Developing device, process cartridge, and image forming apparatus

Abstract

To reduce the occurrence of a trouble that toner leaks to the outside of a device from an opening for a sheet in a developing side plate formed to remove a sheet-like member.SOLUTION: A developing device is provided with a first developing side plate 26k1 that is formed with a D-hole part 26k10 (magnet positioning part) determining the posture in a circumference direction of a magnet 26a1 of a developing roller 26a, and a second developing side plate 26j1 that forms a developing side plate together with the first developing side plate 26k1, and rotatably holds a first conveying screw 26b1. The first developing side plate 26k1 is formed, at a position facing the second developing side plate 26j1, with an opening for a sheet 26k20 for causing a part of a sheet-like member 26r to project toward the outside of a developing device 26.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a developing device that develops a latent image formed on an image carrier such as a photosensitive drum, and to a process cartridge and an image forming apparatus that include the same. [Background technology]

[0002] Conventionally, in a developing device that is detachably installed in an image forming device such as a copier or printer, a technology has been known in which a sheet-like member (sealing member) is detachably provided to isolate the space containing the developer as a closed space so that the developer pre-stored inside the new developing device at the time of shipping from the factory does not leak out of the developing device during transportation, etc. (see, for example, Patent Document 1).

[0003] In detail, before the developing device is attached to the image forming apparatus main body and put into use, a sheet-like member is provided to separate the inside of the developing device so as to form a closed space containing the developer, and separate the developing roller from the first conveying screw (developer supply rotor) to prevent the developer pre-stored (preset) inside from leaking to the outside. Before use in the image forming apparatus main body begins, the sheet-like member is pulled out in the longitudinal direction (the direction corresponding to the rotational axis of the developing roller) from the opening (sheet opening) formed in the developing side plate, and the developer is accommodated entirely inside the developing device. In this way, the developing process (image formation) can be performed by the developing device. Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional technology, when the developer supply rotor or developing roller rotates during the development process, large vibrations are generated and transmitted to the development side plate, and even if the sheet opening is sealed with a sealing member such as a sponge, toner can leak out of the device from the sheet opening.

[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 that are less likely to cause the problem of toner leaking outside the device through the sheet opening formed in the developing side plate for removing the sheet-like member. [Means for solving the problem]

[0006] The developing device of this invention is a developing device that is detachably installed in the image forming apparatus main body and contains developer therein, and includes a developing roller that has a magnet with multiple magnetic poles formed in the circumferential direction installed therein and develops a latent image formed on the surface of an image carrier, a first developing side plate that has a magnet positioning portion formed thereon that determines the circumferential orientation of the magnet, a developer supply rotor that faces the developing roller and rotates in a predetermined direction to supply developer to the developing roller, and a second developing side plate that forms a developing side plate together with the first developing side plate and rotatably holds the developer supply rotor. The developing device is provided with a removable sheet-like member that separates the developing roller from the developer supply rotor to form a closed space in which the developer is contained inside the developer supply rotor side of the developing device so that the developer contained inside does not leak to the outside, and the first developing side plate is formed with a sheet opening at a position opposite the second developing side plate to allow a part of the sheet-like member to protrude toward the outside of the developing device. [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 that are less likely to experience the problem of toner leaking outside the device through the sheet opening formed in the developing side plate for removing the sheet-like member. [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] FIG. 2 is an enlarged view showing a main part of the developing device. [Figure 5] FIG. 2 is a top view showing the base portion of the upper developing case in the longitudinal direction. [Figure 6] FIG. 2 is a perspective view showing a part of the developing device with a sheet-like member attached thereto; [Figure 7] FIG. 2 is a perspective view showing a first developing device side plate. [Figure 8] (A) is a schematic front view showing the first and second developing side plates before the sheet-like member is removed, and (B) is a schematic front view showing the first and second developing side plates after the sheet-like member has been removed. [Figure 9] FIG. 10 is a perspective view showing a part of a developing device with a sheet-like member attached thereto, as a comparative example. [Figure 10] 10 is a perspective view showing a second developing side plate installed in the developing device of FIG. 9. FIG. [Figure 11] FIG. 10 is a schematic front view showing first and second developing device side plates according to a first modified example. [Figure 12] FIG. 10 is a diagram showing the positional relationship between a gear train and a sheet-like member in a developing device according to a second modified example. [Figure 13] FIG. 11 is an enlarged view showing a main part of a developing device according to a third modified example. 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 (printing).

[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 (transport screw) as a developer supply rotor facing the developing roller 26a, a second transport screw 26b2 facing the first transport screw 26b1 below via a partition member 26e, and a doctor blade 26c as a developer regulating member facing the developing roller 26a below and regulating the amount of developer carried on the developing roller 26a.

[0024] The developing device 26 contains a developer (a two-component developer containing additives and the like) made up of a carrier and a toner. In this embodiment, the average particle size of the toner is set to about 5.2 μm, the average particle size of the carrier is set to about 35 μm, the toner concentration is set to about 7 wt %, and the amount of developer in the developing device 26 is set to about 250 g.

[0025] The developing roller 26a is configured to face the photosensitive drum 21 with a small gap (developing gap) therebetween, thereby forming a developing area. As shown in Fig. 3, the developing roller 26a is composed of a magnet 26a1 that is fixedly installed inside the developing roller 26a and does not rotate, and has multiple magnetic poles H1 to H5 (see Fig. 4) formed in the circumferential direction, and a sleeve 26a2 that rotates around the magnet 26a1. The multiple magnetic poles H1 to H5 are formed on the outer circumferential surface of the developing roller 26a by the magnet 26a1.

[0026] 4, the drawing-up magnetic pole H5 (located at a position facing the doctor blade 26c (or near that position)) acts on the carrier as a magnetic body, drawing up the developer G accommodated in the first transport path B1 (see FIG. 2) onto the developing roller 26a. A portion of the developer G carried on the developing roller 26a is scraped off at the position of the doctor blade 26c (see FIG. 2) and returned to the first transport path B1. Meanwhile, at the position of the doctor blade 26c where the magnetic force of the drawing-up magnetic pole H5 acts, the developer G carried on the developing roller 26a passes through the doctor gap between the doctor blade 26c and the developing roller 26a, and stands up at the position of the main magnetic pole H1, becoming a magnetic brush in the development area and sliding against the photosensitive drum 21. In this way, the toner in the developer G carried on the developing roller 26a adheres to the latent image on the photosensitive drum 21. After that, the developer G that has passed the position of the main magnetic pole H1 is transported between the developer upper case 26k and the developer G by multiple transport magnetic poles H2 and H3, and then transported to the position of the developer releasing magnetic pole H4. Then, at the position of the developer releasing magnetic pole H4, a repulsive magnetic field (a magnetic field that acts in a direction away from the developing roller 26a) acts on the carrier, causing the developer G that has been carried on the developing roller 26a after the development process to be detached from the developing roller 26a. The detached developer G falls into the first transport path B1 and is transported downstream of the first transport path B1 by the first transport screw 26b1 (see FIGS. 2 and 3).

[0027] 2 and 3, the first and second transport screws 26b1 and 26b2 transport the developer G contained inside the developing device 26 in the longitudinal direction (direction of the rotation axis) to form a circulation path (the circulation path indicated by the dashed arrow in FIG. 3). That is, a circulation path for the developer is formed by the first transport path B1 formed by the first transport screw 26b1 and the 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 serving as a wall, and both longitudinal ends 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 ends.

[0028] The first transport screw 26b1 (first transport path B1) is disposed so as to face the developing roller 26a diagonally downward, and the second transport screw 26b2 (second transport path B2) is disposed so as to face the developing roller 26a below, with a partition member 26e (wall portion) interposed therebetween. The first transport screw 26b1 transports the developer in the rotation axis direction (longitudinal direction), while supplying the developer toward the developing roller 26a and recovering the post-development developer that has separated from the developing roller 26a. The second transport screw 26b2 stirs and mixes the post-development developer transported from the first transport path B1 with fresh toner supplied from a supply port 26d (see FIG. 3) while transporting them in the longitudinal direction. In this embodiment, the two conveying screws 26b1 and 26b2 are arranged side by side in the vertical direction. Each of the two conveying screws 26b1 and 26b2 has a rotation shaft portion 26b11 and a screw portion 26b12 and a screw portion 26b22 wound around the rotation shaft portion 26b11 and a screw portion 26b21 (shaft portion), and is driven to rotate at a rotation speed of about 600 rpm. In this way, by forming the circulation paths (first transport path B1 and second transport path B2) of developer G relative to developing roller 26a in the vertical direction instead of the horizontal direction, it is possible to reduce the horizontal size of developing device 26 (make it longer). In particular, in a tandem-type color image forming apparatus 1 in which multiple developing devices 26 (imaging units) are arranged side by side in the horizontal direction, it is possible to effectively reduce the overall horizontal size by reducing the horizontal size of the multiple developing devices 26 (imaging units).

[0029] 2, in this embodiment, the developing device 26 is provided with an upper developing case 26k and a lower developing case 26j as a developing case (housing). The lower developing case 26j rotatably holds the first and second transport screws 26b1 and 26b2, and also holds the doctor blade 26c. On the other hand, the upper developer case 26k is disposed so as to cover the lower developer case 26j (developing roller 26a). The upper developer case 26k rotatably holds the sleeve 26a2 (rotating shaft portion 26a2x) of the developing roller 26a, and non-rotatably holds the magnet 26a1 (non-rotating shaft portion 26a1x) of the developing roller 26a. The upper developer case 26k is configured to be detachable from the lower developer case 26j, which holds the conveying screws 26b1 and 26b2 and the doctor blade 26c, by snapping or screwing. In this embodiment, the upper developer case 26k holds the developing roller 26a, and the lower developer case 26j holds the transport screws 26b1 and 26b2 and the doctor blade 26c. However, the combination of components held by the upper developer case 26k and the lower developer case 26j is not limited to this. For example, the lower developer case 26j may be configured to hold the developing roller 26a, the transport screws 26b1 and 26b2, and the doctor blade 26c, and may be configured to be covered by the upper developer case 26k. In such a case, the first developing side plate 26k1, which will be described later, is held by the lower developer case 26j. In addition, the upper developer case 26k is integrally provided with a first developer side plate 26k1 (see Figures 6 to 8, etc.), and the lower developer case 26j is integrally provided with a second developer side plate 26j1 (see Figures 6, 8, etc.), which will be described in detail later.

[0030] The image forming process described above will now be further explained, focusing on the development process. Developing roller 26a rotates in a predetermined rotation direction (counterclockwise direction indicated by 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 toner supply port 26d via the toner supply path by rotation 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 the developer lift-up pole H5 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 development area). The toner is then attracted to the latent image formed on the photosensitive drum 21 by the electric field formed in the development 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 development area is formed by a predetermined voltage (development 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.

[0031] The toner in the toner container 70 is appropriately replenished into the developing device 26 from a replenishing port 26d (see FIG. 3) via a toner replenishing path (not shown) as the toner in the developing device 26 is consumed. The consumption of 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).

[0032] The configuration and operation of the developing device 26 (image forming apparatus 1), which is a feature of this embodiment, will be described in detail below. The developing device 26 in this embodiment is installed so as to be detachable (replaceable) from the image forming apparatus main body 1, and is replaced with a new one (including recycled products) at a predetermined replacement cycle. As previously explained using Figure 2 etc., the developing device 26 includes a developing roller 26a, a first transport screw 26b1 as a developer supply rotor, a second transport screw 26b2, etc., which are installed in a developing case (consisting of an upper developing case 26k and a lower developing case 26j). In addition, the developing device 26 is provided with a doctor blade 26c in the lower developing case 26j as a developer regulating member that faces the developing roller 26a, which is arranged diagonally above the first conveying screw 26b1 (developer supply rotor), from below and regulates the amount of developer G carried on the surface of the developing roller 26a.

[0033] Referring now to FIG. 4, the developing device 26 in this embodiment is provided with a sheet-like member 26r (removably configured) that separates the developing roller 26a and the first transport screw 26b1 (developer supply rotor) to form a closed space containing the developer G inside the developing device 26 on the side of the first transport screw 26b1 (the first and second transport paths B1 and B2) so that the developer G (which is 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 apparatus main body 1 begins.

[0034] Specifically, the sheet-like member 26r 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 in a substantially rectangular shape so as to extend in the direction of the rotation axis (the direction of the rotation axis of the developing roller 26a and the first and second transport screws 26b1 and 26b2, which is the left-right direction in FIG. 5). The sheet-like member 26r is attached (adhered) to the base portion 26j10 of the lower developing case 26j by double-sided tape, heat fusion, or the like so as to cover an opening 26j20 (see FIG. 5) formed in the base portion 26j10 so as to connect the space in which the developing roller 26a is installed with the space in which the first transport screw 26b1 is installed (first transport path B1). A new developing device 26 (including a recycled product) is shipped from a factory with the sheet-like member 26r installed, as shown in FIGS. 4 to 6. That is, at the factory, after the developer G is filled into the interior (first and second transport paths B1 and B2) of the developing device 26 after assembly into the developing lower case 26j, the sheet-like member 26r is attached to the base portion 26j1 of the developing lower case 26j so as to seal the first and second transport paths B1 and B2 to prevent the developer G from leaking. Finally, the developing upper case 26k is installed so as to cover the developing lower case 26j with the sheet-like member 26r set therein, completing the developing device 26 for shipment with the developer G preset therein.

[0035] 5 and 6, one end (part) of the sheet-like member 26r set in the developing device 26 in its longitudinal direction (the direction perpendicular to the plane of FIG. 4, that is, the left-right direction in FIG. 5) protrudes from the gap (sheet opening 26k20 (see FIG. 8)) between the upper developing case 26k (first developing side plate 26k1) and the lower developing case 26j (second developing side plate 26j1) to the outside of the developing device 26. When the user grips the protruding portion and pulls it out in the direction of the white arrow in FIG. 5, the opening 26j20 of the base portion 26j1 is opened, and the developing device 26 becomes usable.

[0036] Developing device 26 configured in this manner is mounted to image forming apparatus main body 1 with developer G contained therein and sealed by sheet-like member 26r, as shown in Fig. 4. 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, before the new developing device 26 is used (developing process) in the image forming apparatus 1, the sealed and sealed sheet-like member 26r is pulled out from the developing device 26. Then, the normal image forming process (developing process) is carried out in the state shown in FIG.

[0037] In this manner, in this embodiment, even when the developing device 26 is transported (carried) alone as a replacement, or even when the developing device 26 is transported attached to the image forming device main body 1 at the time of shipment, the developer G previously contained inside the developing device 26 is sealed by the sheet-like member 26r, thereby preventing the developer G contained inside from leaking outside the developing device 26 due to vibrations that occur during transportation, etc.

[0038] In particular, in this embodiment, as shown in FIG. 4, the sheet-like member 26r is installed inside the developing device 26 so as to separate the developing roller 26a and the first transport screw 26b1, thereby forming a closed space. This prevents developer G from being carried on the surface of developing roller 26a during transportation, thereby reliably preventing the user from touching the surface of developing roller 26a and becoming soiled with developer G. Furthermore, even when a new developing device 26 is installed in a new image forming apparatus main body 1 and shipped from the factory, it is possible to prevent the surface of the photosensitive drum from being damaged by developer G carried on the surface of developing roller 26a during transportation.

[0039] As shown in FIG. 4, in this embodiment, the doctor blade 26c (developer regulating member) is disposed below the developing roller 26a, which is disposed obliquely above the first transport screw 26b1. The base portion 26j10 is formed so that the downstream sheet attachment position 26j11 is located at a position lower than the top of the first conveying screw 26b1 (developer supply rotor), and the upstream sheet attachment position 26j12 is located at a position higher than the top Z. This configuration makes it easier to arrange the sheet-like member 26r so that it is perpendicular to the imaginary line connecting the rotation center of the developing roller 26a and the rotation center of the first transport screw 26b1. By arranging the sheet-like member 26r in this manner, the space between the developing roller 26a and the first transport screw 26b1 is efficiently partitioned, so that the opposing distance between the developing roller 26a and the first transport screw 26b1 can be set short, making it possible to reduce the size and weight of the developing device 26 and the amount of developer G for presetting.

[0040] Also, as shown in FIG. 5, in the developing device 26 of this embodiment, the widthwise range X2 of the sheet-like member 26r is set so as to be within the widthwise range X1 of the base portion 26j10 and to include the widthwise range X3 of the opening 26j20. In other words, when the width of the short side at the outer periphery of the base portion 26j10 is X1, the width of the short side of the opening 26j20 is X3, and the width of the short side of the sheet-like member 26r is X2, the relationship X1>X2>X3 holds. With this configuration, the opening 26j20 is reliably sealed by the sheet-like member 26r, and the sheet-like member 26r can be easily pulled out in the direction of the white arrow when starting to use the developing device 26.

[0041] 6 to 8, in the developing device 26 of the present embodiment, a first developing device side plate 26k1 and a second developing device side plate 26j1 are formed as developing device side plates on one end side of the developing device 26. In this embodiment, the second developing device side plate 26j1 is integrated with the lower developing device case 26j that rotatably holds the first conveying screw 26b1 and the second conveying screw 26b2. Further, a first developing device side plate 26k1 is integrated with an upper developing device case 26k that covers the developing roller 26a and constitutes a developing device case together with the lower developing device case 26j. As explained above, the first developing side plate 26k1 can be integrally formed with the second developing side plate 26j1 in the developing lower case 26j, and the developing roller 26a, the conveying screws 26b1, 26b2, and the doctor blade 26c can be held by the developing lower case 26j.

[0042] The first developing side plate 26k1 (upper developing plate) is formed with a D-shaped hole 26k10 as a magnet positioning portion that determines the circumferential orientation of the magnet 26a1 (see FIG. 3) of the developing roller 26a. The magnet 26a1 is a magnetic pole-forming member on which a plurality of magnetic poles H1 to H5 (see FIG. 5) are formed in the circumferential direction, and is provided inside the developing roller 26a (sleeve 26a2). The magnet 26a1 is held non-rotatingly in the developing device 26 by fitting a non-rotating shaft portion 26a1x (having a D-shaped cut portion formed at the end) on one end side into a D-shaped hole portion 26k10 (magnet positioning portion) of the first developing side plate 26k1. By holding the magnet 26a1 non-rotatingly in this manner, the desired magnetic poles H1 to H5 are formed on the developing roller 26a, which rotates in a predetermined direction during the developing process. In this way, since the first developing side plate 26k1 holds the non-rotating magnet 26a1 (non-rotating shaft portion 26a1x), vibrations caused by the operation of the developing device 26 during the developing process are less likely to be transmitted compared to a plate that holds a rotating shaft portion. On the other hand, the second developing side plate 26j1 (lower developing side plate) forms a developing side plate together with the first developing side plate 26k1, and rotatably holds the first transport screw 26b1 (developer supply rotor).

[0043] 6 to 8, the first developing side plate 26k1 has a sheet opening 26k20 formed at a position opposite the second developing side plate 26j1 to allow a portion (one end side) of the sheet-like member 26r to protrude toward the outside of the developing device 26. In detail, the sheet opening 26k20 is a concave cutout portion at a position opposite the second developing side plate 26j1, and its lower surface (the bottom surface of the first developing side plate 26k1) is approximately flush with the surface (upper surface) of the base portion 26j10.

[0044] Furthermore, the first developing device side plate 26k1 is provided with a sealing member 26w (sealing material) that seals the sheet opening 26k20 regardless of whether the sheet-like member 26r is removed or not. Specifically, the sealing member 26w is a substantially rectangular parallelepiped sealing material made of an elastic material such as polyurethane foam, and its upper surface is attached to the upper surface of the sheet opening 26k20 (the upper surface in Figure 8) via double-sided tape. The sealing member 26w is formed to be sufficiently larger than the size (particularly the size in the height direction) of the sheet opening 26k20, and seals the sheet opening 26k20 by elastically deforming. As shown in Figure 8(A), before the sheet-like member 26r is removed (when the sheet-like member 26r is set), the sealing member 26w attached to the sheet opening 26k20 of the first developing side plate 26k1 is pressed against the second developing side plate 26j1 so as to sandwich the sheet-like member 26r, thereby sealing the sheet opening 26k20 to prevent developer G from leaking out to the outside. Also, as shown in Figure 8(B), after the sheet-like member 26r is removed (when the sheet-like member 26r is pulled out), the sealing member 26w attached to the sheet opening 26k20 of the first developing side plate 26k1 is pressed directly against the second developing side plate 26j1, sealing the sheet opening 26k20 to prevent developer G from leaking out to the outside.

[0045] In this way, the developing device 26 in this embodiment has the sheet opening 26k20 formed in the first developing side plate 26k1, where vibrations are less likely to be transmitted during the developing process, so that the problem of developer G (especially toner) leaking out of the developing device 26 from the sheet opening 26k20 is less likely to occur compared to when the sheet opening is formed in a part of the developing side plate where vibrations are more likely to be transmitted during the developing process. In more detail, if a sheet opening 126j20 for pulling out the sheet-like member 126r is formed in the second developing side plate 126j1 of the developing lower case 126j as in the developing device 126 shown in Figures 9 and 10 as a comparative example, vibrations generated during the developing process (particularly vibrations caused by the rotation of the first conveying screw 26b1) will be directly transmitted to the second developing side plate 126, and even if the sheet opening 126j20 is sealed with a sealing member 126w, toner (developer G) will be likely to leak out of the developing device 26 from the sheet opening 126j20. In contrast, in this embodiment, the sheet opening 26k20 is formed in the first developing device side plate 26k1, to which vibrations are less likely to be transmitted, so that such a problem is less likely to occur.

[0046] Furthermore, by forming the sheet opening 26k20 in the first developer side plate 26k1, the position of the sheet opening 26k20 can be set higher, and the sheet opening 26k20 can be located above the boundary surface of the developer volume inside the developing device 26. If the joint between the developing case and the bearing (developer side plate) is located below the boundary surface of the developer volume (inside the developer G contained in the developing device 26) while the developing device 26 is in operation, there is a high possibility that the developer G will enter and leak through a minute gap formed there. Therefore, from this perspective, locating the sheet opening 26k20 above the boundary surface of the developer volume reduces the leakage of the developer G. Furthermore, when the sheet opening 26k20 is provided in the first developer side plate 26k1 or the second developer side plate 126j1, the complex shape that combines a cylindrical portion for fitting and positioning them with a flat portion for the sheet opening 26k20 results in low part precision. The same applies to the corresponding shape of the developer case to which it is fitted. For these reasons, in the past, extremely high precision was required for both the developer case and the bearings (mounted on the first developer side plate 26k1 or the second developer side plate 126j1) in terms of assembly ease (which tends to deteriorate if the tolerances are too tight) and developer G leakage resistance (which tends to deteriorate if the tolerances are too loose). This resulted in lower part yields and the need for careful production management, resulting in increased costs and part management issues. In contrast, in the developing device 26 of this embodiment, the sheet opening 26k20 is installed above the boundary surface of the developer volume, which makes it possible to relax tolerance management on the developer leakage side, making it less likely that the various problems described above will occur.

[0047] <Variation 1> As shown in FIG. 11, in the developing device 26 in the first modification, the first developing device side plate 26k1 and the second developing device side plate 26j1 are in contact with each other via a buffer member 26z such as a urethane sheet. By configuring it in this manner, vibrations of the second developing side plate 26j1 are less likely to be transmitted to the first developing side plate 26k1, making it even less likely that developer G (especially toner) will leak out of the developing device 26 through the sheet opening 26k20.

[0048] <Variation 2> 12, the developing device 26 in Modification 2 includes a first gear 91 mounted on a rotation shaft 26a2x (see FIG. 3) of the developing roller 26a, a second gear 92 mounted on a rotation shaft 26b11 (see FIG. 3) of the first transport screw 26b1 (developer supply rotor), a third gear 93 mounted on a rotation shaft 26b21 (see FIG. 3) of the second transport screw 26b2, and an idler gear 94 meshing with the first gear 91, the second gear 92, and the third gear 93, respectively, which are provided at one longitudinal end (drive side) of the developing device 26. A driving force is transmitted from a drive motor (not shown) to any of the first to third gears 91 to 93 and the idler gear 94, causing the developing roller 26a and the first and second transport screws 26b1 and 26b2 to rotate in respective predetermined directions. As shown in Figure 12, when viewed in a cross section perpendicular to the rotational axis direction (rotational shaft portions 26a2x, 26b11), the developing device 26 in variant example 2 has a sheet-like member 26r arranged in a space surrounded by the first gear 91, the second gear 92, and the idler gear 94. By configuring it in this manner, even if the sheet-like member 26r is configured to be pulled out from one longitudinal end side (drive side) of the developing device 26, problems such as the sheet-like member 26r interfering with the first gear 91, the second gear 92, or the idler gear 94 are less likely to occur. In particular, in variant example 2, the outer diameter (tooth tip circle diameter) of the idler gear 94 is configured to be smaller than the outer diameter (tooth tip circle diameter) of the first gear 91 and smaller than the outer diameter (tooth tip circle diameter) of the second gear 92.Therefore, in the space surrounded by the first gear 91, the second gear 92, and the idler gear 94, the width of the sheet-like member 26r in the short direction can be secured relatively wide, and it is also easier to secure the opening width of the opening 26j20 in the base portion 26j10 in the short direction.

[0049] <Variation 3> As shown in FIG. 13, the developing device 26 in the third modified example also has a base portion 26j1 formed on the developing lower case 26j. Here, in the developing device 26 in variant example 3, the base portion 26j10 is not integrally formed as part of the developing lower case 26j, but rather the base portion 26j10 is a separate part that is attached (glued) to the developing lower case 26j via double-sided tape, adhesive, etc. An opening 26j20 is formed in the base 26j10, and a sheet-like member 26r is placed on the base 26j10 so as to cover the opening 26j20. When use of the developing device 26 begins, the sheet-like member 26r is pulled out from the base 26j10. The base 26j10 continues to function as a part of the developing lower case 26j even after use of the developing device 26 begins. By configuring the base portion 26j10 to be installed as a separate part in the lower developing case 26j in this manner, it becomes possible to form the base portion 26j10 from a material to which the sheet-like member 26r can be easily heat-sealed or attached with double-sided tape, for example, when the lower developing case 26j is formed from a material to which the sheet-like member 26r is difficult to heat-seal or attach with double-sided tape.

[0050] As described above, developing device 26 in this embodiment is a developing device that is detachably installed in image forming apparatus main body 1 and contains developer G. It includes: developing roller 26a, which has magnet 26a1 with multiple magnetic poles H1 to H5 formed circumferentially therein and develops a latent image formed on the surface of photosensitive drum 21 (image carrier); and first transport screw 26b1 (developer supply rotor) that rotates in a predetermined direction opposite developing roller 26a to supply developer G to developing roller 26a. Furthermore, to prevent developer G contained inside developing device 26 from leaking out, a removable sheet-like member 26r is provided that separates developing roller 26a and first transport screw 26b1, forming a closed space containing developer G inside developing device 26 on the side of first transport screw 26b1. Further provided are a first developing device side plate 26k1 having a D-shaped hole 26k10 (magnet positioning portion) for determining the circumferential orientation of the magnet 26a1, and a second developing device side plate 26j1 that forms a developing device side plate together with the first developing device side plate 26k1 and rotatably holds the first conveying screw 26b1. The first developing device side plate 26k1 has a sheet opening 26k20 formed at a position facing the second developing device side plate 26j1, for allowing a part of the sheet-like member 26r to protrude toward the outside of the developing device 26. This reduces the risk of toner leaking out of the device through the sheet opening 26k20 formed in the developing side plates 26k1 and 26j1 for removing the sheet-like member 26r.

[0051] 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.

[0052] 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 the developing device 26 in which a transport screw (first transport screw 26b1) having a screw portion 26b12 wound around a rotation shaft portion 26b11 is installed as the developer supply rotor. However, the developer supply rotor is not limited to this, and the present invention can also be applied to, for example, a developing device in which a transport paddle having a plurality of blade portions formed radially in the circumferential direction on a rotation shaft portion is installed as the developer supply rotor. In such cases, the same effect as that of this embodiment can be obtained.

[0053] 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]

[0054] 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), 26a1 magnet, 26a1x Non-rotating shaft part, 26a2 sleeve, 26a2x Rotating shaft, 26b1 first conveying screw (developer supply rotor), 26b11 Rotating shaft part, 26b12 screw section, 26b2 second conveying screw, 26c Doctor blade (developer control member), 26j developing case (developing case), 26j1 Second developing side panel (developing side panel), 26k developing case (developing case), 26k1 First developing side plate (developing side plate), 26k10 D-hole (magnet positioning part), 26k20 Seat opening, 26r Sheet-shaped material (sealing material), 26w sealing member, 26z buffer material, 91 1st gear, 92 2nd gear, 94 idler gear, B1 First transport route (transport route), B2 Second transport route, G Developer (two-component developer).

[0055] The present invention can also be embodied in a combination of Supplementary Notes 1 to 10, for example, as follows. (Appendix 1) A developing device that is detachably installed in the image forming apparatus main body and contains a developer therein, a developing roller having a magnet with a plurality of magnetic poles formed in a circumferential direction therein, for developing a latent image formed on the surface of the image carrier; a first developing side plate having a magnet positioning portion formed thereon that determines the circumferential orientation of the magnet; a developer supplying rotor that faces the developing roller and rotates in a predetermined direction to supply developer to the developing roller; a second developing side plate that forms a developing side plate together with the first developing side plate and rotatably holds the developer supply rotor; a removable sheet-like member that separates the developing roller from the developer supply rotor to prevent the developer contained in the developing device from leaking to the outside, and forms a closed space in which the developer is contained inside the developing device on the developer supply rotor side; Equipped with A developing device characterized in that the first developing side plate has a sheet opening formed at a position opposite the second developing side plate to allow a portion of the sheet-like member to protrude toward the outside of the developing device. (Appendix 2) 2. The developing device according to claim 1, wherein the first developing side plate is provided with a sealing member that seals the sheet opening regardless of whether the sheet-like member is removed or not. (Appendix 3) The developing device according to claim 1 or 2, wherein the sheet opening is a cutout portion at a position facing the second developing side plate. (Appendix 4) 4. The developing device according to any one of claims 1 to 3, wherein the first developing device side plate and the second developing device side plate are in contact with each other via a buffer member. (Appendix 5) The developer supply rotor is a first transport screw having a screw portion wound around a rotation shaft portion and capable of transporting the developer in the rotation shaft direction, The developing device according to any one of Supplementary Note 1 to Supplementary Note 4, further comprising a second transport screw that faces the first transport screw below with a wall portion interposed therebetween and forms a circulation path for developer together with the first transport screw. (Appendix 6) a lower developing case that rotatably holds the first conveying screw and the second conveying screw, and that is integrated with at least the second developing side plate of the first developing side plate and the second developing side plate; an upper developer case that covers the developing roller and constitutes a developing case together with the lower developer case; 6. The developing device according to claim 5, comprising: (Appendix 7) a first gear provided on a rotation shaft portion of the developing roller, a second gear provided on a rotation shaft portion of the developer supply rotor, and idler gears meshing with the first gear and the second gear, A developing device according to any one of appendices 1 to 6, characterized in that the sheet-like member is arranged in a space surrounded by the first gear, the second gear, and the idler gear when viewed in a cross section perpendicular to the rotational shaft portion of the developing roller or the developer supply rotor. (Appendix 8) 8. The developing device according to claim 7, wherein the idler gear has an outer diameter smaller than that of the first gear and smaller than that of the second gear. (Appendix 9) a process cartridge detachably installed in the image forming apparatus main body, A process cartridge comprising the developing device according to any one of claims 1 to 8 and the image carrier, the process cartridge being integrally provided with the developing device. (Appendix 10) An image forming apparatus comprising the developing device according to any one of Supplementary Notes 1 to 8. [Prior art documents] [Patent documents]

[0056] [Patent Document 1] Patent No. 4764766

Claims

1. A developing device that is detachably installed in the image forming apparatus main body and contains a developer therein, a developing roller having a magnet with a plurality of magnetic poles formed in a circumferential direction therein, for developing a latent image formed on the surface of the image carrier; a first developing side plate having a magnet positioning portion formed thereon that determines the circumferential orientation of the magnet; a developer supplying rotor that faces the developing roller and rotates in a predetermined direction to supply developer to the developing roller; a second developing side plate that forms a developing side plate together with the first developing side plate and rotatably holds the developer supply rotor; a removable sheet-like member that separates the developing roller from the developer supply rotor to prevent the developer contained in the developing device from leaking to the outside, and forms a closed space in which the developer is contained inside the developing device on the developer supply rotor side; Equipped with A developing device characterized in that the first developing side plate has a sheet opening formed at a position opposite the second developing side plate to allow a portion of the sheet-like member to protrude toward the outside of the developing device.

2. 2. The developing device according to claim 1, wherein the first developing side plate is provided with a sealing member that seals the sheet opening regardless of whether the sheet member is removed or not.

3. 3. The developing device according to claim 1, wherein the sheet opening is a cutout portion at a position facing the second developing side plate.

4. 3. The developing device according to claim 1, wherein the first developing side plate and the second developing side plate are in contact with each other via a buffer member.

5. the developer supply rotor is a first transport screw having a screw portion wound around a rotation shaft portion and capable of transporting the developer in the rotation shaft direction, 3. The developing device according to claim 1, further comprising a second transport screw that faces the first transport screw below with a wall portion interposed therebetween and forms a circulation path for the developer together with the first transport screw.

6. a lower developing case that rotatably holds the first conveying screw and the second conveying screw, and that is integrated with at least the second developing side plate of the first developing side plate and the second developing side plate; an upper developer case that covers the developing roller and constitutes a developing case together with the lower developer case; 6. The developing device according to claim 5, further comprising:

7. a first gear provided on a rotation shaft portion of the developing roller, a second gear provided on a rotation shaft portion of the developer supply rotor, and idler gears meshing with the first gear and the second gear, 3. The developing device according to claim 1, wherein the sheet-like member is arranged in a space surrounded by the first gear, the second gear, and the idler gear when viewed in a cross section perpendicular to the rotational shaft portion of the developing roller or the developer supply rotor.

8. 8. The developing device according to claim 7, wherein the outer diameter of the idler gear is smaller than the outer diameter of the first gear and smaller than the outer diameter of the second gear.

9. a process cartridge detachably installed in the image forming apparatus main body, 3. A process cartridge comprising the developing device according to claim 1 or 2 and the image carrier, the developing device and the image carrier being integrally provided.

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

Images