FILTER HOLDING DEVICE, DEVELOPING DEVICE, PROCESS CARTRIDGE, IMAGE FORMING APPARATUS, AND FILTER

Abstract

To reduce a trouble that an exhaust object in a device is exhausted to the outside of the device together with a collection object.SOLUTION: A developing device 26 (filter holding device) is installed with a filter 26t in an opening 26k1 that communicates the inside of the device and the outside of the device, and the filter 26t is formed such that the weight density per unit volume on one end becomes lower than the weight density per unit volume on the other end. The filter 26t is installed in the opening 26k1 so that one end is located on the inside of the device and the other end is located on the outside of the device. The filter 26t is covered by a non-air-permeable member 26u with no air permeability on at least one end (with lower weight density).SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a filter holding device having a filter installed in an opening, a developing device containing toner, a process cartridge, an image forming device including at least one of them, and the filter. [Background technology]

[0002] Conventionally, in developing devices installed in image forming devices such as copiers and printers, a technique has been known in which a filter is installed in an opening formed in the upper part of a developing case in order to prevent toner from scattering due to an increase in internal pressure within the device (see, for example, Patent Document 1).

[0003] More specifically, in the developing device of Patent Document 1, even if the internal pressure of the device is about to rise, the air inside the device is discharged to the outside of the device through an opening where a filter is installed, so the internal pressure rise is suppressed. And even if the toner floating inside the device is about to be discharged to the outside of the device together with the air when the air inside the device is discharged to the outside of the device in this way, the toner is captured by the filter, so the toner is prevented from scattering outside the device. Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional technology, there was a possibility that toner (object to be collected) would leak out from the side of the filter together with the air (object to be discharged) inside the device. In such a case, the filter would not function properly and the toner (object to be collected) would scatter outside the device.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a filter holding device, a developing device, a process cartridge, an image forming device, and a filter that reduce the problem of objects to be discharged from within the device being discharged outside the device together with objects to be collected. [Means for solving the problem]

[0006] The filter holding device of the present invention is a filter holding device in which a filter is installed in an opening that communicates between the inside of the device and the outside of the device, and the filter is a two-layer structure in which a low-density part with a low weight density per unit volume is formed on one end side and a high-density part with a high weight density per unit volume is formed on the other end side, and the filter is installed in the opening so that the one end side is located on the inside of the device and the other end side is located on the outside of the device, and the side of the low-density part is covered with a non-air-permeable member that does not have air permeability, and the non-air-permeable member is placed in the opening so as to be sandwiched between the opening and the side of the low-density part. Installation and the side surface of the high density portion is in contact with the opening. The contact is made without the air-impermeable member being interposed therebetween. It is something. Effect of the Invention

[0007] According to the present invention, it is possible to provide a filter holding device, a developing device, a process cartridge, an image forming apparatus, and a filter that reduce the problem of objects to be discharged from within the apparatus being discharged outside the apparatus together with objects to be collected. [Brief description of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. [Diagram 3] FIG. 2 is a diagram showing the developing device in the longitudinal direction. [Figure 4] 1A is an enlarged cross-sectional view showing a state in which a filter is installed in the opening of the developing device, and FIG. 1B is an enlarged cross-sectional view showing a state before the filter is installed in the opening of the developing device. [Diagram 5] 1A and 1B are a cross-sectional side view and a bottom view, respectively, showing a filter according to another embodiment. [Figure 6] FIG. 11 is an enlarged view showing a state in which a filter is installed at an opening of a developing device according to a first modified example. [Figure 7]FIG. 11 is an enlarged view showing a state in which a filter is installed at an opening of a developing device according to a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and the duplicated description will be appropriately simplified or omitted.

[0010] First, the overall configuration and operation of an image forming apparatus 1 will be described with reference to FIG. The image forming apparatus 1 in this embodiment is a tandem type color image forming apparatus in which a plurality of process cartridges 20Y, 20M, 20C, and 20BK are arranged side by side so as to face an intermediate transfer belt 40. In addition, a developing device 26 (see FIG. 2) serving as a filter holding device (device with a filter) is provided so as to face the photosensitive drums 21 of the plurality of process cartridges 20Y, 20M, 20C, and 20BK.

[0011] In FIG. 1, reference numeral 1 denotes the main body of a color copier as an image forming device, 2 denotes an original transport section which transports an original to an original reading section 3, 3 denotes an original reading section which reads image information of the original, and 4 denotes a writing section (exposure section) which emits laser light based on input image information. Also, 20Y, 20M, 20C, and 20BK denote process cartridges corresponding to the respective colors (yellow, magenta, cyan, and black), and 40 denotes an intermediate transfer belt onto which toner images of a plurality of colors are transferred in an overlapping manner. Also, 61 denotes a paper feeding device in which sheets P such as paper are stored, 65 denotes a secondary transfer roller that transfers the toner image formed on the intermediate transfer belt 40 onto the sheet P, and 66 denotes a fixing device that fixes an unfixed image on the sheet P. In addition, reference numeral 70 denotes a toner container for replenishing toner of each color to each developing device 26 corresponding to the multiple process cartridges 20Y, 20M, 20C, and 20BK, and reference numeral 80 denotes a waste toner collection container in which untransferred toner collected by the cleaning device 23 (see FIG. 2) or the intermediate transfer belt cleaning device 81 is collected as waste toner.

[0012] 2, each of the process cartridges 20Y, 20M, 20C, and 20BK is an integral unit of a photosensitive drum 21 as an image carrier, a charging device 22, and a cleaning device 23. When each of the process cartridges 20Y, 20M, 20C, and 20BK reaches the end of its life, it is removed from the image forming apparatus main body 1 and replaced with a new one. Each developing device 26 is disposed so as to face the photosensitive drum 21 of each process cartridge 20Y, 20M, 20C, 20BK. When the developing device 26 reaches the end of its life, it is removed from the image forming apparatus main body 1 and replaced with a new one. The operation of attaching and detaching the developing device 26 to and from the image forming apparatus main body 1 and the operation of attaching and detaching the process cartridges 20Y, 20M, 20C, 20BK to and from the image forming apparatus main body 1 can be performed separately and independently. A toner image of each color (yellow, magenta, cyan, black) is formed on the photosensitive drum 21 (image carrier) of each of the process cartridges 20Y, 20M, 20C, and 20BK.

[0013] Hereinafter, the operation of the image forming apparatus during normal color image formation will be described. First, the document is transported from the document table by the transport rollers of the document transport unit 2 and placed on the contact glass of the document reading unit 3. Then, the document reading unit 3 optically reads image information of the document placed on the contact glass. Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 4. Then, from the writing unit 4, laser light L (exposure light) based on the image information of each color is irradiated toward the surface of the photosensitive drum 21 (see FIG. 2) of the corresponding process cartridge 20Y, 20M, 20C, and 20BK.

[0014] Meanwhile, each of the four photoconductor drums 21 rotates in a clockwise direction in Fig. 1 and Fig. 2. First, the surface of the photoconductor drum 21 is uniformly charged at a position facing the charging device 22 (charging roller) (charging process). In this way, a charging potential is formed on the photoconductor drum 21. Thereafter, the charged surface of the photoconductor drum 21 reaches a position irradiated with laser light by each writing unit 4, and an electrostatic latent image based on image information is formed at that position (exposure process).

[0015] The laser light corresponding to the yellow component is irradiated onto the surface of the photoconductor drum 21 of the first process cartridge 20Y from the left side of the drawing. At this time, the laser light of the yellow component is scanned in the direction of the rotation axis (main scanning direction) of the photoconductor drum 21 by a polygon mirror rotating at high speed. In this way, an electrostatic latent image corresponding to the yellow component is formed on the photoconductor drum 21 after it has been charged by the charging device 22. Similarly, the cyan laser light is irradiated onto the surface of the photoconductor drum 21 of the second process cartridge 20C from the left on the paper, forming an electrostatic latent image of the cyan component. The magenta laser light is irradiated onto the surface of the photoconductor drum 21 of the third process cartridge 20M from the left on the paper, forming an electrostatic latent image of the magenta component. The black laser light is irradiated onto the surface of the photoconductor drum 21 of the fourth process cartridge 20BK from the left on the paper, forming an electrostatic latent image of the black component.

[0016] Thereafter, the surface of the photoconductor drum 21 on which the electrostatic latent images of each color are formed reaches a position facing the developing device 26. Then, toner of each color is supplied from each developing device 26 onto the photoconductor drum 21, and the latent images on the photoconductor drum 21 are developed (this is the developing process). Thereafter, the surfaces of the photoconductor drums 21 after the developing process reach positions facing the intermediate transfer belt 40. Here, primary transfer rollers 24 are provided at each of the facing positions so as to abut against the inner circumferential surface of the intermediate transfer belt 40. Then, at the positions of the primary transfer rollers 24, the toner images of each color formed on the photoconductor drums 21 are transferred onto the intermediate transfer belt 40 in order, superimposed on top of each other (this is the primary transfer process).

[0017] Then, the surfaces of the photoconductor drums 21 after the primary transfer process reach a position facing the cleaning device 23. Then, the cleaning device 23 collects the untransferred toner remaining on the photoconductor drums 21 (cleaning process). The untransferred toner collected by the cleaning device 23 passes through a waste toner transport path (not shown) and is collected in the waste toner collection container 80. Thereafter, the residual potential on the surface of the photosensitive drum 21 is removed at the position of the charge removing device, and a series of image forming processes on the photosensitive drum 21 is completed.

[0018] On the other hand, the surface of the intermediate transfer belt 40 onto which the images of each color on the photoconductor drum 21 are transferred and superimposed runs in the direction of the arrow in the figure and reaches the position of the secondary transfer roller 65. Then, at the position of the secondary transfer roller 65, the full-color image on the intermediate transfer belt 40 is secondarily transferred onto the sheet P (secondary transfer process). Thereafter, the surface of the intermediate transfer belt 40 reaches the position of the intermediate transfer belt cleaning device 81. Then, the untransferred toner on the intermediate transfer belt 40 is collected by the intermediate transfer belt cleaning device 81, and a series of transfer processes on the intermediate transfer belt 40 is completed. The untransferred toner collected by the intermediate transfer belt cleaning device 81 passes through a waste toner transport path (not shown) and is collected in a waste toner collection container 80.

[0019] Here, the sheet P conveyed to the position of the secondary transfer roller 65 is conveyed from the paper feeder 61 via the registration roller 64 and the like. Specifically, the sheet P fed by a feed roller 62 from a sheet feeder 61 that stores the sheet P passes through a conveying path and is then guided to the position of a registration roller 64. The sheet P that has reached the position of the registration roller 64 is conveyed toward the position of a secondary transfer roller 65 in synchronization with the toner image on the intermediate transfer belt 40.

[0020] Thereafter, the sheet P onto which the full-color image has been transferred is guided to the position of the fixing device 20. Then, in the fixing device 20, the color image is fixed onto the sheet P at the nip between a fixing roller and a pressure roller. After the fixing process, the sheet P is discharged as an output image outside the apparatus main body 1 by a discharge roller 69, and is then stacked on the discharge tray 5, completing a series of image forming processes.

[0021] Next, the image forming unit of the image forming apparatus will be described in detail with reference to FIG. 2 and FIG. In addition, the four image-forming units installed in the image forming apparatus main body 1 have almost the same structure except for the color of toner used in the image-forming process, so they are illustrated without the alphabetical symbols (Y, M, C, BK) for components such as process cartridges and developing devices.

[0022] As shown in FIG. 2, the process cartridge 20 mainly includes a photosensitive drum 21 as an image carrier, a charging device 22, and a cleaning device 23 housed integrally in a case. The photoconductor drum 21 is a negatively charged organic photoconductor, and is configured by providing a photosensitive layer and the like on a drum-shaped conductive support. The charging device 22 is a charging roller in which a medium-resistance elastic layer is coated on the outer periphery of a conductive core metal. A predetermined voltage is applied from a power supply unit to the charging device 22 (charging roller), thereby uniformly charging the surface of the opposing photoconductor drum 21. The cleaning device 23 is provided with a cleaning blade 25a and a cleaning roller 25b that come into contact with the photoreceptor drum 21. The cleaning blade 25a is made of a rubber material such as urethane rubber, and comes into contact with the surface of the photoreceptor drum 21 at a predetermined angle and with a predetermined pressure. The cleaning roller 25b is a brush roller with brush bristles arranged around a core metal.

[0023] As shown in Figures 2 and 3, the developing device 26 is mainly composed of a developing roller 26a as a developer carrier, a first transport screw 26b1 (first transport member) facing the developing roller 26a, a second transport screw 26b2 (second transport member) facing the first transport screw 26b1 via a partition member 26e, and a doctor blade 26c (developer regulating member) facing the developing roller 26a and regulating the amount of developer carried on the developing roller 26a. Incidentally, the developing device 26 in this embodiment also functions as a filter holding device that holds the filter 26t (toner filter), which will be described in detail later.

[0024] The developing device 26 contains a developer (two-component developer) made up of a carrier and a toner. The developing roller 26a is configured to form a developing area by facing the photosensitive drum 21 with a small gap therebetween. As shown in Fig. 3, the developing roller 26a is configured with a magnet 26a1 that is fixed inside and forms multiple poles (magnetic poles) on the outer circumferential surface of the roller, and a sleeve 26a2 that rotates around the magnet 26a1.

[0025] The transport screws 26b1 and 26b2 as transport members transport the developer contained inside the developing device 26 in the longitudinal direction to form a circulation path (a circulation path indicated by a dashed arrow in FIG. 3). That is, a circulation path for the developer is formed by a first transport path B1 formed by the first transport screw 26b1 and a second transport path B2 formed by the second transport screw 26b2. The first transport path B1 and the second transport path B2 are separated by a partition member 26e (wall portion), and both ends of the two transport paths B1 and B2 in the longitudinal direction communicate with each other via communication openings 26f and 26g. Specifically, referring to FIG. 3, the upstream end of the first transport path B1 in the transport direction communicates with the downstream end of the second transport path B2 in the transport direction via the first communication opening 26f. Also, the downstream end of the first transport path B1 in the transport direction communicates with the upstream end of the second transport path B2 in the transport direction via the second communication opening 26g. That is, the partition member 26e is disposed at a position excluding both ends in the longitudinal direction. The first transport screw 26b1 (first transport path B1) is disposed so as to face the developing roller 26a, and the second transport screw 26b2 (second transport path B2) is disposed so as to face the first transport screw 26b1 (first transport path B1) via a partition member 26e. The first transport screw 26b1 transports the developer in the longitudinal direction while supplying the developer toward the developing roller 26a and recovering the developer after the developing process that has been separated from the developing roller 26a. The second transport screw 26b2 stirs and mixes the developer after the developing process transported from the first transport path B1 and fresh toner supplied from the supply port 26d while transporting them in the longitudinal direction. In this embodiment, the two conveying screws 26b1 and 26b2 are arranged side by side in the horizontal direction. Each of the two conveying screws 26b1 and 26b2 has a screw portion wound around a rotating shaft.

[0026] The above-mentioned image forming process will now be described in more detail, focusing on the development process. The developing roller 26a rotates in the direction of the arrow in Fig. 2. As shown in Fig. 3, the developer in the developing device 26 circulates in the longitudinal direction while being stirred and mixed with the toner supplied from the toner container 70 through the toner supply port 26d via the toner supply path by the rotation in the direction of the arrow of the first transport screw 26b1 and the second transport screw 26b2, which are arranged with a partition member 26e interposed therebetween (circulation in the direction of the dashed arrow in Fig. 3). The toner that is frictionally charged and attracted to the carrier is lifted up onto the developing roller 26a together with the carrier by the developer lifting pole formed on the developing roller 26a. The developer carried on the developing roller 26a is transported in the direction of the arrow in FIG. 2 to reach a position facing the doctor blade 26c. The developer on the developing roller 26a is then transported to a position facing the photoconductor drum 21 (the developing area) after the amount of developer on the developing roller 26a is adjusted to an appropriate amount at this position. The toner is then attracted to the latent image formed on the photoconductor drum 21 by the electric field formed in the developing area. After that, the developer remaining on the developing roller 26a reaches above the first transport path B1 as the sleeve rotates, and is released from the developing roller 26a at this position. Here, the electric field in the developing area is formed by a predetermined voltage (developing bias) applied to the developing roller 26a by the power source for development, and a surface potential (latent image potential) formed on the surface of the photoconductor drum 21 by the charging process and the exposure process.

[0027] The toner in the toner container 70 is appropriately replenished into the developing device 26 from the replenishing port 26d via a toner replenishing path (not shown) as the toner in the developing device 26 is consumed. The consumption of the toner in the developing device 26 is detected by a toner concentration sensor (not shown) that magnetically detects the toner concentration of the developer in the developing device 26 (the ratio of toner in the developer). The supply port 26d is provided at one end of the second conveying screw 26b2 in the longitudinal direction (the left-right direction in FIG. 3) and above the second conveying screw 26b2 (second conveying path B2).

[0028] The configuration and operation of the developing device 26 serving as a filter holding device, which is a characteristic feature of this embodiment, will now be described in detail. 2, 4(A), etc., the developing device 26 in this embodiment also functions as a filter holding device in which a filter 26t is installed in an opening 26k1 that connects the inside of the device to the outside of the device. In FIG. 4, the upper side of the developing case 26k is the outside of the device (the outside of the developing device 26), and the lower side is the inside of the device (the inside of the developing device 26). More specifically, an opening 26k1 (ventilation path) penetrating from inside to outside is formed in the ceiling of the development case 26k (housing) of the development device 26. A filter 26t is provided to close the opening 26k1. The filter 26t is for collecting toner as powder and for allowing air to pass through. In other words, an opening 26k (air passage) for sending air from the inside of the developing device 26 to the outside is formed in the developing case 26k. The filter 26t is installed at the opening 26k. The filter 26t is made of a mesh smaller than the particle size of the toner T and carrier C, and is formed so that only air can pass through. In this embodiment, the opening 26k1 opens in an approximately rectangular shape, and the filter 26t (in its stand-alone state) is formed in an approximately rectangular parallelepiped shape, but the shapes of the opening 26k1 and the filter 26t are not limited to those in this embodiment.

[0029] Here, the gap H (casing gap) between the developing roller 26a and the developing case 26k on the downstream side of the developing area is set to be within the range of 0.6 to 1.0 mm. If the casing gap H becomes smaller than 0.6 mm, the developer carried by the developing roller 26a after the development process is not smoothly transported to the gap H between the developing roller 26a and the developing case 26k, and is likely to overflow and leak out of the developing device 26. On the other hand, if the casing gap H is larger than 1.0 mm, the developer carried by the developing roller 26a will have difficulty sliding against the inner surface of the developing case 26k, making it difficult for the pump action to form an intake airflow toward the inside of the developing device 26, and toner scattering from the developing device 26 (toner scattering around the development area) will be more likely to occur. By maintaining the casing gap H within an appropriate range, leakage of developer and scattering of toner can be reduced. Furthermore, the internal pressure of the developing device 26 tends to increase due to the suction airflow in the casing gap H described above, and if the internal pressure increases, toner will scatter from the gaps in the developing device 26. In contrast, in this embodiment, the opening 26k1 in which the filter 26t is installed is provided, so that the toner is collected and prevented from scattering to the outside while only allowing ventilation, thereby suppressing an increase in the internal pressure of the developing device 26. In other words, toner scattering due to an increase in the internal pressure of the developing device 26 is prevented.

[0030] Here, in this embodiment, filter 26t is formed so that the weight density per unit volume at one end side (lower in Figure 4) is lower than the weight density per unit volume at the other end side (upper in Figure 4). That is, the weight density per unit volume of filter 26t is not uniform, but rather there are low and high weight density portions in the ventilation direction (communication direction). In other words, filter 26t has a gradient in weight density per unit volume.

[0031] More specifically, in this embodiment, the filter 26t is a two-layer structure in which a low-density portion 26t2 having a low weight density per unit volume is formed on one end side, and a high-density portion 26t1 having a high weight density per unit volume is formed on the other end side. That is, in the filter 26t, the low-density portion 26t2 on one end side is coarse and relatively fluffy, while the high-density portion 26t1 on the other end side is dense. Therefore, in the filter 26t of the present embodiment, the toner collecting power of the high-density portion 26t1 is higher than the toner collecting power of the low-density portion 26t2.

[0032] Here, in the developing device 26 of this embodiment, the opening 26k1 is formed with an edge portion 26k10 (wall portion) extending in a communication direction from inside the device to outside the device (the ventilation direction, which is the vertical direction in Figures 2 and 4(A)). The filter 26t is installed in the opening 26k1 so that one end side (the side with lower weight density, which is the low-density portion 26t2) is located inside the device (the bottom side in Figure 4(A)) and the other end side (the side with higher weight density, which is the high-density portion 26t1) is located outside the device (the top side in Figure 4(A)). Moreover, the filter 26t is placed in the opening 26k1 with its non-air-permeable side (a surface through which air does not flow) in contact with the edge portion 26k10. 4(A) shows a two-dimensional view of the filter 26t being placed (fitted) in the opening 26k1 in contact with the edge 26k10. However, in reality, the filter 26t is placed in the opening 26k1 in a state where all four side surfaces are in contact with the substantially rectangular edge 26k10.

[0033] As shown in FIG. 4(B), in this embodiment, filter 26t is originally formed so that the weight density per unit volume at one end (lower in FIG. 4(B)) is lower than the weight density per unit volume at the other end (upper in FIG. 4(B)) when it is in a standalone state (as shown in FIG. 4(B) and not subjected to external force) that is not installed in opening 26k1 (high density portion 26t1 and low density portion 26t2 are formed). Specifically, the length N of the filter 26t in the intersecting direction when it is in a standalone state is set to be larger than the opening width M (length in the intersecting direction) of the opening 26k1 (N>M). 4(A), the filter 26t is placed in close contact with the opening 26k1 while being compressed to fit the shape of the opening 26k1. However, even when the filter 26t is placed in the opening 26k1, the weight density relationship between the high density portion 26t1 and the low density portion 26t2 is maintained.

[0034] 4(A), in this embodiment, at least one end side (lower in FIG. 4(A), which is low-density portion 26t2) of filter 26t is covered with non-breathable member 26u. In other words, at least one end side (low-density portion 26t2) of filter 26t is in contact with edge portion 26k10 of opening 26k1 via non-breathable member 26u. In detail, referring to FIG. 4(B), in the present embodiment, the portion of the low-density portion 26t2 that comes into contact with the edge portion 26k10 (the four side surfaces that are non-breathable surfaces) is covered all around with non-breathable member 26u. In this embodiment, the non-breathable member 26u is a film (a sheet-like member made of a resin material such as polyethylene terephthalate) having a thickness of about 0.1 to 2 mm. Specifically, a rectangular film with double-sided tape is wound around the side of the low-density portion 26t2 one or more times. At least the low-density portion 26t2 of the filter 26t is covered with a non-permeable member in a direction intersecting a direction from the inside to the outside of the developing device 26 (direction in which air is exhausted).

[0035] In this manner, in the developing device 26 in the present embodiment, at least the side surface (non-air permeable surface) of the low density portion 26t2 of the filter 26t is covered with the non-air permeable member 26u, so that the problem of the air (discharge target) in the developing device 26 leaking out together with the toner (collection target) from the side of the filter 26t (between the filter 26t and the opening 26k1) is reduced. Therefore, the function of the filter 26t described above is fully exerted, and the problem of the toner (collection target) scattering outside the developing device 26 is reduced. In detail, the filter 26t has a portion that has a low weight density per unit volume and is weakly adhered to the edge portion 26k10, and air is likely to leak out from the portion. In contrast, in the present embodiment, the portion is covered with the non-breathable member 26u to increase the adherence to the edge portion 26k10 (opening 26k1), thereby reducing such a problem. In this embodiment, the filter 26t is formed so that the weight density increases from the upstream side to the downstream side in the ventilation direction (communication direction) in order to facilitate the formation of an air flow from the inside to the outside of the developing device 26. This effectively prevents an increase in the internal pressure of the developing device 26, improves the overall toner collection ability of the filter 26t, and makes the filter 26t less likely to become clogged.

[0036] In this embodiment, the filter 26t is configured to be detachable from the outside of the developing device 26 (outside the device). Specifically, when installing filter 26t, filter 26 is moved in the direction of the white arrow from above developing device 26 (opening 26k1) as shown in FIG. 4(B), and filter 26t is fitted into opening 26k1 as shown in FIG. 4(A).

[0037] In this embodiment, a film is used as the non-breathable member 26u, but a material that hardens after being applied to the filter 26t (the side surface of the filter 26t) in a fluid state can also be used as the non-breathable member 26u. As a specific example, the air-impermeable member 26u can be made of UV-curable resin. More specifically, a flowable UV-curable resin is applied to the side surface of the low-density portion 26t2 of the filter 26t. The applied UV-curable resin is then irradiated with ultraviolet light to harden it. When the air-impermeable member 26u is made of UV-curable resin in this way, the cost of the components is higher than when the air-impermeable member 26u is made of a film, but the member is less likely to peel off from the filter 26t.

[0038] In the present embodiment, only the side surface of the low-density portion 26t2 of the filter 26t is covered with the air-impermeable member 26u. That is, the low-density portion 26t2 of the filter 26t is entirely covered with the air-impermeable member 26u. On the other hand, the entire periphery of the filter 26t in contact with the edge portion 26k10 may be covered with the non-breathable member 26u. That is, the filter 26t may be covered with the non-breathable member 26u. In this case, the filter 26t is covered with the non-breathable member 26u not only on the side surface (non-breathable surface) of the low density portion 26t2 but also on the side surface (non-breathable surface) of the high density portion 26t1. In such a case, the same effect as that described above can be obtained. However, if only the sides of the low-density portion 26t2 of the filter 26t are covered with the non-breathable material 26u, the positions of the high-density portion 26t1 and the low-density portion 26t2 become easier to distinguish, making it less likely that the filter 26t will be installed upside down in the opening 26k1.

[0039] In this embodiment, the filter 26t has a two-layer structure made up of a high-density portion 26t1 and a low-density portion 26t2. In contrast to this, as shown in FIG. 5 (particularly FIG. 5(A)), a filter 26t may be used that is formed so that the weight density per unit volume gradually increases in the direction of the arrow in FIG. 5 from one end side (the side inside the device) to the other end side (the side outside the device). Such a filter 26t is formed so that the weight density per unit volume gradually increases along the ventilation direction (exhaust direction). Specifically, the filter 26t shown in Fig. 5 has a relatively loose and fluffy mesh at one end and becomes denser toward the other end. Such a filter 26t can be manufactured, for example, by stacking a plurality of layers having different weight densities per unit volume. As shown in FIGS. 5(A) and 5(B), the entire periphery of the filter 26t in contact with the edge portion 26k10 is covered with the air-impermeable member 26u.

[0040] <Variation 1> 6, in the developing device 26 in the first modification, the edge of the opening 26k1 is formed so that the opening area of ​​the opening 26k1 decreases from the outside of the device to the inside of the device. Also in the first modification, at least the low-density portion 26t2 is in contact with the edge 26k10 via the non-breathable member 26u. In detail, the developing device 26 shown in FIG. 6(A) is formed such that the opening area of ​​the edge portion 26k10 becomes continuously smaller from the outside of the device to the inside of the device (from the top to the bottom of FIG. 6(A)). That is, edge 26k10 is inclined (an inclined surface is formed) away from the center of the opening from the upstream side in the discharge direction to the downstream side in the discharge direction with respect to the discharge direction (ventilation direction) in which air is discharged outside the device. By configuring the edge portion 26k10 in this manner, it becomes possible to compress the low-density portion 26t2, which is easily compressed, at a high compression ratio, thereby improving the adhesion to the opening 26k1. In addition, it becomes easier to assemble the filter 26t from the outside of the developing device 26, and easier to remove the filter 26t from the developing device 26. Furthermore, the lower end of the inclination of the edge portion 26k10 functions as a restricting portion that prevents the filter 26t from falling into the developing device 26. Even in this configuration, it is possible to reduce the problem that the air inside the developing device 26 is discharged to the outside of the device together with the toner without passing through the filter 26t.

[0041] In contrast, the developing device 26 shown in Figure 6(B) is formed so that the opening area of ​​the edge 26k10 gradually decreases from the outside of the device to the inside of the device (from the top to the bottom in Figure 6(B)). In detail, the opening 26k1 has a two-tier structure in which a first edge 26k11 with a large opening area is formed on the side outside the device (the upper side in Figure 6(B)), and a second edge 26k12 with a small opening area is formed on the side inside the device (the lower side in Figure 6(B)). The filter 26t is placed such that the high density portion 26t1 fits into the first edge portion 26k11, and the low density portion 26t2 contacts the second edge portion 26k12 via the air-impermeable member 26u. Even in this configuration, it is possible to reduce the problem that the air in the developing device 26 is discharged together with the toner to the outside of the device without passing through the filter 26t. Also, even in the case where the edge portions 26k11, 26k12 are formed so that the opening area is gradually reduced, the operability of attaching and detaching the filter 26t to and from the opening 26k1 from the outside of the device is improved, as in the case of Fig. 6(A), and the step of the edge portions 26k11, 26k12 makes it difficult for the filter 26t to fall off into the device.

[0042] <Variation 2> As shown in FIG. 7, the developing device 26 in the second modified example is formed with a restricting portion 26k15 that restricts the filter 26t from falling off from the opening 26k1 (edge ​​portion 26k10) into the device. Specifically, a limiting portion 26k15 that protrudes downward from the opening 26k1 (edge ​​portion 26k10) in the developing case 26k in a direction narrowing the opening is formed below the opening 26k1. The restricting portion 26k15 is formed so as to abut against one end side of the filter 26t (a portion having a low weight density, that is, the low-density portion 26t2). Providing the limiting portion 26k15 in this manner can prevent the filter 26t placed in the opening 26k1 from falling into the developing device 26. In addition, it becomes easier to determine the vertical position of the filter 26t in the opening 26k1. Furthermore, in the developing device 26 of the second modified example, a stopper member 26r is removably installed, which can abut against the outside of the filter 26t (the part with a high weight density, that is, the high density part 26t1) so as to prevent the filter 26t from falling out of the device through the opening 26k1 (edge ​​part 26k10). Specifically, in order to prevent the filter 26t from coming off upward, the stopper member 26r is fixed (screw-fastened) to the developing case 26k by a screw 90 so as to press the filter 26t from above. In addition, in the second modification, a plate-shaped member having an opening on the inside is used as the stopper member 26r, however, the stopper member 26r is not limited to this as long as it does not impair the function of the filter 26. For example, a mesh-like member with a coarse mesh can also be used as the stopper member 26r. Furthermore, in the second variant, the low-density portion 26t2 of the filter 26t is in contact with the edge portion 26k10 via the non-breathable member 26u, thereby reducing the problem of air within the developing device 26 being discharged outside the device together with the toner without passing through the filter 26t.

[0043] As described above, the developing device 26 in this embodiment is a filter holding device in which the filter 26t is installed in the opening 26k1 that communicates between the inside of the device and the outside of the device. The filter 26t is formed so that the weight density per unit volume at one end is lower than the weight density per unit volume at the other end. The filter 26t is installed in the opening 26k1 so that one end is located inside the device and the other end is located outside the device. Furthermore, at least one end of the filter 26t (the side with low weight density) is covered with a non-breathable member 26u that is not breathable. This can reduce the problem that the air (discharge target) inside the developing device 26 is discharged to the outside of the device together with the toner (collection target).

[0044] In the present embodiment, the developing device 26 is not a component of the process cartridge 20, but is a unit that can be attached to and detached from the image forming apparatus main body 1 alone. Alternatively, the developing device 26 can be one of the components of the process cartridge 20, and can be configured to be attached to and detached from the image forming apparatus main body 1 as a process cartridge. In such a case, the same effect as that of this embodiment can be obtained. In this application, a "process cartridge" is defined as a unit in which at least one of a charging device for charging an image carrier, a developing device for developing a latent image formed on the image carrier, and a cleaning device for cleaning the image carrier is integrated with an image carrier, and is configured to be detachable from the main body of an image forming apparatus.

[0045] In this embodiment, the present invention is applied to a developing device 26 in which two transport screws 26b1, 26b2 (transport members) are arranged side by side in the horizontal direction, and a doctor blade 26c is arranged below a developing roller 26a. However, the configuration of the developing device to which the present invention is applied is not limited to this, and the present invention can be applied to, for example, a developing device in which three or more transport members are arranged side by side in the horizontal direction, a developing device in which a plurality of transport members are arranged side by side in the vertical direction, or a developing device in which a doctor blade is arranged above a developing roller. In the present embodiment, the present invention is applied to the developing device 26 that uses a two-component developer made of toner and carrier. However, the present invention can also be applied to a developing device that uses a one-component developer made of only toner (including external additives, etc.). In these cases, the same effects as those of the present embodiment can be obtained.

[0046] In addition, in this embodiment, the present invention is applied to the developing device 26 as a filter holding device, but the filter holding device to which the present invention is applied is not limited to this, and can be applied to, for example, all devices that contain powder such as toner inside, such as toner container 70, waste toner collection container 80, cleaning device 23, intermediate transfer belt cleaning device 81, toner supply device, toner transport device, etc. In addition, in this embodiment, the present invention is applied to the developing device 26 as a filter holding device configured to collect toner as a collection target and discharge air as a discharge target outside the device, but the filter holding device (combination of a discharge target and a collection target) to which the present invention is applied is not limited to this. For example, the present invention can also be applied to the image forming device main body 1 as a filter holding device configured to collect ozone as a collection target and discharge air (air not containing ozone) as a discharge target outside the device. In these cases, the same effects as those of the present embodiment can be obtained.

[0047] It is clear that the present invention is not limited to the present embodiment, and that each embodiment may be appropriately modified within the scope of the technical concept of the present invention in addition to what is suggested in each embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and may be any number, position, shape, etc. suitable for implementing the present invention. [Explanation of symbols]

[0048] 1 Image forming apparatus (image forming apparatus main body), 20, 20Y, 20M, 20C, 20BK process cartridges, 21 photosensitive drum (image carrier), 26 Developing device (filter holding device), 26a developing roller (developer carrier), 26k developing case, 26k1 Openings (ventilation passages), 26k10 Edge (wall), 26k11, 26k12 edges, 26k15 Restriction section, 26t filter, 26t1 high density part, 26t2 low density part, 26u Non-breathable material, 26r Stopper part. [Prior art documents] [Patent documents]

[0049] [Patent Document 1] JP 2014-178347 A

Claims

1. A filter holding device in which a filter is installed in an opening that connects the inside of the device to the outside of the device, The filter comprises: A two-layer structure having a low density portion having a low weight density per unit volume formed at one end and a high density portion having a high weight density per unit volume formed at the other end, The opening is disposed such that the one end is located inside the device and the other end is located outside the device, A side surface of the low density portion is covered with a non-breathable member that is not air-permeable, A filter holding device characterized in that the non-breathable member is placed at the opening so as to be sandwiched between the opening and the side of the low-density portion, and the side of the high-density portion contacts the opening without the non-breathable member being interposed therebetween.

2. 2. The filter holding device according to claim 1, wherein the low density portion of the filter is entirely covered with the air-impermeable member.

3. 3. The filter holding device according to claim 1, wherein the air-impermeable member is a film.

4. 3. The filter holding device according to claim 1, wherein the air-impermeable member is a member that is applied to the filter in a fluid state and then hardens.

5. 5. The filter holding device according to claim 4, wherein the air-impermeable member is made of a UV-curable resin.

6. 6. The filter holding device according to claim 1, wherein an edge of the opening extends in a communication direction from inside the device to outside the device.

7. A developing device that contains toner and develops a latent image formed on a surface of an image carrier, A developing device comprising the filter holding device according to any one of claims 1 to 6.

8. A process cartridge that is detachably installed in a main body of an image forming apparatus, 8. A process cartridge comprising the developing device according to claim 7 and said image carrier integrally formed therewith.

9. 9. An image forming apparatus comprising at least one of the filter holding device according to claim 1, the developing device according to claim 7, and the process cartridge according to claim 8.

10. A filter that is installed in an opening that connects the inside of the device to the outside of the device, The composite material has a high density portion having a high weight density per unit volume and a low density portion having a low weight density per unit volume, The low-density portion has a non-permeable side covered with a non-permeable member that is not permeable, A filter characterized in that the non-breathable member is placed at the opening so as to be sandwiched between the opening and a side surface of the low-density portion, and the side surface of the high-density portion contacts the opening without the non-breathable member being interposed therebetween.

11. The filter according to claim 10, wherein the non-breathable member is a film.

12. 11. The filter according to claim 10, wherein the air-impermeable member is a member that is applied to the filter in a fluid state and then hardens.

13. 13. The filter according to claim 12, wherein the air-impermeable member is made of a UV-curable resin.

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