JP2008145530A - Developer carrier, developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer carrier of a surface shape capable of increasing strength in the longitudinal direction (the thrust direction) even when a groove pattern of a twill line shape is formed in a surface thereof. <P>SOLUTION: The developer carrier has a pattern of grooves 32 of a twill line shape formed in a surface thereof by crossing a plurality of grooves formed aslope at an acute angle to the rotation center axis (thrust direction) 33 and a plurality of grooves formed aslope at an acute angle on the opposite side to the thrust direction, and rotates while holding a developer by the groove pattern of the twill line shape, wherein each surface portion surrounded by the grooves 32 of the groove pattern of the twill line shape is a rhombic protrusion 31, and one end of a certain rhombic protrusion 36 in the thrust direction and one end of an adjacent rhombic protrusion 37 in the thrust direction are connected with a protrusion 40 extending in the thrust direction to provide a portion not forming a groove. By this configuration, the developer carrier can be increased in strength in the longitudinal direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developer carrying member that holds and rotates at least a developer containing toner particles, a developing device that develops a latent image on the image carrier using the developer carrying member, and a process having the developing device. The present invention relates to an image forming apparatus such as a cartridge, a developing device or a copier, a printer, a plotter, a facsimile, or a complex machine including the process cartridge.

  In an image forming apparatus configured as a copying machine, a printer, a plotter, a facsimile, or a multifunction machine having at least one of these functions using an electrophotographic system, a photosensitive member as an image carrier is used as a charging unit. After charging, a latent image is formed by exposure of a document image or optical writing according to image information, and the latent image is developed with a developer containing toner of a developing unit to form a visible image. The toner image is transferred directly to a transfer material such as transfer paper or via an intermediate transfer member, and the image transferred to the transfer material is fixed to form an image.

In such an electrophotographic image forming apparatus, in recent years, the demand for high image quality and high reliability has been very high, and the role played by the developing device in terms of high image quality is very large. There are the following.
1. Dot reproducibility.
2. Amount of toner adhering to the photoreceptor without unevenness in the page.
3. Reduce developer stress over time.

In order to achieve such a problem, as a surface pattern of a conventional developer carrier (for example, a developing roller), a sandblast or a V groove pattern parallel to the rotation center axis of the developing roller is provided on the entire circumference. What was provided was common.
However, the problems with the surface of the conventional developing roller as described above are related to the development roller with sand blasting that has unevenness, and if the amount of unevenness is small, the developer conveying ability decreases, and the unevenness is caused by increasing the developer conveying ability. When the amount is increased, there is a problem that the developing roller is deformed during processing. As for the V groove pattern parallel to the rotation center axis of the developing roller, the V groove for conveying the developer is parallel to the developer regulating member such as a doctor blade and passes over the regulating member at the same moment. Therefore, there is a problem that the stress on the developer is deteriorated and pitch unevenness occurs around the developing roller due to a groove deviation at the time of processing. In particular, when the developing roller is formed of a cylindrical developing sleeve, the above problem appears remarkably.

  In order to solve such a conventional technical problem, a developing roller having an iris-shaped groove pattern in which a plurality of grooves intersect with the rotation center axis of the developing roller or a surface shape of a groove pattern having a shape close thereto is (or Various developing sleeves, developing devices using the same, and image forming apparatuses have been proposed (for example, conventional techniques described in Patent Documents 1 to 4).

JP 2003-316146 A JP 2003-208021 A JP 2000-242073 A Japanese Unexamined Patent Publication No. 07-13410

  With respect to the developing roller having the iris shape groove pattern as described above or the surface shape of the groove pattern close to that, a conventional sandblast or parallel V-groove pattern was formed by giving the groove shape a characteristic. Although the developing roller is superior to the developing roller in terms of improvement in developer conveying capability and less stress on the developer, there are problems inherent to the developing roller. The problem will be described below.

FIG. 7 shows an enlarged state of the surface of the developing roller having the iris-shaped groove pattern. Since the iris-shaped groove pattern is a roller cut so that a plurality of inclined grooves intersect, the convex portion is a combination of diamond-shaped patterns when viewed in the longitudinal direction of the developing roller. For this reason, when the developing roller is constituted by a cylindrical developing sleeve, although depending on the groove interval, the angle of the iris shape, and the groove depth, a thin portion in the longitudinal direction of the sleeve is seen in a certain straight line shape. Therefore, the strength of the sleeve is inferior to that of a conventional developing roller having a sandblast or a parallel V-groove pattern.
In recent years, the distance between the photosensitive member surface and the developing roller surface (development gap) has become narrower due to the trend toward higher image quality. Therefore, a developing roller having an iris-shaped groove pattern formed by the developer pressure on the developing nip. The center portion of the developing sleeve (especially the developing sleeve) is likely to bend, and in order to compensate for the side effects, the sleeve material is strengthened and the wall thickness is increased. On the other hand, if the thickness is not increased, the developing ability at the central part and the end part in the longitudinal direction will be different due to the bending of the central part.In order to guarantee the image density in the central part, the amount of developer is increased. Therefore, there is a problem that the developer adhesion amount at the roller end becomes excessive.

The present invention has been made to solve the above-described problems of the prior art, and increases the strength in the longitudinal direction (rotation center axis direction) even when an iris-shaped groove pattern is provided on the surface. And a developer carrier having a surface shape capable of increasing the strength efficiently and maximizing the strength of the developer carrier. For the purpose.
Another object of the present invention is to provide a developing device capable of performing stable development using the developer carrying member, and a process cartridge provided with the developing device. Furthermore, the developing device or the process cartridge is provided. An object of the present invention is to provide an image forming apparatus capable of forming a high-quality and highly reliable image using the image forming apparatus.

In order to achieve the above object, the present invention employs the following solutions.
The first means of the present invention includes a plurality of grooves formed at an acute angle with respect to a rotation center axis direction (hereinafter referred to as a thrust direction), and an acute angle at an opposite side to the thrust direction. A developer carrier having a iris-shaped groove pattern formed on the surface and intersecting with a plurality of grooves formed in the manner and holding the developer by the iris-shaped groove pattern and rotating the surface. The portion surrounded by the groove of the iris-shaped groove pattern is a rhombus-shaped convex portion, one end point of the rhomboid-shaped convex portion in the thrust direction, and the rhombus shape adjacent to the rhombus-shaped convex portion A protrusion portion extending in the thrust direction is connected to one end point of the protrusion portion in the thrust direction, and a portion not forming a groove is provided.

  According to a second means of the present invention, in the developer carrier of the first means, one end point in the thrust direction of the rhombic convex portion of the iris-shaped groove pattern and a rhomboid convex adjacent to the rhomboid shape. A developer carrying member, characterized in that a portion not formed with a groove by connecting one end point in the thrust direction of the portion with a convex portion extending in the thrust direction is provided continuously in the thrust direction.

  According to a third means of the present invention, in the developer carrier of the first or second means, one end point in the thrust direction of the rhomboid convex portion of the iris-shaped groove pattern and a rhombus adjacent to the rhombus shape The shape where one end point in the thrust direction of the shape is connected by a protrusion extending in the thrust direction and does not form a groove is provided continuously in the thrust direction, and is provided continuously in the thrust direction Is provided over the entire surface.

According to a fourth means of the present invention, there is provided a developer carrying member that holds and rotates a developer, a developer container that contains the developer, and a developer that conveys the developer contained in the developer container while stirring the developer. In the developing device having the developer conveying means and the developer regulating means for regulating the amount of the developer on the developer carrying body to a fixed amount, any one of the first to third as the developer carrying body. The developer carrying member of the means is used.
According to a fifth means of the present invention, in the developing device of the fourth means, the developer is a two-component developer composed of toner particles and magnetic particles, and the developer carrier has the surface shape. It is a cylindrical developing sleeve, and has a magnetic field generating means inside the developing sleeve.

  According to a sixth aspect of the present invention, there is provided a process in which the image carrier, the developing unit, and at least one unit selected from the charging unit and the cleaning unit are integrally supported and detachably attached to the image forming apparatus main body. The cartridge includes a developing device of a fourth or fifth means as the developing means.

According to a seventh aspect of the present invention, in the image forming apparatus including the image forming unit that forms a latent image on the image carrier and develops the latent image to form a visible image, the image forming unit includes: A developing device of 4th or 5th means or a process cartridge of 6th means is provided.
According to an eighth aspect of the present invention, there is provided an image forming apparatus including a plurality of image forming units that form a latent image on an image carrier and develop the latent image to form a visible image. The forming unit includes a developing device of the fourth or fifth means, or a process cartridge of the sixth means.

According to a ninth means of the present invention, in the image forming apparatus of the seventh or eighth means, the toner used in the developing device or the process cartridge has a volume average particle diameter of 3 to 8 μm and a volume average particle diameter ( The ratio (Dv / Dn) of Dv) to the number average particle diameter (Dn) is in the range of 1.00 to 1.40.
According to a tenth means of the present invention, in the image forming apparatus of the seventh or eighth means, the toner used in the developing device or the process cartridge has a shape factor SF-1 in the range of 100 to 180. The shape factor SF-2 is in the range of 100 to 180.

  In the developer carrier of the first means of the present invention, the portion surrounded by the groove of the iris-shaped groove pattern on the surface is a rhombus-shaped convex portion, and the rhomboid-shaped convex portion in the thrust direction is formed. By providing a portion where one end point and one end point in the thrust direction of the rhombus-shaped convex portion adjacent to the rhombus-shaped convex portion are connected by the convex portion extending in the thrust direction and do not form a groove, In addition to increasing the strength of the developer carrying member in the thrust direction (longitudinal direction) and making the developer carrying member thinner, it is possible to suppress the difference in the amount of developer adhering between the central portion and the end portion in the longitudinal direction. It becomes possible.

  In the developer carrier of the second means of the present invention, in addition to the configuration and effects of the first means, one end point in the thrust direction of the rhomboid convex portion of the iris-shaped groove pattern and the rhomboid shape are adjacent to each other. A portion in which the one end point in the thrust direction of the matching rhombus-shaped convex portion is connected by the convex portion extending in the thrust direction and does not form a groove is provided continuously in the thrust direction. The strength in the thrust direction (longitudinal direction) of the carrier can be increased efficiently, the developer carrier can be thinned efficiently, and the material can be reduced.

  In the developer carrier of the third means of the present invention, in addition to the configuration and effect of the first or second means, one end point in the thrust direction of the rhombic convex portion of the iris-shaped groove pattern, and the rhombus The one end point in the thrust direction of the rhombus shape adjacent to the shape is connected by a convex portion extending in the thrust direction, and a portion not forming a groove is continuously provided in the thrust direction, and is continuous in the thrust direction. By providing the shape provided on the entire surface, the strength in the thrust direction (longitudinal direction) of the developer carrier can be maximally enhanced, and the material reduction effect can be maximized. Is possible.

In the developing device of the fourth means of the present invention, the developer carrier of any one of the first to third means is used as the developer carrier, so that the thrust direction (longitudinal direction) of the developer carrier is obtained. ) Can be increased, the deflection of the central portion can be reduced, the difference in developing ability between the central portion and the end portion in the longitudinal direction can be reduced, and stable development can be performed.
In the developing device of the fifth means of the present invention, even when a two-component developer consisting of toner particles and magnetic particles is used as the developer and the developer carrying member is a cylindrical developing sleeve, the thrust of the developing sleeve is also provided. The strength in the direction (longitudinal direction) is increased, stable development can be performed, and the developing sleeve can be thinned.

  In the process cartridge of the sixth means of the present invention, by providing the developing device of the fourth or fifth means as the developing means, it is possible to perform stable development and provide a highly reliable process cartridge. be able to.

In the image forming apparatus of the seventh means of the present invention, the image forming unit is provided with the developing device of the fourth or fifth means or the process cartridge of the sixth means, so that stable development can be performed. It is possible to perform image formation with high image quality and high reliability.
In the image forming apparatus of the eighth means of the present invention, each of the image forming units is provided with the developing device of the fourth or fifth means or the process cartridge of the sixth means in the plurality of image forming portions. Therefore, it is possible to perform stable development at a part, and it is possible to perform color image formation with high image quality and high reliability.

In the image forming apparatus of the ninth means of the present invention, in addition to the constitution of the seventh or eighth means, the toner used in the developing device or the process cartridge has a volume average particle diameter of 3 to 8 μm and a volume average An image using a high-quality toner that defines the particle size distribution when the ratio (Dv / Dn) of the particle size (Dv) to the number average particle size (Dn) is in the range of 1.00 to 1.40. Formation is possible.
In the image forming apparatus of the tenth means of the present invention, in addition to the structure of the seventh or eighth means, the toner used in the developing device or the process cartridge has a shape factor SF-1 of 100 to 180. If the shape factor SF-2 is in the range of 100 to 180, image formation using high-quality toner that defines the toner shape is possible.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
First, an embodiment of an image forming apparatus including a developing device or a process cartridge using the developer carrying member of the present invention will be described.

FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. The image forming apparatus shown in FIG. 1 includes an intermediate transfer belt 5 that is an intermediate transfer member that is stretched around a plurality of rollers 5a, 5b, and 5c, and a plurality of image forming units arranged along the intermediate transfer belt 5. A plurality of image forming units, each of which is a photoconductor 1a, 1b, 1c, 1d that is an image carrier, and charging means 2a, 2b, 2c, 2d. Latent image forming means 3 (3a, 3b, 3c, 3d), developing means 4a, 4b, 4c, 4d, primary transfer means 12a, 12b, 12c, 12d, and cleaning means 9a, 9b, 9c, 9d. A monochrome image (for example, an image of each color of yellow, magenta, cyan, and black) is formed on each of the photoconductors 1a, 1b, 1c, and 1d of each image forming unit, and these monochrome images are formed on the intermediate transfer belt 5; After transferred sequentially superimposed, the image on the intermediate transfer belt, and collectively transferred to a transfer material such as transfer paper P at the secondary transfer unit 7, to form a color image.
In FIG. 1, only the color image forming unit is shown and functions as a color printer, a color plotter, or the like. However, by installing a document image reading unit (not shown) on the image forming unit, color copying is performed. By providing a communication function and a function of a facsimile machine or a multifunction machine.

  More specifically, in each image forming unit, the photoconductors 1a, 1b, 1c, and 1d are uniformly charged by charging means (for example, charging rollers) 2a, 2b, 2c, and 2d, and then the photoconductor 1a. , 1b, 1c, and 1d, optical latent images are optically formed by the optical writing means 3 (writing positions 3a, 3b, 3c, and 3d), and developer carriers (developing means 4a, 4b, 4c, and 4d) ( For example, the latent image is developed with a developer containing toner carried by a developing roller, and a visualized image of the toner is formed. The toner images formed on the photoreceptors 1a, 1b, 1c, and 1d are temporarily transferred to the intermediate transfer belt 5 by primary transfer means (for example, primary transfer rollers) 12a, 12b, 12c, and 12d. In synchronization with this image forming operation, a transfer material (for example, transfer paper) P is fed from a paper feed unit (not shown), and conveyed to the secondary transfer unit through the registration roller pair 6. Then, the toner image on the intermediate transfer belt 5 is transferred to the transferred transfer paper P by secondary transfer means (for example, a secondary transfer belt stretched around a plurality of rollers 7a, 7b, 7c) 7. . The toner image transferred onto the transfer paper P is conveyed to the fixing means 8 by the secondary transfer belt 7, and the toner image on the transfer paper P is fixed by heat or pressure. The fixing transfer paper P is discharged to a paper discharge unit (not shown).

  On the other hand, untransferred toner that has not been transferred to the intermediate transfer belt 5 on each of the photoconductors 1a, 1b, 1c, and 1d is scraped from the photoconductor by cleaning means (for example, photoconductor cleaning blades) 9a, 9b, 9c, and 9d. Be dropped. The residual charge on the photoconductor is neutralized by a neutralizing unit (not shown) to prepare for the next image forming operation.

  Untransferred toner scraped off from the photosensitive member by the photosensitive member cleaning blades 9a, 9b, 9c, and 9d passes through the collected toner conveyance path 14 (14a, 14b, 14c, 14d) and is stored in the waste toner storage container 15. The Further, the untransferred toner on the intermediate transfer belt 5 and the pattern image for process control are scraped off from the intermediate transfer belt 5 by the intermediate transfer cleaning blade 13, and also pass through the collected toner conveyance path 14 e, and become a waste toner container 15. Is housed.

  The developing units 4a, 4b, 4c, and 4d used in each image forming unit of the image forming apparatus shown in FIG. 1 use, for example, a two-component developer that uses a two-component developer composed of toner particles and magnetic particles (referred to as carriers) as the developer. This is a developing type developing device. For example, as shown in FIG. 2, the developing device includes a developer carrier (for example, a developing roller) 16 that holds and rotates the developer, a developing container 26 that stores the developer, and a developing container. Developer conveying means (for example, conveying screws) 18 and 19 for conveying the developer while stirring the developer, and developer regulating means (regulating member) 17 for regulating the amount of the developer on the developer carrier 16 to a constant amount. Have. Further, the developing roller 16 as a developer carrying member is formed of a cylindrical developing sleeve having a surface shape described in an embodiment described later, and a plurality of magnetic poles are provided inside the developing sleeve 16 as magnetic field generating means 25. A magnetized magnet roller (or a plurality of magnets) is fixedly arranged.

  Next, replenishment of new toner to the developing devices 4a, 4b, 4c, and 4d of each image forming unit will be described. The new toner of each color filled in the toner cartridges of the toner replenishing devices 10a, 10b, 10c, and 10d is transferred to the toner hoppers 11a, 11b, 11c, and 11d on the rear side of the machine body by the toner replenishing devices 10a, 10b, 10c, and 10d. To be replenished. The toner stored in the toner hoppers 11a, 11b, 11c, and 11d is determined to have a low toner concentration in the developing device by the toner concentration detecting means (the toner concentration detecting sensor indicated by reference numeral 21 in FIG. 2) in the developing device. The toner replenishing screw (reference numeral 22 in FIG. 2) in the toner hopper is rotated, and an appropriate amount of toner is supplied from the toner hopper through the supply port (reference numeral 23 in FIG. 2) to each developing device 4a, 4b, 4c, 4d. To supply. The toner remaining amount detection of the toner cartridges of the toner replenishing devices 10a, 10b, 10c, and 10d is performed by supplying a toner presence / absence sensor (not shown) in the toner hopper and detecting the toner absence. The apparatus 10a, 10b, 10c, 10d is requested to supply toner. If the presence of toner is not detected even if requested for a predetermined time, it is determined that there is no toner, and a “no toner” warning is displayed on a display unit of an operation panel (not shown).

Next, FIG. 2 is a schematic cross-sectional view showing a configuration example of a process cartridge used in the image forming unit of the image forming apparatus shown in FIG. 1, and the configuration of the four image forming units is the same.
The image forming unit shown in FIG. 2 includes a photosensitive member 1, a developing unit (developing device) 4, a charging unit 2 (charging roller in this embodiment), and a cleaning unit 9 (cleaning blade in this embodiment) in one cartridge. The process cartridge is configured to be integrally supported. The developing unit 4 includes a developing roller 16 that forms a toner visualized image on a latent image on the photosensitive member optically formed on the photosensitive member 1 by writing means (only writing light 3 ′ is shown). On the upstream side of the developing area of the developing roller 16, a regulating member 17 (hereinafter referred to as a developing doctor 17) for regulating the amount of developer on the developing roller to a certain amount is provided. A two-component developer in which toner particles and magnetic particles (carriers) are mixed is stored in a developing container 26 of the developing device, and the developer contains two transport screws (a first transport screw 18 and a second transport screw). It is circulated while being stirred and mixed in accordance with 19). In addition, the above-described toner concentration sensor 21 is disposed below the second conveying screw 19, and the toner concentration in the developing container 26 is measured at any time and controlled so as to be within an appropriate value. The replenishment toner from the toner replenishing device is temporarily stored in the sub hopper (not shown), and converted to a predetermined conversion formula when the toner concentration sensor 21 detects that the toner concentration value is low. The toner replenishing screw 22 is rotated for a given time to replenish an appropriate amount of toner to the developing toner supply port 23. Further, an inlet seal 20 for preventing toner scattering from the developing nip portion is disposed on the right side of the developing doctor 17.

  The developing doctor 17 will be supplemented a little by using this sectional view (FIG. 2). The developing doctor of this embodiment is composed of two parts: a developing doctor base 17 made of a nonmagnetic member and a developing doctor auxiliary 24 made of a magnetic member. The developing doctor base 17 has a role of regulating the amount of developer on the developing roller 16 to a certain fixed amount, and receives the developer pressure at the doctor when regulating the developer. In general, a certain thickness (about 1.5 to 2 mm) and a straightness of about 0.05 mm at the tip are required. Further, the developing doctor auxiliary 24 has a role of supplementing the charging of the toner conveyed to the developing area, and is usually constituted by a sheet metal (about 0.2 mm) that is considerably thinner than the developing doctor mother body 17. The positional relationship between the two parts needs to be maintained with high accuracy in order to make the toner charging property uniform in the longitudinal direction, so that the distance from the developing roller is made constant by integration by spot welding or caulking. I am doing so. In this embodiment, the case where the developing doctor is below the center of the developing roller is described.

  Next, FIG. 3 and FIG. 4 explain a schematic configuration of a part of the developing device 4. FIG. 3 is a perspective view showing the overall appearance. FIG. 3 is a cross-sectional view of FIG. 2 viewed from the upper left direction. 4 is a view in which the upper case 28 is removed from the developing device 4, and the developing roller 16, the first conveying screw 18, and the second conveying screw 19 are visible. The developer accumulates in the transport screw portion and circulates between the first transport screw 18 and the second transport screw 19. The case top 28 shown in FIG. 3 has a preset space 28 ′ in which a developer is placed when the unit is shipped. This is a mechanism to prevent developer leakage during transportation by putting developer in this part during transportation as a unit and sealing it with a removable seal member. It is something to be made. 3 and 4 are provided integrally with the process cartridge shown in FIG. 2, but may be configured independently.

  As described above, the image forming apparatus according to the present invention and the developing device and the process cartridge installed in the image forming apparatus have been described. However, in the present invention, the developer carrying member (developing) constituting the developing device 4 is described. Roller) 16. A specific example of the developer carrier (developing roller) 16 will be described below.

  FIG. 5 shows an example of a developer carrier (developing roller) 16 having an iris-shaped groove pattern. FIG. 6 is a diagram showing the surface shape of the developing sleeve constituting the developing roller 16 developed on a plane. As shown in FIGS. 5 and 6, the developing roller (developing sleeve) 16 according to the present invention includes a plurality of grooves formed at an acute angle with respect to the rotation center axis direction (thrust direction) 33, and a thrust direction. A pattern of iris-shaped grooves 32 formed on the surface is formed by crossing a plurality of grooves formed at an acute angle on the opposite side to 33.

  FIG. 7 is an enlarged view of a part of the developed shape of FIG. The portion surrounded by the groove of the iris-shaped groove pattern on the sleeve surface of the developing roller 16 is a rhombus-shaped convex portion, and the gray-shaped rhombus portion 31 in FIG. 7 is a convex portion in which no groove is formed. The portion of the broken line 32 that intersects diagonally is an iris-shaped groove. Also, the center alternate long and short dash line 33 indicates the rotation center axis (thrust direction) of the developing roller. As described above, the developing roller 16 having the iris-shaped groove 32 is an aggregate of rhombus-shaped convex portions 31. As a problem with the conventional iris shape, when the cross section of the roller is expressed in a linear direction, it is a combination of short and convex cycles, and is weak in terms of strength. Since the developing roller receives a load in the doctor portion for regulating the developer and the developing region (to the photosensitive member), the developing roller requires a certain degree of strength in the longitudinal direction (axial direction (thrust direction)) 33. If the strength is insufficient, the central portion of the developing roller in the longitudinal direction (thrust direction) 33 is bent. The gap (development gap) between the surface of the developing roller and the surface of the photosensitive member is widened, and the developing ability (density) at the center is lowered. To compensate for this, if the amount of developer to be carried is increased to increase the density at the center, it is necessary to increase the density at the edge, resulting in increased toner consumption. Further, in order to prevent the developing roller from being bent, it is necessary to increase the thickness of the developing sleeve or to change the material in order to increase the strength of the developing roller.

Therefore, the configuration of the developing roller of the present invention for solving the above problems will be described.
In the present invention, in order to solve the above problem, one end point in the thrust direction of the rhombus-shaped convex portion and one end point in the thrust direction of the rhombus-shaped convex portion adjacent to the rhombus-shaped convex portion are the thrust direction. It is set as the structure which provided the part which is connected by the convex part extended in, and does not comprise the groove | channel.

FIG. 8 shows the developing roller of the first embodiment of the present invention, and is an enlarged view of a part of the developed shape of the roller surface as in FIG. The broken line ellipse part 34 in FIG. 8 is a feature of the first embodiment. Details will be described with reference to FIG. 9 in which the ellipse part 35 indicated by a two-dot chain line is enlarged. This is an enlarged view of some of the two adjacent diamond-shaped convex portions.
As shown in FIG. 9, in this embodiment, one end point 38 in the thrust direction of the rhombus-shaped convex portion 36 and one end point 39 in the thrust direction of the rhombus-shaped convex portion 37 adjacent to the rhombus-shaped convex portion 36. (To be more specific, the longitudinal direction of the developing roller is placed in the left-right direction of the paper surface, and the right end point 38 when the left rhombus-shaped protrusion 36 is viewed from the front and the adjacent rhombus-shaped protrusion 37 are The left end point 39) is connected by a convex portion 40 extending in the thrust direction 33 to provide a portion not forming a groove. By adopting such a shape, it is possible to maintain strength with respect to the longitudinal direction (thrust direction) 33 of the developing roller.

Next, FIG. 10 is a view showing a second embodiment of the present invention, and is an enlarged view of a part of the developed shape of the roller surface as in FIG.
In this embodiment, as shown in FIG. 9, the thrust direction of the end point 38 in the thrust direction 33 of the rhombic convex portion 36 of the iris-shaped groove pattern and the rhomboid convex portion 37 adjacent to the rhomboid shape. A portion where one end point 39 of 33 is connected by a convex portion 40 extending in the thrust direction 33 and does not form a groove is provided continuously in the thrust direction 33.
That is, in the embodiment of FIG. 10, the portion that does not form the groove shape of the portion connecting the longitudinal direction (thrust direction) 33 of the adjacent rhombus-shaped convex portions 31 of the first embodiment (the convex portion as in FIG. 9). 40) is applied to all of the longitudinal direction (thrust direction) 33 of the developing roller. A broken-line ellipse 41 in the figure becomes the portion (portion connected by the convex portion 40 as in FIG. 9). By adopting such a shape, it is possible to efficiently maintain the strength in the continuous portion in the thrust direction 33 on the circumference of the developing roller. Therefore, it is possible to efficiently reduce the thickness of the developing sleeve constituting the developing roller, and to reduce the material.

Next, FIG. 11 is a view showing a third embodiment of the present invention, and is an enlarged view of a part of the developed shape of the roller surface as in FIGS.
In this embodiment, as in FIG. 10, one end point in the thrust direction 33 of the rhombus-shaped convex portion 31 of the iris-shaped groove pattern and one end point in the thrust direction 33 of the rhombus-shaped convex portion adjacent to the rhombus shape. Are connected by a projection 40 extending in the thrust direction 33 to form a groove (a portion connected by the projection 40 as in FIG. 9) continuously in the thrust direction 33. As shown in FIG. 11, the shape continuously provided in the direction is configured to be provided on the entire surface of the roller.
That is, in the embodiment of FIG. 11, the portion that does not form the groove shape of the portion connecting the longitudinal direction (thrust direction) 33 of the adjacent rhombus-shaped convex portions 31 of the first embodiment (the convex portion as in FIG. 9). 40) is applied to the entire longitudinal direction (thrust direction) of the surface of the developing roller. By adopting such a shape, the strength in the longitudinal direction (thrust direction) 33 can be maximally enhanced at every point on the circumference of the developing roller, and the effect of reducing the material can be maximized. It becomes possible.

  In addition, the manufacturing method of the surface shape of the developing roller (developing sleeve) shown in the first to third embodiments can be easily created by an etching method.

In the developing device 4 according to the present invention, the developing roller 16 of any one of the first to third embodiments is used as the developing roller 16, so that the strength of the developing roller 16 in the thrust direction (longitudinal direction) 33 is increased. The bending of the central portion can be reduced, the difference in developing ability between the central portion and the end portion in the longitudinal direction can be reduced, and stable development can be performed.
In the developing device 4 of the present invention, even when a two-component developer composed of toner particles and magnetic particles is used as the developer and the developing roller 16 is a cylindrical developing sleeve, the developing sleeve is in the thrust direction (longitudinal direction). The strength of the developing sleeve can be increased, stable development can be performed, and the developing sleeve can be thinned.

In the process cartridge having the configuration shown in FIG. 2, the developing device 4 includes the developing device using the developing roller of any one of the first to third embodiments described above, so that stable development can be performed. And a highly reliable process cartridge can be provided.
In the image forming apparatus of the present invention, since the developing device 4 or the process cartridge is provided in the image forming unit, stable development can be performed, and high-quality and highly reliable image formation can be performed. It becomes possible.
In addition, as shown in FIG. 1, by providing the above-described developing device 4 or process cartridge in a plurality of image forming units, each image forming unit can stably develop each color, and high image quality, A highly reliable color image can be formed.

Next, toner that is preferably used in the image forming apparatus of the present invention provided with the developing device 4 using the developing roller having the above surface shape or the process cartridge will be described.
In order to reproduce minute dots having a resolution of 600 dpi (dots / inch) or more, the volume average particle diameter of the toner is preferably 3 to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.40. The closer (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

The toner shape factor SF-1 is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180. 12 and 13 are diagrams schematically showing the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2. As shown in FIG. 12, the shape factor SF-1 indicates the ratio of the roundness of the toner shape, and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting toner onto a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.

As shown in FIG. 13, the shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). This is a value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner onto the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) ² / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.

Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.) and introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) for analysis. And calculated.
When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photosensitive member becomes a point contact, so that the adsorbing force between the toners becomes weak, and thus the fluidity becomes high. The attracting power with the body also becomes weaker, and the transfer rate becomes higher. Further, if any of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration example of a process cartridge used in an image forming unit of the image forming apparatus illustrated in FIG. 1. 1 is a perspective view showing an overall appearance of a developing device according to the present invention. FIG. 4 is a perspective view showing a state in which the case of the developing device shown in FIG. 3 is removed. FIG. 5 is a perspective view showing an example of a developing carrier (developing roller) having a iris-shaped groove pattern. FIG. 6 is a diagram showing a surface shape of a developing sleeve constituting the developing roller shown in FIG. FIG. 7 is an enlarged view of a part of the surface shape of the developing sleeve of FIG. 6. FIG. 8 shows the developing roller according to the first embodiment of the present invention, and is an enlarged view of a part of the developed shape of the roller surface as in FIG. 7. It is the figure which expanded and showed the two diamond-shaped convex part which the ellipse part shown with the dashed-two dotted line of FIG. 8 adjoins. It is a figure which shows the 2nd Example of this invention, and is the figure which expanded and looked at part of the expansion | deployment shape of the roller surface similarly to FIG. It is a figure which shows the 3rd Example of this invention, and is the figure which expanded and looked at a part of the expansion | deployment shape of the roller surface similarly to FIG. 8, FIG. FIG. 4 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-1. FIG. 6 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-2.

Explanation of symbols

1 (1a, 1b, 1c, 1d): photoconductor (image carrier)
2 (2a, 2b, 2c, 2d): charging means 3 (3a, 3b, 3c, 3d): optical writing means (latent image forming means)
4 (4a, 4b, 4c, 4d): developing device (developing means)
5: Intermediate transfer belt (intermediate transfer member)
6: Registration roller pair 7: Secondary transfer unit 8: Fixing unit 9 (9a, 9b, 9c, 9d): Cleaning unit 16: Developing roller (developer carrier)
17: Development doctor (developer regulation means)
18, 19: Conveying screw (developer conveying means)
26: Development container 31, 36, 37: Diamond-shaped convex part 32: Iris-shaped groove 33: Center axis of rotation (thrust direction)
40: Convex portion extending in the thrust direction

Claims (10)

A plurality of grooves formed at an acute angle with respect to the rotational axis direction (hereinafter referred to as a thrust direction) and a plurality of grooves formed at an acute angle opposite to the thrust direction. In the developer carrying member that has an iris-shaped groove pattern formed on the surface and rotates while holding the developer by the iris-shaped groove pattern,
A portion of the surface surrounded by the groove of the iris-shaped groove pattern is a rhombus-shaped convex portion, and one end point in the thrust direction of the rhomboid-shaped convex portion is adjacent to the rhombus-shaped convex portion. A developer carrying member, characterized in that a rhombus-shaped convex portion is connected to a thrust end portion in the thrust direction by a convex portion extending in the thrust direction so as not to form a groove. The developer carrier according to claim 1,
One end point in the thrust direction of the rhomboid convex portion of the iris-shaped groove pattern is connected to one end point in the thrust direction of the rhomboid convex portion adjacent to the rhombus shape by a convex portion extending in the thrust direction. The developer carrying member according to claim 1, wherein a portion not forming a groove is provided continuously in the thrust direction. The developer carrier according to claim 1 or 2,
One end point in the thrust direction of the rhombic convex portion of the iris-shaped groove pattern and one end point in the thrust direction of the rhomboid shape adjacent to the rhombus shape are connected by the convex portion extending in the thrust direction to form a groove. The developer carrying member, wherein a portion that is not provided is provided continuously in the thrust direction, and a shape provided continuously in the thrust direction is provided on the entire surface. A developer carrying member that holds and rotates the developer, a developer container that contains the developer, a developer carrying means that carries the developer contained in the developer container while stirring, and the developer carrying In a developing device having developer regulating means for regulating the amount of developer on the body to a constant amount,
A developing device using the developer carrying member according to any one of claims 1 to 3 as the developer carrying member. The developing device according to claim 4.
The developer is a two-component developer composed of toner particles and magnetic particles, and the developer carrier is a cylindrical developing sleeve having the surface shape, and a magnetic field generating means is provided inside the developing sleeve. A developing device. In a process cartridge that integrally supports at least one unit selected from an image carrier, a developing unit, a charging unit, and a cleaning unit, and is detachably mounted on an image forming apparatus main body.
6. A process cartridge comprising the developing device according to claim 4 or 5 as the developing means. In an image forming apparatus including an image forming unit that forms a latent image on an image carrier and develops the latent image to form a visible image.
An image forming apparatus comprising the developing device according to claim 4 or the process cartridge according to claim 6 in the image forming unit. In an image forming apparatus including a plurality of image forming units that form a latent image on an image carrier and develop the latent image to form a visible image.
An image forming apparatus comprising the developing device according to claim 4 or the process cartridge according to claim 6 in the plurality of image forming units. The image forming apparatus according to claim 7 or 8, wherein
The toner used in the developing device or the process cartridge has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of volume average particle diameter (Dv) to number average particle diameter (Dn) of 1.00. An image forming apparatus in the range of ˜1.40. The image forming apparatus according to claim 7 or 8, wherein
The toner used in the developing device or the process cartridge is an image forming apparatus having a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180.

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