CN100517111C - Toner particle carrying roller, developing device, and image forming device - Google Patents

Abstract

A developing device includes a toner particle-bearing roller that bears toner particles on its surface and develops a latent image borne by an image-bearing member with those toner particles, the toner particle-bearing roller has a projection portion disposed on its surface, the projection portion having a top surface having a flat portion, and a width of the top surface being equal to or more than a volume average particle diameter of the toner particles.

Description

Toner particle carrying roller, developing device, and image forming device

technical field

The present invention relates to a toner particle carrying roller, a developing device, and an image forming device.

Background technique

Image forming apparatuses such as laser beam printers are already known. This image forming apparatus includes, for example, an image carrier for carrying a latent image, and a developing device for developing the latent image carried on the image carrier with toner particles. In the image forming apparatus, when an image signal or the like is sent from an external device such as a host computer, the developing device is positioned at a developing position opposite to the image carrier, and the toner particles in the developing device are carried on the image carrier by pairs of toner particles. The latent image is developed to form a toner image, and then the toner image is transferred to a medium to finally form an image on the medium.

In order to realize the said function of developing the latent image carried on the image carrier, the above-mentioned developing device has a toner particle carrying roller which carries toner particles on its surface, by which Toner particles are used to develop the latent image carried on the image carrier.

In addition, in the developing device, protrusions are formed on the surface of the toner particle carrying roller which should carry the toner particles appropriately. However, when a convex portion is formed on the surface of the toner particle carrying roller, a force may locally act on the toner particles from the convex portion due to the shape of the convex portion. For example, when the convex portion is relatively sharp, when the convex portion comes into contact with a toner particle, a force from the convex portion acts concentratedly on a part of the toner particle. In this way, when a force is concentrated locally on the toner particles from the convex portion, the toner may be deformed or the toner particles may be broken due to the force.

In addition, in order to properly support toner particles, a concave portion having a flat bottom surface and a side surface adjacent to the bottom surface may be provided on the surface of the toner particle carrying roller. Then, in some cases, toner particles, particularly fine powdery toner particles, may remain at the boundary portion between the bottom surface and the side surface.

In addition, some toner particle carrying rollers have regularly arranged concave portions and convex portions on the surface of the roller. The development of the latent image carried on the image carrier by the toner particles carried on the surface of the toner particle carrying roller is performed in a state where the toner particle carrying roller faces the image carrier However, it sometimes happens that the distance between the toner particles carried in the recesses of the toner particle carrying roller and the latent image carried on the image carrier is greater than the distance between the latent image carried in the toner particle carrying roller. The distance between the toner particles on the convex portion and the latent image is large. Then, in the relevant situation, the density of the toner image formed on the image bearing body by the toner particles carried in the recesses is higher than the density of the image formed by the toner particles carried in the convex portions. The density of the toner image on the carrier is light, and uneven shading may occur in the toner image.

Japanese Patent Application Laid-Open No. 2003-263018, Japanese Patent Laid-Open No. 1-102486, and Japanese Patent Laid-Open No. 5-142950 are examples of related art.

Contents of the invention

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to realize a developing device capable of suppressing deformation and the like of toner particles.

The main aspect of the present invention is the developing device described below.

A developing device having a toner particle carrying roller that carries toner particles on its surface and develops a latent image carried on an image carrier by the toner particles, Wherein, the toner particle carrying roller has a convex portion provided on the surface, the convex portion has a top surface having a flat portion, and the width of the top surface is equal to the volume average particle diameter of the toner particles. above.

In addition, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to realize a toner particle carrying roller capable of appropriately suppressing the stagnation of toner particles.

The main part of the present invention is the toner particle carrying roller described below.

A toner particle carrying roller having a concave portion provided on the surface, the concave portion having a flat bottom surface and a side surface adjacent to the bottom surface, a rounded corner is provided at the boundary between the bottom surface and the side surface, and the curvature of the rounded corner is The radius is at least half of the volume average particle diameter of the toner particles.

In addition, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to suppress occurrence of density unevenness in a toner image.

The main part of the present invention is the toner particle carrying roller described below.

A toner particle carrying roller having recesses and protrusions arranged regularly on a surface, wherein the maximum value of the ten-point average roughness of the recesses is greater than that of the ten-point average roughness of the protrusions The maximum value is small.

Other characteristics of the present invention will be clarified by the drawings and the following description.

For a more complete understanding of the invention and its advantages, reference is made to the following description and accompanying drawings.

Description of drawings

FIG. 1 is a schematic diagram of main components constituting a printer 10;

FIG. 2 is a block diagram illustrating a control unit of the printer 10 of FIG. 1;

3 is a conceptual diagram of a developing device;

4 is a cross-sectional view showing the main constituent parts of the developing device;

5 is a schematic perspective view of the developing roller 510, which shows the helical first groove portion 518a and the second groove portion 518b with different winding directions;

FIG. 6 is a schematic front view of the developing roller 510;

FIG. 7 is a schematic view showing the surface of the developing roller 510, which enlarges part A shown in FIG. 6;

FIG. 8 is a schematic diagram showing the cross-sectional shapes of the convex portion 519 and the concave portion 518;

FIG. 9 is a flowchart showing a manufacturing method of the developing roller 510;

10A to 10E are schematic diagrams of the transition of the developing roller 510 in the manufacturing process of the developing roller 510;

FIG. 11 is an explanatory view for explaining the roll forming process of the developing roller 510;

FIG. 12 is a diagram for explaining pitches in screens and latent images;

FIG. 13 is a diagram showing a modified example of the developing roller 510, and is a schematic diagram showing the cross-sectional shape of the convex portion 519;

FIG. 14 is a schematic diagram showing the cross-sectional shapes of the convex portion 1519 and the concave portion 1518 of the second embodiment;

FIG. 15 is a schematic perspective view of a developing roller 510 according to a third embodiment;

16 is a schematic front view of a developing roller 510 according to a third embodiment;

FIG. 17 is a schematic view showing a cross-sectional shape of a concave portion 2516 provided on the surface of the developing roller 510 of the third embodiment;

FIG. 18 is an explanatory view for explaining problems occurring in the recessed portion 2516 of the conventional example of the developing roller 510;

FIG. 19 is an explanatory view for explaining the effectiveness of the concave portion 2516 included in the developing roller 510 of the third embodiment;

20 is a schematic front view of a developing roller 510 according to a modified example of the third embodiment;

FIG. 21 is a schematic diagram showing a cross-sectional shape of a concave portion 2580 according to a modified example of the third embodiment;

FIG. 22 is a schematic perspective view of a developing roller 510 according to a fourth embodiment;

23 is a schematic front view of a developing roller 510 of a fourth embodiment;

FIG. 24 is an enlarged view of the central portion 510a of the developing roller 510 of the fourth embodiment;

FIG. 25 is a schematic diagram showing the shapes of a convex portion 3512, a concave portion 3515, and the like of the fourth embodiment;

Fig. 26 is a schematic view (Part 1) for explaining the effectiveness of the developing device of the fifth embodiment;

Fig. 27 is a schematic diagram (Part 2) for explaining the effectiveness of the developing device of the fifth embodiment;

28 is a schematic diagram (Part 3) for explaining the effectiveness of the developing device of the fifth embodiment;

FIG. 29 is an explanatory diagram showing the appearance configuration of the image forming system;

FIG. 30 is a block diagram showing the configuration of the image forming system shown in FIG. 29 .

Detailed ways

At least the following matters will be clarified from the description of this specification and the drawings.

The present invention provides a developing device having a toner particle carrying roller which carries toner particles on its surface and which is carried on an image bearing body by the toner particle pairs wherein the toner particle carrying roller has a convex portion provided on the surface, the convex portion has a top surface having a flat portion, and the top surface has a width equal to that of the toner The volume average particle size of the particles is above.

According to this developing device, when the top surface having the flat portion whose width is equal to or larger than the volume average particle diameter of the toner particle contacts the toner particle, force is dispersed from the convex portion (top surface) to act on the toner particle. on the toner particles. Therefore, according to the above-described developing device, it is possible to suppress the concentrated action of force from the convex portion on the local toner particle, and it is possible to suppress deformation of the toner particle or the like caused by the force.

In addition, there is a layer thickness restricting member which is in contact with the toner particle carrying roller from one axial end to the other end of the toner particle carrying roller, and is used to restrict the toner particle carrying roller The layer thickness of the toner particles on the toner particle carrying roller, and the layer thickness restricting member may also restrict the layer thickness by contacting the plane of the layer thickness restricting member with the toner particle carrying roller. thick.

When the layer thickness is restricted by the flat surface of the layer thickness restricting member in contact with the toner particle carrying roller, since the layer thickness restricting member presses the toner particles to the convex portion (top surface), it is easy to dislodge from the convex portion (top surface). Force is applied to the toner particles. Therefore, in the above case, the effect of providing the convex portion having the top surface on the surface of the toner particle carrying roller, that is, the effect of suppressing deformation of the toner particles can be effectively exerted.

In addition, the convex portion may have a side surface connected to the top surface, and a rounded corner may be formed at a connection portion between the top surface and the provided side surface.

When the connection portion between the top surface and the side surface is rounded, since no edge is formed at the connection portion, the force acting on the toner particles from the connection portion can be reduced. Thus in the above case, deformation of the toner particles can be suppressed.

In addition, the radius of curvature of the rounded corners may be half or more of the volume average particle diameter of the toner particles.

In the case where the radius of curvature of the rounded corners is smaller than half of the volume average particle diameter of the toner particles (ie, the average radius of the toner particles), when the toner particles contact the rounded corners, due to the intrusion of the rounded corners into the toner The local concentrated force from the rounded corner to the toner particle in the toner particle. On the other hand, when the radius of curvature of the rounded corners is at least half of the volume average particle diameter of the toner particles, since the rounded corners do not intrude into the toner particles, force is dispersed from the rounded corners to the toner particles. Thus in the above case, deformation of the toner particles and the like can be suppressed.

In addition, spiral groove portions are provided on the surface, the groove portions are inclined with respect to the axial direction and the circumferential direction of the toner particle carrying roller, and are equally spaced in the axial direction. Two types of grooves are formed by making the inclination angles of the grooves different, the convex portion is surrounded by the two types of grooves, and the depth of the grooves may be the toner The volume average particle diameter of the particles is less than twice.

In this case, since there are many toner particles located between the toner particle carrying roller and the layer thickness regulating member in the groove portion, at least some of the toner particle carrying roller and the layer thickness regulating member can be contacted. One, thus making the chargeability of the toner particles proper.

In addition, spiral groove portions are provided on the surface, the groove portions are inclined with respect to the axial direction and the circumferential direction of the toner particle carrying roller, and are equally spaced in the axial direction. Two types of grooves are formed by making the inclination angles of the grooves different, the convex portion is surrounded by the two types of grooves, and the latent image is formed in a region divided into a grid. In the axial direction, the grid can be formed by various types of intervals, and the axial interval of the groove portion can be longer than the longest interval among the various types of intervals in the grid. Small.

On the surface of the toner particle carrying roller, the amount of toner particles carried in the grooves is larger than that in places other than the grooves. Therefore, when the latent image is developed, only the portion opposite to the groove portion may be increased in density. In the case where the axial interval of the groove portion is larger than the longest interval among the plurality of types of intervals in the lattice, when developing a dot-like latent image formed in an area divided into a lattice shape, a A dot formed at a portion including the groove portion of the toner particle carrying roller and a dot formed at a portion not including the groove portion. In this case, periodic density unevenness occurs in the toner image on which the latent image has been developed. According to the developing device described above, the dots for developing the respective dot-like latent images are formed in the portion including the groove portion of the toner particle carrying roller. Therefore, it is possible to suppress density unevenness due to the groove portion in the developed toner image.

The present invention provides an image forming apparatus having a developing device including: an image carrier for carrying a latent image; and a toner particle carrying roller on which the toner particle carrying roller carrying toner particles on the surface, and developing the latent image carried on the image carrier by the toner particles; wherein the toner particle carrying roller has a convex portion provided on the surface , the convex portion has a top surface having a flat portion, and the width of the top surface is equal to or greater than the volume average particle diameter of the toner particles.

According to such an image forming apparatus, when the top surface having a flat portion and having a width larger than the volume average particle diameter of the toner particle contacts the toner particle, the toner particle is dispersed from the convex portion (top surface) to the toner particle. force. Therefore, according to the image forming apparatus described above, since the locally concentrated force acting from the convex portion on the toner particle can be suppressed, deformation of the toner particle or the like caused by the force can be suppressed.

The present invention also provides a developing device that has a toner particle carrying roller that carries the toner particles on its surface and is carried by the toner particle pair on a The latent image on the image carrier is developed, the toner particle carrying roller has a convex portion provided on the surface, at least the top end of the convex portion is provided with a rounded corner, and the radius of curvature of the rounded corner is the specified half or more of the volume average particle diameter of the above toner particles.

According to this developing device, when the rounded corner contacts the toner particle, force is dispersed from the convex portion (rounded corner) to the toner particle. Therefore, in the case of the above-mentioned developing device, since the force locally concentrated on the toner particles from the convex portion can be suppressed, deformation of the toner particles or the like caused by the force can be suppressed.

The toner particle carrying roller of the present invention has a concave portion provided on the surface, the concave portion has a flat bottom surface and a side surface adjacent to the bottom surface, a rounded corner is provided at the boundary between the bottom surface and the side surface, and the curvature of the rounded corner is The radius is half or more of the volume average particle diameter of the toner particles.

In this case, it is possible to realize a toner particle carrying roller that appropriately suppresses stagnation of toner particles.

In addition, it has the bottom surface and a non-recessed portion adjacent to the side surface on the opposite side, and a rounded corner is provided at the boundary between the non-recessed portion and the side surface, and the radius of curvature of the rounded corner is the volume average of the toner particles. more than half of the particle size.

In this case, in the boundary portion between the side surface adjacent to the flat bottom surface and the non-recessed portion, deformation of the toner particles can be suppressed by dispersing force to the toner particles.

The present invention also provides a developing device having a toner particle carrying roller having a concave portion provided on a surface, the concave portion having a flat bottom surface and a side surface adjacent to the bottom surface, A rounded corner is provided at the boundary between the bottom surface and the side surface, and the radius of curvature of the rounded corner is not less than half of the volume average particle diameter of the toner particles.

In this case, it is possible to realize a developing device in which retention of toner particles is appropriately suppressed.

The present invention provides a toner particle carrying roller having a concave portion provided on a surface, the concave portion having a first side surface and a second side surface, the first side surface and the second side surface having portions inclined into a planar shape and Opposite to each other, the first side and the second side are adjoined by the lower part of the recess, the boundary between the first side and the second side on the lower part is provided with rounded corners, and the radius of curvature of the rounded corners is It is half or more of the volume average particle diameter of the toner particles.

In this case, it is possible to realize a toner particle carrying roller that appropriately suppresses stagnation of toner particles.

In addition, the first side surface of the concave portion and the third side surface of another concave portion next to the concave portion are adjacent to the upper portion of the concave portion and the other concave portion, and the first side surface and the third side surface of the concave portion are adjacent to each other. The side boundary portion is provided with rounded corners having a radius of curvature equal to or greater than half the volume average particle diameter of the toner particles.

In this case, in the boundary portion of the first side surface and the third side surface, deformation of the toner particles can be suppressed by dispersing force to the toner particles.

The present invention provides a developing device having a toner particle carrying roller having a concave portion provided on a surface, the concave portion having a first side and a second side, the first side and the The second side has a portion inclined into a planar shape and is opposed to each other, the first side and the second side are adjoined by the lower portion of the recess, and the boundary portion of the first side and the second side on the lower portion Rounded corners are provided, and the radius of curvature of the rounded corners is not less than half of the volume average particle diameter of the toner particles.

In this case, it is possible to realize a developing device in which retention of toner particles is appropriately suppressed.

The present invention provides a toner particle carrying roller which has regularly arranged concave portions and convex portions provided on the surface, wherein the maximum value of the ten-point average roughness of the concave portions is greater than that of the convex portions. The maximum value of the ten-point average roughness is small.

According to the toner particle carrying roller described above, it is possible to suppress occurrence of density unevenness in a toner image.

In addition, the ten-point average roughness of the convex portion is maximized when the direction of the average line of the roughness curve when the ten-point average roughness is obtained is defined as the direction along the axial direction of the toner particle carrying roller.

In addition, the ten-point average roughness of the convex portion is minimum when the direction of the average line of the roughness curve when calculating the ten-point average roughness is set to be along the circumferential direction of the toner particle carrying roller.

In this case, the rotatability of toner particles can be improved.

In addition, the maximum value of the ten-point average roughness of the convex portion is not more than the volume average particle diameter of the toner particles.

In this case, the rotatability of the toner particles can be further improved.

The present invention provides a developing device having a toner particle carrying roller having recesses and protrusions arranged regularly on the surface, where the ten-point average of the recesses is The maximum value of the roughness is smaller than the maximum value of the ten-point average roughness of the convex portion.

In this case, it is possible to suppress occurrence of shading unevenness in the toner image.

The present invention provides a developing device having a toner particle carrying roller having a plurality of protrusions on a surface for carrying toner for developing a latent image particles, the toner particles are supplied to the toner particle carrying roller through a porous foam material, and the average distance between the openings of the holes in the axial direction of the toner particle carrying roller is larger than that of the convex portion The axial maximum width of the top surface is small.

According to the developing device, it is possible to prevent occurrence of a chip or a relatively low-density portion in a developed toner image.

(Example of Overall Configuration of Image Forming Apparatus)

A general configuration of a laser beam printer (hereinafter referred to as a printer) 10 as an example of an image forming apparatus will be described below using FIG. 1 . FIG. 1 is a schematic diagram of main components constituting a printer 10 . In FIG. 1 , the vertical direction is indicated by arrows. For example, the paper feed tray 92 is arranged at the lower part of the printer 10 , and the fixing unit 90 is arranged at the upper part of the printer 10 .

(Example of structure of printer 10)

The printer 10 of this embodiment, as shown in FIG. , the intermediate transfer body 70, the cleaning unit 75, and also has: a secondary transfer unit 80, a fixing unit 90, a display unit 95 formed of a liquid crystal panel as a notification means for notifying the user, and controlling these units etc. to servo print Operation of the control unit 100.

The photoreceptor 20 has a cylindrical conductive substrate and a photosensitive layer formed on its outer peripheral surface, and is rotatable around a central axis, and in this embodiment, rotates clockwise as indicated by an arrow in FIG. 1 .

The charging unit 30 is a device for charging the photoreceptor 20 , and the exposure device 40 is a device for forming a latent image on the photoreceptor 20 charged by irradiating laser light. The exposure device 40 includes: a semiconductor laser for emitting a laser beam as light; a polygon mirror unit for rotating a polygon mirror; and various types of lenses such as f-θ lenses. The exposure device 40 irradiates the charged photoreceptor 20 with a modulated laser beam based on an image signal input from an unillustrated host computer such as a personal computer or a word processor. At this time, the laser beam emitted from the semiconductor laser is irradiated on the polygon mirror. The laser beam irradiated on the polygon mirror changes the reflection angle by the rotation of the polygon mirror, and scans on the photoreceptor 20 through the lens. The laser beam is turned on/off (off) at a predetermined timing, thereby forming a dot-like latent image on a grid-divided area on the photoreceptor 20 rotating at a predetermined speed. These point-like latent images constitute a latent image. Here, since a latent image is formed, it cannot be seen with the naked eye.

The YMCK developing unit 50 uses toner particles (hereinafter simply referred to as toner T) accommodated in the developing device, that is, black (K) toner accommodated in the black developing device 51 , black (K) toner accommodated in the magenta developing device 52 , Magenta (M) toner, cyan (C) toner accommodated in cyan developing device 53 , and yellow (Y) toner accommodated in yellow developing device 54 are formed on photoreceptor 20 The latent image is developed.

The YMCK developing unit 50 can change the positions of the four developing devices 51 , 52 , 53 , and 54 by being rotated while the four developing devices 51 , 52 , 53 , and 54 are attached. Right now. The YMCK developing unit 50 supports the four developing devices 51, 52, 53, 54 through four supporting parts 55a, 55b, 55c, 55d, and the four developing devices 51, 52, 53, 54 can be 50a as the center and rotate while maintaining its relative position. After the image formation of one page is completed, the latent images formed on the photoreceptor 20 are sequentially processed using the toner T contained in the respective developing devices 51 , 52 , 53 , and 54 selectively facing the photoreceptor 20 . development. In addition, each of the four developing devices 51 , 52 , 53 , 54 can be freely attached to and detached from the supporting portion of the YMCK developing unit 50 . In addition, each developing device will be described in detail later.

The primary transfer unit 60 is used to transfer the single-color toner image formed on the photoreceptor 20 to the intermediate transfer body 70. A full-color toner image is formed on the transfer body 70 .

The intermediate transfer body 70 is provided with a tin vapor-deposited layer on the surface of the PET film, and a laminated endless belt of semiconductive paint is formed on the surface layer. Peripheral speed is driven by rotation.

The secondary transfer unit 80 is used to transfer the single-color toner image or the full-color toner image formed on the intermediate transfer body 70 to a medium such as paper, film, or cloth.

The fixing unit 90 is used to thermally bond the single-color toner image or the full-color toner image transferred onto the medium to form a permanent image.

The cleaning unit 75 is provided between the primary transfer unit 60 and the charging unit 30 , and has a cleaning blade 76 made of rubber that is in contact with the surface of the photoreceptor 20 . After the toner image is transferred, the toner T remaining on the photoreceptor 20 is swept off and removed by the cleaning blade 76 .

As shown in FIG. 2, the control unit 100 is composed of a main controller 101 and a unit controller 102. An image signal and a control signal are input to the main controller 101. According to an instruction based on the image signal and the control signal, the unit controller 102 controls all units. The above-mentioned respective units and the like are used to form an image.

(Example of operation of printer 10)

Next, the operation of the printer 10 configured as described above will be described.

First, when an image signal and a control signal from a host computer not shown in the figure are input into the main controller 101 of the printer 10 via the interface (I/F) 112, the unit is controlled based on an instruction from the main controller 101. Under the control of the device 102, the photoreceptor 20 and the intermediate transfer body 70 rotate. The photoreceptor 20 is sequentially charged by the charging unit 30 at the charging position while rotating.

The charged area of the photoreceptor 20 reaches the exposure position as the photoreceptor 20 rotates, and a latent image corresponding to the image information of the first color, for example, yellow Y is formed in this area by the exposure unit 40 . In addition, the YMCK developing unit 50 places a yellow developing device 54 containing yellow (Y) toner at a developing position opposite to the photoreceptor 20 .

The latent image formed on the photoreceptor 20 reaches a developing position as the photoreceptor 20 rotates, and is developed with a yellow developer by the yellow developing device 54 . Thus, a yellow toner image is formed on the photoreceptor 20 .

The yellow toner image formed on the photoreceptor 20 reaches the primary transfer position as the photoreceptor 20 rotates, and is transferred onto the intermediate transfer body 70 by the primary transfer unit 60 . At this time, a primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the primary transfer unit 60 . And during this period, the photoreceptor 20 is in contact with the intermediate transfer body 70 , and the secondary transfer unit 80 is separated from the intermediate transfer body 70 .

For the second color, the third color, and the fourth color, each developing device sequentially executes the above processing, whereby the four-color toner images corresponding to the respective image signals are superimposedly transferred onto the intermediate transfer body 70 . Thereby, a full-color toner image is formed on the intermediate transfer body 70 .

The full-color toner image formed on the intermediate transfer body 70 reaches the secondary transfer position as the intermediate transfer body 70 rotates, and is transferred onto a medium by the secondary transfer unit 80 . The medium is conveyed from a paper feed tray 92 to a secondary transfer unit 80 via a paper feed roller 94 and a register roller 96 . In addition, when the transfer operation is performed, the secondary transfer unit 80 is pressed against the intermediate transfer body 70 and a secondary transfer voltage is applied thereto.

The full-color toner image transferred to the medium is thermally bonded to the medium by heat and pressure from the fixing unit 90 .

On the other hand, after the photoreceptor 20 passes through the primary transfer position, the toner T adhering to its surface is swept off by the cleaning blade 76 supported on the cleaning unit 75, and is ready for forming the next latent image. charging. The swept-off toner T is recovered in a remaining toner recovery section included in the cleaning unit 75 .

(Outline of the control unit)

Next, the configuration of the control unit 100 will be described with reference to FIG. 2 . The main controller 101 of the control unit 100 is electrically connected to a host computer via an interface 112 and includes an image memory 113 for storing image signals input from the host computer. The unit controller 102 is electrically connected to each unit of the device body (charging unit 30, exposure unit 40, YMCK developing unit 50, primary transfer unit 60, cleaning unit 75, secondary transfer unit 80, fixing unit 90, display unit 95). The connection detects the state of each unit by receiving signals from sensors included in these units, and controls each unit based on a signal input from the main controller 101 .

(Outline of developing device)

Next, a configuration example and an operation example of the developing device will be described with reference to FIGS. 3 and 4 . FIG. 3 is a conceptual diagram of a developing device. FIG. 4 is a cross-sectional view showing the main constituent parts of the developing device. The cross-sectional view shown in FIG. 4 shows a cross-section of the developing device taken along a plane perpendicular to the longitudinal direction shown in FIG. 3 . In addition, in FIG. 4 , as in FIG. 1 , the vertical direction is indicated by arrows. For example, the central axis of the developing roller 510 is below the central axis of the photoreceptor 20 . In addition, a state where the yellow developing device 54 is located at a developing position opposite to the photoreceptor 20 is shown in FIG. 4 .

While the YMCK developing unit 50 is provided with a black developing device 51 containing black (K) toner, a magenta developing device 52 containing magenta (M) toner, and a cyan developing device 52 containing cyan (C) toner, The yellow developing device 53 and the yellow developing device 54 containing yellow (Y) toner, but since the structures of the developing devices are the same, the yellow developing device 54 will be described below.

(Structure Example of Developing Device)

The yellow developing device 54 has a developing roller 510 as an example of a toner particle carrying roller, an upper seal 520, a toner container 530, a casing 540, a toner supply roller 550, and one layer thickness regulating member. Exemplary limiting scraper 560 and the like.

Toner particles (toner T) are carried on the surface of the developing roller 510 , and the latent image carried on the photoreceptor 20 is developed by the developing roller 510 through the toner particles. The developing roller 510 is a member made of aluminum alloy, iron alloy, or the like. The surface of the developing roller 510 is provided with recesses 518 and protrusions 519 (see FIG. 6 ), which are examples of grooves. The surface shape of the developing roller 510 will be described in detail later.

Also, as shown in FIG. 3 , the developing roller 510 is supported on both end portions in the longitudinal direction of the developing device (the axial direction of the developing roller 510 ), and is rotatable around a central axis. As shown in FIG. 4 , the developing roller 510 rotates in a direction (counterclockwise in FIG. 4 ) opposite to the rotation direction of the photoreceptor 20 (clockwise in FIG. 4 ). The central axis thereof is located below the central axis of the photoreceptor 20 .

In addition, in a state where the yellow developing device 54 is opposed to the photoreceptor 20 , there is a gap between the developing roller 510 and the photoreceptor 20 . That is, the yellow developing device 54 develops the latent image formed on the photoreceptor 20 in a non-contact state. In addition, when developing the latent image formed on the photoreceptor 20 , an alternating electric field is formed between the developing roller 510 and the photoreceptor 20 .

A case 540 is manufactured by welding a plurality of integrally formed resin case parts, that is, an upper case part 542 and a lower case part 544 . The toner containing body 530. The toner accommodating body 530 is divided into two toner accommodating portions, ie, a first toner accommodating portion 530a, by a partition wall 545 protruding inwardly from the inner wall (up-and-down direction in FIG. 4 ) for isolating the toner T. and the second toner containing portion 530b.

The upper parts of the first toner storage portion 530a and the second toner storage portion 530b communicate with each other, and the movement of the toner T is restricted by the partition wall 545 in the state shown in FIG. 4 . However, when the YMCK developing unit 50 rotates, once the toner contained in the first toner accommodating portion 530a and the second toner accommodating portion 530b is concentrated on the side of the communication portion on the upper side of the developing position, it returns In the state shown in FIG. 4 , these toners are mixed and returned to the first toner accommodating portion 530 a and the second toner accommodating portion 530 b. That is, the toner T in the developing device can be properly stirred by the rotation of the YMCK developing unit 50 .

Therefore, in the present embodiment, although a stirring member is not provided in the toner container 530 , a stirring member for stirring the toner T contained in the toner container 530 may be provided. Also, as shown in FIG. 4 , the casing 540 (ie, the first toner accommodating portion 530 a ) has an opening 572 at a lower portion, and the developing roller 510 is disposed opposite to the opening 572 .

The toner supply roller 550 is constituted by a roller portion formed of an elastic porous foam material such as urethane foam, and a shaft as a rotation center of the roller portion. Both ends of the shaft of the toner supply roller 550 are supported by the casing 540 so as to be freely rotatable around the shaft. The roller portion is accommodated in the first toner accommodating portion 530a (inside the housing 540) of the housing 540, and accommodates the toner T accommodated in the first toner accommodating portion 530a into the hole. , the toner accommodated in the holes is mainly supplied to the developing roller 510 . The toner supply roller 550 is provided directly below the first toner accommodating portion 530a. The toner T accommodated in the first toner accommodating portion 530 a is supplied to the developing roller 510 via the toner supply roller 550 at the lower portion of the toner accommodating portion 530 a. In addition, the toner supply roller 550 peels off the excess toner T remaining on the developing roller 510 after development from the developing roller 510 . At this time, the wall area surrounded by the plurality of holes formed on the toner supply roller 550 comes into contact with the developing roller 510 , thereby peeling off the toner remaining on the developing roller 510 . That is, the toner remaining on the developing roller 510 is peeled off mainly through the wall region of the toner supply roller 550 .

The toner supply roller 550 and the developing roller 510 are assembled to the housing 540 in a state of being pressed against each other. Therefore, the roller portion of the toner supply roller 550 is in contact with the developing roller 510 in an elastically deformed state. In addition, the shaft body is located below the central axis of rotation of the developing roller 510 . The toner supply roller 550 rotates in a direction (clockwise in FIG. 4 ) opposite to that of the developing roller 510 (counterclockwise in FIG. 4 ). In this embodiment, a peripheral speed difference is provided between the toner supply roller 550 and the developing roller 510, and the surface moving speed of the toner supply roller 550 when the toner supply roller 550 rotates is approximately 1.5 times the surface moving speed of the developing roller 510 at that time.

The upper seal 520 is in contact with the developing roller 510 along the axial direction of the developing roller 510, allowing the toner T remaining on the developing roller 510 to move into the housing 540 after passing through the developing position, and restricting the toner T in the housing 540 Move out of the housing 540. The upper seal 520 is a film made of polyethylene film or the like. The upper seal 520 is supported by an upper seal support portion 526 a of a holder, and its longitudinal direction is arranged along the axial direction of the developing roller 510 . The contact position where the upper seal 520 is in contact with the developing roller 510 is located above the central axis of the developing roller 510 .

In addition, between the surface of the upper seal 520 opposite to the contact surface 520b with the developing roller 510 (this surface is referred to as the opposite surface 520c) and the upper seal support portion 526a, there is a foam rubber seal in a compressed state. (Moltopren) and other elastic bodies constitute the upper sealing elastic member 524. The upper seal urging member 524 urges the upper seal 520 toward the developing roller 510 under the action of its urging force, thereby pressing the upper seal 520 toward the developing roller 510 .

The regulating blade 560 is in contact with the developing roller 510 over the entire area from one axial end to the other end of the developing roller 510 through the contact portion 562a, and regulates the layer thickness of the toner T carried on the developing roller 510, And charge is applied to the toner T carried on the developing roller 510 . As shown in FIG. 4 , this regulating scraper 560 has a rubber portion 562 and a rubber support portion 564 .

The rubber portion 562 is made of silicone rubber, urethane rubber, or the like, and is in contact with the developing roller 510 .

The rubber support portion 564 is composed of a thin plate 564a and a thin plate support portion 564b, and supports the rubber portion 562 at one end portion 564d in the lateral direction (that is, the end portion on the thin plate 564a side). The thin plate 564a is made of phosphor bronze, stainless steel, or the like, and has elasticity. The thin plate 564a supports the rubber portion 562 and presses the rubber portion 562 against the developing roller 510 by its elastic force. The thin plate support portion 564b is a metal plate disposed at the other end 564e in the lateral direction of the rubber support portion 564 . One side of the thin plate 564a supports the rubber portion 562, and the opposite end thereof is supported by the thin plate supporting portion 564b, so that the thin plate supporting portion 564b is attached to the thin plate 564a in this state.

The front end 560a of the scraper 560, which is the end opposite to the sheet supporting portion 564b, does not come into contact with the developing roller 510, and the portion (ie, the contact portion 562a) separated from the front end 560a by a predetermined distance contacts the developing roller with a constant contact width. 510 contact. That is, the restricting blade 560 is in contact with the developing roller 510 not at the edge but near its abdomen, and the layer is restricted by contacting the developing roller 510 with a flat surface (specifically, a flat surface of the rubber portion 562 ) of the restricting blade 560 . thick. In addition, the regulation blade 560 is arranged so that the front end 560 a thereof faces the upstream side in the rotation direction of the developing roller 510 , that is, so-called reverse contact. The contact position where the regulation blade 560 contacts the developing roller 510 is below the central axis of the developing roller 510 and below the central axis of the toner supply roller 550 . In addition, the restriction blade 560 can also function to prevent the toner T from leaking from the toner container 530 by being in contact with the developing roller 510 in the axial direction.

(Operation example of developing device)

In the thus configured yellow developing device 54 , the toner supply roller 550 supplies the toner T contained in the toner container 530 to the developing roller 510 . The toner T supplied to the developing roller 510 reaches the contact position of the regulating blade 560 as the developing roller 510 rotates, and when passing through the contact position, the layer thickness is restricted and charges are applied at the same time. The toner T on the developing roller 510 whose layer thickness is limited and charged is applied reaches the developing position opposite to the photoreceptor 20 by the further rotation of the developing roller 510, and is used at the developing position under the action of an alternating electric field. The latent image formed on the photoreceptor 20 is developed under action. The toner T on the developing roller 510 passing the developing position as the developing roller 510 further rotates passes the upper seal 520 and is recovered into the developing device instead of being swept off by the upper seal 520 . In addition, the toner T remaining on the developing roller 510 is peeled off by the toner supply roller 550 .

(Surface shape of developing roller 510)

The surface shape of the developing roller 510 will be described below with reference to FIGS. 5 to 8 . FIG. 5 is a schematic perspective view of the developing roller 510 showing the recess 518 . FIG. 6 is a schematic front view of the developing roller 510 . FIG. 7 is a schematic view showing the surface of the developing roller 510 , which is an enlarged view of part A shown in FIG. 6 . FIG. 8 is a schematic view showing the cross-sectional shapes of the convex portion 519 and the concave portion 518 .

In FIGS. 5 to 7 , arrows indicate the axial direction of the developing roller 510 , and in FIG. 8 , arrows indicate the longitudinal direction of the first concave portion 518 a. In addition, in FIGS. 5 to 8 , in order to facilitate understanding of the drawings, the proportions of the convex portion 519 and the like are different from actual ones. In addition, in FIGS. 6 and 7 , the arrow direction indicated by symbol X indicates the longitudinal direction of the first concave portion 518a, and the arrow direction indicated by symbol Y indicates the longitudinal direction of the second concave portion 518b. FIG. 8 shows a section along the longitudinal direction of the first concave portion 518 a indicated by a symbol Y in FIG. 6 . In addition, when the cross section of the convex portion 519 and the concave portion 518 is taken along the longitudinal direction of the second concave portion 518b shown by the symbol X in FIG. It is the same as the cross-sectional shape of the concave portion 518 .

As shown in FIGS. 5 and 6 , the developing roller 510 has a cylindrical portion 510 a and a shaft portion 510 b. The cylindrical portion 510a carries toner particles on its surface. The cylindrical portion 510a is formed of a single material such as aluminum alloy, and has a concave-convex portion 512 and a non-corrugated portion 514 formed on the surface thereof. The shaft portions 510b are located at both ends in the axial direction of the developing roller 510, and are supported by the casing 540 via bearings not shown in the figure.

The concave-convex processed portion 512 is a portion located at the center in the axial direction of the developing roller 510, and its surface is concave-convex processed to properly support the toner T (both the convex portions 519 and the concave portions 518 of the concave-convex processed portion 512 function as Function of a toner carrying portion carrying toner particles (toner T)). In the present embodiment, so-called roll forming is used as the concave-convex processing (the roll forming process will be described in detail in the section of the manufacturing method of the developing roller 510 described later). On the other hand, a concave portion 518 and a convex portion 519 are formed on the surface of the concave-convex processed portion 512 . More specifically, grooves are formed on the surface of the unevenly processed portion 512 by roll forming, whereby the unevenly processed portion 512 has concave portions 518 and convex portions 519 .

As shown in FIG. 5 , the recesses 518 are spiral grooves inclined with respect to the axial direction and the circumferential direction of the developing roller 510 and formed at equal intervals in the axial direction. The concave portion 518 is formed into two types (first concave portion 518 a and second concave portion 518 b ) by making different angles of inclination with respect to the axial direction and the circumferential direction of the developing roller 510 .

That is, the first concave portion 518 a is formed in a spiral shape at 45 degrees in the counterclockwise direction from the axial direction of the developing roller 510 , and the second concave portion 518 b is formed in a spiral shape at 45 degrees in the clockwise direction from the axial direction of the developing roller 510 . The way is formed as a spiral. Therefore, the intersection angle of the first concave portion 518a and the second concave portion 518b is 90 degrees. In addition, the pitch of the first concave portion 518 a and the second concave portion 518 b in the axial direction of the developing roller 510 is equal, and in this embodiment, it is about 112 μm as shown in FIG. 7 .

As shown in FIG. 6 , the convex portion 519 is surrounded by the two types of concave portions, namely, the first concave portion 518a and the second concave portion 518b. The protrusion 519 has a top surface 519a and a side surface 519b connected to the top surface 519a.

As shown in FIG. 8, the top surface 519a has a flat portion. As shown in FIG. 7, the shape of the top surface 519a is substantially square. The top surface 519a is formed in such a manner that one of the two diagonals of the square of the top surface 519a is along the axial direction of the developing roller 510, and the other diagonal is along the circumferential direction of the developing roller 510. . In addition, the width H of the top surface 519 a is equal to or larger than the volume average particle diameter (7 μm) of the toner particles, and is about 30 μm in the present embodiment.

As shown in FIG. 8 , the side surface 519b is a slope that is continuous with the flat bottom surface 518c of the concave portion 518 and is inclined relative to the bottom surface 518c. Furthermore, the inclination angle of the side surface 519b with respect to the bottom surface 518c of the concave portion 518 (the angle indicated by the symbol β in FIG. 8 ) is 45 degrees or less, and in this embodiment, the inclination angle is 45 degrees.

In addition, as shown in FIG. 8, a rounded corner 519d is formed at a connecting portion 519c of the top surface 519a and the side surface 519b. The radius of curvature of the rounded corners 519d is at least half of the volume average particle diameter (7 μm) of the toner particles, and is 20 μm in this embodiment. In this embodiment, as shown in FIG. 8 , the cross-sectional shape of the fillet 519 d is an arc connecting the top surface 519 a and the side surface 519 b. In this case, the aforementioned radius of curvature has the same magnitude as the radius of the arc.

In addition, the height of the convex portion 519 (the depth of the concave portion 518 ), that is, the distance between the top surface 519 a of the convex portion 519 and the bottom surface 518 c of the concave portion 518 is not more than twice the volume average particle diameter (7 μm) of the toner particles. In this embodiment, since the depth of the concave portion 518 is about 7 μm, it is the same size as the volume average particle diameter of the toner particles. In addition, the width of the concave portion 518 is about 30 μm, and the groove angle (the angle indicated by the symbol α in FIG. 8 ) is about 90 degrees.

As shown in FIG. 6 , the non-concave-convex portion 514 is a portion not subjected to the above-described concavo-convex processing (roll forming process) on its surface. The non-corrugated part 514 is located between the corrugated part 512 and the shaft part 510b in the axial direction of the developing roller 510, and its surface is smooth (the ten-point average roughness Rz of the surface is 1 μm or less).

(Manufacturing method of developing roller 510)

Next, a method of manufacturing the developing roller 510 having the above-described surface shape (concavity 518 and convexity 519 ) will be described with reference to FIGS. 9 , 10A to 10E , and 11 . FIG. 9 is a flowchart illustrating a method of manufacturing the developing roller 510 . 10A to 10E are schematic diagrams showing transitions of the developing roller 510 in the manufacturing process of the developing roller 510 . FIG. 11 is an explanatory view for explaining the roll forming process of the developing roller 510 . 10A to 10C show the cross section of the pipe 600 , and FIGS. 10D and 10E show the periphery of the pipe 600 .

First, as shown in FIG. 10A , a pipe material 600 as a base material of the cylindrical portion 510 a of the developing roller 510 is prepared (step s102 ). The wall thickness of the pipe 600 is 0.5-3 mm.

Next, as shown in FIG. 10B , flange press-fitting portions 602 are formed at both end portions in the longitudinal direction of the pipe material 600 (step s104 ). The flange press fitting portion 602 is produced by cutting.

Next, as shown in FIG. 10C, the flange 604 constituting the shaft portion 510b of the developing roller 510 is press-fitted into the flange press-fitting portion 602 (step s106). In order to reliably fix the flange 604 on the pipe 600 , after the flange 604 is pressed in, the flange 604 may be glued or welded on the pipe 600 .

Next, as shown in FIG. 10D , centerless grinding is performed on the surface of the pipe material 600 into which the flange 604 is pressed (step s108 ). The centerless grinding is performed over the entire surface of the surface, and the ten-point average roughness Rz of the surface after the centerless grinding becomes 1.0 μm or less.

Next, as shown in FIG. 10E , recesses 518 and protrusions 519 are formed by roll forming on portions of the pipe material 600 into which the flange 604 has been press-fitted, which correspond to the recessed and projected portions 512 (step s110 ). In the present embodiment, so-called through flow forming (also referred to as step rolling) using two round dies 650 and 652 is carried out.

That is, as shown in FIG. 11, two round dies 650, 652 are arranged to clamp the pipe material 600 as a workpiece. In a state where the two round dies 650, 652 are pressed against the pipe material 600, the two round dies 650, 652 are rotated in the same direction (see FIG. 11). On the surface of the round dies 650 , 652 there are protrusions 650 a , 652 a for forming the recesses 518 , and the protrusions 650 a , 652 a deform the pipe 600 to form the recesses 518 and protrusions 519 on the pipe 600 . In addition, in the through-type roll forming process, by the rotation of the round dies 650, 652, the pipe material 600 is rotated in the direction opposite to the rotation direction of the round dies 650, 652 (see FIG. Move in the direction indicated by the mark H. Then, in the portion corresponding to the concave-convex processed portion 512, the first concave portion 518a in the concave portion 518 is formed by the protrusion 650a of the round die 650, and the first concave portion 518a in the concave portion 518 is formed by the protrusion 652a of the round die 652. Two recesses 518b. In addition, as described above, a rounded corner 519d (FIG. 8) is formed at the connection portion 519c of the convex portion 519 of the developing roller 510, and the protrusions 650a and 652a of the round die are shaped to form the rounded corner 519d.

In the above-mentioned manufacturing method of the developing roller 510, the convex portion 519 having the top surface 519a having a flat portion is formed on the surface of the developing roller 510 by roll forming (step s110), and the top surface The width of 519a is equal to or larger than the volume average particle diameter of the toner particles.

(Effectiveness of the developing device in this embodiment)

As described above, the toner particle carrying roller (developing roller 510 ) of the developing devices 51 , 52 , 53 , and 54 of the present embodiment has the convex portion 519 having a top portion having a flat portion as shown in FIG. 8 . The surface 519a and the width H of the top surface 519a are equal to or greater than the volume average particle diameter of the toner particles. Deformation of toner particles and the like can thereby be suppressed. Detailed description will be given below.

When protrusions are formed on the surface of the developing roller 510 , a force may locally act from the protrusions to the toner particles due to the shape of the protrusions. For example, when the convex portion is relatively sharp, when the convex portion contacts a toner particle, a force may be concentrated locally on the toner particle from the convex portion. In this way, when a force is concentrated locally on the toner particles from the convex portion, the toner may be deformed or the toner particles may be broken due to the force.

On the other hand, as in this embodiment, in the case of providing the convex portion 519 having the top surface 519a having a flat portion, and the width of the top surface 519a is equal to or greater than the volume average particle diameter of the toner particles, when the When the top surface 519a comes into contact with the toner particles, force is distributed to the toner particles from the convex portion 519 (top surface 519a). Therefore, according to the developing roller 510 of the present embodiment, it is possible to suppress the locally concentrated force from the convex portion 519 on the toner particles, and to suppress the deformation of the toner particles due to the force.

(Relationship between concave portion 518 and latent image)

As described above, the laser beam printer forms a latent image on the photoreceptor 20 using a laser beam, and visualizes the formed latent image as a toner image by the toner carried on the developing roller 510 . On the photoreceptor 20 at this time, a dot-shaped latent image is formed on an area divided into a lattice shape, that is, a so-called screen, by turning on/off the laser beam scanned in the main scanning direction. Then, a latent image is constructed from these point-like latent images.

Also, as in the present embodiment, for the developing roller 510 having clearly defined concave portions 518 and convex portions 519 , for example, there is a concern that more toner particles T enter the concave portions 518 than the convex portions 519 . In this case, there is a concern that the density of the portion developed by the concave portion 518 and the portion developed by the convex portion 519 may be different in the toner image. In particular, although the effect is relatively small on images that do not have a large area such as letters or lines, density unevenness tends to appear on images that have a large area such as photographs or illustrations. This phenomenon is particularly noticeable when the axial interval of the recesses 518 formed on the developing roller 510 is larger than the lattice interval in the main scanning direction (direction corresponding to the axial direction of the developing roller 510 ) of the screen. Even dots originally formed with the same density differ in density depending on whether the dots are developed by the concave portions 518 of the developing roller 510 or by the convex portions 519 .

Therefore, in the developing roller 510 of the present embodiment, the axial pitch of the recesses 518 is smaller than the longest pitch of the grid when forming an image with a large area such as a photograph or an illustration. Here, the grid pitch in the main scanning direction (direction corresponding to the axial direction of the developing roller 510) of the latent image when forming an image having an area such as a photograph or an illustration is not a dot pitch at which a laser beam printer can form an image with the highest resolution. (That is, the lattice can form various types of pitches in the main scanning direction (axial direction)). This is for the purpose of forming dots with a lower resolution than the highest resolution that the printer has when forming an image with a large area such as a photograph or an illustration by a laser beam printer, and by having gradation at each dot and improve the overall image quality.

FIG. 12 is a diagram for explaining pitches in screens and latent images. As shown in the figure, for example, in the case where the highest resolution of the printer is 600dpi (the pitch is 42.5μm), when the resolution of the latent image is set to 600dpi, the area where the dot-like latent image can be formed is divided into a pitch of 42.5 μm lattice shape. Therefore, in each divided area, the gradation can only be expressed by the presence or absence of the dotted latent image (upper row in FIG. 12 ).

Therefore, when forming an image with a large area, for example, three dot latent images with a resolution of 600dpi are taken as one dot latent image, and the semiconductor laser changes the laser emission within the time that can respond to the three dot latent images The time length of the beam, thus expressing the tone in the resolution of 600dpi (lower part of Figure 12). At this time, the resolution at the time of forming an image having a large area is 200 dpi, and the area where a dot-like latent image can be formed is divided into a grid with a pitch of 127.5 μm. Therefore, as shown in FIG. 8 , in the developing roller 510 of the present embodiment, by setting the pitch of the axial recesses 518 to about 112 μm, a region of 200 dpi, that is, a grid pattern with a pitch of 127.5 μm is formed. Each dot-shaped latent image of the latent image is developed at all the portions including the concave portion 518 and the convex portion 519 of the developing roller 510, so that density unevenness in the developed toner image can be suppressed.

In this embodiment, an example is given in which the maximum resolution of the laser beam printer is 600 dpi, and when forming images such as photographs, dot-like latent images can be formed, and the axial pitch of the grid-like regions is 127.5 μm. The axial pitch of the recesses 518 of the developing roller 510 was 112 μm. However, the present invention is not limited to this case, and the axial pitch of the concave portion 518 of the developing roller 510, and the axial pitch of the dot-shaped latent image formed by the latent image when forming an image such as a photograph and divided into grid-like regions may be smaller.

Other Embodiments (Second Embodiment to Fourth Embodiment, etc.)

The developing device of the present invention has been described above based on the above-mentioned embodiments, but the above-mentioned embodiments of the present invention are only for easy understanding of the embodiments of the present invention, and do not limit the present invention. The present invention can be changed and improved without departing from the gist of the present invention, and of course, the present invention also includes its equivalents.

In the above embodiments, an intermediate transfer type full-color laser beam printer has been described as an example of an image forming apparatus, but the present invention is also applicable to full-color laser beam printers other than the intermediate transfer type, black and white It is used in various image forming apparatuses such as printers, copiers, and facsimile machines.

In addition, the photoreceptor is not limited to a so-called photosensitive roller formed by providing a photosensitive layer on the outer peripheral surface of a cylindrical conductive substrate, and may be formed by providing a photosensitive layer on the surface of a belt-shaped conductive substrate. The so-called photosensitive zone.

In addition, in the above-mentioned embodiment, the volume average particle diameter of the toner particles is 7 μm as an example.

In addition, in the above-mentioned embodiment, as shown in FIG. 4 , the developing devices 51 , 52 , 53 , and 54 are in contact with the developing roller 510 from one end portion to the other end portion in the axial direction of the developing roller 510 . And a layer thickness regulating member (regulating blade 560 ) for regulating the layer thickness of toner particles carried on the developing roller 510 . The limiting blade 560 limits the layer thickness by contacting the developing roller 510 with a flat surface of the limiting blade 560 . But not limited to the above. For example, the limiting blade 560 may also limit the layer thickness by contacting the developing roller 510 at its edge.

When the regulating blade 560 restricts the layer thickness by contacting the developing roller 510 with its edge, the toner carried on the convex portion 519 is swept off by the regulating blade 560 . On the other hand, as shown in the above-mentioned embodiment, in the case where the layer thickness is restricted by the flat surface of the restricting blade 560 coming into contact with the developing roller 510 , since the restricting blade 560 presses the toner particles toward the convex portion 519 (top surface 519 a ), therefore, toner particles are hardly swept off by the regulating blade 560 . When the regulating blade 560 presses the toner particles, a force is easily applied from the convex portion 519 to the toner particles carried on the convex portion 519 . Therefore, in the above case, the effect of providing the convex portion 519 having the top surface 519 a on the surface of the developing roller 510 , that is, the effect of suppressing the deformation of the toner particles, is more effective. Therefore, the above-mentioned embodiment is more preferable.

Moreover, in the said embodiment, as shown in FIG. 8, the convex part 519 has the side surface 519b connected to the top surface 519a. A fillet 519d is formed at a connecting portion 519c of the top surface 519a and the side surface 519b. But not limited to the above. For example, as shown in FIG. 13 , the connection portion 519c may not be formed with a rounded corner 519d but may be formed with a corner.

In the case where the connecting portion 519c forms a corner, when the toner particle comes into contact with the corner, it is easy to locally concentrate force from the corner as an edge to the toner particle. On the contrary, when the rounded corner 519d is formed at the connecting portion 519c, since no edge is formed at the connecting portion 519c, the force acting on the toner particles from the connecting portion 519c can be reduced. Therefore, the above-described embodiment is more preferable from the viewpoint that deformation of toner particles can be suppressed, and the like.

Here, the surface structure of the developing roller 510 of the modified example shown in FIG. 13 will be described. FIG. 13 is a schematic view of a modified example of the developing roller 510 , and is a schematic view showing the cross-sectional shape of the convex portion 519 . The developing roller 510 shown in FIG. 13 has the same surface structure as the developing roller 510 shown in FIG. 8 (ie, has convex portions 519 and concave portions 518 ), except that the connecting portion 519c becomes an angle. Therefore, as shown in FIG. 13, the developing roller 510 of the modified example also has a flat surface 519a. The width H of the top surface 519a is equal to or larger than the volume average particle diameter of the toner particles (specifically, the width H is about 36 μm).

In addition, in the above-described embodiment, as shown in FIG. 8 , the radius of curvature of the rounded corners 519 d is equal to or more than half the volume average particle diameter of the toner particles, but the present invention is not limited thereto. For example, the radius of curvature of the rounded corners 519d may also be smaller than half the volume average particle diameter of the toner particles.

In the case where the radius of curvature of the rounded corners is less than half the volume average particle diameter of the toner particles, when the toner particles contact the rounded corners, sometimes the rounded corners are intruded into the toner particles and the Local concentration of toner particles. In contrast, as in the above-mentioned embodiment, when the radius of curvature of the rounded corners 519d is equal to or more than half the volume average particle diameter of the toner particles, there is no fear that the rounded corners 519d will intrude into the toner particles. It acts on the toner particles dispersedly from the rounded corners 519d. Therefore, the above-described embodiment is more preferable from the viewpoint that deformation of toner particles and the like can be suppressed.

In addition, in the above-described embodiment, as shown in FIG. 8 , the depth of the concave portion 518 is not more than twice the volume average particle diameter of the toner particles, but the present invention is not limited thereto. For example, the depth of the concave portion 518 may be greater than twice the volume average particle diameter of the toner particles.

When the depth of the concave portion 518 is less than twice the volume average particle diameter of the toner particles, although there are many toner particles located between the developing roller 510 and the restricting blade 560 in the concave portion 518, they all come into contact with the developer. At least one of the roller 510 and the regulating blade 560 is suitable for charging the toner particles. In this point, the above-described embodiment is more preferable. When the depth of the concave portion 518 is less than (one time) the volume average particle diameter of the toner particles, although there are more toner particles located between the developing roller 510 and the limiting blade 560 in the concave portion 518, they will all contact each other. To both the developing roller 510 and the regulating blade 560, it is more preferable.

In addition, as another preferred embodiment, the second embodiment and the fourth embodiment shown below can be mentioned (for convenience, the above-mentioned embodiment is hereinafter referred to as the first embodiment).

(second embodiment)

(Example of the structure of the developing roller 510 of the developing device of the second embodiment)

Here, an example of the structure of the developing roller 510 of the developing device of the second embodiment will be described with reference to FIG. 14 . Fig. 14 is equivalent to Fig. 8 and is a schematic view showing the cross-sectional shapes of protrusions and recesses in the second embodiment.

As can be seen from a comparison of FIGS. 8 and 14 , the difference between the developing roller 510 of the developing device of the second embodiment and the developing roller 510 of the developing device of the first embodiment lies in the protrusions.

As shown in FIG. 14 , the convex portion 1519 of the second embodiment has a rounded corner 1519d at its top end portion 1519a. The radius of curvature of the rounded corners 1519d is set at half or more of the volume average particle diameter (7 μm) of the toner particles.

The convex part 1519 has a side surface 1519b connected to the tip part 1519a. In this side surface 1519b, the portion from the lower portion 1519c of the convex portion toward the tip portion 1519a is flat. As shown in FIG. 14 , the side surface 1519b is an inclined surface connected to the flat bottom surface 1518c of the concave portion 1518 and inclined relative to the bottom surface 1518c. In addition, the inclination angle (the angle represented by the symbol β in FIG. 14 ) of the side surface 1519b with respect to the bottom surface 1518c of the concave portion 1518 is 45 degrees or less, and in this embodiment, the inclination angle is 45 degrees. In this embodiment, as shown in FIG. 14 , the cross-sectional shape of the fillet 1519d is an arc connecting two side surfaces 1519b. In this case, the aforementioned radius of curvature has the same magnitude as the radius of the arc. In addition, the height of the convex portion 1519 (the depth of the concave portion 1518 ) is not more than twice the volume average particle diameter (7 μm) of the toner particles.

In addition, the developing roller 1510 having the convex portion 1519 having a rounded corner 1519d at least at its tip end portion 1519a formed on its surface by the aforementioned manufacturing method (roll forming process), and the rounded corner The curvature radius of 1519d is more than half of the volume average particle diameter of the toner particles.

(Effectiveness of the developing device of the second embodiment)

As described above, the toner particle carrying roller (developing roller 510) of the developing device of the second embodiment has the convex portion 1519 which, as shown in FIG. The radius of curvature of the rounded corners 1519d is not less than half of the volume average particle diameter of the toner particles. Deformation and the like of the toner particles can thereby be suppressed. Detailed description will be given below.

When protrusions are formed on the surface of the developing roller 510 , a force may locally act from the protrusions to the toner particles due to the shape of the protrusions. For example, when the tip of the convex portion is relatively sharp, when the tip contacts a toner particle, force may be concentrated locally on the toner particle from the tip. In this way, when a force is concentrated locally on the toner particles from the convex portion, the toner may be deformed or the toner particles may be broken due to the force.

On the contrary, as shown in this embodiment, the convex portion 1519 has a rounded corner 1519d at least at the tip portion 1519a, and the radius of curvature of the rounded corner 1519d is equal to or more than half the volume average particle diameter of the toner particles. , when the rounded corners 1519d contact the toner particles, force is dispersedly acted on the toner particles from the convex portion 1519 (the rounded corners 1519d). Therefore, according to the developing roller 510 of this embodiment, it is possible to suppress the locally concentrated force from the convex portion 1519 on the toner particles, and to suppress the deformation of the toner particles due to the force.

(third embodiment)

(Structural Example of the Developing Roller 510 of the Developing Device of the Third Embodiment)

Here, a structural example of the developing roller 510 of the developing device of the third embodiment will be described with reference to FIGS. 15 to 17 . FIG. 15 is a schematic perspective view of the developing roller 510 . FIG. 16 is a schematic front view of the developing roller 510 . FIG. 17 is a schematic view showing the cross-sectional shape of the concave portion 2516 provided on the surface of the developing roller 510 , which shows a cross section along the direction indicated by symbol X or symbol Y in FIG. 16 . In addition, in FIGS. 15 to 17 , the proportions of the recessed portion 2516 and the like are different from the actual ones in order to facilitate understanding of the drawings.

The developing roller 510 of the developing device according to the third embodiment is a member made of aluminum alloy, iron alloy, etc., carries the toner T on its surface and transports it to a developing position facing the photoreceptor 20 .

As shown in FIGS. 16 and 17, in order to properly carry the toner on the surface of the developing roller 510, a concave portion 2516 and a non-recessed portion 2519 are provided on the central portion 2510a of the surface (both the concave portion 2516 and the non-recessed portion 2519 have function of the toner carrying portion carrying the toner). In this embodiment, the recessed part 516 and the non-recessed part 519 formed in the center part 510a of the surface of the developing roller 510 by the above-mentioned roll forming process are demonstrated.

The concave portion 2516 is a portion sunk in the central portion 510 a of the surface of the developing roller 510 , and has a flat bottom surface 2517 and side surfaces 2518 adjacent to the bottom surface.

In this embodiment, as shown in FIG. 17 , the opening width and depth of the concave portion 2516 are approximately 80 μm and 7 μm, respectively. In addition, the groove angle of the concave portion 2516 (the angle indicated by the symbol α in FIG. 17 ) is about 90 degrees. In addition, a rounded corner is provided at the boundary between the bottom surface 2517 and the side surface 2518, and the radius of curvature R of the rounded corner is equal to the volume average of the toner T (in this embodiment, the toner T is granular). More than half of the particle diameter (approximately 7 μm in this embodiment).

The non-recessed portion 2519 is a flat surface located at the highest position in the surface central portion 510 a of the developing roller 510 . As shown in FIG. 17 , the non-recessed portion 2519 adjoins the side surface 2518 at a position opposite to the bottom surface 2517 (opening side of the concave portion 2516 ). In addition, a rounded corner is provided at the boundary between the non-recessed portion 2519 and the side surface 2518 , and the radius of curvature R of the rounded corner is equal to or more than half of the volume average particle diameter of the toner T.

In this embodiment, as shown in FIG. 15 and FIG. 16 , the concave portion 2516 formed in the center portion 510a of the surface of the developing roller 510 by roll forming is formed into two spiral grooves with different winding directions (hereinafter, the spiral groove One of the grooves is called a first groove 2516a, and the other one is called a second groove 2516b). That is, in FIG. 16 , the recesses 2516 arranged in the cross section in the X direction belong to the first groove 2516 a, and the recesses 2516 arranged in the cross section in the Y direction belong to the second groove 2516 b. Here, as shown in FIG. 16 , the acute angles formed by the longitudinal direction of the first groove 2516 a and the second groove 2516 b and the axial direction of the developing roller 510 are each about 45 degrees. In addition, the helical pitches of the first groove 2516a and the second groove 2516b (the length indicated by the symbol L in FIG. 17 ) are all at equal intervals.

In the present embodiment, two spiral grooves whose winding directions are different from each other are formed on the surface central portion 510 a of the developing roller 510 as the concave portion 2516 , but the present invention is not limited thereto. For example, only one of the first groove 2516a and the second groove 2516b may be provided.

In addition, in order to realize the developing roller 510 of this embodiment, as the round dies 650 and 652 used in the through-type roll forming process, a die (for example, a round die) may be used in which the protrusions 650a, The edge portion of 652a has rounded corners with a radius of curvature larger than half the volume average particle diameter of the toner.

(Effectiveness of the developing device in the third embodiment)

As described above, the developing roller 510 of the present embodiment has on its surface a concave portion 2516 having a flat bottom surface 2517 and a side surface 2518 adjacent to the bottom surface, and a curvature is provided at the boundary between the bottom surface and the side surface. The radius R is rounded at half or more of the volume average particle diameter of the toner. Accordingly, it is possible to realize a developing roller capable of appropriately suppressing toner stagnation.

That is, as described above, in order to properly carry the toner, the surface of the developing roller 510 is provided with a concave portion 2516 having a flat bottom surface 2517 and a side surface 2518 adjacent to the bottom surface.

However, conventionally, a corner is provided at the boundary portion between the bottom surface 2517 and the side surface 2518 , so toner, particularly powdery toner, accumulates at the boundary portion. Here, this problem will be described with reference to FIG. 18 . FIG. 18 is an explanatory view for explaining a problem occurring in the recessed portion 2516 included in the conventional example of the developing roller 510 .

As shown in FIG. 18, when the boundary between the flat bottom surface 2517 of the concave portion 2516 and the side surface 2518 adjacent to the bottom surface has an angle, since the toner, especially powdery toner The toner rotates in the concave portion 2516 and does not come into contact with the toner having a relatively large particle size (hereinafter referred to as large particle size toner), so it cannot be discharged through the large particle size, and as a result stays in the concave portion 2516 .

However, the concave portion 2516 of the developing roller 510 in this embodiment can solve the above problems. This will be described with reference to FIG. 19 . FIG. 19 is an explanatory view for explaining the effectiveness of the recessed portion 2516 included in the developing roller 510 of this embodiment.

As shown in FIG. 19 , a rounded corner is provided at the boundary between the bottom surface 2517 and the side surface 2518 of the concave portion 2516 , and the radius of curvature R of the rounded corner is not less than half of the volume average particle diameter of the toner. With the concave portion 2516 of this structure, most of the large-diameter toner rotates while contacting the boundary portion, and therefore, the small toner can be appropriately discharged to the concave portion by the large-particle-diameter toner. 2516 exterior. Thereby, it is possible to appropriately suppress the stagnation of the toner.

In the present embodiment, as shown in FIG. 17 , the boundary portion between the side surface 2518 adjacent to the flat bottom surface 2517 provided in the concave portion 2516 and the non-recessed portion 2519 adjacent to the side surface is provided with a radius of curvature R in the toner. Rounded corners that are more than half of the volume average particle diameter, but not limited to. For example, in FIG. 17 , there may be a corner at the boundary between the non-recessed portion 2519 and the side surface 2518 . However, in this case, stress acts locally on the toner from the corners, and deformation of the toner may occur due to the stress.

On the other hand, when a rounded corner having a curvature R equal to or more than half the volume average particle diameter of the toner is provided at the boundary portion between the side surface 2518 and the non-recessed portion 2519, the toner will act on the boundary portion. The force is dispersed so that the deformation of the toner can be suppressed. In this point, this embodiment is more preferable.

(Other concave shapes)

In the above, as a concave portion that appropriately suppresses the stagnation of toner, a flat bottom surface 2517 and a side surface 2518 adjacent to the bottom surface are provided, and a radius of curvature R larger than the volume of the toner is provided at the boundary between the bottom surface and the side surface. The rounded concave portion of half the average particle diameter (this example related to the second embodiment) has been described. However, this embodiment is an example of the concave portion that appropriately suppresses stagnation of toner, and other examples may be considered. In this section, a recess having a shape different from this example (an example related to the second embodiment) will be described. FIG. 20 corresponds to FIG. 16 and is a schematic front view of a developing roller 510 according to this modified example. FIG. 21 is a schematic view showing a cross-sectional shape of a concave portion 2580 in this modified example, and shows a cross-section along a direction indicated by a symbol X or a symbol Y in FIG. 20 . In addition, in FIG. 20 and FIG. 21 , the proportions of the recessed portion 2580 and the like are different from the actual one.

The concave portion 2580 of this modified example has planar inclined portions (hereinafter referred to as planar inclined portions) 2581a, 2582a in the center portion 510a of the surface of the developing roller 510, and has a first side surface 2581 and a second side surface 2582 facing each other. .

In this modified example, there is no portion corresponding to the non-recessed portion 2519 on the surface central portion 510 a of the developing roller 510 . As shown in FIG. 21 , the concave portion 2580 is adjacent to another concave portion 2583 next to it. That is, the first side surface 2581 and the third side surface 2584 are adjacent to each other on the upper portion (opening side) of the concave portion 2580 and the other concave portion 2583 . The other recess 2583 has a third side 2584 and a fourth side 2585 facing each other, and like the recess 2580, the third side 2584 and the fourth side 2585 have planar slopes 2584a, 2585a, respectively.

In this embodiment, as shown in FIG. 21 , the opening width and depth of the concave portion 2580 are approximately 80 μm and 7 μm, respectively. In addition, the groove angle (angle indicated by symbol α in FIG. 21 ) of the concave portion 2580 is about 110 degrees. In addition, a rounded corner is provided at the boundary between the first side surface 2581 and the second side surface 2582 , and the radius of curvature R of the rounded corner is not less than half of the volume average particle diameter of the toner particles.

In addition, the boundary portion between the first side surface 2581 and the third side surface 2584 is also provided with a rounded corner having a radius of curvature R equal to or more than half the volume average particle diameter of the toner, but the present invention is not limited thereto. For example, in FIG. 21 , the boundary between the first side 2581 and the third side 2584 may have a corner. However, from the viewpoint of suppressing the deformation of the toner, the embodiment of this modified example is more preferable.

In addition, in this embodiment, as shown in FIG. 20 and FIG. 21 , the concave portion 2580 formed on the central portion 510 a of the surface of the developing roller 510 is the same as in this embodiment, and the first grooves with different winding directions are formed. 2580a and a second groove 2580b. That is, in FIG. 20 , the recesses 2580 arranged on the cross section in the X direction belong to the first groove 2580 a, and the recesses 2580 arranged on the cross section in the Y direction belong to the second groove 2580 b.

In addition, here, as shown in FIG. 20 , the acute angles formed by the longitudinal direction of the first groove 2580 a and the second groove 2580 b and the axial direction of the developing roller 510 are each about 45 degrees. In addition, the helical pitches of the first groove 2580a and the second groove 2580b (the length indicated by the symbol L in FIG. 21 ) are all at equal intervals.

In addition, in order to realize the developing roller 510 in this modified example, as in the present embodiment, as the round dies 650 and 652 used for the flow-through roll forming process, the following dies (for example, rounded corner dies) may be used, The mold has rounded corners with a radius of curvature greater than half the volume average particle diameter of the toner at the edge portions of the convex portions 650a, 652a.

(fourth embodiment)

(Structural Example of the Developing Roller 510 of the Developing Device of the Fourth Embodiment)

Here, a configuration example of the developing roller 510 of the developing device according to the fourth embodiment will be described with reference to FIGS. 22 to 25 . FIG. 22 is a schematic perspective view of the developing roller 510 . FIG. 23 is a schematic front view of the developing roller 510 . FIG. 24 is an enlarged view of the central portion 510 a of the developing roller 510 . FIG. 25 is a schematic diagram showing the shapes of the convex portion 3512, the concave portion 3515, and the like, and the upper diagram of FIG. 25 schematically shows an enlarged view shown in FIG. 24 . In addition, the lower diagram of FIG. 25 shows the cross-sectional shapes of the convex portion 3512, the concave portion 3515, and the like. In addition, in FIG. 22 , FIG. 23 , and FIG. 25 , the proportions of the convex portion 3512 and the like are different from the actual ones in order to make the drawings easier to understand.

The developing roller 510 of the developing device of the fourth embodiment carries the toner T and conveys it to a developing position opposed to the photoreceptor 20 . The developing roller 510 is a member made of aluminum alloy, iron alloy, or the like.

As shown in FIGS. 23 to 25, in order to properly carry the toner on the developing roller 510, a convex portion 3512, a side portion 3514, and a concave portion 3515 are provided on the surface of the central portion 510a (in addition, the convex portion 3512, the side portion 3514 and the concave portion 3515 function as a toner carrying portion for carrying toner).

The convex portion 3512 is the highest portion in the central portion 510a, and has a square planar shape as shown in the upper diagram of FIG. 25 . The length L1 of one side of the square convex portion 3512 (see the lower diagram of FIG. 25 ) is about 28 μm.

In addition, the value of the ten-point average roughness Rz (JIS B 0601-1994 standard) of the convex portion 3512 depends on which direction the direction of the average line of the roughness curve is set when the ten-point average roughness Rz is determined. big difference. More specifically, when the direction of the average line is along the axial direction of the developing roller 510, the ten-point average roughness Rz of the convex portion 3512 has the largest value, which is about 2 μm. When the direction of the average line is along the circumferential direction of the developing roller 510, the ten-point average roughness Rz of the convex portion 3512 has the smallest value, which is about 0.5 μm. That is, the surface of the convex portion 3512 is rough in the axial direction and hardly rough in the circumferential direction (the vertical lines observed in the convex portion 3512 shown in FIG. 24 indicate the above).

The side portion 3514 is an inclined surface connecting the convex portion 3512 and the concave portion 3515 , as shown in the upper diagram of FIG. 25 , four side portions 3514 are provided corresponding to each side of the square convex portion 3512 . The inclination angle of the side portion 3514 is about 45 degrees as shown in the lower diagram of FIG. 25 .

As shown in FIGS. 22 to 25 , on the surface of the central portion 510 a of the developing roller 510 , a plurality of convex portions 3512 and (groups of) four side portions 3514 are regularly arranged in a mesh shape. In addition, the pitch P (see the lower diagram of FIG. 25 ) of the protrusions 3512 is about 80 μm.

The concave portion 3515 is the lowest part of the central portion 510a. As shown in FIG. 22 to FIG. 25, the concave portion 3515 surrounds the convex portion 3512 and the four side portions 3514, and is regularly formed in a net shape. The concave portion 3515 is formed in a spiral shape, and the acute angle formed between the longitudinal direction (the direction is indicated by a symbol X and a symbol Y in FIG. 25 ) and the axial direction of the developing roller 510 is about 45 degrees. In addition, the width (horizontal length) L2 (see the lower diagram of FIG. 25 ) of the concave portion 3515 is about 28 μm.

In addition, the depth D of the concave portion 3515 (the length from the convex portion 3512 to the concave portion 3515 in the radial direction of the developing roller 510 , see the lower diagram of FIG. 25 ) is about 12 μm. In addition, in the present embodiment, since the toner T is in the form of particles, and the volume average particle diameter of the toner T is about 7 μm, the depth D of the concave portion 3515 is equal to or greater than the volume average particle diameter and within the volume average particle diameter. less than twice the average particle size.

In addition, unlike the case of the convex portion 3512 described above, the value of the ten-point average roughness Rz of the concave portion 3515 is almost the same regardless of the direction of the average line. This value is about 0.5 μm. Thus, the maximum value (0.5 μm) of the ten-point average roughness Rz of the concave portion 3515 is smaller than the maximum value (2 μm) of the ten-point average roughness Rz of the convex portion 3512 . And, the maximum value of the ten-point average roughness Rz of the convex portion 3512 is not more than the volume average particle diameter of the toner T.

In addition, electroless Ni—P plating is performed on the surface of the central portion 510 a having the above-mentioned convex portion 3512 , side portion 3514 , and concave portion 3515 .

In addition, such a developing roller 510 can be manufactured as follows by the method described in the manufacturing method of the developing roller 510 .

That is, as shown in FIG. 13D , although centerless grinding is performed on the surface of the pipe material 600 into which the flange 604 is pressed, in this centerless grinding, the pipe material is clamped by a plurality of rotating grindstones. Grinding is performed in the circumferential direction by the grindstone. Therefore, the vertical lines in the circumferential direction are generated on the surface of the pipe material 600, and the ten-point average roughness Rz in the axial direction is larger than the ten-point average roughness Rz in the circumferential direction.

Centerless grinding is performed over the entire surface of the surface. When the direction of the average line of the roughness curve when calculating the ten-point average roughness Rz is set as the direction along the axial direction, ten points of the entire surface after centerless grinding The point average roughness Rz has a value of approximately 2 μm, and when the direction of the average line is defined as a direction along the circumferential direction, the ten point average roughness Rz value of the entire surface is approximately 0.5 μm. In addition, the ten-point average roughness Rz of the groove formed by the through-roll forming process (that is, the portion corresponding to the concave portion 3515 and the side portion 3514, see the lower diagram of FIG. 25 ) is also about 0.5 μm.

(Effectiveness of the developing device of the fourth embodiment)

As described above, the developing roller 510 of the fourth embodiment has the concave portions 3515 and the convex portions 3512 regularly arranged on its surface, and the maximum value (0.5 μm) of the ten-point average roughness Rz of the concave portions 3515 is larger than that of the ten-point average roughness Rz of the convex portions 3512. The maximum value (2 μm) of the average roughness Rz is small. Thereby, occurrence of shading unevenness in the toner image can be suppressed.

That is, as described above, in the state where the developing roller 510 faces the photoreceptor 20, the latent image carried on the photoreceptor 20 is developed by the toner carried on the surface of the developing roller 510, but sometimes The distance between the toner carried by the concave portion 3515 of the developing roller 510 and the latent image carried by the photoreceptor 20 is greater than the distance between the toner carried by the convex portion 3512 and the latent image.

In this case, then, the ratio of the amount of toner reaching the photoreceptor 20 relative to the amount of toner leaving the surface of the developing roller 510 (either the concave portion 3515 or the convex portion 3512 ) is greater in the case of the concave portion 3515 than in the case of the convex portion 3512. is smaller, therefore, the density of the toner image formed on the photoreceptor 20 by the toner carried on the concave portion 3515 is higher than that of the toner image formed on the photoreceptor 20 by the toner carried on the convex portion 3512 The density of the toner image is light, and uneven shading may occur in the toner image.

In contrast, in the developing roller 510 of the fourth embodiment, since the maximum value of the ten-point average roughness Rz of the concave portion 3515 is smaller than the maximum value of the ten-point average roughness Rz of the convex portion 3512 (that is, the concave portion 3515 is smooth and the convex portion 3512), therefore, when the latent image is developed, the amount of toner leaving the concave portion 3515 is larger than the amount of toner leaving the convex portion 3512. That is, according to the developing roller 510 of this embodiment, in the concave portion 3515 where the ratio of the amount of toner reaching the photoreceptor 20 to the amount of toner leaving the surface of the developing roller 510 is relatively small, the amount of toner leaving the surface (the concave portion 3515 ) can be increased. In the convex portion 3512 where the ratio is relatively large, the amount of toner leaving the surface (convex portion 3512) can be reduced, and therefore, the amount of toner reaching the photoreceptor 20 after leaving the concave portion 3515 can be reduced. This corresponds to the amount of toner reaching the photoreceptor 20 after leaving the convex portion 3512 .

Therefore, the density of the toner image formed on the photoreceptor 20 by the toner carried on the concave portion 3515 is higher than the density of the toner image formed on the photoreceptor 20 by the toner carried on the convex portion 3512. The density of the toner image is light, so that the problem of unevenness in gradation in the toner image can be suppressed.

(Other embodiments related to the fourth embodiment)

In the above, when the direction of the average line of the roughness curve when calculating the ten-point average roughness Rz is defined as the direction along the axial direction of the developing roller 510, the ten-point average roughness Rz of the convex portion 3512 is the largest, but not limited to this. For example, the mean line may be at the maximum when the direction of the average line is set to be along the circumferential direction of the developing roller 510 .

In addition, in the above-described embodiment, when the direction of the average line of the roughness curve when calculating the ten-point average roughness Rz is defined as a direction along the circumferential direction of the developing roller 510, the ten-point average roughness Rz of the convex portion 3512 minimum, but not limited to. For example, the mean line may be maximized when the direction of the average line is set along the axial direction of the developing roller 510 .

When the developing roller 510 rotates around the central axis, the toner carried on the surface of the central portion 510a of the developing roller 510 moves in the circumferential direction of the developing roller 510, but when the direction of the mean line is set to be along the circumference If the ten-point average roughness Rz of the convex portion 3512 is relatively large, the toner moving in the circumferential direction may stop on the convex portion 3512 .

Therefore, when the direction of the average line is set as the direction along the circumferential direction of the developing roller 510, if the ten-point average roughness Rz of the convex portion 3512 is minimized, the occurrence of the above phenomenon can be appropriately suppressed, and the adjustment can be improved. Rotation of toner. From this point of view, the above-described embodiment is more preferable.

In addition, in the above-described embodiment, the maximum value of the ten-point average roughness Rz of the convex portion 3512 is not more than the volume average particle diameter of the toner, but the present invention is not limited thereto. The ten-point average roughness Rz of the convex portion 3512 is The maximum value may also be larger than the volume average particle diameter of the toner.

However, the above-described embodiment is more preferable in terms of making it difficult for the toner to fit into the convex portion 3512 and further improving the rotatability of the toner.

(fifth embodiment)

(Relationship between the convex portion of the developing roller provided in the developing device of the fifth embodiment and the wall area of the toner supply roller provided in the developing device)

As described above, the developing roller 510 is supplied with toner from the toner supply roller 550 , and the toner remaining after developing the latent image on the photoreceptor 20 is peeled off by the toner supply roller 550 . At this time, the toner contained in the holes 550 c (see FIGS. 26 to 28 ) of the toner supply roller 550 is mainly supplied to the surface of the developing roller 510 and remains in the wall area surrounding the holes 550 . The toner on the surface of the developing roller 510 connected to 550d (see FIGS. 26 to 28 ) is peeled off. In addition, a large number of square protrusions 4512 are formed on the surface of the developing roller 510 . Since the latent image on the photoreceptor 20 is developed by the toner carried on the opposite portion of the developing roller 510 , both the groove portion of the developing roller 510 and the convex portion 4512 need to carry toner.

However, when the developing roller 510 is in contact with the toner supply roller 550, if the wall region 550d of the toner supply roller 550 covers the entire surface of the convex portion 4512 of the developing roller 510, the convex portion 4512 covering the entire surface The toner on the surface is peeled off. Therefore, if the wall area 550d of the toner supply roller 550 covers the entire area of the surface of the convex portion 4512 of the developing roller 510, there will be a portion on the surface of the developing roller 510 where no toner is carried. When the toner image is not developed, unevenness in density occurs due to the generation of parts that are not developed into a toner image, or the generation of parts with relatively low density.

Therefore, in the developing device of the present embodiment, the average distance in the axial direction of the toner supply roller 550 between the openings of the holes 550 c of the toner supply roller 550 is larger than the top surface of the convex portion 4512 of the developing roller 510 . The axial maximum width of 4512a is small. This matter will be described with reference to FIG. 26 . FIG. 26 is a schematic diagram for explaining the effectiveness of the developing device of the fifth embodiment.

In the left figure of FIG. 26 , an enlarged schematic view of the cross section of the roller portion 550 a of the toner supply roller 550 is shown. Here, the distances in the axial direction of the toner supply roller 550 between the openings of the holes 550c of the toner supply roller 550 refer to, for example, distances indicated by symbols Dx1, Dx2, Dx3, and Dx4 in FIG. In addition, the average distance Dxave of this distance refers to: a plurality of (for example twenty) the average value of this distance Dx1, Dx2, ..., Dx20 (in Fig. 26, distance Dx1, Dx2, ..., Dx20 is The distances on the same straight line, but the distances Dx1, Dx2, ..., Dx20 do not necessarily need to be the distances on the same straight line). In the toner supply roller 550 of the present embodiment, the average distance Dxave is about 40 to 50 μm.

On the other hand, one of the top surfaces 4512a of the plurality of protrusions 4512 is shown in the right diagram of FIG. 26 . In the developing roller 510 of this embodiment, the maximum width in the axial direction of the top surface 4512 a of the convex portion 4512 (this maximum width is indicated by a symbol Wx in FIG. 26 ) is about 80 μm.

As described above, in the developing device according to the present embodiment, since the average distance Dxave is smaller than the maximum width Wx, there are advantages described below. That is, in this developing device, even if the wall region 550d between the openings of the hole 550c of the toner supply roller 550 is connected to the top surface 4512a of the convex portion 4512, it is possible to avoid the toner supply roller 550 in the axial direction of the toner supply roller 550. , the top surface 512a is completely covered by the wall region 550d (in the right diagram of FIG. 26 , an example of the part of the top surface 4512a not covered by the wall region 550d is indicated by oblique lines). Therefore, when the portion where the toner supply roller 550 contacts the developing roller 510 is separated from the toner supply roller 550 and the carried toner is charged by the regulating blade 560 and the layer thickness is restricted, the top surface of the convex portion 4512 4512a is properly loaded with toner.

Then, even if the toner is carried on a part of the top surface 4512a of the convex portion 4512, the toner carried on the top surface 4512a of the convex portion 4512 is piled up due to the restriction of the layer thickness by the regulating blade 560. Open evenly on the top surface 4512. In other words, the toner accumulated and carried on the top surface 4512a is diffused over a wide range of the top surface 4512a. Therefore, when the latent image is developed, it is possible to appropriately avoid density unevenness due to the occurrence of a portion that is not developed into a toner image or the generation of a portion with a relatively low density.

Next, referring to FIG. 27 , the relationship between the top surface 4512 a of the convex portion 4512 and the wall region 550 d in the circumferential direction of the developing roller 510 and the toner supply roller 550 will be considered. FIG. 27 is a schematic diagram for explaining the effectiveness of the developing device of the fifth embodiment.

In the left figure of FIG. 27 , as in FIG. 26 , there is shown an enlarged cross-sectional view of the roller portion 550 a of the toner supply roller 550 . Here, the distances in the circumferential direction of the toner supply roller 550 between the openings of the holes 550c of the toner supply roller 550 are, for example, the distances indicated by symbols Dy1, Dy2, and Dy3 in FIG. The average distance Dyave is the average value of multiple (eg 20) distances Dy1, Dy2, . . . , Dy20. In the toner supply roller 550 of the present embodiment, the average distance Dyave is about 40 to 50 μm, which is the same as the aforementioned average distance Dxave.

On the other hand, in the right diagram of FIG. 27 , as in FIG. 26 , one of the top surfaces 4512 a of the plurality of protrusions 4512 is shown. In the developing roller 510 of the present embodiment, the maximum width in the circumferential direction of the top surface 4512a of the convex portion 4512 (this maximum width is indicated by symbol Wy in FIG. 27 ) is about 80 μm as the above-mentioned maximum width Wx.

Then, even for the circumferential direction, if the average distance Dyave and the maximum width Wy satisfy a relationship in the circumferential direction of the toner supply roller 550 such that the wall region 550d can be prevented from completely covering the top surface 4512a, then even The wall region 550d between the openings of the hole 550c of the toner supply roller 550 is connected to the top surface 4512a of the convex portion 4512, which can also produce the effect that when the latent image is developed, it is possible to properly avoid the A portion that is not developed into a toner image or a portion that has a relatively low density results in uneven density.

Considering this relationship here, the circumferential direction is somewhat different from the axial direction. That is, in this embodiment, as described above, a peripheral speed difference is provided between the toner supply roller 550 and the developing roller 510, and the surface moving speed of the toner supply roller 550 when the toner supply roller 550 rotates is It is about 1.5 times the surface moving speed of the developing roller 510 when the developing roller 510 rotates. In this case, for example, while the surface of the toner supply roller 550 advances by the average distance Dyave, the surface of the developing roller 510 advances only by the average distance Dyave divided by the toner supply roller 550. The distance obtained by the ratio R (ie, 1.5) of the surface moving speed of the developing roller 510 to the surface moving speed of the developing roller 510 . Therefore, with respect to the circumferential direction, when the average distance Dyave is divided by the ratio R (ie, 1.5) of the surface moving speed of the toner supply roller 550 to the surface moving speed of the developing roller 510 When the maximum value Wy in the circumferential direction of the top surface 4512a is small, the effect is produced.

In this embodiment, the value obtained by dividing the average distance Dyave by the ratio R of the surface moving speed of the toner supply roller 550 to the surface moving speed of the developing roller 510 (ie, 1.5) is about 26 to 33 μm, which is higher than the above-mentioned value. The maximum width Wy (about 80 μm) is small. Therefore, even if the wall region 550d between the openings of the hole 550c of the toner supply roller 550 is connected to the top surface 4512a of the convex portion 4512, the top surface 4512a can be avoided in the circumferential direction of the toner supply roller 550. is completely covered by the wall region 550d (in the right diagram of FIG. 27 , an example of the part of the top surface 4512a not covered by the wall region 550d is indicated by oblique lines). Therefore, when the latent image is developed, it is possible to appropriately avoid density unevenness due to the occurrence of a portion that is not developed into a toner image or the generation of a portion with a relatively low density.

In addition, as shown in FIG. 28 , the developing device of the present embodiment is formed such that when the convex portion 4512 of the developing roller 510 contacts the wall region 550d of the toner supply roller 550, at least the top surface of the convex portion 4512 A portion of the top surface 4512a protrudes beyond the wall region 550d surrounded by the plurality of holes 550c (in FIG. 28, the portion of the top surface 4512a protruding beyond the wall region 550d is indicated by oblique lines).

Therefore, in this developing device, even if the wall region 550d between the openings of the hole 550c of the toner supply roller 550 is connected to the top surface 4512a of the convex portion 4512, the top surface 4512a can be more properly prevented from being damaged. The wall region 550d is completely covered. Therefore, when developing the latent image, it is possible to more appropriately avoid density unevenness due to the generation of parts that are not developed into toner images or the generation of parts with relatively low density.

28 is a schematic diagram for explaining the effectiveness of the developing device according to the fifth embodiment, showing a state where the convex portion 4512 of the developing roller 510 is in contact with the wall region 550d of the toner supply roller 550 .

In addition, as described above, the layer thickness of the toner particles carried on the surface of the developing roller 510 is restricted by restricting the flat surface that the blade 560 has. Therefore, the toner particles carried on the surface of the developing roller 510 are not completely swept off by the restricting blade 560, and the toner particles supplied to only a part of the top surface of the convex portion 4512 can be moved by the restricting blade 560. The top surface of the convex portion 4512 is evenly spread out.

(Structure of image forming system etc.)

Next, an embodiment of an image forming system as an example of an embodiment of the present invention will be described with reference to the drawings.

FIG. 29 is an explanatory diagram showing the external configuration of the image forming system. The image forming system 700 includes a computer 702 , a display device 704 , a printer 706 , an input device 708 , and a reading device 710 . In this embodiment, the computer 702 is accommodated in a mini tower (MiniTower) type housing, but it is not limited to this. The display device 704 generally uses a CRT (Cathode Ray Tube, cathode ray tube), a plasma display or a liquid crystal display, etc., but is not limited thereto. As the printer 706, the printers described above are used. The input device 708 uses a keyboard 708A and a mouse 708B in this embodiment, but is not limited thereto. As the reading device, the flexible disk drive unit 710A and the CD-ROM drive unit 710B are used in this embodiment, but the present invention is not limited thereto. For example, other devices such as MO (Magneto Optical, magneto-optical disk) disk drives and DVD (Digital Versatile Disk, multi-purpose digital disk) may also be used.

FIG. 30 is a block diagram showing the configuration of the image forming system shown in FIG. 29 . The casing housing the computer 702 is also provided with an internal memory 802 such as RAM and an external memory such as a hard disk drive unit 804 .

In the above description, an example in which the printer 706 is connected to the computer 702, the display device 704, the input device 708, and the reading device 710 to form an image forming system has been described, but the present invention is not limited thereto. For example, the image forming system may be composed of the computer 702 and the printer 706 , and may not include any of the display device 704 , the input device 708 , and the reading device 710 .

In addition, for example, the printer 706 may have a part of the respective functions or structures of the computer 702 , the display device 704 , the input device 708 , and the reader device 710 . As an example, the printer 706 may include: an image processing unit that performs image processing; a display unit that performs various displays; and a recording medium loading unit for loading a recording medium recording image data captured by a digital camera or the like.

The image forming system realized as described above is superior to conventional systems as a whole.

Claims (6)

1. a developing apparatus has toner-particle bearing roller, and this toner-particle bearing roller carries toner-particle in its surface, and develops to being carried on as the sub-image on the supporting body by this toner-particle,

Described toner-particle bearing roller has and is arranged on described lip-deep protuberance, and this protuberance possesses the end face with flat, and the width of this end face is more than the volume average particle size of described toner-particle, wherein,

Described protuberance has the side that links to each other with described end face,

Connecting portion in described end face and described side is formed with fillet.

2. developing apparatus as claimed in claim 1, also has layer-thickness restriction member, this layer-thickness restriction member contacts with this toner-particle bearing roller in the gamut of the other end from an axial end of described toner-particle bearing roller, be used to limit the bed thickness that is carried on the toner-particle on this toner-particle bearing roller

Described layer-thickness restriction member contacts with described toner-particle bearing roller by plane that this layer-thickness restriction member has and limits described bed thickness.

3. developing apparatus as claimed in claim 1 or 2, wherein, the radius-of-curvature of described fillet is volume average particle size over half of described toner-particle.

4. developing apparatus as claimed in claim 1 or 2, wherein,

Be provided with spiral helicine slot part on described surface, this slot part tilts with respect to the axial and circumferencial direction of described toner-particle bearing roller, and in described axial equal intervals,

Described slot part forms two types by the angle difference that makes described inclination,

Described protuberance is surrounded by described two types described slot part,

The degree of depth of described slot part is below the twice of volume average particle size of described toner-particle.

5. developing apparatus as claimed in claim 1 or 2, wherein,

Be provided with spiral helicine slot part on described surface, this slot part tilts with respect to the axial and circumferencial direction of described toner-particle bearing roller, and in described axial equal intervals,

Described slot part forms two types by the angle difference that makes described inclination,

Described protuberance is surrounded by described two types described slot part,

Described sub-image has and is formed on the point-like sub-image that is divided in the cancellate zone,

Described can be formed on as supporting body described axially on the grid of polytype spacing,

The long spacing of described slot part in the polytype spacing of the described described grid of gap ratio on axially is little.

6. an image processing system has developing apparatus, and this developing apparatus possesses:

Be used to carry the picture supporting body of sub-image; And

Toner-particle bearing roller, this toner-particle bearing roller carries toner-particle in its surface, and describedly develop to being carried on as the sub-image on the supporting body by this toner-particle, described toner-particle bearing roller has and is arranged on described lip-deep protuberance, this protuberance possesses the end face with flat, and the width of this end face is more than the volume average particle size of described toner-particle, wherein

Described protuberance has the side that links to each other with described end face,

Connecting portion in described end face and described side is formed with fillet.

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