JP2011174960A - Developing device and image forming apparatus and process cartridge incorporating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device that prevents toner from scattering outside the developing device in the case of using a developer carrier that has a plurality of recesses formed in its outer periphery, and to provide an image forming apparatus and a process cartridge that have this developing device. <P>SOLUTION: A magnet roller 113 includes conveyance poles P2 and P3. A predetermined gap is provided between an inner wall of the casing 125 and the outer circumferential surface of the development sleeve 132 at a position downstream of the opening of a case 125 in the rotating direction of the development sleeve 132. The developing sleeve 132 is provided with a plurality of recesses 139 on its outer periphery so as to be interspatially distributed. An arrangement pitch Pc of the adjacent recesses 139 in the circumferential direction of the developing sleeve 132 is shorter than a length WGP3 that is equal to half the width of the magnetic flux density of the pole P3 on the outer periphery of the developing sleeve 132 in the direction perpendicular to the longitudinal direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device that develops a latent image on an image carrier using a developer containing toner, and an image forming apparatus such as a copying machine, a facsimile, and a printer, and a process cartridge including the developing device. .

  Conventionally, as this type of image forming apparatus, an apparatus using two-component magnetic brush development is known. In the two-component magnetic brush development, the developer adsorbed by the electrostatic force on the carrier in which the toner is made of magnetic powder is conveyed to a development area facing the image carrier, and the electrostatic latent image formed on the image carrier is developed. Then, a developer carrier for forming a toner image is used.

  The developer carrying member has, for example, a cylindrical developing sleeve, and a magnetic field generating means (for example, a magnet roller) that forms a magnetic field so as to cause the developer to rise on the surface of the developing sleeve. Have. When the developer is spiked, the carrier constituting the developer is spiked on the developing sleeve so as to follow the lines of magnetic force generated by the magnet roller, and charged toner adheres to the carrier. The magnet roller has a plurality of magnetic poles, and the magnets forming the respective magnetic poles are formed in a molded body such as a rod shape, and in particular, a developer is applied to a portion corresponding to the developing region portion of the developing sleeve surface. It has a developing main pole that makes it stand up. The developer that has risen can be moved in the circumferential direction by rotating at least one of the developing sleeve and the magnet roller. In general, in order to facilitate transport of the developer, a groove or irregular unevenness (unevenness due to sandblasting, bead blasting, or the like) is provided on the surface of the developing sleeve. In particular, in color copiers and printers, developing sleeves with irregular irregularities such as sand blasting and bead blasting have become the mainstream because of superior image quality. Such roughening processing such as grooving and sandblasting is performed in order to prevent the occurrence of a decrease in image density caused by the developer slipping and stagnation on the surface of the developing sleeve rotating at high speed.

  However, if the toner and the carrier are not sufficiently adsorbed, the toner may be released from the carrier and scattered outside the developing device in the developing region or in the path for transporting and collecting the developer from the developing device to the developing region. is there. As a case where the toner and the carrier are not sufficiently adsorbed, there are insufficient charging when the toner and the carrier are mixed and insufficient charging due to deterioration of the developer. In particular, in an image forming apparatus configured so that the developing device is detachable, it is desirable that toner scattering is as small as possible on the front side in the attaching / detaching direction of the developing device, which is directly operated and checked by a serviceman or a user.

  In order to suppress the toner scattering, the developing device is provided with a gap called a casing gap on the developing sleeve and the inner wall of the developing device. The casing gap is a gap between the surface of the developing sleeve near the opening through which the developer passes through the developing region and the inner wall of the developing device, and is provided to face the magnetic pole of the magnet roller. Since the developer rises along the lines of magnetic force generated by the magnet roller, when the agent that has risen through the casing gap passes along with the rotation of the developing sleeve, a suction air flow is generated inside the developing device, and the outside of the developing device The toner can be prevented from scattering.

  As a developing sleeve used in the developing device, Patent Document 1 discloses a developing sleeve having a plurality of concave portions provided on the surface at regular intervals. This developing sleeve can maintain the same agent density on the developing sleeve as the developing sleeve whose surface is provided with irregular irregularities such as sandblasting, and is similar to the developing sleeve whose surface is provided with grooves. Has developer conveying power.

  However, when a developing sleeve having a plurality of concave portions provided at regular intervals on the surface as disclosed in Patent Document 1 is used, the developer that stands up on the developing sleeve passes through the casing gap. In this case, there is a possibility that the toner may be scattered outside the developing device due to insufficient suction air flow into the developing device.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent toner scattering to the outside of the developing device when a developer carrier having a plurality of recesses formed on the outer peripheral surface is used. An image forming apparatus and a process cartridge including the developing device.

In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that a magnetic field generating means is disposed inside a sleeve-like hollow body made of a non-magnetic member and capable of being driven to rotate. A developer carrying member for carrying and conveying a two-component developer containing a magnetic carrier and toner on the surface, a developer containing unit for containing the two-component developer carried on the developer carrying member, A developer regulating member that regulates the layer thickness of the two-component developer carried on the developer carrying body, the developer carrying body, the developer containing portion, and a housing that houses the developer regulating member; The two-component developer carried on the developer carrying member by the magnetic force of the magnetic field generating means from within the developer containing portion is regulated by the developer regulating member, and then the opening provided in the housing To expose a part of the outer peripheral surface of the hollow body to carry a latent image A developing device that passes the developing area opposite to the developing container and returns the developing area to the developer container, wherein the magnetic field generating means is a position at which the two-component developer that has passed through the developing area is separated from the developer carrier. A magnetic field generating member having a magnetic pole for conveyance for generating a magnetic force to be conveyed up to the downstream of the opening of the casing in the rotation direction of the hollow body, wherein the two-component developer is the developer. The hollow body is configured to have a predetermined gap between the inner wall of the housing and the outer peripheral surface of the hollow body until a position where the hollow body is separated from the carrier, and the hollow body includes a plurality of recesses on the outer peripheral surface. Are distributed so as to be spaced apart from each other, and the arrangement pitch of the recesses adjacent to each other in the circumferential direction of the hollow body is orthogonal to the longitudinal direction of the magnetic field generating member on the outer circumferential surface of the hollow body To the half-width of magnetic flux density It is characterized in that it has set shorter than the length of the portion.
According to a second aspect of the present invention, in the developing device of the first aspect, the recesses adjacent to each other in the circumferential direction of the hollow body are provided so as to be shifted from each other in the rotation axis direction of the hollow body. The amount of displacement of the recess in the axial direction is less than or equal to the length of the recess in the rotation axis direction.
According to a third aspect of the present invention, in the developing device of the first or second aspect, the image forming apparatus body is configured to be detachable in the direction of the rotation axis of the hollow body, and the direction of the rotation axis of the hollow body. The developing device itself is configured to generate an airflow from the near side in the attaching / detaching direction to the far side.
According to a fourth aspect of the present invention, in the developing device according to the third aspect, the arrangement pitch of the recesses in the circumferential direction of the hollow body is smaller on the back side than on the front side in the attaching / detaching direction of the developing device itself. It is what.
According to a fifth aspect of the present invention, in the developing device according to the third or fourth aspect, the concave portion provided on the outer peripheral surface of the hollow body has an oval or elliptical shape, and the longitudinal direction of the concave portion is The angle has an angle with respect to the rotation axis direction of the hollow body, and the air flow is generated with respect to the rotation axis direction of the hollow body from the front side to the back side in the attaching / detaching direction of the developing device itself. Is set.
According to a sixth aspect of the present invention, a latent image carrier and a two-component developer comprising a magnetic carrier and a toner are conveyed to a development area facing the latent image carrier to form a latent image on the latent image carrier. A developing device that attaches and develops the toner is integrally supported, and the toner image obtained by the development by the developing device is finally transferred from the latent image carrier onto the recording material, so that In a process cartridge that is detachable from an image forming apparatus for forming an image, the developing device according to any one of claims 1 to 5 is used as the developing device.
According to a seventh aspect of the present invention, a latent image carrier and a two-component developer comprising a magnetic carrier and a toner are conveyed to a development area facing the latent image carrier to form a latent image on the latent image carrier. A developing device that attaches and develops the toner is integrally supported, and the toner image obtained by the development by the developing device is finally transferred from the latent image carrier onto the recording material, so that An image forming apparatus including a process cartridge that is detachable from an image forming apparatus for forming an image on the image forming apparatus, wherein the process cartridge according to claim 6 is used as the process cartridge.
The invention according to claim 8 is the image forming apparatus according to claim 7, wherein at least the polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant and a release agent are dispersed in an organic solvent. The toner material liquid is a toner obtained by performing at least one of crosslinking and extension reaction in an aqueous medium.

  In the present invention, the magnetic carrier constituting the developer spikes in the concave portion provided on the outer peripheral surface of the hollow body so as to follow the lines of magnetic force generated by the magnetic field generating member, and the toner adheres to the spiked magnetic carrier. The rise of the developer occurs at a portion corresponding to the half-value width of the magnetic flux density on the outer peripheral surface of the hollow body. Here, since the arrangement pitch of the recesses adjacent to each other in the circumferential direction of the hollow body is set to be shorter than the length of the portion corresponding to the half-value width of the magnetic flux density on the outer circumferential surface of the hollow body, There are at least two recesses in the portion corresponding to the half-width of the magnetic flux density, and the developer carried in these recesses is prominent. When the developer carried in these recesses rises, a predetermined gap between the outer peripheral surface of the hollow body and the inner wall of the housing is partitioned, and the air that exists in the partitioned gap by rotation of the hollow body. Is transported to a developer container inside the developing device. When air is conveyed to the developer accommodating portion, a negative pressure is generated in the gap, and external air flows from the opening of the developing device to generate a suction airflow. Therefore, even if the insufficiently charged toner is released in the vicinity of the opening of the developing device, the toner is sucked into the suction airflow and carried into the developing device and is not scattered outside the developing device.

  According to the present invention, when a developer carrying member having a plurality of concave portions formed on the outer peripheral surface is used, there is an excellent effect that toner scattering to the outside of the developing device can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram viewed from the front of a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a process cartridge used in the image forming apparatus in FIG. 1. Sectional drawing which follows the III-III line | wire in FIG. FIG. 2 is a perspective view of a developing sleeve of the image forming apparatus in FIG. 1. Explanatory drawing which expand | deploys and shows typically the outer surface of the image development sleeve of FIG. (A) is explanatory drawing which expands and shows a part of outer surface of the image development sleeve of FIG. 5 typically. (B) is sectional drawing which follows the VIB-VIB line | wire in Fig.6 (a). (C) is sectional drawing which follows the VIC-VIC line | wire in Fig.6 (a). Explanatory drawing which expands and shows a part of outer surface of the developing sleeve of FIG. FIG. 5A is a side view showing a schematic configuration of a surface treatment apparatus that performs cutting on the outer surface of the developing sleeve of FIG. 4. (B) is sectional drawing which follows the VIIIB-VIIIB line | wire in Fig.8 (a). FIG. 9C is an enlarged side view showing the end mill of FIG. (D) is the front view of the front-end | tip of the end mill of FIG.8 (c). (A) is explanatory drawing which expands and shows typically a part of outer surface of the modification of the developing sleeve of Fig.6 (a). (B) is sectional drawing which follows the IXB-IXB line | wire in Fig.9 (a). (C) is sectional drawing which follows the IXC-IXC line | wire in Fig.9 (a). Sectional drawing which expands and shows a part of FIG.9 (b). The side view which expands and shows the end mill for forming the dent provided in the outer surface of the image development sleeve of FIG. Sectional drawing which shows the modification of the dent formed in the outer surface of the image development sleeve of FIG.6 (b). Sectional drawing which shows the other modification of the dent formed in the outer surface of the image development sleeve of FIG.6 (b). FIG. 6 is an explanatory view schematically showing an outer surface of a modified example of the developing sleeve of FIG. FIG. 6 is an explanatory diagram schematically showing an outer surface of another modification of the developing sleeve of FIG. (A) is explanatory drawing which expand | deploys and shows typically the outer surface of the further another modification of the image development sleeve of FIG. FIG. 17B is an enlarged side view showing the end mill for forming the recess shown in FIG. FIG. 2 is a schematic configuration diagram illustrating an example of a developing device. FIG. 3 is an enlarged view of the vicinity of the P2 pole and P3 pole of the developing device. FIG. 6 is an enlarged view of the vicinity of the P2 pole and the P3 pole showing a comparative example for explaining toner scattering. The perspective view which expanded a part of developing sleeve. The perspective view which looked at the developing device from the longitudinal direction. (A) is a perspective view of the developing sleeve in which the longitudinal direction of the recess has an oblique angle with respect to the rotation axis direction of the developing sleeve. FIG. 22B is an enlarged view of a portion A in FIG.

Hereinafter, embodiments 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 developing device according to an embodiment of the present invention of the image forming apparatus shown in FIG. 3 is a cross-sectional view taken along line III-III in FIG. 4 is a perspective view of a developing sleeve of the developing device shown in FIG. FIG. 5 is a development view of the outer surface of the developing sleeve shown in FIG.

  The image forming apparatus 101 prints 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 (see FIG. 1). The image forming portion of a tandem type color copying machine using the intermediate transfer belt 129 formed in (1). The units corresponding to the colors of yellow, magenta, cyan, and black are indicated by adding 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 feeding unit 103, a registration roller pair 110, an intermediate transfer unit 104, a paper transfer roller 126, a fixing unit 105, and a plurality of laser writing. At least a unit 122 (122Y, 122M, 122C, 122K) and a plurality of process cartridges 106Y, 106M, 106C, 106K are provided.

  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 sends out the top recording paper 107 described above to the registration roller pair 110.

  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 paper transfer roller 126, 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 sends out the sandwiched recording paper 107 at a timing at which the recording paper 107 can be transferred onto the transfer paper.

  The intermediate transfer unit 104 is provided above the process cartridges 106Y, 106M, 106C, and 106K. The intermediate transfer unit 104 includes a driving roller 128, a driven roller 127, an intermediate transfer belt 129, and intermediate transfer rollers 130Y, 130M, 130C, and 130K. The drive roller 128 is disposed at a position opposite to the paper transfer roller 126 and is rotationally driven by a motor as a drive source. The driven roller 127 is rotatably supported by the apparatus main body 102. The intermediate transfer belt 129 is formed in an endless annular shape and is stretched over both the driving roller 128 and the driven roller 127 described above. The intermediate transfer belt 129 circulates (endless travel) around the driving roller 128 and the driven roller 127 described above counterclockwise in the figure as the driving roller 128 is rotationally driven.

  The intermediate transfer rollers 130Y, 130M, 130C, and 130K are disposed so that the intermediate transfer belt is sandwiched between the process cartridges 106Y, 106M, 106C, and 106K at positions facing the photosensitive drum 108, respectively. The intermediate transfer unit 104 superimposes each color toner image formed by the process cartridges 106Y, 106M, 106C, and 106K as a color toner image on the intermediate transfer belt 129 by the transfer rollers 130Y, 130M, 130C, and 130K, and transfers the paper. The color toner image is conveyed to the roller 126 and transferred to the recording paper 107 by the paper transfer roller. The paper transfer roller 126 sends the recording paper 107 onto which the toner image has been transferred toward the fixing unit 105.

  The fixing unit 105 includes a pair of rollers 105 a and 105 b that are provided downstream in the conveyance direction of the recording paper 107 transferred by the paper transfer roller 126 and sandwich the recording paper 107 therebetween. The fixing unit 105 fixes the toner image transferred onto the recording paper 107 onto the recording paper 107 by pressing and heating the recording paper 107 sent from the paper transfer roller 126 between the pair of rollers 105a and 105b. Let

  The laser writing unit 122 (122Y, 122M, 122C, 122K) is attached to the lower part of the process cartridge 106Y, 106M, 106C, 106K. The laser writing unit 122 (122Y, 122M, 122C, 122K) corresponds to one process cartridge 106Y, 106M, 106C, 106K, respectively. The laser writing unit 122 (122Y, 122M, 122C, 122K) irradiates the outer surface of the photosensitive drum 108 uniformly charged by a later-described charging roller 109 of the process cartridge 106Y, 106M, 106C, 106K with laser light. An electrostatic latent image is formed.

  The process cartridges 106Y, 106M, 106C, and 106K are provided between the intermediate transfer unit 104 and the laser writing unit 122 (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 intermediate transfer belt 129.

  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 (also referred to as an image carrier) 108, and a cleaning device as a cleaning device. A blade 112 and a developing device 113 are provided.

  The cartridge case 111 is detachable from 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 cylindrical shape that is rotatable about an axis. An electrostatic latent image is formed on the outer surface of the photosensitive drum 108 by the corresponding laser writing unit 122 (122Y, 122M, 122C, 122K). The photosensitive drum 108 is developed by adhering toner to an electrostatic latent image formed and carried on the outer surface, and transfers the toner image thus obtained onto the intermediate transfer belt 129. The cleaning blade 112 removes the transfer residual toner remaining on the outer surface of the photosensitive drum 108 after transferring the toner image to the intermediate transfer belt 129.

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

  The developer supply unit 114 includes a storage tank 117 as a developer storage unit 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 contains toner and a magnetic carrier (also referred to as magnetic powder). The toner is appropriately supplied by the toner replenishing device 108 to one end 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. As the toner, a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent is used in an aqueous medium. A toner obtained by performing one of these is preferred.

  The magnetic carrier is accommodated in both the first space 120 and the second space 121. The average particle size of the magnetic carrier is 20 μm or more and 50 μm or less.

  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 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, and from the other end to the second space. The other end of 121 is conveyed. The developer supply unit 114 agitates the toner and the magnetic carrier in the second space 121 and supplies them to the outer surface of the developing roller 115 while conveying the toner 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. A space between the developing roller 115 and the photosensitive drum 108 forms a developing region 131 in which the toner of the developer is attracted to the photosensitive drum 108 to develop the electrostatic latent image and obtain a toner image. In the developing area 131, the developing roller 115 and the photosensitive drum 108 face each other.

  As shown in FIGS. 2 and 3, the developing roller 115 includes a cored bar 134, a cylindrical magnet roller (also referred to as a magnet body) 133, and the above-described cylindrical developing sleeve 132. The core metal 134 is arranged in parallel with the longitudinal direction of the photosensitive drum 108 in the longitudinal direction, and is fixed to the case 125 without rotating.

  The magnet roller 133 is made of a magnetic material, is formed in a cylindrical shape, and is attached with a plurality of fixed magnetic poles (not shown). The magnet roller 133 is fixed to the outer periphery of the core bar 134 without rotating around the axis.

  The fixed magnetic pole is a long and rod-shaped magnet, and is attached to the magnet roller 133. The fixed magnetic pole extends along the longitudinal direction of the magnet roller 133, that is, the developing roller 115, and is provided over the entire length of the magnet roller 133. The magnet roller 133 having the above-described configuration is accommodated (enclosed) in the developing sleeve 132.

  One fixed magnetic pole is opposed to the agitating screw 118 described above. The one fixed magnetic pole serves as a pumping magnetic pole, and generates a magnetic force on the outer surface of the developing sleeve 132, that is, the developing roller 115, so that the developer in the second space 121 of the storage tank 117 is removed from the developing sleeve 132. Adsorb to the surface.

  The other fixed magnetic pole is opposed to the photosensitive drum 108 described above. The fixed magnetic pole forms a developing magnetic pole, and generates a magnetic force on the outer surface of the developing sleeve 132, that is, the developing roller 115, thereby forming a magnetic field between the developing sleeve 132 and the photosensitive drum 108. The fixed magnetic pole forms a magnetic brush by the magnetic field so that the developer toner adsorbed on the outer surface of the developing sleeve 132 is transferred to the photosensitive drum 108.

  At least one fixed magnetic pole is provided between the pumping magnetic pole and the developing magnetic pole. The at least one fixed magnetic pole generates a magnetic force on the outer surface of the developing sleeve 132, that is, the developing roller 115, conveys the developer before development toward the photosensitive drum 108, and photosensitive the developed developer. It is conveyed from the body drum 108 into the storage tank 117.

  When the developer is adsorbed to the outer surface of the developing sleeve 132, the fixed magnetic pole described above is erected on the outer surface of the developing sleeve 132 by superimposing a plurality of magnetic carriers of the developer along the magnetic force lines generated by the fixed magnetic pole. Let them stand. In this way, a state in which a plurality of magnetic carriers are stacked on the outer surface of the developing sleeve 132 along the lines of magnetic force is standing on the outer surface of the developing sleeve 132. As a result, the toner described above is adsorbed to the magnetic carrier. That is, the developing sleeve 132 attracts the developer to the outer surface by the magnetic force of the magnet roller 133.

  As shown in FIG. 4, the developing sleeve 132 is formed in a cylindrical shape. The developing sleeve 132 includes (accommodates) a magnet roller 133 and is provided so as to be rotatable around the 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 a nonmagnetic material such as aluminum alloy, brass, stainless steel (SUS), or conductive resin. The developing sleeve 132 is roughened on the outer surface by the surface treatment apparatus 1 (shown in FIG. 8).

  Aluminum alloys are excellent in terms of workability and lightness. When an aluminum alloy is used, it is preferable to use A6063, A5056, and A3003. When using SUS, it is preferable to use SUS303, SUS304, and SUS316. In the illustrated example, the developing sleeve 132 is made of an aluminum alloy.

  The outer diameter of the developing sleeve 132 is about 18 mm in this embodiment. The length of the developing sleeve 132 in the axial (axial center) direction is desirably about 300 mm to 350 mm when the maximum paper size of the image forming apparatus is A3.

  Further, as shown in FIGS. 4, 5, 6 (a) and 7, the outer surface of the developing sleeve 132 is provided with a large number of recesses 139 as recesses having an elliptical shape in plan view. Of course, the recesses 139 are formed in a concave shape on the outer surface of the developing sleeve 132, and a large number (a plurality) are regularly arranged on the outer surface of the developing sleeve 132 so as not to overlap each other. In the present embodiment, the fact that the intervals between the recesses 139 adjacent to each other in the circumferential direction and the longitudinal direction of the developing sleeve 132 are constant is referred to as the regular arrangement of the recesses 139. That is, the interval between the recesses 139 adjacent to each other in the circumferential direction and the longitudinal direction of the developing sleeve 132 is constant.

  Further, the recess 139 is arranged in a state where the longitudinal direction thereof is along the longitudinal direction of the developing sleeve 132. That is, the recess 139 is arranged such that its longitudinal direction is parallel or substantially parallel to the longitudinal direction of the developing sleeve 132. In the illustrated example, the longitudinal direction of the recess 139 is slightly inclined with respect to the longitudinal direction of the developing sleeve 132 and is arranged substantially in parallel. In this embodiment, the longitudinal direction of the recess 139 is arranged in parallel or substantially parallel to the longitudinal direction of the developing sleeve 132, and the longitudinal direction of the recess 139 is arranged in parallel to the longitudinal direction of the developing sleeve 132. It is said.

  Further, as shown in FIGS. 5, 6 (a) and 7, a plurality of the recesses 139 are arranged along the longitudinal direction of the developing sleeve 132 and are adjacent to each other in the circumferential direction of the developing sleeve 132. The matching ones are arranged so as to be displaced by about half the length of the recess 139. Further, since the recess 139 is formed on the outer surface of the developing sleeve 132 by the surface treatment apparatus 1 shown in FIG. 8A, the recess 139 is formed on the outer surface of the developing sleeve 132 on the spiral indicated by the one-dot chain line in FIG. They are arranged side by side.

  Further, as shown in FIG. 6B, the recess 139 has a V-shaped cross-sectional shape in the width direction (that is, the circumferential direction of the developing sleeve 132), and as shown in FIG. The cross-sectional shape in the longitudinal direction (that is, the longitudinal direction of the developing sleeve 132) is formed as an arcuate curved surface. Further, since the recess 139 is formed on the outer surface of the developing sleeve 132 by the surface treatment apparatus 1 shown in FIG. 8A, the longitudinal direction thereof is slightly curved in an arcuate shape as shown in FIG. In this embodiment, if the length is longer than the width and the outer edge is formed of a curved line, it is generally called an elliptical shape, whether it is a longitudinal direction, a straight line, or a slight curve.

Furthermore, the length (major axis) in the longitudinal direction of the recess 139 is 1.0 mm or more and 2.3 mm or less, and the width (minor axis) in the width direction is 0.3 mm or more and 0.7 mm or less. The depth is 0.05 mm or more and 0.15 mm or less. Further, about 50 to 250 recesses 139 are provided per 100 mm ² of the outer surface of the developing sleeve 132. That is, the total capacity of the plurality of (many) dents 139 is 0.5 mm ³ or more and 7.0 mm ³ or less per 100 mm ² of the outer surface of the developing sleeve 132. Furthermore, 1.0 or more and 3.0 or less recesses 139 are provided in the circumferential direction of the photosensitive drum 108 that rotates together with the developing sleeve 132. 5, 6 </ b> A, and 7, the horizontal direction in the drawing is the longitudinal direction of the developing sleeve 132.

  In general, the deeper the recess 139, the better the developer conveyance performance, but periodic pitch unevenness is likely to occur as in the case of a conventional developing sleeve having grooves on the outer surface. On the other hand, as the dent 139 is shallower, pitch unevenness is less likely to occur, but the developer transport performance is reduced. Particularly in recent years, the image reproducibility has been improved due to the progress of image forming technology for small particle size toner and magnetic carrier and the image forming technology for proximity development. Therefore, in the developing sleeve 132 described above, the depth of the recesses 139 is set to be shallow, and the distribution density of the recesses 139 is increased to achieve both the developer transport performance and the prevention of pitch unevenness.

  The doctor blade 116 is provided at the end of the developing device 113 near the photosensitive drum 108. The doctor blade 116 is attached to the case 125 described above with a space from the outer surface of the developing sleeve 132. The doctor blade 116 removes 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 is desired. Of thickness.

  In the developing device 113 configured as described above, the developer and the magnetic carrier are sufficiently agitated by the developer supplying unit 114, and the agitated developer is adsorbed to the outer surface of the developing sleeve 132 by a 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 causes the photosensitive drum 108 to attract the developer having a desired thickness by the doctor blade 116. Thus, the developing device 113 carries the developer on the developing roller 115 and transports it to the developing region 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 to develop the electrostatic latent image on the photosensitive drum 108. Used. When the toner supply sensor 114 (described later) detects that the concentration of toner supplied to the photosensitive drum 108 by the developer supply unit 114 has decreased, for example, the developing device 113 moves to the developing device 113 by the operation of the toner supply device 108. Toner is discharged.

  The image forming apparatus 101 having the above-described configuration forms an image on a recording sheet 107 as a recording medium as shown below as an example. First, the image forming apparatus 101 rotates the photosensitive drum 108 and uniformly charges the outer surface of the photosensitive drum 108 to −700 V by the charging roller 109. Laser light is irradiated on the outer surface of the photoconductive drum 108 to expose the photoconductive drum 108, the image portion is attenuated to −150 V, and an electrostatic latent image is formed on the outer surface of the photoconductive drum 108. . When the electrostatic latent image is positioned in the developing area 131, a developing bias voltage of −550 V is applied to the electrostatic latent image, and the developer adsorbed on the outer surface of the developing sleeve 132 of the developing device 113 is photoreceptord. The electrostatic latent image is developed by being attracted to the outer surface of the drum 108, and a toner image is formed on the outer surface of the photosensitive drum 108. The color toner images formed on the photosensitive drums 108 of the process cartridges 106Y, 106M, 106C, and 106K are transferred to the intermediate transfer belt 129 by the intermediate transfer rollers to form color toner images.

  Then, when the recording sheet 107 conveyed by the sheet feeding roller 124 of the sheet feeding unit 103 reaches the position where the intermediate transfer belt 129 of the intermediate transfer unit 104 comes to the position opposite to the sheet transfer roller 126, the image forming apparatus 101. The color toner image formed on the intermediate transfer belt 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.

  On the other hand, the toner remaining on the photosensitive drum 108 without being transferred is collected by the cleaning blade 112. The photosensitive drum 108 from which the residual toner has been removed is subjected to the next image forming process.

  In the image forming apparatus 101 described above, process control is performed in order to suppress image quality fluctuations due to environmental fluctuations and temporal fluctuations. Specifically, first, the developing ability in the developing device 113 is detected. For example, an image of a certain toner pattern is formed on the photosensitive drum 108 or the intermediate transfer belt 129 under a condition where the development bias voltage is constant, and the image density is detected by an optical sensor (not shown) and developed from the density change. Know your ability. Then, the image quality can be kept constant by changing the target value of the toner density so that the developing ability becomes a predetermined target developing ability. For example, when the image density of the toner pattern detected by the optical sensor is lower than the target development density, the CPU as a control unit (not shown) controls the toner supply device 108 to increase the toner density, and the target toner Control to achieve concentration. On the other hand, when the image density of the toner pattern detected by the optical sensor is higher than the target development density, the CPU intentionally develops the toner density so that the toner density is lowered, and the toner density of the developing device 113 is lowered. To do. Here, the toner density is detected by a toner density sensor (not shown).

Next, a manufacturing apparatus for forming the recess 139 on the outer peripheral surface of the developing sleeve 132 will be described.
FIG. 8A is a side view showing a schematic configuration of the surface treatment apparatus 1 that performs cutting on the outer surface of the developing sleeve 132. As shown in FIG. 8A, the surface treatment apparatus 1 includes a base 3, a holding unit 4, a motor 2 as a rotation driving unit, a tool moving unit 5 as a moving unit, a tool 6, and a control unit. And a control device (not shown).

  The base 3 is formed in a flat plate shape and is installed on a factory floor or table. The upper surface of the base 3 is kept parallel to the horizontal direction. The planar shape of the base 3 is formed in a rectangular shape.

  The holding unit 4 includes a fixed holding unit 7 and a slide holding unit 8. The fixed holding unit 7 includes a fixed column 9 erected from one end of the base 3 in the longitudinal direction, and a rotary chuck 10 provided at the upper end of the fixed column 9. The rotary chuck 10 is formed in a thick disc shape, and is supported on the upper end portion of the fixed column 9 so as to be rotatable around the center thereof. The rotation center of the rotary chuck 10 is arranged in parallel with the surface of the base 3, and a cylindrical chuck pin 11 is erected at the center of the rotary chuck 10. Of course, the chuck pin 11 is arranged coaxially with the rotary chuck 10.

  The slide holding unit 8 includes a slider 12, a slide column 13, and a rotary chuck 14 provided at the upper end of the slide column 13. The slider 12 is slidably provided along the surface of the base 3, that is, the axis of the chuck pin 11 of the rotary chuck 10. Further, the slider 12 is configured such that the position of the chuck pin 11 in the axial center direction of the rotary chuck 10 is appropriately fixed.

  The slide column 13 is erected from the slider 12. The rotary chuck 14 is formed in a thick disc shape, and is attached to the output shaft of the motor 2 attached to the upper end portion of the slide column 13. The rotation center of the rotary chuck 14 is arranged coaxially with the chuck pin 11 of the rotary chuck 10 of the fixed holding unit 7. A cylindrical chuck pin 15 is erected at the center of the rotary chuck 14. Of course, the chuck pin 15 is arranged coaxially with the rotary chuck 14.

  In the holding unit 4, the developing sleeve 132 before the recess 139 is formed between the chuck pins 11 and 15 is positioned in a state in which the slide holding unit 8 is separated from the fixed holding unit 7. In a state where the slide holding portion 8 is brought close to the fixed holding portion 7 and the tips of the chuck pins 11 and 15 enter the end portion of the developing sleeve 132 and the developing sleeve 132 is sandwiched between the chuck pins 11 and 15. The slider 12 is fixed. In this way, the holding unit 4 holds the developing sleeve 132 with the developing sleeve 132 sandwiched between the chuck pins 11 and 15.

  The motor 2 is attached to the upper end portion of the slide column 13 of the slide holding portion 8. The motor 2 rotationally drives the rotary chuck 14 around its center. The motor 2 rotates the rotary chuck 14 to rotate the developing sleeve 132 sandwiched between the chuck pins 11 and 15 around its axis.

  The tool moving unit 5 includes a linear guide 16 and a moving actuator (not shown). The linear guide 16 includes a rail 17 and a slider 18. The rail 17 is installed on the base 3. The rail 17 is formed in a straight line, and its longitudinal direction is arranged in parallel with the longitudinal direction of the base 3 and the axis of the developing sleeve 132 sandwiched between the chuck pins 11 and 15, that is, the chuck pins 11 and 15. ing. The slider 18 is supported on the rail 17 so as to be movable along the longitudinal direction of the rail 17.

  The moving actuator is attached to the base 3, and the slider 18 is moved in the longitudinal direction of the base 3 along the axis of the developing sleeve 132 sandwiched between the chuck pins 11 and 15, that is, the chuck pins 11 and 15. Move the slide.

  The tool 6 includes a tool main body 19, a tool rotating motor 20 as a tool rotating unit, and an end mill 21 as a rotating tool. The tool body 19 is formed in a columnar shape standing from the slider 18.

  The tool rotation motor 20 is attached to the upper end of the tool body 19. As shown in FIG. 8B, the tool rotating motor 20 is arranged in a state where its output shaft 22 protrudes from the upper end of the tool body 19 toward the developing sleeve 132 sandwiched between the chuck pins 11 and 15. Has been. The output shaft 22 of the tool rotating motor 20 is in a state in which the shaft core is parallel to the surface of the base 3 and intersects with the shaft core of the developing sleeve 132 sandwiched between the chuck pins 11 and 15 (orthogonal in the illustrated example). Has been placed.

  The end mill 21 is formed in a columnar shape as a whole, and is attached to the tip of the output shaft 22 of the tool rotating motor 20. For this reason, the end mill 21 is arranged in a state where the axis of the end mill 21 is parallel to the surface of the base 3 and intersects the axis of the developing sleeve 132 sandwiched between the chuck pins 11 and 15 (orthogonal in the illustrated example). . The end mill 21 is disposed so as to protrude from the upper end of the tool body 19 toward the developing sleeve 132 sandwiched between the chuck pins 11 and 15.

  As shown in FIG. 8C, the end mill 21 includes a cylindrical main body portion 23 and two cutting blades 24. The main body 23 is attached to the tool main body 19. The cutting blade 24 is provided at a distal end portion of the main body portion 23 near the developing sleeve 132 with an interval in the circumferential direction. As shown in FIG. 8D, the cutting blade 24 is provided so as to protrude from the outer edge of the front end portion of the main body portion 23 toward the outer peripheral direction of the main body portion 23, that is, the end mill 21, and extends in a spiral shape. ing. In the present embodiment, the cross section of the outer edge 25 at the tip of the cutting blade 24 of the end mill 21 is formed to form an acute angle as shown in FIG.

  The tool 6 described above forms a recess 139 on the outer surface of the developing sleeve 132 by the tool rotating motor 20 rotating the end mill 21 around its axis.

  The control device is a computer including a known RAM, ROM, CPU, and the like. The control device is connected to the motor 2 as the rotation drive unit, the movement actuator of the tool moving unit 5, the tool rotation motor 20 of the tool 6, and the like, and controls these to control the entire surface treatment device 1. Control.

  When forming a large number of recesses 139 on the outer surface of the developing sleeve 132, the control device rotates the developing sleeve 132 around its axis by the motor 2 as a rotation drive unit, and the end mill 21 by the tool rotating motor 20. The tool is moved along the axis (longitudinal direction) of the developing sleeve 132 by the moving actuator while rotating around the axis. Then, the control device intermittently cuts the outer surface of the developing sleeve 132 as the end mill 21 rotates to form a large number of recesses 139.

  At this time, the radius of curvature of the arc of the recess 139 in the longitudinal direction of the developing sleeve 132 is determined by the radius of curvature of the outer edge of the cutting blade 24, the depth of the recess 139 is determined by the cutting depth of the cutting blade 24, and the moving speed of the tool 6 A distance between the recesses 139 in the longitudinal direction of the developing sleeve 132 is determined. In addition, the number of the recesses 139 provided in the circumferential direction on the outer surface of the developing sleeve 132 is n, the number of rotations of the motor 2 as the rotation driving unit, that is, the number of rotations of the developing sleeve 132 is N1, and the number of cutting blades 24 of the end mill 21. Is m, and the rotational speed of the end mill 21 is N2, the control device satisfies the following formula (1), the motor 2 as the rotation drive unit, the moving actuator of the tool moving unit 5, and the tool 6 The tool rotation motor 20 is controlled.

  N2 = N1 × [m / [(n / 2) −0.5]] (1)

  The control device can process the outer surface of the developing sleeve 132 by arbitrarily changing the size and density of the recesses 139 by appropriately changing these requirements.

  Further, various input devices such as a keyboard and various display devices such as a display are connected to the control device.

  Next, an example of a process for manufacturing the developing sleeve 132 by cutting the outer surface of the developing sleeve 132 using the surface treatment apparatus 1 having the above configuration will be described.

  First, the product number of the developing sleeve 132 is input from the input device to the control device. Then, after the control device positions the end mill 21 as the rotary tool of the tool 6 at the processing start position, that is, at one end of the developing sleeve 132, the developing sleeve 132 before the recess 139 is formed is held by the holding unit 4. To do. At this time, the developing sleeve 132 and the chuck pins 11 and 15 are coaxial.

  Then, when a work start command is input from the input device, based on Equation 1 described above, the control device causes the motor 2 as the rotation drive unit, the moving actuator of the tool moving unit 5, and the tool rotating motor of the tool 6. 20 is driven. Then, the cutting blade 24 of the end mill 21 that rotates around the shaft core intermittently cuts the outer surface of the developing sleeve 132, thereby forming the recess 139. That is, the recess 139 is formed by cutting the outer surface of the developing sleeve 132 by the rotary tool 6 rotated around the axis.

  Further, since the motor 2 as the rotation driving unit, the moving actuator of the tool moving unit 5 and the tool rotating motor 20 of the tool 6 are simultaneously driven, the development is performed by the rotating tool 6 in which the recess 139 is rotated around the axis. When the outer surface of the sleeve 132 is formed by cutting, the developing sleeve 132 disposed so as to intersect with the end mill 21 (orthogonal in the illustrated example) is rotated about its axis, The developing sleeve 132 is relatively moved in the longitudinal direction of the developing sleeve 132 to form a recess 139.

  When the end mill 21 is positioned at the processing end position of the developing sleeve 132, that is, at the other end of the developing sleeve 132, and the above-described cutting of the outer surface of the developing sleeve 132 is completed, the motor 2 as the rotational drive unit and the tool The moving actuator of the moving unit 5 and the tool rotating motor 20 of the tool 6 are stopped. Then, the slide holding portion 8 is separated from the fixed holding portion 7, and the developing sleeve 132 having a large number of dents 139 formed on the outer surface is taken out between the chuck pins 11, 15 of the holding portions 7, 8, and a new developing sleeve 132 is taken out. Is held by the holding unit 4. In this way, the outer surface of the developing sleeve 132 is cut to form a large number of recesses 139 on the outer surface, and the developing sleeve 132 (shown in FIG. 4) described above is obtained.

  The developing sleeve 132 manufactured in the above process does not have a convex portion that is formed by a conventional sandblasting process on the outer surface, and the concave portion 139 is formed into a larger concave portion. Therefore, it is difficult to wear, and thus it is possible to suppress a decrease in the transport amount of the developer due to aging.

  Further, since the developing sleeve 132 is regularly arranged so that the recesses 139 formed on the outer surface do not overlap with each other, the developer accumulates in the recesses 139. Therefore, the location where the developer accumulates is regularly arranged on the outer surface. Therefore, it is possible to prevent image unevenness from occurring. Furthermore, it is possible to cope with further increase in pumping amount in order to maintain high image quality in future high-speed machines.

  Furthermore, since the recesses 139 are regularly arranged, it is easy to set processing conditions capable of extending the service life while ensuring an optimal developer pumping amount, and reliably under the set conditions. The recess 139 can be formed, and the effect of excellent workability is achieved.

Further, a plurality of recesses 139 that are long in the longitudinal direction are regularly arranged on the outer surface of the developing sleeve 132, and the total volume of the recesses 139 is set to 0.5 mm ³ or more per 100 mm ² of the outer surface area of the developing sleeve 132. Therefore, a sufficient developer conveying force can be obtained.

  Since the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 are displaced in the longitudinal direction of the developing sleeve 132, many portions and recesses 139 are formed on the outer surface of the developing sleeve 132 where the recess 139 is not formed. It is possible to prevent the occurrence of a spot or the like. Accordingly, unevenness occurs in the developer adsorbed on the outer surface of the developing sleeve 132, that is, the developer can be adsorbed uniformly on the outer surface of the developing sleeve 132. Therefore, it is possible to prevent image unevenness.

  In the example of the manufacturing configuration described above, the circumferential section of the developing sleeve 132 of the recess 139 is formed in a V shape. However, as shown in FIGS. 9A to 9C, the developing sleeve 132 of the recess 139 is formed. The circumferential cross section may be formed in an arc shape. In the illustrated example, both the circumferential direction and the longitudinal direction of the developing sleeve 132 of the recess 139 are formed in an arc shape. In this case, as shown in FIG. 11, the outer edge 25 of the cutting blade 24 of the end mill 21 is formed in an arc shape, so that the circumferential section of the developing sleeve 132 of the recess 139 is formed in an arc shape. In addition, the angle θ (shown in FIG. 10) formed by the inner surface of the recess 139 and the outer surface of the developing sleeve 132 in the circumferential cross section of the developing sleeve 132 is generated due to the influence of the developing magnetic pole described above. In order to avoid a difference in development density, it is preferably 60 degrees or less. 9 to 11, the same parts as those in FIGS. 6 to 8 described above are denoted by the same reference numerals and description thereof is omitted.

  According to the cases shown in FIGS. 9 to 11, since both the longitudinal and circumferential sections of the developing sleeve 132 of the recess 139 are formed in an arc shape, the amount of developer that can be accommodated in the recess 139. A sufficient amount of developer can be conveyed.

  Further, in the examples of FIGS. 6 to 8 described above, the cross section of the recess 139 in the circumferential direction of the developing sleeve 132 is formed in a V shape, but the shape of the outer edge 25 of the cutting blade 24 can be changed as appropriate. 12 and FIG. 13, the cross-sectional shape of the recess 139 in the circumferential direction of the developing sleeve 132 may be appropriately changed. FIG. 12 shows a case where the bottom of the V-shaped recess 139 is formed flat, and FIG. 13 shows a case where the bottom of the V-shaped recess 139 is formed in an arc shape. 12 and 13, the same parts as those in FIGS. 6 to 8 described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the example of FIGS. 6 to 8 described above, the motors 2 and 20 and the actuator are operated simultaneously and continuously to dispose the recesses 139 on the outer surface of the developing sleeve 132 in a spiral manner. Although slightly curved in an arcuate shape, as shown in FIGS. 14 and 15, the motors 2, 20 and the actuator are operated appropriately and appropriately so that the dent 139 extends along the longitudinal direction of the developing sleeve 132. In addition to being formed in a straight line, the plurality of recesses 139 may be arranged on a straight line along the circumferential direction of the developing sleeve 132.

  Further, in the examples of FIGS. 6 to 8 described above, the recess 139 is formed in an elliptical shape, but the end mill 21 (shown in FIG. 16B) having an outer diameter D1 smaller than that of the above-described embodiment is used. Then, the recess 139 may be formed in a circular shape in plan view as shown in FIG.

  In the image forming apparatus 101 described above, the process cartridges 106Y, 106M, 106C, and 106K include a cartridge case 111, a charging roller 109, a photosensitive drum 108, a cleaning blade 112, and a developing device 113. However, the process cartridges 106Y, 106M, 106C, and 106K only need to include at least the developing device 113, and do not necessarily include the cartridge case 111, the charging roller 109, the photosensitive drum 108, and the cleaning blade 112. In the above-described embodiment, the image forming apparatus 101 includes the process cartridges 106Y, 106M, 106C, and 106K that are detachable from the apparatus main body 102. However, the image forming apparatus 101 according to the present embodiment only needs to include the developing device 113 and does not necessarily include the process cartridges 106Y, 106M, 106C, and 106K.

Next, the developing device of this embodiment will be described in detail.
FIG. 17 is a schematic configuration diagram of the developing device, and shows the strength of the magnetic flux density in the normal direction of the magnet roller. In FIG. 17, the magnet roller 133 includes a plurality of fixed magnetic poles as magnetic field generating means, P1 pole (development pole), P2 pole (developer transport pole), P3 pole (developer transport pole), and P4 pole (agent separation). An upstream pole) and a P5 pole (agent-separated downstream pole = developer pumping pole) are provided. Among the plurality of fixed magnetic poles, the P2 pole and the P3 pole have transporting magnetic poles for generating a magnetic force for transporting the two-component developer after passing through the developing area to a position where the two-component developer is separated from the surface of the developing sleeve. It has a function as a magnetic field generating member.

  The developing sleeve 132 rotates in the direction of the arrow in the figure, and the developer in the second space 121 is pumped up to the surface of the developing sleeve 132 by the magnetic force of the magnet roller 133 and adheres to the surface of the developing sleeve. Thereafter, the amount of the developer on the developing sleeve is made uniform by the doctor blade 116, and subsequently, the image carrier 108 and the developer carrier are conveyed to a developing area facing each other with a space therebetween. The developer develops the electrostatic latent image formed on the image carrier 108 to form a toner image. Thereafter, the developer passes through the opening 125a of the case 125, and is conveyed to the agent separation portion while being influenced by the magnetic force of the P2 pole (developer conveyance pole) and the P3 pole (developer conveyance pole), and the P4 pole ( The developer is separated from the developing sleeve by the upstream electrode), collected in the second space 121, and stirred and conveyed by the stirring screw 118.

  Here, the inner wall of the case 125 and the outer periphery of the developing sleeve 132 are positioned downstream of the opening 125 a of the case 125 in the rotation direction of the developing sleeve 132 and before the position where the two-component developer is separated from the developing sleeve 132. A predetermined gap is provided between the surfaces. The distance between the inner wall of the case 125 and the outer peripheral surface of the developing sleeve 132 for forming this gap is called a casing gap. Further, the magnetic force is exerted on at least one of the P2 pole and the P3 pole in the gap.

  FIG. 18 is an enlarged view of the vicinity of the P2 pole and the P3 pole, for explaining the casing gap. In FIG. 18, for example, the casing gap GP2 between the outer peripheral surface of the developing sleeve and the case inner wall at the position where the P2 pole faces is 1.8 mm, and the casing gap GP3 between the outer peripheral surface of the developing sleeve and the case inner wall at the position where the P3 pole faces. It is set to about 1.0 mm. By setting the casing gap in this manner, when the developer that has risen on the developing sleeve passes through the gap between the inner wall of the case 125 and the outer peripheral surface of the developing sleeve 132, air is developed together with the developer. It can be conveyed in the sleeve rotation direction to create a suction airflow and prevent toner scattering from the case opening.

  However, when the developing sleeve 132 having a plurality of recesses 139 provided at regular intervals on the outer peripheral surface is used, toner may be scattered outside the developing device. The present inventors diligently conducted experiments and studies on this cause, and as a result, it was found that the cause was the setting of the interval between the recesses 139 in the circumferential direction. That is, in the developing sleeve 132, the developer is carried in the recess 139, and thus the developer spikes in the recess 139. For this reason, if the interval between the circumferential recesses 139 is too wide, the air leaks from the gaps between the developers that stand up in the recesses 139, and it is difficult for the suction airflow to occur. As a result, it has been found that toner scattering occurs outside the developing device. Further, the developer rises along the magnetic field lines generated at the P2 pole and P3 pole of the magnet roller 133, but on the outer peripheral surface of the developing sleeve corresponding to the full width at half maximum of the magnetic flux density in the direction orthogonal to the longitudinal direction of the P2 pole and P3 pole. In, it was found that the heading was surely performed. Therefore, the circumferential arrangement pitch of the recesses 139 on the outer peripheral surface of the developing sleeve is determined from the peripheral length of the outer peripheral surface of the developing sleeve (hereinafter referred to as “casing gap width”) corresponding to the magnetic flux density half width of the P2 pole and P3 pole. Was also set small.

  The arrangement pitch Pc in the circumferential direction of the recesses 139 is, for example, for the P3 pole. In FIG. 18, the half-width of the magnetic flux density in the direction orthogonal to the longitudinal direction of the P3 pole is about 40 degrees around the magnet roller axis. When the diameter of the developing sleeve 132 is 18 mm, the casing gap width WGP3 is about 6.28 to 6.40 mm. The circumferential arrangement pitch of the recesses 139 is set to be smaller than the casing gap width WGP3 so that at least one pair of recesses 139 adjacent to each other in the circumferential direction exists in the casing gap width WGP3. In the present embodiment, in consideration of the safety factor, the arrangement pitch Pc in the circumferential direction of the recesses 139 is set to 1 mm or less so that a sufficient number of recesses 139 are included in the casing gap width. As a result, a sufficient suction airflow can be generated, and toner scattering from the case opening can be suppressed.

  The pitch Pc in the circumferential direction of the recesses 139 is set based on the half-width of the magnetic flux density in the direction perpendicular to the longitudinal direction of the P3 pole, but the half-width of the magnetic flux density in the direction perpendicular to the longitudinal direction of the P2 pole. You may set based on. Further, as described above, the interval between the recesses 139 formed on the outer peripheral surface of the developing sleeve can be adjusted by the cutting tool bite, the rotational speed, the feed speed, and the sleeve rotational speed.

  FIG. 19 is an explanatory diagram illustrating a comparative example for explaining toner scattering. In FIG. 19, the arrangement pitch Pc of the circumferential recesses 139 is set larger than the casing gap width WGP3. Then, a space formed by the rising of the developer in the recess 139 is large, and air leaks from the gap between the ears, and the air cannot be conveyed into the developing device. For this reason, an air flow into the developing device cannot be generated, and if toner that is insufficiently charged and insufficiently adsorbed by the carrier is released from the carrier, the toner may be scattered from the opening 125a to the outside of the developing device. is there.

  FIG. 20 is an example of a perspective view in which a part of the developing sleeve 132 is enlarged. In FIG. 20, the elliptical recesses 139 provided on the outer peripheral surface of the developing sleeve form a plurality of rows in the circumferential direction, and the positions of the recesses 139 are shifted in the circumferential direction between adjacent rows. Further, in the illustrated example, the longitudinal direction of the recess 139 coincides with the rotation axis direction of the developing sleeve 132.

  Further, as shown in the figure, the arrangement pitch Pa of the recesses 139 between adjacent rows in the developing sleeve axial direction is preferably equal to or less than the length L of the recesses 139 in the developing sleeve rotation axis direction. That is, the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 are provided so as to be shifted from each other in the rotational axis direction of the developing sleeve 132, and the deviation amount of the recess 139 in the rotational axis direction of the developing sleeve 132 is the recess 139. Or less than the length L in the direction of the rotation axis. As a result, the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 are provided so that a gap in the rotation axis direction does not occur between the end portions. Therefore, when the developing sleeve 132 is rotated, the developer spiked in the recess 139 hardly leaks air from both ends of the spike in the rotation axis direction, and a sufficient suction airflow can be generated. .

  In this embodiment, when the developing device 113 is configured to be detachable from the apparatus main body 102, the developing device 113 can be attached and detached in the gap between the inner wall of the case 125 and the outer peripheral surface of the developing sleeve 132. An air flow from the front side to the back side may be generated.

  FIG. 21 is a perspective view of the developing device 113 as viewed from the longitudinal direction, and shows an example of a change in the number density of the recesses 139 provided on the outer peripheral surface of the developing sleeve 132. An arrow in FIG. 21 indicates an insertion direction when the developing device 113 is attached to the apparatus main body 102. Moreover, the part shown with the dashed-two dotted line in the figure has shown the enlarged view to which the outer peripheral surface of the developing sleeve 132 was expanded. The developing device 113 is attached to and detached from the apparatus main body 102 integrally with the process cartridge 106 in a state of being incorporated in a process cartridge 106 (not shown). However, only the developing device 113 may be detachable from the apparatus main body 102. .

  As shown in FIG. 21, the density per unit area of the recesses 139 provided on the outer peripheral surface of the developing sleeve is small on the front side in the attaching / detaching direction of the developing device 113 and gradually increases toward the back side. That is, the arrangement pitch of the recesses 139 in the circumferential direction of the developing sleeve 132 is smaller on the back side than on the front side in the attaching / detaching direction of the developing device 113. In this developing sleeve 132, the density of the spikes of the developer carried in the recesses 139 is larger on the back side than on the front side in the attaching / detaching direction of the developing device 113, and a stronger suction airflow is generated on the back side when rotated. To do. Then, a suction air flow is generated from the front side in the attaching / detaching direction of the developing device 113 toward the back side. As a result, even if the insufficiently charged toner is released in the vicinity of the opening on the front side of the developing device 113 in the attaching / detaching direction, the toner is sucked into the suction airflow and carried to the inside of the developing device 113 in the attaching / detaching direction, to the outside of the developing device. Can be prevented. Therefore, when a service person or a user pulls out the developing device 113 with the front side in the attaching / detaching direction so that the developing device 113 can be replaced or confirmed, the toner scatters from the front side in the attaching / detaching direction of the developing device 113. It is possible to prevent the hand holding the developing device 113 from getting dirty.

  Further, in this embodiment, in order to generate an air flow from the front side in the attaching / detaching direction of the developing device 113 to the back side in the gap between the inner wall of the case 125 and the outer peripheral surface of the developing sleeve 132, The elliptical dent may have an oblique angle with respect to the rotational axis direction of the developing sleeve 132 in the longitudinal direction of the dent.

  22A and 22B are explanatory views of the developing sleeve 132 in which the longitudinal direction of the recess 139 is oblique with respect to the rotation axis direction of the developing sleeve 132, wherein FIG. 22A is a perspective view of the developing sleeve 132, and FIG. It is the A section enlarged view of an outer peripheral surface. As shown in FIGS. 22A and 22B, the longitudinal direction of the elliptical recess 139 has an angle with respect to the rotation axis direction of the developing sleeve 132. When the developing sleeve 132 rotates in the direction of arrow B in the figure, an air flow is generated in the direction of arrow C in FIG. Further, at the agent separation position where the developer separates from the developing sleeve 132, the developer separates toward the back side of the developing device in the attaching / detaching direction (the direction of arrow C at the agent separating portion). Accordingly, it is possible to generate a suction air flow toward the rear side in the developing device attaching / detaching direction with the rotation of the developing sleeve 132. Therefore, even if the insufficiently charged toner is released in the vicinity of the opening on the near side of the developing device 113 in the attaching / detaching direction, the toner is sucked into the suction airflow and carried to the inside of the developing device 113 in the attaching / detaching direction, and to the outside of the developing device. Can be prevented. In particular, toner scattering on the near side of the developing device 113 in the attaching / detaching direction can be suppressed.

  Further, in the developing sleeve 132, as shown in FIG. 21, the density per unit area of the recesses 139 provided on the outer circumferential surface of the developing sleeve is gradually reduced toward the back side while the developing device 113 has a small front side in the attaching / detaching direction. It may be made larger. Thereby, with the rotation of the developing sleeve 132, a stronger suction air flow toward the rear side in the attaching / detaching direction of the developing device can be generated, and toner scattering on the front side in the attaching / detaching direction can be more reliably suppressed.

As described above, according to the present embodiment, the magnet roller 133 as the magnetic field generating means is disposed inside the developing sleeve 132 as a sleeve-like hollow body made of a non-magnetic member, and can be driven by the magnetic force of the magnet roller 133. A developing roller 115 as a developer carrying member that carries and conveys a two-component developer containing a magnetic carrier and toner on the outer peripheral surface of 132, and development that contains the two-component developer carried on the developing roller 115 A storage tank 117 as an agent storage section, a doctor blade 116 as a developer regulating member that regulates the layer thickness of the two-component developer carried on the developing roller 115, a developing roller 115, a storage tank 117, and a doctor blade And a case 125 as a housing for housing 116. The two-component developer carried on the developing roller 115 by the magnetic force of the magnet roller 113 from the inside of the storage tank 117 is regulated by the doctor blade 116, and is then applied to the outer peripheral surface of the developing sleeve 132 from the opening provided in the case 125. A part of the toner is exposed to pass through a developing area facing the photosensitive member 108 as a latent image carrier, and returned to the storage tank 117 again. The magnet roller 113 has a P2 pole and a P3 pole as magnetic field generating members having a magnetic pole for conveying to generate a magnetic force for conveying the two-component developer after passing through the developing area to a position where the two-component developer is separated from the developing roller 115. The inner wall of the case 125 and the outer peripheral surface of the developing sleeve 132 between the opening of the case 125 and the downstream side in the rotation direction of the developing sleeve 132 until the position where the two-component developer is released from the developing roller 115. And a predetermined gap. The developing sleeve 132 is provided with a plurality of recesses 139 as recesses distributed on the outer peripheral surface of the developing sleeve 132 at intervals, and the arrangement pitch Pc of the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 is It is set shorter than the length WGP3 of the portion corresponding to the half-width of magnetic flux density in the direction orthogonal to the longitudinal direction of the P3 pole on the outer peripheral surface of the developing sleeve 132. By setting the circumferential arrangement pitch Pc of the recesses 139 in this way, at least two recesses 139 exist in a portion corresponding to the half-value width of the magnetic flux density on the outer peripheral surface of the developing sleeve 132, and these recesses 139. The developer carried on the head rises. When the developer carried in these recesses 139 rises, the casing gap between the outer peripheral surface of the developing sleeve 132 and the inner wall of the case 125 is partitioned. The existing air is conveyed to the storage tank 117 inside the developing device. When the air is conveyed to the storage tank 117, a negative pressure is generated in the casing gap, and external air flows from the opening of the developing device to generate a suction airflow. Therefore, even if the insufficiently charged toner is released in the vicinity of the opening of the developing device, the toner is sucked into the suction airflow and carried into the developing device and is not scattered outside the developing device.
In the present embodiment, the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 are provided so as to be shifted from each other in the rotation axis direction of the developing sleeve 132. The amount is equal to or less than the length of the recess 139 in the rotation axis direction. Accordingly, the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 are provided so as not to generate a gap in the rotation axis direction between the end portions, and the developer in the rotation axis direction when the developing sleeve 132 rotates. Air from both ends of the head of the nose becomes difficult to leak, and a sufficient suction airflow can be generated.
In the present exemplary embodiment, the image forming apparatus main body is configured to be detachable in the direction of the rotation axis of the developing sleeve 132, and the developing device itself is detachable from the front side to the back side with respect to the rotation axis direction of the developing sleeve 132. It was configured to generate an airflow toward Even if the insufficiently charged toner is released in the vicinity of the opening on the near side of the developing device in the attaching / detaching direction, the toner is sucked into the air flow and carried to the inside in the attaching / detaching direction, and scattering to the outside of the developing device can be prevented. Therefore, when a serviceman or user pulls out the developing device with the front side in the attaching / detaching direction so that the developing device can be replaced or confirmed, the toner scatters from the front side in the attaching / detaching direction of the developing device or the developing device is removed. It can prevent your hand from getting dirty.
Further, in the present embodiment, the arrangement pitch of the recesses 139 in the circumferential direction of the developing sleeve 132 is smaller on the back side than on the near side in the attaching / detaching direction of the developing device itself. In this developing sleeve 132, the density of the spikes of the developer carried in the recesses 139 is larger on the back side than on the front side of the developing device in the attaching / detaching direction, and a stronger suction airflow is generated on the back side when rotated. . As a result, a suction air flow is generated from the front side in the mounting / demounting direction of the developing device toward the back side.
In this embodiment, the recess 139 provided on the outer peripheral surface of the developing sleeve 132 has an oval or elliptical shape, and the longitudinal direction of the recess 139 is relative to the rotation axis direction of the developing sleeve 132. And have an angle. The angle was set so as to generate an air flow from the front side to the back side of the developing device itself with respect to the rotation axis direction of the developing sleeve 132. When the developing sleeve 132 rotates, an air flow directed toward the rear side in the attaching / detaching direction of the developing device is generated by the developer that has risen in the recess 139. Further, at the agent separation position where the developer separates from the developing sleeve, the developer separates toward the back side in the attaching / detaching direction of the developing device. Accordingly, it is possible to generate a suction air flow toward the rear side in the developing device attaching / detaching direction with the rotation of the developing sleeve 132.
In the exemplary embodiment, the toner includes a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent are dispersed in an organic solvent. Among them, a toner obtained by performing at least one of crosslinking and extension reaction is preferable.

101 Image forming apparatus 106Y, 106M, 106C, 106K Process cartridge 108 Photosensitive drum (photosensitive member)
109 Charging roller (charging device)
113 Developing Device 115 Developing Roller 132 Developing Sleeve 133 Magnet Roller 139 Recess

JP 2009-80447 A

Claims (8)

A magnetic field generating means is disposed inside a sleeve-like hollow body made of a non-magnetic member that can be driven to rotate, and a two-component developer containing a magnetic carrier and toner on the outer peripheral surface of the hollow body by the magnetic force of the magnetic field generating means A developer carrying member carried and conveyed;
A developer accommodating portion for accommodating a two-component developer carried on the developer carrying member;
A developer regulating member for regulating the layer thickness of the two-component developer carried on the developer carrying body;
A housing for housing the developer carrying member, the developer accommodating portion, and the developer regulating member;
After the two-component developer carried on the developer carrying member by the magnetic force of the magnetic field generating means from inside the developer containing portion is regulated by the developer regulating member, the hollow is opened from the opening provided in the housing. A developing device that exposes a part of the outer peripheral surface of the body, passes through a developing region facing the latent image carrier, and returns the developer image into the developer container.
The magnetic field generating means has a magnetic field generating member having a magnetic pole for conveyance for generating a magnetic force for conveying the two-component developer that has passed through the development region to a position where the two-component developer is separated from the developer carrier.
The inner wall of the casing and the hollow body are positioned downstream of the opening of the casing in the rotational direction of the hollow body and before the position where the two-component developer is separated from the developer carrier. It is configured to have a predetermined gap between the outer peripheral surface,
The hollow body is provided on the outer peripheral surface so as to distribute a plurality of recesses at intervals from each other,
The arrangement pitch of the recesses adjacent to each other in the circumferential direction of the hollow body is shorter than the length of the portion corresponding to the half-width of magnetic flux density in the direction orthogonal to the longitudinal direction of the magnetic field generating member on the outer circumferential surface of the hollow body. A developing device characterized by being set. The developing device according to claim 1.
The recesses adjacent to each other in the circumferential direction of the hollow body are provided so as to be shifted from each other in the direction of the rotation axis of the hollow body,
The developing device characterized in that the amount of displacement of the recess in the direction of the rotation axis of the hollow body is equal to or less than the length of the recess in the direction of the rotation axis. The developing device according to claim 1 or 2,
The image forming apparatus main body is configured to be detachable in the direction of the rotation axis of the hollow body,
A developing device configured to generate an air flow from the front side to the back side in the attaching / detaching direction of the developing device with respect to the rotation axis direction of the hollow body. The developing device according to claim 3.
The developing device characterized in that the arrangement pitch of the recesses in the circumferential direction of the hollow body is smaller on the back side than on the front side in the attaching / detaching direction of the developing device itself. The developing device according to claim 3 or 4,
The recess provided on the outer peripheral surface of the hollow body has an oval or elliptical shape, and the longitudinal direction of the recess has an oblique angle with respect to the rotation axis direction of the hollow body. A developing device characterized in that the angle is set so as to generate an air flow from the front side to the back side in the attaching / detaching direction of the developing device with respect to the rotation axis direction of the body. Development in which a latent image carrier and a two-component developer composed of a magnetic carrier and toner are transported to a development area facing the latent image carrier and the toner is attached to the latent image on the latent image carrier for development. An image forming apparatus that integrally supports the apparatus and forms an image on the recording material by finally transferring the toner image obtained by development by the developing device from the latent image carrier onto the recording material. On the other hand, in the removable process cartridge,
A process cartridge using the developing device according to claim 1 as the developing device. Development in which a latent image carrier and a two-component developer composed of a magnetic carrier and toner are transported to a development area facing the latent image carrier and the toner is attached to the latent image on the latent image carrier for development. An image forming apparatus that integrally supports the apparatus and forms an image on the recording material by finally transferring the toner image obtained by development by the developing device from the latent image carrier onto the recording material. In an image forming apparatus provided with a process cartridge that is detachable from the image forming apparatus,
An image forming apparatus using the process cartridge according to claim 6 as the process cartridge. The image forming apparatus according to claim 7.
In the toner, at least one of a crosslinking and extension reaction in an aqueous medium is carried out in a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant and a release agent are dispersed in an organic solvent. An image forming apparatus characterized in that the toner is obtained by performing the above.

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