Filter holding device, developing device, process cartridge, and image forming apparatus

Abstract

The present invention relates to a filter holding device, a developing device, a process cartridge, and an image forming apparatus. The filter holding device includes an opening portion and a filter. The opening portion connects an inside of the filter holding device with an outside of the filter holding device and has a rim extending in a communicating direction from the inside of the filter holding device toward the outside of the filter holding device. The filter is disposed in the opening portion and has a first side and a second side. The first side faces the inside of the filter holding device. The second side faces the outside of the filter holding device. In a state where the filter is arranged in the opening portion, the filter has a larger weight density per unit volume at the second side facing the outside of the filter holding device than at the first side facing the inside of the filter holding device.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to a filter holding device that provides a filter in an opening portion, a developing device that contains toner, a process cartridge, and an image forming apparatus including the filter. BACKGROUND

[0002] In the past, in a developing device provided in an image forming apparatus such as a copier or a printer, it is known that a filter is provided in an opening portion formed in an upper portion of a developing cartridge body for the purpose of preventing toner from flying due to an increase in internal pressure in the developing device (for example, Japanese Unexamined Patent Application Publication No. 2014-178347). Specifically, in the developing device in Japanese Unexamined Patent Application Publication No. 2014-178347, even if the internal pressure inside the developing device is to rise, air inside the developing device is discharged to the outside of the developing device through the opening portion provided with the filter, thereby suppressing the rise in internal pressure. Then, when the air inside the developing device is discharged to the outside of the developing device, even if toner floating in the developing device is to be discharged to the outside of the developing device along with the air, the toner is collected by the filter. Therefore, the flying of toner to the outside of the device is suppressed.

[0003] LIST OF CITATIONS

[0004] PATENT LITERATURE

[0005] [Patent Literature 1]

[0006] Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2014-178347 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In such conventional technology, there is a possibility that air (discharge object) in the device leaks from the side surface of the filter along with toner (collection object). In this case, the function of the filter cannot be sufficiently exerted, and toner (collection object) flies to the outside of the device. The present disclosure is to solve the above problem and provide a filter holding device, a developing device, a process cartridge, and an image forming apparatus that reduce the defect in which a discharge object in the device is discharged to the outside of the device along with a collection object.

[0009] SOLUTION TO PROBLEM

[0010] A filter holding device according to an embodiment of the present disclosure includes an opening portion and a filter. The opening portion connects an inner side of the filter holding device with an outer side of the filter holding device and has a rim extending in a communicating direction from the inner side of the filter holding device toward the outer side of the filter holding device. The filter is disposed in the opening portion and has a first side and a second side. The first side faces the inner side of the filter holding device. The second side faces the outer side of the filter holding device. The filter has a weight density per unit volume that is greater on the second side than on the first side in a state where the filter is disposed in the opening portion.

[0011] Effects of the Invention

[0012] According to the present disclosure, there are provided a filter holding device, a developing device, a process cartridge, and an image forming apparatus that reduce a defect in which a discharge object is discharged to an outer side of the device together with a collection object. BRIEF DESCRIPTION OF DRAWINGS

[0013] The drawings are intended to explain exemplary embodiments of the present invention and should not be construed as limiting the scope thereof. Unless explicitly stated, the drawings should not be regarded as drawn to scale. In addition, in all the drawings, the same or similar reference numerals denote the same or similar components.

[0014] Figure 1 A schematic diagram of an overall configuration of an image forming apparatus according to an embodiment of the present disclosure is shown.

[0015] Figure 2A A cross-sectional view of an image forming unit according to an embodiment of the present disclosure is shown. Figure 2B Another cross-sectional view of an image forming unit according to an embodiment of the present disclosure is shown.

[0016] Figure 3 A configuration diagram of a developing device in a longitudinal direction is shown.

[0017] Figure 4A An enlarged cross-sectional view of a state in which a filter is disposed in an opening portion of a developing device is shown. Figure 4B An enlarged cross-sectional view of a state before a filter is disposed in an opening portion of a developing device is shown.

[0018] Figure 5A A cross-sectional view of a filter according to an embodiment of the present disclosure is shown. Figure 5B A cross-sectional view of a filter according to another embodiment of the present disclosure is shown.

[0019] Figure 6 An enlarged view of a state in which a filter is disposed in an opening portion of a developing device as a first modified example is shown.

[0020] Figure 7The image shown is an enlarged view of a second variation in which a filter is installed at the opening of the developing apparatus.

[0021] Figure 8 The image shown is an enlarged view of the state in which a filter is installed at the opening of the developing apparatus as a third variation.

[0022] Figure 9 The image shown is an enlarged view of the main part of the developing apparatus as the fourth variation.

[0023] Figure 10 The image shown is an enlarged view of the state in which a filter is installed at the opening of the developing apparatus as the fifth variation.

[0024] Figure 11A The image shown is an enlarged view of a state in which a filter is provided at the opening of a developing apparatus according to another embodiment. Figure 11B The image shown is... Figure 11A A schematic diagram of the state of the developing device before the filter is installed at the opening.

[0025] Figure 12 The image shown is an enlarged view of the state in which a filter is installed at the opening of the developing apparatus as a sixth variation.

[0026] Figure 13 The image shown is an enlarged view of the state in which a filter is installed at the opening of the developing apparatus as the seventh variation.

[0027] Figure 14 The image shown is an enlarged view of the state in which a filter is installed at the opening of the developing apparatus as the 8th variation.

[0028] Figure 15A The image shown is a magnified view of the filter as the 9th variation, both longitudinally and laterally. Figure 15B The image shown is an enlarged view of a filter installed at the opening of the developing apparatus along the long side, as the 9th variation. Detailed Implementation

[0029] The terms used herein are for illustrative purposes only and are not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Specific terms have been used for clarity in describing the embodiments illustrated in the accompanying drawings. However, the disclosure of this specification is not intended to be limited to the selected specific terms, and it should be understood that each specific element includes all technical equivalents that have similar functionality, operate in a similar manner, and achieve similar results.

[0030] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, the same reference numerals will be used for the same parts or equivalents, and the descriptions of these components will be simplified or omitted.

[0031] The overall configuration and operation of the image forming apparatus 1 to which the embodiment of the present disclosure relates will be described below with reference to Figure 1 The image forming apparatus 1 to which the embodiment of the present disclosure relates is a tandem type multi-color image forming apparatus in which the process cartridges 20Y, 20M, 20C, and 20BK face the intermediate transfer belt 40 and are arranged in parallel with each other. As shown in Figure 1 , a developing device 26 (see Figure 2A ) as a filter holding device (a device having a filter) is disposed to face the photosensitive drum 21 in each of the process cartridges 20Y, 20M, 20C, and 20BK.

[0032] In Figure 1 , the image forming apparatus 1 as a main body of a color copying machine in the embodiment includes a document conveyance device 2, a scanner 3 as a document reading device, and a writer 4 as an exposure device. The document conveyance device 2 conveys a document to the scanner 3. The scanner 3 reads image data of the document. The writer 4 emits laser light in accordance with the input image data. In addition, the image forming apparatus 1 includes the process cartridges 20Y, 20M, 20C, and 20BK to form yellow, magenta, cyan, and black toner images on respective surfaces of the photosensitive drums 21 (see Figure 2A ), respectively, and the intermediate transfer belt 40 on which the yellow, magenta, cyan, and black toner images are transferred and superimposed. The image forming apparatus 1 further includes a sheet supply portion 61 for housing a sheet P such as a paper sheet, a secondary transfer roller 65 for transferring the toner image formed on the intermediate transfer belt 40 to the sheet P, and a fixing device 66 for fixing the unfixed toner image to the sheet P. The image forming apparatus 1 further includes a toner container 70 for supplying various colors of toner to the developing devices 26 of the plurality of process cartridges 20Y, 20M, 20C, and 20BK, and a waste toner container 80 for collecting toner collected by the cleaning device 23 (see FIG. 2) or unfixed toner collected by an intermediate transfer belt cleaner 81.

[0033] Each of the process cartridges 20Y, 20M, 20C, and 20BK includes a Figure 2A and 2BThe photosensitive drum 21, the charging device 22, and the cleaning device 23 as image bearers are integrated as a single unit as shown. The process cartridges 20Y, 20M, 20C, and 20BK as consumables are replaced by new ones when they are exhausted in the main body of the image forming apparatus 1. The developing device 26 is disposed to face the photosensitive drum 21 in each of the process cartridges 20Y, 20M, 20C, and 20BK. The developing device 26 as a consumable is replaced by a new one when it is exhausted in the main body of the image forming apparatus 1. As different operations, the operator can independently perform the mounting and removal operations of the developing device 26 with respect to the main body of the image forming apparatus 1 and the mounting and removal operations of the process cartridges 20Y, 20M, 20C, and 20BK with respect to the main body of the image forming apparatus 1. In the process cartridges 20Y, 20M, 20C, and 20BK, toner images (yellow, magenta, cyan, and black) are formed on the respective photosensitive drums 21 as image bearers.

[0034] The operation of the image forming apparatus 1 that forms toner images of general colors will be described below. The conveying roller of the document conveying device 2 conveys a document from a document table to an exposure glass of the scanner 3. The scanner 3 optically scans image data of the document on the exposure glass. Yellow, magenta, cyan, and black image data are sent to the writing device 4. The writing device 4 irradiates the photosensitive drum 21 of the corresponding process cartridge 20Y, 20M, 20C, and 20BK with a laser beam (as exposure light) L based on the yellow, magenta, cyan, and black image data, respectively (see Figure 2A and 2B ).

[0035] Each of the four photosensitive drums 21 is rotated clockwise (in the direction indicated by the arrow in Figure 1 Figure 2A ). The surface of the photosensitive drum 21 is uniformly charged at a position where the photosensitive drum 21 faces the charging device 22 as a charging roller (charging process). Thus, the surface of the photosensitive drum 21 is charged to a certain potential. When the charged surface of the photosensitive drum 21 reaches a position where the laser beam L emitted from the writing device 4 is received, an electrostatic latent image based on the image data is formed on the surface of the photosensitive drum 21 (exposure process).

[0036] The laser beam L corresponding to the yellow image data is irradiated to the photosensitive drum 21 in the yellow process cartridge 20Y among the four process cartridges 20Y, 20M, 20C, and 20BK. Figure 1 ​the first from the left in the yellow process cartridge 20Y. The high-speed rotating polygon mirror deflects the laser beam L for yellow so that the laser beam L scans the surface of the photosensitive drum 21 in the direction of the rotation axis of the photosensitive drum 21 (i.e., the main scanning direction). Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 21 charged by the charging device 22. Similarly, the laser beam L corresponding to the cyan image data is deflected from the left in the cyan process cartridge 20C to the surface of the photosensitive drum 21 in the cyan process cartridge 20C, thereby forming an electrostatic latent image of cyan on the surface of the photosensitive drum 21. The laser beam L corresponding to the magenta image data is deflected from the left in the magenta process cartridge 20M to the surface of the photosensitive drum 21 in the magenta process cartridge 20M, thereby forming an electrostatic latent image of magenta on the surface of the photosensitive drum 21. The laser beam L corresponding to the black image data is deflected from the left in the black process cartridge 20BK to the surface of the photosensitive drum 21 in the black process cartridge 20BK, thereby forming an electrostatic latent image of black on the photosensitive drum 21. Figure 1 Figure 1 Figure 1

[0037] Then, the surface of the photosensitive drum 21 having the electrostatic latent image reaches a position facing the developing device 26. The developing device 26 supplies toners of various colors to the surface of the photosensitive drum 21 and develops the electrostatic latent image on the photosensitive drum 21 into a toner image (developing process). Subsequently, the surface of the photosensitive drum 21 after the developing process reaches a position facing the intermediate transfer belt 40. The primary transfer rollers 24 are disposed at positions where the photosensitive drum 21 faces the intermediate transfer belt 40 and abut against the inner circumferential surface of the intermediate transfer belt 40. At the positions of the primary transfer rollers 24, the toner images on the photosensitive drum 21 are sequentially transferred and superimposed on the intermediate transfer belt 40, thereby forming a multicolor toner image thereon (primary transfer process).

[0038] After the primary transfer process, the surface of the photosensitive drum 21 reaches a position facing the cleaning device 23. The cleaning device 23 collects untransferred toners remaining on the photosensitive drum 21 (cleaning process). The untransferred toners collected in the cleaning device 23 pass through the waste toner transport path and are collected as waste toners in the waste toner container 80. Subsequently, the residual electric potential of the surface of the photosensitive drum 21 is removed at a position facing the electric elimination device, and the series of image forming processes performed on the photosensitive drum 21 is completed.

[0039] Meanwhile, the surface of the intermediate transfer belt 40 on which the single-color toner images on the photosensitive drums 21 are superimposed is conveyed in the direction of the arrow A at a constant speed in synchronization with the rotation of the intermediate transfer belt 40. Figure 1 ​​​The intermediate transfer belt 40 moves in the direction indicated by the middle arrow and reaches a position facing the secondary transfer roller 65. The secondary transfer roller 65 secondarily transfers the multi-color toner image on the intermediate transfer belt 40 to the sheet P (secondary transfer process). After the secondary transfer process, the surface of the intermediate transfer belt 40 reaches a position facing the intermediate transfer belt cleaning device 81. The intermediate transfer belt cleaning device 81 collects the untransferred toner on the intermediate transfer belt 40 to complete a series of transfer processes on the intermediate transfer belt 40. The untransferred toner collected in the intermediate transfer belt cleaning device 81 passes through the waste toner transport path and is collected as waste toner into the waste toner container 80.

[0040] The sheet P is transported from the sheet supply portion 61 to the position of the secondary transfer roller 65 via the registration roller pair 64. Specifically, the supply roller 62 supplies the sheet P from the top of the multiple sheets P housed in the sheet supply portion 61. The sheet P is transported to the registration roller pair 64 through the sheet transport path. The sheet P that has reached the registration roller pair 64 is transported toward the position of the secondary transfer roller 65 in alignment with the arrival timing of the multi-color toner image on the intermediate transfer belt 40.

[0041] Subsequently, the sheet P on which the multi-color image is transferred is transported to the fixing device 66. The fixing device 66 includes a fixing roller and a pressure roller that are pressed against each other. In the nip between the fixing roller and the pressure roller, the multi-color toner image is fixed to the sheet P. After the fixing process, the output roller pair 69 discharges the sheet P as an output image outside the main body of the image forming apparatus 1. The discharged sheet P is stacked on the output tray 5 to complete a series of image forming processes.

[0042] Next, the image forming apparatus will be described in detail with reference to Figure 2A and Figure 3 . Four image forming units provided in the main body of the image forming apparatus 1 (see Figure 1 ) have the same configuration except for the color of the toner used in the image forming process. Therefore, in the drawings, the components of the image forming units such as the process cartridges and the developing devices do not have the suffixes Y, M, C, and BK that indicate the color of the toner.

[0043] As Figure 2AAs shown, the processing cartridge 20 mainly includes a photosensitive drum 21 as an image carrier, a charging device 22, and a cleaning device 23, which are housed as a single unit within the cartridge body of the processing cartridge 20. The photosensitive drum 21 is an organic photosensitive material designed with negative polarity and includes a photosensitive layer formed on a drum-shaped conductive support. The charging device 22 is a charging roller including a conductive core and an elastic layer of moderate resistance covering the conductive core. A power source applies a predetermined voltage to the charging device 22, which serves as the charging roller. The charging device 22 uniformly charges the surface of the photosensitive drum 21, which faces the charging device 22. The cleaning device 23 includes a cleaning blade 23a and a cleaning roller 23b that abut against the photosensitive drum 21. For example, the cleaning blade 23a is made of rubber such as polyurethane rubber and abuts against the surface of the photosensitive drum 21 at a predetermined angle and with a predetermined pressure. The cleaning roller 23b is a brush roller with bristles arranged around the core.

[0044] like Figure 2A and Figure 3 As shown, the developing apparatus 26 mainly includes a developing roller 26a (serving as a developer carrier), a first conveying screw 26b1 facing the developing roller 26a (serving as a first conveying member), an isolation member 26e, a second conveying screw 26b2 facing the first conveying screw 26b1 via the isolation member 26e (serving as a second conveying member), and a scraper 26c facing the developing roller 26a to adjust the amount of developer carried on the developing roller 26a (serving as a developer adjusting member). In this embodiment, the developing apparatus 26 also serves as a filter holding device for holding the filter 26t (toner filter), which will be described in detail later.

[0045] The developing unit 26 stores a two-component developer comprising a carrier and a toner. The developing roller 26a is positioned opposite the photosensitive drum 21 with a small gap, thereby forming the developing area. Figure 3 As shown, the developing roller 26a includes an inner fixed magnet 26a1 and a sleeve 26a2 that rotates around the magnet 26a1. The magnet 26a1 generates multiple poles (magnetic poles) around the outer peripheral surface of the developing roller 26a.

[0046] The first conveying screw 26b1 and the second conveying screw 26b2 act as conveying components to convey the developer stored in the developing apparatus 26 along the long side direction, thereby forming a mixture of... Figure 3the dashed arrow in FIG. 26 indicates a circulation path. That is, the first conveying screw 26b1 forms the first conveying path B1, and the second conveying screw 26b2 forms the second conveying path B2. The circulation path of the developer includes the first conveying path B1 and the second conveying path B2. The partition member 26e is an inner wall and separates the first conveying path B1 from the second conveying path B2, which communicate with each other via the first communication opening 26f and the second communication opening 26g provided at both ends in the longitudinal direction of the first conveying path B1 and the second conveying path B2. Specifically, referring to Figure 3 In the conveying direction of the developer, the upstream end of the first conveying path B1 communicates with the downstream end of the second conveying path B2 via the first communication opening 26f. Also, in the conveying direction of the developer, the downstream end of the first conveying path B1 communicates with the upstream end of the second conveying path B2 via the second communication opening 26g. That is, the partition member 26e is disposed along the circulation path except for both end portions in the length direction of the circulation path. The first conveying screw 26b1 in the first conveying path B1 is disposed facing the developing roller 26a. The second conveying screw 26b2 of the second conveying path B2 is disposed facing the first conveying screw 26b1 of the first conveying path B1 with the partition member 26e interposed therebetween. The first conveying screw 26b1 supplies the developer to the developing roller 26a and collects the developer separated from the developing roller 26a after the developing process while conveying the developer in the longitudinal direction of the developing device 26. The second conveying screw 26b2 stirs and mixes the fresh developer supplied from the toner supply inlet 26d with the developer conveyed from the first conveying path B1 after the developing process while conveying the developer and the fresh developer in the longitudinal direction of the developing device 26. In the present embodiment, the first conveying screw 26b1 and the second conveying screw 26b2 are horizontally and parallelly disposed. The first conveying screw 26b1 and the second conveying screw 26b2 each have a shaft and a spiral blade wound around the shaft.

[0047] In the present embodiment, the developing device 26 has, as a housing, two developing box bodies (an upper developing box 26k and a lower developing box 26j) capable of being divided vertically and is covered by the two developing box bodies. The developing roller 26a, the first conveying screw 26b1, and the second conveying screw 26b2 are rotatably held in the lower developing box 26j. The doctor blade 26c is also held in the lower developing box 26j. Also, in the upper developing box 26k, as will be described later, a filter 26t is disposed in an opening portion 26k1. The upper developing box 26k is detachably attached to the lower developing box 26j by a fastening screw or the like in a state in which the developing roller 26a, the first conveying screw 26b1, the second conveying screw 26b2, and the doctor blade 26c are provided.

[0048] Reference will now be made to Figure 2A and Figure 3The above-described image forming process will be described in more detail focusing on the developing process. The developing roller 26a rotates in the direction indicated by the arrow in Figure 2A As shown in Figure 2A and Figure 3 , the first conveying screw 26b1 and the second conveying screw 26b2 are arranged to face each other with the partition member 26e interposed therebetween and rotate in the directions indicated by the arrows in Figure 2A and Figure 3 . The toner is supplied from the toner container 70 to the toner supply inlet 26d (serving as an inlet opening) via a toner supply path. When the first conveying screw 26b1 and the second conveying screw 26b2 rotate in the respective directions indicated by Figure 2A , the developer stored in the developing device 26 is circulated along the longitudinal direction of the developing device 26 (the direction indicated by the dotted arrow in Figure 3 ) together with the supplied toner while being stirred and mixed with the supplied toner. The toner is charged by being rubbed against the carriers in the developer and is electrostatically attracted to the carriers. Then, the toner is drawn onto the developing roller 26a together with the carriers by a developer draw electrode generated on the developing roller 26a. The developer carried on the developing roller 26a is conveyed to a position facing the doctor blade 26c in the counterclockwise direction indicated by the arrow in Figure 2A . The doctor blade 26c regulates the amount of the developer on the developing roller 26a to an appropriate amount at this position. Subsequently, the rotation of the sleeve 26a2 conveys the developer to the developing region of the developing roller 26 facing the photosensitive drum 21. Due to the action of the electric field generated in the developing region, the toner in the developer is attracted to the latent electrostatic image formed on the photosensitive drum 21. Thereafter, as the sleeve 26a2 rotates, the developer remaining on the developing roller 26a reaches above the first conveying path B1 and is separated from the developing roller 26a. The electric field in the developing region is formed by a prescribed voltage (in other words, a developing bias) applied to the developing roller 26a by a developing power source and a surface potential (in other words, a latent image potential) formed on the photosensitive drum 21 in the charging process and the exposure process.

[0049] When the toner in the developing device 26 is consumed, the toner in the toner container 70 is supplied to the developing device 26 from the toner supply inlet 26d via a toner replenishment path. The toner consumption in the developing device 26 is detected by a toner concentration sensor that magnetically detects the toner concentration (i.e., the ratio of the toner in the developer) of the developer in the developing device 26. The toner supply inlet 26d is provided above the end portion of the second conveying screw 26b2 (the second conveying path B2) in the longitudinal direction (the left-right direction in Figure 3 ) and is disposed above the second conveying screw 26b2.

[0050] The configuration and operation of the developing device 26 as the filter holding device according to the present embodiment will be described in more detail below. For example, as shown inFigure 2A and 4A As shown in FIG. 6, the developing device 26 in the present embodiment functions as a filter holding device in which the filter 26t is disposed in the opening portion 26kl connecting the inside of the filter holding device with the outside of the filter holding device. Specifically, the opening portion 26kl (ventilation path) that penetrates the inside and the outside is formed on the top surface of the upper developing cartridge 26k (housing) of the developing device 26. The filter 26t is disposed in a manner to close the opening portion 26kl. The filter 26t collects toner as powder and ventilates the developing device 26. In other words, the opening portion 26kl (ventilation path) for sending air from the inside to the outside of the developing device 26 is formed in the upper developing cartridge 26k. The filter 26t is disposed in the opening portion 26kl as a mounting portion. The wire mesh constituting the filter 26t has a mesh size smaller than the particle diameter of the toner T or the carrier C, and thereby only air is allowed to pass therethrough. In the present embodiment, the opening portion 26kl is opened in a substantially rectangular shape. The filter 26t in a single body state is formed in a substantially rectangular shape.

[0051] The gap H (cartridge gap) between the developing roller 26a and the upper developing cartridge 26k on the downstream side of the developing area is set in a range of 0.6 mm to 1.0 mm. In addition, if the cartridge gap H is less than 0.6 mm, the developer placed on the developing roller 26a cannot be smoothly transported through the cartridge gap H between the developing roller 26a and the upper developing cartridge 26k after the developing process. Therefore, the developer is likely to leak to the outside of the developing device 26. On the other hand, when the cartridge gap H is greater than 1.0 mm, the developer placed on the developing roller 26a is not likely to be in sliding contact with the inner surface of the upper developing cartridge 26k, and almost no suction airflow toward the inside of the developing device 26 due to pumping action is generated. As a result, toner scattering from the developing device 26, that is, scattering of toner to the periphery of the developing area is likely to occur. Therefore, by keeping the cartridge gap H in an appropriate range, it is possible to reduce the leakage of the developer and the scattering of the toner. Furthermore, due to the suction airflow through the above-described cartridge gap H, the internal pressure of the developing device 26 is likely to increase, and in the case where the internal pressure increases, scattering of toner from the gap of the developing device 26 is likely to occur. On the other hand, in the present embodiment, since the opening portion 26kl in which the cover filter 26t is disposed is provided to collect the toner T, ventilation of only air is performed while preventing the toner T from scattering to the outside. As a result, the increase in the internal pressure of the developing device 26 is suppressed. That is, this configuration prevents scattering of toner due to the increase in the internal pressure of the developing device 26.

[0052] In the present embodiment, when the filter 26t is in a single body state (a state) in which the filter 26t is not disposed in the opening portion 26kl, Figure 4B the first side (the side of the opening portion 26kl) of the filter 26t is in contact with the opening portion 26kl. In the present embodiment, the filter 26t is in a single body state in which the filter 26t is not disposed in the opening portion 26kl. In this case, the first side (the side of the opening portion 26kl) of the filter 26t is in contact with the opening portion 26kl. In the present embodiment, the filter 26t is in a single body state in which the filter 26t is not disposed in the opening portion 26kl. In this case, the first side (the side of the opening portion 26kl) of the filter 26t is in contact with the opening portion 26kl. Figure 4BThe weight density per unit volume of the lower side is higher than that of the second side. Figure 4B The weight density per unit volume is low on the upper side. That is, when the filter 26t is in a single state without external force acting on it, the weight density per unit volume in the filter 26t is non-uniform. Parts with low weight density and parts with high weight density are formed in the ventilation direction (connection direction). In other words, the filter 26t has a gradient in weight density per unit volume.

[0053] More specifically, in this embodiment, the filter 26t has a two-layer structure. When the filter 26t is in a single-layer state not disposed in the opening 26k1, on the first side of the filter 26t ( Figure 4B On the lower side) a low-density portion 26t2 with low weight density per unit volume is formed, on the second side of the filter 26t. Figure 4B The filter 26t has a high-density section 26t1 with a high weight density per unit volume on its upper side. That is, in the filter 26t, the low-density section 26t2 on the first side (upstream side in the ventilation direction) has a coarser mesh and is more porous, while the high-density section 26t1 on the second side (downstream side in the ventilation direction) has a denser mesh. Therefore, when the filter 26t according to this embodiment is in a single-unit state, the toner collection capacity of the high-density section 26t1 is higher than that of the low-density section 26t2.

[0054] In the developing apparatus 26 of this embodiment, the opening 26k1 has a communication direction (ventilation direction) from the inside of the developing apparatus 26 to the outside of the developing apparatus 26. Figure 2A and Figure 4A The filter 26t has an opening 26k10 extending vertically in the direction of the developing apparatus 26, such that the first side (having a low weight density) is located on the inner side facing the developing apparatus 26. Figure 4A The lower side of the middle), and the second side (with high weight density) is located on the outer side facing the developing device 26. Figure 4A (The upper side of the middle). At least a portion of the filter 26t disposed in the opening 26k1 abuts against the edge 26k10 and in a direction intersecting the communication direction (i.e., Figure 4A The filter 26t is compressed along the direction of the black arrow in the image. Specifically, the filter 26t is compressed along the second side (the downstream side of the ventilation direction) via the edge 26k10. Figure 4A The state of compression is configured in the opening 26k1 in the direction indicated by the black arrow (crossing direction). More specifically, as... Figure 4A As shown, the filter 26t has a high-density section 26t1 passing through the edge 26k10 in... Figure 4A The state of compression is configured in the opening 26k1 in the direction indicated by the black arrow (crossing direction). That is, inFigure 4A The image shows, in two dimensions, the state in which the filter 26t (high-density portion 26t1) is compressed and configured (fitted) within the opening 26k1. However, in reality, the filter 26t (high-density portion 26t1) is compressed from all sides by abutting against the substantially rectangular edge 26k10.

[0055] More specifically, such as Figure 4B As shown, the length N of the filter 26t in the intersecting direction, which intersects the connecting direction, is set to be greater than either the opening width M1 or M2 (length in the intersecting direction) of the opening 26k1 in the single-unit state (N>M2>M1). Figure 4A As shown, the filter 26t is provided in close contact with the opening 26k1 in a state of being compressed according to the shape of the opening 26k1. That is, the high-density portion 26t1 of the filter 26t provided in the opening 26k1 is compressed with a high compression ratio.

[0056] In the developing apparatus 26 of this embodiment, since the filter 26t is configured to be in close contact with the opening 26k1, the defect of air (exhaust object) and toner (collection object) leaking together from the lateral side of the filter 26t (between the filter 26t and the opening 26k1) is reduced. Therefore, the function of the filter 26t is fully performed, and the defect of toner (collection object) scattering to the outside of the developing apparatus 26 is mitigated. In particular, since the filter 26t has a portion with high weight density per unit volume and easy adhesion, the adhesion of the opening 26k1 in this portion is at least ensured. Therefore, the above-mentioned effects can be obtained. The filter 26t is formed such that the weight density increases from the upstream side to the downstream side in the ventilation direction (communication direction). This configuration is conducive to forming an airflow from the inside to the outside of the developing apparatus 26. Therefore, the increase in internal pressure in the developing apparatus 26 can be effectively suppressed. The overall toner collection performance of the filter 26t can be improved, and the filter 26t is not easily clogged. With the filter 26t positioned at the opening 26k1 (in actual use), the portion with a high weight density per unit volume (high-density portion 26t1) is compressed, further increasing its weight density. The relative weight densities of the high-density portion 26t1 and the low-density portion 26t2 are maintained.

[0057] In the developing apparatus 26 of this embodiment, the edge 26k10 of the opening 26k1 is formed such that the opening area of ​​the opening 26k1 increases from the outside to the inside of the developing apparatus 26 (from...). Figure 4AThe edge 26k10 increases continuously from the upper side to the lower side. That is, relative to the discharge direction (ventilation direction) in which air is discharged to the outside of the developing device 26, the edge 26k10 is inclined (forming an inclined surface in the edge 26k10) from the downstream side to the upstream side away from the center of the opening in the discharge direction. This configuration of the edge 26k10 allows the high-density portion 26t1, which easily improves the adhesion to the edge 26k10, to be compressed at a higher compression ratio. As a result, the adhesion between the filter 26t and the opening 26k1 can be improved. With the above configuration, the filter 26t can be easily assembled and removed from one side relative to the upper developing cartridge 26k in the removed state from the developing device 26. Furthermore, the inclined upper end of the edge 26k10 serves as a limiting part to prevent the filter 26t from falling off to the outside of the developing device 26.

[0058] In the developing apparatus 26 of this embodiment, the stop 26r is installed to detachably abut against the first side of the filter 26t facing the inside of the developing apparatus 26 (the part with low weight density, i.e., the low density part 26t2), so that the filter 26t will not fall into the developing apparatus 26 from the opening 26k1 (edge ​​26k10).

[0059] Specifically, when installing a 26t filter, such as Figure 4B As shown, filter 26t in Figure 4B The white arrow moves in the direction starting from below the upper developing chamber 26k (opening 26k1). For example... Figure 4A As shown, the filter 26t is embedded in the opening 26k1. To prevent the filter 26t from falling downwards, the stop 26r is fixed (screw tightened) to the upper developing cartridge 26k by screws 90 to hold the filter 26t from below. Then, the upper developing cartridge 26k, which has the filter 26t (and the stop 26r), is installed onto the developing apparatus 26 (lower developing cartridge 26j). In this embodiment, a plate-shaped member with an opening on the inside is used as the stop 26r. The stop 26r is not limited to this, as long as it does not impair the function of the filter 26t. For example, a mesh-like member with coarse mesh can also be used as the stop 26r. In addition, in this embodiment, the filter 26t is basically rectangular in shape. The shape of the filter 26t is not limited to this. For example, the filter 26t can also be formed into a square pyramid shape that matches the shape of the edge 26k10 with an inclined surface.

[0060] In this embodiment, the filter 26t is a filter with a double-layer structure consisting of a high-density portion 26t1 and a low-density portion 26t2. On the other hand, as shown inside, a filter 26t with a single-layer structure can be used. In the single-layer structure, in the standalone state where the filter 26t is not located in the opening 26k1, the weight density per unit volume of the filter 26t gradually increases from the first side (the inside facing the developing apparatus 26) to the second side (the outside facing the developing apparatus 26) in the direction of the arrow in the inside. This formation of the filter 26t causes the weight density per unit volume to gradually increase along the ventilation direction (exhaust direction). Specifically, the filter 26t shown inside has a coarser and looser state on the first side and becomes denser towards the second side. Furthermore, as... Figure 5B As shown, a filter 26t with a multi-layer structure (three or more layers) can be used. In the multi-layer structure, in its standalone state without the filter 26t being positioned in the opening 26k1, the weight density per unit volume of the filter 26t gradually increases from the first side (the inner side facing the developing apparatus 26) to the second side (the outer side facing the developing apparatus 26). In this filter 26t, multiple layers are formed so that the weight density per unit volume gradually increases along the ventilation direction (exhaust direction). Specifically, Figure 5B The filter 26t shown has a coarse and loose state on the first side, and becomes denser and stacked towards the second side.

[0061] First variation

[0062] like Figure 6 As shown, in the developing apparatus 26 of the first modified example, the edges 26k11 and 26k12 of the opening 26k1 have an opening area that gradually increases from the outside of the developing apparatus 26 toward the inside of the developing apparatus 26. Specifically, the opening 26k1 with a two-stage structure includes the opening formed on the outside of the developing apparatus 26 ( Figure 6 The first edge 26k11 with a small opening area (on the upper side) and formed on the inner side of the developing apparatus 26 (on the upper side) Figure 6 The second edge 26k12 (located on the lower side of the filter 26t) has a large opening area. In the first modified example, the high-density portion 26t1 of the filter 26t is fitted into the first edge 26k11. The low-density portion 26t2 abuts against the second edge 26k12, and the high-density portion 26t1... Figure 6 The direction of the black arrow in the image is compressed. Even with this configuration, the defect of air in the developing unit 26 being discharged to the outside of the developing unit 26 along with the toner without passing through the filter 26t can be reduced. As shown in the first modified example, even when the edges 26k11 and 26k12 are formed with a phased reduction in opening area, it is still comparable to... Figure 4ASimilarly, by continuously reducing the opening area of ​​edge 26k10 as shown, the ease of loading and unloading the upper developing cartridge 26k relative to the opening 26k1 is improved. The steps at edges 26k11 and 26k12 prevent the filter 26t from falling off the device.

[0063] Second variation

[0064] like Figure 7 As shown, the developing apparatus 26 of the second modified example (refer to...) Figure 2A The developing unit 26k15 includes a limiting portion 26k15 that prevents the filter 26t from detaching from the opening 26k1 (edge ​​26k10) of the developing unit 26k. Specifically, the limiting portion 26k15 protrudes in the direction of narrowing of the opening and is formed above the opening 26k1 (edge ​​26k10) of the upper developing unit 26k. The limiting portion 26k15 is formed to abut against the second side of the filter 26t (the part with high weight density, i.e., the high-density part 26t1). By providing the limiting portion 26k15 in this way, defects such as the filter 26t disposed in the opening 26k1 detaching from the developing unit 26 can be prevented. In addition, the vertical position of the filter 26t in the opening 26k1 can be easily determined.

[0065] 3rd variation

[0066] like Figure 8 As shown, in the third modified example, the developing apparatus 26 (refer to...) Figure 2A In the opening 26k1, a protrusion 26k20 is formed at the edge 26k10 of the opening 26k1, thereby... Figure 8 The compression filter 26t is located on the second side (the part with high weight density, i.e., the high-density part 26t1) in the direction of the black arrow (the direction intersecting the connecting direction). Specifically, the edge 26k10 (opening 26k1) of the upper developing cartridge 26k is... Figure 4A Unlike the upper developing chamber 26k, it lacks an inclined surface. The edge 26k10 has a protrusion 26k20 (convex portion) above the central portion in the communicating direction, projecting in a direction that narrows the opening. Specifically, the protrusion 26k20 is formed over the entire circumference of the substantially rectangular edge 26k10. Even with this configuration, the high-density portion 26t1 of the filter 26t located in the opening 26k1 is compressed by the protrusion 26k20. This reduces the defect of air in the developing apparatus 26 escaping to the outside of the developing apparatus 26 along with the toner without passing through the filter 26t.

[0067] 4th variation

[0068] like Figure 9 As shown, in the developing apparatus 26 of the fourth modification, the communication direction of the opening 26k1 is not as shown... Figure 4A andFigure 4B The vertical direction shown is not the vertical direction, but rather a basically horizontal direction (in) Figure 9 (In the direction of the white arrow in the image). Specifically, the upper developing cartridge 26k has a portion extending in a substantially vertical direction at a position facing the developing roller 26a. An opening 26k1 is formed in this portion of the upper developing cartridge 26k.

[0069] The opening 26k1 has an edge 26k10 extending in a generally horizontal direction. A filter 26t is disposed (fitted) on the edge 26k10. The filter 26t has a low-density portion 26t2 and a high-density portion 26t1. The low-density portion 26t2 on the first side of the filter 26t is located on the inner side facing the developing apparatus 26. Figure 9 (Right side of the filter 26t). The high-density section 26t1 on the second side of the filter 26t is located on the outside facing the developing device 26. Figure 9 (Left side of the middle). Furthermore, in the fourth variation, the edge 26k10 is also inclined, and the high-density portion 26t1 is compressed in a direction intersecting the communication direction through the edge 26k10. Even with such a configuration, the defect of air in the developing apparatus 26 being discharged to the outside of the developing apparatus 26 along with the toner without passing through the filter 26t can be reduced.

[0070] 5th variation

[0071] like Figure 10 As shown, the developing apparatus 26 of the fifth modified example (refer to...) Figure 9The edge 26k10 of the opening portion 26k1 is formed in a tapered shape, so that the opening area of the opening portion 26k1 continuously decreases from the inside of the developing device 26 to the outside of the developing device 26. Further, in the fifth modification example, the filter 26t is not a two-layer structure of the high-density portion 26t1 and the low-density portion 26t2, but is a single-layer structure in which the weight density per unit volume is substantially uniform. In the case of the edge 26k10 (the opening portion 26k1) configured in this way, not only the two-layer structure, but even if the filter 26t is a one-layer structure, in a state in which the filter 26t is disposed in the opening portion 26k1, the filter 26t is formed so that the weight density per unit volume on the outside of the developing device 26 is greater than the weight density per unit volume on the inside of the developing device 26. That is, in the filter 26t disposed in the opening portion 26k1, the degree of compression on the outside of the developing device 26 is greater than the degree of compression on the inside of the developing device 26. Therefore, the defect that air (the discharge object) leaks together with toner (the collection object) from the lateral side of the filter 26t (between the filter 26t and the opening portion 26k1) in the developing device 26 is reduced. In the present embodiment, since the filter 26t is disposed in close contact with the opening portion 26k1, the defect that air (the discharge object) leaks together with toner (the collection object) from the lateral side of the filter 26t (between the filter 26t and the opening portion 26k1) is further reduced. As a result, the function of the filter 26t is fully executed, and the defect that toner (the collection object) scatters to the outside of the developing device 26 is mitigated. The filter 26t is disposed so that the weight density increases from the upstream side to the downstream side in the ventilation direction (the communication direction), so that the formation of the air flow from the inside to the outside of the developing device 26 is promoted. Therefore, the increase in the internal pressure in the developing device 26 can be effectively suppressed. The overall toner collection properties of the filter 26t can be improved, and the filter 26t is not easily clogged. In addition, in the fifth modification example, the edge 26k10 can also be formed in a stepped manner, so that the opening area of the opening portion 26k1 gradually decreases from the inside of the developing device 26 to the outside of the developing device 26.

[0072] In the embodiment starting from here, the opening portion on the outer side of the developing cartridge is larger than the opening portion on the inner side. According to such a configuration, the following effects can be obtained. At the time of filter replacement maintenance, the filter 26t can be easily replaced without opening the developing cartridge body (the upper developing cartridge 26k and the lower developing cartridge 26j) (even if the upper developing cartridge 26k cannot be attached to or detached from the lower developing cartridge 26j). Even if the developing cartridge body (the upper developing cartridge 26k and the lower developing cartridge 26j) is fixed to each other by adhesion or the like and the upper developing cartridge 26k is not attached to or detached from the developing cartridge 26j, the filter 26t can be easily replaced. When the rectangular filter is compressed, the portion having a low weight density (small repulsive force) is more compressed, and the portion having a high weight density (large repulsive force) can be less compressed. Defects such as bending or variation of the cartridge gap H due to the repulsive force during compression can be reduced. Since the area of the portion having a high weight density and easily clogged can be increased, the product life of the filter 26t can be extended.

[0073] In the developing device 26 related to the present embodiment, the opening portion 26k1 has a rim 26k10 (wall) extending in the communication direction (ventilation direction, which is the vertical direction in Figure 2B and Figure 11A ). The filter 26t provided in the opening portion 26k1 is such that the first side (having a low weight density) is located on the inner side (the lower side in Figure 11A facing the developing device 26, and the second side (having a high weight density) is located on the outer side (the upper side in Figure 11A facing the developing device 26. The filter 26t provided in the opening portion 26k1 abuts against the rim 26k10, and the first side (the side having a low weight density) in the direction intersecting the communication direction (that is, the direction of the black arrow in Figure 11A ) is compressed. Specifically, as shown in Figure 11A , the filter 26t is disposed in the opening portion 26k1 in a state in which the low-density portion 26t2 is compressed in the direction (the intersecting direction) of the black arrow in Figure 11A by the rim 26k10. That is, in Figure 11A , the state in which the filter 26t (the low-density portion 26t2) is compressed and disposed (fitted) in the opening portion 26k1 is shown in two dimensions. However, in reality, the filter 26t (the low-density portion 26t2) is compressed from four sides by abutting against the substantially rectangular rim 26k10.

[0074] More specifically, as shown in Figure 11BAs shown, the length N of the filter 26t in the cross direction intersecting the communicating direction is set to be greater than each of the opening widths M1, M2 (length in the cross direction) of the opening portion 26k1 in the single body state (N > M1 > M2). As shown, the filter 26t is provided in close contact with the opening portion 26k1 in a state compressed according to the shape of the opening portion 26k1. That is, although the high-density portion 26t1 of the filter 26t provided at the opening portion 26k1 is also compressed to some extent, the low-density portion 26t2 of the filter 26t is compressed at a high compression rate. Even in a state where the filter 26t is provided at the opening portion 26k1 in this way, the weight density per unit volume of the high-density portion 26t1 is higher than that of the low-density portion 26t2. Figure 11A As shown, the filter 26t is provided in close contact with the opening portion 26k1 in a state compressed according to the shape of the opening portion 26k1. That is, although the high-density portion 26t1 of the filter 26t provided at the opening portion 26k1 is also compressed to some extent, the low-density portion 26t2 of the filter 26t is compressed at a high compression rate. Even in a state where the filter 26t is provided at the opening portion 26k1 in this way, the weight density per unit volume of the high-density portion 26t1 is higher than that of the low-density portion 26t2.

[0075] As described above, in the developing device 26 of the present embodiment, the weight density per unit volume of the filter 26t on the outside of the developing device 26 is greater than that on the inside of the developing device 26. Defects in which air (discharge object) leaks together with toner (collection object) from the lateral side of the filter 26t (between the filter 26t and the opening portion 26k1) are reduced. In the present embodiment, since the filter 26t is provided in close contact with the opening portion 26k1, defects in which air (discharge object) leaks together with toner (collection object) from the lateral side of the filter 26t (between the filter 26t and the opening portion 26k1) are further reduced. Thus, the function of the filter 26t described above is fully performed, and defects in which toner (collection object) scatters to the outside of the developing device 26 are reduced. In particular, since the filter 26t has a portion with a low weight density per unit volume and is easily compressed, at least the adhesion of the opening portion 26k1 to this portion is ensured. Thus, the above-described effects can be more easily obtained. The filter 26t is formed such that the weight density increases from the upstream side to the downstream side in the communicating direction (air passage direction), and thus the formation of air flow from the inside to the outside of the developing device 26 is facilitated. Thus, the increase in internal pressure in the developing device 26 can be effectively suppressed. The overall toner collection performance of the filter 26t can be improved, and the filter 26t is less likely to be clogged. In a state where the filter 26t is provided at the opening portion 26k1 (actual use state), the portion with a low weight density per unit volume (low-density portion 26t2) is compressed so as to increase the weight density. However, the portion with a low weight density per unit volume (low-density portion 26t2) does not increase as much as the portion with a high weight density per unit volume (high-density portion 26t1).

[0076] In this embodiment, the edge 26k10 of the opening 26k1 is formed such that the opening area of ​​the opening 26k1 extends from the outside to the inside of the developing apparatus 26 (from...). Figure 11A The edge 26k10 decreases continuously from the upper side to the lower side. That is, the edge 26k10 is inclined from the upstream side to the downstream side away from the center of the opening in the exhaust direction (ventilation direction) where air is discharged to the outside of the developing apparatus 26 (an inclined surface is formed in the edge 26k10). This configuration of the edge 26k10 allows the easily compressible low-density portion 26t2 to be compressed at a higher compression ratio. As a result, the adhesion between the filter 26t and the opening 26k1 can be improved. The filter 26t can be easily assembled from the outside of the developing apparatus 26, and the filter 26t can be easily removed from the developing apparatus 26. Furthermore, the inclined lower end of the edge 26k10 serves as a restraint to prevent the filter 26t from falling into the developing apparatus 26.

[0077] In this embodiment, the filter 26t is configured to be detachable from the outside of the developing apparatus 26. In the developing apparatus 26 of this embodiment, the stop 26r is detachably mounted to the outside of the developing apparatus 26. The stop 26r abuts against the filter 26t on the first side (the portion with high weight density, i.e., the high-density portion 26t2) facing the outside of the developing apparatus 26, thereby preventing the filter 26t from falling out of the opening 26k1 (edge ​​26k10) onto the outside of the developing apparatus 26.

[0078] Specifically, when installing a 26t filter, such as Figure 11B As shown, filter 26t in Figure 11B The white arrow moves from above the developing device 26 (opening 26k1) in the direction of the arrow. (Example) Figure 11A As shown, the filter 26t is embedded in the opening 26k1. To prevent the filter 26t from falling upwards, a stop 26r is fixed (screw tightened) to the developing cartridge body (upper developing cartridge 26k and lower developing cartridge 26j) by screws 90 to press the filter 26t from above. In this embodiment, a plate-shaped member with an opening on the inside is used as the stop 26r. The stop 26r is not limited to this, as long as it does not impair the function of the filter 26t. For example, a mesh-like member with coarse mesh can also be used as the stop 26r. In addition, in this embodiment, a filter 26t with a basically cuboid shape is used. The shape of the filter 26t is not limited to this. For example, the filter 26t can also be formed into a square pyramid shape that matches the shape of the edge 26k10 with an inclined surface.

[0079] In this embodiment, the filter 26t is a filter with a double-layer structure consisting of a high-density portion 26t1 and a low-density portion 26t2. On the other hand, as shown inside, a filter with the following structure can be used: in a single-layer structure, when the filter 26t is not located in the opening 26k1, the weight density per unit volume of the filter 26t gradually increases from the first side (the inside facing the developing apparatus 26) to the second side (the outside facing the developing apparatus 26) in the direction of the arrow in the inside. In other words, this filter 26t is formed such that the weight density per unit volume gradually increases along the ventilation direction (exhaust direction). Specifically, the filter 26t shown inside has a coarser and looser state on the first side and becomes denser towards the second side. Such a filter 26t... Figure 5B As shown, for example, it can be manufactured by stacking multiple layers with different weight densities per unit volume.

[0080] 6th variation

[0081] like Figure 12 As shown, in the developing apparatus 26 of the sixth modification, the edges 26k11 and 26k12 of the opening 26k1 have an opening area that gradually decreases from the outside of the developing apparatus 26 toward the inside of the developing apparatus 26. Specifically, the opening 26k1 with a two-stage structure includes a second side formed facing the outside of the developing apparatus 26. Figure 12 The first edge 26k11 with a large opening area (on the upper side) and the first side formed on the inner side facing the developing apparatus 26 (on the upper side) Figure 12 The second edge 26k12 (located on the lower side of the filter 26t) has a small opening area. In the sixth variation, the high-density portion 26t1 of the filter 26t is fitted into the first edge 26k11. The low-density portion 26t2 abuts against the second edge 26k12 and... Figure 12 The direction of the black arrow in the image is compressed. Even with this configuration, the defect of air in the developing unit 26 being discharged to the outside of the developing unit 26 along with the toner without passing through the filter 26t can be reduced. As shown in the first modified example, even when the edges 26k11 and 26k12 are formed with a phased reduction in opening area, it is still comparable to... Figure 11A Similarly, by continuously reducing the opening area of ​​edge 26k10 as shown, the ease of loading and unloading the filter 26t relative to the opening 26k1 is improved. The steps at edges 26k11 and 26k12 prevent the filter 26t from falling into the developing unit 26.

[0082] 7th variation

[0083] like Figure 13As shown, the developing apparatus 26 of the seventh modification has a limiting portion 26k15 that prevents the filter 26t from falling into the developing apparatus 26 from the opening 26k1 (edge ​​26k10). Specifically, a limiting portion 26k15 protruding in the direction of narrowing of the opening is formed below the opening 26k1 (edge ​​26k10) of the developing cartridge body (upper developing cartridge 26k and lower developing cartridge 26j). The limiting portion 26k15 is formed to abut against the first side of the filter 26t (the part with low weight density, i.e., low density part 26t2). This configuration of the limiting portion 26k15 can prevent the filter 26t provided in the opening 26k1 from falling into the inside of the developing apparatus 26. In addition, the vertical position of the filter 26t in the opening 26k1 can be easily determined.

[0084] 8th variation

[0085] like Figure 14 As shown, in the developing apparatus 26 of the eighth modification, the stop member 26r (filter cover) is detachably mounted to the outside of the developing apparatus 26. The stop member 26r abuts against the first side of the filter 26t (the part with high weight density, i.e., the high-density part 26t1), preventing the filter 26t from falling off the opening 26k1 (edge ​​26k10) to the outside of the developing apparatus 26. The stop member 26r in the eighth modification has multiple protrusions 26r1 (ribs) that can abut against the filter 26t (high-density part 26t1) from the outside of the developing apparatus 26. Specifically, the protrusions 26r1 are formed by protruding downward from a plate-shaped part that is not annular and does not have through holes. In order to press the filter 26t, which is basically cuboid in shape, in a balanced manner, at least four protrusions 26r1 are provided at intervals in the longitudinal and transverse directions. The stop 26r is formed such that the portion other than the plurality of protrusions 26r1 faces the filter 26t with a gap. Air that has passed through the filter 26t from the inside of the developing unit 26 is discharged to the outside of the developing unit 26 through the gap between the stop 26r and the filter 26t. In this way, by pressing the center of the filter 26t with the stop 26r provided with the plurality of protrusions 26r1, the defect of the center of the filter 26t floating due to the air discharged from the developing unit 26t can be reduced. Preferably, only a portion of the outer edge of the plate-shaped portion of the stop 26r (e.g., the four corners) is attached to the developing unit 26 by means of a clip or the like, so as not to interfere with the exhaust from the gap.

[0086] 9th variation

[0087] like Figure 15AAs shown, the filter 26t provided in the developing device 26 of the ninth modified example is also formed in a basic rectangular parallelepiped shape in a single body state. Specifically, in the single body state, the filter 26t has a rectangular shape and has a thickness Z1 (thickness in the communication direction), a length D in the long side direction (long side direction orthogonal to the communication direction), and a length N in the lateral direction (orthogonal in the communication direction). In the ninth modified example, in the state where the filter 26t is provided in the opening 26k1 (developing device 26), the thickness in the long side direction orthogonal to the communication direction is smaller at both ends in the long side direction than the thickness at the central portion in the long side direction. That is, as Figure 15B shown, when observing the filter 26t disposed in the opening 26k1 from the length direction (direction perpendicular to the paper surface equivalent to Figure 2B ), the thickness Z2 at both ends in the long side direction of the filter 26t is thinner than the thickness Z1 at the central portion in the long side direction (Z1>Z2). Specifically, in the developing device 26 of the ninth modified example, the opening 26k1 has a two-stage structure. When observing in the long side direction, the first edge 26k11 having a large opening width D' (which is equal to or slightly smaller than the direction length D of the filter 26t) is formed on the second side ( Figure 15B upper side) facing the outside of the developing device 26. The second edge 26k12 having a small opening width is formed on the first side facing the inside of the developing device 26 ( Figure 15B lower side). The depth Z2 (length in the communication direction) of the first edge 26k11 is set to be smaller than the thickness Z1 of the filter 26t (Z2<Z1). The filter 26t provided in the two-stage opening 26k1 is in a state where both ends in the long side direction are pressed by the stepped portions in the vertical and horizontal directions. Even when the dimensional tolerance of the length D in the long side direction of the filter 26t is large, both ends in the long side direction are firmly pressed by the above-mentioned steps of the opening 26k1 and are in close contact with the opening 26k1. Therefore, it is possible to reduce the defect that air and toner in the developing device 26 are discharged to the outside of the device together from between the opening 26k1 and the filter 26t. That is, in the ninth modified example, when observing the filter 26t disposed in the opening 26k1 from the lateral direction (direction equivalent to Figure 2B the left-right direction), as Figure 11A shown, the filter 26t is arranged in the opening 26k1 (edge formed in a conical shape) in such a way that the lower part is compressed to a size M2 (<M1≤N) in the lateral direction. Thus, only both end portions in the long side direction of the filter 26t are pressed in the vertical direction (thickness direction), and both end portions in the lateral direction are not pressed in the vertical direction (thickness direction). This is because if the filter 26t in the lateral direction is pressed in the vertical direction, the compression degree of the low-density portion 26t2 may be too large and the filtering function may be reduced.

[0088] As described above, the developing device 26 in the present embodiment is a filter holding device in which the filter 26t is disposed in the opening portion 26k1 that communicates the inside and the outside of the developing device 26. The opening portion 26k1 has a rim 26k10 that extends in a communicating direction from the inside of the developing device 26 to the outside of the developing device 26. The filter 26t is formed in a manner in which the weight density per unit volume of a first side of the filter 26t is lower than the weight density per unit volume of a second side of the filter 26t in a single body state in which the filter 26t is not disposed in the opening portion 26k1. The filter 26t is disposed in the opening portion 26k1 so that the first side is located toward the inside of the developing device 26 and the second side is located toward the outside of the developing device 26. At least a portion of the filter 26t is compressed in a direction that intersects the communicating direction by abutting against the rim 26k10. Specifically, in a state in which the filter 26t is disposed in the opening portion 26k1, the weight density per unit volume of the filter 26t at the second side that faces the outside of the developing device 26 is greater than the weight density per unit volume of the filter 26t at the first side that faces the inside of the developing device 26. Therefore, it is possible to reduce a defect in which air (an exhaust target) in the developing device 26 is exhausted to the outside of the developing device 26 together with toner (a collection target).

[0089] In the present embodiment, the process cartridge 20 does not include the developing device 26, and the developing device 26 is a unit that can be attached to and detached from the main body of the image forming apparatus 1 independently. Alternatively, the developing device 26 can be one of the constituent components of the process cartridge 20, and the process cartridge 20 can be configured to be attached to and detached from the main body of the image forming apparatus 1 as a unit. In such a configuration, the same effects as those of the above-described embodiments and modified examples can be obtained. It should be noted that the term "process cartridge" used in the present disclosure refers to a movable unit that includes at least one of a charging device for charging an image bearing member, a developing device for developing a latent image on the image bearing member, and a cleaning device for cleaning the image bearing member, and is designed to be attached to and detached from the main body of the image forming apparatus as a unitized component.

[0090] In the present embodiment, the present disclosure is applied to the developing device 26 in which two conveying screws 26b1 and 26b2 serving as conveying members are arranged horizontally in parallel and the doctor blade 26c is provided below the developing roller 26a. The configuration of the developing device to which the present disclosure is applied is not limited to the above-described configuration. The present disclosure is applicable to other developing devices, for example, a developing device in which three or more conveying members are arranged in parallel in the horizontal direction, a developing device in which a plurality of conveying members are arranged in parallel in the vertical direction, and a developing device in which a doctor blade is provided above a developing roller. In the present embodiment, the present disclosure is applied to the developing device 26 that accommodates a two-component developer including toner and a carrier. Alternatively, the present disclosure is also applicable to a developing device that accommodates a one-component developer (i.e., toner that can include an additive). This case also achieves substantially the same effects as the above-described effects.

[0091] In the present embodiment, the present disclosure is applied to the developing device 26 as a filter holding device, but the filter holding device to which the present disclosure is applied is not limited thereto. The present disclosure is applicable to any type of device that accommodates powder such as toner on the inside, for example, the toner container 70, the waste toner container 80, the cleaning device 23, the intermediate transfer belt cleaning device 81, the toner replenishment device, and the toner conveying device. Further, in the present embodiment, the present disclosure is applied to the developing device 26 as a filter holding device that is configured to discharge air that is a discharge target to the outside of the developing device 26. The filter holding device to which the present disclosure is applied (combination of the discharge target and the collection target) is not limited thereto. For example, the present disclosure can be applied to the main body of the image forming apparatus 1 as a filter holding device that is configured to collect ozone that is a collection target and discharge air (air that does not contain ozone) that is a discharge target to the outside of the image forming apparatus 1. In addition, in the present embodiment, the high-density portion 26t1 of the filter 26t is configured to be largely compressed in a direction intersecting the communication direction by the inclined surface of the rim 26k10. The entire side surface (non-ventilation surface) of the filter 26t can also be configured to be compressed in the direction intersecting the communication direction by the rim 26k10. The portion other than the high-density portion 26t1 can also be configured to be compressed in the direction intersecting the communication direction by the rim 26k10. Such a configuration can also be employed as long as the adhesion (sealing property) between the side surface of the filter 26t and the rim 26k10 can be ensured. This case also achieves substantially the same effects as the above-described effects.

[0092] This embodiment is illustrative and is not restrictive of the present disclosure. Thus, many additional modifications and variations are possible in light of the above teachings. For example, elements and / or features of different illustrative embodiments can be combined with each other and / or substituted for each other within the scope of the present disclosure. Thus, it is to be understood that the present disclosure can be practiced otherwise than specifically described herein without departing from its scope. In addition, the number, position and / or shape of the constituent components are not limited to those of the present embodiment, and can be any number, position and / or shape suitable for implementing the present disclosure.

[0093] This application is based on and claims priority to Japanese Patent Application No. 2020-169669, filed on October 7, 2020, in the Japan Patent Office, Japanese Patent Application No. 2020-169685, filed on October 7, 2020, in the Japan Patent Office, and Japanese Patent Application No. 2021-051281, filed on March 25, 2021, in the Japan Patent Office, the entire disclosures of which are incorporated herein by reference.

[0094] List of Reference Numerals

[0095] 1 Image forming apparatus

[0096] 20, 20Y, 20M, 20C, 20BK Process cartridge

[0097] 21 Photoreceptor drum (image bearer)

[0098] 26 Developing device (filter holding device)

[0099] 26a Developing roller (developer bearer)

[0100] 26j Lower side developing cartridge

[0101] 26k Upper side developing cartridge

[0102] 26k1 Opening (air passage path)

[0103] 26k10 Edge (wall)

[0104] 26k11, 26k12 Edge

[0105] 26k15 Restriction portion

[0106] 26k20 Protruding portion (convex portion)

[0107] 26t Filter

[0108] 26t1 High-density portion

[0109] 26t2 Low-density portion

[0110] 26r Stopper

Claims

1. A developing device characterized by comprising includes: an opening portion configured to communicate an inside of the developing device with an outside of the developing device, the opening portion having a rim extending in a communication direction from the inside of the developing device toward the outside of the developing device, and a filter provided in the opening portion, the filter includes: a first side facing the inside of the developing device, and a second side facing the outside of the developing device, in a state where the filter is provided in the opening portion, the filter has a weight density per unit volume that is greater on the second side than on the first side, in the state where the filter is provided in the opening portion such that the first side of the filter faces the inside of the developing device and the second side of the filter faces the outside of the developing device, the filter is compressed on the first side in a cross direction that intersects the communication direction by abutting against the rim.

2. The developing device according to claim 1, wherein: in a single state where the filter is not provided in the opening portion, the filter has a weight density per unit volume that is less on the first side than on the second side.

3. The developing device according to claim 2, wherein: the filter has a two-layer configuration, wherein, in the single state where the filter is not provided in the opening portion, a low-density portion is provided on the first side and a high-density portion is provided on the second side, the low-density portion having a weight density per unit volume that is lower than the high-density portion, the filter is provided in the opening portion in a state where the low-density portion is compressed in the cross direction by the rim.

4. The developing device according to claim 1, wherein: the rim has a shape such that an opening area of the opening portion continuously or stepwise decreases from the inside of the developing device toward the outside of the developing device.

5. The developing device according to claim 4, wherein: the filter has a single-layer configuration in which a weight density per unit volume is substantially the same.

6. The developing device according to any one of claims 1 to 5, wherein: in the state where the filter is provided in the opening portion, a thickness of the filter at both ends in a long-side direction orthogonal to the communication direction is thinner than a thickness of the filter at a central portion in the long-side direction.

7. The developing device according to any one of claims 1 to 6, further comprising: a restriction portion configured to restrict the filter from falling from the opening portion to the inside of the developing device.

8. The developing device according to claim 7, wherein: the restriction portion abuts against the first side of the filter.

9. The developing device according to any one of claims 1 to 8, further comprising: a detachable stopper configured to abut against the filter to prevent the filter from falling from the opening portion to the outside of the developing device.

10. The developing device according to claim 9, wherein: The stopper has a plurality of protrusions that abut against the filter from the outside of the developing device, A portion of the stopper other than the plurality of protrusions faces the filter with a gap.

11. A developing device characterized by comprising Comprises: An opening portion configured to communicate an inside of the developing device with an outside of the developing device, the opening portion including a rim that extends in a communication direction from the inside of the developing device toward the outside of the developing device, and A filter disposed in the opening portion, The filter comprises: a first side facing the inside of the developing device, and a second side facing the outside of the developing device, wherein, in a single state in which the filter is not disposed in the opening portion, the filter has a weight density per unit volume that is smaller on the first side than on the second side, in a state in which the filter is disposed in the opening portion such that the first side of the filter faces the inside of the developing device and the second side of the filter faces the outside of the developing device, at least a portion of the filter is compressed in a cross direction that intersects the communication direction by abutting against the rim.

12. The developing apparatus according to claim 11, characterized in that : The filter is disposed in the opening portion in a state in which the filter is compressed on the second side in the cross direction by the rim.

13. The developing device according to claim 11 or 12, wherein: the filter has a two-layer configuration, wherein, in a single state in which the filter is not disposed in the opening portion, a low-density portion is provided on the first side and a high-density portion is provided on the second side, the low-density portion having a weight density per unit volume that is lower than that of the high-density portion, the filter is disposed in the opening portion in a state in which the high-density portion is compressed in the cross direction by the rim.

14. The developing device according to any one of claims 11 to 13, wherein: the rim has a shape such that an opening area of the opening portion continuously or stepwise increases from the outside of the developing device toward the inside of the developing device.

15. The developing device according to any one of claims 11 to 14, further comprising: a restriction portion configured to restrict the filter from falling out of the opening portion to the outside of the developing device.

16. The developing device according to any one of claims 11 to 15, wherein : the rim has a protruding portion that protrudes in a direction that intersects the communication direction and compresses the filter on the second side.

17. The developing device according to any one of claims 11 to 16, wherein: the communication direction of the opening portion is substantially horizontal.

18. The developing device according to any one of claims 11 to 17, further comprising: a detachable stopper to prevent the filter from falling out of the opening portion to the inside of the developing device.

19. A process cartridge, comprising: a main body configured to be detachably attached to an image forming apparatus, the process cartridge comprising: an image bearing body, and a filter disposed in an opening portion of the main body. The developing device of any one of claims 1 to 18 configured to accommodate toner on an inner side to develop a latent image formed on a surface of the image bearer.

20. An image forming apparatus, characterized by Comprising: The developing device of any one of claims 1 to 18, and The process cartridge of claim 19.

21. A developing device characterized by comprising Comprising: An opening portion configured to communicate an inner side of the developing device with an outer side of the developing device, the opening portion having a rim extending in a communication direction from the inner side of the developing device toward the outer side of the developing device, and A filter provided in the opening portion, The filter comprising: A first side facing the inner side of the developing device, and A second side facing the outer side of the developing device, In a state where the filter is provided in the opening portion, the filter has a weight density per unit volume greater at the second side than at the first side, The rim has a shape such that an opening area of the opening portion continuously or stepwise decreases from the outer side of the developing device toward the inner side of the developing device, In the state where the filter is provided in the opening portion such that the first side of the filter faces the inner side of the developing device and the second side of the filter faces the outer side of the developing device, the filter is compressed at the first side in a cross direction intersecting the communication direction by abutting against the rim.

22. The developing device of claim 21, wherein: In the state where the filter is provided in the opening portion, a thickness of the filter at both ends in a long side direction orthogonal to the communication direction is thinner than a thickness of the filter at a central portion in the long side direction.

23. The developing device of claim 21 or 22, wherein: Further comprising a restriction portion configured to restrict the filter from falling from the opening portion to the inner side of the developing device.

24. The developing device of claim 23, wherein: The restriction portion abuts against the first side of the filter.

25. The developing device of any one of claims 21 to 24, wherein: Further comprising a removable stopper configured to abut against the filter to prevent the filter from falling from the opening portion to the outer side of the developing device.

26. The developing device of claim 25, wherein: The stopper has a plurality of protrusions that abut against the filter from the outer side of the developing device, A portion of the stopper other than the plurality of protrusions faces the filter with a gap.

27. A process cartridge, comprising: A main body configured to be removably attached to an image forming apparatus, The process cartridge comprising: An image bearer, and The developing device of any one of claims 21 to 26 configured to accommodate toner on an inner side to develop a latent image formed on a surface of the image bearer.

28. An image forming apparatus, characterized by Comprising: The developing device of any one of claims 21 to 26, and The process cartridge of claim 27.

Images