JP5206149B2 - Main body for magnetic field generating member, developer carrier, developing device, process cartridge, and image forming apparatus - Google Patents

Description

The present invention relates to a nonmagnetic hollow body and a relative to the nonmagnetic hollow body in order to transport the developer on the nonmagnetic hollow body used in an image forming apparatus such as a copying machine, a facsimile machine, or a printer to a latent image carrier. The present invention relates to a rotating magnetic field generating member main body, a developer carrying member having the magnetic field generating member, a developing device having the developer carrying member, a process cartridge having the developing device, and an image forming apparatus having the process cartridge.

  In general, in an electrophotographic image forming apparatus, an electrostatic latent image corresponding to image information is formed on a latent image carrier composed of a photosensitive drum or a photosensitive belt, and a developing operation is performed by a developing device. A visible image is obtained. A magnetic brush developing system is widely used for such an electrophotographic developing process. Here, when a two-component developer composed of toner and magnetic particles is used, in this magnetic brush development, the developer is magnetically adsorbed on the outer peripheral surface of the developer carrying member to form a magnetic brush, and the development region (development) In the region where a developable electric field is secured between the agent carrier and the latent image carrier), the electric field between the latent image carrier on which the electrostatic latent image is formed and the sleeve to which an electrical bias is applied Development is performed by selectively supplying and adhering toner from the magnetic brush to the latent image surface of the opposing latent image carrier.

  In recent years, attention has been paid to downsizing of developing devices, and accordingly, it is necessary to downsize developing rollers.

  However, in order to achieve high magnetic properties (usually 100 mT or more on the developing roller) and high accuracy of the developing roller main pole portion, it is difficult to realize with the conventionally used materials, roller configuration and manufacturing method. . As for the magnet material, since it is difficult to achieve a requirement with a general ferrite magnet, it is necessary to use a so-called rare earth magnet such as Ne—Fe—B for the main pole portion of the developing roller. Rare earth magnets are expensive, and as a practical development roller (magnet roller) configuration, rare earth magnets are used only for main poles that require high magnetic properties, and ferrite magnets are used for the other poles. desirable. Specifically, only the main pole part is made of a rare earth magnet block, and this is installed in the groove of a magnet roller with a groove for arranging the rare earth magnet block on the side surface. Can be minimized. Further, regarding the configuration of the small-diameter magnet roller, a shaft-integrated magnet roller, that is, a support portion in which a cylindrical support portion is provided on both ends of a cylindrical barrel portion integrally and coaxially with each other. A magnetic field generating member main body portion and a groove portion for fixing a magnet on a side surface of the body portion are provided along the cylinder axis of the body portion, and a rare earth magnet block of a main pole is disposed in the groove portion By securing the magnet volume, it is possible to secure a magnetic force other than the main developing pole even with a small magnet roller. However, depending on the diameter of the magnet roller, the depth of the groove portion for arranging the rare earth magnet block should be set deeper than the position of the support portion, that is, the bottom surface of the groove portion needs to be provided at a position deeper than the outer diameter of the column of the support portion. There may be.

  In such a magnet roller structure, the support portion becomes softer due to the shrinkage of the groove forming portion of the magnet roller body at the time of molding, which causes damage to the support portion immediately after molding, when the magnet roller is assembled or used. Cause.

  As a means for preventing such breakage, a structure in which the shaft of the support portion of the magnet roller is formed eccentric to the shaft of the body portion can be considered (Patent Document 1). At this time, the sleeve rotation is stabilized by making the flange an O-shaped groove (see FIG. 9A). However, in the case of a small-diameter magnet roller, since the diameter of the support portion is relatively larger than the diameter of the body portion, the flange cannot be formed into an annular groove shape, and a simple circular hole shape As a result, the sleeve rotation becomes unstable (see FIG. 9B).

Also, a magnet roller structure is used in which the support portion of the magnet roller is given a curvature, or the support portion is gradually narrowed by receiving a plurality of steps from the diameter of the body portion (Patent Document 2). . However, in such a structure, since the support portion having the groove side curvature becomes an edge, it is difficult to fill the resin at the time of injection molding (see FIG. 10A), and as a result, there is no curvature on the groove side, that is, In other words, the magnet roller becomes unfilled (see FIG. 10B). As a result, like the conventional product, the support portion is damaged due to the shrinkage caused at the base of the support portion and the trunk groove portion or the impact during assembly. Furthermore, since the support portion has a curvature and a step, there is a problem that the mold structure becomes complicated.
Japanese Patent Laid-Open No. 06-301293 JP 2000-114031 A

  The present invention has been made in view of the above problems, and the object of the present invention is to solve the above-mentioned problems and damage the support part due to shrinkage during molding and insufficient rigidity due to shrinkage during molding. It is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus that have high productivity and high durability by preventing damage to the support portion.

  In order to solve the above-mentioned problem, the magnetic field generating member main body according to the present invention has, as described in claim 1, a cylindrical support portion that is integral with and coaxial with the cylindrical portion at both ends of the cylindrical barrel portion. A groove portion for fixing a magnet to a side surface of the body portion is provided along an axis of a cylinder of the body portion, and a bottom surface of the groove portion is smaller than an outer diameter of the column of the support portion. In the main body for a magnetic field generating member provided at a deep position, a notch is provided on the groove side of the side surface of the support portion so as to align the base portion on the groove portion side of the support portion with the end portion of the bottom surface of the groove portion. And the cutout portion of the end surface of the support portion is less than a semicircle.

  Moreover, the magnetic field generating member main body according to the present invention is the magnetic field generating member main body according to claim 1, wherein the notch portion is formed from the side surface of the column of the support portion. It has the surface which goes to the edge part of the bottom face of the said groove part diagonally with respect to the said axis | shaft, It is characterized by the above-mentioned.

  In addition, the magnetic field generating member main body according to the present invention is the magnetic field generating member main body according to claim 1, wherein the notch portion has the same plane as the bottom surface of the groove portion. It is what has.

  According to a fourth aspect of the present invention, there is provided a developer carrier including the magnetic field generating member main body according to any one of the first to third aspects as a magnetic field generating member. A developer carrier.

  According to a fifth aspect of the present invention, there is provided a developing device comprising the developer carrying member according to the fourth aspect.

  According to a sixth aspect of the present invention, there is provided a process cartridge comprising the developing device according to the fifth aspect.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising the process cartridge according to the sixth aspect.

  According to the magnetic field generating member main body of the present invention, the notch is provided on the side of the support on the side of the groove so that the base on the groove side of the support and the end of the bottom of the groove coincide with each other. And the notch portion on the end surface of the support portion is less than a semicircle, so that the cylindrical support portion is integrally and coaxially provided at both ends of the cylindrical barrel portion, A groove portion for fixing a magnet to a side surface of the body portion is provided along an axis of a cylinder of the body portion, and a bottom surface of the groove portion is smaller than an outer diameter of the column of the support portion. By preventing the damage to the support part during use due to the damage to the support part due to shrinkage during molding and the lack of rigidity due to shrinkage during molding, even though it is the main body for the magnetic field generating member provided at a deep position, A magnetic field generating member with high productivity and high durability can be obtained.

  According to the main body part for a magnetic field generating member according to claim 2, the notch has a surface that is inclined from the side surface of the column of the support portion toward the end of the bottom surface of the groove portion obliquely with respect to the axis. As a result, the ratio of the notch in the end face of the support portion can be made small or completely unnecessary, so that the sleeve rotation is extremely stable and the support portion has high rigidity. In addition, it is possible to prevent damage to the support portion due to insufficient rigidity during use.

  According to the magnetic field generating member main body according to claim 3, since the notch has the same plane as the bottom surface of the groove, the rigidity of the support is constant in the length direction. At this time, it is possible to prevent damage to the support portion during use due to partial lack of strength.

  According to the invention described in claims 4 to 7, by preventing the support part damage due to the shrinkage at the time of molding of the main body part for the magnetic field generation member, or the support part damage due to insufficient rigidity at the time of use as the magnetic field generation member, It is possible to provide a developing device, a process cartridge, and an image forming apparatus with high productivity and high durability.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram viewed from the front of the configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the process cartridge and the developing device according to the embodiment of the present invention of the image forming apparatus shown in FIG. FIG. 3 is a model explanatory view showing the magnetic carrier 135. 4 is a cross-sectional view taken along line III-III in FIG.

  The image forming apparatus 101 forms an image of each color of yellow (Y), magenta (M), cyan (C), and black (K), that is, a color image on a recording sheet 107 as a single transfer material. . Note that units corresponding to yellow, magenta, cyan, and black colors are denoted by Y, M, C, and K at the end of the reference numerals.

  As shown in FIG. 1, the image forming apparatus 101 includes an apparatus main body 102, a paper feed unit 103, a registration roller pair 110, a transfer unit 104, a fixing unit 105, and a plurality of laser writing units 122Y, 122M, and 122C. , 122K and a plurality of process cartridges 106Y, 106M, 106C, 106K.

  The apparatus main body 102 is formed in a box shape, for example, and is installed on a floor or the like. The apparatus main body 102 includes a paper feed unit 103, a registration roller pair 110, a transfer unit 104, a fixing unit 105, a plurality of laser writing units 122Y, 122M, 122C, and 122K, and a plurality of process cartridges 106Y, 106M, and 106C. , 106K.

  A plurality of paper feed units 103 are provided in the lower part of the apparatus main body 102. The paper feed unit 103 includes a paper feed cassette 123 that can accommodate the above-described recording paper 107 in a stacked manner and can be taken in and out of the apparatus main body 102, and a paper feed roller 124. The paper feed roller 124 is pressed against the uppermost recording paper 107 in the paper feed cassette 123. The paper feed roller 124 is used to transfer the above-described uppermost recording paper 107 between a transfer belt 129 (to be described later) of the transfer unit 104 and a photosensitive drum 108 of the developing device 113 (to be described later) of the process cartridges 106Y, 106M, 106C, and 106K. Send it in between.

  The registration roller pair 110 is provided in a conveyance path of the recording paper 107 conveyed from the paper supply unit 103 to the transfer unit 104, and includes a pair of rollers 110a and 110b. The registration roller pair 110 sandwiches the recording paper 107 between the pair of rollers 110a and 110b, and the transfer unit 104 and the process cartridges 106Y, 106M, 106C, and 106K at a timing at which toner images can be superimposed on the sandwiched recording paper 107. Send between.

  The transfer unit 104 is provided above the paper feed unit 103. The transfer unit 104 includes a driving roller 127, a driven roller 128, a conveyance belt 129, and transfer rollers 130Y, 130M, 130C, and 130K. The drive roller 127 is disposed on the downstream side in the conveyance direction of the recording paper 107 and is driven to rotate by a motor or the like as a drive source. The driven roller 128 is rotatably supported by the apparatus main body 102 and is disposed on the upstream side in the conveyance direction of the recording paper 107. The conveyor belt 129 is formed in an endless annular shape and is stretched over both the driving roller 127 and the driven roller 128 described above. The transport belt 129 circulates (endless travel) counterclockwise in the drawing around the drive roller 127 and the driven roller 128 as the drive roller 127 is driven to rotate.

  The transfer rollers 130Y, 130M, 130C, and 130K sandwich the conveyance belt 129 and the recording paper 107 on the conveyance belt 129 between the photosensitive drums 108 of the process cartridges 106Y, 106M, 106C, and 106K, respectively. In the transfer unit 104, the transfer rollers 130Y, 130M, 130C, and 130K press the recording paper 107 fed from the paper supply unit 103 against the outer surface of the photosensitive drum 108 of each process cartridge 106Y, 106M, 106C, and 106K. The toner image on the photosensitive drum 108 is transferred to the recording paper 107. The transfer unit 104 sends the recording paper 107 onto which the toner image is transferred toward the fixing unit 105.

  The fixing unit 105 is provided downstream of the transfer unit 104 in the conveyance direction of the recording paper 107, and includes a pair of rollers 105a and 105b that sandwich the recording paper 107 therebetween. The fixing unit 105 presses and heats the recording paper 107 sent out from the transfer unit 104 between a pair of rollers 105a and 105b, thereby recording the toner image transferred from the photosensitive drum 108 onto the recording paper 107. Fix to paper 107.

  The laser writing units 122Y, 122M, 122C, and 122K are attached to the upper part of the apparatus main body 102, respectively. The laser writing units 122Y, 122M, 122C, and 122K correspond to one process cartridge 106Y, 106M, 106C, and 106K, respectively. The laser writing units 122Y, 122M, 122C, and 122K irradiate laser beams onto the outer surface of the photosensitive drum 108 that is uniformly charged by a later-described charging roller 109 of the process cartridges 106Y, 106M, 106C, and 106K. An electrostatic latent image is formed.

  The image forming apparatus 101 forms an image on the recording paper 107 as described below. First, the image forming apparatus 101 rotates the photosensitive drum 108 and uniformly charges the outer surface of the photosensitive drum 108 by the charging roller 109. Laser light is irradiated on the outer surface of the photosensitive drum 108 to form an electrostatic latent image on the outer surface of the photosensitive drum 108. When the electrostatic latent image is positioned in the development area 131, the developer adsorbed on the outer surface of the developing sleeve 132 of the developing device 113 is adsorbed on the outer surface of the photosensitive drum 108, and the electrostatic latent image is developed. Then, a toner image is formed on the outer surface of the photosensitive drum 108.

  In the image forming apparatus 101, the recording sheet 107 conveyed by the sheet feeding roller 124 of the sheet feeding unit 103 is transferred to the photosensitive drum 108 of the process cartridges 106Y, 106M, 106C, and 106K and the conveying belt 129 of the transfer unit 104. The toner image formed on the outer surface of the photosensitive drum 108 is transferred to the recording paper 107. The image forming apparatus 101 uses a fixing unit 105 to fix the toner image on the recording paper 107. Thus, the image forming apparatus 101 forms a color image on the recording paper 107.

  The process cartridges 106Y, 106M, 106C, and 106K are provided between the transfer unit 104 and the laser writing units 122Y, 122M, 122C, and 122K, respectively. The process cartridges 106Y, 106M, 106C, and 106K are detachable from the apparatus main body 102. The process cartridges 106Y, 106M, 106C, and 106K are arranged side by side along the conveyance direction of the recording paper 107.

  As shown in FIG. 2, the process cartridges 106Y, 106M, 106C, and 106K include a cartridge case 111, a charging roller 109 as a charging device, a photosensitive drum 108 as an electrostatic latent image carrier, and a cleaning device. A cleaning blade 112 and a developing device 113 are provided. Therefore, the image forming apparatus 101 includes at least a charging roller 109, a photosensitive drum 108, a cleaning blade 112, and a developing device 113.

  The cartridge case 111 is detachably attached to the apparatus main body 102 and accommodates a charging roller 109, a photosensitive drum 108, a cleaning blade 112, and a developing device 113. The charging roller 109 uniformly charges the outer surface of the photosensitive drum 108. The photosensitive drum 108 is disposed with a gap from a developing roller 115 (to be described later) of the developing device 113. The photosensitive drum 108 is formed in a columnar shape or a cylindrical shape that is rotatable around an axis. An electrostatic latent image is formed on the outer surface of the photosensitive drum 108 by the corresponding laser writing units 122Y, 122M, 122C, and 122K. The photosensitive drum 108 is developed by adsorbing toner onto an electrostatic latent image formed on and carried on the outer surface, and the toner image thus obtained is transferred to a recording paper 107 positioned between the conveyance belt 129. To do. The cleaning blade 112 removes the transfer residual toner remaining on the outer surface of the photosensitive drum 108 after the toner image is transferred to the recording paper 107.

  As shown in FIG. 2, the developing device 113 includes at least a developer supplying unit 114, a case 125, a developing roller 115 as a magnetic particle carrier, and a developer regulating blade 116 as a developer regulating member. Yes.

  The developer supply unit 114 includes a storage tank 117 and a pair of stirring screws 118 as stirring members. The storage tank 117 is formed in a box shape having a length substantially equal to that of the photosensitive drum 108. Further, a partition wall 119 extending along the longitudinal direction of the storage tank 117 is provided in the storage tank 117. The partition wall 119 partitions the storage tank 117 into a first space 120 and a second space 121. Moreover, both ends of the first space 120 and the second space 121 communicate with each other.

  The storage tank 117 stores the developer in both the first space 120 and the second space 121. The developer includes toner and a magnetic carrier 135. The toner is appropriately supplied to one end portion of the first space 120 on the side away from the developing roller 115 in the first space 120 and the second space 121. The toner is spherical fine particles produced by an emulsion polymerization method or a suspension polymerization method. The toner may be obtained by pulverizing a lump composed of a synthetic resin in which various dyes or pigments are mixed and dispersed. The average particle diameter of the toner is 3 μm or more and 7 μm or less. The toner may be formed by pulverization or the like.

  The magnetic carrier 135 is accommodated in both the first space 120 and the second space 121. The average particle diameter of the magnetic carrier 135 is 20 μm or more and 50 μm or less. As shown in FIG. 3, the magnetic carrier 135 includes a core material 136, a resin coat film 137 that covers the outer surface of the core material 136, and alumina particles 138 dispersed in the resin coat film 137. .

  The core 136 is made of ferrite as a magnetic material and is formed in a spherical shape. The resin coat film 137 covers the entire outer surface of the core material 136. The resin coat film 137 contains a resin component obtained by crosslinking a thermoplastic resin such as acrylic and a melamine resin, and a charge adjusting agent. This resin coat film 137 has elasticity and strong adhesive force. The alumina particles 138 are formed in a spherical shape whose outer diameter is larger than the thickness of the resin coat film 137. The alumina particles 138 are held with a strong adhesive force of the resin coat film 137. The alumina particles 138 protrude from the resin coat film 137 to the outer peripheral side of the magnetic carrier 135.

  The stirring screw 118 is accommodated in each of the first space 120 and the second space 121. The longitudinal direction of the stirring screw 118 is parallel to the longitudinal directions of the storage tank 117, the developing roller 115, and the photosensitive drum 108. The agitating screw 118 is provided so as to be rotatable around an axis, and rotates around the axis to agitate the toner and the magnetic carrier 135 and convey the developer along the axis.

  In the illustrated example, the agitation screw 118 in the first space 120 conveys the developer from one end to the other end. The agitation screw 118 in the second space 121 conveys the developer from the other end to one end.

  According to the above-described configuration, the developer supply unit 114 conveys the toner supplied to one end of the first space 120 to the other end while stirring with the magnetic carrier 135, and the second supply from the other end. It is conveyed to the other end of the space 121. The developer supply unit 114 agitates the toner and the magnetic carrier 135 in the second space 121 and supplies the toner and the magnetic carrier 135 to the outer surface of the developing roller 115 while transporting them in the axial direction.

  The case 125 is formed in a box shape, is attached to the storage tank 117 of the developer supply unit 114 described above, and covers the developing roller 115 and the like together with the storage tank 117. In addition, an opening 125 a is provided in a portion of the case 125 that faces the photosensitive drum 108.

  The developing roller 115 is formed in a cylindrical shape, and is provided between the second space 121 and the photosensitive drum 108 and in the vicinity of the opening 125a described above. The developing roller 115 is parallel to both the photosensitive drum 108 and the storage tank 117. The developing roller 115 is disposed at a distance from the photosensitive drum 108.

  The developer regulating blade 116 is provided at the end of the developing device 113 near the photosensitive drum 108. The developer regulating blade 116 is attached to the case 125 described above with a space from the outer surface of the developing sleeve 132. The developer regulating blade 116 scrapes off the developer on the outer surface of the developing sleeve 132 exceeding the desired thickness into the storage tank 117, and the developer on the outer surface of the developing sleeve 132 conveyed to the developing region 131. To the desired thickness.

  The developing device 113 sufficiently agitates the toner and the magnetic carrier 135 by the developer supplying unit 114 and adsorbs the agitated developer to the outer surface of the developing sleeve 132 by the fixed magnetic pole. In the developing device 113, the developing sleeve 132 rotates, and the developer adsorbed by the plurality of fixed magnetic poles is conveyed toward the developing region 131. The developing device 113 adsorbs the developer having a desired thickness by the developer regulating blade 116 to the photosensitive drum 108. Thus, the developing device 113 carries the developer on the developing roller 115 and transports it to the developing area 131 to develop the electrostatic latent image on the photosensitive drum 108 to form a toner image.

  Then, the developing device 113 releases the developed developer toward the storage tank 117. Further, the developed developer stored in the storage tank 117 is sufficiently stirred again with another developer in the second space 121 and used for developing the electrostatic latent image on the photosensitive drum 108. .

  The developing roller 115 will be described with reference to FIGS.

  As shown in FIG. 4, the developing roller 115 includes a magnet roller 133 as a magnetic field generating member and a developing sleeve 132.

  The magnet roller 133 is accommodated (enclosed) in the developing sleeve 132. As shown in FIG. 5, the magnet roller 133 is provided integrally with a cylindrical body portion having a groove portion for fixing a magnet along a cylinder axis on a side surface, and at both ends of the body portion. A columnar magnetic field generating means 140 that is a main body portion for a magnetic field generating member that is formed of a support portion and a rare earth magnet block 141 as a magnet disposed inside the groove of the groove-shaped member.

  The rare earth magnet block 141 for forming the developing main pole is a rectangular parallelepiped magnet block having a width of 2.0 mm, a height of 2.4 mm, and a length of 328 mm, which is manufactured by compression magnetic field molding and extends in the developing roller axial direction. In order to obtain narrow and high magnetic properties, many of the above-mentioned rare earth magnets such as Ne (Ne · Fe · B, etc.) or Sm (Sm · Co, Sm · Fe · N, etc.) or their magnet powder are used. A plastic magnet or a rubber magnet mixed with the same polymer compound as can be used.

  The columnar magnetic field generating means 140 includes a body portion that forms magnetic characteristics other than the developing main pole having a diameter of 10 mm and a length of 328 mm, and a diameter of 6 mm and a length of 15 mm coaxially with the body portion at both ends of the body portion. The support part is manufactured by integral molding.

  As a material, a so-called plastic magnet or rubber magnet in which a polymer compound is mixed with magnetic powder is often used. Sr ferrite or Ba ferrite is used as the magnetic powder, and PA (polyamide) material such as 6PA or 12PA is used as the polymer compound, EEA (ethylene / ethyl copolymer) or EVA (ethylene / vinyl copolymer). Ethylene compounds, chlorine materials such as CPE (chlorinated polyethylene), and rubber materials such as NBR can be used.

  FIG. 6A to FIG. 6F schematically show examples of the magnetic field generating member main body according to the present invention.

  As shown in FIG. 6A, which is a side view, and FIG. 6B, which is a front view, the magnetic field generating member main body 140a is formed integrally with the barrel 140a1 at both ends of a cylindrical barrel 140a1. The cylindrical support portions 140a2 are coaxially provided, the groove portions 140a4 for fixing the magnets to the side surfaces of the trunk portion 140a1 are provided along the cylinder axis of the trunk portion 140a1, and the bottom surface 140a5 of the groove portion 140a4. Is a magnetic field generating member main body provided at a position deeper than the outer diameter of the support portion 140a2, and further, a notch portion for matching the base portion on the groove portion 140a4 side of the support portion 140a2 and the end portion of the groove portion 140a4. 140a3 is provided on the side of the groove 140a4 on the side surface of the support 140a2. The notch 140a3 has a surface that is inclined from the cylindrical side surface of the support portion 140a2 toward the end of the bottom surface of the groove portion 140a4 obliquely with respect to the axis.

  Further, the notch 140a3 does not exist on the end surface of the support 140a2.

  On the other hand, the magnetic field generating member main body 140b is provided with cylindrical support portions 140b2 that are integral with and coaxial with the barrel portion 140b1 at both ends of the cylindrical barrel portion 140b1, and magnets are provided on the side surfaces of the barrel portion 140b1. A magnetic field generating member main body portion in which a groove portion 140b4 for fixing is provided along the cylindrical axis of the body portion 140b1 and a bottom surface 140b5 of the groove portion 140b4 is provided at a position deeper than the outer diameter of the support portion 140b2. Further, a notch 140b3 is provided on the side of the support 140b2 on the side of the groove 140b4 so that the base of the support 140b2 on the side of the groove 140b4 and the end of the groove 140b4 are aligned. The notch 140b3 has the same plane as the bottom surface 140b5 of the groove 140b4.

  Furthermore, the notch part 140b3 in the end surface of the support part 140a2 is less than a semicircle.

  Furthermore, when the bottom surface of the groove is deep, it is easy to cope with such a configuration as the magnetic field generating member main body 140c. As shown in FIG. 6 (e) which is a side view and FIG. 6 (f) which is a front view, the magnetic field generating member main body 140c is integrated with the barrel 140c1 at both ends of a cylindrical barrel 140c1. Coaxially cylindrical support portions 140c2 are respectively provided, groove portions 140c4 for fixing magnets are provided on the side surfaces of the trunk portion 140c1 along the cylinder axis of the trunk portion 140c1, and a bottom surface 140c5 of the groove portion 140c4 is provided. The magnetic field generating member main body provided at a position deeper than the outer diameter of the support portion 140c2, and further, a notch portion 140c3 for matching the base portion on the groove portion 140c4 side of the support portion 140c2 with the end portion of the groove portion 140c4. Is provided on the side of the support 140c2 on the side of the groove 140c4. The notch 140b3 has the same plane as the bottom surface 140b5 of the groove 140b4, but further, the notch 140b3 at the end surface of the support part 140c2 is formed by an inclined surface facing the cylindrical side surface of the support part 140c2. Is less than half a yen.

  In this way, the cutout portion is less than a semicircle on the end surface of the support portion, thereby preventing damage due to insufficient strength of the support portion, and as shown in the model cross-sectional view of FIG. As shown in the model cross-sectional view of FIG. 8 (a), it is prevented in advance that the shaft is displaced due to the rotation of the sleeve as shown in FIGS. 7 (b) and 7 (c). When the sleeve is held by the flange, even if the sleeve rotates, the shaft center shake does not occur as shown in FIG.

  In these magnetic field generating member main body portions 140a to 140c, the notch portion provided in the support portion causes the base portion on the groove portion side of the support portion to coincide with the end portion of the bottom surface of the groove portion. Damage to the support can be prevented.

  The developing sleeve 132 is made of a non-magnetic material, and includes (accommodates) a magnet roller 133 and is provided so as to be rotatable around an axis. The developing sleeve 132 is rotated so that the inner peripheral surface thereof is sequentially opposed to the fixed magnetic pole. The developing sleeve 132 is made of aluminum, stainless steel (SUS), or the like. Aluminum is excellent in terms of workability and lightness. When using aluminum, it is preferable to use A6063, A5056, and A3003. When using SUS, it is preferable to use SUS303, SUS304, and SUS316.

  The shape of the magnetic field generating member main body portions 140a to 140c according to the present invention provided with notches for matching the base portion on the groove portion side of the support portion and the end portion of the bottom surface of the groove portion shown in a model in FIG. The magnetic field generating member main body was actually fabricated.

  That is, injection molding was performed using a compound of anisotropic Sr ferrite and polyamide PA12 (manufactured by Toda Kogyo Co., Ltd.) at a resin temperature of 300 ° C. and applying a magnetic field of 0.6 T in one direction perpendicular to the bottom surface of the groove. After that, demagnetization is performed by applying a 0.1 T magnetic field in the direction opposite to that at the time of injection, and the body portion has an outer diameter of 10 mm, a total length of 328 mm, a width of 3 mm, and a depth of 2.7 mm (140a and 140b, 140c is the depth). 10 mm), and a 328 mm long groove, and 10 samples of each of the magnetic field generating member main bodies each having a support portion having an outer diameter of 6 mm and a length of 15 mm coaxially provided at both ends of the body portion. .

  Further, for comparison, ten samples of the magnetic field generating member main body according to the prior art were prepared under the same conditions (the depth of the groove portion was 2.7 mm) except that the notch portion was not provided.

  A load of 2N is applied at a position of 13 mm from the base portion to the end portion of both support portions, with the inner side of both ends of the body portion on the side opposite to the groove forming side as the fulcrum of each of the magnetic field generating member main body portions. Added (generally, the magnetic attraction force in the upstream region of the doctor deflects the developing roller in a range of 0.6 N (doctor pole magnetic flux density 40 mT) to 1.2 N (doctor pole magnetic flux density 60 mT). 2N was selected as the load value provided.)

  At this time, none of the magnetic field generating member main bodies according to the present invention was broken in 10 samples, but in the magnetic field generating member main body having no notch according to the prior art, 9 out of 10 samples. Breakage occurred in the samples (3 when molded, 6 when loaded).

It is model sectional drawing which shows the manufacturing method of the endless belt of this invention. FIG. 3 is a model diagram illustrating an intermediate transfer unit according to the present invention. FIG. 3 is an explanatory diagram of a model showing a magnetic carrier 135. It is a model diagram which shows the structure of a developing roller. It is a model sectional view showing the configuration of the developing roller. It is a figure which shows the main-body parts 140a-140c for magnetic field generation members which concern on this invention. (A) The side view of the main-body part 140a for magnetic field generation members. (B) The front view of the main-body part 140a for magnetic field generation members. (C) The side view of the main-body part 140b for magnetic field generation members. (D) The front view of the main-body part 140b for magnetic field generation members. (E) The side view of the main-body part 140c for magnetic field generation members. (F) The front view of the main-body part 140c for magnetic field generation members. It is a model figure which shows that an axial center blurring arises. It is a model figure which shows that an axial center shake does not occur in the magnet roller which concerns on this invention. It is a model figure for demonstrating the problem of a prior art. It is a model figure for demonstrating the problem of a prior art.

Explanation of symbols

140a, 140b, 140c Magnetic field generating member main body 140a1, 140b1, 140c1 body 140a2, 140b2, 140c2 support part 140a3, 140b3, 140c3 notch part 140a4, 140b4, 140c4 groove part 140a5, 140b5, 140c5 groove part Bottom

Claims (7)

Cylindrical support portions that are integral with and coaxial with the cylindrical portion are provided at both ends of the cylindrical cylindrical portion, respectively, and a groove portion for fixing a magnet to the side surface of the cylindrical portion is an axis of the cylindrical portion of the cylindrical portion. And the bottom surface of the groove portion is provided at a position deeper than the outer diameter of the columnar column of the support portion.
A notch portion is provided on the side of the support portion on the groove portion side in order to match the base portion on the groove portion side of the support portion and the bottom end portion of the groove portion, and
The main body part for a magnetic field generating member, wherein the cutout part on the end face of the support part is less than a semicircle.   2. The magnetic field generation according to claim 1, wherein the notch has a surface that is inclined from the side surface of the column of the support portion toward the end of the bottom surface of the groove portion obliquely with respect to the axis. Main part for members.   2. The magnetic field generating member main body according to claim 1, wherein the notch has the same plane as the bottom surface of the groove.   A developer carrier comprising the magnetic field generating member main body according to any one of claims 1 to 3 as a magnetic field generating member.   A developing device comprising the developer carrying member according to claim 4.   A process cartridge comprising the developing device according to claim 5.   An image forming apparatus comprising the process cartridge according to claim 6.

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