Developer storage device, developing device, process cartridge, and image forming apparatus

Abstract

To sufficiently dissipate heat that is generated due to slide contact of seal members with a rotation shaft of rotating members, thereby increasing processability.SOLUTION: A developing device 26 (developer storage device) storing developer is provided with conveying screws 26b1, 26b2 (rotating members) that are provided with a rotation shaft 261, bearings 26m that are formed of a metal material and rotatably hold the rotation shaft 261, holding members 26n that each have an inner diameter part 26n1 to which the bearing 26m is press fit, and seal members 26t that each are in slide contact with an outer peripheral surface of the rotation shaft 261 at a position inside the developing device 26 with respect to the bearing 26m. The seal members 26t are each in contact with an inside end face of the bearing 26m at the inner diameter part 26n1 of the holding member 26n.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a developer storage device that stores a developer such as a toner or a two-component developer, a developing device, a process cartridge, and an image forming apparatus. [Background technology]

[0002] Conventionally, a technology has been known in which a sealing member (toner seal) is installed on a bearing that holds a rotating member (conveying screw) in a developer storage device (developing device) installed in an image forming device such as a copier or printer (see, for example, Patent Document 1).

[0003] On the other hand, Patent Document 1 discloses a technology in which a metal plate is embedded between the inner and outer parts of the bearing and a toner seal (sealing member) is brought into contact with the metal plate in order to suppress temperature rise in the bearing seal portion. Summary of the Invention [Problem to be solved by the invention]

[0004] The technology of Patent Document 1 mentioned above embeds a metal plate between the inner and outer parts of the bearing and brings a sealing member into contact with the metal plate, so that it is expected that the heat generated by the sealing member sliding against the rotating shaft of the rotating member will be dissipated to a certain extent via the metal plate. However, in the technology of Patent Document 1, the volume of the metal plate embedded in the bearing is small, and the heat dissipation performance is insufficient, and the workability when embedding the metal plate in the bearing is low.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a developer storage device, a developing device, a process cartridge, and an image forming apparatus that are highly processable and in which heat generated by the sealing member sliding against the rotating shaft of the rotating member is sufficiently dissipated. [Means for solving the problem]

[0006] The developer storage device of the present invention is a developer storage device in which developer is stored, and includes a rotating member having a rotating shaft, and a metal member that rotatably holds the rotating shaft. ball bearing and, Without contacting the rotating shaft, The aforementioned ball bearing a holding member press-fitted into an inner diameter portion thereof; ball bearing a seal member that is in sliding contact with the outer circumferential surface of the rotary shaft at a position inside the developer accommodating device with respect to the rotary shaft, and the seal member is A flexible sheet member, the base portion of which comprises: At the inner diameter portion of the holding member 、 The aforementioned ball bearing the inner end surface of and the opposing surface of the holding member that faces the end surface, and is supported as a cantilever, and the tip end portion thereof is in sliding contact with the outer circumferential surface of the rotating shaft at the inner diameter portion. It is something. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a developer storage device, a developing device, a process cartridge, and an image forming device that are highly processable, in which heat generated by the sealing member sliding against the rotating shaft of the rotating member is sufficiently dissipated. [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. 3 is a cross-sectional view showing the vicinity of a bearing that supports a conveying screw. [Figure 5] 10 is a cross-sectional view showing the vicinity of a bearing that supports a conveying screw in a developing device according to a first modified example. FIG. [Figure 6] 10 is a cross-sectional view showing the vicinity of a bearing that supports a conveying screw in a developing device according to a second modified example. FIG. [Figure 7] 10 is a graph showing the relationship between the driving time of the developing device and the temperature rise in the vicinity of the seal member. 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) serving as a developer containing device is provided 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, 66 denotes a fixing device that fixes the unfixed image on the sheet P, and 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.

[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. Each of the process cartridges 20Y, 20M, 20C, and 20BK is replaced with a new one in the image forming apparatus main body 1 when it reaches the end of its life. 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 replaced with a new one in the image forming apparatus main body 1. 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 (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). 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, and the untransferred toner on the intermediate transfer belt 40 is collected by the intermediate transfer belt cleaning device, completing the series of transfer processes on the intermediate transfer belt 40.

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

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

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

[0022] As shown in FIG. 2, the process cartridge 20 mainly includes a photosensitive drum 21 as an image carrier, a charging device 22, and a cleaning device 23 housed integrally in a case. The 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 as a developer storage device is mainly composed of a developing roller 26a as a developer carrier, a first transport screw 26b1 (first transport member) facing the developing roller 26a, a second transport screw 26b2 (second transport member) as a rotating member facing the first transport screw 26b1 via a partition member 26e, and a doctor blade 26c (developer regulating member) facing the developing roller 26a to regulate the amount of developer carried on the developing roller 26a.

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

[0025] The transport screws 26b1 and 26b2 as screw members transport the developer contained inside the developing device 26 in the longitudinal direction to form a circulation path (the circulation path indicated by the dashed arrow in FIG. 3). That is, a developer circulation path is formed by a first transport path B1 formed by the first transport screw 26b1 and a second transport path B2 formed by the second transport screw 26b2. The first transport path B1 and the second transport path B2 are separated by a partition member 26e (wall portion), and both longitudinal end portions of the two transport paths B1 and B2 communicate with each other via communication openings 26f and 26g. Specifically, referring to FIG. 3, the upstream end of the first transport path B1 in the transport direction communicates with the downstream end of the second transport path B2 in the transport direction via the first communication opening 26f. Furthermore, the downstream end of the first transport path B1 in the transport direction communicates with the upstream end of the second transport path B2 in the transport direction via the second communication opening 26g. In other words, the partition member 26e is disposed at a position excluding both longitudinal end portions. The first transport screw 26b1 (first transport path B1) is disposed opposite the developing roller 26a, and the second transport screw 26b2 (second transport path B2) is disposed opposite the first transport screw 26b1 (first transport path B1) via a partition member 26e. The first transport screw 26b1 transports the developer in the longitudinal direction while supplying the developer toward the developing roller 26a and recovering the post-development developer that has been released from the developing roller 26a. The second transport screw 26b2 agitates and mixes the post-development developer transported from the first transport path B1 with fresh toner supplied from the supply port 26d while transporting them in the longitudinal direction. In this embodiment, the two conveying screws 26b1 and 26b2 are arranged side by side in the horizontal direction. Each of the two conveying screws 26b1 and 26b2 is a screw member in which a screw portion 262 is wound spirally around a rotation shaft 261 (see FIG. 4).

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

[0027] The toner in the toner container 70 is supplied to the developing device 26 from the supply port 26d as needed as the toner in the developing device 26 is consumed. The consumption of the toner in the developing device 26 is detected by a toner concentration sensor 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). In the developing device 26 of this embodiment, as shown by the white arrow in Fig. 3, drive is transmitted (input) to the second transport screw 26b2 from a drive motor (not shown, but installed in the image forming apparatus main body 1). The drive input to the second transport screw 26b2 is then transmitted to the first transport screw 26b1 and the developing roller 26a via a gear train (not shown), causing each member to rotate in the direction of the arrow in Fig. 3.

[0028] The configuration and operation of the developing device 26 as a developer containing device, which is a feature of this embodiment, will be described in detail below. As previously described with reference to FIGS. 2 and 3, the developing device 26 serving as a developer containing device contains a two-component developer serving as a developer. Furthermore, first and second conveying screws 26b1 and 26b2 are provided as rotating members in the developing device 26 (developer storage device). As shown in Fig. 4, each of the first and second conveying screws 26b1 and 26b2 (rotating members) has a screw portion 262 wound spirally around a rotating shaft 261.

[0029] As shown in FIGS. 3 and 4, in this embodiment, the developing device 26 (developer storage device) is provided with first and second conveying screws 26b1 and 26b2 as rotating members, a bearing 26m, a holding member 26n, a sealing member 26t, and the like. In this embodiment, only one end side of the first conveying screw 26b1 (rotating member) is shown in Figure 4 (and Figures 5 and 6 in the modified example described below), but the other end side of the first conveying screw 26b1 and one end side and the other end side of the second conveying screw 26b2 (rotating member) are configured in almost the same way, so explanations of their common configurations will be omitted as appropriate.

[0030] As shown in FIG. 4, the first conveying screw 26b1 as a rotating member is a screw member made up of a rotating shaft 261 made of a resin material and a screw portion 262 wound around the rotating shaft 261 in a spiral shape. In the present embodiment, the first conveying screw 26b1 has a rotating shaft 261 and a screw portion 262 integrally formed from the same resin material by injection molding or the like. The second conveying screw 26b2 is configured in the same manner as the first conveying screw 26b1 (configured as a common part). In this embodiment, the first and second conveying screws 26b1, 26b2 are made of a resin material, but the first and second conveying screws 26b1, 26b2 can also be made of a metal material such as stainless steel. However, when the first and second conveying screws 26b1, 26b2 are made of a resin material as in this embodiment, the device can be made smaller and lighter than when they are made of a metal material.

[0031] As shown in FIG. 4, the bearing 26m rotatably holds the rotary shaft 261, and is a metal bearing made of a metal material. In this embodiment, a ball bearing including an inner ring 26m1, an outer ring 26m2, balls 26m3, and the like is used as the bearing 26m. It is also possible to use bearings 26m (ball bearings) in which a lubricant such as grease is filled in the gap between the inner ring 26m1 and the outer ring 26m2 (around the balls 26m3), or in which sealing seals covering the gap between the inner ring 26m1 and the outer ring 26m2 are provided on both end surfaces.However, these bearings are also defined as being made of metal materials as a whole, since the main components that make up the bearing (the inner ring 26m1, outer ring 26m2, and balls 26m3) are made of metal materials.

[0032] As shown in FIG. 4, the holding member 26n has a bearing 26m made of a metallic material press-fitted into an inner diameter portion 26n1. More specifically, the holding member 26n is a substantially cylindrical member made of a resin material, and is inserted into a hole formed in the developing case 26k with its flange abutting against the outer wall of the developing case 26k (the housing of the developing device 26). Although not shown, the holding member 26n is formed to fit into a stopper portion formed in the hole in the developing case 26k so that the holding member 26n is held non-rotatably in the developing case 26k. A retaining ring is attached to the groove of the rotary shaft 261 protruding outside the holding member 26n (to the right in FIG. 4), and the position of the first conveying screw 26b1 in the developing device 26 in the rotary shaft direction is determined. In this embodiment, the holding member 26n has a flange, but it is also possible to use a member without a flange.

[0033] A bearing 26m (ball bearing) made of a metallic material is press-fitted into an inner diameter portion 26n1 of the holding member 26n. Specifically, the bearing 26m is installed on the holding member 26n so that a portion of the bearing 26m is exposed to the outside (the right side in FIG. 4) of the developing device 26 (developer accommodating device). The holding member 26n into which the bearing 26m is press-fitted as an integral part can also be considered as a single bearing into which the bearing 26m made of a metal material is sub-assembled.

[0034] As shown in FIG. 4, the seal member 26t is in sliding contact with the outer circumferential surface of the rotary shaft 261 at a position inside (on the left side in FIG. 4) the developing device 26 (developer containing device) relative to the bearing 26m. The seal member 26t contacts the inner end surface (the end surface on the left side in FIG. 4) of the bearing 26m at the inner diameter portion 26n1 of the holding member 26n.

[0035] More specifically, in order to reduce the sliding resistance between the seal member 26t and the rotary shaft 261, at least the portion of the seal member 26t that comes into sliding contact with the outer circumferential surface of the rotary shaft 261 is made of a fluororesin material. Specifically, the sealing member 26t in this embodiment is a generally trumpet-shaped flexible sheet member made of polytetrafluoroethylene (PTFE) with a thickness of approximately 0.2 to 0.3 mm. The sealing member 26t has its base attached to the holding member 26n (opposing surface 26n2) so as to be sandwiched between the inner end surface of the bearing 26m and the opposing surface 26n2 of the holding member 26n. In this embodiment, a flexible sheet member made of a fluororesin material is used as the sealing member 26t, but a G-seal, V-ring, or other member made of a rubber material may also be used as the sealing member 26t.

[0036] In this manner, in this embodiment, the seal member 26t is provided inside the device relative to the bearing 26m, thereby reducing the problem of developer getting between the bearing 26m and the rotating shaft 261 of the first conveying screw 26b1.

[0037] In this embodiment, the sealing member 26t is in contact with the inner end face of the bearing 26m made of a metal material, and therefore the heat generated by the sliding contact of the sealing member 26t with the rotating shaft 261 is dissipated through the bearing 26m. In particular, the bearing 26m press-fitted into the holding member 26n has a sufficiently large volume and is in direct contact with the rotating shaft 261, so that the heat of the sealing member 26t and the rotating shaft 261 can be efficiently dissipated to the outside of the device. This reduces the risk of developer in the vicinity clumping together due to heat generated by the sliding contact between the sealing member 26t and the rotating shaft 261. This reduces the risk of developer clumping, which can cause the first conveying screw 26b1 to lock, or of the clumped developer getting mixed into the device and producing abnormal images such as white streaks. Furthermore, since the bearing 26m is press-fitted into the holding member 26n, it is possible to improve workability (and reduce processing costs) compared to when a metal plate is integrally molded into the holding member by inserting it into the holding member.

[0038] The temperature rise ΔT at the portion where the seal member 26t and the rotary shaft 261 are in sliding contact is proportional to the residual heat Q (=amount of generated heat−amount of dissipated heat) at that portion, as shown in the following formula. Temperature rise ΔT ∝ Residual heat Q / Heat capacity C Here, since the amount of heat generated is constant, the bearing 26m is integrated with the seal member 26t to increase the apparent heat capacity C, thereby making it possible to suppress the temperature rise ΔT. Furthermore, in this embodiment, a portion of the bearing 26m is exposed to the outside of the device, so that the amount of heat dissipation is increased, making it possible to suppress the temperature rise ΔT.

[0039] Now, referring to FIG. 4, in this embodiment, the seal member 26t is in sliding contact with the outer peripheral surface of the rotating shaft 261 at the inner diameter portion 26n1 of the holding member 26n (the inner portion where the bearing 26m is not press-fitted). By configuring it in this manner, the seal member 26t is less likely to come into direct contact with the developer flowing inside the developing device than when the seal member 26t is made to slide against the rotating shaft 261 outside the holding member 26n (inside the developing device), thereby reducing deformation and deterioration of the seal member 26t.

[0040] Furthermore, referring to FIG. 4, in this embodiment, the holding member 26n is configured so as not to come into direct contact with the rotation shaft 261. That is, the holding member 26n contacts the rotary shaft 261 via the bearing 26m, and a gap is provided between the inner diameter portion 26n1 and the rotary shaft 261. With this configuration, unlike a configuration in which a portion of the holding member 26n comes into contact with the rotary shaft 261, it is possible to prevent heat generation due to sliding contact with the rotary shaft 261.

[0041] In this embodiment, the seal member 26t is disposed so as to come into contact with the end face of the bearing 26m except for the inner ring 26m1 (the inner ring of the ball bearing). That is, the seal member 26t does not contact the inner ring 26m1, but mainly contacts the end face of the outer ring 26m2. Specifically, the inner diameter of the opposing surface 26n2 of the holding member 26n is configured to be larger than the outer diameter of the inner ring 26m1, and the hole diameter of the opening at the base of the approximately trumpet-shaped seal member 26t is configured to be larger than the outer diameter of the inner ring 26m1. By configuring it in this manner, the path for dissipating heat from the sealing member 26t to the outside of the device (the path passing through the outer ring 26m2) and the path for dissipating heat from the rotating shaft 261 to the outside of the device (the path passing through the inner ring 26m1) are separated, thereby improving the heat dissipation performance of the bearing 26m as a whole. Furthermore, since the seal member 26t does not come into contact with the inner ring 26m1, the problem of the base portion of the seal member 26t being twisted by the inner ring 26m1 rotating together with the rotary shaft 261 can be reduced.

[0042] <Variation 1> As shown in FIG. 5, the developing device 26 in the first modification is different from that shown in FIG. 4 in that the seal member 26t contacts not only the outer ring 26m2 of the bearing 26m (ball bearing) but also the inner ring 26m1. In this configuration, heat dissipation is reduced compared to when the seal member 26t is configured not to come into contact with the inner ring 26m1 of the bearing 26m (ball bearing), but heat generated by the seal member 26t sliding against the rotating shaft 261 of the conveying screws 26b1 and 26bs can be sufficiently dissipated. Also, the workability of the holding member 26n in which the bearing 26m is installed can be improved.

[0043] <Variation 2> As shown in FIG. 6, the developing device 26 in the second modification differs from those shown in FIGS. 4 and 5 in that it uses an oil-impregnated sintered bearing (oil-impregnated sliding bearing) as the bearing 26m. In this configuration, heat dissipation is slightly reduced compared to when the seal member 26t is configured not to come into contact with the inner ring 26m1 of the bearing 26m (ball bearing), but the volume of the portion formed of a metal material is sufficiently large, so that heat generated by the seal member 26t coming into sliding contact with the rotating shaft 261 of the conveying screws 26b1, 26bs can be sufficiently dissipated. In addition, the workability of the holding member 26n in which the bearing 26m is installed can be improved.

[0044] <Experimental Results> FIG. 7 shows the results of an experiment conducted by the inventors of the present invention to confirm the effects of the present invention, and is a graph showing the relationship between the driving time of the developing device 26 and the temperature rise in the vicinity of the seal member 26t. In the experiment, the developing device 26 shown in FIG. 4 as Example 1, the developing device 26 shown in FIG. 5 as Example 2, the developing device 26 shown in FIG. 6 as Example 3, a developing device using a bearing made of a resin material as Comparative Example 1, and a developing device using a bearing with a metal plate embedded between its inner and outer parts (as disclosed in FIG. 12 of Patent Document 1) as Comparative Example 2 were each operated continuously for 60 minutes, and the change in temperature rise ΔT (vertical axis of the graph) near the sealing member 26t was measured. The conditions of each developing device used in the experiment were the same except for the bearings, and the rotating shaft 261 was made of a resin material, had a shaft diameter set to 6 mm, and was set to a rotation speed of 600 rpm. In FIG. 7, graph S1 shows the experimental results of Example 1, graph S2 shows the experimental results of Example 2, graph S3 shows the experimental results of Example 3, graph R0 shows the experimental results of Comparative Example 1, and graph R1 shows the experimental results of Comparative Example 2. The experimental results shown in FIG. 7 also confirm the effects of the present invention described above.

[0045] As described above, developing device 26 in the present embodiment is a developer accommodating device that accommodates developer, and includes conveying screws 26b1 and 26b2 (rotating members) equipped with rotating shaft 261, bearing 26m made of a metal material that rotatably holds rotating shaft 261, holding member 26n having bearing 26m press-fitted into inner diameter portion 26n1, and seal member 26t that comes into sliding contact with the outer circumferential surface of rotating shaft 261 at a position inside developing device 26 relative to bearing 26m. Seal member 26t comes into contact with the inner end face of bearing 26m at inner diameter portion 26n1 of holding member 26n. This allows heat generated by the seal member 26t sliding against the rotary shaft 261 of the conveying screws 26b1 and 26bs to be sufficiently dissipated, thereby improving workability.

[0046] 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.

[0047] 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 the 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 screws are arranged side by side in the horizontal direction, a developing device in which multiple transport screws are arranged side by side in the vertical direction, or a developing device in which a doctor blade is arranged above the developing roller. In this embodiment, the present invention is applied to the developing device 26 that uses a two-component developer consisting of toner and carrier. However, the present invention can also be applied to a developing device that uses a one-component developer consisting of only toner (including external additives, etc.). In such cases, the same effect as that of this embodiment can be obtained.

[0048] Furthermore, in this embodiment, the present invention is applied to the developing device 26 as a developer storage device, but the developer storage device to which the present invention is applied is not limited to this, and can be applied to all devices that store developer inside, such as toner containers, toner replenishing devices, cleaning devices, toner transport devices, and waste toner collection containers. Furthermore, in this embodiment, the screw portions 262 of the first and second conveying screws 26b1 and 26b2 can be formed so that the winding direction from the end to a predetermined range toward the center in the axial direction is opposite to the winding direction in the remaining range. In this configuration, the developer flowing near the holding member 26n (and the bearing 26m) in the developing device 26 is actively replaced. Therefore, the vicinity of the holding member 26n (and the bearing 26m) is more easily cooled, and the developer that has entered the inner diameter portion 26n1 of the holding member 26n and the developer contained in the developing device 26 are less likely to aggregate. In such cases, the same effect as that of this embodiment can be obtained.

[0049] 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]

[0050] 1. Image forming apparatus (image forming apparatus main body), 20, 20Y, 20M, 20C, 20BK process cartridges, 21 photosensitive drum (image carrier), 26 developing device (developer storage device), 26a developing roller, 26b1 first conveying screw (rotating member), 26b2 second conveying screw (rotating member), 26m bearing, 26m1 inner ring, 26m2 outer ring, 26m3 ball, 26n Retaining member, 26n1 inner diameter, 26t sealing material, 261 Rotation axis, 262 Screw section. [Prior art documents] [Patent documents]

[0051] [Patent Document 1] Patent Publication No. 2021-63542

Claims

1. A developer storage device that stores a developer, a rotating member having a rotating shaft; a ball bearing made of a metal material that rotatably holds the rotary shaft; a holding member having the ball bearing press-fitted into an inner diameter portion thereof without contacting the rotating shaft; a seal member that is in sliding contact with an outer circumferential surface of the rotary shaft at a position inside the developer accommodating device with respect to the ball bearing; Equipped with The sealing member is A flexible sheet member, The base portion is cantilevered between the inner end surface of the ball bearing and an opposing surface of the holding member that faces the inner end surface in the inner diameter portion of the holding member, The developer storage device has a tip end that is in sliding contact with the outer circumferential surface of the rotary shaft at the inner diameter portion.

2. A developer storage device as described in Claim 1, characterized in that the sealing member is made of a fluororesin material and is formed in an approximately trumpet shape.

3. A developer storage device as described in claim 1 or claim 2, characterized in that the sealing member is sandwiched between the end face of the outer ring on the inner side of the ball bearing and the opposing surface.

4. A developer storage device as described in Claim 3, characterized in that the sealing member does not contact the inner ring of the ball bearing.

5. A developer storage device as described in any one of claims 1 to 4, characterized in that the sealing member is attached to the opposing surface.

6. A developer storage device as described in any one of claims 1 to 5, characterized in that a portion of the ball bearing is exposed to the outside of the developer storage device.

7. A developing device for developing a latent image formed on a surface of an image carrier, comprising: A developing device comprising the developer storage device according to any one of claims 1 to 6.

8. A process cartridge detachably installed in an image forming apparatus body, 8. A process cartridge comprising the developing device according to claim 7 and the image carrier, the developing device and the image carrier being integrally formed.

9. An image forming apparatus comprising a developer storage device according to any one of claims 1 to 6, or a developing device according to claim 7.

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