Developing device, process cartridge, and image forming apparatus

Abstract

To easily install a sheet-like member to partition a developing roller and a developer supply rotating body from each other.SOLUTION: A developing device is provided with a removable sheet-like member 26r that partitions a developing roller 26a and a first conveying screw 26b1 from each other. A developing upper case 26k covering the developing roller 26a is arranged above the sheet-like member 26r, and a developing lower case 26j constituting a developing case together with the developing upper case 26k is arranged below the sheet-like member 26r. When seen on a cross section orthogonal to a rotation axis direction of the developing roller 26a, the developing lower case 26j is divided into two, which are a first developing lower case 26j1 and a second developing lower case 26j2, and the sheet-like member 26r is directly or indirectly removably installed so as to extend over the first developing lower case 26j1 and the second developing lower case 26j2.SELECTED DRAWING: Figure 4

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 the conventional technology, it was difficult to install a sheet-like member to separate the developing roller and the developer supplying rotor during the assembly process of the developing device.

[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 a sheet-like member can be easily installed to separate the developing roller and the developer supply rotor. [Means for solving the problem]

[0006] The developing device of this invention is a developing device that is detachably installed in the image forming device main body and contains developer inside, and comprises a developing roller that develops a latent image formed on the surface of an image carrier, a developer supply rotor that faces the developing roller and rotates in a predetermined direction to supply developer to the developing roller, a removable sheet-like member that separates the developing roller and the developer supply rotor and forms a developer pre-storage section in which developer is contained inside the developer supply rotor side of the developing device, an upper developing case that is arranged above the sheet-like member and covers the developing roller, and a lower developing case that is arranged below the sheet-like member and forms a developing case together with the upper developing case, and when viewed in a cross section perpendicular to the rotational axis direction of the developing roller, the lower developing case is divided into two, a first lower developing case and a second lower developing case, and the sheet-like member is installed so as to be directly or indirectly detachable so as to straddle the first lower developing case and the second lower developing case. [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 apparatus in which a sheet-like member can be easily installed to separate the developing roller and the developer supply rotor. [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. 4 is an enlarged view showing the vicinity of the joint between the first and second lower developing cases. [Figure 7] FIG. 4 is an enlarged view showing a main part of a developing device as a comparative example. [Figure 8] 10A and 10B are diagrams illustrating a positional relationship between a gear train and a sheet-like member in a developing device as a 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 23a and a cleaning roller 23b that come into contact with the photosensitive drum 21. The cleaning blade 23a 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 23b 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, and the toner concentration is set to about 7 wt %.

[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). 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 developing lower case 26j rotatably holds the first and second conveying screws 26b1 and 26b2, and also holds the doctor blade 26c. The developing lower case 26j also 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. On the other hand, the upper developer case 26k is placed on top of the lower developer case 26j and is arranged to cover the lower developer case 26j (developing roller 26a). The upper developer case 26k is configured to be detachable from the lower developer case 26j, which holds the developing roller 26a, the conveying screws 26b1 and 26b2, and the doctor blade 26c, by snapping or screwing. The developing lower case 26j is configured to be separable into a first developing lower case 26j1 and a second developing lower case 26j2, 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 developer pre-storage section (almost a closed space) in which the developer G is stored inside the developing device 26 on the side of the first transport screw 26b1 (the first and second transport paths B1 and B2) in the developing device 26, so that the developer G stored inside the developing device 26 (the developer G is pre-filled at the time of shipment from the factory) does not leak out until use in the image forming apparatus main body 1 begins.

[0034] Specifically, the sheet-like member 26r is a flexible member made of a transparent resin material such as an OHP sheet or Mylar, having a thickness of approximately 0.1 to 0.5 mm. The flexible sheet-like member 26r is formed in a substantially rectangular shape so as to extend in the rotational axis direction (the rotational axis direction 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 a base portion 26j10 (which is installed and fixed as a separate component in this embodiment) installed in the lower developing case 26j so as to cover an opening 26j20 (see FIG. 5) formed in the base portion 26j10, which is installed and fixed as a separate component, in order to communicate 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 recycled products) is shipped from a factory with the sheet-like member 26r installed, as shown in FIG. 4. That is, at the factory, after developer G is filled into the interior (first and second transport paths B1 and B2) of the developing device 26 that has been completely assembled 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. In the present embodiment, the developing device 26 is assembled in a factory after the developer G is filled inside the developing device 26 in a state where assembly into the developing device lower case 26j is completed, and then the sheet-like member 26r is attached to the base portion 26j1 of the developing device lower case 26j, and then the developing device upper case 26k is installed. However, the assembly procedure is not limited to this. For example, the developing device 26 may be assembled in a state where assembly into the developing device lower case 26j is completed, and then the sheet-like member 26r is attached to the base portion 26j1 of the developing device lower case 26j, and then the developing device upper case 26k is installed, and finally the developer G is filled inside the developing device 26 after assembly is completed.

[0035] 5, 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, the left-right direction in FIG. 5) protrudes from the gap between the upper developer case 26k and the lower developer case 26j to the outside of the developing device 26. When the user grasps 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 26j21 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 Figure 4, in this embodiment, the doctor blade 26c (developer regulating member) is set so that the position of its tip (upper end) facing the developing roller 26a is higher than the downstream sheet attachment position 26j11 and lower than the upstream sheet attachment position 26j21. With this configuration, it is easy to arrange the sheet member 26r so that it is perpendicular to the imaginary line S connecting the rotation center of the developing roller 26a and the rotation center of the first conveying screw 26b1, while maintaining the function of the doctor blade 26c well.

[0041] 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. By configuring it in this manner, the opening 26j20 is reliably sealed by the sheet-like member 26r, and when starting to use the developing device 26 (when pulling out the sheet-like member 26r), the sheet-like member 26r is less likely to twist or get caught, making it easier to pull out the sheet-like member 26r in the direction of the white arrow.

[0042] As previously described with reference to FIG. 4 and the like, the developing device 26 in this embodiment is provided with an upper developing case 26k and a lower developing case 26j. The upper developer case 26k is disposed generally above the sheet-like member 26r so as to cover the developing roller 26a. On the other hand, the lower developer case 26j is disposed generally below the sheet-like member 26r and constitutes a developer case together with the upper developer case 26k.

[0043] Here, as shown in Figure 4, in this embodiment, the developing lower case 26j is divided into two parts, a first developing lower case 26j1 and a second developing lower case 26j2, when viewed in a cross section perpendicular to the rotational axis direction of the developing roller 26a. That is, the developing case is divided into three parts: an upper developing case 26k, a first lower developing case 26j1, and a second lower developing case 26j2. In the lower developing case 26j, a sheet-like member 26r is directly or indirectly removably disposed across the first lower developing case 26j1 and the second lower developing case 26j2.

[0044] More specifically, in this embodiment, the sheet-like member 26r is indirectly and detachably installed via a pedestal 26j10 (pedestal member) so as to straddle the first developing lower case 26j1 and the second developing lower case 26j2. The pedestal 26j10 is attached (bonded) to the developing lower case 26j as a separate part using double-sided tape, adhesive, or the like. As described above, in this embodiment, the sheet-like member 26r is not directly attached (adhered) across the first and second developing lower cases 26j1 and 26j2, but is indirectly attached (adhered) across the first and second developing lower cases 26j1 and 26j2 via the base 26j10. This increases the flexibility in selecting a material for the base 26j10 (allowing for the selection of a material that is compatible with the sheet-like member 26r), thereby improving the attachment (adhesion) of the sheet-like member 26r. Furthermore, even if there is a step or gap at the joint between the first and second developing lower cases 26j1 and 26j2, the sheet-like member 26r can ensure sealing. In this embodiment, the base portion 26j10 is installed as a separate part on the lower developing case 26j, but if the problems described above (such as materials, steps, gaps, etc.) can be resolved, the sheet-like member 26r may be directly attached (glued) to the lower developing case 26j.

[0045] More specifically, in this embodiment, as shown in Figure 4, when viewed in a cross section perpendicular to the rotational axis direction of the developing roller 26a, the developing lower case 26j is divided at approximately the center of the developing lower case 26j into a first developing lower case 26j1 arranged on the side corresponding to the downstream side in the rotational direction of the developing roller 26a (the right side in Figure 4), and a second developing lower case 26j2 arranged on the side corresponding to the upstream side in the rotational direction of the developing roller 26a (the left side in Figure 4).

[0046] In particular, the developing roller 26a, the first and second transport screws 26b1 and 26b2, and the doctor blade 26c are installed in the first developing lower case 26j1. In the process of assembling the developing lower case 26j, the second developing lower case 26j2 is detachably attached to the first developing lower case 26j1, in which the first and second transport screws 26b1 and 26b2, and the doctor blade 26c are installed, by snapping or screwing from the lateral direction in FIG. 4. This facilitates the assembly of the developing roller 26a, the first and second transport screws 26b1 and 26b2, and the doctor blade 26c in the developing lower case 26j. Then, the developer G for presetting is stored in the developer pre-storage section (first and second transport paths B1, B2) of the developing lower case 26j assembled in this manner, and then the base section 26j10 to which the sheet-like member 26r is attached is placed. Finally, the upper developer case 26k is placed on the lower developer case 26j in this state, completing the developing device 26 in its shipping state. As explained above, the assembly procedure of the developing device 26 at the time of shipment is not limited to this, and the developer G may be finally filled into the inside of the developing device 26 after the assembly of the developing roller 26a, the conveying screws 26b1, 26b2, the doctor blade 26c, the sheet-like member 26r, the developing upper case 26k, etc. into the developing lower case 26j is completed.

[0047] In this way, in the developing device 26 of this embodiment, compared to the developing device 126 shown as a comparative example in Figure 7 in which the developing cases 126k and 126j are divided into two, it is easier to install the sheet-like member 26r to separate the developing roller 26a and the first conveying screw 26b1 (developer supply rotor) during the assembly process of the developing device 26. 7 as a comparative example is configured to combine a first developing case 126k formed to cover the developing roller 26a from above to the sides (rear) of the first and second transport paths B1 and B2 with a second developing case 126j (in which the developing roller 26a, first and second transport screws 26b1 and 26b2, and doctor blade 26c are installed) formed to cover the sides (front) of the first and second transport paths B1 and B2. Therefore, the sheet-like member 26r (base portion 26j10) must be installed so as to be inserted between the developing roller 26a and the first transport screw 26b1, making the installation work difficult. In contrast to this, in this embodiment, as explained above, the work of storing developer G in the developer pre-storage section of the developing lower case 26j and then the work of placing the sheet-like member 26r (base portion 26j10) on the developing lower case 26j to seal the developer pre-storage section can be performed smoothly.

[0048] Referring to FIG. 6, in this embodiment, a joint 26jx between the first developing lower case 26j1 and the second developing lower case 26j2 is formed in a nested manner. Therefore, compared to a joint made up of two flat surfaces, the problem of developer G leaking from the joint 26jx between the first developing lower case 26j1 and the second developing lower case 26j2 can be reduced. In particular, in this embodiment, joint 26jx is formed so that upper end 26jx1 of the lower fitting portion is positioned at a predetermined height δ higher than lower end 26jx2 of the upper fitted portion. By configuring in this manner, even if developer G gets into the joint 26jx, the developer G that has gotten in will tend to accumulate and clog the joint 26jx, further reducing the problem of developer G leaking from the joint 26jx.

[0049] Referring to Figure 4, the first developing lower case 26j1 and the second developing lower case 26j2 are formed so that when viewed in a cross section perpendicular to the rotational axis direction of the first transport screw 26b1 (or the second transport screw 26b2), the bottom of the first transport path B1 by the first transport screw 26b1 and the bottom of the second transport path B2 by the second transport screw 26b2 are each arc-shaped (arcs that are approximately concentric with the screw diameter). With this configuration, dead spaces where the developer G is likely to stagnate are less likely to occur in the first and second transport paths B1 and B2 along which the developer G is transported.

[0050] <Modification> 8, the developing device 26 in the modified example 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 8, when viewed in a cross section perpendicular to the rotational axis direction (rotational shaft portions 26a2x, 26b11), the developing device 26 in the modified example has a portion of the sheet-like member 26r arranged in the 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 the modified example, 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 in the short direction of the opening 26j20 in the base portion 26j10.

[0051] As described above, the developing device 26 in this embodiment is a developing device that is detachably installed in the image forming apparatus main body 1 and contains developer G. The developing device 26 includes a developing roller 26a that develops a latent image formed on the surface of the photosensitive drum 21 (image carrier), and a first transport screw 26b1 (developer supply rotor) that rotates in a predetermined direction opposite the developing roller 26a to supply developer G to the developing roller 26a. A removable sheet-like member 26r is also provided to separate the developing roller 26a from the first transport screw 26b1 and form a developer pre-container (closed space) containing developer G inside the developing device 26 on the side of the first transport screw 26b1. An upper developer case 26k that covers the developing roller 26a is disposed above the sheet-like member 26r, and a lower developer case 26j that, together with the upper developer case 26k, forms a developing case is disposed below the sheet-like member 26r. When viewed in a cross section perpendicular to the rotational axis of the developing roller 26a, the developing lower case 26j is divided into two parts, a first developing lower case 26j1 and a second developing lower case 26j2, and a sheet-like member 26r is installed directly or indirectly so as to be removable and straddle the first developing lower case 26j1 and the second developing lower case 26j2. This makes it possible to easily install the sheet-like member 26r so as to separate the developing roller 26a and the first transport screw 26b1 (developer supply rotary member).

[0052] 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.

[0053] 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.

[0054] 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]

[0055] 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), 26b1 first conveying screw (developer supply rotor), 26b2 second conveying screw, 26c Doctor blade (developer control member), 26j developing case (developing case), 26j1 First developing case (developing case), 26j2 Second developing case (developing case), 26jx joint, 26jx1 upper end, 26jx2 lower end, 26j10 Base part (base member), 26k developing case (developing case), 26r Sheet-shaped material (sealing 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).

[0056] 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 for developing a latent image formed on the surface of the image carrier; a developer supplying rotor that faces the developing roller and rotates in a predetermined direction to supply developer to the developing roller; a removable sheet-like member that separates the developing roller from the developer supply rotor and forms a developer pre-accommodating section in which developer is accommodated inside the developing device on the developer supply rotor side; an upper developing case disposed above the sheet-like member and covering the developing roller; a lower developer case disposed below the sheet-like member and constituting a developer case together with the upper developer case; Equipped with The developing device is characterized in that, when viewed in a cross section perpendicular to the rotational axis direction of the developing roller, the developing lower case is divided into two, a first developing lower case and a second developing lower case, and the sheet-like member is directly or indirectly installed so as to straddle the first developing lower case and the second developing lower case. (Appendix 2) The developing device described in Appendix 1, characterized in that when viewed in a cross section perpendicular to the rotational axis of the developing roller, the developing lower case is divided at approximately the center of the developing lower case into the first developing lower case arranged on the side corresponding to the downstream side of the rotational direction of the developing roller, and the second developing lower case arranged on the side corresponding to the upstream side of the rotational direction of the developing roller. (Appendix 3) The developing device according to claim 1 or 2, wherein the joint between the first developing lower case and the second developing lower case is formed in a nested manner. (Appendix 4) 4. The developing device according to claim 3, wherein the joint is formed so that the upper end of the lower engaging portion is higher than the lower end of the upper engaged portion. (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, 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; The developing device described in any one of Appendix 1 to Appendix 4, characterized in that the first developing lower case and the second developing lower case are formed so that, when viewed in a cross section perpendicular to the rotational axis direction of the first transport screw or the second transport screw, the bottom of the first transport path formed by the first transport screw and the bottom of the second transport path formed by the second transport screw are each arc-shaped. (Appendix 6) The developing device described in any one of Appendix 1 to Appendix 5, characterized in that the sheet-like member is removably installed via a base portion so as to straddle the first developing lower case and the second developing lower case. (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 Appendix 1 to Appendix 6, characterized in that, when viewed in a cross section perpendicular to the rotational shaft portion of the developing roller or the developer supply rotor, a portion of the sheet-like member is arranged in a space surrounded by the first gear, the second gear, and the idler gear. (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]

[0057] [Patent Document 1] Japanese Patent Application Publication No. 2023-142274

Claims

1. A developing device that is detachably installed in the image forming apparatus main body and contains a developer therein, a developing roller for developing a latent image formed on the surface of the image carrier; a developer supplying rotor that faces the developing roller and rotates in a predetermined direction to supply developer to the developing roller; a removable sheet-like member that separates the developing roller from the developer supply rotor and forms a developer pre-accommodating section in which developer is accommodated inside the developing device on the developer supply rotor side; an upper developing case disposed above the sheet-like member and covering the developing roller; a lower developer case disposed below the sheet-like member and constituting a developer case together with the upper developer case; Equipped with A developing device characterized in that, when viewed in a cross section perpendicular to the rotational axis direction of the developing roller, the developing lower case is divided into two, a first developing lower case and a second developing lower case, and the sheet-like member is directly or indirectly installed so as to straddle the first developing lower case and the second developing lower case.

2. The developing device according to claim 1, characterized in that, when viewed in a cross section perpendicular to the rotational axis of the developing roller, the developing lower case is divided at approximately the center of the developing lower case into the first developing lower case arranged on the side corresponding to the downstream side of the rotational direction of the developing roller, and the second developing lower case arranged on the side corresponding to the upstream side of the rotational direction of the developing roller.

3. 3. The developing device according to claim 1, wherein a joint between the first and second developing lower cases is formed in a nested manner.

4. 4. The developing device according to claim 3, wherein the joint is formed so that an upper end of the lower engaging portion is positioned higher than a lower end of the upper engaged portion.

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, 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; The developing device according to claim 1 or claim 2, characterized in that the first developing lower case and the second developing lower case are formed so that, when viewed in a cross section perpendicular to the rotational axis direction of the first transport screw or the second transport screw, the bottom of the first transport path formed by the first transport screw and the bottom of the second transport path formed by the second transport screw are each arc-shaped.

6. 3. The developing device according to claim 1, wherein the sheet-like member is removably installed via a base portion so as to straddle the first developing lower case and the second developing lower case.

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 a portion of 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