Developing device, process cartridge, and image forming apparatus

Abstract

To cause air to flow smoothly from the inside of a filter device to the outside of the device, and reduce the problem that a toner collected to the filter scatters when the filter is removed from a developing device.SOLUTION: A development case 26k is provided, in which an opening 26k1 for allowing the inside and the outside of a developing device to communicate is formed. A filter holding member 26s for holding a filter 26t is installed in the opening 26k1. The filter 26t is formed in such a way that the weight density per unit volume on the inside of the device is lower than the weight density per unit volume on the outside of the device. Meanwhile, the filter holding member 26s is constituted so as to be attachable / removable from the development case 26k while the filter 26t is held in place.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a developing device that accommodates a developer such as a two-component developer, and a process cartridge and an image forming apparatus that include the same. [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 top 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 prevented. 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 the conventional technology, the flow of air from the inside to the outside of the device through the filter was not very good, and therefore the increase in internal pressure of the developing device was not effectively suppressed. Furthermore, with conventional technology, when the filter is removed from the developing device for maintenance or other purposes, the filter can become deformed and curved, causing the toner trapped in the filter to scatter and soil the surrounding area.

[0005] This invention has been made to solve the above-mentioned problems, and aims to provide a developing device, a process cartridge, and an image forming device in which air flows smoothly from the inside of the filter to the outside of the device, and in which the problem of toner captured in the filter scattering when the filter is removed from the developing device is reduced. [Means for solving the problem]

[0006] The developing device of the present invention is a developing device in which a developer is stored within the device and which develops a latent image formed on the surface of an image carrier, and includes a developing case formed with an opening which allows the inside of the device to communicate with the outside of the device, and a filter holding member which is installed in the opening and holds a filter, The aforementioned The filter holding member is configured to be detachable from the developing case while holding the filter. and a rectangular parallelepiped bottom surface portion located inside the device and having one or more through holes formed therein, and three side wall portions extending from three of the four sides of the bottom surface portion toward the outside of the device, the developing case includes an opposing wall portion that is a part of an edge portion of the opening and that faces one of the three side wall portions; The filter is formed so that the weight density per unit volume inside the device is lower than the weight density per unit volume outside the device, and is sandwiched and compressed between the three side wall portions and the opposing wall portion. It is something. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a developing device, a process cartridge, and an image forming device in which air flows smoothly from the inside of the filter to the outside of the device, and the problem of toner captured in the filter scattering when the filter is removed from the developing device is reduced. [Brief explanation 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; [Figure 2] FIG. [Figure 3] FIG. 2 is a longitudinal view of the developing device. [Figure 4] 1A and 1B are an enlarged cross-sectional view and an enlarged top view, respectively, showing a state in which a filter is installed in an opening of a developing device together with a filter holding member. [Figure 5] FIG. 10 is a cross-sectional view showing a filter according to another embodiment. [Figure 6] 1A is a diagram showing a state in which the filter is being removed from the developing device together with the filter holding member, and FIG. 1B is a diagram showing a state in which the filter is being removed from the filter holding member. [Figure 7] 1A is a diagram showing the state in which the filter is removed from the developing device together with the filter holding member in this embodiment, and FIG. 1B is a diagram showing the state in which the filter is removed alone from the developing device as a comparative example. [Figure 8] FIG. 2 is a diagram showing a new developing device at the time of shipment from the factory. [Figure 9] FIG. 10 is a diagram showing a new developing device at the time of shipping from a factory, as a first modified example. [Figure 10] FIG. 10 is an enlarged cross-sectional view showing a state in which a filter holding member is installed together with a filter in an opening of a developing device, according to a second modification. [Figure 11] FIG. 11 is an enlarged cross-sectional view showing a state in which a filter holding member is installed together with a filter in an opening of a developing device, according to a third modification. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations 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 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) is installed so as to face the photosensitive drums 21 of the plurality of process cartridges 20Y, 20M, 20C, and 20BK.

[0011] In Figure 1, 1 indicates the main body of a color copier as an image forming device, 2 indicates a document transport unit that transports a document to a document reading unit 3, 3 indicates a document reading unit that reads image information from the document, and 4 indicates a writing unit (exposure unit) that emits laser light based on input image information. Also, 20Y, 20M, 20C, and 20BK indicate process cartridges corresponding to the respective colors (yellow, magenta, cyan, and black), and 40 indicates an intermediate transfer belt onto which toner images of multiple colors are transferred in an overlapping manner. Also, 61 denotes a paper feed 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 to the sheet P, and 66 denotes a fixing device that fixes the unfixed image on the sheet P. Also, 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 80 denotes a waste toner collection container in which untransferred toner collected by the cleaning device 23 (see Figure 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 integrates 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 opposite the photosensitive drum 21 of each process cartridge 20Y, 20M, 20C, and 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, and 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 the image information of the document placed on the contact glass. Then, the image information for each color of yellow, magenta, cyan, and black is sent to the writing unit 4. Then, from the writing unit 4, laser light L (exposure light) based on the image information for each color is irradiated onto the surface of the photosensitive drum 21 (see FIG. 2) of the corresponding process cartridge 20Y, 20M, 20C, 20BK.

[0014] Meanwhile, each of the four photosensitive drums 21 rotates clockwise in FIGS. 1 and 2. First, the surface of each photosensitive 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 photosensitive drum 21. Thereafter, the charged surface of each photosensitive drum 21 reaches a position where a laser beam is irradiated 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 photosensitive 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 photosensitive 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 photosensitive drum 21 after it has been charged by the charging device 22. Similarly, the cyan laser light is irradiated onto the surface of the photosensitive drum 21 of the process cartridge 20C, which is the second from the left on the paper, and an electrostatic latent image of the cyan component is formed. The magenta laser light is irradiated onto the surface of the photosensitive drum 21 of the process cartridge 20M, which is the third from the left on the paper, and an electrostatic latent image of the magenta component is formed. The black laser light is irradiated onto the surface of the photosensitive drum 21 of the process cartridge 20BK, which is the fourth from the left on the paper, and an electrostatic latent image of the black component is formed.

[0016] Thereafter, the surface of the photosensitive drum 21 on which the electrostatic latent image of each color is formed reaches a position facing the developing device 26. Then, toner of each color is supplied from each developing device 26 onto the photosensitive drum 21, and the latent image on the photosensitive drum 21 is developed (this is the developing process). Thereafter, the surfaces of the photosensitive drums 21 after the development process reach positions facing the intermediate transfer belt 40. Here, primary transfer rollers 24 are installed 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 photosensitive 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] After the primary transfer process, the surfaces of the photosensitive drums 21 reach a position facing the cleaning devices 23. The cleaning devices 23 then collect untransferred toner remaining on the photosensitive drums 21 (this is the cleaning process). The untransferred toner collected by the cleaning devices 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 removal device, and a series of image forming processes on the photosensitive drum 21 is completed.

[0018] Meanwhile, the surface of the intermediate transfer belt 40 onto which the images of each color on the photosensitive 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 the 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. More specifically, a sheet P fed by a paper feed roller 62 from a paper feed device 61 that stores sheets P passes through a conveyance 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 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 FIGS. The four image forming units installed in the image forming apparatus main body 1 have almost the same structure except for the color of the 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 photosensitive drum 21 is a negatively charged organic photosensitive member, and is formed by providing a photosensitive layer and the like on a drum-shaped conductive support. The charging device 22 is a charging roller made of a conductive core metal and a medium-resistance elastic layer coated on the outer periphery thereof. A predetermined voltage is applied to the charging device 22 (charging roller) from a power supply unit, thereby uniformly charging the surface of the opposing photosensitive drum 21. The cleaning device 23 is equipped with a cleaning blade 25a and a cleaning roller 25b that come into contact with the photosensitive 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 photosensitive 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 to regulate the amount of developer carried on the developing roller 26a. The developing device 26 in this embodiment is provided with a filter 26t and a filter holding member 26s, which will be described in detail later.

[0024] The developing device 26 contains a developer (two-component developer) made up of carrier and 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 (the circulation path indicated by the dashed arrow in FIG. 3). That is, a developer circulation path 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 longitudinal end portions of the two transport paths B1 and B2 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. Furthermore, 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. In other words, the partition member 26e is disposed at a position excluding both longitudinal end portions. The first transport screw 26b1 (first transport path B1) is disposed opposite the developing roller 26a, and the second transport screw 26b2 (second transport path B2) is disposed opposite 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 post-development developer that has been released from the developing roller 26a. The second transport screw 26b2 agitates and mixes the post-development developer transported from the first transport path B1 with 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 rotation shaft.

[0026] In this embodiment, the developing device 26 is covered by two developing cases (an upper developing case 26k and a lower developing case 26j) that can be separated into upper and lower parts. The developing roller 26a, the first and second transport screws 26b1, and the doctor blade 26c are rotatably held in the developing lower case 26j. Furthermore, the developing upper case 26k has a filter holding member 26s that holds a filter 26t in an opening 26k1, as will be described later. The developing upper case 26k is detachably mounted by screwing or snapping to the developing lower case 26j in which the developing roller 26a, the first and second transport screws 26b1, and the doctor blade 26c are mounted.

[0027] The image forming process described above will now be explained in more detail, focusing on the development process. Developing roller 26a rotates in the direction of the arrow in Fig. 2. As shown in Fig. 3, the developer in developing device 26 is circulated in the longitudinal direction while being stirred and mixed with toner supplied from toner container 70 through supply port 26d via the toner supply path by rotation in the direction of the arrow of first transport screw 26b1 and second transport screw 26b2, which are arranged with partition member 26e interposed therebetween (circulation in the direction of the dashed arrow in Fig. 3). The toner, which has been frictionally charged and attracted to the carrier, is then lifted up onto the developing roller 26a together with the carrier by a developer lift-up 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 until it reaches a position facing the doctor blade 26c. The developer on the developing roller 26a is then adjusted to an appropriate amount at this position and then transported to a position facing the photosensitive drum 21 (the developing area). The toner is then attracted to the latent image formed on the photosensitive drum 21 by an electric field formed in the developing area. The developer remaining on the developing roller 26a then reaches above the first transport path B1 as the sleeve rotates and is detached from the developing roller 26a at this position. The electric field in the developing area is formed by a predetermined voltage (developing bias) applied to the developing roller 26a by a development power supply and a surface potential (latent image potential) formed on the surface of the photosensitive drum 21 during the charging and exposure processes.

[0028] 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 proportion of toner in the developer). The supply port 26d is provided at one end of the second transport screw 26b2 in the longitudinal direction (the left-right direction in FIG. 3), above the second transport screw 26b2 (second transport path B2).

[0029] The configuration and operation of the developing device 26, which is a feature of this embodiment, will be described in detail below. 2, 4, etc., developing device 26 in the present embodiment has filter holding member 26s that holds filter 26t disposed in opening 26k1 that connects the inside of the device with the outside of the device. More specifically, an opening 26k1 (ventilation path) penetrating from the inside to the outside is formed in the ceiling of the upper developer case 26k (housing) serving as the developer case of the developing device 26. A filter 26t (and a filter holding member 26s) is provided to close the opening 26k1. The filter 26t is used to collect powder toner and allow ventilation. 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 upper case 26k. The filter 26t (and the filter holding member 26s) is installed at the opening 26k as an attachment portion. The filter 26t is made of a mesh that is smaller than the particle size of the toner T and the carrier C, and is formed so that only air can pass through. In this embodiment, the opening 26k1 is a substantially rectangular opening, and the filter 26t (single filter) is formed in a substantially rectangular parallelepiped shape. In this embodiment, the filter 26t is detachably held by a filter holding member 26s, which will be described in detail later.

[0030] Referring to FIG. 2, the gap H (casing gap) between the developing roller 26a and the upper developing case 26k on the downstream side of the developing area is set to be within a range of 0.6 to 1.0 mm. If the casing gap H becomes smaller than 0.6 mm, the developer carried on the developing roller 26a after the development process will not be smoothly transported to the gap H between the developing roller 26a and the developing upper case 26k, and will easily overflow and leak out of the developing device 26. On the other hand, if the casing gap H is larger than 1.0 mm, it becomes difficult for the developer carried by the developing roller 26a to slide against the inner surface of the developing upper case 26k, making it difficult for a suction airflow toward the inside of the developing device 26 due to the pump action, and toner scattering from the developing device 26 (toner scattering around the development area) becomes more likely to occur. By maintaining the casing gap H within an appropriate range, developer leakage and toner scattering 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.

[0031] Here, in this embodiment, filter 26t is formed so that the weight density per unit volume inside the device (lower in Figures 2 and 4(A)) is lower than the weight density per unit volume outside the device (upper in Figure 4(A)). That is, the weight density per unit volume of filter 26t is not uniform, but rather there are low and high weight density areas in the ventilation direction (the direction in which air flows from inside the device to outside the device, which is the communication direction.) In other words, filter 26t has a gradient in weight density per unit volume. The state in which filter 26t has a weight density gradient remains the same whether it is in a standalone state not installed in opening 26k1 (a standalone state in which no external force is acting) or in a state in which it is installed in opening 26k1.

[0032] More specifically, in this embodiment, filter 26t, when not installed in opening 26k, is a two-layer structure in which a low-density portion 26t2 having a low weight density per unit volume is formed at one end and a high-density portion 26t1 having a high weight density per unit volume is formed at the other end. That is, in the filter 26t, the low-density portion 26t2 at one end (upstream side in the airflow direction) is coarse and relatively fluffy, while the high-density portion 26t1 at the other end (downstream side in the airflow direction) is dense. Therefore, in the filter 26t of this embodiment, the toner collecting power of the high-density portion 26t1 is higher than that of the low-density portion 26t2.

[0033] In this way, by forming the filter 26t so that the weight density increases from the upstream side to the downstream side in the air passage direction (communication direction), it becomes easier to form a smooth air flow from the inside to the outside of the developing device 26. As a result, an increase in the internal pressure of the developing device 26 is efficiently suppressed, the overall toner collection ability of the filter 26t can be improved, and further, clogging of the filter 26t becomes less likely to occur.

[0034] In this embodiment, the filter 26t has a two-layer structure consisting of a high-density portion 26t1 and a low-density portion 26t2. Alternatively, as shown in Fig. 5(A), the filter 26t may have a single-layer structure in which the weight density per unit volume gradually increases from one end (inside the device) to the other end (outside the device) in the direction of the arrow in Fig. 5(A). 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(A) has a relatively loose and fluffy mesh at one end and a denser mesh toward the other end. 5(B), the filter 26t may have a multi-layer structure of three or more layers formed so that the weight density per unit volume increases from one end (inside the device) to the other end (outside the device). Such a filter 26t has multiple layers 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(B) has a relatively loose and fluffy mesh at one end, and layers with denser mesh are stacked toward the other end.

[0035] As shown in FIG. 4 and other figures, in the developing device 26 of this embodiment, a filter holding member 26s that holds a filter 26t is installed in an opening 26k1 of an upper developing case 26k (developing case). 6(A), 7(A), etc., in this embodiment, the filter holding member 26s is configured to be detachable from the developer upper case 26k (developer case) while holding the filter 26t. That is, the filter 26t is not attached to or detached from the upper developing case 26k alone as shown in Figure 7(B), but is removed together with the filter holding member 26s in the direction of the white arrow as shown in Figures 6(A) and 7(A), or attached in the opposite direction.

[0036] Specifically, as shown in FIG. 4, the filter holding member 26s is a substantially box-shaped member consisting of a bottom portion 26s1 and three side wall portions 26s2 to 26s4, with one side wall portion and the ceiling portion missing, and is made of a resin material. The filter holding member 26s is approximately L-shaped when viewed in a cross section perpendicular to the longitudinal direction as shown in Figure 4(A), and has side wall portions 26s2 to 26s4 that are approximately U-shaped when viewed from above as shown in Figure 4(B).

[0037] The bottom surface 26s1 of the filter holding member 26s is located inside the device (at the bottom in FIG. 4(A)) and is formed in a rectangular parallelepiped (rectangular plate) shape. The bottom surface 26s1 has a plurality of through-holes 26s10 formed therein for allowing ventilation from inside the device to the filter 26t. Note that the bottom surface 26s1 may have only one through-hole 26s10 as long as it can hold the filter 26t and allow ventilation from inside the device to the filter 26t. The three side walls 26s2 to 26s4 of the filter holding member 26s stand upright from three of the four sides of the bottom surface 26s1 toward the outside of the device (upper side in FIG. 4(A)). 4, 6A, etc., the upper developing case 26k (developing case) is formed with an opposing wall 26k10 that faces one side wall 26s2 (a side wall extending in the longitudinal direction) of the three side walls 26s2 to 26s4 of the filter holding member 26s. This opposing wall 26k10 functions as a part of the edge of the opening 26k1. The filter holding member 26s is disposed to face the developing roller 26a via this opposing wall 26k10.

[0038] The filter 26t is sandwiched and compressed between the three side walls 26s2 to 26s4 of the filter holding member 26s and the opposing wall 26k10 (part of the edge of the opening 26k1) of the upper developing case 26k. That is, filter 26t placed in opening 26k1 is compressed from all four sides (directions intersecting the communication direction, see the black arrows in FIG. 4(A)) by three side wall portions 26s2 to 26s4 and opposing wall portion 26k10. In other words, filter 26t is placed in opening 26k1 in a compressed state from a standalone state. This reduces the problem of air (object to be discharged) leaking out of the developing device 26 together with toner (object to be collected) from the side of the filter 26t (only air is discharged). Therefore, the function of the filter 26t described above is fully exerted, and the problem of toner (object to be collected) scattering outside the developing device 26 is reduced.

[0039] Referring to FIG. 4 and other figures, the upper developer case 26k (developer case) is provided with a seal member 26w that seals gaps between the opening 26k1 and the three side walls 26s2 to 26s4 of the filter holding member 26s. In detail, the sealing member 26w is made of an elastic material such as foamed polyurethane, and is a roughly U-shaped member when viewed from above as shown in Figure 4(B), and is attached to the opening 26k1 of the upper developing case 26k via double-sided tape. By providing the sealing member 26w in this manner, the problem of air (discharge target) leaking together with toner (collection target) from inside the developing device 26 through the gap between the filter holding member 26s and the opening 26k1 is reduced. Therefore, the function of the filter 26t described above is fully exerted, and the problem of toner (collection target) scattering outside the developing device 26 is reduced.

[0040] In addition, since the opposing wall portion 26k10 and the filter 26t are in close contact with each other, air does not leak out from that portion together with the toner. Furthermore, the end of the sealing member 26w is flattened and fits into the gap between the end faces of the side walls 26s3 and 26s4 extending in the lateral direction and the opposing wall 26k10, so that the problem of air leaking out from that portion together with the toner is unlikely to occur. However, a sealing material (which may be part of the sealing member 26w) that actively seals the gap between the end faces of the side walls 26s3 and 26s4 extending in the lateral direction and the opposing wall 26k10 may be provided.

[0041] In this manner, in the developing device 26 according to the present embodiment, the filter holding member 26s is configured to be detachable from the developing upper case 26k while holding the filter 26t, thereby reducing the problem of the toner T collected in the filter 26t scattering when the filter 26t is removed from the developing device 26 for maintenance or the like. More specifically, as shown as a comparative example in Figure 7(B), when the filter 26t is removed from the developing device 26 by itself, the filter 26t, which is long in the longitudinal direction, becomes deformed and curved, causing the toner T captured by the filter 26t to be pushed out and scattered, soiling the surrounding area. In contrast, in the present embodiment, the filter 26t is held by the filter holding member 26s and is removed from the developing device 26 in an undeformed state, thereby reducing the problem of the toner T captured by the filter 26t scattering and soiling the surrounding area. In particular, the filter 26t in this embodiment has a weight density gradient as described above, and therefore has an improved toner collection capability, making the configuration of the present invention particularly useful.

[0042] In the present embodiment, the filter holding member 26s does not have four side walls, but has three side walls 26s2 to 26s4, with one side wall missing, but the area of ​​the bottom surface 26s1 is large enough to hold the filter 26t. Therefore, when the filter 26t is attached to or detached from the developing device 26 together with the filter holding member 26s, the filter 26t is unlikely to accidentally fall off the filter holding member 26s.

[0043] 6(B), in this embodiment, the filter 26t is configured to be detachable (replaceable) from the filter holding member 26s, which makes it easy to perform maintenance such as replacing and cleaning the filter 26t. Specifically, as shown in FIG. 6B, the filter 26t is attached to and detached from the filter holding member 26s in a state where the filter holding member 26s is removed from the developing device 26. At this time, since the filter holding member 26s is missing one side wall portion as described above, the filter 26t can be easily attached and detached to and from the filter holding member 26s in a state where it has been removed from the developing device 26.

[0044] Here, as shown in Figure 4(B), the filter holding member 26s is provided with a rotary stopper 26r as a restricting member that can move between a restricting position (the position shown in Figure 4(B)) that restricts the filter 26t from being removed and a non-restricting position that allows the filter 26t to be removed. Specifically, the rotary stopper 26r (restriction member) is installed on the upper surfaces of the two side wall portions 26s3, 26s4 at both ends in the longitudinal direction so as to be rotatable about a support shaft 26r1. When the rotary stopper 26r is rotated to the position (restriction position) shown in FIG. 4(B), the filter 26t comes into contact with the rotary stopper 26r, thereby restricting the filter 26t from falling out of the filter holding member 26s. On the other hand, when the rotary stopper 26r is rotated 90 degrees or more clockwise (or counterclockwise) about the support shaft from the restriction position shown in FIG. 4(B) (moves to the restriction release position), the filter 26t can be removed from the filter holding member 26s without coming into contact with the rotary stopper 26r. This configuration prevents the filter 26t from coming off the filter holding member 26s while the developing device 26 is in operation, and also makes it possible to remove the filter 26t from the filter holding member 26s as previously described using Figure 6(B).

[0045] Also, referring to Figures 4(B), 7(A), etc., the developing device 26 in this embodiment is provided with a screw 90 as a restricting member that restricts the filter holding member 26s from coming out of the device through the opening 26k1. More specifically, the filter holding member 26s has protrusions (with screw holes) that protrude outward in the longitudinal direction formed on the upper portions of two side wall portions 26s3 and 26s4 at both ends in the longitudinal direction. Meanwhile, the developer upper case 26k has female threads formed in the portions where the protrusions of the side wall portions 26s3 and 26s4 are placed. Then, a screw 90 is threaded into the female threads of the developer upper case 26k through the protrusions (screw holes), thereby fixing the filter holding member 26s to the developer upper case 26k. When the filter holding member 26s together with the filter 26t is removed from the developing device 26 (developer upper case 26k), the screw 90 is released from its threaded state, as shown in FIG. 7A. In this embodiment, the filter holding member 26s is fixed to the upper developing case 26k by screw fastening, but the method of fixing the filter holding member 26s to the upper developing case 26k is not limited to this, and it can also be fixed by, for example, snap fastening.

[0046] Referring now to Figure 8, in the developing device 26 of this embodiment, a sheet-like member 26x is removably installed to isolate the inside of the device so that a closed space containing developer G is formed within the developing device, so that developer G (which is a preset developer pre-filled at the time of shipment from the factory) contained inside the developing device 26 does not leak out until use in the image forming device main body 1 begins. This sheet-like member 26x is installed so that it passes from inside the device between the opening 26k1 and the filter holding member 26s (between the sealing member 26w attached to the opening 26k1 and the side wall portion 26s2) and one end is exposed outside the device. Then, when a user starts using the developing device 26 in the image forming device main body 1, the portion of the sheet-like member 26x exposed outside the developing device is grasped, and the sheet-like member 26x is pulled out from inside the developing device 26.

[0047] Specifically, sheet-like member 26x is made of a transparent resin material such as an OHP sheet or Mylar having a thickness of about 0.1 to 0.5 mm, and is formed into a substantially rectangular shape so as to extend in the pulling-out direction (the direction of the white arrow in FIG. 8). Sheet-like member 26x has a width length set to match the width range of the interior so as to isolate the interior of developing device 26, and the portion exposed to the outside of the device is set to be sufficiently long while isolating the interior of developing device 26.

[0048] A new developing device 26 (including a recycled product) is shipped from the factory with the sheet-like member 26x installed, as shown in Fig. 8. That is, after developer G is filled into the interior (first and second transport paths B1, B2) of the developing device 26 in an assembled state at the factory, the sheet-like member 26x is installed to block the gap between the first transport path B1 and the developing roller 26a to prevent the developer G from leaking. 8, in this embodiment, the sheet-like member 26x is formed inside the developing device 26 so as to cover the entire longitudinal area between the tip of the doctor blade 26c and the left edge of the opening 26k1. The vicinity of one end of the sheet-like member 26x on the doctor blade 26c side is adhered (or heat-sealed) with a relatively light force to the developing device 26 (the tip of the doctor blade 26c in this embodiment), and the vicinity of the other end of the sheet-like member 26x is sandwiched between the filter holding member 26s and the opening 26k1 (seal member 26w), applying tension to the sheet-like member 26x. This prevents the developer G from leaking out toward the developing roller 26a.

[0049] In this manner, in this embodiment, instead of forming a dedicated opening for exposing one end of the sheet-shaped member 26x to the outside of the device, the opening 26k1 is shared with the filter 26t, thereby simplifying the configuration of the device. Furthermore, since the opening 26k1 is relatively large, the sheet-like member 26x can be easily placed in the developing device 26 during manufacturing. Furthermore, the sheet-like member 26x contacts the edge of the opening 26k1 of the developing case 26k on the side where a closed space is to be formed (the left edge in FIG. 8) via the seal member 26w, thereby improving the airtightness of the closed space formed in the developing device 26. Furthermore, when the sheet-shaped member 26x is pulled out at the start of use of the developing device 26, the sheet-shaped member 26x comes into sliding contact with the seal member 26w, which cleans off the toner adhering to the sheet-shaped member 26x. This prevents the user's hands from getting dirty when pulling out the sheet-shaped member 26x.

[0050] <Variation 1> As shown in FIG. 9, a new developing device 26 in the first modified example is also provided with a sheet-like member 26x for forming a closed space for accommodating the preset developer G, similar to the developing device in FIG. Here, in the developing device 26 in Modification 1, a winding shaft 26p is rotatably installed on the top surface of the developing upper case 23k. An end portion (a portion exposed to the outside of the device) of the sheet-like material 26x is fixed to the winding shaft 26p by adhesive or the like so that the sheet-like material 26x can be wound around the outer periphery of the winding shaft 26p by rotating the winding shaft 26p. Developing device 26 configured in this manner is mounted to image forming apparatus main body 1 with developer G contained therein and sealed within sheet-like member 26x, as shown in Fig. 9. Such cases include (1) a case where a new developing device 26 is mounted on a new image forming apparatus main body 1 before shipment, and (2) a case where a new (replacement) developing device 26 is mounted on an image forming apparatus main body 1 that has already been used by a user. In either case described above, the winding shaft 26p is rotated by a drive mechanism (not shown) to wind up the sheet-like material 26x in a sealed state onto the winding shaft 26p before the start of use (developing process) of a new developing device 26 in the image forming apparatus 1. That is, as shown in Fig. 9, in a state in which the developing device 26 having the sheet-like material 26x in a sealed state is mounted on the image forming apparatus main body 1, the winding shaft 26p is driven to rotate before the start of the image forming operation (developing process), so that the sheet-like material 26x is moved in the direction of the white arrow and wound up onto the winding shaft 26p, and the normal image forming process (developing process) is performed in the state shown in Fig. 2. Also in Modification 1, the filter holding member 26s is configured to be detachable from the developing case 26k while holding the filter 26t, which allows air to flow smoothly from the inside of the filter 26t to the outside of the device, and reduces the problem of toner T collected on the filter 26t scattering when the filter 26t is removed from the developing device 26.

[0051] <Variation 2> As shown in Figure 10, in the developing device 26 of variant example 2, the filter holding member 26s has an upright wall portion 26s5 that stands up from one side (the side facing the opposing wall portion 26k10) of the four sides of the bottom surface portion 26s1 on which three side wall portions 26s2 to 26s4 are not formed, toward the inside of the device (the bottom of Figure 10). That is, as shown in FIG. 10, the filter holding member 26s is formed in a crank shape (approximately S-shape) when viewed in a cross section perpendicular to the longitudinal direction. Providing the upright wall portion 26s5 in this manner can reduce the problem of the filter holding member 26s warping in the longitudinal direction, so that the filter 26t is held by the filter holding member 26s in a straight state, allowing the filter 26t to function normally. As shown in FIG. 10, in the developing device 26 of the second modified example, instead of a screw 90, a pressing member 26z (having a ventilation hole formed therein) that presses down on the filter holding member 26s together with the filter 26t from above serves as a restricting member that restricts the filter holding member 26s from coming out of the device through the opening 26k1, and is detachably attached to the developing upper case 26k by snapping or the like. As shown in FIG. 10, the developing device 26 in Modification 2 is formed so that the opposing wall portion 26k10 of the upper developing case 26k extends to a position (above) that is sufficiently higher than the upper surfaces of the filter holding member 26s and the filter 26t. Also in Modification 2, the filter holding member 26s is configured to be detachable from the developing case 26k while holding the filter 26t, which allows air to flow smoothly from the inside of the filter 26t to the outside of the device, and reduces the problem of toner T collected on the filter 26t scattering when the filter 26t is removed from the developing device 26.

[0052] <Variation 3> As shown in Figure 11, the filter holding member 26s in variant 3, like that in variant 2, is provided with an upright wall portion 26s5 that stands up toward the inside of the device from one of the four sides of the bottom surface portion 26s1 on which three side wall portions 26s2 to 26s4 are not formed. As shown in FIG. 11, the filter holding member 26s in the third modification is formed with one or more ribs 26s6 that connect the bottom surface portion 26s1 and the upright wall portion 26s5 inside the device. By providing the rib 26s6 in this manner, the problem of the filter holding member 26s warping in the longitudinal direction can be further alleviated.

[0053] As described above, the developing device 26 in this embodiment is a developing device that contains developer and develops a latent image formed on the surface of the photosensitive drum 21 (image carrier), and is provided with a developing case 26k having an opening 26k1 that connects the inside of the device to the outside of the device. A filter holding member 26s that holds a filter 26t is installed in the opening 26k1. The filter 26t is formed so that the weight density per unit volume inside the device is lower than the weight density per unit volume outside the device. The filter holding member 26s is configured to be detachable from the developing case 26k while holding the filter 26t. This allows air to flow smoothly from the inside of the filter 26t to the outside of the device, and reduces the problem of toner T trapped on the filter 26t scattering when the filter 26t is removed from the developing device 26.

[0054] 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 independently. However, the developing device 26 can also be one of the components of the process cartridge 20, and configured to be attached 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 that integrates at least one of a charging device that charges an image carrier, a developing device that develops a latent image formed on the image carrier, and a cleaning device that cleans the image carrier, with an image carrier, and is configured to be detachable from the image forming apparatus main body.

[0055] In this embodiment, the present invention is applied to a developing device 26 in which two transport screws 26b1 and 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 also 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 multiple 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 this embodiment, the present invention is applied to a developing device 26 that uses a two-component developer consisting of toner and carrier. However, the present invention can also be applied to a developing device that uses a one-component developer consisting only of toner (including external additives, etc.). In this case, the developing device can be configured so that the developing roller comes into contact with the photosensitive drum (image carrier). In such cases, the same effect as that of this embodiment can be obtained.

[0056] It is clear that the present invention is not limited to the present embodiment, and that within the scope of the technical concept of the present invention, each embodiment may be appropriately modified 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 the number, position, shape, etc. of the components may be any number, position, shape, etc. that is suitable for implementing the present invention. [Explanation of symbols]

[0057] 1 Image forming apparatus (image forming apparatus main body), 20, 20Y, 20M, 20C, 20BK process cartridges, 21 photosensitive drum (image carrier), 26 developing device, 26a developing roller (developer carrier), 26j Developing case, 26k developing case (developing case), 26k1 Openings (ventilation passages), 26k10 Opposing wall (edge), 26s filter holding member, 26s1 bottom part, 26s2~26s4 side wall part, 26s5 Standing wall section, 26s6 rib, 26s10 Through hole part, 26t filter, 26t1 high density part, 26t2 low density part, 26r Rotary stopper (regulating member), 26w sealing material, 26x sheet materials, 26z Restriction member (restriction member), 90 screws (restriction members), T Toner. [Prior art documents] [Patent documents]

[0058] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-178347

Claims

1. A developing device that contains a developer and develops a latent image formed on a surface of an image carrier, a developing case having an opening for communicating the inside of the device with the outside of the device; a filter holding member disposed in the opening and holding a filter; Equipped with the filter holding member is configured to be detachable from the developing case while holding the filter, and includes a rectangular parallelepiped bottom surface portion located inside the device and having one or more through holes formed therein, and three side wall portions extending from three of the four sides of the bottom surface portion toward the outside of the device, the developing case includes an opposing wall portion that is a part of an edge portion of the opening and that faces one of the three side wall portions; The filter is formed so that the weight density per unit volume inside the device is lower than the weight density per unit volume outside the device, and is compressed by being sandwiched between the three side wall portions and the opposing wall portion.

2. A developing roller facing or contacting the image carrier, 2. The developing device according to claim 1, wherein the filter holding member is disposed so as to face the developing roller with the opposing wall portion interposed therebetween.

3. A developing device as described in claim 1 or claim 2, characterized in that the filter holding member has an upright wall portion that rises toward the inside of the device from one of the four sides of the bottom portion on which the three side wall portions are not formed.

4. A developing device as described in Claim 3, characterized in that the filter holding member has a rib formed between the bottom portion and the upright wall portion inside the device.

5. A developing device described in any one of claims 1 to 4, characterized in that the developing case is provided with a sealing member that seals the gap between the opening and the three side wall portions of the filter holding member.

6. A developing device as described in any one of claims 1 to 5, characterized in that the filter holding member is provided with a regulating member that is movable between a regulating position that prevents the filter from coming off and a deregulating position that allows the filter to be removed.

7. A sheet-like member is detachably installed to isolate the inside of the device so that a closed space containing a developer is formed inside the device, The developing device according to any one of claims 1 to 5, characterized in that the sheet-like member is installed so that one end side is exposed to the outside of the device by passing from inside the device between the opening and the filter holding member.

8. A developing device as described in any one of claims 1 to 7, characterized in that it is provided with a restricting member that restricts the filter holding member from coming out of the device through the opening.

9. A process cartridge detachably installed in an image forming apparatus body, 9. A process cartridge comprising the developing device according to claim 1 and the image carrier, the process cartridge being integrally provided with the developing device.

10. An image forming apparatus comprising the developing device according to claim 1.

Images