Developing unit and image formation device

Abstract

To suppress the increase of costs for preventing toner leakage unlike the situation where component replacement is made such that magnets and magnetic plates are arranged around the whole circumferences of end portions.SOLUTION: Provided is a developing unit comprising: a developer holding body 334 where adsorption areas, except end portions, absorbing developer containing toner and carrier, are set, and which holds, in the absorption areas, the developer to be supplied to an image holding body that forms an electrostatic latent image; magnetic plates 51 and 52 located in a second range 50b except a first range 50a in a circumferential direction S at the end portions of the developer holding body 334; and magnets forming a magnetization pattern 60 in a circumferential direction S corresponding to the first range 50a in combination thereof.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a developing unit and an image forming apparatus. [Background technology]

[0002] For example, Patent Document 1 discloses a developing device having a developer container filled with developer, a developing sleeve that incorporates a magnet and is rotatably attached to the opening of the developer container and transports developer to an electrostatic latent image formed on a photosensitive member, and a magnetic seal member whose inner circumferential surface is magnetized with multiple N and N poles and which is disposed at both ends of the developing sleeve at a predetermined distance from the outer circumferential surface of the developing sleeve, wherein the N and N poles magnetized on the inner circumferential surface of the multiple N and N poles are magnetized at an angle to the longitudinal direction of the developing sleeve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-354855 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a developer holder in which an attraction region that attracts a developer containing toner and a carrier is set by the internal arrangement of a magnet and the developer supplied to an image holder that forms an electrostatic latent image is held in the attraction region, toner leakage at the end where the magnet is not internally arranged can cause contamination inside and outside the developing device. In order to prevent such toner leakage, a configuration in which a magnet and a magnetic plate are additionally arranged at the end of the developer holder can be considered. However, depending on the configuration of the end, it may be difficult to additionally arrange at least one of a magnet and a magnetic plate around the entire circumference of the end, and in such cases, it may be necessary to change the components. An object of the present invention is to suppress an increase in cost for preventing toner leakage, compared to a case in which components are changed in order to arrange magnets and a magnetic plate around the entire circumference of the end portion. [Means for solving the problem]

[0005] The invention described in claim 1 is a developing unit comprising a developer holder in which an adsorption area, which is an area for adsorbing a developer containing toner and a carrier, is set except for the ends, and which holds the developer in the adsorption area when it is supplied to an image holder that forms an electrostatic latent image; a magnetic plate located in a second range in the circumferential direction at the end of the developer holder, excluding a first range; and a magnet that, when combined with the magnetic plate, forms a circumferential magnetization pattern corresponding to the first range. The invention described in claim 2 is the developing unit described in claim 1, characterized in that the magnetization pattern changes a plurality of times in the circumferential direction. The invention described in claim 3 is the developing device described in claim 2, characterized in that at least a portion of the magnetization pattern in the first range is formed by arranging magnetic poles of a magnet in the circumferential direction of the developer holder. The invention described in claim 4 is the developing device described in claim 2, characterized in that at least a portion of the magnetization pattern in the second range is formed by arranging magnetic poles of a magnet in the axial direction of the developer holder. The invention described in claim 5 is the developing unit described in claim 4, characterized in that the magnet, whose magnetic poles are arranged in the axial direction, is arranged at the upstream and downstream ends of the circumferential direction of the developer holder and is also arranged close to the magnetic plate. The invention described in claim 6 is the developing device described in claim 2, characterized in that the magnet that forms the magnetization pattern in the first area and the magnet that forms the magnetization pattern in the second area are in contact with each other. The invention described in claim 7 is the developing unit described in claim 2, characterized in that at least a portion of the magnetization pattern in the first range is formed by a first circumferential array in which magnetic poles of magnets are arranged in the circumferential direction, and at least a portion of the magnetization pattern in the second range is formed by a second circumferential array in which magnetic poles of magnets are arranged in the circumferential direction, and which has a different axial position from the magnets in the first circumferential array. The invention described in claim 8 is the developing device described in claim 2, characterized in that at least a portion of the magnetization pattern in the first range is formed by arranging the magnetic poles of a magnet in a first direction, and at least a portion of the magnetization pattern in the second range is formed by arranging the magnetic poles of a magnet in a second direction different from the first direction. The invention described in claim 9 is the developing device described in claim 8, characterized in that the first direction is the circumferential direction of the developer holder, and the second direction is the axial direction of the developer holder. The invention described in claim 10 is the developing device described in claim 8, characterized in that the first direction is the circumferential direction of the developer holder, and the second direction is a direction intersecting the circumferential direction and the axial direction of the developer holder. The invention described in claim 11 is the developing device described in claim 8, characterized in that the first direction is a first intersecting direction that intersects the circumferential direction of the developer holder and the axial direction of the developer holder, and the second direction is a second intersecting direction that intersects the circumferential direction, the axial direction, and the first intersecting direction. The invention described in claim 12 is an image forming apparatus including an image holder that forms an electrostatic latent image, a developing means that develops the electrostatic latent image formed on the image holder into a toner image, a transfer means that transfers the toner image by the developing means onto a recording material, and a fixing means that fixes the toner image transferred onto the recording material to the recording material, wherein the developing means has an adsorption area that adsorbs a developer containing toner and a carrier, and is set except for the ends, and the developing means is equipped with a developer holder that holds the developer supplied to the image holder that forms the electrostatic latent image in the adsorption area, and a magnetic plate located in a second range excluding a first range in the circumferential direction at the end of the developer holder, and a magnet that forms a circumferential magnetization pattern corresponding to the first range when combined with the magnetic plate. Effect of the Invention

[0006] According to the invention of claim 1, it is possible to suppress an increase in cost for preventing toner leakage, compared to a case in which components are changed in order to arrange magnets and a magnetic plate around the entire circumference of the end portion. According to the invention of claim 2, the magnetization pattern changes multiple times in the circumferential direction, so that toner leakage can be prevented more reliably than in a case where the magnetization pattern does not change multiple times in the circumferential direction. According to the invention of claim 3, at least a portion of the magnetization pattern in the first range can suppress an increase in starting torque compared to a case in which the magnetization pattern is not formed by arranging magnetic poles of a magnet in the circumferential direction of the developer holder. According to the invention of claim 4, at least a portion of the magnetization pattern in the second range can more reliably prevent toner leakage in the axial direction compared to a case in which the magnetization pattern is not formed by arranging magnetic poles of a magnet in the axial direction of the developer holder. According to the invention of claim 5, the magnets, whose magnetic poles are arranged in the axial direction, are arranged at the most upstream and most downstream sides of the circumferential direction of the developer holder and are also arranged closer to the magnetic plate, so that toner leakage in the circumferential direction can be more reliably prevented than in the case where the magnets are not arranged at the most upstream and downstream sides of the developer holder and are also arranged closer to the magnetic plate. According to the invention of claim 6, toner leakage can be more reliably prevented compared to a case in which the magnets forming the magnetization pattern in the first area and the magnets forming the magnetization pattern in the second area are not in contact with each other. According to the invention of claim 7, at least a portion of the magnetization pattern in the first range is formed by a first circumferential arrangement in which the magnetic poles of the magnets are arranged in a circumferential direction, and at least a portion of the magnetization pattern in the second range is formed by a second circumferential arrangement in which the magnetic poles of the magnets are arranged in a circumferential direction, and toner leakage can be more reliably prevented compared to a case in which the magnetization pattern is not formed by the second circumferential arrangement in which the axial position of the magnets in the first circumferential arrangement is different. According to the invention of claim 8, at least a portion of the magnetization pattern in the first range is formed by arranging the magnetic poles of a magnet in a first direction, and at least a portion of the magnetization pattern in the second range is formed by arranging the magnetic poles of a magnet in a second direction different from the first direction, so that toner leakage can be more reliably prevented compared to a case where the configuration is not included. According to the invention of claim 9, toner leakage can be more reliably prevented compared to a case in which the first direction is the circumferential direction of the developer holder and the second direction is the axial direction of the developer holder. According to the invention of claim 10, the first direction is the circumferential direction of the developer holder, and the second direction is a direction intersecting the circumferential direction and the axial direction of the developer holder, so that toner leakage can be more reliably prevented compared to a case where the configuration is not provided. According to the invention of claim 11, the first direction is a first intersecting direction that intersects with the circumferential direction of the developer holder and the axial direction of the developer holder, and the second direction is a second intersecting direction that intersects with the circumferential direction, the axial direction, and the first intersecting direction, so that toner leakage can be more reliably prevented compared to a case where the configuration is not provided. According to the invention of claim 12, it is possible to suppress an increase in costs for preventing toner leakage, compared to a case in which components are changed in order to arrange magnets and a magnetic plate around the entire circumference of the end portion. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an image forming apparatus. [Diagram 2] FIG. 2 is a diagram illustrating a developing device of the image forming apparatus. [Diagram 3] FIG. 2 is a perspective view illustrating a more specific configuration of a developing unit. [Figure 4] 4 is a cross-sectional view of the developing unit as viewed from the inner surface side of the front member. FIG. [Diagram 5] 4 is a cross-sectional view illustrating the relationship between the developing roll, the metal plate, and the sheet-shaped magnet. FIG. [Figure 6] FIG. 4 is a perspective view illustrating the relationship between the developing roll, the metal plate, and the sheet-shaped magnet. [Figure 7] FIG. 2 is a diagram illustrating a first example of a magnetization pattern. [Figure 8] FIG. 11 is a diagram illustrating a second example of the magnetization pattern. [Figure 9] FIG. 11 is a diagram illustrating a third example of the magnetization pattern. [Figure 10] FIG. 11 is a diagram illustrating a fourth example of the magnetization pattern. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram illustrating an image forming apparatus 1. As shown in FIG. The image forming apparatus 1 according to this embodiment includes a paper feed unit 1A, a printing unit 1B, and a paper discharge unit 1C. The paper feed unit 1A includes a first paper storage section 11 to a fourth paper storage section 14 for storing paper P as an example of a recording medium. The paper feed unit 1A also has feed rolls 15-18 that correspond to the first paper storage section 11 to the fourth paper storage section 14, respectively, and feed the paper P stored in each paper storage section to a transport path connected to the printing unit 1B.

[0009] The printing unit 1B includes an image forming section 20 that forms an image on a sheet P. The printing unit 1B also includes a control section 21 that controls each section of the image forming apparatus 1. The printing unit 1B also includes an image processing section 22. The image processing section 22 performs image processing on image data transmitted from the image reading device 4 and the personal computer (PC) 5. The printing unit 1B is also provided with a UI (User Interface) 23, which is configured with a touch panel or the like and notifies the user of information and receives information input from the user.

[0010] Image forming section 20, as an example of an image forming means, is provided with six image forming units 30T, 30P, 30Y, 30M, 30C, and 30K (hereinafter, sometimes simply referred to as "image forming units 30") arranged in parallel at regular intervals. Each image forming unit 30 includes a photosensitive drum 31 on which an electrostatic latent image is formed while rotating in the direction of arrow A, a charging roll 32 which charges the surface of the photosensitive drum 31, a developing device 33 which develops the electrostatic latent image formed on the photosensitive drum 31, and a drum cleaner 34 which removes toner and the like from the surface of the photosensitive drum 31. The photoconductor drum 31 is an example of an image carrier.

[0011] The image forming section 20 is also provided with a laser exposure device 26 that exposes the photoconductor drum 31 of each image forming unit 30 to laser light. The exposure of the photoconductor drum 31 by the laser exposure device 26 is not limited to using laser light. For example, a light source such as an LED (Light Emitting Diode) may be provided for each image forming unit 30, and the photoconductor drum 31 may be exposed using light emitted from the light source.

[0012] Each image forming unit 30 is configured similarly, except for the toner contained in the developer 33. The image forming units 30Y, 30M, 30C, and 30K form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Further, the image forming units 30T and 30P form toner images using toner corresponding to a corporate color, foaming toner for Braille, fluorescent color toner, toner for improving gloss, etc. In other words, the image forming units 30T and 30P form toner images using toner of a special color.

[0013] The image forming section 20 is also provided with an intermediate transfer belt 41 onto which the toner images of each color formed on the photosensitive drums 31 of the image forming units 30 are transferred. The image forming section 20 is also provided with a primary transfer roll 42 that transfers the respective color toner images of the respective image forming units 30 onto the intermediate transfer belt 41 at a primary transfer portion T1. The image forming unit 20 is also provided with a secondary transfer roll 40 that transfers the toner image transferred onto the intermediate transfer belt 41 onto the paper P at a secondary transfer portion T2. Furthermore, the image forming section 20 is provided with a belt cleaner 45 that removes toner and the like from the surface of the intermediate transfer belt 41, and a fixing device 80 that fixes the secondarily transferred image onto the paper P.

[0014] The image forming unit 20 performs an image forming operation based on a control signal from the control unit 21 . Specifically, in the image forming unit 20, first, image processing is performed on the image data input from the image reading device 4 or the PC 5 by the image processing unit 22, and the image data after image processing is supplied to the laser exposure device 26. Then, for example, in a magenta (M) image forming unit 30M, the surface of the photosensitive drum 31 is charged by the charging roll 32, and then the laser exposure device 26 irradiates the photosensitive drum 31 with laser light modulated by image data obtained from the image processing unit 22.

[0015] As a result, an electrostatic latent image is formed on the photoconductor drum 31 . The formed electrostatic latent image is developed by the developing unit 33, and a magenta toner image is formed on the photosensitive drum 31. Similarly, yellow, cyan and black toner images are formed in the image forming units 30Y, 30C and 30K, and special color toner images are formed in the image forming units 30T and 30P.

[0016] The respective color toner images formed in each image forming unit 30 are electrostatically transferred sequentially by a primary transfer roll 42 onto an intermediate transfer belt 41 rotating in the direction of arrow C in Figure 1, and superimposed toner images are formed on the intermediate transfer belt 41. The superimposed toner image formed on the intermediate transfer belt 41 is transported to a secondary transfer portion T2 constituted by a secondary transfer roll 40 and a backup roll 49 as the intermediate transfer belt 41 moves.

[0017] On the other hand, the paper P is taken out from the first paper storage unit 11 by, for example, the delivery roll 15, and then transported to the position of the registration roll 74 via the transport path. When the superimposed toner image is transported to the secondary transfer portion T2, a sheet of paper P is supplied from the registration roll 74 to the secondary transfer portion T2 in accordance with the transport timing. Then, in the secondary transfer portion T2, the superimposed toner images are electrostatically transferred onto the paper P all at once by the action of a transfer electric field formed between the secondary transfer roll 40 and the backup roll 49.

[0018] Thereafter, the paper P onto which the superimposed toner images have been electrostatically transferred is transported to a fixing device 80. In the fixing device 80, pressure and heat are applied to the paper P on which the unfixed toner image has been formed, and the toner image is fixed to the paper P. Then, the sheet P on which the fixing process has been performed passes through a curl correction section 81 provided in the sheet discharge unit 1C, and is then conveyed to a sheet stacking section (not shown).

[0019] FIG. 2 is a diagram illustrating the developing device 33 of the image forming apparatus 1. As shown in FIG. The developing unit 33 includes a container 331 that contains a developer (not shown). The container 331 is configured with a container housing 332 made of resin. The housing 332 of the developing device 33 is arranged to extend along a direction perpendicular to the paper surface of FIG. 2, which is the direction from the front side to the rear side of the image forming apparatus 1 (see FIG. 1), and has a front side member 33a (see FIG. 3) on the front side and a rear side member 33b (see the same figure) on the rear side.

[0020] An opening 333 is provided in the housing 332 at a location facing the photoconductor drum 31 (see FIG. 1). A developing roll 334 that adheres a developer to the surface of the photoconductor drum 31 is provided in the opening 333. The developing roll 334, which is an example of a developer holder, is formed in a cylindrical shape and is arranged so as to extend along a direction from the front side to the rear side of the image forming apparatus 1. In addition, the developing roll 334 is arranged so as to extend along the longitudinal direction of the developing unit 33.

[0021] The developing roll 334 is provided with a developing sleeve 334A that is formed of a cylindrical body and that is driven to rotate, and a magnet roll 334B that is disposed inside the developing sleeve 334A. The developing sleeve 334A is made of a metal such as SUS, etc. The developing sleeve 334A rotates in the direction of the arrow D in the figure. The developing roll 334 is an example of a developer carrier.

[0022] Furthermore, in this embodiment, at the primary transfer portion T1 (see FIG. 1) between the developing roll 334 and the photosensitive drum 31, the developing sleeve 334A and the photosensitive drum 31 rotate so that they move in the same direction. The developing unit 33 is provided with a layer regulating member 335 that regulates the layer thickness of the developer held on the developing roll 334 .

[0023] As shown in FIG. 2, the developing device 33 is provided with a first transport member 336 and a second transport member 337 for transporting the developer. The first transport member 336 and the second transport member 337 are provided on the opposite side to the side on which the photoconductor drum 31 (see FIG. 1) is installed, with the developing roll 334 interposed therebetween. The first transport member 336 has a rotation axis aligned with the rotation axis of the developing sleeve 334A that is driven to rotate, and rotates around this rotation axis to transport the developer in the container 331.

[0024] In the developing device 33 configured in this manner, new toner or toner to which a very small amount of carrier has been added is circulated by being stirred and transported between the first transport member 336 and the second transport member 337. More specifically, by transferring the developer through connection ports formed at both ends of a partition wall extending in the axial direction, the developer stirred by the first transport member 336 is stirred by the second transport member 337, and can also be stirred by the first transport member 336. In the developing device 33, a circulation path is formed, which is a path that circulates in the axial direction by the rotation of each of the first transport member 336 and the second transport member 337.

[0025] The developing unit 33 is provided with a third transport member 338 adjacent to the second transport member 337. In addition, the developing unit 33 is provided with a pick-up roll 339 located above the third transport member 338. The transport path formed by the rotation of the third transport member 338 is connected to the circulation path described above, and receives the developer from the circulation path. The third transport member 338 supplies the developer to a pickup roll 339. The pickup roll 339 supplies the developer to the developing roll 334. For example, the first transport member 336 transports toward the front side of the paper, the second transport member 337 transports toward the back side of the paper, and the third transport member 338 transports toward the front side of the paper.

[0026] The developing roll 334, the layer regulating member 335, the first transport member 336, the second transport member 337, the third transport member 338 and the pickup roll 339 are disposed substantially parallel to the photoconductor drum 31 (see FIG. 1).

[0027] Next, a more specific configuration of the developing unit 33 will be described. Fig. 3 is a perspective view for explaining a more specific configuration of the developing unit 33. Note that Fig. 3 shows a state in which the pick-up roll 339 (see Fig. 2) has been removed. 3, the developing unit 33 has a front member 33a located on the front side and a rear member 33b located on the rear side as members constituting a part of the housing 332 (see FIG. 2). The front member 33a is separated from the developing roll 334 in the axial direction J. Each end of the developing roll 334 is rotatably held by the front member 33a and the rear member 33b. An inner surface 33c of the front side member 33a faces the rear side member 33b, and an outer surface 33d is a surface located on the opposite side to the rear side member 33b.

[0028] 4 is a cross-sectional view of the developing unit 33 as viewed from the inner surface 33c side of the front side member 33a, and shows an enlarged view of the periphery of the developing roll 334. Note that the first transport member 336 is not shown in FIG. As shown in FIG. 4, the developing unit 33 includes a cover member 33e having an arc-shaped cross section that covers a part of the developing roll 334.

[0029] Further, the developing unit 33 is provided on the front side member 33a with magnetic metal plates 51 and 52 and a sheet-shaped magnet 53. The metal plates 51 and 52 are disposed at different positions in the vertical direction, with the metal plate 51 located on the upper side and the metal plate 52 located on the lower side.

[0030] The metal plates 51 and 52 are provided on the inner surface 33c of the front side member 33a at positions adjacent to the developing roll 334. More specifically, the metal plate 51 is located closer to the cover member 33e, and the metal plate 52 is located between the first conveying member 336 and the developing roll 334. The sheet-shaped magnet 53 is provided along the circumferential direction S of the developing roll 334. The sheet-shaped magnet 53 has a portion located between the metal plates 51, 52 in the circumferential direction S.

[0031] A magnetic pattern is formed on the metal plates 51 and 52 by the magnetic force of the developing roll 334. The sheet magnet 53 has a magnetic pattern in one predetermined direction. The magnetic pattern referred to here indicates the range of magnetic force, the north and south pole boundaries and arrangement. The metal plates 51 and 52 and the sheet magnet 53 are provided in the vicinity of the developing roll 334, and the gap therebetween may be, for example, 1 mm.

[0032] 5 and 6 are diagrams for explaining the relationship between the developing roll 334, the metal plates 51 and 52, and the sheet magnet 53, with FIG. 5 being a cross-sectional view and FIG. 6 being a perspective view. As shown in Fig. 5, the metal plate 51 is provided on the inner surface 33c of the front side member 33a. That is, the metal plate 51 is located at the end of the developing roll 334. Note that, although the metal plate 52 (see Fig. 4) is not shown in Fig. 5, it is located at the end of the developing roll 334, just like the metal plate 51. In FIG. 5, the front side member 33a is shown in cross section, and the portion of the developing roll 334 beyond the front side member 33a is omitted.

[0033] The sheet magnet 53 is provided in a recess 33f formed in the front member 33a. More specifically, the sheet magnet 53 is located between the inner surface of the recess 33f and the developing roll 334. The sheet magnet 53 is provided around the entire circumference of the developing roll 334. More specifically, the recess 33f is located closer to the end than the metal plate 51 in the axial direction J of the developing roll 334. Therefore, the sheet magnet 53 is located closer to the end than the metal plate 51 (to the left in FIG. 5).

[0034] 6, the magnetization pattern of the sheet magnet 53 is indicated by a thick line, and the flow of the toner in a floating state at the end of the developing roll 334 is indicated by a dashed arrow. Note that in FIG. 6, the front side portion of the front side member 33a is omitted. The sheet magnet 53 shown in FIG. 6 is provided in the circumferential direction S across an area 50a where the metal plates 51, 52 are located and an area 50b where the metal plates 51, 52 are not located, that is, an area other than the area 50a. Region 50a is an example of a second region, and region 50b is an example of a first region.

[0035] The sheet magnet 53 has a magnetization pattern 60 that changes multiple times in the circumferential direction S. This magnetization pattern 60 is formed by combining magnets, and indicates the range of magnetic force and the boundaries and arrangement of the north and south poles. More specifically, the magnetization pattern 60 has a first magnetization pattern portion 61 formed by arranging magnetic poles of a magnet in the circumferential direction S in the region 50b where the metal plates 51, 52 are not located. In addition, the magnetization pattern 60 has a second magnetization pattern portion 62 formed by arranging magnetic poles of a magnet in the axial direction J in the regions 50a, 50b. In this way, when the magnetization pattern 60 is viewed in one direction of the circumferential direction S, the second magnetization pattern portion 62, the first magnetization pattern portion 61, and the second magnetization pattern portion 62 are arranged in this order, and are changed multiple times.

[0036] More specifically, the region 50b is provided with the first magnetization pattern portion 61 in the circumferential direction S, rather than the second magnetization pattern portion 62 in the axial direction J. As a result, even if the toner in a floating state moves from the region 50b where the metal plates 51, 52 are not located toward the outer direction Ja in the axial direction J, the movement in the axial direction J is prevented by the magnetic field of the first magnetization pattern portion 61. Also, even if the toner in a floating state moves in one direction Sa in the circumferential direction S in the first magnetization pattern portion 61, the movement in the axial direction J is prevented by the magnetic field of the second magnetization pattern portion 62.

[0037] This prevents the floating toner from leaking out of the developing device 33 (see, for example, FIG. 2). Note that the direction Sa of the circumferential direction S mentioned here includes the radial direction and is a direction other than the axial direction J. In other words, when the axial direction J is called the horizontal direction, the direction Sa can be called the vertical direction.

[0038] 6, all of the magnetization pattern 60 in the region 50b where the metal plates 51, 52 are not located is formed by arranging the magnetic poles of the sheet-shaped magnet 53 in the circumferential direction S (first magnetization pattern portion 61), but this is not limited to this. In other words, when measures against the floating toner described above are taken, it is also conceivable that at least a part of the magnetization pattern 60 in the region 50b is formed by the first magnetization pattern portion 61. In addition, the magnetization pattern 60 in the region 50a where the metal plates 51, 52 are located is formed by arranging the magnetic poles of the sheet-shaped magnet 53 in the axial direction J (second magnetization pattern portion 62), but is not limited to this, and it is also possible to form at least a part of the magnetization pattern 60 in the region 50a with the second magnetization pattern portion 62.

[0039] 6, the second magnetized pattern portion 62 of the sheet-shaped magnet 53, in which the magnetic poles of the sheet-shaped magnet 53 are arranged in the axial direction J, is arranged at the most upstream and most downstream in the circumferential direction S of the developing roll 334 and is arranged close to the metal plates 51 and 52. This prevents toner leakage in the circumferential direction S. In addition, in the case of a developing device 33 that has conventionally been equipped with a sheet-shaped magnet, by replacing it with the sheet-shaped magnet 53 of this embodiment, it is possible to prevent toner leakage and reduce the cost of design changes. Furthermore, in this embodiment, since the magnetic force of the magnet is used, the increase in starting torque is suppressed compared to the case where a sealing material such as a sponge is used to prevent toner leakage.

[0040] [Various forms of magnetization pattern 60] Next, various configurations of the magnetization pattern 60 will be described with reference to FIGS. FIG. 7 is a diagram illustrating a first example of the magnetized pattern 60. As shown in FIG. In the magnetization pattern 60, the first magnetization pattern portion 61 is formed by stacking magnet portions 61a formed in layers. Also, the second magnetization pattern portion 62 is formed by stacking magnet portions 62a formed in layers. Such magnet portions 61a, 62a correspond to the thick lines shown in FIG. 6.

[0041] 7, the magnetization pattern 60 according to the first embodiment has the above-mentioned first magnetization pattern portion 61 and second magnetization pattern portion 62. The magnet portions 61a in the first magnetization pattern portion 61 extend in the circumferential direction S and are stacked in the axial direction J. The magnet portions 62a in the second magnetization pattern portion 62 extend in the axial direction J and are stacked in the radial direction. Therefore, when the floating toner advances from the outward direction Ja through the region 50b between the metal plates 51 and 52 toward the sheet-like magnet 53, the movement in the outward direction Ja is prevented by the magnet portion 61a of the first magnetization pattern portion 61. The floating toner whose movement is prevented moves in one direction Sa, but does not leak out of the device due to the dead-end configuration or the configuration that increases the path length by the magnet portion 62a of the second magnetization pattern portion 62. Note that toner leakage to the outside of the developing device 33 is suppressed not only by the magnetization pattern 60 but also by the collection of developer by the magnetization pattern 60.

[0042] 7, the magnet portion 62a of the second magnetization pattern portion 62 contacts the magnet portion 61a of the first magnetization pattern portion 61. That is, the magnet portion 62a contacts the end portion 61b of the magnet portion 61a. This more reliably suppresses toner leakage in the axial direction J. In the first embodiment, the magnet portion 62a contacts the end 61b of the magnet portion 61a, but a non-contact configuration may be used. Even in this case, leakage to the outside of the device is suppressed by the magnetic force of the magnet portion 62a.

[0043] 7, a first magnetization pattern portion 61 having a vertical magnetization pattern by a magnet portion 61a and a second magnetization pattern portion 62 having a horizontal magnetization pattern by a magnet portion 62a are combined to form a magnetization pattern 60 in the region 50b where the metal plates 51, 52 are not located. Such magnetization pattern 60 suppresses leakage of toner suspended in the axial direction J and circumferential direction S through the region 50b.

[0044] The magnetization pattern 60 of the first embodiment changes multiple times in the circumferential direction S, and at least a portion of the region 50b is formed by arranging the magnetic poles of the magnet portion 61a in the circumferential direction S. Moreover, the magnetization pattern 60 is formed at least a portion of the region 50a by arranging the magnetic poles of the magnet portion 62a in the axial direction J. The circumferential direction S in the first embodiment is an example of a first direction, and the axial direction J is an example of a second direction.

[0045] 8 is a diagram illustrating a second embodiment of the magnetized pattern 60. In the second embodiment, the same components as those in the first embodiment are given the same reference numerals, and the description thereof may be omitted. 8, in the second embodiment, the magnet portions 62a of the second magnetization pattern portion 62 extend in the circumferential direction S and are stacked in the axial direction J, similar to the magnet portions 61a of the first magnetization pattern portion 61. In this respect, the second embodiment differs from the above-described first configuration example.

[0046] More specifically, the stacking position of the magnet portion 62a in the axial direction J is different from that of the magnet portion 61a. That is, the magnet portion 62a is not in the same position as the magnet portion 61a in the axial direction J, but is shifted in the axial direction J. Therefore, the toner in a floating state, which is prevented from moving in the outward direction Ja by the magnet portion 61a of the first magnetization pattern portion 61, is prevented from leaking outside the container by the magnetic force of the magnet portion 62a of the second magnetization pattern portion 62.

[0047] 8, a magnetization pattern 60 is formed in the region 50b where the metal plates 51, 52 are not located by combining a first magnetization pattern portion 61 having a vertical magnetization pattern with a second magnetization pattern portion 62 having a vertical magnetization pattern shifted in the axial direction J from the first magnetization pattern portion 61. Such magnetization pattern 60 suppresses leakage of toner suspended in the axial direction J and circumferential direction S through the region 50b.

[0048] The magnetization pattern 60 of the second embodiment changes multiple times in the circumferential direction S, and the magnetic poles of the magnet portions 61a are arranged in the circumferential direction S in at least a part of the region 50b where the metal plates 51, 52 are not located. More specifically, at least a portion of the magnetization pattern 60 in region 50b is formed by a first circumferential arrangement in which the magnetic poles of magnet portions 61a are arranged in the circumferential direction S. Also, at least a portion of the magnetization pattern 60 in region 50a in which the metal plates 51, 52 are located is formed by a second circumferential arrangement in which the magnetic poles of magnet portions 62a are arranged in the circumferential direction S, the second circumferential arrangement being at a different position in the axial direction J from the magnet portions 61a in the first circumferential arrangement.

[0049] FIG. 9 is a diagram illustrating a third example of the magnetized pattern 60. As shown in FIG. As shown in FIG. 9, in the third embodiment, the magnet portion 62a of the second magnetization pattern portion 62 extends in an oblique direction N that is oblique to the axial direction J. In this respect, the third embodiment differs from the first and second embodiments described above.

[0050] More specifically, the magnet portion 61a of the first magnetization pattern portion 61 and the magnet portion 62a of the second magnetization pattern portion 62 are in contact with each other. That is, the second magnetization pattern portion 62 is positioned with respect to the first magnetization pattern portion 61 so that the end portion 62b of the magnet portion 62a is connected to the end portion 61b of the magnet portion 61a. This more reliably prevents toner leakage in the axial direction J. In the third embodiment, the end 62b of the magnet portion 62a contacts the end 61b of the magnet portion 61a, but a non-contact configuration may be used. Even in this case, leakage to the outside of the device is suppressed by the magnetic force of the magnet portion 62a.

[0051] 9, a magnetization pattern 60 is formed in the region 50b where the metal plates 51, 52 are not located by combining a first magnetization pattern portion 61 having a vertical magnetization pattern with a second magnetization pattern portion 62 having a magnetization pattern in a diagonally downward direction with respect to the axial direction J. Such a magnetization pattern 60 suppresses leakage of toner suspended in the axial direction J and the circumferential direction S via the region 50b.

[0052] The magnetization pattern 60 of the third embodiment changes in the circumferential direction S a number of times. In the third embodiment, at least a part of the magnetization pattern 60 in the region 50b is formed by arranging the magnetic poles of the magnet portion 61a in the circumferential direction S, and at least a part of the magnetization pattern 60 in the region 50a is formed by arranging the magnetic poles of the magnet portion 62a in an oblique direction N different from the circumferential direction S. The oblique direction N different from the circumferential direction S here is a direction intersecting the circumferential direction S and the axial direction J. In the third embodiment, the circumferential direction S is an example of a first direction, and the oblique direction N is an example of a second direction.

[0053] FIG. 10 is a diagram illustrating a fourth example of the magnetized pattern 60. In FIG. 10, in the fourth embodiment, the magnet portions 61a of the first magnetization pattern portion 61 extend in an oblique direction N1 with respect to the axial direction J, and the magnet portions 62a of the second magnetization pattern portion 62 extend in an oblique direction N2 with respect to the axial direction J. Moreover, the oblique directions N1 and N2 extend in directions intersecting each other. Therefore, the toner in a floating state moving from the area 50b in the outward direction Ja is prevented from leaking out of the device by the magnet parts 61a and 62a.

[0054] To explain further, in the fourth embodiment, the end 61b of the magnet portion 61a in the first magnetization pattern portion 61 and the end 62b of the magnet portion 62a in the second magnetization pattern portion 62 are configured to contact each other. This more reliably prevents toner leakage in the axial direction J. In the fourth embodiment, the end 62b of the magnet portion 62a contacts the end 61b of the magnet portion 61a, but a non-contact configuration may be used. Even in this case, leakage to the outside of the device is suppressed by the magnetic force of the magnet portions 61a and 62a.

[0055] In this manner, in the fourth embodiment shown in FIG. 10, a magnetization pattern 60 is formed by combining a first magnetization pattern portion 61 having a magnetization pattern in a diagonal direction N1 that is diagonally upward with respect to the axial direction J, and a second magnetization pattern portion 62 having a magnetization pattern in a diagonal direction N2 that is diagonally downward with respect to the axial direction J, thereby suppressing leakage of toner suspended in the axial direction J and circumferential direction S via region 50b.

[0056] In the fourth embodiment, at least a portion of the magnetization pattern 60 in region 50b is formed by arranging the magnetic poles of magnet portion 61a in a direction (diagonal direction N1) that intersects the circumferential direction S and the axial direction J, and at least a portion of the magnetization pattern 60 in region 50a is formed by arranging the magnetic poles of magnet portion 62a in a direction (diagonal direction N2) that intersects the circumferential direction S and the axial direction J and also intersects the magnetic pole direction of magnet portion 61a. In the fourth embodiment, the diagonal direction N1 is an example of a first direction and an example of a first intersecting direction, and the diagonal direction N2 is an example of a second direction and an example of a second intersecting direction.

[0057] In addition, as shown in FIG. 10, the magnetization pattern 60 according to the fourth embodiment has a semicircular inner surface in which the first magnetization pattern portion 61 is arranged on the upper side and the second magnetization pattern portion 62 is arranged on the lower side. In other words, in the fourth embodiment, when the magnetization pattern 60 is divided and observed on a horizontal plane including the center point, the first magnetization pattern portion 61 is arranged on the inner surface of the upper semicircular shape and the second magnetization pattern portion 62 is arranged on the inner surface of the lower semicircular shape, but this is not limited to this. In other words, when the magnetization pattern 60 is divided and observed on a vertical plane including the center point to form two vertical semicircular shapes, the inner surface of one of the vertical semicircular shapes may be configured as shown in FIG. 10, and the inner surface of the other vertical semicircular shape may be configured upside down to the inner surface of the other vertical semicircular shape. The upside down configuration referred to here is an example in which the second magnetization pattern portion 62 is arranged on the upper side and the first magnetization pattern portion 61 is arranged on the lower side. In this arrangement example, the magnetization pattern 60 changes multiple times in the circumferential direction S.

[0058] <Additional Notes> (((1))) a developer holder in which an attraction region for attracting a developer containing a toner and a carrier is set except for an end portion, and the developer is supplied to an image holder for forming an electrostatic latent image and is held in the attraction region; a magnetic plate located in a second area excluding a first area in a circumferential direction at the end of the developer carrier; a magnet that, when combined, forms a circumferential magnetization pattern corresponding to the first range; and A developing device comprising: (((2))) The magnetization pattern changes multiple times in the circumferential direction. The developing device according to (((1))) above. (((3))) At least a part of the magnetization pattern in the first range is formed by arranging magnetic poles of a magnet in the circumferential direction of the developer carrier. The developing device according to (((1))) or (((2))) above. (((4))) At least a part of the magnetization pattern in the second area is formed by arranging magnetic poles of a magnet in the axial direction of the developer carrier. The developing device according to (((1))) or (((2))) above. (((5))) the magnets, the magnetic poles of which are arranged in the axial direction, are arranged at the most upstream and most downstream sides in the circumferential direction of the developer carrier and are arranged close to the magnetic plate; The developing device according to (((4))) above. (((6))) the magnet forming the magnetization pattern in the first area and the magnet forming the magnetization pattern in the second area are in contact with each other, The developing device according to any one of ((2))) to ((4))) above. (((7))) at least a portion of the magnetization pattern in the first area is formed by a first circumferential arrangement in which magnetic poles of magnets are arranged in the circumferential direction, At least a portion of the magnetization pattern in the second range is formed by a second circumferential array in which magnetic poles of magnets are arranged in the circumferential direction, the second circumferential array being at a different axial position from the magnets in the first circumferential array. The developing device according to (((2))) above. (((8))) at least a portion of the magnetization pattern in the first area is formed by arranging magnetic poles of a magnet in a first direction, At least a portion of the magnetization pattern in the second area is formed by arranging magnetic poles of a magnet in a second direction different from the first direction. The developing device according to (((2))) above. (((9))) the first direction is the circumferential direction of the developer carrier, the second direction is an axial direction of the developer carrier; The developing device according to (((8))) above. (((10))) the first direction is the circumferential direction of the developer carrier, the second direction is a direction intersecting the circumferential direction and an axial direction of the developer carrier; The developing device according to (((8))) above. (((11))) the first direction is a first intersecting direction intersecting the circumferential direction of the developer carrier and an axial direction of the developer carrier, The second direction is a second intersecting direction that intersects with the circumferential direction, the axial direction, and the first intersecting direction. The developing device according to (((8))) above. (((12))) an image carrier for forming an electrostatic latent image; a developing means for developing the electrostatic latent image formed on the image carrier into a toner image; a transfer means for transferring the toner image produced by the developing means onto a recording material; a fixing unit for fixing the toner image transferred onto the recording material onto the recording material; Including, The developing means is a developer holder in which an attraction region for attracting a developer containing a toner and a carrier is set except for an end portion, and the developer is supplied to an image holder for forming an electrostatic latent image and is held in the attraction region; a magnetic plate located in a second area excluding a first area in a circumferential direction at the end of the developer carrier; a magnet that, when combined, forms a circumferential magnetization pattern corresponding to the first range; and An image forming apparatus comprising:

[0059] According to the invention (((1))), it is possible to suppress the increase in costs required to prevent toner leakage, compared to the case where components are changed in order to arrange magnets and magnetic plates around the entire circumference of the end. According to the invention (((2))), the magnetization pattern changes multiple times in the circumferential direction, so that toner leakage can be prevented more reliably than in a case where the magnetization pattern does not change multiple times in the circumferential direction. According to the invention (((3))), at least a portion of the magnetization pattern in the first range can suppress an increase in starting torque compared to a case in which the magnetization pattern does not have a configuration formed by arranging magnetic poles of a magnet in the circumferential direction of the developer holder. According to the invention (((4))), at least a portion of the magnetization pattern in the second range can more reliably prevent toner leakage in the axial direction compared to a case in which the magnetization pattern is not formed by arranging the magnetic poles of a magnet in the axial direction of the developer holder. According to the invention (((5))), the magnets, whose magnetic poles are arranged in the axial direction, are arranged at the most upstream and most downstream sides of the circumferential direction of the developer holder and are also arranged closer to the magnetic plate, making it possible to more reliably prevent toner leakage in the circumferential direction compared to a case in which the magnets are not arranged at the most upstream and downstream sides of the developer holder and are arranged closer to the magnetic plate. According to the invention (((6))), toner leakage can be more reliably prevented compared to a case in which the magnets forming the magnetization pattern in the first area and the magnets forming the magnetization pattern in the second area are not in contact with each other. According to the invention (((7))), at least a portion of the magnetization pattern in the first range is formed by a first circumferential arrangement in which the magnetic poles of the magnets are arranged in the circumferential direction, and at least a portion of the magnetization pattern in the second range is formed by a second circumferential arrangement in which the magnetic poles of the magnets are arranged in the circumferential direction, and toner leakage can be prevented more reliably than when the magnetization pattern is not formed by the second circumferential arrangement in which the axial position of the magnets in the first circumferential arrangement is different. According to the invention (((8))), at least a portion of the magnetization pattern in the first range is formed by arranging the magnetic poles of a magnet in a first direction, and at least a portion of the magnetization pattern in the second range is formed by arranging the magnetic poles of a magnet in a second direction different from the first direction. This makes it possible to more reliably prevent toner leakage compared to a case in which the configuration is not included. According to the invention (((9))), the first direction is the circumferential direction of the developer holder, and the second direction is the axial direction of the developer holder, so that toner leakage can be more reliably prevented compared to a case in which the configuration is not provided. According to the invention (((10))), the first direction is the circumferential direction of the developer holder, and the second direction is a direction intersecting the circumferential direction and the axial direction of the developer holder, so that toner leakage can be more reliably prevented than in a case where the configuration is not provided. According to the invention (((11))), the first direction is a first intersecting direction that intersects with the circumferential direction of the developer holder and the axial direction of the developer holder, and the second direction is a second intersecting direction that intersects with the circumferential direction, the axial direction, and the first intersecting direction, and thus toner leakage can be prevented more reliably than in the absence of such a configuration. According to the invention (((12))), it is possible to suppress the increase in costs required to prevent toner leakage, compared to the case where components are changed in order to arrange magnets and magnetic plates around the entire circumference of the end. [Explanation of symbols]

[0060] 1...image forming apparatus, 31...photoconductor drum, 33...developing unit, 50a, 50b...area, 51, 52...metal plate, 60...magnetized pattern, 61...first magnetized pattern portion, 61a, 62a...magnet portion, 61b, 62b...end portion, 62...second magnetized pattern portion, 334...developing roll, J...axial direction, Ja...outer direction, N, N1, N2...diagonal direction, S...circumferential direction, Sa...one direction

Claims

1. a developer holder in which an attraction region for attracting a developer containing a toner and a carrier is set except for an end portion, and the developer is supplied to an image holder for forming an electrostatic latent image and is held in the attraction region; a magnetic plate located in a second area excluding a first area in a circumferential direction at the end of the developer carrier; a magnet that, when combined, forms a circumferential magnetization pattern corresponding to the first range; and A developing device comprising:

2. The magnetization pattern changes multiple times in the circumferential direction.

2. The developing device according to claim 1,

3. at least a part of the magnetization pattern in the first range is formed by arranging magnetic poles of a magnet in a circumferential direction of the developer carrier; 3. The developing device according to claim 2.

4. at least a part of the magnetization pattern in the second range is formed by arranging magnetic poles of a magnet in the axial direction of the developer carrier; 3. The developing device according to claim 2.

5. the magnets, the magnetic poles of which are arranged in the axial direction, are arranged at the most upstream and most downstream positions in the circumferential direction of the developer carrier and are arranged close to the magnetic plate; 5. The developing device according to claim 4.

6. the magnet forming the magnetization pattern in the first area and the magnet forming the magnetization pattern in the second area are in contact with each other; 3. The developing device according to claim 2.

7. at least a portion of the magnetization pattern in the first range is formed by a first circumferential arrangement in which magnetic poles of magnets are arranged in the circumferential direction, at least a portion of the magnetization pattern in the second range is formed by a second circumferential array in which magnetic poles of magnets are arranged in the circumferential direction, the second circumferential array being at a different axial position from the magnets in the first circumferential array; 3. The developing device according to claim 2.

8. at least a portion of the magnetization pattern in the first area is formed by arranging magnetic poles of a magnet in a first direction, At least a portion of the magnetization pattern in the second range is formed by arranging magnetic poles of a magnet in a second direction different from the first direction.

3. The developing device according to claim 2.

9. the first direction is the circumferential direction of the developer carrier, the second direction is an axial direction of the developer carrier; 9. The developing device according to claim 8.

10. the first direction is the circumferential direction of the developer carrier, the second direction is a direction intersecting the circumferential direction and an axial direction of the developer carrier; 9. The developing device according to claim 8.

11. the first direction is a first intersecting direction intersecting the circumferential direction of the developer carrier and an axial direction of the developer carrier, The second direction is a second intersecting direction intersecting the circumferential direction, the axial direction, and the first intersecting direction.

9. The developing device according to claim 8.

12. an image carrier for forming an electrostatic latent image; a developing means for developing the electrostatic latent image formed on the image carrier into a toner image; a transfer means for transferring the toner image produced by the developing means onto a recording material; a fixing unit for fixing the toner image transferred onto the recording material onto the recording material; Including, The developing means is a developer holder in which an attraction region for attracting a developer containing a toner and a carrier is set except for an end portion, and the developer is supplied to an image holder for forming an electrostatic latent image and is held in the attraction region; a magnetic plate located in a second area excluding a first area in a circumferential direction at the end of the developer carrier; a magnet that, when combined, forms a circumferential magnetization pattern corresponding to the first range; and An image forming apparatus comprising:

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