JP5504711B2 - Developing roller, developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing roller, a developing device, a process cartridge, and an image forming apparatus used in a copying machine, a facsimile machine, a printer, and the like. More specifically, a developer carried on a developing sleeve is divided into a photosensitive drum and a developing sleeve. The present invention relates to a developing roller and a developing device which are transported to a developing area facing each other with a gap and develop a latent electrostatic image on the photosensitive drum to form a toner image. The present invention also relates to a process cartridge and an image forming apparatus having such a developing device.

  In order to carry the developer on the developing sleeve of the developing roller of the image forming apparatus and to reliably convey the developer to the photosensitive drum, the above-described developing sleeve (for example, Patent Documents 1 to 5) is used except in the case of a low-speed machine. Sand blasting is performed on the outer surface of Patent Document 3), grooves are formed on the outer surface, or so-called electromagnetic blasting is performed on the outer surface to randomly collide the wire with a rotating magnetic field. It was.

  The above-described sandblasting and the formation of grooves prevent the developer from slipping on the developing sleeve rotating at a high speed and stagnating, thereby reducing the image density.

  The development sleeve subjected to the sandblasting process described above is composed of any one of aluminum alloy, brass, stainless steel, and conductive resin, but is composed of an aluminum alloy in order to reduce costs and improve processing accuracy. Often. When sandblasting is performed on the outer surface of the developing sleeve made of an aluminum alloy, for example, abrasive grains are sprayed cold on an aluminum tube extruded into a developing sleeve shape at a high temperature to form irregularities on the surface. The surface roughness is formed to about Rz 5.0 to 15 [μm]. In the developing sleeve subjected to sandblasting in this way, even when the developing sleeve is rotated at a high speed, the developer is caught by the unevenness and the occurrence of slip can be prevented.

  However, since the unevenness formed on the outer surface is very fine, the unevenness is gradually scraped by a developer or the like. Therefore, the development sleeve subjected to the sandblasting process described above increases as the number of printed sheets increases. In other words, the above-mentioned unevenness is shaved and flattened due to aging. Therefore, the developing sleeve subjected to the sandblasting process described above has a problem that the amount of developer transport is gradually reduced and the formed image is gradually thinned. Thus, the developing sleeve subjected to sandblasting has a problem of durability. The developing sleeve can be made of high-hardness stainless steel or the surface can be hardened, but this is not desirable because it increases costs.

  Further, the developing sleeve in which the groove is formed on the outer surface is made of any of aluminum alloy, brass, stainless steel, and conductive resin, and the cost is reduced and the processing accuracy is improved as described above. Therefore, it is often composed of an aluminum alloy. When forming the groove on the outer surface of the developing sleeve made of an aluminum alloy, for example, the aluminum tube extruded into a developing sleeve shape at a high temperature is pulled out cold, and the groove is formed by a die. The shape of the groove is generally a square cross-section, V-shape, U-shape, or the like. The depth of the groove is generally about 0.2 [mm] from the outer surface of the developing sleeve, and the number of grooves is generally about 50 for the developing sleeve having an outer diameter of φ18, for example. In the developing sleeve subjected to the groove processing as described above, even when the developing sleeve rotates at a high speed, the developer is caught in the groove and the occurrence of slipping can be prevented.

  Further, the developing sleeve in which the groove is formed on the outer surface is much larger than the unevenness formed by the sand blasting process described above, so that the groove is less likely to be worn and the amount of developer transported with aging changes. There is no decline. That is, the developing sleeve in which the groove is formed on the outer surface has the advantage that the developer can be stably transported with less wear even when used for a long period of time compared to the developing sleeve subjected to sandblasting.

  However, in the developing sleeve in which the groove is formed on the outer surface, the developer conveyed in the groove is larger than the developer conveyed in the portion where the groove is not provided. The occurrence of so-called pitch unevenness is observed. As shown in FIG. 24B, generally, as the groove 202 formed on the outer surface of the developing sleeve 200 is deeper, the developer conveying performance is improved. However, pitch unevenness due to a difference in developing electric field strength depending on the presence or absence of the groove 202 is improved. It tends to occur. On the other hand, if the groove 202 is shallow, pitch unevenness is less likely to occur from the viewpoint of the development electric field strength. However, if the groove 202 is clogged with toner, additives, or magnetic carriers in the developer, the developer conveyance performance is reduced. The degree becomes larger, and pitch unevenness due to insufficient amount of developer drawn up is likely to occur. FIG. 24B is an explanatory diagram showing the developing electric field strength depending on the presence or absence of a groove along the longitudinal direction of the conventional developing sleeve.

  Therefore, as a countermeasure against the above-described problem, in Patent Document 1, by defining the groove depth of the developing sleeve as 0.10 mm or more and 0.15 mm or less, the developer transport function while preventing the occurrence of pitch unevenness. Have been devised to maintain. However, in recent years, in order to obtain high image quality, the use of smaller particle size toners and smaller particle size carriers and the development of image formation technology by proximity development have improved image reproducibility. It is easy. For this reason, even in the image forming apparatus disclosed in Patent Document 1, pitch unevenness may occur.

  When this cause is examined, as shown in FIGS. 25 and 26, in the developing region D where the developing sleeve 200 and the photosensitive drum 201 face each other, the developer is formed on the outer surface of the developing sleeve 200 where the groove 202 is not formed. 203 slipped and the amount of developer 203 decreased, resulting in a decrease in image density. In general, the developer 203 moves in the developing region D where the developing sleeve 200 and the photosensitive drum 201 face each other, but it is necessary to transport a large amount of the developer 203 to the developing region D so as to obtain a sufficient image density. .

  Therefore, normally, the developing sleeve 200 is rotationally driven at a surface speed 1.1 to 2.5 times that of the photosensitive drum 201. When the developer 203 passes through the developing region D at a high speed, friction with the relatively low-speed photosensitive drum 201 becomes a load resistance, and on the outer surface of the developing sleeve 200 at a portion where the groove 202 is not provided, As shown in FIG. 25, the developer 203 slips and the pumping amount is insufficient. For this reason, in the developing region D, the amount of developer on the downstream side is smaller than that on the upstream side in the rotation direction of the developing sleeve 200. On the other hand, as shown in FIG. 26, a sufficient conveying force is obtained while the groove 202 passes through the development area D, so that no slip occurs and the pumping amount is sufficient. That is, in the period of the groove 202 that passes through the development area D, the amount of the developer 203 varies depending on the presence or absence of slippage, and pitch unevenness due to an image density difference occurs.

  In Patent Document 2 described above, a toner having a volume average particle size of 4 μm or more and 8.5 μm or less is used as a developer, and has a plurality of grooves extending in the longitudinal direction on the outer surface of the developing sleeve, and between adjacent grooves. An image forming apparatus has been proposed in which the interval is smaller than the width of the developing area where the developer contacts the photosensitive drum in the surface movement direction of the photosensitive drum. According to this image forming apparatus, at least one groove of the developing sleeve always exists in the developing area, and the groove suppresses the slip of the developer carried on the developing sleeve. Therefore, compared with the case where the groove of the developing sleeve does not exist in the developing region, the variation in the amount of the developer in the developing region can be suppressed to be small. As a result, even when a small particle size toner having a volume average particle size of 8.5 μm or less is used, a high-quality image with good image reproducibility is formed and pitch unevenness due to image density difference is less noticeable.

  In the developing sleeve described in Patent Document 2 described above, it is necessary to narrow the interval between the grooves, and there is a limit to the method of forming the groove with the die by cold drawing of the aluminum tube. Even if the interval is between, the depth deviation of the groove increases in the cutting process or the grinding process as the outer diameter finish, and the image density unevenness due to the groove depth deviation occurs.

  On the other hand, as a groove forming method, in the processing method in which one or a plurality of grooves are simultaneously cut, it is possible to reduce the deviation of the depth of the grooves by narrowing the interval between the grooves, but the number of processing steps is reduced. It will increase and cost will increase.

  Further, in the electromagnetic blast processing shown in Patent Document 3, it is possible to suppress a decrease in the transport amount of the developer due to secular change, but since the linear material is randomly collided with the outer surface of the developing sleeve, it is optimal. It is difficult to set the processing conditions that can extend the life while securing the developer pumping amount, and it is difficult to respond to further increasing pumping amount in order to maintain high image quality in future high-speed machines There was a problem.

  In order to achieve both the suppression of the decrease in the developer conveyance amount due to this type of secular change and the prevention of the occurrence of image unevenness, the applicant of the present invention provides an end mill as a rotary tool that rotates around the axis. The end mill and the developing sleeve are relatively moved in the longitudinal direction of the developing sleeve while the leading end of the developing sleeve is brought into contact with the outer surface of the developing sleeve and the developing sleeve is rotated around the axis. It is proposed that the recesses are regularly formed so that the adjacent ones on the outer surface of the developing sleeve are spaced apart from each other.

  The developing sleeve formed as described above does not have a convex portion that is formed by the conventional sandblasting process, and the concave portion is formed into a larger concave portion. Accordingly, it is possible to suppress a decrease in the transport amount of the developer due to secular change. Further, since the developing sleeve is arranged in a large number at intervals so that the dents formed on the outer surface do not overlap with each other, the developer accumulates in the dent, so that the location where the developer accumulates is uniform on the outer surface. Therefore, it is possible to prevent the image from being uneven.

  However, when a developing sleeve having a recess on the outer surface formed by the end mill is processed, burrs, edges, and the like may be formed at the boundary between the outer surface of the developing sleeve and the inner surface of the recess. For this reason, as the number of printed sheets increases, the boundary portion of the dent is gradually worn by the developer or the like. In this way, when the boundary portion of the dent is gradually worn, the boundary portion of the developing sleeve is worn, and the outer surface of the developing sleeve approaches flat, so that there is a possibility that the amount of developer transport decreases.

  The present invention has been made in view of the above-described background, and can suppress a decrease in developer conveyance amount due to secular change, and can prevent development of an image unevenness, a developing device, and the developing device. It is an object of the present invention to provide a process cartridge and an image forming apparatus including the above.

The developing roller according to claim 1 includes: (a) a magnet roller; and (b) a magnetic carrier that encloses the magnet roller and has a magnetic carrier with toner adsorbed on the outer surface by the magnetic force of the magnet roller. In a developing roller provided with a plurality of developing sleeves that are spaced apart so that the circular or oval dents do not overlap each other,
In the circumferential cross section of the developing sleeve, the boundary between the outer surface and the circular or oval dent in plan view is polished using a fiber sander and formed into a rounded curved surface. It is a feature.

  The developing roller according to claim 2 is the developing roller according to claim 1, wherein a radius of curvature of the boundary portion formed on the rounded curved surface is larger than a volume average particle diameter of the magnetic carrier. It is characterized by being said.

  The developing roller according to claim 3 is the developing roller according to claim 2, wherein a radius of curvature of the boundary portion on the upstream side in the rotation direction of the developing sleeve is equal to the boundary on the downstream side in the rotation direction of the developing sleeve. It is characterized by being larger than the radius of curvature of the part.

  The developing roller according to claim 4 is the developing roller according to any one of claims 1 to 3, wherein the upstream inner surface is located upstream in the rotational direction in a circumferential section of the developing sleeve. A first inner surface formed by an imaginary plane connecting the axial center of the developing sleeve and the bottom of the dent, and a downstream inner surface positioned on the downstream side in the rotational direction in the circumferential cross section of the developing sleeve; It is characterized by being larger than the second angle formed by the virtual plane.

  The developing roller according to claim 5 is the developing roller according to any one of claims 1 to 4, wherein a circumferential cross-sectional shape of the developing sleeve of the recess is formed in an arc shape. In addition, a cross-sectional shape in the longitudinal direction of the developing sleeve having a circular or elliptical recess in plan view is formed in an arc shape.

  A developing roller according to a sixth aspect is the developing roller according to any one of the first to fourth aspects, wherein a cross-sectional shape of the developing sleeve in a circular shape or an elliptical shape in a plan view is a circumferential direction. , And the cross-sectional shape of the recess in the longitudinal direction of the developing sleeve is formed in an arc shape.

  A developing roller according to a seventh aspect is the developing roller according to any one of the first to sixth aspects, wherein the recesses having a circular shape or an elliptical shape in plan view adjacent to each other in the circumferential direction of the developing sleeve. However, it is characterized by being arranged at a position shifted in the longitudinal direction of the developing sleeve.

  A developing roller according to an eighth aspect is the developing roller according to the seventh aspect, characterized in that the circular or elliptical recess in a plan view is spirally arranged on an outer surface of the developing sleeve. .

  The developing roller according to claim 9 is the developing roller according to any one of claims 1 to 8, wherein the circular or elliptical recess in plan view is rotated around an axis. Is formed by cutting the outer surface of the developing sleeve.

  A developing roller according to a tenth aspect is the developing roller according to the ninth aspect, wherein the developing sleeve is arranged such that the circular or elliptical recess in a plan view intersects the axis of the rotary tool. The rotating tool and the developing sleeve are formed by being relatively moved in the longitudinal direction of the developing sleeve while being rotated around the core.

  11. The developing device according to claim 11, wherein the developing roller includes a developing roller having a developing sleeve that adsorbs a magnetic carrier having toner adsorbed on an outer surface thereof. The developing roller according to any one of the above is provided.

  According to a twelfth aspect of the present invention, in the process cartridge having at least a developing device, the developing device includes the developing device according to the eleventh aspect.

  According to a thirteenth aspect of the present invention, there is provided an image forming apparatus having at least a photosensitive drum, a charging device, and a developing device, wherein the developing device includes the developing device according to the eleventh aspect. Yes.

  According to the developing roller of the first aspect, the boundary portion between the outer surface and the dent in the circumferential cross section of the developing sleeve is formed in a rounded curved surface. As described above, since the boundary is rounded in advance, wear of the boundary due to use over time is suppressed, so that a decrease in the transport amount of the developer can be suppressed. In this way, a decrease in image density can be suppressed.

  According to the developing roller of claim 2, the radius of curvature of the boundary portion formed on the rounded curved surface as well as the boundary portion between the outer surface and the recess in the circumferential cross section of the developing sleeve, The volume average particle diameter of the magnetic carrier is larger. Thus, by forming the radius of curvature of the boundary portion larger than the volume average particle diameter of the magnetic carrier, the contact area between the magnetic carrier and the boundary portion is increased, and wear of the boundary portion due to aging is suppressed. As a result, a decrease in image density can be suppressed.

  The developing roller according to claim 3, wherein a radius of curvature of the boundary portion on the upstream side in the rotation direction of the developing sleeve is formed larger than a radius of curvature of the boundary portion on the downstream side in the rotation direction of the developing sleeve. Has been. Since the amount of wear at the boundary due to use over time is greater on the upstream side than on the downstream side in the rotation direction of the developing sleeve, the curvature radius of the boundary portion on the upstream side in the rotation direction of the developing sleeve is determined in advance. By forming it larger than the radius of curvature of the boundary portion on the downstream side in the rotation direction, wear of the boundary portion due to use over time is suppressed, so that a decrease in the transport amount of the developer can be suppressed. In this way, a decrease in image density can be suppressed.

  The developing roller according to claim 4, wherein, in the recess in the circumferential section of the developing sleeve, an upstream inner surface located on the upstream side in the rotational direction in the circumferential section of the developing sleeve, and the developing sleeve A first inner surface formed by an imaginary plane connecting the axis of the dent and the bottom of the dent, a downstream inner surface located on the downstream side in the rotational direction in the circumferential section of the developing sleeve, and the imaginary plane. It is formed larger than the second angle formed. Since the amount of wear at the boundary due to use over time is greater on the upstream side than on the downstream side in the rotation direction of the developing sleeve, the first angle is previously set to be larger than the second angle (that is, outside the developing sleeve). Since the surface and the upstream inner surface are formed to have a gentler slope), it is possible to suppress the decrease in the transport amount of the developer by suppressing the wear of the boundary portion due to use over time. In this way, a decrease in image density can be suppressed.

  According to the developing roller of the fifth aspect, since the cross-sectional shapes in both the longitudinal direction and the circumferential direction of the recessed developing sleeve are formed in an arc shape, the amount of developer that can be accommodated in the recessed portion is increased. A sufficient amount of developer can be transported.

  According to the developing roller of the sixth aspect, since the sectional shape in the longitudinal direction of the concave developing sleeve is formed in an arc shape, the amount of developer that can be accommodated in the concave can be increased. An appropriate amount of developer can be conveyed.

  According to the developing roller of the seventh aspect, since the dents adjacent to each other in the circumferential direction are displaced in the longitudinal direction of the developing sleeve, there are portions or dents where no dent is formed on the outer surface of the developing sleeve. It can prevent that many places etc. arise. Accordingly, unevenness occurs in the developer adsorbed on the outer surface of the developing sleeve, that is, the developer can be adsorbed uniformly on the outer surface of the developing sleeve. Therefore, it is possible to prevent image unevenness.

  According to the developing roller of claim 8, since the recess is spirally arranged on the outer surface of the developing sleeve, unevenness occurs in the developer adsorbed on the outer surface of the developing sleeve, that is, the outer surface of the developing sleeve. Can uniformly adsorb the developer. Therefore, it is possible to prevent image unevenness.

  According to the developing roller of the ninth aspect, since the dent is formed on the outer surface of the developing sleeve by the rotating tool, the dent can be easily and reliably formed on the outer surface of the developing sleeve. Therefore, it is possible to prevent image unevenness.

  According to the developing roller of the tenth aspect, since the dent is formed while rotating around the axis of the developing sleeve and moving the rotary tool, the dent can be reliably formed on the outer surface of the developing sleeve. In addition, the recesses can be formed regularly. Therefore, it is possible to prevent image unevenness.

  Since the developing device according to the eleventh aspect includes the developing roller described above, it is possible to suppress a decrease in the transport amount of the developer due to secular change and to prevent occurrence of image unevenness.

  Since the process cartridge according to the twelfth aspect includes the developing device according to the eleventh aspect, it is possible to suppress a decrease in the developer conveyance amount due to secular change and to prevent occurrence of image unevenness.

  Since the image forming apparatus according to the thirteenth aspect includes the developing apparatus according to the eleventh aspect, it is possible to suppress a decrease in the transport amount of the developer due to secular change and to prevent occurrence of image unevenness.

1 is an explanatory diagram viewed from the front of a configuration of an image forming apparatus including a developing sleeve according to a first embodiment of the present invention. FIG. 2 is a sectional view of a process cartridge of the image forming apparatus shown in FIG. 1. It is sectional drawing which follows the III-III line | wire in FIG. FIG. 2 is a perspective view showing a developing sleeve of the image forming apparatus shown in FIG. 1. FIG. 5 is an explanatory view schematically showing the outer surface of the developing sleeve shown in FIG. 4 in a developed state. (A) is explanatory drawing which expands and shows typically a part of outer surface of the image development sleeve shown by FIG. 5, (b) follows the VIB-VIB line | wire in FIG. 6 (a). It is sectional drawing, (c) is sectional drawing which follows the VIC-VIC line | wire in Fig.6 (a). FIG. 5 is an explanatory view showing an enlarged part of the outer surface of the developing sleeve shown in FIG. 4. It is sectional drawing which expands and shows a part of FIG.6 (b). (A) is a side view showing a schematic configuration of a surface treatment apparatus for cutting and polishing the outer surface of the developing sleeve shown in FIG. 4, and (b) is a VIIIB in FIG. 9 (a). It is sectional drawing which follows the -VIIIB line, (c) is an enlarged side view which shows the end mill shown by FIG.9 (b). FIG. 10 is an explanatory diagram showing a state where a fiber sander as an abrasive is attached to the surface treatment apparatus shown in FIG. 9 to polish the developing sleeve shown in FIG. 4. FIG. 5 is an explanatory view schematically showing an enlarged part of the outer surface of the developing sleeve shown in FIG. 4. FIG. 5 is an explanatory view showing, in an enlarged manner, a state in which a magnetic carrier is adsorbed on the outer surface of the developing sleeve shown in FIG. 4. It is explanatory drawing which expands and shows typically a part of outer surface of the image development sleeve shown by 2nd Embodiment. It is a side view which expands and shows the end mill for forming the dent provided in the outer surface of the developing sleeve shown in FIG. (A) is explanatory drawing which expands and shows typically a part of outer surface of the modification of the image development sleeve shown by Fig.6 (a), (b) is FIG.15 (a) in FIG. It is sectional drawing which follows the IXB-IXB line, (c) is sectional drawing which follows the IXC-IXC line | wire in Fig.15 (a). (A) is an enlarged side view showing an end mill for forming a recess provided on the outer surface of the developing sleeve shown in FIG. 15, and (b) is shown in FIG. 16 (a). It is a front view of the front-end | tip part of an end mill. FIG. 7 is a cross-sectional view showing a modified example of a dent formed on the outer surface of the developing sleeve shown in FIG. FIG. 10 is a cross-sectional view showing another modification of the dent formed on the outer surface of the developing sleeve shown in FIG. It is explanatory drawing which shows the example by which the dent is arrange | positioned regularly. It is explanatory drawing which shows the other example by which the dent is arrange | positioned regularly. It is explanatory drawing which shows typically the planar shape of a dent. FIG. 3 is an explanatory view showing, in an enlarged manner, a state in which a magnetic carrier is adsorbed on the outer surface of the developing sleeve shown in Comparative Product 1. 6 is a graph showing the relationship between the radius of curvature of the boundary between the outer surface of the developing sleeve and the recess and the number of sheets fed by the image forming apparatus. (A) is explanatory drawing which shows the image development electric field strength along the longitudinal direction of the image development sleeve shown by FIG. (B) is explanatory drawing which shows the image development electric field strength by the presence or absence of the groove | channel along the longitudinal direction of the conventional image development sleeve. It is explanatory drawing which shows the state which the conventional developing sleeve draws up a developing agent. It is explanatory drawing which shows the other state in which the conventional developing sleeve draws up a developing agent.

  A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory diagram viewed from the front of the configuration of an image forming apparatus including a developing sleeve according to the first embodiment of the present invention. 2 is a cross-sectional view of the process cartridge of the image forming apparatus shown in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a perspective view showing a developing sleeve of the image forming apparatus shown in FIG. FIG. 5 is an explanatory view schematically showing the outer surface of the developing sleeve shown in FIG. 6A is an explanatory view schematically showing a part of the outer surface of the developing sleeve shown in FIG. 5, and FIG. 6B is a VIB-VIB line in FIG. 6A. (C) is sectional drawing which follows the VIC-VIC line | wire in Fig.6 (a). FIG. 7 is an explanatory view showing a part of the outer surface of the developing sleeve shown in FIG. 4 in an enlarged manner. FIG. 8 is an enlarged cross-sectional view of a part of FIG. FIG. 9A is a side view showing a schematic configuration of a surface treatment apparatus for cutting and polishing the outer surface of the developing sleeve shown in FIG. 4, and FIG. 9B is a side view of FIG. It is sectional drawing which follows the VIIIB-VIIIB line | wire, (c) is a side view which expands and shows the end mill shown by FIG.9 (b). FIG. 10 is an explanatory view showing a state where a fiber sander as an abrasive is attached to the surface treatment apparatus shown in FIG. 9 to polish the developing sleeve shown in FIG. FIG. 11 is an explanatory view schematically showing a part of the outer surface of the developing sleeve shown in FIG. FIG. 12 is an explanatory view showing, in an enlarged manner, a state in which the magnetic carrier is adsorbed on 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). ) To form. 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 feed unit 103, a registration roller pair 110, a transfer unit 104, a fixing unit 105, and a plurality of laser writing units 122Y, 122M, and 122C. , 122K and a plurality of process cartridges 106Y, 106M, 106C, 106K.

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

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

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

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

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

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

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

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

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

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

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

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

  The storage tank 117 stores the developer 126 in both the first space 120 and the second space 121. The developer 126 includes toner and a magnetic carrier (also referred to as magnetic powder) 135. The toner is appropriately supplied to one end portion of the first space 120 on the side away from the developing roller 115 in the first space 120 and the second space 121. The toner is spherical fine particles produced by an emulsion polymerization method or a suspension polymerization method. The toner may be obtained by pulverizing a lump composed of a synthetic resin in which various dyes or pigments are mixed and dispersed. The volume average particle diameter of the toner is 3 μm or more and 7 μm or less. The toner may be formed by pulverization or the like.

  The magnetic carrier 135 is accommodated in both the first space 120 and the second space 121. The volume average particle diameter of the magnetic carrier 135 is 20 μm or more and 50 μm or less. By using the toner having a small particle diameter or the magnetic carrier 135 as described above, the image reproducibility is improved and a high quality image can be obtained.

  The stirring screw 118 is accommodated in each of the first space 120 and the second space 121. The longitudinal direction of the stirring screw 118 is parallel to the longitudinal directions of the storage tank 117, the developing roller 115, and the photosensitive drum 108. The agitating screw 118 is provided so as to be rotatable around an axis, and rotates around the axis to agitate the toner and the magnetic carrier 135 and convey the developer 126 along the axis.

  In the illustrated example, the agitation screw 118 in the first space 120 conveys the developer 126 from one end to the other end. The agitation screw 118 in the second space 121 conveys the developer 126 from the other end toward the one end.

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

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

  The developing roller 115 is formed in a cylindrical shape, and is provided between the second space 121 and the photosensitive drum 108 and in the vicinity of the opening 125a described above. The developing roller 115 is parallel to both the photosensitive drum 108 and the storage tank 117. The developing roller 115 is disposed at a distance from the photosensitive drum 108. A space between the developing roller 115 and the photosensitive drum 108 forms a developing region 131 in which the toner of the developer 126 is attracted to the photosensitive drum 108 and the electrostatic latent image is developed to obtain a toner image. In the developing area 131, the developing roller 115 and the photosensitive drum 108 face each other.

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

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

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

  One fixed magnetic pole is opposed to the agitating screw 118 described above. The one fixed magnetic pole serves as a pumping magnetic pole, generates a magnetic force on the outer surface of the developing sleeve 132, that is, the developing roller 115, and causes the developer 126 in the second space 121 of the storage tank 117 to flow to the developing sleeve 132. Adsorb to the outer surface.

  The other fixed magnetic pole is opposed to the photosensitive drum 108 described above. The fixed magnetic pole forms a developing magnetic pole, and generates a magnetic force on the outer surface of the developing sleeve 132, that is, the developing roller 115, thereby forming a magnetic field between the developing sleeve 132 and the photosensitive drum 108. The fixed magnetic pole forms a magnetic brush by the magnetic field, so that the toner of the developer 126 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 126 before development toward the photosensitive drum 108, and develops the developed developer 126. Is conveyed from the photosensitive drum 108 into the storage tank 117.

  When the developer 126 adsorbs the developer 126 to the outer surface of the developing sleeve 132, a plurality of the magnetic carriers 135 of the developer 126 overlap each other along the lines of magnetic force generated by the fixed magnetic pole. To stand up. In this manner, a state in which a plurality of magnetic carriers 135 are erected on the outer surface of the developing sleeve 132 along the lines of magnetic force is referred to as the magnetic carrier 135 rising on the outer surface of the developing sleeve 132. Then, the above-described toner is adsorbed to the magnetic carrier 135 that is raised. That is, the developing sleeve 132 attracts the developer 126 to the outer surface by the magnetic force of the magnet roller 133.

  As shown in FIG. 4, the developing sleeve 132 is formed in a cylindrical shape. The developing sleeve 132 includes (accommodates) the magnet roller 133 and is provided to be rotatable around the shaft core 132a. 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 surface processing on the outer surface by the surface treatment apparatus 1 (shown in FIG. 9A). The developing sleeve 132 according to the first embodiment of the present invention corresponds to the product 1 of the present invention described later.

  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 desirably about 14 mm to 30 mm. The length of the developing sleeve 132 in the axial direction is preferably about 300 mm to 350 mm.

  Further, as shown in FIGS. 4, 5, 6 (a), and 7, the outer surface of the developing sleeve 132 is provided with a number of recesses 139 that are elliptical 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 invention, the fact that the intervals between the recesses 139 adjacent to each other in the circumferential direction and the longitudinal direction of the developing sleeve 132 are constant is referred to as the regular arrangement of the recesses 139. That is, the interval between the recesses 139 adjacent to each other in the circumferential direction and the longitudinal direction of the developing sleeve 132 is constant.

  As an example in which the recesses 139 are regularly arranged, for example, as shown in FIG. 5, the recesses 139 may be arranged at the same pitch (same interval) in the circumferential direction on a row of spirals. The same applies to the case where the recesses 139 are arranged on two or more spirals.

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

  Further, as shown in FIGS. 5, 6 (a) and 7, a plurality of the recesses 139 are arranged along the longitudinal direction of the developing sleeve 132 and are adjacent to each other in the circumferential direction of the developing sleeve 132. The matching ones are arranged so as to be displaced by about half the length of the recess 139. Further, since the recess 139 is formed on the outer surface of the developing sleeve 132 by the surface treatment apparatus 1 shown in FIG. 9A, the recess 139 is formed on the outer surface of the developing sleeve 132 on a spiral indicated by a one-dot chain line in FIG. They are arranged side by side.

  Further, as shown in FIGS. 6B and 6C and FIGS. 11 and 12, the recess 139 intersects the axis 132a of the developing sleeve 132 along the circumferential direction of the developing sleeve 132 (in the illustrated example, orthogonal). In the cross section, an upstream inner surface 140 that is continuous with the outer surface of the developing sleeve 132 and is located upstream of the developing sleeve 132 in the rotation direction S1 and a downstream inner surface 141 that is continuous with the upstream inner surface 140 are provided. . A bottom 139 a of the recess 139 is located between the upstream inner surface 140 and the downstream inner surface 141. The bottom 139a is the bottom of the recess 139. A boundary portion 143 between the outer surface of the developing sleeve 132 and the upstream inner surface 140 connected to the outer surface of the developing sleeve 132 is formed in a rounded curved surface, and the downstream side connected to the upstream inner surface 140. A boundary portion 144 between the inner surface 141 and the outer surface of the developing sleeve 132 connected to the downstream inner surface 141 is formed in a rounded curved surface. In this way, the cross section that intersects (is orthogonal to the illustrated example) the core 132a of the developing sleeve 132 along the circumferential direction of the developing sleeve 132 is formed in a curved surface with rounded boundaries 143 and 144. In addition, the upstream inner surface 140 and the downstream inner surface 141 connected to the upstream inner surface 140 are formed in an arc shape. That is, the circumferential cross-sectional shape of the developing sleeve 132 is formed in an arc shape. In FIG. 12, the toner adsorbed on the magnetic carrier 135 is omitted.

  The cross-sectional shape in the longitudinal direction of the developing sleeve 132 of the recess 139 is also formed in an arc shape. That is, the developing sleeve 132 is formed in a circular arc shape in both the circumferential direction and the longitudinal direction. 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. 9A, the longitudinal direction thereof is slightly curved in an arcuate shape as shown in FIG. In the present invention, if the longitudinal direction of the dent 139 is longer than the length in the width direction and the outer edge of the dent 139 is formed as a curve, the general term is used regardless of whether the longitudinal direction is a straight line or slightly curved. To have an elliptical shape.

The length (major axis) in the longitudinal direction of the recess 139 is 0.3 mm or more and 2.3 mm or less, and the width (minor axis) in the width direction is 0.10 mm or more and 0.7 mm or less. And the depth is 0.03 mm or more and 0.15 mm or less. Further, about 50 to 250 recesses 139 are provided per 100 mm ² of the outer surface of the developing sleeve 132. That is, the total capacity of the plurality of (many) dents 139 is 0.5 mm ³ or more and 7.0 mm ³ or less per 100 mm ² of the outer surface of the developing sleeve 132. Furthermore, 1.0 or more and 3.0 or less recesses 139 are provided in the circumferential direction of the photosensitive drum 108 that rotates together with the developing sleeve 132. 5, 6 </ b> A, and 7, the horizontal direction in the drawing is the longitudinal direction of the developing sleeve 132.

  The curvature radii R1 and R2 of the boundary portion 143 on the upstream side in the rotation direction S1 of the developing sleeve 132 and the boundary portion 144 on the downstream side in the rotation direction S1 of the developing sleeve 132 are formed to be 0.10 mm. It is formed larger than the volume average particle diameter. Thus, the radii of curvature R1 and R2 of the boundary portions 143 and 144 between the outer surface and the recess 139 in the circumferential cross section of the developing sleeve 132 are formed larger than the volume average particle diameter of the magnetic carrier 135.

  Further, an upstream inner surface 140 located on the upstream side in the rotation direction S1 of the developing sleeve 132, in a cross section intersecting (orthogonal in the illustrated example) with respect to the axial core 132a of the developing sleeve 132 along the circumferential direction of the developing sleeve 132; A first angle θ1 formed by a virtual surface 145 connecting the shaft 132a of the developing sleeve 132 and the bottom 139a of the recess 139, and a downstream inner surface 141 located downstream of the rotation direction S1 of the developing sleeve 132; The second angle θ2 formed by the virtual surface 145 is 45 degrees. That is, in the cross section intersecting (orthogonal in the illustrated example) with respect to the axial core 132a of the developing sleeve 132 along the circumferential direction of the developing sleeve 132, the outer surface of the developing sleeve 132 and the upstream side in the rotation direction S1 of the developing sleeve 132 The third angle θ3 formed by the upstream inner surface 140, the downstream inner surface 141 connected to the upstream inner surface 140 and downstream of the developing sleeve 132 in the rotation direction S1, and the outer side of the developing sleeve 132 connected to the downstream inner surface 141. The fourth angle θ4 formed by the surface is formed at 45 degrees. The virtual surface 145 described above is orthogonal to the outer surface of the developing sleeve 132.

  Further, a third surface formed by the outer surface of the developing sleeve 132 and the upstream inner surface 140 in a cross section that intersects (is orthogonal to the illustrated example) the axial core 132a of the developing sleeve 132 along the circumferential direction of the developing sleeve 132. The angle θ3 and the fourth angle θ4 (shown in FIG. 8) formed by the downstream inner surface 141 and the outer surface of the developing sleeve 132 are for avoiding the development density difference generated by the influence of the developing magnetic pole described above. It is preferable that it is 60 degrees or less.

  In general, the deeper the recess 139 is, the more the developer 126 is transported. However, periodic pitch unevenness is likely to occur as in the case of a conventional developing sleeve provided with a groove on the outer surface. On the other hand, as the dent 139 is shallower, pitch unevenness is less likely to occur, but the transport performance of the developer 126 is degraded. In particular, in recent years, the image reproducibility has been improved due to the progress of image forming technology for small-diameter toner and magnetic carrier 135 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 attached to the case 125 described above with a space from the outer surface of the developing sleeve 132. The doctor blade 116 scrapes the developer 126 on the outer surface of the developing sleeve 132 exceeding the desired thickness into the storage tank 117, and the developer 126 on the outer surface of the developing sleeve 132 conveyed to the developing region 131. To the desired thickness.

  In the developing device 113 configured as described above, the developer and the magnetic carrier 135 are sufficiently stirred by the developer supply unit 114, and the stirred developer 126 is adsorbed to the outer surface of the developing sleeve 132 by the fixed magnetic pole. Then, the developing device 113 conveys the developer 126 adsorbed by the plurality of fixed magnetic poles toward the developing region 131 as the developing sleeve 132 rotates. The developing device 113 adsorbs the developer 126 having a desired thickness by the doctor blade 116 to the photosensitive drum 108. In this way, the developing device 113 carries the developer 126 on the developing roller 115, conveys it to the developing area 131, and develops the electrostatic latent image on the photosensitive drum 108 to form a toner image.

  Then, the developing device 113 causes the developed developer 126 to be released toward the storage tank 117. Further, the developed developer 126 stored in the storage tank 117 is sufficiently stirred again with the other developer 126 in the second space 121, and the electrostatic latent image on the photosensitive drum 108 is recovered. Used for development. In the developing device 113, when a toner concentration sensor (to be described later) detects that the concentration of toner supplied to the photosensitive drum 108 by the developer supply unit 114 has decreased, for example, a toner supply control device (not shown) is activated. The toner is supplied from the storage tank 117.

  The image forming apparatus 101 having the above-described configuration forms an image on the recording paper 107 as described below. First, the image forming apparatus 101 rotates the photosensitive drum 108 and uniformly charges the outer surface of the photosensitive drum 108 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 126 adsorbed on the outer surface of the developing sleeve 132 of the developing device 113 is exposed to light. The electrostatic latent image is developed by being attracted to the outer surface of the photosensitive drum 108, and a toner image is formed on the outer surface of the photosensitive drum 108.

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

  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 initialized by a static elimination lamp (not shown) and used for the next image forming process.

  In the image forming apparatus 101 described above, process control is performed in order to suppress image quality fluctuations due to environmental fluctuations and temporal fluctuations. Specifically, first, the developing ability in the developing device 113 is detected. For example, an image of a certain toner pattern is formed on the photosensitive drum 108 under a condition where the developing bias voltage is constant, the image density is detected by an optical sensor (not shown), and the developing ability is grasped from the density change. 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) operates the toner supply control device to increase the toner density and accommodates it. Toner is supplied from the tank 227. Here, the toner density is detected by a toner density sensor (not shown). It should be noted that the image density of the toner pattern formed on the photosensitive drum 108 may vary somewhat due to the influence of the image density cycle unevenness caused by the developing sleeve 132.

  The above-described developing sleeve 132 has a recess 139 formed on the outer surface by the surface treatment apparatus 1 shown in FIG.

  As shown in FIG. 9A, 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 portion of the fixed column 9. 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 of the rotary chuck 10 in the axial direction is fixed as appropriate.

  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. The slide holding portion 8 is brought close to the fixed holding portion 7, the tip portions of the chuck pins 11 and 15 enter the end portion of the developing sleeve 132, and the developing sleeve 132 is sandwiched between the chuck pins 11 and 15. In the state, 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 the longitudinal direction thereof is arranged in parallel with the longitudinal direction of the base 3 and the axial center 132a of the developing sleeve 132 sandwiched between the chuck pins 11 and 15, that is, the chuck pins 11 and 15. Has been. 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 along the axial center 132 a of the developing sleeve 132 that sandwiches the slider 18 described above in the longitudinal direction of the base 3 and is sandwiched between the chuck pins 11 and 15, that is, the chuck pins 11 and 15. And slide it.

  The tool 6 includes a tool body 19, a tool rotating motor 20 as a tool rotating portion, an end mill 21 as a rotating tool that forms a large number of recesses 139 by cutting the outer surface of the developing sleeve 132, and a developing sleeve And a fiber sander 26 as an abrasive that polishes the boundary portions 143 and 144 of the dent 139 of 132. 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. 9B, 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 where its axis is parallel to the surface of the base 3 and intersects with the axis 132a of the developing sleeve 132 sandwiched between the chuck pins 11 and 15 (orthogonal in the illustrated example). Is arranged in.

  The surface treatment apparatus 1 forms a recess 139 by cutting the outer surface of the developing sleeve 132. At this time, an end mill 21 is attached to the tip of the output shaft 22 of the above-described tool rotation motor 20. After the recess 139 is formed in the developing sleeve 132 by the end mill 21, the end mill 21 is removed from the tool rotating 20 described above, and the developing sleeve 132 is attached to the tip of the output shaft 22 of the tool rotating motor 20 described above. A fiber sander 26 for polishing the boundary portions 143 and 144 between the outer surface and the recess 139 is attached.

  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 in which its axis is parallel to the surface of the base 3 and intersects the axis 132a of the developing sleeve 132 sandwiched between the chuck pins 11 and 15 (orthogonal in the illustrated example). Has been. 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. 9C, 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 blades 24 are provided at intervals in the circumferential direction of the distal end portion of the main body portion 23 near the developing sleeve 132. As shown in FIG. 9C, the cutting blade 24 is provided so as to protrude from the outer edge 25 of the distal end portion of the main body portion 23 in the circumferential direction of the main body portion 23, that is, the end mill 21, and extends on the spiral. . When forming the developing sleeve 132 shown in the above-described first embodiment in which the circumferential cross-sectional shape is formed in an arc shape, the cross-sectional shape of the outer edge 25 of the distal end portion of the cutting blade 24 of the end mill 21. Is formed in an arc shape.

  The fiber sander 26 is formed of a synthetic fiber made of a nylon synthetic resin such as PA (PolyAmide). As shown in FIG. 10, the fiber sander 26 is formed in a cylindrical 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 fiber sander 26 is in a state where its axis is parallel to the surface of the base 3 and intersects with the axis 132a of the developing sleeve 132 sandwiched between the chuck pins 11 and 15 (orthogonal in the illustrated example). Has been placed. The fiber sander 26 is disposed so as to protrude from the upper end portion of the tool body 19 toward the developing sleeve 132 sandwiched between the chuck pins 11 and 15.

  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. Then, after the end mill 21 attached to the tip of the output shaft 22 of the tool rotation motor 20 is replaced with the fiber sander 26, the tool rotation motor 20 moves the fiber sander 26 around its axis. , The boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139 are polished. Thus, roundness is formed at the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139 formed on the outer surface of the developing sleeve 132.

  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 132 a with the motor 2 as a rotation driving unit, and the end mill with the tool rotating motor 20. The tool 6 is moved along the axis 132a (longitudinal direction) of the developing sleeve 132 by the moving actuator while rotating 21 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 139 of the recess 139 in the longitudinal direction of the developing sleeve 132 is determined by the radius of curvature of the outer edge 25 of the cutting blade 24, and the depth of the recess 139 is determined by the amount of cutting of the cutting blade 24. Thus, the interval in the longitudinal direction of the developing sleeve 132 of the recess 139 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. , M, and the rotation speed of the end mill 21 is N2, the control device satisfies the following expression 1 so that the motor 2 as the rotation drive unit, the moving actuator of the tool moving unit 5, and the tool of the tool 6 The motor 20 for rotation is controlled.

  N2 = N1 × [m / [(n / 2) −0.5]] Equation 1

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

  Further, when polishing the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139, the control device rotates the developing sleeve 132 around its axis by the motor 2 as a rotation driving unit. The tool 6 is moved along the axis 132 a (longitudinal direction) of the developing sleeve 132 by the moving actuator while the fiber sander 26 is rotated around the axis by the tool rotating motor 20. Then, the control device intermittently polishes the boundary portions 143 and 144 between the outer surface of the image sleeve 132 and the recess 139 as the fiber sander 26 rotates. Thus, roundness is formed at the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139 formed on the outer surface of the developing sleeve 132.

  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 and polishing the outer surface of the developing sleeve 132 using the surface treatment apparatus 1 having the above-described configuration will be described below.

  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 arranged so as to intersect with the end mill 21 (orthogonal in the illustrated example) is rotated around its axis 132a, The end mill 21 and the developing sleeve 132 are relatively moved in the longitudinal direction of the developing sleeve 132 to form a recess 139.

  The end mill 21 is positioned at the processing end position of the developing sleeve 132, that is, the other end of the developing sleeve 132, and the above-described cutting of the outer surface of the developing sleeve 132 ends. Then, the end mill 21 is removed from the tool rotation motor 20, and the fiber sander 26 is attached to the tip of the output shaft 22 of the tool rotation motor 20. Thereafter, the control device positions the fiber sander 26 of the tool 6 at the processing start position, that is, one end of the developing sleeve 132, and then holds the developing sleeve 132 after the recess 139 is formed in the holding portion 4. At this time, the developing sleeve 132 and the chuck pins 11 and 15 are coaxial.

  When a work start command is input from the input device, the control device drives the motor 2 as a rotation driving unit, the moving actuator of the tool moving unit 5, and the tool rotating motor 20 of the tool 6. Then, the fiber sander 26 rotating about the axis intermittently polishes the boundary portions 143 and 144 of the recess 139 of the developing sleeve 132, so that the boundary portion 143 between the outer surface of the developing sleeve 132 and the recess 139, A roundness is formed at 144. That is, roundness of the boundary portions 143 and 144 of the recess 139 is polished at the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139 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 driven simultaneously, the development is performed by the fiber sander 26 in which the recess 139 is rotated around the axis. The developing sleeve 132, which has been polished at the boundary portions 143 and 144 of the recess 139 of the sleeve 132 and is crossed (orthogonal in the illustrated example) with respect to the fiber sander 26, is rotated around its axis 132a, The fiber sander 26 and the developing sleeve 132 are relatively moved in the longitudinal direction of the developing sleeve 132, and roundness is formed at the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139.

  As described above, the radii of curvature R1 and R2 of the boundary portions 143 and 144 formed on the rounded curved surface are formed to be 0.10 mm. In this way, in order to form the radius of curvature R1 of the boundary portion 143 and the radius of curvature R2 of the boundary portion 144 in the same dimension, the developing sleeve 132 is rotated in both the same direction and the opposite direction to the rotational direction S1. Thus, the radius of curvature R1 of the boundary portion 143 and the radius of curvature R2 of the boundary portion 144 can be formed to the same size.

  When the fiber sander 26 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 polishing 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 a large number of recesses 139 are formed on the outer surface from between the chuck pins 11, 15 of the holding portions 7, 8, and the boundary portion between the outer surface and the recess 139 The developing sleeve 132 having the rounded corners 143 and 144 is taken out, and a new developing sleeve 132 is held by the holding unit 4. Thus, the above-described developing sleeve 132 (shown in FIG. 4) is obtained.

  According to the first embodiment described above, the boundary portions 143 and 144 between the outer surface and the recess 139 in the circumferential cross section of the developing sleeve 132 are formed in rounded curved surfaces. As described above, since the boundary portions 143 and 144 are rounded in advance, the wear of the boundary portions 143 and 144 due to aged use is suppressed, so that a decrease in the transport amount of the developer can be suppressed. In this way, a decrease in image density can be suppressed.

  Further, the radii of curvature R1 and R2 of the boundary portions 143 and 144 between the outer surface and the recess 139 in the circumferential cross section of the developing sleeve 132 are formed larger than the volume average particle diameter of the magnetic carrier 135. Thus, by forming the curvature radii R1 and R2 of the boundary portions 143 and 144 larger than the volume average particle diameter of the magnetic carrier 135, the contact area between the magnetic carrier 135 and the boundary portions 143 and 144 is increased. By suppressing the wear of the boundary portions 143 and 144 due to aged use, it is possible to suppress a decrease in the developer conveyance amount. In this way, a decrease in image density can be suppressed.

  Further, the recess 139 is formed such that the cross-sectional shape of the developing sleeve 132 in the longitudinal direction is an arc shape. Further, the circumferential cross-sectional shape of the developing sleeve 132 of the recess 139 is also formed in an arc shape. That is, the developing sleeve 132 is formed in a circular arc shape in both the circumferential direction and the longitudinal direction. As described above, since the circumferential cross-sectional shape of the developing sleeve 132 is formed in an arc shape, the amount of the developer 126 that can be accommodated in the recess 139 can be increased. Therefore, the developer 132 can convey a sufficient amount of the developer 126.

  In the developing sleeve 132 in which both the circumferential and longitudinal cross-sectional shapes are formed in an arc shape, from the viewpoint of developing electric field strength, the developing sleeve 132 and the photosensitive drum 108 are more separated as the depth of the recess 139 increases. The development electrolysis strength in the opposite development area is weakened. In this way, it is considered that pitch unevenness due to a difference in development electrolytic strength or the like is likely to occur. For example, as shown in FIG. 24B, in the developing sleeve 200 in which a conventional groove 202 having a square cross section is formed on the outer surface, the depth of the groove 202 in the longitudinal direction is constant. When the developing sleeve 200 is rotated, a portion where the development electrolysis strength is strong (that is, the groove upper portion shown in FIG. 24B) and a portion where the development electrolysis strength is weak (that is, the groove bottom portion shown in FIG. It occurs alternately in the circumferential direction. That is, pitch unevenness due to a difference in developing electric field strength is likely to occur. However, both the circumferential direction and the longitudinal direction of the developing sleeve 132 are formed in an arc shape, and the depth of the recess 139 with respect to the outer surface of the developing sleeve 139 is in both the circumferential direction and the longitudinal direction. Since it changes gently, as shown in FIG. 24A, the developing electric field strength also changes gently in both the circumferential direction and the longitudinal direction of the developing sleeve 132. In this way, pitch unevenness does not occur, and in particular, the color image forming apparatus 101 often outputs an image with a high image area ratio, so that a more stable image density can be obtained and a high-quality color image can be obtained. it can.

  Moreover, since there is no convex part formed by the conventional sandblasting process on the outer surface and the concave part 139 is formed into a larger concave part 139, the concave part 139 is less likely to be worn even with aging. A decrease in the transport amount of the developer 126 due to the change can be suppressed.

  In addition, since the recesses 139 are regularly arranged, it is easy to set processing conditions that can achieve a long life while securing an optimal amount of developer 126 to be pumped, and reliably under the set conditions. In addition, the recess 139 can be formed and the workability is excellent.

Further, a plurality of recesses 139 that are long in the longitudinal direction are regularly arranged on the outer surface of the developing sleeve 132, and the total volume of the recesses 139 is 0.5 mm ³ or more per 100 mm ² of the outer surface area of the developing sleeve 132. Therefore, a sufficient conveying force of the developer 126 can be obtained.

  Further, the recesses 139 are regularly arranged with the same shape and the same size to prevent image unevenness due to uneven transportability, and the recesses 139 of the developing sleeve 132 are formed per 1 mm in the circumferential direction of the outer surface of the photosensitive drum 108. Since 1.0 or more exists, a plurality of dents 139 can always be present in the development region 131, so that image unevenness due to slip of the developer 126 can be prevented.

  Since the longitudinal direction of the recess 139 is arranged in parallel with the longitudinal direction of the developing sleeve 132, the developer 126 to be pumped up is juxtaposed along the longitudinal direction of the developing sleeve 132. Even if the developer 126 is rotated, it becomes difficult for the developer 126 drawn up to fall off from the outer surface of the developing sleeve 132. Therefore, the recess 139 having an elliptical shape in plan view has the same effect as the groove conventionally used. The pumping amount of the developer 126 can be ensured.

  Since the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 are displaced in the longitudinal direction of the developing sleeve 132, many portions and recesses 139 are formed on the outer surface of the developing sleeve 132 where the recess 139 is not formed. It is possible to prevent the occurrence of a spot or the like. Accordingly, unevenness occurs in the developer 126 adsorbed on the outer surface of the developing sleeve 132, that is, the developer 126 can be adsorbed uniformly on the outer surface of the developing sleeve 132. Therefore, it is possible to prevent image unevenness.

  Since the recess 139 is spirally arranged on the outer surface of the developing sleeve 132, the developer 126 adsorbed on the outer surface of the developing sleeve 132 is uneven, that is, the developer 126 is uniformly formed on the outer surface of the developing sleeve 132. Can be adsorbed. Therefore, it is possible to prevent image unevenness.

  Since the end mill 21 forms the recess 139 on the outer surface of the developing sleeve 132, the recess 139 can be reliably and regularly formed on the outer surface of the developing sleeve 132. Therefore, it is possible to prevent image unevenness.

  Since the dent 139 is formed while rotating the developing sleeve 132 around the axis 132a and moving the end mill 21, the dent 139 can be reliably and regularly formed on the outer surface of the developing sleeve 132. Therefore, it is possible to prevent image unevenness.

  Since the developing device 113, the process cartridges 106Y, 106M, 106C, and 106K and the image forming apparatus 101 include the above-described developing roller 115, it is possible to suppress a decrease in the transport amount of the developer 126 due to secular change, and image unevenness. Can be prevented.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the developing sleeve 132 ′ shown in the second embodiment, the same parts as those of the developing sleeve 132 shown in the first embodiment are denoted by the same reference numerals.

  The curvature radii R1 and R2 of the boundary portion 143 on the upstream side in the rotational direction S1 of the developing sleeve 132 ′ and the boundary portion 144 on the downstream side in the rotational direction S1 of the developing sleeve 132 ′ are formed to be 0.10 mm, and are magnetic. It is formed larger than the volume average particle diameter of the carrier 135. Thus, the radii of curvature R1 and R2 of the boundary portions 143 and 144 between the outer surface and the recess 139 in the circumferential section of the developing sleeve 132 'are formed larger than the volume average particle diameter of the magnetic carrier 135.

  Further, the upstream inner surface located on the upstream side in the rotation direction S1 of the developing sleeve 132 ′ in a cross section intersecting (orthogonal in the illustrated example) with respect to the axis 132a of the developing sleeve 132 ′ along the circumferential direction of the developing sleeve 132 ′. 140 and a virtual plane 145 connecting the axis 132a of the developing sleeve 132 ′ and the bottom 139a of the recess 139 ′ are formed at 60 degrees, and the rotation of the developing sleeve 132 ′ A second angle θ2 formed by the downstream inner surface 141 located on the downstream side in the direction S1 and the virtual surface 145 is formed at 30 degrees. As described above, the first angle θ1 of the developing sleeve 132 'is formed larger than the second angle θ2. That is, the third angle θ3 formed by the upstream inner surface 140 on the upstream side in the rotation direction S1 of the developing sleeve 132 ′ and the outer surface of the developing sleeve 132 ′ connected to the upstream inner surface 140 is formed at 30 degrees. At the same time, a fourth angle θ4 formed by the downstream inner surface 141 on the downstream side in the rotation direction S1 of the developing sleeve 132 ′ and the outer surface of the developing sleeve 132 ′ connected to the downstream inner surface 141 is formed at 60 degrees. . As described above, the third angle θ3 of the developing sleeve 132 'is formed smaller than the fourth angle θ4. The developing sleeve 132 'shown in the second embodiment described above corresponds to the product 3 of the present invention described later.

  When such a developing sleeve 132 ′ is formed, as shown in FIG. 14, the developing sleeve 132 ′ moves the position of the end mill 21 relative to the developing sleeve 132 ′ from the upstream side in the rotational direction S1 of the developing sleeve 132 ′. After being shifted to the side, the developing sleeve 132 is disposed at a position intersecting (orthogonal in the illustrated example) with respect to the end mill 21, so that the axis 132a of the developing sleeve 132 ′ along the circumferential direction of the developing sleeve 132 ′. , The upstream inner surface 140 located on the upstream side in the rotation direction S1 of the developing sleeve 132 ′, the axial core 132a of the developing sleeve 132 ′, and the bottom 139a of the recess 139 ′. The first angle θ1 formed by the virtual plane 145 connecting the two and the inner surface of the downstream side in the downstream direction of the developing sleeve 132 in the rotation direction S1. And 141, and the virtual plane 145, but may be larger than the second angle θ2 formed.

  According to the second embodiment, an imaginary surface that connects the upstream inner surface 140 positioned upstream in the rotation direction S1 of the developing sleeve 132 ′, the shaft 132a of the developing sleeve 132 ′, and the bottom 139a of the recess 139 ′. A first angle θ <b> 1 formed by 145 is formed larger than a second angle θ <b> 2 formed by the downstream inner surface 141 located on the downstream side in the rotation direction S <b> 1 of the developing sleeve 132 and the virtual surface 145. In this way, the upstream inner surface 140 located upstream in the rotation direction S1 of the developing sleeve 132 ′ and the virtual surface 145 connecting the shaft 132a of the developing sleeve 132 ′ and the bottom 139a of the recess 139 ′ are formed. The first angle θ1 is larger than the second angle θ2 formed by the downstream inner surface 141 located on the downstream side in the rotation direction S1 of the developing sleeve 132 ′ and the virtual surface 145 (that is, the upstream inner surface 140 becomes gentler. By forming the first inner surface 140), it is possible to suppress wear of the upstream inner surface 140, which has a large amount of wear due to aging. In this way, it is possible to suppress a decrease in image density due to aging.

  In the second embodiment described above, the radii of curvature R1 and R2 of the boundary portion 143 on the upstream side in the rotational direction S1 of the developing sleeve 132 ′ and the boundary portion 144 on the downstream side in the rotational direction S1 of the developing sleeve 132 are In the present invention, the radius of curvature R1 of the boundary portion 143 on the upstream side in the rotational direction S1 of the developing sleeve 132 is formed to be 0.1 mm, and the rotational direction of the developing sleeve 132 is formed in the present invention. The radius of curvature R2 of the boundary portion 144 on the downstream side of S1 may be formed to 0.05 mm. As described above, the curvature radius R1 of the boundary portion 143 on the upstream side in the rotation direction S1 of the developing sleeve 132 may be larger than the curvature radius R2 of the boundary portion 144 on the downstream side in the rotation direction S1 of the development sleeve 132. good. The developing sleeve 132 in which the radius of curvature R1 of the boundary portion 143 is formed to be 0.10 mm and the radius of curvature R2 of the boundary portion 144 is formed to be 0.05 mm corresponds to the product 4 of the present invention described later. To do.

  In order to form the developing sleeve 132 in which the curvature radius R1 of the boundary portion 143 is formed to 0.10 mm and the curvature radius R2 of the boundary portion 144 is formed to 0.05 mm, the surface treatment apparatus 1 is used. However, when the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139 are polished, the developing sleeve 132 is rotated only in the same direction as the rotation direction S1, so that the radius of curvature R1 of the boundary portion 143 is set. The radius of curvature R2 of the boundary portion 144 can be larger.

  According to the developing sleeve 132 in which the radius of curvature R1 of the boundary portion 143 is formed to be 0.10 mm and the radius of curvature R2 of the boundary portion 144 is formed to be 0.05 mm, the rotation direction of the developing sleeve 132 is The curvature radius R1 of the boundary portion 143 on the upstream side of S1 is formed larger than the curvature radius R2 of the boundary portion 144 on the downstream side in the rotation direction S1 of the developing sleeve 132. The amount of wear of the boundary portions 143 and 144 due to use over time is greater on the upstream side than on the downstream side in the rotation direction S1 of the developing sleeve 132. Therefore, the curvature radius R1 of the boundary portion 143 on the upstream side in the rotation direction S1 of the developing sleeve 143 in advance. Is formed larger than the radius of curvature R2 of the boundary portion 144 on the downstream side in the rotation direction S1 of the developing sleeve 132, so that wear of the boundary portion 143 due to aging is suppressed, thereby reducing the developer conveyance amount. Can be suppressed. In this way, a decrease in image density can be suppressed.

  Further, according to the developing sleeve 132 in which the radius of curvature R1 of the boundary portion 143 is formed to 0.10 mm and the radius of curvature R2 of the boundary portion 144 is formed to 0.05 mm, the surface treatment apparatus 1 is used. However, when the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139 are polished, the developing sleeve 132 is rotated only in the same direction as the rotation direction S1, so that the curvature radius R1 of the boundary portion 143 is increased. However, it may be formed larger than the radius of curvature R2 of the boundary portion 144. Thus, the curvature radius R1 of the boundary portion 143 formed larger than the curvature radius R2 of the boundary portion 144 is positioned upstream of the rotation direction S1 in which the image forming apparatus 101 rotates the developing sleeve 132 when forming an image. Thus, the developing sleeve 132 can be used efficiently.

  Further, in the above-described embodiment, the circumferential cross-sectional shape of the developing sleeve 132 of the recess 139 is formed in an arc shape, but in the present invention, as shown in FIGS. 15 (a) to 15 (c). The cross-sectional shape of the recess 139 in the circumferential direction of the developing sleeve 132 may be V-shaped. In the illustrated example, 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 a circular cross-sectional shape in the longitudinal direction (that is, the longitudinal direction of the developing sleeve 132). It is formed in an arcuate curved surface. In this case, as shown in FIGS. 16A and 16B, the cross-sectional shape of the outer edge 25 of the tip of the cutting blade 24 of the end mill 21 is formed to form an acute angle, so that the recess 139 is formed. The developing sleeve 132 has a V-shaped cross section in the circumferential direction. In FIGS. 15 to 16, the same parts as those in the first and second embodiments described above are denoted by the same reference numerals.

  15 to 16, 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 the longitudinal direction (that is, the developing sleeve 132). Since the cross-sectional shape in the longitudinal direction) is an arc-shaped curved surface, the amount of the developer 126 that can be accommodated in the recess 139 can be increased. Thus, the developing sleeve 132 can carry a sufficient amount of the developer 126.

  Further, in the above-described embodiment, the circumferential cross-sectional shape of the developing sleeve 132 of the recess 139 is formed in an arc shape. However, in the present invention, the shape of the outer edge 25 of the cutting blade 24 can be changed as appropriate. 17 and 18, the circumferential cross-sectional shape of the developing sleeve 132 of the recess 139 may be changed as appropriate. FIG. 17 shows a case where the bottom of the V-shaped recess 139 is formed flat, and FIG. 18 shows a case where the bottom of the V-shaped recess 139 is formed in an arc shape. In FIG. 17 and FIG. 18, the same parts as those in the first and second embodiments described above are denoted by the same reference numerals and description thereof is omitted.

  Further, in the above-described embodiment, the motors 2 and 20 and the moving actuator are continuously operated at the same time so that the recesses 139 are spirally arranged on the outer surface of the developing sleeve 132, and each of the recesses 139 is slightly arcuate. However, in the present invention, as shown in FIGS. 19 and 20, the motors 2, 20 and the moving actuator are operated appropriately and appropriately so that the recess 139 is formed in the longitudinal direction of the developing sleeve 132. And a plurality of dents 139 may be arranged on the straight line along the circumferential direction of the developing sleeve 132.

  In the embodiment described above, the planar shape of the recess 139 is formed in an elliptical shape. However, in the present invention, the planar shape may be formed in a circular shape as shown in FIG.

  Further, in the above-described embodiment, the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 are arranged so as to be shifted by about half the length of the recess 139. However, in the present invention, the recesses 139 adjacent to each other in the circumferential direction of the developing sleeve 132 may be arranged at an arbitrary position such as 1/3 or 1/4 of the length of the recess 139. .

  In the above-described embodiment, the developing sleeve 132 is disposed so that the interval between the recesses 139 adjacent to each other in the circumferential direction and the longitudinal direction is constant. That is, the recesses 139 are regularly arranged. However, in the present invention, the developing sleeve 132 may not be arranged so that the interval between the adjacent recesses 139 in the circumferential direction and the longitudinal direction is constant. That is, the recesses 139 may be irregularly arranged.

  Further, in the above-described embodiment, the end mill 21 is moved along the longitudinal direction of the developing sleeve 132 to move the end mill 21 and the developing sleeve 132 relatively. Of course, in the present invention, the end mill 21 is also moved. 21 and the developing sleeve 132 may be moved along the longitudinal direction of the developing sleeve 132 to relatively move them.

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

  Incidentally, the recent image forming apparatus 101 has a demand for further higher speed and higher durability, and further requires a longer life of the developing sleeve 132. Accordingly, the inventors of the present invention observed the developing sleeve 132 after aged use. As a result, the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139 after the aged use are the developing sleeve 132 in the initial state. It was discovered that the outer surfaces of the rims 139 and 144 are rounder than the boundaries 143 and 144. For this reason, the inventors of the present invention use the developing roller 115 having the developing sleeve 132 shown in Comparative Example 1 described later to form an outer surface of the developing sleeve 132 after forming a predetermined number of sheets. The curvature radius R1 of the boundary portion 143 between the dent 139 and the dent 139 was measured.

  In forming an image, a magnetic carrier 135 having an average volume particle size of 35 μm having a resin coating layer containing a charge control agent using ferrite as a shaft agent, a charge control agent containing a polyester as a main component by an emulsion polymerization method, a color A developer 126 composed of a toner having an average volume particle size of 5 μm was used by mixing the agent and externally adding silica, titanium oxide, or the like. The toner concentration was adjusted to 7% by weight.

(Comparative Example 1)
In Comparative Example 1 shown in Table 1 to be described later, as shown in FIG. 22, the radii of curvature R1 and R2 of the boundary portions 143 and 144 of the recess 139 are each formed to 0.02 mm, and the angle θ1, A recess 139 is formed in which each θ2 is formed at 45 degrees. In FIG. 22, the toner adsorbed on the magnetic carrier 135 is omitted.

  The results are shown in FIG. FIG. 23 shows the relationship between the radius of curvature R1 of the boundary portion 143 between the outer surface of the developing sleeve 132 and the recess 139 and the number of sheets fed by the image forming apparatus 101. As the number of sheets fed by the image forming apparatus 101 increases, the radius of curvature R1 of the boundary portion 143 between the outer surface of the developing sleeve 132 and the recess 139 increases. However, the boundary portion 143 does not continue to be worn to any extent, and when the radius of curvature R1 of the boundary portion 143 is larger than the volume average particle diameter of the magnetic carrier 135, the outer surface of the magnetic carrier 135 and the outer surface of the developing sleeve 132 are reduced. It became clear that the contact area increased and the wear of the boundary portion 143 slowed down.

  Next, the inventors of the present invention manufacture a plurality of developing sleeves 132 in which the radii of curvature R1 and R2 of the boundary portions 143 and 144 are variously changed and the first angle θ1 and the second angle θ2 are variously changed. Then, a test image of the developing sleeve 132 in an initial state and a test image after continuous use (3,000,000 sheets are fed (that is, the developing roller 115 is rotated 45,000,000)) are formed. The results are shown in Table 1. The above-described Comparative Example 1 is assigned the same reference numerals and description thereof is omitted.

(Comparative Example 2)
In Comparative Example 2 shown in Table 1, the radii of curvature R1 and R2 of the recess 139 are each 0.02 mm, the first angle θ1 is formed at 60 degrees, and the second angle θ2 is 30. The developing sleeve 132 is formed each time.

(Invention product 1)
The product 1 of the present invention shown in Table 1 is the developing sleeve 132 shown in the first embodiment described above. In the product 1 of the present invention, the radii of curvature R1 and R2 of the recess 139 are each formed to be 0.1 mm, and the first angle θ1 and the second angle θ2 are each formed to be 45 degrees.

(Invention product 2)
In the product 2 of the present invention, the curvature radius R1 of the boundary portion 143 of the developing sleeve 132 is formed to be 0.1 mm, and the curvature radius R2 of the boundary portion 144 is formed to be 0.05 mm, and the first angle θ1 and The second angle θ2 is the developing sleeve 132 that is formed at 45 degrees.

(Invention product 3)
The product 3 of the present invention shown in Table 1 is the developing sleeve 132 ′ shown in the second embodiment described above. In the product 3 of the present invention, the radii of curvature R1 and R2 of the recess 139 are each formed to 0.1 mm, the first angle θ1 is formed to 60 degrees, and the second angle θ2 is formed to 30 degrees. The developing sleeve 132 ′.

(Invention product 4)
The invention product 4 shown in Table 1 is a development in which the radius of curvature R1 of the boundary portion 143 described above is formed to 0.10 mm and the radius of curvature R2 of the boundary portion 144 is formed to 0.05 mm. A sleeve 132. In the product 4 of the present invention, the radius of curvature R1 of the boundary portion 143 is formed to be 0.10 mm, the radius of curvature R2 of the boundary portion 144 is formed to be 0.05 mm, and the first angle θ1 is 60. The developing sleeve 132 has a second angle θ2 of 30 degrees.

  Inventive product 1 to inventive product 4 and Comparative Examples 1 to 2 described above use the end mill 21 having an outer diameter of 2 mm, the rotation speed of the developing sleeve 132 is 240 rpm, the rotation speed of the end mill 21 is 21300 rpm, The surface treatment apparatus 1 is driven at a moving speed in the longitudinal direction of the developing sleeve 132 of the end mill 21 of 0.5 mm / rev (rotation) to form a recess 139 in the developing sleeve 132 made of an aluminum alloy having an outer diameter of 25 mm. did. At this time, the end mill 21 with respect to the developing sleeve 132 is positioned at a position intersecting (orthogonal in the illustrated example) with respect to the developing sleeve 132. Thereafter, using the fiber sander 26, the rotation speed of the developing sleeve 132 is set to 400 rpm, the rotation speed of the fiber sander 26 is set to 15000 rpm, and the moving speed in the longitudinal direction of the developing sleeve 132 of the fiber sander 26 is 1 mm / rev (rotation). The surface treatment apparatus 1 was driven to polish the boundary portions 143 and 144 between the outer surface of the developing sleeve 132 and the recess 139. At this time, a fiber sander 26 having an outer diameter of 20 mm and a particle size of 320 was used.

  Further, the developing sleeve 132 is formed in an arc shape having a curvature radius of 1.0 mm in the longitudinal cross section, the interval between the circumferential recesses 139 of the developing sleeve 132 is 0.22 mm, and the developing sleeve 132 is arranged in the longitudinal direction. The recesses 139 are arranged so that the interval between the recesses 139 is 0.5 mm.

  In forming an image, a magnetic carrier 135 having an average volume particle size of 35 μm having a resin coating layer containing a charge control agent using ferrite as a shaft agent, a charge control agent containing a polyester as a main component by an emulsion polymerization method, a color A developer 126 composed of a toner having an average volume particle size of 5 μm was used by mixing the agent and externally adding silica, titanium oxide, or the like. The toner concentration was adjusted to 7% by weight and mixed with a Henschel mixer. The process conditions were such that the photoreceptor surface potential was fixed at −700 V, the exposure potential was −150 V, and the developing bias was fixed at −550 V.

  In the results shown in Table 1, the density unevenness of the image formed by the image forming apparatus 101 using the developing roller 115 including the developing sleeve 132 of the following Invention 1 to Invention 4 and Comparative Example 1 to Comparative Example 2 is shown. Also, the image density reduction after feeding 3,000,000 sheets (that is, 45,000,000 rotations of the developing roller 115) was evaluated.

  In the evaluation of the image, a so-called solid image having a uniform density with one color was output, density measurement was performed with a spectral densitometer at six locations of the solid image, and the average value at the six locations was used as the density. As shown in Table 1, density measurement is performed at the initial stage and after feeding 3,000,000 sheets (that is, 45,000,000 rotations of the developing roller 115). When the decrease was less than 10%, ◎, when it was less than 15%, ◯, and when it was 15% or more, x.

  When the image forming apparatus 101 formed an image using the developing roller 115 obtained by accommodating the magnet roller 133 in the developing sleeve 132 of Comparative Example 1 or Comparative Example 2, the density after feeding 3,000,000 sheets A drop occurred.

  When the image forming apparatus 101 formed an image using the developing roller 115 obtained by accommodating the magnet roller 133 in the developing sleeves 132 and 132 ′ of the inventive product 1 to the inventive product 4, 3,000,000 sheets were supplied. After the paper, it was confirmed that the density did not decrease and a good image with no shading unevenness was obtained. In addition, it was confirmed that the product 3 of the present invention and the product 4 of the present invention can obtain a better image without density unevenness than the products 1 and 2 of the present invention.

  According to the present invention described above, in Comparative Example 1 and Comparative Example 2, the radii of curvature R1 and R2 of the boundary portions 143 and 144 of the recess 139 are formed to be smaller than the volume average particle diameter of the magnetic carrier 135. On the other hand, in the products 1 to 4 of the present invention, the radii of curvature R1 and R2 of the boundary portions 143 and 144 of the recess 139 are formed larger than the volume average particle diameter of the magnetic carrier. Then, when the radii of curvature R1 and R2 of the boundary portions 143 and 144 of the recess 139 become larger than the volume average particle diameter of the magnetic carrier 135, the wear of the boundary portions 143 and 144 is slowed down. By forming the curvature radii R1 and R2 of 143 and 144 larger than the volume average particle diameter of the magnetic carrier 135, it becomes clear that the wear of the boundary portions 143 and 144 is dulled, and the concentration does not decrease. It was.

  In addition, the first angle θ1 of the products 3 and 4 of the present invention is formed at 60 degrees, and the second angle θ2 is formed at 30 degrees, and the first angle θ1 is larger than the second angle θ2. It is formed at an angle. In contrast, the first angle θ1 and the second angle θ2 of the product 1 of the present invention and the product 2 of the present invention are each formed at 45 degrees. When the image forming apparatus 101 forms an image, the developing sleeve 132 has an upstream inner surface 140 on the upstream side in the rotation direction S1 of the developing sleeve 132 and a downstream inner surface on the downstream side in the rotation direction S1. The amount of wear is greater than 141. For this reason, the first angle θ1 is formed in advance at an angle larger than the second angle θ2 (that is, the upstream inner surface 140 is formed to have a gentler slope than the downstream inner surface 141). It became clear that the wear was slowed down and no decrease in concentration occurred.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

21 End mill (rotary tool)
101 Image forming apparatus 106Y, 106M, 106C, 106K Process cartridge 108 Photosensitive drum (photosensitive member)
109 Charging roller (charging device)
113 Developing Device 115 Developing Roller 132, 132 ′ Developing Sleeve 132a Axle Core 133 Magnet Roller 135 Magnetic Carrier 139 Recess 139a Bottom 140 Upstream Inner Surface 141 Downstream Inner Surface 143, 144 Boundary 145 Virtual Surface θ1 First Angle θ2 Second Angle R1 , R2 radius of curvature S1 direction of rotation

JP 2003-255692 A JP 2004-191835 A JP 2007-86091 A

Claims (13)

(A) a magnet roller; and (b) a magnetic carrier that encloses the magnet roller and attracts toner to the outer surface by the magnetic force of the magnet roller. In a developing roller provided with a large number of developing sleeves spaced apart so as not to overlap,
In the circumferential cross section of the developing sleeve, the boundary between the outer surface and the circular or oval dent in plan view is polished using a fiber sander and formed into a rounded curved surface. A developing roller.   The developing roller according to claim 1, wherein a radius of curvature of the boundary portion formed on the rounded curved surface is larger than a volume average particle diameter of the magnetic carrier.   2. The radius of curvature of the boundary portion on the upstream side in the rotation direction of the developing sleeve is greater than the radius of curvature of the boundary portion on the downstream side in the rotation direction of the developing sleeve. Alternatively, the developing roller according to claim 2. A first angle formed by an upstream inner surface located on the upstream side in the rotational direction in the circumferential cross section of the developing sleeve and a virtual plane connecting the axial center of the developing sleeve and the bottom of the recess,
2. The apparatus according to claim 1, wherein the developing sleeve is configured to have a larger angle than a second angle formed by a downstream inner surface located on the downstream side in the rotation direction in the circumferential section of the developing sleeve and the virtual surface. Item 4. The developing roller according to Item 3.   The cross-sectional shape of the developing sleeve in the circumferential direction of the recess is formed in an arc shape, and the cross-sectional shape of the developing sleeve in the longitudinal direction of the circular or elliptical recess in the plan view is formed in an arc shape. The developing roller according to any one of claims 1 to 4, wherein the developing roller is characterized in that:   The cross-sectional shape in the circumferential direction of the developing sleeve in the circular or elliptical recess in plan view is formed in a V shape, and the cross-sectional shape in the longitudinal direction of the developing sleeve in the recess is formed in an arc shape. The developing roller according to any one of claims 1 to 4, wherein the developing roller is provided.   The circular or elliptical recesses in plan view adjacent to each other in the circumferential direction of the developing sleeve are disposed at positions shifted in the longitudinal direction of the developing sleeve. The developing roller according to any one of 6.   The developing roller according to claim 7, wherein the recess in a circular shape or an elliptical shape in plan view is spirally disposed on an outer surface of the developing sleeve.   9. The dent in a circular or elliptical shape in plan view is formed by cutting the outer surface of the developing sleeve with a rotary tool rotated around an axis. The developing roller as described in any one of them.   While the developing sleeve arranged so that the circular or elliptical depression in plan view intersects the axis of the rotating tool is rotated around the axis, the rotating tool and the developing sleeve are connected to the developing sleeve. The developing roller according to claim 9, wherein the developing roller is formed to be relatively moved in the longitudinal direction.   11. The developing roller according to claim 1, wherein the developing roller includes a developing roller having a developing sleeve that adsorbs a magnetic carrier having toner adsorbed on an outer surface. A developing device comprising:   A process cartridge having at least a developing device, wherein the developing device includes the developing device according to claim 11.   An image forming apparatus having at least a photosensitive drum, a charging device, and a developing device, wherein the developing device includes the developing device according to claim 11.

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