JP2011164366A - Developing device and image forming apparatus provided with the same and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device which prevents an increase in size of the device and prevents image density from being uneven due to improper flow of two-component developer on a surface of a developer carrier, when the developer carrier in which a carrying force of the two-component developer is generated in a rotational axis direction by a plurality of oval or ellipsoidal concave portions obliquely formed at an outer periphery is used, and to provide an image forming apparatus provided with the developing device and a process cartridge. <P>SOLUTION: At both ends in a longitudinal direction of a magnet roller 133, magnet roller shafts 134 are provided as support shafts formed of a magnetic body, and the magnet roller shafts 134 have different lengths in the longitudinal direction. The length L2 of one magnet roller shaft 134b at a downstream side of a developer moving direction in a developing roller rotational axis direction caused by movement of the outer periphery having a concave 139 of a developing sleeve 132 at a position of a developer releasing portion where the developer is released from a developing roller 115 is shorter than the length L1 of the other magnet roller shaft 134a. <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.

  FIG. 19 is a schematic configuration diagram showing an example of a conventional general developing device. This developing device conveys a two-component developer to a developing area where the developer carrying member and the image carrying member face each other, and develops the electrostatic latent image formed on the surface of the image carrying member to form a toner image. A developer carrier is provided. The developer carrying member includes a developing sleeve 241 formed in a cylindrical shape, and a magnet roller 247 that is accommodated in the developing sleeve 241 and forms a magnetic field so as to cause developer spikes on the surface of the developing sleeve 241. It is equipped with. In this developer carrier, when the developer spikes, the magnetic carrier constituting the developer spikes on the developing sleeve 241 along the magnetic force lines generated by the magnet roller 247 and the spiked magnetic The toner constituting the developer adheres to the carrier.

  Further, the developing device includes a developer storage tank that stores the developer, a screw-shaped stirring and conveying member that stirs the developer in the developer storage tank, and a developer pump pumped up to the developer carrier. And a developer regulating member that makes the amount uniform. In the developing device shown in FIG. 19, a pair of a developer storage tank and a stirring member are provided, and the developer moves in the developer storage tank in the axial direction of the stirring member. The toner replenished from one end of one developer storage tank 249B on the side away from the developer carrying member is moved in the axial direction of the stirring member 242 to the other end of the developer storage tank 249B by one stirring member 242. The developer is agitated while being conveyed. Then, the developer moves from the other end of the one developer storage tank 249B to the other developer storage tank 249A near the developer carrier. The developer transferred to the other developer storage tank 249A near the developer carrying member is pumped up to the surface of the developing sleeve 241 by the magnetic force of the magnet roller 247 and adheres to the surface of the developing sleeve. Thereafter, the amount of the developer on the developer carrying member is made uniform by the developer regulating member 146, and subsequently, the image carrying member 12 and the developer carrying member are conveyed to a developing region facing each other with a space therebetween. The The developer develops the electrostatic latent image formed on the image carrier 12 to form a toner image.

  The magnet roller 247 includes a plurality of fixed magnetic poles such as S1 (developing pole), N1 (developer transport pole), S2 (agent separating upstream pole), S3 (pumping pole = agent separating downstream pole), N2 (developer). Each of the transport poles is provided. Since the developing sleeve 241 rotates in the direction of the arrow, the developer moves on the surface of the developing sleeve 241 in the order of fixed magnetic pole S 3 → N 2 → S 1 → N 1 → S 2 → agent separation. In the magnet roller 247, the fixed magnetic pole N1 (developer transport pole) and the fixed magnetic pole N2 (developer transport pole) have the same N polarity, and the S-polarity pole p between the fixed magnetic pole S2 and the fixed magnetic pole S3. Is provided, the developed developer having a low toner concentration is dropped into the developer storage tank 249A by the repulsive force of the magnetic pole p in addition to the repulsive force of the fixed magnetic pole S2 and the fixed magnetic pole S3. Such a magnetic pole p (P) is called an “agent separating pole”, and the developed developer is dropped into the developer storage tank 249A by the repulsive force of the magnetic pole p (P). In this way, the developed developer having a reduced toner concentration, which is separated from the surface of the developing sleeve 241 and dropped into the developer storage tank 249A, is removed from the developer stirring tank 249B in the developer stirring tank 249A. It is stirred together with a new developer having a high toner concentration. After that, the developer whose toner density has been increased by the fixed magnetic pole S3 (developer pumping pole) is pumped up and attracted onto the developing sleeve 241 and transferred to the fixed magnetic pole N1 (developer transport pole). The developer having a high toner density transferred to the fixed magnetic pole N1 is transferred to the fixed magnetic pole S1 (development pole) by a constant amount by the developer regulating member.

Further, in Patent Document 1, as shown in FIG. 20, the two electrodes, the pumping electrode (S3 electrode) and the developer conveying electrode (N2 electrode) described in FIG. In the example, the developing device is disclosed for the purpose of lowering the stress of the developer and ensuring the agent releasability of the developer carrier itself.
Further, Patent Document 2 focuses on the magnetic force at the agent separating portion for separating the developer after passing through the developing region from the developer carrying member in order to further improve the agent separating property by the magnetic pole arrangement. By disposing a magnet outside the outer peripheral surface of the developer carrier on the upstream side of the developer carrying direction by the developer carrier relative to the developer regulating member, and defining the position of the magnet and the magnitude of the magnetic force A developing device that prevents re-adsorption of the developer onto the developer carrying member is disclosed.

  However, the separation of the developer from the developer carrying member has the following problems at both ends of the developer carrying member in the rotation axis direction. FIG. 21 and FIG. 22 are diagrams for explaining this problem, and are explanatory diagrams showing the behavior of the developer on the surface of the developing sleeve 241 in the developing device shown in FIG. FIG. 21A is an explanatory diagram showing the distribution of the normal direction magnetic flux density (absolute value) on the surface of the developing sleeve, and FIG. 21B is the behavior of the developer at the central portion (image forming area) of the developing sleeve. FIG. 3C is an explanatory view of the behavior of the developer at the end of the developing sleeve (outside the image forming region) as seen from the cross-sectional direction. FIG. 22 is an explanatory view of the behavior of the developer at the end of the developing sleeve (outside the image forming area) as viewed from the side.

In FIG. 22, within the width of the developing effective area on the surface of the developing sleeve 241 facing the image forming area where the latent image can be formed on the image carrier 12 (hereinafter referred to as “developing effective width”), the agent is separated. The peeling force due to the agent separation upstream pole (N2) at the portion effectively acts on the developer, and the developer detaches from the surface of the developing sleeve 241 and falls into the developer storage tank 249A as shown in FIG. To do. The developer dropped in the developer storage tank 249A is agitated and mixed with the developer in the developer storage tank, and is again pumped up to the developing sleeve 241 by the pumping pole (N3). On the other hand, in the region on the developing sleeve corresponding to the magnet roller 247, the portion outside the developing effective width in the axial direction of the developing sleeve (hereinafter referred to as “magnet roller end region”) is developed as shown in FIG. The developer adheres to the surface of the developing sleeve, and there remains developer that does not leave the surface of the developing sleeve 241. That is, in the magnet roller end region, the developer separated at the agent separation upstream pole (N2) passes through the outside of the magnet roller (the portion having no magnetic force) toward the agent separation downstream pole (N3). Then, as shown in FIG. 21 (c), the developer is hardly separated from the surface of the developing sleeve, and is pumped up to the agent separation downstream pole (N3). That is, the developer is accompanied in the magnet roller end region.
The magnetic pole provided on the magnet roller 247 is similar to the agent separation portion where the agent separation upstream pole (N2) and the agent separation downstream pole (N3) are adjacent to each other in the agent separation portion. In other parts, the N and S poles are adjacent to each other. In the portions other than the agent separation portion, adjacent different polarities carry the developer, so that the developer is attracted from S to N and from N to S without flowing to the end portion. On the other hand, since this portion has the same polarity in the agent separation portion, it repels each other, and in particular, in the magnet roller end region, the magnetic component toward the outer side in the rotation axis direction becomes stronger, so FIGS. As shown in FIG. 5, the developer behaves and the developer is accompanied. If the magnet roller end region where such developer rotation occurs is also within the effective development width, the developer is accommodated by the developer rotation at both ends of the image in the axial direction of the developing sleeve. Since the toner from the tank is not replenished, the image density is lowered and image density unevenness occurs.

For this reason, conventionally, the developer is allowed to rotate in the end region of the magnet roller, and the rotation axis direction of the developer carrier is lengthened so that it is outside the effective development width (image guarantee region) used for development on the surface of the developing sleeve. The mainstream is a structure that generates a follow-up. In this configuration, the size of the apparatus increases as the developer carrying member becomes longer.
As another countermeasure, it is conceivable that a magnetic axis is not directed from the magnetic pole of the magnet roller to the fixed shaft by using a non-magnetic member as the fixed shaft for fixing the magnet roller. Thereby, as the nonmagnetic member of the fixed shaft, stainless steel or aluminum can be considered. However, when stainless steel is used, the cost increases, and when aluminum is used, the strength becomes insufficient.

In Patent Document 3, the developer density on the developing sleeve is maintained similar to that of a developing sleeve having irregular irregularities such as sandblasting on the surface, and the developer is transported in the same manner as a developing sleeve having grooves on the surface. A developing sleeve that retains force is disclosed. FIG. 23 is an enlarged view of the surface of the developing sleeve as viewed from the side and is approximately 2 to 3 cm ² . In the drawing, an elliptical concave portion is provided on the surface of the developing sleeve so as to have an angle that rises to the left with respect to the rotation axis direction of the developing sleeve. The developing sleeve forms fine grooves densely by a cutting machine according to the number of rotations of the cutting tool, the feeding speed of the cutting tool, and the rotating speed of the sleeve. Since the groove shape of the dent provided on the surface is slanted, when this developing sleeve rotates downward in the figure, the developer is blown off in the direction of the arrow in the figure at the developer separating portion of the developer, and the developer carrying member A developer conveying force is generated on one end side (left side in the drawing) in the rotation axis direction. If the direction in which the conveying force by the developer carrying member is generated is the same as the direction in which the developer is stirred and conveyed by the stirring and conveying member, energy can be reduced by suppressing the rotation speed of the stirring and conveying member. Further, if the rotation speed of the stirring and conveying member is maintained, there is an advantage that density unevenness can be reduced.

  However, in the developing sleeve disclosed in Patent Document 3, the developer is caused by one end side (left side in FIG. 23) in the rotation axis direction of the developing sleeve, that is, the elliptical recess in the rotation axis direction of the developing sleeve. The downstream side of the conveyance force generated in the conveyance direction is a direction in which a large amount of developer is accumulated. Further, since the developer separates toward one end side (left end portion side) of the developing sleeve at the agent separation portion, the detached developer tends to enter the end portion side and the developer is easily generated. Further, there is a possibility that image density unevenness occurs due to the accompanying developer.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to convey a two-component developer in the rotation axis direction by a plurality of oval or elliptical recesses formed obliquely on the outer peripheral surface. When a developer carrying member is used, a developing device capable of suppressing the enlargement of the device and preventing unevenness in image density due to the accompanying rotation of the two-component developer on the surface of the developer carrying member, and image formation provided with the developing device An apparatus and a process cartridge are provided.

In order to achieve the above object, 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, and the magnetic force of the magnetic field generating means A developer carrying member that carries and conveys a two-component developer containing a magnetic carrier and toner on the outer peripheral surface; a developer containing unit that contains the two-component developer carried on the developer carrying member; An agitating and conveying member that conveys the two-component developer along the rotation axis direction of the developer carrying member while stirring, and a developer regulating member that regulates the layer thickness of the two-component developer carried on the developer carrying member A development region facing the latent image carrier after the two-component developer carried on the developer carrier by the magnetic force of the magnetic field generating means is regulated by the developer regulating member from within the developer container And return to the developer container. In the developing device, the magnetic field generating means includes a magnetic field generating member having an agent separating magnetic pole for generating a magnetic force for separating the two-component developer after passing through the developing area from the developer carrier. The hollow body of the developer carrier has an oval or elliptical recess on its outer peripheral surface, and the longitudinal direction of the recess is oblique with respect to the rotation axis direction of the developer carrier. And a plurality of the two-component developer are distributed so as to be distributed at intervals from each other, and is generated by the movement of the outer peripheral surface having the concave portion of the hollow body at a position where the two-component developer is separated from the developer carrier. A means for suppressing the movement of the two-component developer toward one end in the rotation axis direction of the developer carrying member is provided.
According to a second aspect of the present invention, in the developing device according to the first aspect, support shafts made of a magnetic material extending from the main body portion of the magnetic field generating member to the outer side in the longitudinal direction are provided at both longitudinal ends of the magnetic field generating member. The support shafts at both ends of the magnetic field generating member have different lengths in the longitudinal direction, and have the concave portion of the hollow body at a position where the two-component developer is separated from the developer carrier. The length of one support shaft of the magnetic field generating member on the downstream side in the moving direction of the two-component developer in the rotation axis direction of the developer carrier generated by the movement of the outer peripheral surface is the other of the magnetic field generating members. It is characterized by being shorter than the support shaft.
The invention of claim 3 is caused by the movement of the outer peripheral surface having the concave portion of the hollow body at a position at which the two-component developer is separated from the developer carrier in the developing device of claim 1 or 2. The agent separation pole and the agent separation pole so as to face the agent separation pole through the hollow body at the end of the magnetic field generating member on the downstream side in the moving direction of the two-component developer in the rotation axis direction of the developer carrier. The magnetic field generating means having the same magnetic pole is provided.
According to a fourth aspect of the present invention, in the developing device of the third aspect, the magnetic field generating means having a magnetic pole having the same polarity as the agent separating pole is provided at both end portions of the magnetic field generating member in the rotation axis direction of the developer carrying member. The two-component developer moves in the direction of the axis of rotation of the developer carrier generated by the movement of the outer peripheral surface of the hollow body having the concave portion. The magnetic force on the outer peripheral surface of the hollow body generated by the magnetic field generating means on the downstream side in the direction is stronger than the magnetic force generated on the magnetic field generating means on the upstream side in the moving direction of the two-component developer. To do.
According to a fifth aspect of the present invention, in the developing device according to any one of the first to fourth aspects, the agent separating magnetic pole includes a first magnetic pole and a second magnetic pole having the same polarity adjacent to each other. To do.
According to a sixth aspect of the present invention, a latent image bearing member and a latent image on the latent image bearing member are conveyed by conveying a two-component developer containing a magnetic carrier and a toner to a developing region facing the latent image bearing member. And a developing device that develops the toner by adhering to the toner, and the toner image obtained by the development by the developing device is finally transferred from the latent image carrier onto the recording material, thereby recording the recording material. In a process cartridge that is detachable from an image forming apparatus that forms an image on a material, the developing device is any of the developing devices according to any one of claims 1 to 5.
According to a seventh aspect of the present invention, there is provided a latent image bearing member and a latent image on the latent image bearing member by transporting a two-component developer containing a magnetic carrier and a toner to a developing region facing the latent image bearing member. And a developing device that develops the toner by adhering to the toner, and the toner image obtained by the development by the developing device is finally transferred from the latent image carrier onto the recording material, thereby recording the recording material. An image forming apparatus comprising a process cartridge that is detachable from an image forming apparatus that forms an image on a material, wherein the process cartridge is a process cartridge according to claim 6.
According to an eighth aspect of the invention, in the image forming apparatus of the seventh aspect, a plurality of the process cartridges are provided.
According to a ninth aspect of the present invention, in the image forming apparatus according to the seventh or eighth aspect, the toner has a volume average particle diameter of 3 μm or more and 8 μm or less, and a volume average particle diameter (Dv) and a number average particle diameter (Dn). ) And a toner having a ratio (Dv / Dn) in the range of 1.00 to 1.40.
According to a tenth aspect of the present invention, in the image forming apparatus according to the seventh, eighth, or ninth aspect, the toner has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. The toner is in the range.

  In the present invention, the developer carrying member has an oval or elliptical concave portion on the outer peripheral surface of a sleeve-like hollow body made of a non-magnetic member and capable of being driven to rotate, and its longitudinal direction is the rotation of the developer carrying member. A plurality are provided so as to be obliquely inclined with respect to the axial direction and distributed at intervals. By rotating the hollow body in which the oval or elliptical concave portion is formed on the outer peripheral surface, a conveyance force for moving the two-component developer to one end side in the rotation axis direction of the developer carrier is generated. . Here, the movement of the two-component developer toward one end in the rotation axis direction of the developer carrier is suppressed at a position where the two-component developer is separated from the developer carrier. This causes the two-component developer to move along with the outer peripheral surface of the hollow body of the developer carrier on one end side in the rotation axis direction of the developer carrier. Therefore, it is possible to prevent image density unevenness due to the accompanying rotation of the two-component developer on the surface of the developer carrying member. In addition, since the rotation of the two-component developer is less likely to occur, the rotation shaft of the developer carrier is secured in order to secure a region for the rotation of the two-component developer at both ends in the rotation axis direction of the developer carrier. It is not necessary to lengthen in the direction, and the increase in size of the apparatus can be suppressed.

  According to the present invention, when a developer carrying member that generates a conveying force of a two-component developer in the direction of the rotation axis by a plurality of oval or elliptical recesses formed obliquely on the outer peripheral surface is used, the apparatus is large. The present invention has an excellent effect that the image density unevenness due to the accompanying rotation of the two-component developer on the surface of the developer carrying member 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 an end mill for forming the recess shown in FIG. FIG. 3 is an explanatory diagram schematically showing the shape of a toner for explaining a shape factor SF-1. FIG. 3 is an explanatory diagram schematically showing the shape of a toner for explaining a shape factor SF-2. 1 is a schematic configuration diagram showing an example of a conventional general developing device. FIG. 10 is a schematic configuration diagram illustrating an example of another conventional developing device. FIG. 6 is an explanatory diagram showing the behavior of the developer on the surface of the developing sleeve. (a) is explanatory drawing which showed distribution of normal direction magnetic flux density (absolute value) on the surface of a developing sleeve. FIG. 5B is an explanatory view of the behavior of the developer in the central portion (image forming region portion) of the developing sleeve as viewed from the cross-sectional direction. (C) is an explanatory view of the behavior of the developer at the end of the developing sleeve (outside the image forming region) as seen from the cross-sectional direction. Explanatory drawing which looked at the behavior of the developer in the edge part (outside image formation area) of the developing sleeve from the side surface direction. FIG. 3 is an enlarged view of the surface of a developing sleeve in which an elliptical concave portion (dent) is provided so as to have an upwardly inclined angle with respect to the longitudinal direction. (A) is sectional drawing which looked at the developing roller from the side. (B) is an enlarged view of the surface of the developing sleeve. Explanatory drawing of the developing device which has arrange | positioned the magnet. (A) is a figure for demonstrating arrangement | positioning of a magnet regarding the developing sleeve rotating shaft direction. (B) is an enlarged view of the surface of the developing sleeve. The figure which shows the installation range of the magnet in the magnetic force distribution of a cross section. The side view of the developing roller which shows the flow of the developer of the developing sleeve left end side by a magnet. (A) is a figure for demonstrating the position of the magnet arrange | positioned additionally regarding the developing sleeve rotating shaft direction. (B) is an enlarged view of the surface of the developing sleeve. Explanatory drawing of the developing device which concerns on other embodiment.

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 the embodiment 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. 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 as an intermediate transfer member, 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 unit, a photosensitive drum 108 as an image carrier, and a cleaning blade 112 as a cleaning device. And a developing device 113.

  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 at a distance from a later-described developing roller 115 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 developer regulating member.

  The developer supply unit 114 includes a developer storage tank 117 as a developer storage unit and a pair of agitation screws 118 as an agitation transport member. The developer storage tank 117 is formed in a box shape that is substantially the same length as the photosensitive drum 108. A partition wall 119 extending along the longitudinal direction of the developer storage tank 117 is provided in the developer storage tank 117. The partition wall 119 partitions the developer 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 developer storage tank 117 stores a two-component developer (hereinafter simply referred to as “developer”) in both the first space 120 and the second space 121. The developer contains toner and a magnetic carrier (magnetic powder) as magnetic particles. The toner is appropriately supplied by the toner replenishing device 136 to one end of the first space 120 on the side of the first space 120 and the second space 121 that is away from the developing roller 115. The toner is, for example, spherical fine particles produced by an emulsion polymerization method or a suspension polymerization method.

  As the toner of this embodiment, the volume average particle size of the toner is preferably 3 to 8 μm in order to reproduce minute dots of 600 dpi or more. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.40. The closer this ratio (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

  Further, as the toner of this embodiment, it is preferable that the shape factor SF-1 is in the range of 100 to 180, and the shape factor SF-2 is in the range of 100 to 180. 17 and 18 are diagrams schematically showing the shape of the toner for explaining the shape factor SF-1 and the shape factor SF-2, respectively. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4. When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.

  SF-1 = {(MXLNG) 2 / AREA} × (100π / 4) Expression (1)

  The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100π / 4. When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.

  SF-2 = {(PERI) 2 / AREA} × (100π / 4) Expression (2)

Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.
When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

  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 developer storage tank 117, the developing roller 115, and the photosensitive drum 108. The agitating screw 118 is provided so as to be rotatable around the 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 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 the second space 121 from the other end. It conveys to the other end part. 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 developer storage tank 117 of the developer supply unit 114 described above, and covers the developing roller 115 and the like together with the developer 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 developer 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.

  2 and 3, the developing roller 115 includes a magnet roller shaft (core metal) 134 as a support shaft, a magnet roller 133 as a magnetic field generating member that is a cylindrical magnet body, and a sleeve shape (cylindrical shape). And a developing sleeve 132 as a hollow body. The magnet roller shaft 134 is a fixed shaft whose axial direction (longitudinal direction) is arranged parallel to the longitudinal direction of the photosensitive drum 108 and is fixed to the case 125 without rotating.

  The magnet roller 133 is made of a magnetic material and is formed in a cylindrical shape, and a plurality of fixed magnetic poles (not shown) are attached to the magnet roller 133. The magnet roller 133 is fixed to the outer periphery of the magnet roller shaft 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 rotation axis direction (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 is accommodated (enclosed) in the developing sleeve 132.

  One fixed magnetic pole is opposed to the agitating screw 118 described above. This fixed magnetic pole forms 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 developer containing 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 a 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 developer storage tank 117.

  When the developer is adsorbed to the outer surface of the developing sleeve 132, the fixed magnetic poles described above are erected on the outer surface of the developing sleeve 132 by stacking a plurality of magnetic carriers of the developer along the magnetic lines of force generated by the fixed magnetic poles. 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.

  The developing sleeve 132 is formed in a cylindrical shape as shown in FIG. 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 subjected to a roughening process on the outer surface by, for example, the surface processing apparatus 1 shown in FIG.

  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, for example. The length of the developing sleeve 132 in the axial (axial center) direction is desirably about 300 mm to 350 mm, for example, 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 peripheral surface of the developing sleeve 132 is provided with a large number of recesses 139 that are 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 recesses 139 are regularly arranged when the intervals between the recesses 139 adjacent to each other in the circumferential direction and the rotation axis direction of the developing sleeve 132 are constant. . That is, the interval between the recesses 139 adjacent to each other in the circumferential direction and the rotation axis direction of the developing sleeve 132 is constant.

  Further, the recess 139 is disposed in a state where the longitudinal direction thereof is along the rotation axis 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 rotation axis direction of the developing sleeve 132. In the illustrated example, the longitudinal direction of the recess 139 is slightly inclined with respect to the rotation axis direction of the developing sleeve 132 and is arranged substantially in parallel. As described above, in this embodiment, the longitudinal direction of the recess 139 is arranged in parallel or substantially parallel to the rotation axis direction of the developing sleeve 132, and the longitudinal direction of the recess 139 is parallel to the rotation axis direction of the developing sleeve 132. It is said that it is arranged in.

  Further, as shown in FIGS. 5, 6 (a), and 7, a plurality of the recesses 139 are arranged along the rotation axis direction of the developing sleeve 132 and are arranged in the circumferential direction of the developing sleeve 132. Adjacent ones are arranged so as to be displaced by about half of the length of the recess 139. Further, since the recesses 139 are formed on the outer surface of the developing sleeve 132 by the surface treatment apparatus 1 shown in FIG. 8A, they are arranged on the outer surface of the developing sleeve 132 on a spiral indicated by a one-dot chain line in FIG. Has been placed.

  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 rotation axis direction of the developing sleeve 132) is formed in 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 rotation axis 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 scrapes off the developer on the outer surface of the developing sleeve 132 exceeding a desired thickness into the developer containing tank 117 and transports the developer on the outer surface of the developing sleeve 132 to the developing region 131. To the desired thickness.

  In the developing device 113 configured as described above, the developer and the magnetic carrier are sufficiently stirred by the developer supply unit 114, and the stirred developer is adsorbed 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 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 separates the developed developer toward the developer storage tank 117. Further, the developed developer accommodated in the developer accommodating tank 117 is sufficiently agitated with another developer in the second space 121 again, and the electrostatic latent image of the photosensitive drum 108 is Used for development. Note that when the toner supply sensor 114 (described later) detects that the concentration of toner supplied to the photosensitive drum 108 is lowered by the developer supply unit 114, for example, the developer supply unit 114 moves to the development device 113 by the operation of the toner supply device 136. Toner is discharged.

  The image forming apparatus 101 having the above configuration forms an image on the recording paper 107 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 having the above configuration, 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 means (not shown) controls the toner supply device 136 so as 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, the surface treatment apparatus 1 that forms the recess 139 on the outer surface of the developing sleeve 132 will be described. 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 described above, the developing sleeve 132 before the recess 139 is formed between the chuck pins 11 and 15 is positioned in a state where the slide holding unit 8 is separated from the fixed holding unit 7. In this state, 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 so that the developing sleeve 132 is sandwiched between the chuck pins 11 and 15. Thus, 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 rotation axis direction (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 rotation axis direction of the developing sleeve 132 is determined by the radius of curvature of the outer edge of the cutting blade 24, and the depth of the recess 139 is determined by the cutting depth of the cutting blade 24. Thus, the interval between the recesses 139 in the rotation axis 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 (3), the motor 2 as the rotational 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]] (3)

  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, a process of manufacturing the developing sleeve 132 by cutting the outer surface of the developing sleeve 132 using the surface treatment apparatus 1 having the above-described 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 direction of the rotation axis 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 and 15 of the holding portions 7 and 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.

  According to the present embodiment, there is no convex portion formed by conventional sandblasting on the outer surface, and the concave portion 139 is formed into a larger concave portion 139, so that the concave portion 139 is less likely to be worn even with aging. Therefore, it is possible to suppress a decrease in the transport amount of the developer due to secular change.

  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 long in the direction of the rotation axis are regularly arranged on the outer surface of the developing sleeve 132, and the total volume of the recesses 139 is 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.

  Further, since the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 are displaced in the rotation axis direction of the developing sleeve 132, a portion where the recess 139 is not formed on the outer surface of the developing sleeve 132 or the recess 139 is formed. It can prevent that many places etc. arise. 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 developing sleeve 132 described above, the circumferential section of the recess 139 is formed in a V shape, but the recess 139 is formed as shown in FIGS. 9A to 9C. The circumferential section of the developing sleeve 132 may be formed in an arc shape. In the illustrated example, both the circumferential direction and the rotation axis 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. In FIGS. 9 to 11, the same parts as those in the above-described embodiment will be described with the same reference numerals.

  In the cases shown in FIGS. 9 to 11, the developing sleeve 132 of the recess 139 is formed in a circular arc shape in both the rotation axis direction and the circumferential direction, so that the developer that can be accommodated in the recess 139 can be obtained. A sufficient amount of developer that can be increased can be conveyed.

  Further, in the example of the developing sleeve 132 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 by appropriately changing the shape of the outer edge 25 of the cutting blade 24, FIG. As shown in FIG. 13, the circumferential sectional shape of the developing sleeve 132 of the recess 139 may be changed as appropriate. 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. In FIG. 12 and FIG. 13, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

  Further, in the example of forming the recess 139 of the developing sleeve 132 described above, the motors 2 and 20 and the actuator are operated simultaneously and continuously, the recess 139 is spirally arranged on the outer surface of the developing sleeve 132, and each recess is formed. 139 is slightly curved in an arcuate shape, but 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 in the direction of the rotation axis of the developing sleeve 132. And the plurality of recesses 139 may be arranged on a straight line along the circumferential direction of the developing sleeve 132.

  Furthermore, in the example of the developing sleeve 132 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 in the above-described embodiment is used. As shown in FIG. 16A, 139 may be formed in a circular shape in plan view.

  In the image forming apparatus 101, 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, in the image forming apparatus, 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. Also good. The image forming apparatus 101 includes process cartridges 106Y, 106M, 106C, and 106K that are detachable from the apparatus main body 102. However, the image forming apparatus 101 only needs to include the developing device 113 and does not necessarily include the process cartridges 106Y, 106M, 106C, and 106K.

Next, the developing roller 115 will be described in more detail.
FIG. 24A is a cross-sectional view of the developing roller as viewed from the side, and FIG. 24B is an enlarged view of the surface of the developing sleeve. The illustrated developing roller is a general and inexpensive developing roller in the two-component developing system.

  In FIG. 24 (a), as described above, the magnet roller shaft 134, which is the shaft member of the developing roller 115, has the case 125 (non-rotating state) in a state where the magnet roller 133 is fixed to the outer periphery without rotating around the axis. (Not shown) without being rotated. The magnet roller 133 is provided with a plurality of fixed magnetic poles, for example, a magnetic pole S1, a magnetic pole N1, a magnetic pole S2, a magnetic pole N2 as a first magnetic pole, and a magnetic pole N3 as a second magnetic pole. The first magnetic pole N <b> 2 and the second magnetic pole N <b> 3 are agent separation magnetic poles for generating a magnetic force that causes the developer after having passed through the development region to leave the developing sleeve 132. Then, by restricting the angle around the axis of the magnet roller shaft 134 and fixing the magnet roller shaft 134 to the case 125, the rotation direction angle with respect to the developing unit can be determined, and the position of the main pole in the developing nip portion can be determined.

  Bearings 135a and 135b are respectively disposed on the right end portion 134a and the left end portion 134b of the magnet roller shaft 134, and these bearings rotatably support the right flange 132a and the left flange 132b, respectively. Since the right flange 132a and the left flange 132b are fixed inside the both ends of the developing sleeve 132, the developing sleeve 132 rotates around the axis of the magnet roller shaft 134 by rotating the rotating shaft 132c of the left flange 132b. It becomes free to rotate.

  In the magnet roller shaft 134, the tip end portion of the right end portion 134a is fixed to the case 125 (not shown). Therefore, the length of the magnet roller shaft 134 existing outside the both end portions of the magnet roller 133 is the length of the right end portion 134a. The length L2 of the left end portion 134b is shorter than the length L1.

  The magnet roller shaft 134 is formed of a metal material made of a magnetic material (magnetic member). The right end portion 134a and the left end portion 134b that extend outward from the end face in the axial direction (longitudinal direction) of the main body portion of the magnet roller 133 of the magnet roller shaft 134 have different axial lengths. In the illustrated example, the length of the right end portion 134a is longer than that of the left end portion 134b. As described above, the right end portion 134a and the left end portion 134b of the magnet roller 133 have different lengths, so that the N2 pole (agent separating upstream pole) and the N3 pole (pumping pole = agent separating downstream pole) at both ends of the magnet roller 133 are obtained. The distribution of the magnetic field is different between the regions on the developing sleeve 132 facing each other. For this reason, the right end magnetic field T1 formed on the right end portion 134a side is formed so as to draw a large arc including the flowing-in magnetic field as compared with the left end portion magnetic field T2 formed on the left end portion 134b side. Accordingly, the degree of allowance for showing the margin until the developer is accompanied is low on the right end side of the developing sleeve 132 and high on the left end side.

  In the developing sleeve 132 of the present embodiment, in consideration of the influence of the right end magnetic field T1 and the left end magnetic field T2, an elliptical recess 139 is formed at an oblique angle with respect to the rotation axis direction of the developing sleeve 132. It is provided on the surface of the developing sleeve 132. That is, as shown in FIG. 24 (b), the left end of the shorter side of the magnet roller shaft 134 that is outside the both ends in the longitudinal direction of the magnet roller 133 at the agent separating portion for releasing the developer from the surface of the developing sleeve. The angle in the short direction of the ellipse of the recess 139 is set so that the developer is released toward the part side. With such a configuration, on the left end portion 134b side, the developer is affected by the magnetic field T2 of the left end portion 134b, the trajectory is corrected so as to face the inside (right side) of the image forming region, and the developer falls. . On the other hand, on the side of the right end portion 134a where the margin of developer revolving is low due to the influence of the magnetic field T1 of the right end portion 134a, the developer leaves in the direction of the arrow in FIG. Fall towards the. Accordingly, it is possible to minimize the state of the developer accompanying the both ends of the developing sleeve 132, and to suppress the longitudinal dimension width of the developing roller 115.

  In the developing device according to the present embodiment, as shown in FIG. 25, a magnet 149 serving as a magnetic field generating unit may be disposed so as to face the agent separating portion at a position where the developer is separated from the developing sleeve 132. Good. The illustrated example is an example of a low-stress type developing device having a single pumping / developing doctor pole, but the same position is used in a conventional developing device (see FIG. 19) that has a different pumping and doctoring pole. The same effect can be obtained by disposing the magnet 149 on the surface.

  The magnet 149 is arranged at a facing position facing the N2 pole and N3 pole, which are agent separating magnetic poles (agent separating opposing poles) via the developing sleeve 132, so that the N pole of the magnet 149 faces the developing roller 115 side. ing. Further, as shown in FIG. 26A, the magnet 149 is disposed at a position where the position in the developing sleeve rotation axis direction is outside the left end portion in the longitudinal direction of the magnet roller 133. As shown in FIG. 26 (b), the position where the magnet 149 is disposed is the position facing the agent separating portion on both ends of the developing sleeve 132 in the rotational axis direction, as shown in FIG. This is the position on the end side where the developer conveying force is generated by the recess 139 with respect to the rotation axis direction of the developing sleeve.

  FIG. 27 is a diagram showing the relationship between the magnetic force distribution on the surface of the developing sleeve 132 and the installation range of the magnet 149. The installation range of the magnet 149 is such that the position in the developer conveying direction by the developing sleeve 132 is the normal direction by the N3 pole on the developing sleeve from the normal line H1 of the maximum normal direction magnetic flux density by the N2 pole on the developing sleeve. It is between the normal H2 of the maximum point of magnetic flux density. Incidentally, in the conventional developing device (see FIG. 19) that is pumped up and the doctor pole is a separate pole, the installation range of the magnet 149 is from the normal of the maximum normal direction magnetic flux density by the S2 pole on the developing sleeve, This is up to the normal of the maximum point of the magnetic flux density in the normal direction by the S3 pole on the developing sleeve.

  The magnet 149 is a rotating shaft in the agent separation region on the developing sleeve 132 that causes the developer on the developing sleeve to exert a peeling force toward the direction away from the developing sleeve 132 by the magnetic force of the N2 pole and N3 pole as the agent separating magnetic pole. A magnetic field is generated that displaces the magnetic lines of force passing through the direction end region inward in the rotational axis direction. Specifically, the position of the magnetic pole surface of the same polarity (N pole) as the N2 pole and the N3 pole is the maximum point of the normal direction magnetic flux density by the N2 pole on the developing sleeve 132 in the developer transport direction by the developing sleeve. Between the normal line H1 and the normal line H2 at the maximum point of the normal direction magnetic flux density by the N3 magnetic pole on the developing sleeve 132, with respect to the rotation axis direction of the developing sleeve 132, the longitudinal end of the main body portion of the magnet roller 133 The magnet 149 is arranged so as to be outside the portion. As a result, as described above, the direction of the lines of magnetic force in the end region in the developing sleeve rotation axis direction in the agent separation region on the developing sleeve 132 in the region facing the magnet roller 133 is orthogonal to the developing sleeve rotation axis direction. You can get closer to the direction. As a result, the peeling force in this end region is improved, so that the peeling force can be effectively applied to the developer also in this end region, and the developer can be efficiently separated from the outer peripheral surface of the developing sleeve 132. As a result, it is possible to reduce the width (the length in the developing sleeve rotation axis direction) in which the developer accompanies the region facing the magnet roller 133. Therefore, even if the width of the opposing region of the magnet roller 133 is shortened, the same effective development width as that in the past can be realized without causing uneven image density due to the accompanying rotation of the developer. Miniaturization can be achieved.

  Further, in the present embodiment, the development carried on the outer peripheral surface portion of the developing sleeve where the shortest distance X (see FIG. 27) between the N-pole magnetic pole surface of the magnet 149 and the outer peripheral surface of the developing sleeve 132 is the shortest distance. It is comprised so that it may become larger than the height of an agent. With such a configuration, when the developing sleeve 132 is rotating, the developer on the developing sleeve is not kicked by the magnetic force of the magnet 149, and a targeted effect such as agent separation can be obtained without any harmful effects.

  FIG. 28 is a side view of the developing roller 115 and shows the flow of the developer on the left end side of the developing sleeve by the magnet 149. Due to the magnetic force of the magnet 149, the developer TC that has turned around the surface of the developing sleeve corresponding to the position outside the left end portion of the magnet roller is brought directly below or inside the image forming area, and further, the agent separation upstream pole and the agent separation downstream pole With the normal magnetic force, the developer TC is separated from the developing sleeve 132 and dropped into the developer storage tank, so that the rotation of the developer can be eliminated.

The magnet 149 may be arranged on the right end side in addition to the left end side in the developing sleeve rotation axis direction.
FIG. 29A is an explanatory diagram in which a magnet 150 as a second magnetic field generating means is further arranged at a position where the position in the developing sleeve rotation axis direction is outside the right end in the longitudinal direction of the magnet roller 133. FIG. 4B is an enlarged view of the surface of the developing sleeve. By arranging the magnet 150 as the second magnetic field generating means on the right end side in addition to the magnet 149 on the left end side, the accompanying rotation of the developer on the right end side of the developing sleeve can be eliminated.

  Here, the magnetic force of the magnet 149 on the left end side may be made stronger than the magnetic force of the magnet 150 on the right end side. On the left end side, since the developer 139 is provided on the surface of the developing sleeve 132, a developer carrying force in the left end side direction is generated in the developer separation portion. Therefore, by increasing the magnetic force of the magnet 149 on the left end side, Therefore, it is possible to regulate the developer to be conveyed to the both ends and improve the agent separating property on both end sides substantially evenly.

The present invention can be applied not only to the developing device having the above-described configuration but also to a developing device having another configuration.
FIG. 30 shows an example of a developing device according to another embodiment of the present invention.
The developing device of the illustrated example is disposed so as to face a developer carrier 341 in which a plurality of magnetic poles are formed around by a magnetic field generating means 347 arranged inside, and to face the lower side of the developer carrier 341. A developer regulating member 346 that regulates the amount of the developer carried on the developer carrying member 341, and two conveying members that convey the developer contained in the apparatus in the longitudinal direction to form a circulation path. I have. The plurality of transport members are disposed substantially opposite to the developer carrier 341, and a first developer transport member 342 that supplies the developer to the developer carrier 341 while transporting the developer in the longitudinal direction. The developer carrying member 341 is opposed to the developer carrying member 341 and has a second developer carrying member 343 that mixes and stirs the developer and the replenishment toner, and the developer is circulated and conveyed in one direction. The developing device includes a partition member 344 that restricts the passage of the developer between one developer conveying member 342 and the second developer conveying member 343. By applying the present invention to the developing device having such a configuration, it is possible to improve the margin around the end portion on the side where the developer volume on the developer recovery side is high, and to exert a greater effect.

As described above, according to the present embodiment, the magnet roller 133 has the magnet roller shafts 134 as support shafts made of a magnetic material extending from the main body portion of the magnet roller 133 in the longitudinal direction at both ends in the longitudinal direction. The magnet roller shafts 134 have different lengths in the longitudinal direction. One magnet roller on the downstream side in the developer moving direction in the direction of the developing roller rotation axis generated by the movement of the outer peripheral surface having the recess 139 of the developing sleeve 132 at the position of the agent separating portion where the developer is separated from the developing roller 115. The length of the shaft 134b is shorter than the other magnet roller shaft 134a. With this configuration, on the one magnet roller shaft 134b side, the developer is affected by the magnetic field T2 of the magnet roller shaft 134b and the trajectory is corrected so as to face the inside of the image forming area, and then dropped. On the other hand, due to the influence of the magnetic field T1 of the other magnet roller shaft 134a, the developer falls toward the inside of the image forming area on the side of the other magnet roller shaft 134a with a low margin of the accompanying developer. Accordingly, it is possible to minimize the state of the developer accompanying the both ends of the developing sleeve 132 and to suppress the longitudinal dimension of the developing roller 115.
Further, according to the present embodiment, the magnet roller on the downstream side in the developer moving direction in the developing roller rotation axis direction generated by the movement of the outer peripheral surface having the recess 139 of the developing sleeve 132 at a position where the developer is separated from the developing roller 115. A magnet as a magnetic field generating means having a magnetic pole of the same polarity as the agent separation pole (N2 pole, N3 pole) so as to face the agent separation pole (N2 pole, N3 pole) via the developing sleeve 132 at the end of 133 149 may be provided. The magnet 149 has an end region in the rotational axis direction in the agent separation region on the developing sleeve that causes the developer on the developing sleeve 132 to exert a peeling force toward the direction away from the developing sleeve 132 by the magnetic force of the N2 pole and the N3 pole. A magnetic field is generated that displaces the passing magnetic field lines inward in the rotation axis direction. Specifically, the position of the magnetic pole surface having the same polarity (N pole) as the N2 pole and N3 pole is the normal line by the N2 pole on the developing sleeve 132 with respect to the developer transport direction (sleeve surface moving direction) by the developing sleeve 132. Between the normal line H1 at the maximum point of the directional magnetic flux density and the normal line H2 at the maximum point of the normal magnetic flux density by the N3 magnetic pole on the developing sleeve 132, the main body of the magnet roller 133 in the developing sleeve rotation axis direction. The magnet 149 is arranged so as to be outside the end portion in the longitudinal direction of the portion. As a result, as described above, the direction of the lines of magnetic force in the end region in the developing sleeve rotation axis direction in the agent separation region on the developing sleeve 132 in the region facing the magnet roller 133 is orthogonal to the developing sleeve rotation axis direction. You can get closer to the direction. Accordingly, the peeling force in this end region is improved, so that the peeling force can be effectively applied to the developer also in this end region, and the developer can be efficiently separated from the outer peripheral surface of the developing sleeve 132. As a result, it is possible to reduce the width (the length in the direction of the developing roller rotation axis) in which the developer is accompanied in the region facing the magnet roller 133. Therefore, even if the width of the opposing region of the magnet roller 133 is shortened, the same effective development width as that in the past can be realized without causing uneven image density due to the accompanying rotation of the developer. Miniaturization can be achieved.
In addition, according to the above-described embodiment, the other end of the developing sleeve 132 on the outer peripheral surface of the developing sleeve 132 on the upstream side in the rotation axis direction on the upstream side of the developer conveying direction by the developing sleeve 132 with respect to the doctor blade 116. A magnet 150 as a second magnetic field generating means having the same polarity as the agent separation pole (N2 pole, N3 pole) may be further provided at the side position so as to face the agent separation pole (N2 pole, N3 pole). Good. By providing a magnet 150 not only on one end side but also on the other end side of the magnet roller 133 on the downstream side in the developer moving direction in the direction of the developing roller rotation axis, the developer on the other end side is brought together. Rotation can also be prevented. Here, the magnetic force of the magnet 149 is preferably stronger than the magnetic force of the recording magnet 150. In this case, when the developer leaves the elliptical recess 139 of the developing sleeve 132, movement of the developer that is about to be conveyed to the one end side in the direction of the developing roller rotation axis by the recess 139 is restricted. Thus, it is possible to improve the agent separating properties on both end sides substantially equally.
Further, according to the embodiment, the volume average particle diameter of the toner constituting the developer is 3 to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is in the range of 1.00 to 1.40. In order to reproduce minute dots of 600 dpi or more, the closer the (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.
Further, according to the embodiment, the toner constituting the developer has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. When the value of SF-1 is 100, the shape of the toner is a true sphere, and becomes larger as the value of SF-1 increases. When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the SF-2 value increases, the unevenness of the toner surface becomes more prominent. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

101 Image forming devices 106Y, 106M, 106C, 106K Process cartridge 108 Photoconductor drum 109 Charging roller 113 Developing device 114 Developer supplying unit 115 Developing roller 116 Doctor blade 117 Developer storing tank 118 Stir screw 125 Case 131 Developing region 132 Developing sleeve 133 Magnet roller 134 (134a, 134b) Magnet roller shaft 139 Recess 149, 150 Magnet TC Developer

JP 2007-183533 A JP 2009-251036 A JP 2009-80447 A

Claims (10)

A two-component developer having a magnetic field generating means disposed in a sleeve-like hollow body made of a non-magnetic member and capable of being driven to rotate, and having 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 carrier that carries and conveys
A developer accommodating portion for accommodating a two-component developer carried on the developer carrying member;
An agitating and conveying member for conveying the two-component developer along the rotation axis direction of the developer carrying member while stirring the two-component developer;
A developer regulating member that regulates the layer thickness of the two-component developer carried on the developer carrying body,
The two-component developer carried on the developer carrying member by the magnetic force of the magnetic field generating means from the inside of the developer containing portion is allowed to pass through the developing region facing the latent image carrier after being regulated by the developer regulating member, A developing device for returning the developer into the developer container;
The magnetic field generating means has a magnetic field generating member having an agent separating magnetic pole for generating a magnetic force for separating the two-component developer after passing through the developing region from the developer carrier.
The hollow body of the developer carrier has an oval or elliptical recess on its outer peripheral surface, and the longitudinal direction of the recess has an oblique angle with respect to the rotation axis direction of the developer carrier. It is provided in plural so that it is distributed at intervals.
The two-component developer toward the one end side in the rotation axis direction of the developer carrier generated by the movement of the outer peripheral surface having the concave portion of the hollow body at a position where the two-component developer is separated from the developer carrier. An image forming apparatus comprising means for suppressing movement of a component developer. The developing device according to claim 1.
At both ends in the longitudinal direction of the magnetic field generating member, there are support shafts made of a magnetic body extending outward in the longitudinal direction from the main body portion of the magnetic field generating member,
The support shafts at both ends of the magnetic field generating member have different lengths in the longitudinal direction,
Downstream of the two-component developer in the direction of the rotation axis of the developer carrier generated by the movement of the outer peripheral surface of the hollow body having the concave portion at a position where the two-component developer is separated from the developer carrier. A developing device, wherein the length of one support shaft of the magnetic field generating member on the side is shorter than the other support shaft of the magnetic field generating member. The developing device according to claim 1 or 2,
Downstream of the two-component developer in the direction of the rotation axis of the developer carrier generated by the movement of the outer peripheral surface of the hollow body having the concave portion at a position where the two-component developer is separated from the developer carrier. And a magnetic field generating means having a magnetic pole having the same polarity as the agent separating pole so as to face the agent separating pole via the hollow body at the end of the magnetic field generating member on the side . The developing device according to claim 3.
Magnetic field generating means having magnetic poles of the same polarity as the agent separating pole are respectively arranged so as to face the agent separating pole through the hollow body at both ends of the magnetic field generating member in the rotation axis direction of the developer carrier. Provided,
On the outer peripheral surface of the hollow body generated by the magnetic field generating means on the downstream side in the moving direction of the two-component developer in the rotation axis direction of the developer carrier generated by the movement of the outer peripheral surface having the concave portion of the hollow body Is stronger than the magnetic force generated by the magnetic field generating means on the upstream side in the moving direction of the two-component developer. In the developing device according to any one of claims 1 to 4,
The developing device according to claim 1, wherein the agent separating magnetic pole is composed of a first magnetic pole and a second magnetic pole having the same polarity adjacent to each other. A latent image carrier and a two-component developer containing a magnetic carrier and toner are conveyed 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. Image formation in which an image is formed on the recording material by integrally supporting the developing device and finally transferring the toner image obtained by development by the developing device from the latent image carrier onto the recording material In process cartridges that are detachable from the device,
6. A process cartridge according to claim 1, wherein the developing device is the developing device according to claim 1. A latent image carrier and a two-component developer containing a magnetic carrier and toner are conveyed 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. Image formation in which an image is formed on the recording material by integrally supporting the developing device and 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 apparatus,
The image forming apparatus according to claim 6, wherein the process cartridge is the process cartridge according to claim 6. The image forming apparatus according to claim 7.
An image forming apparatus comprising a plurality of the process cartridges. The image forming apparatus according to claim 7 or 8,
The toner has a volume average particle diameter of 3 μm or more and 8 μm or less, and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is in the range of 1.00 to 1.40. An image forming apparatus comprising a toner. The image forming apparatus according to claim 7, 8 or 9.
The image forming apparatus, wherein the toner has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180.

Images