JP2010243886A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device for improving the flying property while keeping high charging property, and an image forming apparatus including the developing device. <P>SOLUTION: The developing device includes a developing roller, wherein the surface of the developing device includes a spiral groove tilting at a predetermined angle with respect to the axial direction and circumferential direction, and the groove has irregularity carrying an external additive. Since the external additive is carried by the irregularity of the groove, a mirror image force applied to toner stacked on it is reduced, and the flying property is improved while high charging property is kept. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrophotographic developing device and an image forming apparatus including the same.

  In an image forming apparatus using a non-magnetic one-component toner, the toner is charged by friction charging on the developing roller. In order to efficiently generate triboelectric charging, Japanese Patent Application Laid-Open No. 2001-66876 discloses that the developing roller is blasted to give a predetermined surface roughness Rz to the developing roller surface, and the toner rubs the developing roller well. A developing roller that is in a ready state is disclosed.

  However, the recesses formed by the blasting process are not uniform in size, depth, shape, and arrangement. For this reason, since the toner that has entered the deep concave portion is not rolled, there is a possibility that the toner will not be charged well. Thus, filming may occur due to unevenness of the uneven portion on the surface of the developing roller. In addition, when the toner is not charged well, there is a problem that the toner may leak from the developing device and be scattered in the image forming apparatus or the image may be fogged.

  In order to improve the chargeability of the toner, Japanese Patent Application Laid-Open No. 2007-121947 discloses a developing roller in which grooves regularly arranged in a grid pattern are formed on the developing roller by rolling, and a method for manufacturing the same. Yes. It has been reported that the developing roller in which such a groove is formed by a rolling process has improved chargeability as compared with a developing roller having an irregular surface state such as blasting.

JP 2001-66876 A JP 2007-121947 A

  On the other hand, the developing roller in which the grooves arranged in a regular lattice pattern are formed by rolling process carries the toner in the grooves formed on the surface. Generally, a highly charged toner is attracted to the surface of the developing roller to form the first layer of the toner layer. The first-layer toner has a large mirror image force due to the short distance from the surface of the developing roller, and is difficult to fly to the photoreceptor side even when a developing bias is applied. On the other hand, the second layer toner has a lower image power than the first layer toner and has a high flying ability, but it tends to cause fog due to its low charge amount. As a result, the development amount by the developing roller tends to be low. In order to increase the development amount, it is necessary to increase the toner conveyance amount while suppressing the occurrence of fog. However, there is a trade-off relationship between the toner conveyance amount and the charge amount, which is a parameter for suppressing the occurrence of fogging. Even if the groove depth is increased to increase the toner conveyance amount, the amount of low-charge toner transferred from the second layer onward increases, so that the development amount does not increase. As described above, it is very difficult to increase the developing amount in the configuration of the conventional developing device.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device that solves the problems of the prior art and that can improve flying performance while maintaining high chargeability, and an image forming apparatus including the developing device.

  In the developing device of the present invention, in order to solve the above-described problems, a spiral groove portion inclined at a predetermined angle with respect to the axial direction and the circumferential direction is formed on the surface, and unevenness supporting an external additive is formed in the groove portion. It is characterized by comprising a developed developing roller. Since the external additive is carried on the concave and convex portions of the groove portion, it is possible to reduce the mirror image force applied to the first-layer toner laminated thereon, and to improve the flight property while maintaining high chargeability.

  The developing device of the present invention is characterized in that the external additive is a free external additive. The free external additive released from the toner is held on the irregularities of the groove to form a film of the free external additive, and the flying property can be improved while maintaining the high chargeability of the toner.

  In the developing device of the present invention, the free external additive is insulative and has a normal charging polarity opposite to the normal charging polarity of the toner. By making it insulative, the mirror image force applied to the toner is reduced, and by making it reversely chargeable to the toner, it becomes possible to prevent the toner from being reversely charged due to contact between the external additive and friction.

  In the developing device of the present invention, the surface roughness of the unevenness is larger than the average particle diameter of the external additive. The distance between the toner of the first layer and the surface of the developing roller can be maintained, and the image force applied to the toner can be reduced.

  Further, the developing device of the present invention is characterized in that the unevenness of the groove is formed by a die whose surface is blasted. Unevenness can be easily formed on the bottom of the groove.

  Further, the developing device of the present invention is characterized in that the groove is formed by rolling with a die having a smooth surface after rolling with a smooth surface die. Unevenness can be easily formed on the bottom of the groove.

  Further, the developing device of the present invention is characterized in that the unevenness of the groove is formed by blasting after plating the surface. It is possible to easily form irregularities on the bottom surface of the groove.

  The image forming apparatus of the present invention includes a latent image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image with toner and develops the toner image on the latent image carrier, And a transfer device that transfers the toner image of the latent image carrier to a transfer medium, wherein the developing device is any one of the developing devices described above. Since the external additive is carried on the concave and convex portions of the groove portion, it is possible to reduce the mirror image force applied to the first-layer toner laminated thereon, and to improve the flight property while maintaining high chargeability.

1 is a diagram schematically showing an example of an embodiment of an image forming apparatus of the present invention. It is a schematic diagram which shows an example of the image development unit of this invention. FIG. 4 is a partial view of the developing unit of the present invention. It is a figure which shows an example of the image development roller of this invention, and the partial enlarged view of the surface. Shows the state of toner in the groove of the developed developing roller It is groove part sectional drawing of the developing roller which is rolled. It is a figure which shows the relationship between the average particle diameter of an external additive, and the surface roughness of an unevenness | corrugation. It is a figure which shows the relationship between the average particle diameter of an external additive, and the surface roughness of an unevenness | corrugation. It is a figure which shows the relationship between the average particle diameter of an external additive, and the surface roughness of an unevenness | corrugation. It is a figure which shows an example of the rolling apparatus which uses the developing roller of this invention for a rolling process. It is a figure which shows an example of the shape of the blade of the die | dye of a rolling apparatus. It is a figure which shows an example of the rolling apparatus which uses the developing roller of this invention for a rolling process. It is a figure which shows an example of the shape of the blade of the die | dye of a rolling apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing an example of an embodiment of an image forming apparatus of the present invention.

  As shown in FIG. 1, the image forming apparatus 10 includes four image forming stations 15 (Y, M, C, and K), an intermediate transfer belt 70, and a secondary transfer unit 80, and further includes a fixing unit 90 and a liquid crystal. The display unit 95 includes a panel, and a control unit 100 that controls these units and controls the operation of the image forming apparatus.

  The image forming station 15 (Y, M, C, K) has a function of forming an image with toners of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Since the configuration of the image forming station 15 (Y, M, C, K) is the same, the image forming station 15Y will be described below.

  As shown in FIG. 1, the image forming station 15Y includes a charging unit 30Y, an exposure unit 40Y, a developing unit 50Y, and a primary transfer unit along the rotation direction of a photoconductor 20Y as an example of an image carrier. .

  The photoreceptor 20Y has a cylindrical base material and a photosensitive layer formed on the outer peripheral surface thereof, and can rotate around a central axis. In the present embodiment, the photoreceptor 20Y rotates clockwise as indicated by an arrow. To do.

  The charging unit 30Y is a device for charging the photoconductor 20Y. From the exposure unit 40Y, a latent image is formed on the charged photoreceptor 20Y by irradiating a laser.

  The exposure unit 40Y has a semiconductor laser, a polygon mirror, an F-θ lens, and the like, and is charged with a modulated laser based on an image signal input from a host computer (not shown) such as a personal computer or a word processor. Irradiate onto the photoconductor 20Y.

  The development unit 50Y is a device for developing the latent image formed on the photoreceptor 20Y using yellow (Y) toner. In the developing unit 50Y, a developing roller 51Y and a supply roller 52Y are disposed in a developing chamber to which toner is supplied from a replaceable toner cartridge. A regulating blade 53Y contacts the developing roller 51Y to thin the toner on the developing roller 51Y. Stratify.

  In the primary transfer unit, a primary transfer bias is applied by the primary transfer roller 65Y in the primary transfer portion B1, and the yellow toner image formed on the photoreceptor 20Y is transferred to the intermediate transfer belt 70. When the four color toners are sequentially transferred in the primary transfer portions B 1, B 2, B 3 and B 4, a full color toner image is formed on the intermediate transfer belt 70.

  The intermediate transfer belt 70 is an endless belt stretched around a belt driving roller 71a and a driven roller 71b, and is rotationally driven while being in contact with the photoreceptor 20 (Y, M, C, K).

  The secondary transfer unit 80 is a device for transferring a single color toner image or a full color toner image formed on the intermediate transfer belt 70 onto a transfer material such as paper, film, or cloth.

  The fixing unit 90 includes a fixing roller 90a and a pressure roller 90b, and is a device for fusing a single color toner image or a full color toner image transferred onto a transfer material to the transfer material to obtain a permanent image.

  Next, the operation of the image forming apparatus 10 configured as described above will be described. First, when an image signal and a control signal from a host computer (not shown) are input to the main controller of the image forming apparatus via an interface, the photoconductor 20Y and the developing unit are controlled by a unit controller based on a command from the main controller. The developing roller 51Y provided in 50Y, the intermediate transfer belt 70, and the like rotate. The photoconductor 20Y is sequentially charged by the charging unit 30Y at the charging position while rotating.

  The charged area of the photoconductor 20Y reaches the exposure position as the photoconductor 20Y rotates, and a latent image corresponding to yellow Y image information is formed in the area by the exposure unit 40Y.

  The latent image formed on the photoreceptor 20Y reaches the development position as the photoreceptor 20Y rotates, and is developed by the development unit 50Y. Thereby, a toner image is formed on the photoreceptor 20Y.

  The toner image formed on the photoconductor 20Y reaches the position of the primary transfer portion B1 as the photoconductor 20Y rotates, and is transferred to the intermediate transfer belt 70 by the primary transfer unit. At this time, in the primary transfer unit, a primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied from the primary transfer roller 65Y. As a result, the four color toner images formed on the respective photoreceptors 20 (Y, M, C, K) are transferred to overlap the intermediate transfer belt 70, and a full color toner image is formed on the intermediate transfer belt 70. Is done.

  The intermediate transfer belt 70 is driven by transmitting a driving force from a belt driving means such as a motor via a belt driving roller 71a.

  The full color toner image formed on the intermediate transfer belt 70 is transferred to a transfer material such as paper by the secondary transfer unit 80. Such a transfer material is conveyed from the paper feed tray to the secondary transfer unit 80 via the paper feed roller 94a and the registration roller 94b.

  The full-color toner image transferred to the transfer material is heated and pressed by the fixing unit 90 and fused to the transfer material. After passing through the fixing unit 90, the paper is discharged by a paper discharge roller 94c.

  On the other hand, the photosensitive member 20 (Y, M, C, K) is neutralized by a neutralizing unit (not shown) after passing through the primary transfer portions B1, B2, B3, B4 to form the next latent image. To prepare for charging. An intermediate transfer belt cleaning device (not shown) is installed on the driven roller 71b side of the intermediate transfer belt 70 after the secondary transfer, and cleans the intermediate transfer belt 70 after the secondary transfer.

  FIG. 2 is a schematic diagram showing an example of the developing unit 50Y of the present invention, and FIG. 3 is a partial view of the developing unit 50Y of this example.

  The developing unit 50Y includes a developing roller 51Y that conveys the toner T to the photoreceptor 20Y, a supply roller 52Y that is pressed against the developing roller 51Y to supply the toner T, and a toner T that is pressed against the developing roller 51Y and conveyed to the photoreceptor 20Y. A regulating blade 53Y for regulating, a toner agitating / conveying member 54Y for agitating and conveying the toner T, a toner receiving member 55Y for receiving the toner T conveyed by the toner agitating / conveying member 54Y and guiding it toward the supply roller 52Y, and a developing roller 51Y is provided with a seal member 56Y for preventing toner leakage while abutting in the direction for collecting the toner T remaining after development, and a developing chamber 57Y for accommodating the toner T.

  The developing roller 51Y is formed in a cylindrical shape with a conductive material such as a metal such as copper, iron, aluminum, stainless steel, or an alloy. The supply roller 52Y is formed in a cylindrical shape by an elastic material such as foamed urethane rubber or silicon rubber. By rotating the developing roller 51Y and the supply roller 52Y in contact with each other, the toner T is supplied onto the developing roller 51Y, and a toner layer having a predetermined thickness is formed on the developing roller 51Y. The regulating blade 53Y comes into contact with the developing roller 51Y supplied with the toner T, and regulates the toner layer thickness on the developing roller 51Y. The regulating blade 53Y also functions to prevent the toner T from leaking from the developing chamber 57Y. The toner is charged by frictional charging on the developing roller 51Y.

  As shown in FIG. 3, spacers 58Y are fixed to both ends of the developing roller 51Y. When these spacers 58Y are pressed against the image non-carrying surface of the photoreceptor 20Y, a developing gap g is formed between the toner carrying surface of the developing roller 51Y and the image carrying surface of the photoreceptor 20Y facing the toner carrying surface. Is formed.

  The developing gap g is adjusted to a desired size by appropriately selecting the thickness of the spacer 58Y. As a result, this developing device performs non-magnetic one-component developer non-contact jumping development using toner T which is a non-magnetic one-component developer. In this case, in this example, the photosensitive member 20Y is set to rotate clockwise and the developing roller 51Y and the supply roller 52Y are both rotated counterclockwise. The peripheral speed of the photoconductor 20Y and the peripheral speed of the spacer 58Y on the developing roller 51Y are set to be the same or substantially the same. In the present embodiment, the non-contact development method has been described, but a contact development method may be used.

  FIG. 4 is a view showing an example of the developing roller of the present invention and a partially enlarged view of the surface thereof.

  In order to improve toner transportability and toner chargeability, a first inclined groove 51a that is spirally continuous on the surface of the developing roller 51Y with a predetermined angle with respect to the axial direction and the circumferential direction, and a first inclination The groove 51a and the second inclined groove 51b that is continuous in a spiral shape that is inclined in the axial direction and the circumferential direction in the opposite direction are formed to intersect. Further, a quadrangular convex portion 51c having an inclined side surface 51d surrounded by the first inclined groove 51a and the second inclined groove 51b is formed. The developing roller 51Y of the present invention employs a regulation system that transports toner through the groove portions of the first inclined groove 51a and the second inclined groove 51b formed on the surface thereof. Since the developing roller 51Y is made of a conductive material such as a metal such as copper, iron, aluminum, and stainless steel or an alloy, a mirror image force acts on the charged toner conveyed in the groove and is stable. The toner is conveyed to the development nip.

  In addition, when a small particle size toner having a volume average particle size of 5 μm or less is used as the toner, the image quality can be improved, and the small particle size toner has higher chargeability than a toner having a large particle size. It is suitable for a regulation system in which toner is mainly conveyed in a groove. In addition, the surface of the developing roller 51Y may be subjected to nickel plating, chrome plating, or the like as necessary. In addition, a toner having an average circularity of 0.95 to 0.99, preferably 0.972 to 0.983 may be used. As a result, the charge amount can be stabilized and the transportability can be improved. As a method of adjusting the circularity of the toner, in the emulsion polymerization method, the circularity can be freely changed by controlling the temperature and time during the aggregation process of the secondary particles, and the range is from 0.94 to 1.00. And can. In the suspension polymerization method, a true spherical toner can be produced, and the circularity is in the range of 0.98 to 1.00. In order to set the average circularity to 0.95 to 0.99, it can be appropriately adjusted by heat-deforming at a temperature equal to or higher than the Tg temperature of the toner. In this embodiment, a toner having a negative regular charging polarity is used. In such a toner, negatively chargeable mother particles are adjusted, and external additives such as positively chargeable silica fine particles, titanium oxide fine particles, and resin beads are added to the mother particles to control charge amount or fluidity. Is going.

  FIG. 5 shows the state of toner in the first and second inclined grooves 51a and 51b of the developed developing roller 51Y. In general, since a toner with a high charge amount is attracted to the surface of the developing roller, the toner of the first layer that contacts the bottom surfaces of the first and second inclined grooves 51a and 51b has a high charge amount, but has a conductive property. It is difficult for the developing roller 51Y to fly due to a large mirror image force. On the other hand, the second layer toner in contact with the first layer toner is easy to fly because of low mirror image force with the conductive developing roller as compared with the first layer toner, but fog is generated due to the low charge amount. To do.

  FIG. 6 is a cross-sectional view of the groove portion of the developing roller 51Y formed by a rolling process that solves the above problem.

  As shown in FIG. 6, irregularities 51f are formed on the bottom surfaces of the first and second inclined grooves 51a and 51b of the developing roller 51Y. The external additive is conveyed and held on the irregularities 51f, and the first layer toner and the second layer toner are laminated on the external additive. Since the external additive held on the unevenness 51f can reduce the mirror image force applied to the first-layer toner layered thereon and increase the flying property while maintaining a high charge amount, the development amount can be improved.

  FIG. 7 is a diagram illustrating a case where the average particle size Rx of the external additive is increased with respect to the surface roughness Rz of the unevenness 51f formed on the bottom surfaces of the first and second inclined grooves 51a and 51b. Since the average particle diameter r of the external additive is larger than the surface roughness Rz of the unevenness 51f, the distance between the first-layer toner and the groove bottom surface can be maintained, so that the mirror image force applied to the first-layer toner is reduced and the high charge amount is increased. To improve flight performance.

  FIG. 8 is a diagram showing a case where the average particle diameter r of the external additive is smaller than the surface roughness Rz of the unevenness 51f formed on the bottom surfaces of the first and second inclined grooves 51a and 51b. Since the average particle diameter r of the external additive is smaller than the surface roughness Rz of the unevenness 51f, the distance between the first-layer toner and the groove bottom cannot be maintained, and the mirror image force applied to the first-layer toner cannot be reduced. , Flying ability can not be improved.

  FIG. 9 is a diagram illustrating a case where the surface roughness Rz of the unevenness 51f formed on the bottom surfaces of the first and second inclined grooves 51a and 51b is too small with respect to the average particle diameter r of the external additive. Since the surface roughness Rz of the unevenness 51f is too small with respect to the average particle diameter r of the external additive, the external additive cannot be retained. Therefore, the surface roughness Rz of the irregularities 51f formed on the bottom surfaces of the first and second inclined grooves 51a and 51b and the average particle size r of the external additive are r> Rz under the condition that the external additive is retained. It is a relationship.

  A free external additive is desirable as the external additive that is held by the irregularities 51f on the bottom surfaces of the first and second inclined grooves 51a and 51b of the developing roller 51Y. This is because by using the free external additive, the free external additive is released from the toner and conveyed to the unevenness 51f so that a film of the free external additive is easily formed. External additives are added at the final stage of external addition in order to increase the liberation rate of other external additives. In addition, the external additive strength (time and number of stirring) of the external additive is weaker than other external additives. To do.

  As a condition of the free external additive, when it is insulative and the normal charging polarity of the toner is negative, the positive normal charging polarity is reversed. By making it insulative, the mirror image force applied to the first layer of toner can be reduced by the free external additive held on the unevenness 51f. Further, by setting the positive normal charging polarity opposite to the negative normal charging polarity toner, the toner is prevented from being positively charged due to contact between the external additive and friction.

  In the present embodiment, resin beads manufactured by Soken Kagaku Co., Ltd. (MP1000, average particle size 400 nm) were used as external additives. Alternatively, a free external additive film may be formed by previously applying the free external additive to the irregularities 51f on the bottom surfaces of the first and second inclined grooves 51a and 51b.

The specifications of the developing roller 51Y and the supply roller 52Y used in this embodiment are as follows.
Groove depth of developing roller: 10um
Contact direction between the supply roller and the developing roller: With Amount of biting of the supply roller into the developing roller: 0.95 mm
Supply roller material: Bridgestone, EPT51
Supply roller hardness: 70-80
Average particle diameter of toner: 4um

  FIG. 10 shows a rolling device used in the first embodiment for rolling a developing roller 51Y having irregularities 51f formed on the groove bottom surface.

  The rolling device 200 used for the rolling process of the first embodiment includes a first die 201 including a first inclined blade 201a inclined in the axial direction and the circumferential direction for forming the first inclined groove 51a in the developing roller 51Y. A second die 202 having a second inclined blade 202a inclined in the axial direction and the circumferential direction opposite to the first inclined blade 201a for forming the second inclined groove 51b in the developing roller 51Y, and the first die 201 and a guide table 203 disposed below the second die 202. As shown in FIG. 11, the surface of the 1st inclination blade 201a and the 2nd inclination blade 202a has the unevenness | corrugation processed by blasting.

  The rolling device 200 is arranged between a first die 201 and a second die 202 that are arranged at opposite positions and are rotating clockwise as indicated by an arrow, and a guide table 203 (here, unrolled processing). The developing roller 51Y) is conveyed and rolled. During the rolling process, the first die 201 and the second die 202 are applied with a processing pressure in a direction in which the unprocessed developing roller 51Y is pressed. The unprocessed developing roller 51Y is rolled by rotating in the counterclockwise direction opposite to the rotation direction of the first die 201 and the second die 202.

  The first die 201 and the second die 201 have a first inclined blade 201a and a second inclined blade 202a, respectively, whose surfaces for forming the first inclined groove 51a and the second inclined groove 51b are blasted. Is provided. The first inclined blades 201a and the second inclined blades 202a are inclined with respect to the axial direction and the circumferential direction intersecting the surface of the non-rolling processing developing roller 51Y, and the first inclined grooves 51a having irregularities 51f formed on the bottom surface. A headed quadrangular frustum-shaped convex portion 51c having a second inclined groove 51b and an inclined side surface 51d is formed.

  FIG. 12 shows a rolling device used in the first step of the second embodiment for rolling the developing roller 51Y having irregularities 51f formed on the groove bottom surface.

  The rolling device 200 ′ used in the first step of the rolling process of the second embodiment includes a first inclined blade 201a ′ inclined in the axial direction and the circumferential direction for forming the first inclined groove 51a in the developing roller 51Y. The first die 201 ′ provided and the second inclined blade 202a ′ inclined in the axial direction and the circumferential direction opposite to the first inclined blade 201a ′ for forming the second inclined groove 51b in the developing roller 51Y. A second die 202 ′, a first die 201 ′, and a guide base 203 ′ disposed below the second die 202 ′ are provided. As shown in FIG. 13, the surfaces of the first inclined blade 201a and the second inclined blade 202a are formed smoothly.

  The rolling device 200 ′ is arranged between a first die 201 ′ and a second die 202 ′ that are arranged at opposite positions and rotated clockwise as indicated by an arrow, and a guide table 203 ′ (here, The non-rolling processing developing roller 51Y) is conveyed and rolled. During the rolling process, the first die 201 ′ and the second die 202 ′ are applied with a processing pressure in a direction in which the unprocessed developing roller 51 </ b> Y is pressed. The unprocessed developing roller 51Y is rotated and rotated in the counterclockwise direction opposite to the rotation direction of the first die 201 'and the second die 202'.

  The first die 201 ′ and the second die 202 ′ have a first inclined blade 201a ′ and a second inclined blade 202a ′ having smooth surfaces for forming the first inclined groove 51a and the second inclined groove 51b described above. , Each is provided. The first inclined blades 201a ′ and the second inclined blades 202a ′ are inclined with respect to the axial direction and the circumferential direction intersecting the surface of the non-rolled processing developing roller 51Y, and the first inclined grooves 51a and second having a smooth bottom surface. A headed quadrangular frustum-shaped convex portion 51c having an inclined groove 51b and an inclined side surface 51d is formed.

  In the second step of the rolling process of the second embodiment, the first die 201 including the first inclined blade 201a and the second inclined blade 202a, in which the surface shown in FIG. Rolling is performed in the same manner as in the first embodiment by the rolling device 200 shown in FIG. Concavities and convexities 51f are formed on the smooth bottom surface formed in the first step.

  In the first step of the third embodiment in which the developing roller 51Y having the irregularities 51f formed on the bottom surface of the groove is rolled, the bottom surface of the groove is smooth by the rolling device 200 ′ used in the first step of the second embodiment. A first inclined groove 51a and a second inclined groove 51b are formed.

  In the second step of the third embodiment, the first inclined groove 51a and the second inclined groove 51b formed in the first step and having a smooth groove bottom surface are plated, and then the unevenness 51f is formed by blasting and processing. .

  10: image forming apparatus, 15 (Y, M, C, K): image forming station, 20 (Y, M, C, K): photoconductor, 30 (Y, M, C, K): charging unit, 40 (Y, M, C, K): exposure unit, 50 (Y, M, C, K): development unit, 51Y: development roller, 51a: first inclined groove, 51b: second inclined groove, 51c: convex portion , 51d: inclined side surface, 51f: unevenness, 52Y: supply roller, 53Y: regulating blade, 54Y: toner stirring and conveying member, 55Y: toner receiving member, 56Y: sealing member, 57Y: developing chamber, 58Y: spacer, 70: intermediate Transfer belt, 80: secondary transfer unit, 90: fixing unit, 100: control unit, 200, 200 ′: rolling device, 201, 201 ′: first die, 201a, 201a ′: first inclined blade, 202, 202 ': 2 die, 202a, 202a ': second inclined blades, 203, 203': Guide block

Claims (8)

A developing device comprising: a developing roller having a spiral groove portion inclined at a predetermined angle with respect to an axial direction and a circumferential direction formed on a surface thereof, and an unevenness carrying an external additive formed in the groove portion. The developing device according to claim 1, wherein the external additive is a free external additive. The external additive is a free external additive, and the free external additive is insulative and has a normal charging polarity opposite to a normal charging polarity of a toner. Development device. The developing device according to claim 1, wherein a surface roughness of the unevenness is larger than an average particle diameter of the external additive. 5. The developing device according to claim 1, wherein the unevenness of the groove is formed by a die whose surface is blasted. 6. 5. The development according to claim 1, wherein the unevenness of the groove is formed by rolling a surface with a blasted die after a rolling process with a smooth surface die. apparatus. 5. The developing device according to claim 1, wherein the unevenness of the groove is formed by blasting after plating the surface. 6. A latent image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image with toner and developing the toner image on the latent image carrier;
A transfer device for transferring the toner image on the latent image carrier to a transfer medium;
With
The image forming apparatus according to claim 1, wherein the developing device is the developing device according to claim 1.

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