opening that communicates with the accommodating portion and receives toner from the toner cartridge; the first receiving opening is disposed on one side of the center of the accommodating portion in the direction of the rotation axis of the rotary; the second receiving opening is disposed on the other side of the center of the accommodating portion in the rotational axis direction, When the rotary is in the developing attitude, the downstream area at least partially overlaps with each of the first receiving opening and the second receiving opening when viewed in the vertical direction. 7. The image forming apparatus according to any one of configurations 1 to 6. (Configuration 8) the supply roller is disposed so that its intrusion into the developing roller is 0.1 mm or more and 1.5 mm or less; a moving direction of the outer peripheral surface of the developing roller at the contact portion and a moving direction of the outer peripheral surface of the supply roller at the contact portion are opposite to each other; 8. The image forming apparatus according to any one of configurations 1 to 7. (Configuration 9) The foam layer is a polyurethane foam having an open cell structure and an average cell diameter of 10 μm or more and 800 μm or less. 9. The image forming apparatus according to any one of configurations 1 to 8. [Explanation of symbols]

[0144] 2...photosensitive member (photosensitive drum) / 51...developing roller / 52...supply roller / 522...foam layer / 53...accommodating frame (developing frame) / 53a...accommodating section (developing side accommodating section) / 53b...receiving opening / 55...guide member / 70...toner cartridge / 90...rotary (rotary main body) / C...area / Dc...contact section

Claims

1. A photoreceptor; a rotatable rotary having a storage frame provided with a storage section for storing toner and a receiving opening communicating with the storage section, a rotatable developing roller for carrying toner and supplying it to the photosensitive member, and a rotatable supply roller for supplying the toner stored in the storage section to the developing roller; a toner cartridge that contains toner therein and is detachable from the rotary, the toner cartridge having a discharge opening that communicates with the receiving opening, and configured so that toner discharged from the discharge opening is supplied to the storage section through the receiving opening; Equipped with the supply roller has a foam layer formed of a foam material and forming an outer peripheral surface of the supply roller, and is arranged so that the foam layer is elastically deformed at a contact portion between the supply roller and the developing roller; the rotary can be in an exchange position in which the toner cartridge can be attached to and detached from the rotary, and a development position in which the developing roller can supply toner to the photosensitive member; When a downstream region is defined as a region surrounded by the outer circumferential surface of the developing roller, the outer circumferential surface of the supply roller, and a common tangent to the outer circumferential surfaces of the developing roller and the supply roller, and which is downstream of the contact portion in the rotation direction of the supply roller, when the rotary is in the developing posture, the downstream region is located below the receiving opening and at least partially overlaps with the receiving opening when viewed in the vertical direction. An image forming apparatus characterized by:

2. A photoreceptor; a rotatable rotary having a storage frame provided with a storage section for storing toner and a receiving opening communicating with the storage section, a rotatable developing roller for carrying toner and supplying it to the photosensitive member, a rotatable supply roller for supplying the toner stored in the storage section to the developing roller, and a guide member disposed in the storage section and for guiding the toner supplied to the storage section through the receiving opening; a toner cartridge that contains toner therein and is detachable from the rotary, the toner cartridge having a discharge opening that communicates with the receiving opening, and configured so that toner discharged from the discharge opening is supplied to the storage section through the receiving opening; Equipped with the supply roller has a foam layer formed of a foam material and forming an outer peripheral surface of the supply roller, and is arranged so that the foam layer is elastically deformed at a contact portion between the supply roller and the developing roller; the rotary can be in an exchange position in which the toner cartridge can be attached to and detached from the rotary, and a development position in which the developing roller can supply toner to the photosensitive member; the guide member has a supported portion that is supported by the accommodating frame body, and a tip that is located inside the receiving opening when viewed in the direction of the receiving opening when the rotary is in the developing posture, when a downstream region is defined as a region surrounded by the outer circumferential surface of the developing roller, the outer circumferential surface of the supply roller, and a common tangent to the outer circumferential surfaces of the developing roller and the supply roller, and which is downstream of the contact portion in the rotation direction of the supply roller, when the rotary is in the developing posture, the downstream region is located below the tip of the guide member and overlaps with the tip of the guide member when viewed in the vertical direction; An image forming apparatus characterized by:

3. The guide member is a sheet material made of a resin material or a rubber material.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. the guide member is configured to prevent toner from flowing out of the container through the receiving opening when the rotary is in the replacement position.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

5. When the rotary is in the replacement position, the opening direction of the receiving opening faces downward in the vertical direction; When the rotary is in the developing posture, the opening direction of the receiving opening faces upward in the vertical direction.

5. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

6. The toner cartridge is configured such that, when the opening direction of the discharge opening faces downward in the vertical direction, toner is discharged from inside the toner cartridge through the discharge opening by gravity.

5. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

7. The receiving opening is a first receiving opening, the accommodating frame has a second receiving opening communicating with the accommodating portion and receiving the toner from the toner cartridge; the first receiving opening is disposed on one side of the center of the accommodating portion in the direction of the rotation axis of the rotary; the second receiving opening is disposed on the other side of the center of the accommodating portion in the rotational axis direction, When the rotary is in the developing attitude, the downstream area at least partially overlaps with each of the first receiving opening and the second receiving opening when viewed in the vertical direction.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

8. the supply roller is disposed so that its intrusion into the developing roller is 0.1 mm or more and 1.5 mm or less; a moving direction of the outer peripheral surface of the developing roller at the contact portion and a moving direction of the outer peripheral surface of the supply roller at the contact portion are opposite to each other; 5. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. The foam layer is a polyurethane foam having an open cell structure and an average cell diameter of 10 μm or more and 800 μm or less.

5. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

Images