Image forming apparatus

Abstract

The objective is to further develop the conventional configuration in an image forming apparatus in which a passage for toner extends from the toner container to the storage area of ​​the main body of the apparatus. [Solution] An image forming apparatus comprising a toner container provided with an outlet, and an apparatus body including a main frame to which the toner container can be attached and detached and which is provided with a communication port that communicates with the outlet, wherein the apparatus body comprises a drum unit having a photosensitive drum, a developing frame including a receiving port and a storage section for storing toner, and a developing roller, and a developing unit that is movable between a developing contact position and a developing separation position, and a flexible tube extending from a first end connected to the main frame so as to communicate with the communication port to a second end connected to the developing unit so as to communicate with the receiving port, and bending between the first end and the second end as the developing unit moves between the contact position and the separation position.

Description

Technical Field

[0001] The present invention relates to an electrophotographic image forming apparatus.

Background Art

[0002] In an electrophotographic image forming apparatus, a configuration is disclosed in which toner is conveyed from a container having a detachable replenishment port for a toner container to a developing device using a toner tube extending from the container to the developing device (Patent Document 1). A configuration is disclosed in which a seal member provided between the toner tube and the developing device elastically deform according to the movement of the developing device to suppress toner leakage when the developing device moves relative to the photosensitive drum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] It is an object to further develop the configuration of a conventional image forming apparatus.

Means for Solving the Problems

[0005] One aspect of the present invention is an image forming apparatus comprising: a toner container for containing toner and having an outlet for discharging toner; a main body frame to which the toner container can be attached and detached, the main body frame including a communication opening that communicates with the outlet, wherein the main body comprises: a drum unit having a photosensitive drum; a developing frame having a receiving port for receiving toner and including a storage section for containing toner; and a developing roller carrying the toner contained in the storage section and supplying toner to the photosensitive drum, wherein the developing roller contacts the photosensitive drum with respect to the drum unit and the developing roller is separated from the photosensitive drum The device comprises a developing unit configured to be movable between a separation position and the photosensitive drum and the main body frame, and a passage through which toner discharged from the discharge port of the toner container passes when transported from the communication port to the receiving port, having a first end connected to the main body frame so as to communicate with the communication port, and a second end connected to the developing unit so as to communicate with the receiving port, and extending from the first end to the second end, wherein the passage is made of a flexible tube and is configured to bend between the first end and the second end as the developing unit moves between the contact position and the separation position. [Effects of the Invention]

[0006] According to the present invention, the configuration of conventional image forming apparatuses can be further developed. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of the image forming apparatus according to Example 1. [Figure 2] This is a perspective view of an image forming apparatus for illustrating the attachment and detachment of a cartridge according to Example 1. [Figure 3] This is a perspective view of the image forming unit according to Example 1. [Figure 4]These are top views of the image forming unit and scanner unit according to Example 1, and a top view of the image forming unit. [Figure 5] This is a cross-sectional view AA shown in Figure 4. [Figure 6] Figure 4 is a cross-sectional view of the BB, showing the contact and separation positions of the developing unit. [Figure 7] These are the front view, top view, side view, rear view, and bottom view of the cartridge according to Example 1. [Figure 8] These are cross-sectional views, perspective views, and exploded perspective views of the cartridge according to Example 1. [Figure 9] These are cross-sectional views and perspective views of the cartridge according to Example 1. [Figure 10] This is a perspective view showing the contact and separation states of an image forming unit equipped with a low-friction member according to Example 1. [Figure 11] These are a cross-sectional view of the image forming unit and a perspective view and a front view of the low-friction member according to Example 1. [Figure 12] This is a perspective view showing the contact and separation states of an image forming unit equipped with a low-friction member according to Example 2. [Figure 13] These are a cross-sectional view of the image forming unit and a perspective view and a front view of the low-friction member according to Example 2. [Figure 14] This is a perspective view showing the contact and separation states of an image forming unit equipped with a low-friction member according to Example 3. [Modes for carrying out the invention]

[0008] [Example 1] [Image forming apparatus] An image forming apparatus 1 according to Embodiment 1 of the present invention will be described with reference to Figure 1. The electrophotographic image forming apparatus of this embodiment is a full-color image forming apparatus equipped with four color process cartridges. Figure 1 is a main cross-section of the image forming apparatus 1.

[0009] The image forming apparatus 1 is a full-color laser printer using an electrophotographic process, and is capable of forming full-color images on a recording medium S. The image forming apparatus 1 comprises a process unit PY (second process unit), a process unit PM (first process unit), a process unit PC, a process unit PK (hereinafter referred to as each process unit P), and a main body 72 of the apparatus. Here, each process unit P is arranged to be aligned in a first direction X, and the toner colors contained inside are different from each other. The longitudinal direction of each process unit P is a second direction Y perpendicular to the first direction.

[0010] Each process unit P has an electrophotographic process element. Rotational driving force is transmitted to each process unit P from the drive output section (not shown) of the main body 72 of the apparatus, and a bias voltage (charging bias, development bias, etc.) is supplied from the bias application section (not shown) of the main body 72 of the apparatus.

[0011] As shown in Figure 1, each process unit P comprises a drum unit 8Y (first drum unit), a drum unit 8M (second drum unit), a drum unit 8C, and a drum unit 8K (hereinafter referred to as each drum unit 8). Each drum unit 8 has a photosensitive drum 4Y (second photosensitive drum), a photosensitive drum 4M (first photosensitive drum), a photosensitive drum 4C, and a photosensitive drum 4K (hereinafter referred to as each photosensitive drum 4). Each drum unit 8 also has charging rollers 5Y, 5M, 5C, and 5K (hereinafter referred to as each charging roller 5) as process means that act on each photosensitive drum 4. Each photosensitive drum 4 is arranged so that the direction of its rotation axis is in the second direction Y.

[0012] Each process unit P includes a developing unit 9Y (second developing unit), 9M (first developing unit), 9C, and 9K (hereinafter, each developing unit 9). Each developing unit 9 has a developing roller 6Y (second developing roller), a developing roller 6M (first developing roller), a developing roller 6C, and a developing roller 6K (hereinafter, each developing roller 6) that develop the electrostatic latent image on the corresponding photosensitive drum 4. Each developing unit 9 is aligned in the first direction X.

[0013] Each developing unit 9 includes a developing container 3Y (second storage unit, second developing frame), 3M (first storage unit, first developing frame), 3C, and 3K (hereinafter, each developing container 3). The developing unit 9Y has a developing container 3Y (second developing container) that stores yellow (Y) toner (second toner), and is configured such that the yellow (Y) toner is supplied to the surface of the photosensitive drum 4Y by the developing roller 6Y that carries the yellow (Y) toner. The developing unit 9M has a developing container 3M (first developing container) that stores magenta (M) toner (first toner), and is configured such that the magenta (M) toner is supplied to the surface of the photosensitive drum 4M by the developing roller 6M that carries the magenta (M) toner. The developing unit 9C has a developing container 3C that stores cyan (C) toner (third toner), and is configured such that the cyan (C) toner is supplied to the surface of the photosensitive drum 4C by the developing roller 6C that carries the cyan (C) toner. The developing unit 9K has a developing container 3K that stores black (K) toner (fourth toner), and is configured such that the black (K) toner is supplied to the surface of the photosensitive drum 4K by the developing roller 6K that carries the black (K) toner.

[0014] In a third direction Z that intersects both the first direction X and the second direction Y, above each process unit P (each photosensitive drum 4), a laser scanner unit LB (exposure unit) is provided. This laser scanner unit LB outputs laser light corresponding to image information. Hereinafter, the optical paths of the laser light directed to the photosensitive drums 4Y, 4M, 4C, and 4K are respectively LY, LM, LC, and LK (hereinafter, each optical path L or the optical path L is also denoted as such). And the laser light scans and exposes the surface of each photosensitive drum 4. Note that an LED exposure unit may be used instead of the laser scanner unit LB.

[0015] Below the process unit P in the third direction Z, an intermediate transfer belt unit 11 as a transfer member is provided. This intermediate transfer belt unit 11 has a driving roller 14, a tension roller 13, and an assist roller 15, and a flexible transfer belt 12 is wound around them.

[0016] The lower surface of each photosensitive drum 4 is in contact with the upper surface of the transfer belt 12. The contact portions between each photosensitive drum 4 and the transfer belt 12 are primary transfer portions 30Y, 30M, 30C, and 30K (hereinafter, denoted as the primary transfer portion 30). Inside the transfer belt 12, primary transfer rollers 16Y, 16M, 16C, and 16K (hereinafter, denoted as the transfer roller 16) are provided facing each photosensitive drum 4.

[0017] A secondary transfer roller 17 is pressed against the driving roller 14 via the transfer belt 12. The contact portion between the transfer belt 12 and the secondary transfer roller 17 is the secondary transfer portion 31.

[0018] Below the intermediate transfer belt unit 11 in the third direction Z, a feeding unit 18 is provided. The feeding unit 18 has a paper feed tray 19 for loading and accommodating the recording medium S, and a paper feed roller 20 for picking up and conveying the recording medium S from the paper feed tray 19.

[0019] In Figure 1, the upper part of the main body 72 of the device is provided with a fixing unit 21 for fixing the toner image onto the recording medium S, and an ejection roller 22 for ejecting the recording medium S with the toner image fixed onto it to the ejection tray 23. The ejection roller 22 ejects the recording medium S in a direction along the first direction X. In this embodiment, the downstream side in the ejection direction from which the recording material S is ejected toward the ejection tray 23 by the ejection roller 22 is considered the front side of the image forming apparatus 1, and the upstream side in the ejection direction is considered the rear side of the image forming apparatus 1.

[0020] [Image Formation Process] The operation for forming a full-color image is as follows: Each photosensitive drum 4 is driven to rotate counterclockwise at a predetermined speed in Figure 1. The transfer belt 12 is driven to rotate in the forward direction of the rotation of each photosensitive drum 4 at a speed corresponding to the rotational speed of each photosensitive drum 4.

[0021] The laser scanner unit LB is also driven. Synchronized with the driving of the laser scanner unit LB, the charging roller 5 in each process unit P uniformly charges the surface of each corresponding photosensitive drum 4 to a predetermined polarity and potential. The laser scanner unit LB scans and exposes the surface of each charged photosensitive drum 4 with laser light L according to the image signal of each color, and an electrostatic latent image corresponding to the image signal of each color is formed on the surface of each photosensitive drum 4. In other words, the laser scanner unit LB exposes the photosensitive drum 4Y and the photosensitive drum 4M, and forms a first electrostatic latent image and a second electrostatic latent image on the photosensitive drum 4Y and the photosensitive drum 4M, respectively. Similarly, the laser scanner unit LB exposes the photosensitive drum 4C and the photosensitive drum 4K, and forms a third electrostatic latent image and a fourth electrostatic latent image on the photosensitive drum 4C and the photosensitive drum 4K, respectively.

[0022] The electrostatic latent image on each photosensitive drum 4 is developed by the supply of toner to each photosensitive drum 4 by each developing roller 6, which is driven to rotate clockwise at a predetermined speed as shown in Figure 1. Through the electrophotographic image formation process described above, a yellow toner image is formed on the photosensitive drum 4Y of process unit PY. This yellow toner image is then primary transferred onto the transfer belt 12. Similarly, a magenta toner image is formed on the photosensitive drum 4M of process unit PM. This magenta toner image is then primary transferred onto the transfer belt 12 so as to be superimposed on the yellow toner image on the transfer belt 12. A cyan toner image is formed on the photosensitive drum 4C of process unit PC. This cyan toner image is then primary transferred onto the transfer belt 12 so as to be superimposed on the yellow and magenta toner images on the transfer belt 12. A black toner image is formed on the photosensitive drum 4K of process unit PK. Then, the black toner image is primary transferred onto the transfer belt 12 so as to be superimposed on the yellow, magenta, and cyan toner images on the transfer belt 12.

[0023] In this way, a full-color unfixed toner image of four colors—yellow, magenta, cyan, and black—is formed on the transfer belt 12. Meanwhile, at a predetermined control timing, the recording media S are separated one by one from the paper tray 19 by the paper feed roller 20 and fed. The recording media S is introduced at a predetermined control timing into the secondary transfer section 31, which is the contact point between the secondary transfer roller 17 and the transfer belt 12. As the recording media S is transported in the secondary transfer section 31, the four-color superimposed toner image on the transfer belt 12 is transferred to the recording media S. The recording media S on which the toner image has been transferred is heated and pressurized by the fixing unit 21, and the toner image is fixed to the recording media S. The recording media S on which the toner image has been fixed is discharged into the discharge tray 23 by the discharge roller 22.

[0024] [Cartridge placement and removal] The image forming apparatus 1 has cartridges 430Y (second cartridge, second toner container), cartridge 430M (first cartridge, first toner container), cartridge 430C, and cartridge 430K (hereinafter, each cartridge 430) as detachable supply containers attached to the apparatus body 72. Each cartridge 430 is aligned in the second direction Y. In other words, each cartridge 430 is aligned in a direction that intersects (is perpendicular to) the direction in which each developing unit 9 is aligned.

[0025] Figure 2(a) is a perspective view of the image forming apparatus 1 with the front door 72b closed. Figure 2(b) is a perspective view of the image forming apparatus 1 with the front door 72b open. Figure 2(c) is a perspective view of the image forming apparatus 1 with the front door 72b open and the cartridge 430Y removed from the cartridge holder 511. The cartridge holder 511 is a mounting section (part of the main frame) from which each cartridge 430 can be attached and detached.

[0026] Each cartridge 430 is mounted on the upper front side of the apparatus body 72 so that it can be accessed by opening the front door 72b. In other words, each cartridge 430 is located at the downstream end of the apparatus body 72 in the discharge direction of the discharge roller 22. The front door 72b is configured to move between a closed position (see Figure 2(a)) that closes the opening of the apparatus body 72 on the front side and an open position (see Figure 2(b)) that opens the opening. When the front door 72b is moved to the open position, each cartridge 430 is exposed to the outside of the image forming apparatus 1 through the opening, as shown in Figure 2(b). Each cartridge 430 is arranged in a second direction Y and is configured to be detachable from the apparatus body 72 in a first direction X, as shown in Figure 2(c). This allows each process unit P to be detached from the apparatus body 72. Toner can be replenished to each process unit P. Since each cartridge 430 is positioned on the front side of the image forming apparatus 1, each cartridge 430 can be accessed from the front side, similar to the retrieval of the recording medium S discharged into the discharge tray 23. In addition, since the cartridge holder 511 is located on the front side of the image forming apparatus 1, the process unit P is not exposed even after each cartridge 430 is removed (see Figure 2(c)). Each cartridge 430 is stored inside the apparatus body 72 when the front door 72b is closed.

[0027] As shown in Figure 2(a), indicators 208Y, 208M, 208C, and 208K (hereinafter referred to as each indicator 208) (indication section, display section) of each color are provided on the front of the image forming apparatus 1. Each indicator 208 is arranged in the second direction Y to correspond to each cartridge 430. Indicator 208Y is yellow, indicator 208M is magenta, indicator 208C is cyan, and indicator 208K is black. Each indicator 208 consists of an LED or sticker of the color corresponding to the toner color of each cartridge and is provided to prevent incorrect installation of each cartridge 430. In addition, each indicator 208 may also have a toner level display function for the corresponding process unit P (each developing unit 9).

[0028] As shown in Figure 2(b), the lower side of the cartridge holder 511 has an inclined portion 511a. The inclined portion 511a is a sloped surface that is angled upwards from the main body, and labels 210 corresponding to the toner color of each cartridge are attached to it. When a user replaces a cartridge, they can see the labels 210 on the inclined portion 511a, so they can install each cartridge 430 in the designated position.

[0029] [Image Forming Unit] The toner transport mechanism from each cartridge 430 to the corresponding process unit P will be explained using Figures 3 to 5.

[0030] The image forming unit 50 includes each cartridge 430, each process unit P, and a transport path for transporting toner from each cartridge 430 to each process unit P, which will be described later. Figure 3(a) is a perspective view of the image forming unit 50 with each cartridge 430 installed. Figure 3(b) is a perspective view of the image forming unit with each cartridge 430 removed. Figure 4(a) is a top view of the laser scanner unit LB and the image forming unit 50. Figure 4(b) is a top view of the image forming unit 500 only.

[0031] Figure 5(a) is a cross-section of AA in Figure 4(a). Figure 6(a) is a cross-sectional view of BB with the image forming unit 50 in contact with the surface in Figure 4(a). Figure 6(b) is a cross-sectional view of BB with the image forming unit 50 separated from the surface in Figure 4(a).

[0032] As shown in Figure 3(a), the image forming unit 500 is arranged such that the process cartridges P (PY, PM, PC, PK) are aligned in a first direction X. The process cartridges P are mounted on a tray 55. The front of the tray 55 is a cartridge holder 511, on which a cartridge 430 is mounted. The cartridge 430 is arranged so as to be aligned in a second direction Y.

[0033] A pump unit 80 is provided above the process cartridge PK. The pump unit 80 is supported by a support member 56 and attached to the cartridge holder 511.

[0034] The pump unit 80 consists of four pumps to supply air to each cartridge 430. Each pump is a positive displacement pump, such as a reciprocating pump or a rotary pump. Reciprocating pumps perform suction and discharge by the reciprocating motion of a piston or plunger, and include piston pumps, plunger pumps, and diaphragm pumps. Rotary pumps perform suction and discharge by the rotational motion of gears or rotors, and include gear pumps, screw pumps, and vane pumps. In this embodiment, each pump unit 80 is provided in the image forming unit 50, but it may also be provided in each cartridge 430 or the main body of the device 72.

[0035] [Air supply from the air supply port to the cartridge] As shown in Figures 3(b) and 5, the portion of the cartridge holder 511 facing the lower surface of each cartridge 430 is provided with an opening that exposes the air supply ports 514a, 514b, 514c, and 514d (hereinafter referred to as each air supply port 514) supplied by each pump unit 80. The air supply ports 514 open upwards.

[0036] The air discharged upward from each air supply port 514 is supplied to the inside of each cartridge 430 mounted in the cartridge holder 511. The air supplied to the inside of each cartridge 430 is then discharged to the outside along with the toner. The internal structure of each cartridge 430 will be described later.

[0037] The toner discharged from each cartridge 430 along with air is received by tubes 62Y, 62M, 62C, and 62K (hereinafter referred to as tubes 62) (toner transport tubes) via receiving ports 51aY (second communication port), 51aM (first communication port), 51aC, and 51aK (hereinafter referred to as receiving ports 51a) provided in the cartridge holder 511 shown in Figure 3(b). Each tube 62 extends to and is connected to each developing unit 9. Each receiving port 51a is a through-hole provided so as to penetrate the surface of the cartridge holder 511 facing the back of each cartridge 430. Each receiving port 51a opens toward a first direction X, which is the direction in which the developing units 9 are lined up. The direction in which each receiving port 51a opens intersects with the direction in which each air supply port 514 opens.

[0038] The toner received from each inlet 51a is moved through the inside of each tube 62 by air discharged from each cartridge 430 from each upstream end 62u to each downstream end 62d (62Yd, 62Md, 62Cd, 62Kd) (hereinafter referred to as each downstream end 62) (hereinafter referred to as each downstream end 62) and supplied to each developing unit 9.

[0039] Each developing container 3, which is the toner storage area for each developing unit 9, is provided with a toner receiving port 33 (33Y, 33M, 33C, 33K) on its upper surface. Toner T is supplied to each developing container 3 along with air through each toner receiving port.

[0040] The image forming unit 50 is preferably configured to allow easy access to the process unit P and tube 62 for maintenance and replacement of these components in the event of a malfunction or other service issue. Therefore, in this embodiment, the image forming unit 500 is configured to be able to be pulled out from the BE side (rear side) to the FE side (front side) relative to the main body 72 (intermediate transfer belt unit 11).

[0041] [Cartridge structure] The structure of each cartridge 430 (toner container) in this embodiment will be explained using Figures 7 to 9. Since the basic structure of each cartridge 430 is the same, we will explain cartridge 430Y. Figures 7(a), (b), (c), (d), and (e) are the front view, top view, bottom view, right side view, and rear view of cartridge 430Y, respectively.

[0042] Figure 8(a) is a cross-sectional view of HH in Figure 7(e). Figure 8(b) is a perspective view of cartridge 430Y. Figure 8(c) is an exploded perspective view of cartridge 430Y. Figure 9(a) is a cross-sectional view of GG in Figure 7(b). Figure 9(b) is a perspective view of Figure 9(a). Note that the following description of the structure of cartridge 430Y is based on the state (position) in which cartridge 430Y is attached to cartridge holder 511.

[0043] As shown in Figure 8, cartridge 430Y includes a first frame 430Ya, a second frame 430Yb, a filter 83Y (first filter, first ventilation member), and a discharge pipe 85Y (first discharge pipe, first passage). Although not shown, cartridge 430M similarly includes a third frame 430Ma, a fourth frame 430Mb, a filter 83M (second filter, second ventilation member), and a discharge pipe 85M (second discharge pipe, second passage). Similarly, cartridge 430C also includes a fifth frame 430Ca, a sixth frame 430Cb, a filter 83C (third filter, third ventilation member), and a discharge pipe 85C (third discharge pipe, third passage). Similarly, cartridge 430K also includes a seventh frame 430Ka, an eighth frame 430Kb, a filter 83K (fourth filter, fourth ventilation member), and a discharge pipe 85K (fourth discharge pipe, fourth passage).

[0044] Although the first frame 430Ya and the second frame 430Yb in this embodiment are made of resin, they may also be made of paper or the like. As shown in Figure 7(e), an outlet 430Ya1 (first outlet) is provided on the back surface 4300Ya of the first frame 430Ya. As shown in Figure 7(c), a receiving port 430Yb1 (first receiving port, first intake port) is provided on the bottom surface 4300Yb of the second frame 430Yb. It is preferable to provide the outlet 430Ya1 and the receiving port 430Yb1 on the surface of the cartridge 430Y, excluding the surface that intersects the second direction Y, which is the direction in which each cartridge 430 is aligned (the surface facing the second direction Y). This makes it possible to reduce the gap G (Gym, Gmc, Gck) between each cartridge 430 shown in Figure 3(a). As a result, the width L of each cartridge 430 can be increased, and the volume for storing toner can be increased. Gap Gym is the gap in the second direction Y between cartridge 430Y and cartridge 430M. Gap Gmc is the gap in the second direction Y between cartridge 430M and cartridge 430C. Gap Gck is the gap in the second direction Y between cartridge 430C and cartridge 430K.

[0045] Furthermore, the discharge port 430Ya1 is provided on the back surface 4300Ya of the cartridge 430Y (the downstream end surface in the mounting direction of the cartridge 430Y) so as to open toward the downstream side in the mounting direction. Therefore, when mounting the cartridge 430Y into the cartridge holder 511, it is easier to engage the discharge port 430Ya1 with the receiving port 429Ya of the cartridge holder 511 so as to communicate with it. Alternatively, the discharge port 430Ya1 may be provided on the bottom surface 4300Yb or top surface of the cartridge 430Y, and the receiving port 430Yb1 may be provided on the back surface 4300Ya or top surface. If there is sufficient space in the main body of the device 72, the discharge port 430Ya1 and the receiving port 430Yb1 may be provided on surfaces intersecting the second direction Y. Although not shown in the diagram, cartridge 430M has an outlet 430Ma1 (second outlet) and an inlet 430Mb1 (second inlet, second intake) arranged in the same configuration as cartridge 430Y. Cartridge 430C has an outlet 430Ca1 (third outlet) and an inlet 430Cb1 (third inlet, third intake) arranged in the same configuration as cartridge 430Y. Cartridge 430K has an outlet 430Ka1 (fourth outlet) and an inlet 430Kb1 (fourth inlet, fourth intake) arranged in the same configuration as cartridge 430Y.

[0046] An unillustrated sealing member (seal or shutter) may be provided at the discharge port 430Ya1. When the cartridge 430Y is not mounted in the cartridge holder 511 of the device body 72, the sealing member seals the discharge port 430Ya1 to prevent the toner T contained inside from leaking out of the cartridge 430Y. When the cartridge 430Y is mounted in the cartridge holder 511, the sealing member is removed or moved so that the discharge port 430Ya1 is open.

[0047] The label 430Ys on the front of the cartridge 430Y shown in Figure 7(a) is for indicating the color of the toner inside. The label 430Ys may also contain instructions illustrating how to install the cartridge 430Y into the cartridge holder 511, or it may display any information about the cartridge 430Y.

[0048] The first frame 430Ya and the second frame 430Yb each have flange portions 430Ya2 and 430Yb2, respectively. The internal space SPY of the cartridge 430Y shown in Figure 8(a) is formed by welding the flange portions 430Ya2 and 430Yb2 to each other by ultrasonic welding. The flange portions 430Ya2 and 430Yb2 may also be fixed to each other with adhesive or screws.

[0049] Filter 83Y is installed to divide the internal space SPY of cartridge 430Y into two parts: the toner chamber 430Yc (first chamber) and the air chamber 430Yd (second chamber). In other words, the air chamber 430Yd is adjacent to the toner chamber 430Yc via filter 83Y. Although not shown in the diagram, filter 83M is installed to divide the internal space SPM of cartridge 430M into two parts: the toner chamber 430Mc (third chamber) and the air chamber 430Md (fourth chamber). In other words, the air chamber 430Md is adjacent to the toner chamber 430Mc via filter 83M. Filter 83C is installed to divide the internal space SPC of cartridge 430C into two parts: the toner chamber 430Cc (fifth chamber) and the air chamber 430Cd (sixth chamber). In other words, the air chamber 430Cd is adjacent to the toner chamber 430Cc via filter 83C. Filter 83K is installed to divide the internal space SPK of cartridge 430K into two parts: the toner chamber 430Kc (seventh chamber) and the air chamber 430Kd (eighth chamber). In other words, the air chamber 430Kd is adjacent to the toner chamber 430Kc via filter 83K.

[0050] The toner chamber 430Yc is located above the air chamber 430Yd and is aligned with the air chamber 430Yd in a third direction Z. In other words, the orientation in which the cartridge 430Y is oriented so that the toner chamber 430Yc is above the air chamber 430Yd is the mounting orientation for the device body 72. The alignment direction of the toner chamber 430Yc and the air chamber 430Yd is the third direction Z. Therefore, in this embodiment, the receiving port 430Yb1 opens toward this alignment direction, and the discharge port 430Ya1 opens in a direction intersecting this alignment direction.

[0051] The toner chamber 430Yc is configured to house the toner T. In the toner chamber 430Yc, the toner T is supported by the filter 83Y.

[0052] The air chamber 430Yd does not contain toner. The filter 83Y is made of a porous material, for example, made of resin fibers, and has a pore size and density that allows air to pass through but inhibits toner from passing through. In other words, the filter 83Y is configured to allow air to pass through but inhibit toner from passing through. As shown in Figures 7 and 8, the filter 83Y is held by the first frame 430Ya and the second frame 430Yb, with its outer edge 83Ya sandwiched between the flange portion 430Ya2 of the first frame 430Ya and the flange portion 430Yb2 of the second frame Yb. The filter 83Y is inclined from the outer edge 83Ya towards the lowest part 83Yb, which is below the outer edge 83Ya. In other words, the filter 83Y has a portion (inclined portion) that slopes downward as it approaches the lowest part 83Yb in the first direction X, the second direction Y, or the horizontal direction.

[0053] The lowest part 83Yb is the portion that protrudes from the outer edge 83Ya in the direction from the toner chamber 430Yc toward the air chamber 430Yd. As shown in Figures 8(a) and 9(b), the lowest part 83Yb is located in the center of the filter 83Y in the first direction Y and the second direction Y. The filter 83Y is made of material molded into the shape described above.

[0054] A discharge pipe 85Y (passage) is provided in the toner chamber 430Yc. In this embodiment, the discharge pipe 85Y is a resin-molded component, but it may also be made of paper or rubber. The discharge pipe 85Y has an inlet 85Ya (first opening) and an outlet 85Yb (second opening), and is a pipe that extends from the inlet 85Ya to the outlet 85Yb. The discharge pipe 85Y is a passage through which the toner T contained in the toner chamber 430Yc is moved toward the discharge port 430Ya1. The discharge pipe 85Y has a first portion 85Y1 which has an inlet 85Ya and extends in a third direction Z, and a second portion 85Y2 which has an outlet 85Yb and extends in a first direction X. The direction in which the first portion 85Y1 extends and the direction in which the second portion 85Y2 extends intersect (orthogonal). The outlet 85Yb of the discharge pipe 85Y is connected to the discharge port 430Ya1. The inlet 85Ya of the discharge pipe 85Y is positioned opposite the lowest part 83Yb, which is part of the filter 83Y, with a gap between them. It is preferable that the inlet 85Ya is close to the filter 83Y. When the amount of toner T in the toner chamber 430Yc becomes low, the toner T, which has been fluidized by the air received from the receiving inlet 430Yb1, moves along the slope of the filter 83Y described above and collects at the lowest part 83Yb. The inlet 85Ya of the discharge pipe 85Y can guide the toner T collected at the lowest part 83Yb of the filter 83Y to the discharge port 430Ya1. This allows the toner T to be efficiently discharged to the outside of the cartridge 430Y even when the amount of toner contained in the toner chamber 430Yc of the cartridge 430Y becomes low.

[0055] The cartridge in this embodiment has a structure that expels toner to the outside of the cartridge using air, and does not require any rotating members such as screws. Therefore, it is possible to create a cartridge with a simple structure and a small number of parts.

[0056] [Toner transport mechanism] This section describes the mechanism by which toner stored in the toner chamber 430Yc of cartridge 430Y is transported to the developing unit PY.

[0057] Air discharged from the pump unit 80 is supplied from the air supply tube 61 through the flow path of the cartridge holder 511 to the air supply port 514. As shown in Figure 5(b), the air is received from the air supply port 514 into the air chamber 430Yd via the inlet 430Yb1 of the cartridge 430Y. This air then increases the air pressure in the air chamber 430Yd, passes through the filter 83Y, and flows into the toner chamber 430Yc. The air that flows into the toner chamber 430Yc penetrates between the toner particles T, causing the toner T to become fluid. The toner T, which has become fluid after mixing with the air, is moved through the discharge pipe 85Y from the inlet 85Ya to the outlet 85Yb by the air received into the air chamber 430Yd via the inlet 430Yb1, and is discharged to the outside of the cartridge 430Y from the outlet 430Ya1.

[0058] As in this embodiment, by providing an air chamber 430Yd, which is a highly sealed space, between the discharge port 80Ya and the filter 83Y, the air discharged from the discharge port 80Ya is efficiently directed to the filter 83Y without being dispersed outside the cartridge 430Y. For example, consider a situation where the toner T in the toner chamber 430Yc agglomerates, such as when the cartridge 430Y is subjected to vibration or left unattended for a long time, and the pressure required to allow air to flow into the cartridge 430Y through the filter 83Y is high. By continuously supplying air from the pump unit 80 to the air chamber 430Yd and increasing the pressure (atmospheric pressure) in the air chamber 430Yd, it becomes possible to supply air through the filter 83Y into the toner chamber 430Yc. Furthermore, by providing the air chamber 430Yd, it is sufficient for the pump unit 80 to generate enough pressure to continuously supply air into the air chamber 430Yd until the pressure is sufficient for air to pass from the filter 83Y into the toner chamber 430Yc. Therefore, no special requirements are made regarding the air discharge speed or discharge volume. Therefore, it becomes possible to use a smaller pump unit, contributing to the miniaturization of the device.

[0059] A tube 62Y (second tube) is provided for the toner transported by air from cartridge 430Y to the developing unit 9Y. Similarly, a tube 62M (first tube) is provided for the toner transported by air from cartridge 430M to the corresponding developing unit 9M. Tubes 62C and 62K are provided for similar purposes. Tubes 62Y, 62M, 62C, and 62K are flexible tubes made of materials such as polyurethane, silicone, nylon, and polyolefin, which have excellent flexibility and toner resistance.

[0060] Tube 62Y has an upstream end 62Yu (third end) attached to the cartridge holder 511 and a downstream end 62Yd (fourth end) attached to the developing unit 9. As shown in Figure 5(b), toner T discharged from the outlet 430Ya1 of cartridge 430Y enters the interior of tube 62Y from the upstream end 62Yu via the receiving port 51a of cartridge holder 511. The toner T that has entered the interior of tube 62Y from the upstream end 62Yu is transported to the downstream end 62Yd by air that is also discharged from the outlet 430Ya1 of cartridge 430Y and flows into the upstream end 62Yu.

[0061] To improve the ability of air to be discharged from the developing unit 9 to the outside, an exhaust filter section PYf is provided on the upper surface of the developing unit 9Y, as shown in Figure 3. The exhaust filter section PYf is a part in the frame that forms the developing unit 9Y in which through holes are provided, and a filter such as nonwoven fabric is provided in the through holes. The toner T that flows into the inside of the developing unit 9Y from the tube 62Y remains in the developing unit 9Y (developing container 3Y), and at least a portion of the air is discharged to the outside of the developing unit 9Y from the exhaust filter section PYf. As a result, the rise in internal pressure inside the developing unit 9Y is further suppressed, and toner T and air flow into the developing unit 9Y from the cartridge 430Y via the tube 62Y.

[0062] In this embodiment, the exhaust filter PYf is provided on the upper surface of the developing unit 9Y downstream in the toner inflow direction in the second direction Y. The exhaust filter may be provided on the side surface of the developing unit 9Y instead of the upper surface.

[0063] The toner supplied into the developing unit 9Y (developing container 3Y) from the end of the developing unit 9Y in the second direction Y is stirred and leveled by the stirring members SY1 and SY2 shown in Figure 5(b). The stirring members SY1 and SY2 may be screws configured to transport the toner in the second direction Y from the end of the developing unit 9Y on the side to which the downstream end 62Yd of the tube 62Y is connected to the end of the developing unit 9Y on the opposite side. Furthermore, depending on the required stirring efficiency of the toner T within the developing unit 9Y, the stirring members may consist of one or more components.

[0064] In configurations such as those for each tube 62 in this embodiment, where the direction of the transport path changes midway, or where the transport path differs for each color, it is preferable to use air as the transport means for transporting the toner. This improves the design flexibility of the transport path compared to using screws or the like as the transport means, and reduces the number of parts because transport components are not required.

[0065] [Tube configuration] The configuration of each tube 62 will now be described. Each tube 62 is positioned to avoid each optical path L output from the laser scanner unit LB, and to shorten the transport path according to the position of each developing container 9 and each cartridge 430. As mentioned above, the developing unit 9Y is configured to be movable between a contact position in which the developing roller 6Y contacts the photosensitive drum 4Y and a separation position in which the developing roller 6 is separated from the photosensitive drum 4 relative to the drum unit 8Y. Furthermore, as shown in Figures 4(b) and 6(a), the upstream end 62Yu (third end) of the tube 62Y is attached to the cartridge holder 511 so as to communicate with the receiving port 511Ya, and the downstream end 62Yd (fourth end) of the tube 62Y is attached to the top of the developing unit 9Y (developing container 3Y) so as to communicate with the receiving port 33Y of the developing container 3Y. Similarly, as shown in Figure 4(b), the upstream end 62Mu (first end) of the tube 62M is attached to the cartridge holder 511 so as to communicate with the inlet 511Ma, and the downstream end 62Md (second end) of the tube 62M is attached to the top of the developing unit 9M (developing container 3M) so as to communicate with the inlet 33M of the developing container 3M.

[0066] Figures 6(a) and 10(a) are cross-sectional and perspective views perpendicular to the second direction Y of the image forming unit 500 in contact state, where each photosensitive drum 4 and each developing roller 6 are in contact. In this contact state, the developing unit 9Y (first developing unit) is in contact position (first contact position), and the developing unit 9M (second developing unit) is in contact position (second contact position). In this state, the developing units 9C and 9K are also in contact state. The separated positions in Figures 6(b) and 10(b) are cross-sectional and top views showing the separated state, where each developing unit 9 has moved (oscillated) from the contact position in Figure 10(a) toward each cartridge 430 in a second direction (separation direction, +X direction). In this state, the developing unit 9Y (first developing unit) is in separated position (first separated position), and the developing unit 9M (second developing unit) is in separated position (second separated position). In this separated state, developing unit 9C and developing unit 9K are also in a separated state.

[0067] As the developing unit 9Y moves from the contact position to the separation position, the upper part of the developing unit 9Y approaches the cartridge holder 511, and the distance in the first direction X between the upper part of the developing unit 9Y and the cartridge holder 511 decreases. Consequently, the tube 62Y moves relative to the developing unit 9Y in the first direction X, and a bent portion 62Ya is formed as shown in Figure 10(b). As the developing unit 9M moves from the contact position to the separation position, the upper part of the developing unit 9M approaches the cartridge holder 511, and the distance in the first direction X between the upper part of the developing unit 9M and the cartridge holder 511 decreases. Consequently, the tube 62M moves relative to the developing unit 9M in the first direction X, and a bent portion 62Ma is formed as shown in Figure 10(b).

[0068] As the developing unit 9Y moves from a contact position to a separation position, the tube 62Y bends, making it less likely for the movement (oscillation) of the developing unit 9Y to be hindered by the tube 62Y. Similarly, as the developing unit 9M moves from a contact position to a separation position, the tube 62M bends, making it less likely for the movement (oscillation) of the developing unit 9M to be hindered by the tube 62M.

[0069] [Low friction material] The configuration of the low-friction member 90 in this embodiment will now be described. When the tube 62Y moves while sliding against the outer surface of the developing container 3Y and the developing container 3M, it is preferable that the frictional resistance between the tube 62Y and the housings of the developing containers 3Y and 3M is small. It is also preferable that the frictional resistance between the tube 62M and the housing of the developing unit 9M is small. The housings of the developing containers 3Y and 3M are formed using acrylonitrile butadiene styrene resin (ABS resin) or polystyrene resin (PS resin), etc. The developing containers 3Y and 3M are formed by injection molding. On the other hand, the tubes 62Y and 62M are formed using polyurethane, silicone, nylon, polyolefin, etc. In this embodiment, the tubes 62Y and 62M are formed by extrusion molding. Therefore, the static friction coefficient of the outer surfaces of tubes 62Y and 62M tends to be large, and if tubes 62Y and 62M come into contact with the outer surface of the developing container 3Y or the outer surface of the developing container 3M, the frictional resistance between them tends to be large, which may hinder the movement of the developing units 9Y and 9M. In this embodiment, low-friction members 90M (first low-friction member, first attachment, first retaining member) are attached to a portion 62Yb (third portion), which is part of the outer surface of tube 62Y, and a portion 62Mb (first portion), which is part of the outer surface of tube 62M. This is to prevent portion 62Yb of tube 62Y and portion 62Mb of tube 62M from coming into contact with portion 3Ma (second portion), which is part of the outer surface of the developing container 3M. Similarly, a low-friction member 90Y is attached to a portion of the outer surface of tube 62Y. This is to prevent tube 62Y from coming into contact with the outer surface of the developing container 3Y.

[0070] The low-friction members 90Y and 90M (hereinafter collectively referred to as low-friction members 90) are formed using polyacetal resin (POM resin), acrylonitrile butadiene styrene resin (ABS resin), polycarbonate resin (PC resin), polycarbonate ABS (PCABS resin), etc. The low-friction members 90 are formed by injection molding. Figure 11(a) is a cross-section of the image forming unit 500 that passes through portion 62Yb of tube 62Y and portion 62Mb of tube 62M and is perpendicular to the first direction X. The first direction X is the direction in which portion 62Yb of tube 62Y and portion 62Mb of tube 62M extend. Figures 11(b) and 11(c) are a perspective view and a front view of the low-friction member 90M as seen from the first direction X, respectively. As shown in Figures 11(a), 11(b), and 11(c), the low-friction member 90M includes a first enclosing portion 90a (first retaining portion) that surrounds portion 62Yb of the tube 62Y from the outside and has a first inner circumferential surface 90a1 centered on the central axis CA1. The low-friction member 90M further includes a second enclosing portion 90c (second retaining portion) that surrounds portion 62Mb of the tube 62Y from the outside and has a second inner circumferential surface 90c1 centered on the central axis CA2. The first enclosing portion 90a and the second enclosing portion 90c are integrally formed. The low-friction member 90M is provided with a first open portion 90b (first opening), which is the portion of the first inner surface 90a1 in the circumferential direction where the first enclosure portion 90a is not provided, and a second open portion 90d (second opening), which is the portion of the second inner surface 90c1 in the circumferential direction where the second enclosure portion 90c is not provided. Portion 62Yb of tube 62Y is press-fitted from the first open portion 90b of the low-friction member 60M into the inside of the first inner surface 90a1 of the first enclosure portion 90a. Similarly, portion 62Mb of tube 62M is press-fitted from the second open portion 90d of the low-friction member 60M into the inside of the inner surface 90c1 of the second enclosure portion 90c.

[0071] The static friction coefficient of the leg portion 90e, which is the outer surface of the low-friction member 90M that can come into contact with portion 3Ma of the developing container 3M, is smaller than the static friction coefficient of portion 62Yb of the tube 62Y and portion 62Mb of the tube 62M. Therefore, as the developing unit 9Y moves from a contact position to a separation position, the leg portion 90e of the low-friction member 90M slides against portion 3Ma of the developing container 3M when the tube 62Y moves relative to the developing container 3M. Thus, the tube 62Y can move smoothly relative to the developing container 3M. Similarly, as portion 62Mb of the tube 62M moves relative to the developing container 3M, the low-friction member 90M slides against portion 3Ma of the developing container 3M, so that the tube 62M can move smoothly relative to the developing unit 9M. Furthermore, the low-friction member 90M holds portion 62Yb of the tube 62Y and portion 62Mb of the tube 62M in the first enclosure portion 90a and the second enclosure portion 90b so that they do not come into contact with each other. Therefore, the movement of the developing units 9Y and 9M between the contact position and the separation position is less likely to be hindered by tubes 62Y and 62M.

[0072] The restricting part 95Y shown in Figure 11(a) protrudes upward from the top surface of the developing container 3Y. The restricting part 95Y restricts the movement of tube 62Y in the -X direction so that tube 62Y does not move in the -X direction on the top surface of the developing container 3Y and block the optical path LY. Similarly, the restricting part 95M protrudes upward from the top surface of the developing container 3M. The restricting part 95M restricts the movement of tube 62M in the -X direction so that tube 62M does not move in the -X direction on the top surface of the developing container 3M and block the optical path LM. When the developing unit 9Y moves from the contact position to the separation position, tube 62Y receives a force in the +X direction from the restricting part 95Y. When the developing unit 9M moves from the contact position to the separation position, tube 62M receives a force in the +X direction from the restricting part 95M.

[0073] A pair of restricting parts 97Y protrude upward from the top surface of the developing container 3Y and are arranged in a second direction Y so as to sandwich the low friction member 90Y. They restrict the movement of the tube 62Y in the second direction Y. The direction in which the developing unit 9Y moves between the contact position and the separation position is the first direction X when viewed in a third direction Z, but since the distance between the pair of restricting parts 97Y in the second direction Y is wider than the width of the low friction member 90Y in the second direction Y, the pair of restricting parts 97Y can move smoothly in the first direction X relative to the low friction member 90. Therefore, the pair of restricting parts 97Y do not easily obstruct the movement of the developing unit 9Y. Similarly, a pair of restricting parts 97M protrude upward from the top surface of the developing container 3M and are arranged in a second direction Y so as to sandwich the low friction member 90M. They restrict the movement of the tube 62Y in the second direction Y. Since the distance between the pair of restricting portions 97M in the second direction Y is wider than the width of the low-friction member 90M in the second direction Y, the pair of restricting portions 97M can move smoothly in the first direction X relative to the low-friction member 90M.

[0074] [Example 2] The structure of the low-friction member 91 according to this embodiment will now be described. Figure 12(a) is a perspective view of the image forming unit 501 in a state where each photosensitive drum 4 and each developing roller 6 are in contact. Figure 12(b) is a perspective view of the image forming unit 501 in a state where each photosensitive drum 4 and each developing roller 6 are separated. The low-friction member 91 is attached to portion 62Cb, which is a part of the outer circumferential surface of the tube 62C, and portion 3Ca, which is a part of the outer surface of the developing unit 9C (developing container 3Y), so that they do not come into contact with each other. Figure 13(a) is a cross-sectional view of the image forming unit 501 passing through portion 62Cb of the tube 62C and perpendicular to the first direction X. Figures 13(b) and 13(c) are a perspective view and a front view of the low-friction member 91 as seen in the first direction X, respectively. When the tube 62C moves relative to the outer surface of the developing container 3C of the developing unit 9C as the developing unit 9C moves between a contact position and a separation position, it is preferable that the frictional resistance between the tube 62C and the developing unit 9C be small. Therefore, in this embodiment, a low-friction member 91 is provided on part 62Cb of the tube 62C. The low-friction member 91 is formed using polyacetal resin (POM resin), acrylonitrile butadiene styrene resin (ABS resin), polycarbonate resin (PC resin), polycarbonate ABS (PCABS resin), etc. The low-friction member 91 is formed by injection molding.

[0075] In Figure 13, the low-friction member 91 has an enclosing portion 91a (holding portion) that surrounds the 62Cb of the tube 62C from the outside and has an inner circumferential surface 91a1 centered on the central axis CA3. The low-friction member 91 further includes an open portion 91b, which is the portion of the inner circumferential surface 91a1 in which the enclosing portion 91a is not provided, and a supported portion 91c that is rotatably supported on the upper surface of the developing container 3C about the rotation axis RA1. The enclosing portion 91a is provided at one end of the low-friction member 91 in the longitudinal direction. The supported portion 91c is provided at the other end of the low-friction member 91 in the longitudinal direction. The portion 62Cb of the tube 62C is press-fitted from the open portion 91b towards the inner circumferential surface 91a1 of the low-friction member 91. The rotation axis RA1 of the low-friction member 91 is configured to extend in a third direction Z, and the central axis CA3 is configured to extend in a first direction X. In other words, the rotation axis RA1 and the central axis CA3 extend in directions perpendicular to each other. When the developing unit 9C moves between the contact position and the separation position, the low-friction member 91 rotates around the rotation axis RA1 with portion 62Cb of the tube 62Y held by the surrounding portion 91a. As the low-friction member 91 is rotated, the bottom portion 91e of the low-friction member 91 slides against portion 3Ca of the developing container 3Y, allowing the tube 62C to move smoothly relative to the developing container 3C. In this embodiment, the low-friction member 91 was provided on the developing container 3C, but it may also be provided on the developing containers 3Y, 3M, and 3K.

[0076] [Example 3] This embodiment uses rotatable rollers 92 (rotating bodies, rollers) instead of low-friction members like those in Embodiments 1 and 2. Figure 14(a) is a perspective view of the image forming unit 503 in a state where each photosensitive drum 4 and each developing roller 6 are in contact. Figure 14(b) is a perspective view of the image forming unit 503 in a state where each photosensitive drum 4 and each developing roller 6 are separated. Rollers 92Y, 92M, and 92C are provided so as to be rotatable relative to the upper surface of the developing container 3Y, the upper surface of the developing container 3M, and the upper surface of the developing container 3C, respectively. A portion of the tube 62Y extending in the first direction X is in contact with rollers 92Y, 92M, and 92C. When the developing unit 9Y is moved in the separation direction (+X direction) from the contact position to the separation position, the tube 62Y bends while moving relative to the developing containers 3Y, 3M, and 3C. At this time, rollers 92Y, 92M, and 92C rotate, allowing tube 62Y to move smoothly relative to developing containers 3Y, 3M, and 3C. Therefore, the movement of tube 62Y relative to developing container 3 has the effect of not hindering the movement of developing unit 9. [Explanation of symbols]

[0077] 1. Image forming apparatus 3. Developing container 4 Photosensitive drum 6. Developing roller 8 Drum Units 9. Developing Unit 72 Main unit of the device 430 cartridges 430a1 outlet 430b Inlet 50 Image forming units 61 Air transport tube 62 Toner transport tubes 80 pumps 90 Low friction member 91 Low friction member 92 Koro X First direction Y Second direction Z Third direction

Claims

1. An image forming apparatus, A toner container that contains toner and has an outlet for discharging toner, The device body includes a main body frame from which the toner container can be attached and detached, the main body frame having a communication port that communicates with the discharge port, Equipped with, The main body of the aforementioned device is A drum unit having a photosensitive drum, A developing unit comprising a developing frame body including a receiving port for receiving toner and a toner storage section for storing toner, and a developing roller that carries the toner stored in the storage section and supplies toner to the photosensitive drum, wherein the developing unit is configured to be movable relative to the photosensitive drum and the main frame body between a contact position in which the developing roller is in contact with the photosensitive drum and a separation position in which the developing roller is separated from the photosensitive drum, A passage through which toner discharged from the discharge port of the toner container is transported from the communication port to the receiving port, having a first end connected to the main body frame so as to communicate with the communication port, and a second end connected to the developing unit so as to communicate with the receiving port, the passage extending from the first end to the second end, Equipped with, The passage is composed of a flexible tube and is configured to bend between the first end and the second end as the developing unit moves between the contact position and the separation position. An image forming apparatus characterized by the following features.

2. When a part of the outer surface of the tube and a part of the outer surface of the developing frame are designated as a first part and a second part, respectively, the apparatus body has a low-friction member attached to the first part of the tube. The outer surface of the low-friction member that can come into contact with at least the second portion has a lower static friction coefficient than the first portion of the tube. The image forming apparatus according to feature 1.

3. The low-friction member has an inner circumferential surface that surrounds the first portion from the outside in a cross-section perpendicular to the direction in which the tube extends and passing through the first portion. The first portion of the tube is press-fitted into the inner side of the inner circumferential surface of the low-friction member. The image forming apparatus according to feature 2.

4. The low-friction member is configured to move relative to the developing frame while holding the first portion of the tube. The image forming apparatus according to feature 2.

5. The low-friction member is provided with a holding portion at one end in the longitudinal direction for holding the first portion of the tube, and a supported portion at the other end in the longitudinal direction that is movably supported relative to the developing frame. The image forming apparatus according to feature 4.

6. The low-friction member is supported by the developing frame such that the supported portion is rotatable about a rotation axis relative to the developing frame. The image forming apparatus according to feature 5.

7. The low-friction member has an inner circumferential surface that surrounds the first portion of the tube from the outside, in a cross section perpendicular to the direction in which the tube extends and passing through the first portion, with the inner circumferential surface centered on the central axis. The aforementioned central axis extends in a direction intersecting the aforementioned axis of rotation. The image forming apparatus according to feature 6.

8. When the toner container, the discharge port, the communication port, the receiving port, the housing section, the developing frame, the developing roller, the photosensitive drum, the drum unit, the developing unit, the contact position, the separation position, and the tube are respectively defined as a first toner container, a first discharge port, a first communication port, a first receiving port, a first housing section, a first developing frame, a first developing roller, a first photosensitive drum, a first drum unit, a first developing unit, a first contact position, a first separation position, and a first tube, A second toner container for storing toner, comprising a second toner container provided with a second discharge port and detachable from the main body frame, The main frame is provided with a second communication port that communicates with the second discharge port. The main body of the aforementioned device is A second drum unit having a second photosensitive drum, A second developing unit comprising a second developing frame body including a second receiving port for receiving toner and a second storage section for storing toner, and a second developing roller for carrying the toner stored in the second storage section and supplying toner to the second photosensitive drum, wherein the second developing unit is configured to be movable relative to the second photosensitive drum and the main frame body between a second contact position in which the second developing roller contacts the second photosensitive drum and a second separation position in which the second developing roller separates from the second photosensitive drum, A flexible second tube having a third end connected to the main frame so as to communicate with the second communication port, and a fourth end connected to the second developing unit so as to communicate with the second receiving port, the second tube through which toner discharged from the second discharge port passes when transported from the second communication port to the second receiving port, It has, The second tube is configured to bend between the third end and the fourth end as the second developing unit moves between the second contact position and the second separation position. The image forming apparatus according to feature 1.

9. When a part of the outer surface of the first tube, a part of the outer surface of the first developing frame, and a part of the outer surface of the second tube are designated as the first part, the second part, and the third part, respectively, the apparatus body has low-friction members attached to the first part of the first tube and the third part of the second tube. The outer surface of the low-friction member that can come into contact with at least the second portion has a lower static friction coefficient than either the first portion of the first tube or the third portion of the second tube. The image forming apparatus according to feature 8.

10. The low-friction member is In a cross-section perpendicular to the direction in which the first tube extends and passing through the first portion of the first tube, a first enclosure portion surrounds the first portion of the first tube from the outside, In a cross-section perpendicular to the direction in which the second tube extends and passing through the third portion of the second tube, a second enclosure portion surrounds the third portion of the second tube from the outside, It has, The first enclosure and the second enclosure are formed integrally. The image forming apparatus according to feature 9.

11. The apparatus body has a roller that is rotatably supported by the developing frame, The roller rotates in a direction that moves the tube relative to the developing frame as the developing unit moves between the contact position and the separation position. The image forming apparatus according to feature 1.

12. The tube is formed of at least one of polyurethane, silicone, nylon, and polyolefin. The image forming apparatus according to feature 1.

Images