DEVELOPER CONTAINING DEVICE, DEVELOPING DEVICE, PROCESS CARTRIDGE, AND IMAGE FORMING APPARATUS

Abstract

To prevent aggregation of developer that enters between a bearing and a collar.SOLUTION: A developer storage device is provided with a second conveying screw 26b2 (rotating member) that is provided with a rotation shaft 261 formed of resin material, a first collar 26s (collar) that is formed of metal material and rotates with the rotation shaft 261, and a bearing 26m that rotatably supports the rotation shaft 261 with the first collar 26s therebetween. The first collar 26s is provided with a flange-like part 26s2 having an outer diameter larger than a collar main part 26s1 that is in slide contact with the bearing 26m on one end in an axial direction located inside a developing device 26.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 that includes the developer storage device, a process cartridge, and an image forming apparatus. [Background technology]

[0002] Conventionally, in a developer storage device (developing device) installed in an image forming device such as a copier or printer, a technology has been known in which the rotating member (conveying screw) is made of a resin material and the rotating shaft of the rotating member is supported by a bearing via a collar (metal collar) made of a metal material, in order to achieve both cost reduction of the rotating member (conveying screw) and improved sliding performance with the bearing (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0003] In the conventional technology, the developer that got between the bearing and the collar could coagulate due to heat generated by the sliding contact between the bearing and the collar. Such developer coagulation could cause the developer to stick between the bearing and the collar, resulting in problems such as the locking of the rotating member.

[0004] 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 in which developer that has entered between the bearing and the collar is less likely to agglomerate. [Means for solving the problem]

[0005] The developer storage device according to the present invention is a developer storage device in which a developer is stored, the developer storage device having a rotating shaft made of a resin material. and a screw portion wound helically around the rotating shaft.a collar made of a metal material and rotating together with the rotary shaft; and a bearing for rotatably supporting the rotary shaft via the collar, the collar having a flange-shaped portion formed on one axial end side located inside the developer accommodating device and having an outer diameter larger than that of a collar main portion that is in sliding contact with the bearing. The flange portion is formed so that its outer diameter is equal to or greater than the outer diameter of the screw portion. It is something. Effect of the Invention

[0006] According to the present invention, it is possible to provide a developer storage device, a developing device, a process cartridge, and an image forming apparatus in which the developer that has entered between the bearing and the collar is less likely to agglomerate. [Brief description of the drawings]

[0007] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. [Diagram 3] FIG. 2 is a diagram showing the developing device in the longitudinal direction. [Figure 4] FIG. 4 is a cross-sectional view showing the vicinity of a bearing that supports a conveying screw. [Diagram 5] FIG. 11 is a cross-sectional view showing the vicinity of a bearing supporting another conveying screw. [Figure 6] FIG. 11 is a cross-sectional view showing the vicinity of a bearing that supports a conveying screw as a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and the duplicated description will be appropriately simplified or omitted.

[0009] First, the overall configuration and operation of an image forming apparatus 1 will be described with reference to FIG. The image forming apparatus 1 in this embodiment is a tandem type color image forming apparatus in which a plurality of process cartridges 20Y, 20M, 20C, and 20BK are arranged side by side so as to face an intermediate transfer belt 40. In addition, a developing device 26 (see FIG. 2) serving as a developer containing device is provided so as to face the photosensitive drums 21 of the plurality of process cartridges 20Y, 20M, 20C, and 20BK.

[0010] In FIG. 1, reference numeral 1 denotes the main body of a color copier as an image forming device, 2 denotes an original transport section which transports an original to an original reading section 3, 3 denotes an original reading section which reads image information of the original, and 4 denotes a writing section (exposure section) which emits laser light based on input image information. Also, 20Y, 20M, 20C, and 20BK denote process cartridges corresponding to the respective colors (yellow, magenta, cyan, and black), and 40 denotes an intermediate transfer belt onto which toner images of a plurality of colors are transferred in an overlapping manner. In addition, 61 indicates a paper feeding device in which sheets P such as paper are stored, 65 indicates a secondary transfer roller that transfers the toner image formed on the intermediate transfer belt 40 to the sheet P, 66 indicates a fixing device that fixes an unfixed image on the sheet P, and 70 indicates 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.

[0011] 2, each of the process cartridges 20Y, 20M, 20C, and 20BK is an integrated unit including 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 for the image forming apparatus main body 1 when it reaches the end of its life. Further, each developing device 26 is disposed so as to face the photosensitive drum 21 of each process cartridge 20Y, 20M, 20C, 20BK. When the developing device 26 reaches the end of its life, it is replaced with a new one in the image forming apparatus main body 1. Note that the operation of attaching and detaching the developing device 26 to and from the image forming apparatus main body 1 and the operation of attaching and detaching the process cartridges 20Y, 20M, 20C, 20BK to and from the image forming apparatus main body 1 can be performed separately and independently. A toner image of each color (yellow, magenta, cyan, black) is formed on the photosensitive drum 21 (image carrier) of each of the process cartridges 20Y, 20M, 20C, and 20BK.

[0012] Hereinafter, the operation of the image forming apparatus during normal color image formation will be described. First, the document is transported from the document table by the transport rollers of the document transport unit 2 and placed on the contact glass of the document reading unit 3. Then, the document reading unit 3 optically reads image information of the document placed on the contact glass. Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 4. Then, from the writing unit 4, laser light (exposure light) based on the image information of each color is irradiated toward the surface of the photosensitive drum 21 (see FIG. 2) of the corresponding process cartridge 20Y, 20M, 20C, and 20BK.

[0013] Meanwhile, each of the four photoconductor drums 21 rotates in a clockwise direction in Fig. 1 and Fig. 2. First, the surface of the photoconductor drum 21 is uniformly charged at a position facing the charging device 22 (charging roller) (charging process). In this way, a charging potential is formed on the photoconductor drum 21. Thereafter, the charged surface of the photoconductor drum 21 reaches a position irradiated with laser light by each writing unit 4, and an electrostatic latent image based on image information is formed at that position (exposure process).

[0014] The laser light corresponding to the yellow component is irradiated onto the surface of the photoconductor drum 21 of the first process cartridge 20Y from the left side of the drawing. At this time, the laser light of the yellow component is scanned in the direction of the rotation axis (main scanning direction) of the photoconductor drum 21 by a polygon mirror rotating at high speed. In this way, an electrostatic latent image corresponding to the yellow component is formed on the photoconductor drum 21 after it has been charged by the charging device 22. Similarly, the cyan laser light is irradiated onto the surface of the photoconductor drum 21 of the second process cartridge 20C from the left on the paper, forming an electrostatic latent image of the cyan component. The magenta laser light is irradiated onto the surface of the photoconductor drum 21 of the third process cartridge 20M from the left on the paper, forming an electrostatic latent image of the magenta component. The black laser light is irradiated onto the surface of the photoconductor drum 21 of the fourth process cartridge 20BK from the left on the paper, forming an electrostatic latent image of the black component.

[0015] Thereafter, the surface of the photoconductor drum 21 on which the electrostatic latent images of each color are formed reaches a position facing the developing device 26. Then, toner of each color is supplied from each developing device 26 onto the photoconductor drum 21, and the latent images on the photoconductor drum 21 are developed (this is the developing process). Thereafter, the surfaces of the photoconductor drums 21 after the developing process reach positions facing the intermediate transfer belt 40. Here, primary transfer rollers 24 are provided at each of the facing positions so as to abut against the inner circumferential surface of the intermediate transfer belt 40. Then, at the positions of the primary transfer rollers 24, the toner images of each color formed on the photoconductor drums 21 are transferred onto the intermediate transfer belt 40 in order, superimposed on top of each other (this is the primary transfer process).

[0016] Then, the surfaces of the photoconductor drums 21 after the primary transfer process reach a position facing the cleaning devices 23. Then, the cleaning devices 23 collect untransferred toner remaining on the photoconductor drums 21 (this is a cleaning process). Thereafter, the residual potential on the surface of the photosensitive drum 21 is removed at the position of the charge removing device, and a series of image forming processes on the photosensitive drum 21 is completed.

[0017] On the other hand, the surface of the intermediate transfer belt 40 onto which the images of each color on the photoconductor drum 21 are transferred and superimposed runs in the direction of the arrow in the figure and reaches the position of the secondary transfer roller 65. Then, at the position of the secondary transfer roller 65, the full-color image on the intermediate transfer belt 40 is secondarily transferred onto the sheet P (secondary transfer process). Thereafter, the surface of the intermediate transfer belt 40 reaches the position of the intermediate transfer belt cleaning device, and the untransferred toner on the intermediate transfer belt 40 is collected by the intermediate transfer belt cleaning device, completing a series of transfer processes on the intermediate transfer belt 40.

[0018] Here, the sheet P conveyed to the position of the secondary transfer roller 65 is conveyed from the paper feeder 61 via the registration roller 64 and the like. Specifically, the sheet P fed by a feed roller 62 from a sheet feeder 61 that stores the sheet P passes through a conveying path and is then guided to the position of a registration roller 64. The sheet P that has reached the position of the registration roller 64 is conveyed toward the position of a secondary transfer roller 65 in synchronization with the toner image on the intermediate transfer belt 40.

[0019] Thereafter, the sheet P onto which the full-color image has been transferred is guided to the position of the fixing device 20. Then, in the fixing device 20, the color image is fixed onto the sheet P at the nip between a fixing roller and a pressure roller. After the fixing process, the sheet P is discharged as an output image outside the apparatus main body 1 by a discharge roller 69, and is then stacked on the discharge tray 5, completing a series of image forming processes.

[0020] Next, the image forming unit of the image forming apparatus will be described in detail with reference to FIG. 2 and FIG. In addition, the four image-forming units installed in the device main body 1 have almost the same structure except for the color of toner used in the image-forming process, so they are illustrated without the alphabetical symbols (Y, M, C, BK) for components such as process cartridges and developing devices.

[0021] As shown in FIG. 2, the process cartridge 20 mainly includes a photosensitive drum 21 as an image carrier, a charging device 22, and a cleaning device 23 housed integrally in a case. The photoconductor drum 21 is a negatively charged organic photoconductor, and is configured by providing a photosensitive layer and the like on a drum-shaped conductive support. The charging device 22 is a charging roller in which a medium-resistance elastic layer is coated on the outer periphery of a conductive core metal. A predetermined voltage is applied from a power supply unit to the charging device 22 (charging roller), thereby uniformly charging the surface of the opposing photoconductor drum 21. The cleaning device 23 is provided with a cleaning blade 25a and a cleaning roller 25b that come into contact with the photoreceptor drum 21. The cleaning blade 25a is made of a rubber material such as urethane rubber, and comes into contact with the surface of the photoreceptor drum 21 at a predetermined angle and with a predetermined pressure. The cleaning roller 25b is a brush roller with brush bristles arranged around a core metal.

[0022] 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, a doctor blade 26c (developer regulating member) facing the developing roller 26a and regulating the amount of developer carried on the developing roller 26a, and the like.

[0023] The developing device 26 contains a developer (two-component developer) made up of a carrier and a toner. The developing roller 26a is configured to form a developing area by facing the photosensitive drum 21 with a small gap therebetween. As shown in Fig. 3, the developing roller 26a is configured with a magnet 26a1 that is fixed inside and forms multiple poles (magnetic poles) on the outer circumferential surface of the roller, and a sleeve 26a2 that rotates around the magnet 26a1.

[0024] 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 (a circulation path indicated by a dashed arrow in FIG. 3). That is, a circulation path for the developer is formed by a first transport path B1 formed by the first transport screw 26b1 and a second transport path B2 formed by the second transport screw 26b2. The first transport path B1 and the second transport path B2 are separated by a partition member 26e (wall portion), and both ends of the two transport paths B1 and B2 in the longitudinal direction communicate with each other via communication openings 26f and 26g. Specifically, referring to FIG. 3, the upstream end of the first transport path B1 in the transport direction communicates with the downstream end of the second transport path B2 in the transport direction via the first communication opening 26f. Also, the downstream end of the first transport path B1 in the transport direction communicates with the upstream end of the second transport path B2 in the transport direction via the second communication opening 26g. That is, the partition member 26e is disposed at a position excluding both ends in the longitudinal direction. The first transport screw 26b1 (first transport path B1) is disposed so as to face the developing roller 26a, and the second transport screw 26b2 (second transport path B2) is disposed so as to face the first transport screw 26b1 (first transport path B1) via a partition member 26e. The first transport screw 26b1 transports the developer in the longitudinal direction while supplying the developer toward the developing roller 26a and recovering the developer after the developing process that has been separated from the developing roller 26a. The second transport screw 26b2 stirs and mixes the developer after the developing process transported from the first transport path B1 and fresh toner supplied from the supply port 26d while transporting them in the longitudinal direction. In this embodiment, the two conveying screws 26b1, 26b2 are arranged side by side in the horizontal direction. Each of the two conveying screws 26b1, 26b2 is a screw member having a screw portion 262 wound in a spiral shape around a rotating shaft 261 (see FIG. 4).

[0025] The above-mentioned image forming process will now be described in more detail, focusing on the development process. The developing roller 26a rotates in the direction of the arrow in Fig. 2. As shown in Fig. 3, the developer in the developing device 26 circulates in the longitudinal direction while being stirred and mixed with the toner supplied from the toner container 70 through the toner supply port 26d via the toner supply path by the rotation in the direction of the arrow of the first transport screw 26b1 and the second transport screw 26b2, which are arranged with a partition member 26e interposed therebetween (circulation in the direction of the dashed arrow in Fig. 3). The toner that is frictionally charged and attracted to the carrier is lifted up onto the developing roller 26a together with the carrier by the developer lifting pole formed on the developing roller 26a. The developer carried on the developing roller 26a is transported in the direction of the arrow in FIG. 2 to reach a position facing the doctor blade 26c. The developer on the developing roller 26a is then transported to a position facing the photoconductor drum 21 (the developing area) after the amount of developer on the developing roller 26a is adjusted to an appropriate amount at this position. The toner is then attracted to the latent image formed on the photoconductor drum 21 by the electric field formed in the developing area. After that, the developer remaining on the developing roller 26a reaches above the first transport path B1 as the sleeve rotates, and is released from the developing roller 26a at this position. Here, the electric field in the developing area is formed by a predetermined voltage (developing bias) applied to the developing roller 26a by the power source for development, and a surface potential (latent image potential) formed on the surface of the photoconductor drum 21 by the charging process and the exposure process.

[0026] The toner in the toner container 70 is appropriately replenished into the developing device 26 through the replenishing port 26d 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 ratio of toner in the developer). The supply port 26d is provided at one end of the second conveying screw 26b2 in the longitudinal direction (the left-right direction in FIG. 3) and above the second conveying screw 26b2 (second conveying path B2). In the developing device 26 in this embodiment, as shown by the white arrow in Fig. 3, the drive is transmitted (input) from a drive motor (not shown, installed in the image forming apparatus main body 1) to the second transport screw 26b2. 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 of the members to rotate in the direction of the arrow in Fig. 3.

[0027] The configuration and operation of developing device 26 as a developer container, which is a characteristic feature of this embodiment, will be described in detail below. As previously described with reference to FIGS. 2 and 3, etc., the inside of the developing device 26 serving as a developer containing device contains a two-component developer serving as a developer. In addition, the developing device 26 (developer storage device) is provided with first and second transport screws 26b1 and 26b2 as screw members. As shown in Fig. 4, each of the first and second transport screws 26b1 and 26b2 (screw members) is formed by winding a screw portion 262 in a spiral shape around a rotating shaft 261 made of metal.

[0028] In the present embodiment, of the two conveying screws 26b1 and 26b2, the second conveying screw 26b2 is a rotating member having a rotation shaft 261 press-fitted with a characteristic collar 26s (first collar) which will be described later. In this embodiment, the first conveying screw 26b1 is configured almost the same as the second conveying screw 26b2, except that a second collar 26t different from the collar 26s (first collar) is press-fitted onto the rotary shaft 261. Therefore, hereinafter, a description of the common components will be omitted as appropriate.

[0029] As shown in Figures 3 and 4, in this embodiment, the developing device 26 (developer storage device) is provided with a second transport screw 26b2 as a rotating member, and a first collar 26s, a second collar 26t, a bearing 26m, a seal member 26n, and the like.

[0030] As shown in FIG. 4, the second conveying screw 26b2 as a rotating member is a screw member including 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 second conveying screw 26b2 is formed integrally with the rotating shaft 261 and the screw portion 262 using the same resin material by injection molding or the like. The first conveying screw 26b1 is also configured similarly to the second conveying screw 26b2 (configured as a common part). By forming the rotating shaft 261 (the first and second conveying screws 26b1, 26b2) from a resin material in this manner, the cost and weight of the device can be reduced compared to when the rotating shaft 261 is formed from a metal material.

[0031] As shown in FIG. 4, the first collar 26s is made of a metal material and is a substantially cylindrical member that rotates together with the rotating shaft 261. In this embodiment, the first collar 26s (collar) is press-fitted onto the rotation shaft 261 of the second conveying screw 26b2. The first collar 26s is interposed between the rotating shaft 261 made of a resin material and the bearing 26m without the rotating shaft 261 directly coming into sliding contact with the bearing 26m. In other words, the bearing 26m rotatably supports the rotating shaft 261 (second conveying screw 26b2) via the first collar 26s.

[0032] If the rotating shaft 261 made of a resin material were configured to directly slide against the bearing 26m, the sliding resistance would increase, causing problems such as the rotating shaft 261 and the bearing 26m becoming more susceptible to wear and deterioration, and the driving torque of the device becoming larger. In contrast, in the present embodiment, the rotating shaft 261 made of a resin material does not directly contact the bearing 26m, but the first collar 26s made of a metal material contacts the bearing 26m. This reduces the sliding resistance between the second conveying screw 26b2 and the bearing 26m, making the above-mentioned problems less likely to occur. The first collar 26s may be made of a material such as SUM (free-cutting steel) having an outer peripheral surface plated with nickel.

[0033] In this embodiment, the first collar 26s (collar) has a flange-shaped portion 26s2 formed on one axial end side (the left side in Figure 4) that is located inside the developing device 26 (developer storage device), the flange-shaped portion 26s2 having an outer diameter larger than that of the collar main portion 26s1 that slides against the bearing 26m. Specifically, in this embodiment, the first collar 26s is formed so that the outer diameter N1 of the collar main portion 26s1 is approximately equal to the inner diameter of the bearing 26m, and the outer diameter N2 of the flange-shaped portion 26s2 is sufficiently larger than the outer diameter N2 of the collar main portion 26s1 (the portion indicated by the dashed line in FIG. 4) (N2>>N1). The first collar 26s is disposed so that the flange-shaped portion 26s2 faces the axial center.

[0034] With reference to FIG. 4, the bearing 26m rotatably supports the rotating shaft 261 via the first collar 26s. More specifically, in this embodiment, the bearing 26m is a sliding bearing made of a low-friction resin material. The bearing 26m is formed in a roughly doughnut shape, and is inserted into a hole formed in the development case (the housing of the developing device 26) with its flange abutting the outer wall of the development case. Although not shown, the bearing 26m is formed to fit into a stopper portion formed in the hole of the development case so that it is held non-rotating in the development case. In addition, with the gear 26x (a gear to which driving force is transmitted from the device main body 1) inserted into the rotating shaft 261 inserted into the bearing 26m, a retaining ring is attached to the groove of the rotating shaft 261 protruding outside the bearing 26m (to the right in Figure 4), and the position of the second conveying screw 26b2 in the developing device 26 in the direction of the rotating shaft is determined.

[0035] Furthermore, a seal member 26n is press-fitted into the inner diameter portion of the bearing 26m. The seal member 26n is a G seal or the like, and is provided with a substantially annular lip portion 26n1 (made of a rubber material with low toner affinity) that comes into sliding contact with the outer circumferential surface of the collar main portion 26s1. Specifically, the lip portion 26n1 comes into sliding contact with the outer circumferential surface of the collar main portion 26s1 in the gap (axial gap) between the flange portion 26s2 and the bearing 26m. This configuration reduces the problem of developer getting between the bearing 26m and the second conveying screw 26b2 (first collar 26s).

[0036] In this manner, in the developing device 26 according to the present embodiment, the rotation shaft 261 (second conveying screw 26b2) made of a resin material is supported by the bearing 26m via the first collar 26s on which the flange-shaped portion 26s2 is formed. Therefore, even if developer gets into the gap between the bearing 26m and the first collar 26s, the developer is less likely to coagulate. More specifically, since the first collar 26s is made of a metal material, its temperature is likely to rise due to sliding contact with the bearing 26m. Therefore, if developer gets between the bearing 26m and the first collar 26s, the developer is likely to coagulate due to the heat of the first collar 26s (heat generated by the sliding contact between the bearing 26m and the first collar 26s). If such developer coagulation occurs, the developer will eventually stick between the bearing 26m and the first collar 26s, making the second transport screw 26b2 more likely to lock. In contrast, the first collar 26s in the present embodiment is formed with the flange-shaped portion 26s2 having a sufficiently large outer diameter, and therefore the heat capacity is increased and heat dissipation is promoted, making it difficult for the temperature to rise, compared to a case in which the flange-shaped portion 26s2 is not formed. Therefore, even if the developer gets between the bearing 26m and the first collar 26s, the developer is unlikely to aggregate.

[0037] In the present embodiment, the flange portion 26s2 of the first collar 26s is positioned inside the developing device 26 and is configured so that a part or the whole of it is submerged in the developer inside the device. Therefore, compared to when the flange portion 26s2 is not formed, the area in contact with the developer in the device is wider, and the heat of the first collar 26s is diffused by the developer flowing in the device, making it easier to cool the first collar 26s. Therefore, even if the developer gets between the bearing 26m and the first collar 26s, the developer is less likely to aggregate. In addition, since the temperature of the first collar 26s itself is less likely to rise, the developer contained in the developing device 26 is less likely to aggregate due to heat, and problems such as abnormal images caused by toner aggregation, such as white streaks, are also reduced.

[0038] In particular, in this embodiment, the flange-shaped portion 26s2 of the first collar 26s is formed so that its outer diameter N2 is equal to or greater than the outer diameter of the screw portion M (N2>M). Therefore, the heat capacity of the first collar 26s is sufficiently increased, and the temperature rise becomes more difficult. Therefore, even if developer gets between the bearing 26m and the first collar 26s, the developer becomes more difficult to aggregate. In addition, the developer contained in the developing device 26 also becomes more difficult to aggregate, and abnormal images such as white streaks become less likely to occur.

[0039] In this embodiment, the first collar 26s (collar) is disposed so that the flange-shaped portion 26s2 can come into contact with the screw portion 262, as shown in FIG. With this configuration, it becomes easier to determine the axial position of first collar 26s without installing a retaining ring or the like that can come into contact with the end face of flange-shaped portion 26s2 on rotating shaft 261. In particular, in this embodiment, first collar 26s is press-fitted onto rotating shaft 261, and in the assembly process for press-fitting, first collar 26s only needs to be press-fitted to a position where it abuts against screw portion 262, which makes the assembly work easier and reduces variation in the press-fitting position.

[0040] In the present embodiment, the second conveying screw 26b2 as a rotating member does not have a portion having a larger outer diameter than the rotating shaft 261, except for the screw portion 262. In other words, the second conveying screw 26b2 does not have a flange portion or the like having a larger outer diameter than the rotating shaft 261, except for the screw portion 262. Therefore, the developer flowing inside the developing device 26 is more likely to come into contact with the flange portion 26s2 of the second transport screw 26b2 without losing momentum, compared to when such a portion with a large outer diameter is formed. Therefore, the effect of cooling the first collar 26s described above is more likely to be achieved.

[0041] As shown in FIG. 4, in the developing device 26 of the present embodiment, an axial gap is formed between the flange portion 26s2 and the bearing 26m. That is, the flange portion 26s2 is disposed inside the developing device 26 at a position sufficiently separated from the bearing 26m. This allows the flange-shaped portion 26s to easily come into contact with the developer that flows smoothly inside the developing device 26, making it easier to achieve the effect of cooling the first collar 26s described above.

[0042] Also, referring to Figure 3 (and Figure 5), in this embodiment, the rotating shaft 261 of the second conveying screw 26b2 (rotating member) has a first collar 26s (collar) installed on one side in the axial direction, which is the driving side (the side where the gear 26x to which the drive is input is installed, which is the right side in Figure 3), and a cylindrical second collar 26t (see Figure 5) installed on the other side in the axial direction, which is the non-driving side (the left side in Figure 3). The second collar 26t is configured almost the same as the first collar 26s, except for the fact that the flange portion 26s2 is not formed and the installation position. The reason for this configuration is that the torque applied to the rotating shaft 261 on the non-drive side is smaller than that on the drive side, and the sliding resistance between the bearing 26m and the rotating shaft 261 (collar) is smaller, so that the temperature of the collar is less likely to rise. In other words, the temperature of the second collar 26t is less likely to rise than that of the first collar 26s. In addition, the second collar 26t is less expensive than the first collar 26s since the flange portion 26s2 is not formed. For this reason, in this embodiment, the present invention is applied only to the first collar 26s, which is prone to temperature rise (by providing a flange-shaped portion 26s2), and is not applied to the second collar 26t, thereby efficiently solving the problem that the present invention aims to solve and reducing the cost of the device.

[0043] Also, referring to Figures 3 and 5, the first conveying screw 26b1 in this embodiment uses a second collar 26t (a cylindrical collar without a flange-shaped portion) as two collars that are pressed into both ends of the rotating shaft 261. The reason for this configuration is that the torque applied to the rotating shaft 261 of the first conveying screw 26b1 is smaller than that of the driving side of the second conveying screw 26b2, and the sliding resistance between the bearing 26m and the rotating shaft 261 (collar) is small, so that the temperature of the collar is less likely to rise. In other words, the temperature of the second collar 26t installed on the first conveying screw 26b1 is less likely to rise than that of the first collar 26s installed on the second conveying screw 26b2. In addition, the second collar 26t is less expensive than the first collar 26s since the flange portion 26s2 is not formed. For this reason, in this embodiment, the present invention is not applied to the first conveying screw 26b1, which is less likely to experience a temperature rise (the flange-shaped portion 26s2 is not provided). In other words, of the four collars provided on the first and second conveying screws 26b1 and 26b2, the flange-shaped portion 26s2 is provided only on the collar that is most likely to experience a temperature rise (the collar provided on the driving side of the second conveying screw 26b2). This efficiently solves the problem that the present invention is intended to solve, and reduces the cost of the device.

[0044] <Modification> As shown in FIG. 6, in a modified developing device 26 (developer storage device), the screw portions 262a, 262b of the second transport screw 26b2 as a rotating member are formed so that the winding direction (the winding direction of the second screw portion 262b) from the end portion that can contact the flange-shaped portion 26s2 of the first collar 26s (collar) to a predetermined range toward the axial center is opposite to the winding direction of the other ranges (the winding direction of the first screw portion 262a). Specifically, the second conveying screw 26b2 is formed with a second screw portion 262b at the axial end portion on the first collar 26s side as a screw portion wound around the rotating shaft 261, and a first screw portion 262a is formed in the remaining portion. The winding direction (spiral direction) of the first screw portion 262a is the same as that of the screw portion 262 in FIG. 4, and the winding direction of the second screw portion 262b is opposite to that of the first screw portion 262a. In addition, the screw pitch and outer diameter of both screw portions 262a and 262b are the same as those of the screw portion 262 in FIG. 4. The range in which the second screw portion 262b is formed is at least one screw pitch. By providing the second screw portion 262b with the winding direction in the opposite direction in this manner, the developer flowing near the flange portion 26s2 in the developing device 26 comes into contact with the flange portion 26s2 while actively replacing itself. Therefore, the first collar 26s is easily cooled, and the developer that has entered between the bearing 26m and the first collar 26s and the developer contained in the developing device 26 are less likely to aggregate.

[0045] As described above, the developing device 26 in this embodiment is a developer containing device in which a developer is contained, and includes the second transport screw 26b2 (rotating member) having the rotating shaft 261 made of a resin material, the first collar 26s (collar) made of a metal material and rotating together with the rotating shaft 261, and the bearing 26m that rotatably supports the rotating shaft 261 via the first collar 26s. The first collar 26s is formed, at one axial end located inside the developing device 26, with a flange-shaped portion 26s2 having an outer diameter larger than that of the collar main portion 26s1 that comes into sliding contact with the bearing 26m. This makes it possible to prevent the developer that has entered between the bearing 26m and the first collar 26s from coagulating.

[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 alone. Alternatively, the developing device 26 can be one of the components of the process cartridge 20, and can be configured to be attached to and detached from the image forming apparatus main body 1 as a process cartridge. In such a case, the same effect as that of this embodiment can be obtained. In this application, a "process cartridge" is defined as a unit in which at least one of a charging device for charging an image carrier, a developing device for developing a latent image formed on the image carrier, and a cleaning device for cleaning the image carrier is integrated with an image carrier, and is configured to be detachable from the main body of an image forming apparatus.

[0047] In this embodiment, the present invention is applied to a developing device 26 in which two transport screws 26b1, 26b2 (transport members) are arranged side by side in the horizontal direction, and a doctor blade 26c is arranged below a developing roller 26a. However, the configuration of the developing device to which the present invention is applied is not limited to this, and the present invention can be applied to, for example, a developing device in which three or more transport screws are arranged side by side in the horizontal direction, a developing device in which a plurality of transport screws are arranged side by side in the vertical direction, or a developing device in which a doctor blade is arranged above a developing roller. In the present embodiment, the present invention is applied to the developing device 26 that uses a two-component developer made of toner and carrier. However, the present invention can also be applied to a developing device that uses a one-component developer made of only toner (including external additives, etc.). In such cases, substantially the same effects as those of this embodiment can be obtained.

[0048] In addition, in this embodiment, the present invention is applied to 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. In the present embodiment, the flange 26s2 is provided only on the driven collar (first collar 26s) of the two collars 26s, 26t pressed into the second transport screw 26b2 as a rotating member, but the flange can also be provided on the non-driven collar (second collar 26t). Also, at least one of the two collars pressed into the first transport screw 26b1 as a rotating member can be provided with a flange. Furthermore, the present invention can also be applied to a rotating member other than the transport screws 26b1, 26b2 (for example, the developing roller 26a). In these cases, the same effects as those of the present embodiment can be obtained.

[0049] It is clear that the present invention is not limited to the present embodiment, and that each embodiment may be appropriately modified within the scope of the technical concept of the present invention in addition to what is suggested in each embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and may be any number, position, shape, etc. suitable for implementing the present invention. [Explanation of symbols]

[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 (screw member), 26b2 second conveying screw (rotating member, screw member), 26m bearing, 26n Sealing material, 26n1 Lip part, 26s 1st color (color), 26s1 collar main part, 26s2 flange part, 26t 2nd color, 261 Rotation axis, 262 Screw section, 262a: first screw section; 262b: second screw section. [Prior art documents] [Patent documents]

[0051] [Patent Document 1] JP 2010-134427 A

Claims

1. A developer storage device in which a developer is stored, A screw member including a rotating shaft made of a resin material and a screw portion wound helically around the rotating shaft; A collar made of a metal material and rotating together with the rotating shaft; a bearing that rotatably supports the rotating shaft via the collar; Equipped with the collar has a flange-shaped portion formed on one axial end side located inside the developer accommodating device, the flange-shaped portion having an outer diameter larger than that of a collar main portion that is in sliding contact with the bearing, The developer accommodating device, wherein the flange portion is formed so that an outer diameter thereof is equal to or greater than an outer diameter of the screw portion.

2. A developer storage device as described in Claim 1, characterized in that the collar is arranged so that the flange-shaped portion can contact the screw portion.

3. A developer storage device as described in Claim 2, characterized in that the screw portion is formed so that the winding direction from the end portion that can contact the flange-shaped portion to a predetermined range toward the axial center is opposite to the winding direction in other ranges.

4. A developer storage device as described in any one of claims 1 to 3, characterized in that the screw member has no portion, except for the screw portion, having an outer diameter larger than that of the rotating shaft.

5. A developer storage device as described in any one of claims 1 to 4, characterized in that the collar is provided on one side of the rotating shaft in the axial direction, which is the driving side, and a cylindrical second collar is provided on the other side of the axial direction, which is the non-driving side.

6. A developer storage device as described in any one of claims 1 to 5, characterized in that an axial gap is formed between the flange-shaped portion and the bearing.

7. A developer storage device as described in Claim 6, characterized in that it is provided with a sealing member that is pressed into the inner diameter portion of the bearing and has a lip portion that slides against the outer peripheral surface of the collar main portion in the gap.

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

9. A process cartridge detachably installed in an image forming apparatus body, 9. A process cartridge comprising the developing device according to claim 8 and said image carrier integrally formed therewith.

10. An image forming apparatus comprising: a developer storage device according to any one of claims 1 to 7; or a developing device according to claim 8.

Images