JP2010230735A - Method for manufacturing developing roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a developing roller by which a lightweight roller can be manufactured. <P>SOLUTION: The method for manufacturing the developing roller includes a step of forming a prescribed irregular pattern on a first plate surface of a metal plate by press working, and a step of forming the metal plate like a cylinder by press working so that the first plate surface on which the irregular pattern has been formed may be an external surface and a pair of opposed end sides of the metal plate may approach. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a developing roller.

  Image forming apparatuses such as laser beam printers are already well known. Such an image forming apparatus includes, for example, an image carrier for carrying a latent image and a developer for conveying the developer to a position facing the image carrier by rotating in a state of carrying the developer. And a roller. When an image signal or the like is transmitted from an external device such as a host computer, the image forming apparatus forms an image by developing the latent image carried on the image carrier with the developer conveyed to the opposite position by the developing roller. Then, the image is transferred to a medium, and finally an image is formed on the medium. As shown in Patent Document 1, for example, a cylindrical roller is used as the developing roller.

JP 2007-233196 A

  However, when a solid cylindrical developing roller is used, the developing roller becomes heavy. For this reason, there is a problem that the weight of the entire image forming apparatus is increased or a load on a driving system for driving the developing roller is increased.

  An object of the present invention is to provide a method for producing a developing roller excellent in lightness.

  The developing roller manufacturing method according to the present invention includes a pattern forming step of forming a predetermined uneven pattern on a first plate surface of a metal plate by pressing, and the first plate surface on which the uneven pattern is formed is an outer surface. And a cylindrical processing step of forming the metal plate into a cylindrical shape by pressing so that a pair of edges of the metal plate face each other at a predetermined interval.

  According to the present invention, a hollow cylindrical roller can be formed by pressing a metal plate. Thereby, a lightweight roller can be manufactured compared with a solid cylindrical roller. In addition, in the present invention, since the metal plate is pressed after the predetermined uneven pattern is formed on the first plate surface of the metal plate, the degree of freedom of the uneven pattern formed on the metal plate is widened. . In the present invention, the pair of edges of the metal plate are opposed to each other at a predetermined interval without being in close contact with each other, so that a place for escape of compressed air can be ensured. Thereby, the vibration at the time of rotation can be prevented.

In the developing roller manufacturing method, the uneven pattern includes at least one of a linear pattern, a curved pattern, a polygonal pattern, and a circular pattern.
According to the present invention, since the concavo-convex pattern is formed by pressing before pressing the metal plate, for example, as the concavo-convex pattern, the width of the concavo-convex pattern that can be formed, such as a linear pattern, a curved pattern, a polygonal pattern, and a circular pattern Will spread. Of course, you may make it form the pattern which combined these patterns.

The developing roller manufacturing method further includes a welding step of connecting at least a part of the pair of end sides by welding.
According to the present invention, since a part of the pair of end sides is connected by welding, the positional relationship between the pair of end sides can be stabilized. Further, since only a part of the pair of end sides is welded, the escape space for the compressed air is ensured.

The developing roller manufacturing method described above further includes a coating step of coating a resin film on the first plate surface of the cylindrical metal plate.
According to the present invention, since the resin film is applied to the metal plate after being formed into a cylindrical shape, the resin film can be applied efficiently and uniformly.

The developing roller manufacturing method is characterized in that the pattern forming step presses a second plate surface of the metal plate opposite to the first plate surface.
According to the present invention, in the pattern formation step, the metal plate is pressed against the second plate surface opposite to the first plate surface, so that processing marks such as burrs remain on the first plate surface. Can be avoided as much as possible.

In the manufacturing method of the developing roller described above, the metal plate formed in a cylindrical shape includes an image carrier that carries a latent image, and a developing roller that is disposed to face the image carrier. Of these, it is used as the developing roller.
According to the present invention, since the metal plate formed in a cylindrical shape is used as the developing roller of the image forming apparatus, the lightness can be sufficiently exhibited. Further, since a gap is formed between the pair of edges of the metal plate, vibration can be prevented when the developing roller is rotated. As a result, the distance from the image carrier can be kept constant, and high-precision development can be performed.

FIG. 2 is a diagram illustrating main components constituting the image forming apparatus. It is a block diagram which shows a control unit. It is a conceptual diagram of a developing device. It is sectional drawing which showed the main components of the image development apparatus. It is a perspective schematic diagram of a developing roller. It is a front schematic diagram of a developing roller. It is a cross-sectional schematic diagram of a developing roller. It is a front view of a holder. It is the schematic diagram which showed the alternating voltage applied to a developing roller. It is a flowchart which shows the manufacturing process of a developing roller. It is a top view which shows the metal plate as a base material of a developing roller. It is process drawing for demonstrating the press work which forms an uneven | corrugated pattern in a metal plate. (A)-(c) is process drawing for demonstrating the press work of a metal plate. (A)-(c) is process drawing for demonstrating the press work of a metal plate. It is a perspective view of a developing roller. It is a schematic block diagram of a painting booth. FIG. 3A is a perspective view of a main part of the developing roller, and FIG. (A) is a principal part perspective view of a developing roller, (b) is a side view. (A) is a principal part perspective view of a developing roller, (b) is a side view. (A) is a principal part perspective view of a developing roller, (b) is a side view. (A)-(c) is a principal part top view of the metal plate which shows an expansion | deployment engaging part. (A), (c) is a figure which shows a joint, (b) is a top view of a metal plate. (A) is a figure which shows the joint of a developing roller, (b) is a top view of a metal plate. (A) is a figure which shows the joint of a developing roller, (b) is a top view of a metal plate. (A)-(c) is a figure for demonstrating the shape of a joint. (A) is shape explanatory drawing of a joint, (b) is effect | action explanatory drawing. It is a figure for demonstrating the shape of a joint. (A)-(c) is a figure for demonstrating the shape of a joint.

  Next, an outline of a laser beam printer (hereinafter also referred to as a printer) 10 as an example of the image forming apparatus will be described with reference to FIG. FIG. 1 is a diagram illustrating main components constituting the printer 10. In FIG. 1, the vertical direction is indicated by arrows. For example, the paper feed tray 92 is disposed at the lower part of the printer 10, and the fixing unit 90 is disposed at the upper part of the printer 10.

  As shown in FIG. 1, the printer 10 according to the present embodiment includes a charging unit 30, an exposure unit 40, and a YMCK along the rotation direction of a photoconductor 20 as an example of an image carrier for carrying a latent image. A developing unit 50, a primary transfer unit 60, an intermediate transfer member 70, and a cleaning unit 75; a secondary transfer unit 80; a fixing unit 90; A control unit 100 is provided for controlling these units and controlling the operation as a printer.

  The photoreceptor 20 has a cylindrical conductive substrate and a photosensitive layer formed on the outer peripheral surface thereof, and is rotatable around a central axis. In the present embodiment, the photoreceptor 20 is indicated by an arrow in FIG. Rotate clockwise.

  The charging unit 30 is a device for charging the photoconductor 20, and the exposure unit 40 is a device for forming a latent image on the photoconductor 20 charged by irradiating a laser. The exposure unit 40 includes a semiconductor laser, a polygon mirror, an F-θ lens, and the like, and charges the modulated laser based on an image signal input from a host computer (not shown) such as a personal computer or a word processor. The irradiated photoconductor 20 is irradiated.

  The YMCK developing unit 50 converts the latent image formed on the photoconductor 20 into toner as an example of a developer contained in the developing device, that is, black (K) toner contained in the black developing device 51, magenta development. An apparatus for developing using magenta (M) toner stored in the device 52, cyan (C) toner stored in the cyan developing device 53, and yellow (Y) toner stored in the yellow developing device 54. is there.

  The YMCK developing unit 50 can move the positions of the four developing devices 51, 52, 53, 54 by rotating with the four developing devices 51, 52, 53, 54 mounted. Yes. That is, the YMCK developing unit 50 holds the four developing devices 51, 52, 53, 54 by four holding portions 55a, 55b, 55c, 55d, and the four developing devices 51, 52, 53, 54 is rotatable around the central axis 50a while maintaining the relative position thereof. Each time image formation for one page is completed, it is selectively opposed to the photoconductor 20, and is formed on the photoconductor 20 with the toner accommodated in each developing device 51, 52, 53, 54. The latent images are developed sequentially. Each of the four developing devices 51, 52, 53, 54 described above is detachable from the holding portion of the YMCK developing unit 50. Details of each developing device will be described later.

  The primary transfer unit 60 is a device for transferring a single color toner image formed on the photoconductor 20 to the intermediate transfer body 70. When four color toners are sequentially transferred in a superimposed manner, the full color toner is transferred to the intermediate transfer body 70. An image is formed.

  This intermediate transfer body 70 is an endless belt in which a tin vapor deposition layer is provided on the surface of a PET film and a semiconductive paint is formed on the surface layer and laminated. The intermediate transfer body 70 is driven to rotate at substantially the same peripheral speed as the photoconductor 20.

The secondary transfer unit 80 is a device for transferring a single color toner image or a full color toner image formed on the intermediate transfer body 70 to a medium such as paper, film, or cloth.
The fixing unit 90 is a device for fusing a single-color toner image or a full-color toner image transferred onto a 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 rubber cleaning blade 76 that is in contact with the surface of the photoconductor 20. The cleaning unit 75 is disposed on the intermediate transfer body 70 by the primary transfer unit 60. After the toner image is transferred, the toner remaining on the photoreceptor 20 is scraped off and removed by the cleaning blade 76.

  As shown in FIG. 2, the control unit 100 includes a main controller 101 and a unit controller 102. An image signal and a control signal are input to the main controller 101, and in response to a command based on the image signal and the control signal. A unit controller 102 controls each of the units and forms an image.

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) are input to the main controller 101 of the printer 10 via the interface (I / F) 112, the unit controller 102 based on a command from the main controller 101. The photosensitive member 20 and the intermediate transfer member 70 are rotated by the control. The photoconductor 20 is sequentially charged by the charging unit 30 at the charging position while rotating.

  The charged area of the photoconductor 20 reaches an exposure position as the photoconductor 20 rotates, and a latent image corresponding to image information of the first color, for example, yellow Y, is formed in the area by the exposure unit 40. . In the YMCK developing unit 50, a yellow developing device 54 that contains yellow (Y) toner is located at a developing position facing the photoconductor 20.

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

  The yellow toner image formed on the photoconductor 20 reaches the primary transfer position as the photoconductor 20 rotates, and is transferred to 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 T (negative polarity in the present embodiment) is applied to the primary transfer unit 60. During this time, the photosensitive member 20 and the intermediate transfer member 70 are in contact with each other, and the secondary transfer unit 80 is separated from the intermediate transfer member 70.

  The above processing is sequentially executed for each developing device for the second color, the third color, and the fourth color, so that four color toner images corresponding to the respective image signals are transferred to the intermediate transfer member 70. It is transcribed and superimposed. As a result, a full color toner image is formed on the intermediate transfer member 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 to the medium by the secondary transfer unit 80. The medium is conveyed from the paper feed tray 92 to the secondary transfer unit 80 via the paper feed roller 94 and the registration roller 96. When performing the transfer operation, the secondary transfer unit 80 is pressed against the intermediate transfer body 70 and a secondary transfer voltage is applied.
The full color toner image transferred to the medium is heated and pressed by the fixing unit 90 and fused to the medium.

  On the other hand, after the primary transfer position has passed, the photosensitive member 20 is scraped off by the cleaning blade 76 supported by the cleaning unit 75 and the toner T adhering to the surface thereof is charged to form the next latent image. Prepare for. The toner T thus scraped off is collected by a residual toner collecting unit provided in the cleaning unit 75.

  Next, the configuration of the control unit 100 will be described with reference to FIG. 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 an image signal input from the host computer. The unit controller 102 is electrically connected to each unit (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) of the apparatus main body. Each unit is controlled based on a signal input from the main controller 101 while detecting a state of each unit by receiving a signal from a sensor included in them.

  The YMCK development unit drive control circuit 128 connected to the YMCK development unit 50 includes a voltage application unit 132. The voltage application unit 132 serves to apply an alternating voltage to the developing roller 510 and develop an alternating electric field between the developing roller 510 and the photoconductor 20 in order to develop the latent image with toner.

Next, the configuration of the developing device will be described.
FIG. 3 is a conceptual diagram of the developing device. FIG. 4 is a cross-sectional view showing the main components of the developing device. FIG. 5 is a schematic perspective view of the developing roller 510. FIG. 6 is a schematic front view of the developing roller 510. FIG. 7 is a schematic diagram showing a partial cross-sectional shape of the developing roller 510. FIG. 8 is a schematic view showing a state in which the developing roller 510 is assembled. Note that the cross-sectional view shown in FIG. 4 represents a cross-section obtained by cutting the developing device along a plane perpendicular to the longitudinal direction shown in FIG. 4, the vertical direction is indicated by arrows as in FIG. 1. For example, the central axis of the developing roller 510 is below the central axis of the photoconductor 20. Further, in FIG. 4, the yellow developing device 54 is shown in a state where the yellow developing device 54 is located at a developing position facing the photoconductor 20.

  The YMCK developing unit 50 includes a black developing device 51 containing black (K) toner, a magenta developing device 52 containing magenta (M) toner, a cyan developing device 53 containing cyan (C) toner, and a yellow ( Y) Although a yellow developing device 54 containing toner is provided, the configuration of each developing device is the same, so the yellow developing device 54 will be described below.

  The yellow developing device 54 includes a developing roller 510 as an example of a developer carrier, an upper seal 520, a toner container 530, a housing 540, a toner supply roller 550, a regulating blade 560, a holder 526, and the like.

  The developing roller 510 conveys the toner T to a facing position (developing position) facing the photoconductor 20 by rotating in a state where the toner T is carried. The developing roller 510 is formed in a cylindrical shape by pressing a metal plate such as a galvanized steel plate or a stainless steel plate. Thus, since the developing roller 510 is formed hollow, it is lighter than a solidly formed developing roller, and the burden required for driving is reduced as compared with the case where a solid developing roller is used. .

  In the developing roller 510, a pair of end surfaces of the pressed metal plate are slightly spaced apart, and a gap is formed between the end surfaces. The gap is formed, for example, in a straight line along the longitudinal direction of the developing roller 510. The shape of the gap is not limited to being formed in a straight line, and other shapes may be used. As shown in FIG. 7, in the present embodiment, the distance d1 between the end faces is formed to be about 0.01 mm to 0.09 mm.

  As shown in FIGS. 5 and 6, the developing roller 510 has a groove portion 512 as an example of a concave portion on the surface of the central portion 510 a in order to appropriately carry the toner T. In the present embodiment, as the groove portion 512, two kinds of groove portions 512 orthogonal to each other, that is, a first groove portion 512a and a second groove portion 512b are formed. The first groove portion 512 a is a groove portion formed along the longitudinal direction of the developing roller 510. The second groove portion 512b is a groove portion formed along the circumferential direction of the developing roller 510.

  As shown in FIGS. 5 and 6, the first groove portion 512a and the second groove portion 512b are regularly arranged on the surface of the central portion 510a of the developing roller 510 and intersect with each other to form a lattice shape. . Therefore, a large number of rectangular top surfaces 515 surrounded on all sides by the grooves 512 are formed on the mesh at the central portion 510a. Both ends in the longitudinal direction of the developing roller 510 are shaft portions 510b. As shown in FIG. 8, the shaft portion 510 b is rotatably supported by a developing roller support portion 526 b of a holder 526 via a bearing 576.

  As shown in FIG. 4, the developing roller 510 rotates in a direction (counterclockwise in FIG. 4) opposite to the rotation direction of the photoconductor 20 (clockwise in FIG. 4). In the present embodiment, the moving speed V of the surface of the developing roller 510 when the developing roller 510 rotates (that is, the linear velocity of the developing roller 510 on the surface of the developing roller 510) is, for example, 300 mm / s. Further, the moving speed of the surface of the photoconductor 20 when the photoconductor 20 rotates (that is, the linear velocity of the photoconductor 20 on the surface of the photoconductor 20) is, for example, 210 mm / s, and the developing roller 510 The peripheral speed ratio with respect to the photoreceptor 20 is about 1.4.

  Further, a gap exists between the developing roller 510 and the photoconductor 20 in a state where the yellow developing device 54 faces the photoconductor 20. That is, the yellow developing device 54 develops the latent image formed on the photoconductor 20 in a non-contact state. In the printer 10 according to the present embodiment, a jumping development method is used, and an alternating electric field is generated between the developing roller 510 and the photoconductor 20 when the latent image formed on the photoconductor 20 is developed. It is supposed to be formed.

  The housing 540 is manufactured by welding a plurality of integrally formed resin housing parts, that is, the upper housing part 542 and the lower housing part 544, and in order to accommodate the toner T therein. The toner container 530 is formed. The toner containing body 530 has two toner containing portions, that is, a first toner containing portion 530a and a second toner, by a partition wall 545 for dividing the toner T projected inwardly (in the vertical direction in FIG. 4) from the inner wall. It is divided into the accommodating portion 530b. The upper portions 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. However, when the YMCK developing unit 50 rotates, the toner accommodated in the first toner accommodating portion 530a and the second toner accommodating portion 530b is once collected on the upper communicating side of the developing position. When returning to the state shown in FIG. 4, the toners are mixed and returned to the first toner storage portion 530a and the second toner storage portion 530b. That is, when the YMCK developing unit 50 rotates, the toner T in the developing device is appropriately agitated.

  For this reason, in this embodiment, the toner container 530 is not provided with a stirring member, but a stirring member for stirring the toner T stored in the toner container 530 may be provided. As shown in FIG. 4, the housing 540 (that is, the first toner storage portion 530 a) has an opening 572 in the lower portion, and the developing roller 510 is provided so as to face the opening 572.

  The toner supply roller 550 is provided in the first toner storage portion 530a described above, supplies the toner T stored in the first toner storage portion 530a to the development roller 510, and remains on the development roller 510 after development. The toner T is peeled off from the developing roller 510. The toner supply roller 550 is made of polyurethane foam or the like, and is in contact with the developing roller 510 in an elastically deformed state. The toner supply roller 550 is disposed below the first toner storage portion 530a, and the toner T stored in the first toner storage portion 530a is transferred by the toner supply roller 550 below the first toner storage portion 530a. Supplied to the developing roller 510. The toner supply roller 550 is rotatable about a central axis, and the central axis is below the rotation central axis of the developing roller 510. Further, the toner supply roller 550 rotates in a direction (clockwise in FIG. 4) opposite to the rotation direction of the developing roller 510 (counterclockwise in FIG. 4).

  The upper seal 520 is in contact with the developing roller 510 along the axial direction thereof, allows the toner T remaining on the developing roller 510 after passing through the developing position to move into the housing 540, and the housing 540. The movement of the toner T inside the housing 540 is restricted. The upper seal 520 is a seal made of a polyethylene film or the like. The upper seal 520 is supported by an upper seal support portion 526a of a holder 526, which will be described later, and is provided so that its longitudinal direction is along the axial direction of the developing roller 510 (FIG. 11). The contact position where the upper seal 520 contacts the developing roller 510 is above the central axis of the developing roller 510.

  Further, a malt is formed between a surface of the upper seal 520 opposite to the contact surface 520b that contacts the developing roller 510 (this surface is also referred to as an opposite surface 520c) and the upper seal support portion 526a. An upper seal urging member 524 made of an elastic body such as a plane is provided in a compressed state. The upper seal urging member 524 presses the upper seal 520 against the developing roller 510 by urging the upper seal 520 toward the developing roller 510 with the urging force.

  The regulating blade 560 abuts against the developing roller 510 at the abutting portion 562a from one end to the other end in the axial direction of the developing roller 510 to regulate the layer thickness of the toner T carried on the developing roller 510, In addition, a charge is applied to the toner T carried on the developing roller 510. The regulation blade 560 includes a rubber part 562 and a rubber support part 564 as shown in FIGS. 4 and 9.

  The rubber part 562 is made of silicon rubber, urethane rubber, or the like, and is in contact with the developing roller 510. The rubber support portion 564 includes a thin plate 564a and a thin plate support portion 564b, and supports the rubber portion 562 at one end portion 564d in the short 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 a spring property. The thin plate 564a supports the rubber part 562 and presses the rubber part 562 against the developing roller 510 by the biasing force. The thin plate support portion 564b is a metal sheet metal disposed on the other end 564e in the short side direction of the rubber support portion 564, and the thin plate support portion 564b is a side of the thin plate 564a that supports the rubber portion 562. It is attached to the said thin plate 564a in the state which supported the edge on the opposite side.

  The regulation blade 560 is attached to the regulation blade support 526c in a state where both longitudinal ends 564c of the thin plate support 564b are supported by a regulation blade support 526c of a holder 526 described later.

  The end of the regulating blade 560 opposite to the thin plate support portion 564b side, that is, the tip 560a is not in contact with the developing roller 510, and is a portion separated from the tip 560a by a predetermined distance (that is, the contact portion 562a). ) Is in contact with the developing roller 510 with a width. In other words, the regulating blade 560 is not in contact with the developing roller 510 at the edge but is in contact with the antinode, and the flat surface of the regulating blade 560 comes into contact with the developing roller 510 to regulate the layer thickness. To do. Further, the regulating blade 560 is disposed so that its tip 560a faces the upstream side in the rotation direction of the developing roller 510, and is in contact with a so-called counter. The contact position where the regulating 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. Further, the regulation blade 560 exhibits a function of preventing leakage of the toner T from the toner container 530 by contacting the developing roller 510 along the axial direction thereof.

  An end seal (not shown) is provided on the outer side in the longitudinal direction of the rubber portion 562 of the regulating blade 560. The end seal is formed of a non-woven fabric, contacts the axial end of the developing roller 510 along the peripheral surface of the developing roller 510, and the toner T from between the peripheral surface and the housing 540. Demonstrates the function to prevent leakage.

  The holder 526 is a metal member for assembling various members such as the developing roller 510, and as shown in FIG. 8, the upper seal support portion along the longitudinal direction (that is, the axial direction of the developing roller 510). 526a, a developing roller support portion 526b provided outside the upper seal support portion 526a in the longitudinal direction (the axial direction), intersecting the longitudinal direction (the axial direction), and intersecting the developing roller support portion, A regulating blade support portion 526c facing the longitudinal end of the upper seal support portion 526a.

  The upper seal 520 is supported by the upper seal support portion 526a at the short-side end portion 520a (FIG. 4), and the developing roller 510 is supported at the end by the developing roller support portion 526b. ing. The regulating blade 560 is supported by the regulating blade support portion 526c at both longitudinal ends 564c thereof. The restriction blade 560 is fixed to the holder 526 by being screwed to the restriction blade support portion 526c.

  Thus, the holder 526 assembled with the upper seal 520, the developing roller 510, and the regulating blade 560 is a housing seal 546 (for preventing the toner T from leaking between the holder 526 and the housing 540). It is attached to the housing 540 described above via FIG.

  In the yellow developing device 54 configured as described above, the toner supply roller 550 supplies the toner T stored 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 the toner T passes through the contact position, the layer thickness is regulated and a negative charge is applied. Is imparted (negatively charged). The toner T on the developing roller 510 to which the layer thickness is regulated and to which a negative charge is applied is conveyed to a facing position (developing position) facing the photoconductor 20 by further rotation of the developing roller 510, and is moved to the facing position. Then, the latent image formed on the photoconductor 20 is developed.

  Here, the development of the latent image will be described. As described above, in the printer 10 according to the present embodiment, the jumping development method is used. When the jumping development is executed, a rectangular alternating voltage is applied to the developing roller 510 by the voltage application unit 132. As shown in FIG. 9, the alternating voltage includes a first voltage V1 and a second voltage V2.

  The first voltage V1 is a voltage for directing toner from the developing roller 510 to the photoconductor 20, and its value is -900V. In the present embodiment, as shown in FIG. 9, during development, the potential of the photoconductor 20 is −500 V in the non-image portion (portion corresponding to the white image), and the image portion (portion corresponding to the black image). ) And is -50V, and the toner is negatively charged. When the first voltage V <b> 1 is applied to the developing roller 510, an electric field is formed between the developing roller 510 and the photosensitive member 20 to direct the toner from the developing roller 510 to the photosensitive member 20. Moves toward the photoconductor 20.

  On the other hand, the second voltage V2 is a voltage for directing the toner from the photoconductor 20 to the developing roller 510, and its value is 500V. When the second voltage V <b> 2 is applied to the developing roller 510, an electric field is formed between the developing roller 510 and the photoconductor 20 to direct toner from the photoconductor 20 to the developing roller 510. The toner moves (retracts) to the developing roller 510.

  In the present embodiment, both the time during which the voltage application unit 132 continues to apply the first voltage V1 and the time during which the second voltage V2 continues are, for example, 0.15 ms (milliseconds). Seconds) (ie, the duty ratio is 50%). Accordingly, the period T of the alternating voltage is, for example, 0.3 ms (milliseconds) (see FIG. 9). The average voltage applied to the developing roller 510 by the voltage application unit 132 is larger than the non-image portion potential (−500 V) and smaller than the image portion potential (−50 V), and the value is −200 V. (= (− 900 + 500) / 2).

Next, a method for manufacturing the developing roller 510 will be described.
In order to manufacture the developing roller 510, first, as shown in FIG. 11, a rectangular or strip-shaped large metal plate 165 is prepared. As the large metal plate 165, for example, a galvanized steel plate having a thickness of about 1 mm is used. Subsequently, by pressing the large metal plate 165, as shown in FIG. 11, an elongated rectangular metal plate (second metal plate) 160 having a size corresponding to the developing roller 510, that is, the developing roller 510 is formed. A metal plate 160 serving as a base material is formed.

  Next, as shown in FIG. 12, a pattern PTN is formed on the first plate surface 160 a of the metal plate 160. The formation of the pattern PTN can be performed by well-known sheet metal processing such as press processing.

  Next, the metal plate 160 is pressed into a cylindrical shape (pipe shape) as shown in the press working steps of FIGS. 13A to 13C and FIGS. Side) end surfaces 161a and 161b are brought close to each other.

  That is, first, the metal plate 160 is pressed with the male mold 101 and the female mold 102 shown in FIG. 13A, and both side portions 162a and 162b of the metal plate 160 are formed in an arc shape (preferably approximately 1/4 arc). Bend. In FIG. 13A, in order to make each member easy to understand, the metal plate 160, the male mold 101, and the female mold 102 are shown with an interval between them. In reality, it does not exist, and the metal plate 160 and the male mold 101 and the female mold 102 are in close contact with each other at their contact portions. The same applies to FIGS. 13B and 13C and FIGS. 14A to 14C described later.

  Subsequently, the central portion in the width direction (bending direction) of the metal plate 160 obtained in FIG. 13A is pressed with the male mold 103 and the female mold 104 shown in FIG. It is preferably bent to approximately 1/4 arc).

  Next, as shown in FIG. 13C, the core mold 105 is arranged inside the metal plate 160 obtained in FIG. 13B, and the upper mold 106 and the lower mold 107 shown in FIG. 14A to 14C, the end faces 161a and 161b of the both side parts 162a and 162b of the metal plate 160 are brought close to each other.

  The outer diameter of the core mold 105 shown in FIGS. 13C and 14A to 14C is equal to the inner diameter of the cylindrical hollow pipe to be formed. The radius of the press surface 106c of the upper die 106 and the radius of the press surface 107a of the lower die 107 are equal to the radius of the outer diameter of the hollow pipe to be formed. Further, as shown in FIGS. 14A to 14C, the upper mold 106 is a pair of left and right split molds, and these split molds 106a and 106b are configured to be able to move up and down independently.

  From the state shown in FIG. 13 (c), the upper die 106a on the right side is lowered relative to the lower die 107 as shown in FIG. 14 (a). ), One side of the metal plate 160 is pressed and pressed into a substantially semicircular shape. The lower mold 107 may also be a pair of left and right split molds as in the upper mold 106 (see the split surface 107b), and the lower mold on the same side may be raised during the process shown in FIG.

  As shown in FIG. 14B, the core die 106 is slightly lowered (to such an extent that the end surface 161a on one side and the end surface 161b on the other side can be brought close to each other) and the upper die 106b on the other side. The other side of the metal plate 160 is pressed and bent into a substantially semicircular shape.

  Thereafter, as shown in FIG. 14C, both the core mold 105 and the pair of upper molds 106a and 106b are lowered to form a cylindrical hollow pipe (developing roller 510). In this state, the left and right end surfaces 161a and 161b are sufficiently close to each other through a slight gap. That is, in this cylindrical hollow pipe, both end surfaces 161a and 161b of the metal plate 160 as a base material are close to each other, so that a joint is formed between these both end surfaces 161a and 161b. The joint has a gap due to the separation of the end faces 161a and 161b.

  Next, in this embodiment, in order to increase the roundness of the formed hollow pipe (developing roller 510) and reduce the runout, conventionally known centerless polishing is performed, and the outer peripheral surface of the hollow pipe (developing roller 510) To polish.

  As a result, the roundness of the hollow pipe becomes better than that before the centerless polishing process, and the developing roller 510 has a small deflection amount. Further, in the developing roller 510, the gap between the both end surfaces 161a and 161b is narrowed as shown in FIG. 14A due to the narrower gap between the both end surfaces 161a and 161b. 180 is formed.

  When the developing roller 510 is formed in this manner, the surface of the developing roller 510 is painted. As a coating method, a dry method and a wet method (or a method using both of them) can be adopted, but in this embodiment, a dry method is suitably adopted. Specifically, resin particles are prepared. As the resin particles, fine particles having a diameter of about 10 μm made of an epoxy resin or a polyester resin are preferably used.

  When the resin particles are prepared, first, the resin particles are applied to the developing roller 510. That is, the developing roller 510 is disposed in a painting booth 190 as shown in FIG. The painting booth 190 is provided with a pair of rotation driving members 191 at the lower portion thereof, and these rotation driving members 191 are provided with chucks 192 for supporting the developing roller 510 substantially horizontally. Then, both end portions of the developing roller 510 are held and fixed on the chuck 192, and the chuck 192 is rotated by the rotation driving member 191. As a result, the developing roller 510 is slowly rotated around its axis at a low speed of, for example, about 100 rpm to 500 rpm. Of course, the developing roller 510 may be supported slightly obliquely.

  A tribo gun 193 is disposed on the painting booth 190, and the tribo gun 193 moves on the shaft 194 in the left-right direction in FIG. In addition, an exhaust mechanism 294 is provided at the bottom of the painting booth 190 so that a slow airflow is formed in the painting booth 190 downward. The suction air volume of the exhaust mechanism 294 is set appropriately.

  The developing roller 510 is set to, for example, a negative (-) potential in a single state. The spray particles (resin particles) are charged to a + (plus) high potential while spraying (spraying) the resin particles 195 toward the developing roller 510 using the tribo gun 193. Then, the charged resin particles are adsorbed on the outer peripheral surface of the developing roller 510 to form a resin film 151 (see FIG. 17).

  The resin film is formed by spraying the resin particles in a region corresponding to the pattern PTN formation region. Therefore, without performing the entire length of the developing roller 510, for example, by masking both ends thereof with tape or the like, it is performed only on the central portion excluding both ends, and only on the central portion of the developing roller 510 is selected. Thus, the resin film 151 is formed.

  At the time of this spray coating, the developing roller 510 is rotated around its axis to form a resin film with a substantially uniform thickness over the entire circumference. About the film thickness of this resin film, it forms in about 10 micrometers-30 micrometers, for example. About such a film thickness, it can adjust suitably with the ejection amount, ejection time, etc. of the said resin particle.

  Engaging portions for connecting to various connecting parts such as a conveyance drive gear and an inner gear can be formed on one or both ends of the developing roller 510 at both ends 510b. For example, as shown in FIGS. 17A and 17B, on the opposite positions of the developing roller 510 formed of a cylindrical pipe (hollow pipe), that is, on two formation surfaces that define the diameter of the developing roller 510. The through holes 71a and 71a can be formed, respectively, and an engagement hole (engagement portion) 71 including the pair of through holes 71a and 71a can be formed. According to the engagement hole 71, the connecting component 72 such as a gear can be fixed by a shaft, a pin or the like (not shown).

  As shown in FIGS. 18A and 18B, a D-cut engagement portion 73 can be formed at the end of the developing roller 510. This engaging portion 73 is formed at the end of a cylindrical hollow pipe (developing roller 510), and as shown in FIG. 73a is formed, and as a result, the outer shape of the side surface of the end portion is formed in an apparent D shape as shown in FIG. 18 (b).

  Therefore, a connecting part (not shown) such as a gear is engaged with the engaging portion 73 formed in an apparent D shape so that the connecting part is attached to the developing roller 510 without being idle. Can do. Further, since the engaging portion 73 is formed with a groove-like opening 73a that communicates with the internal hole of the hollow pipe (developing roller 510), the connecting parts can be connected to the developing roller by using the opening 73a. It can be attached to 510 without making it idle. Specifically, by forming a convex portion on the connecting component and fitting the convex portion into the opening 73a, it is possible to prevent idle rotation.

  Further, as shown in FIGS. 19A and 19B, an engaging portion 74 having a groove 74a and a D-cut portion 74b can be formed at the end of the developing roller 510. In the engaging portion 74, the D cut portion 74b is formed at the outer end of the developing roller 510, and the groove 74a is formed inside the D cut portion 74b. As shown in FIG. 19A, the groove 74a is formed by cutting the developing roller 510 approximately half in the circumferential direction. The D-cut portion 74b has an opening 74c extending in a direction orthogonal to the groove 74a outside the groove 74a, and has a pair of bent pieces 74d and 74d on both sides of the opening 74c. That is, as shown in FIG. 19B, when the pair of bent pieces 74d and 74d are bent toward the central axis of the developing roller 510, the portions corresponding to the bent pieces 74d and 74d are The developing roller 510 is recessed from the circular outer peripheral surface.

  Accordingly, by engaging a connecting part (not shown) such as a gear with the groove 74a or with the D-cut portion 74b, the connecting part is idled with respect to the developing roller 510 (conveying roller 15). Can be installed. In addition, the engaging portion 74 can be attached to the developing roller 510 without idling by utilizing the opening 74c formed between the bent pieces 74d. Specifically, by forming a convex portion on the connecting component and fitting the convex portion into the opening 74c, it is possible to prevent idling.

  Further, as shown in FIGS. 20A and 20B, an engaging portion 75 having a groove 75 a and an opening 75 b can be formed at the end of the developing roller 510. In the engaging portion 75, the opening 75b is formed at the outer end of the developing roller 510, and the groove 75a is formed inside the opening 75b. As shown in FIG. 20A, the groove 75a is formed by cutting the developing roller 510 approximately half in the circumferential direction. In the opening 75b, a part of the developing roller 510 is cut out in a rectangular shape in plan view outside the groove 75a, whereby the outer shape of the end side surface is apparently formed in a D shape as shown in FIG. Is.

  Therefore, a connecting part (not shown) such as a gear is engaged with the groove 75a or an apparently D-shaped part formed by the opening 75b, thereby connecting the connecting part to the developing roller. 510 can be attached without idling. Also, in this engaging portion 75, similarly to the engaging portion 73 shown in FIGS. 18 (a) and 18 (b), the connecting part is attached to the developing roller 510 without making it idle by using the opening 75b. be able to.

  In order to form such engagement holes 71 and engagement portions 73, 74, and 75, the developing roller 510 obtained by pressing the metal plate 160 is further subjected to cutting or the like. Can do. For example, with respect to the engaging portion 73 shown in FIGS. 18A and 18B, an apparently D-shaped engaging portion 73 is formed by cutting the end portion to form the opening 73a. Can do. 17A and 17B, the pair of through holes 71a and 71a can be made to oppose each other better by drilling the developing roller 510. .

  However, when the developing roller 510 is further processed in this way, the cost and time efficiency are reduced by adding a separate processing step only for the formation of the engaging portion. Therefore, before the developing roller 510 is pressed, a development engaging portion that becomes an engaging portion is formed on the metal plate by pressing, and the metal plate is pressed to form the developing roller 510. It is preferable to form the joint at the same time.

  Specifically, when the large metal plate (first metal plate) 165 shown in FIG. 11A is pressed into an elongated rectangular plate-shaped metal plate (second metal plate) 160, the large metal plate 165 is used. At the same time as the processing from the metal plate 160 to the small metal plate 160, a developed engagement portion such as a notch shape, a projecting piece shape, a hole shape, or a groove shape is formed at the end portion of the obtained metal plate 160. For example, as shown in FIG. 21 (a), a pair of through holes 71a and 71a are processed at predetermined positions on the end of the metal plate 160, and these are used as the deployment engaging portions 76a, thereby pressing the metal plate 160. By processing, the pair of through holes 71a and 71a can be opposed to each other, and the engagement holes 71 shown in FIGS. 17A and 17B can be formed.

  As shown in FIG. 21 (b), the end of the metal plate 160 is cut out into a predetermined shape to form a deployment engagement portion 76b, and the metal plate 160 is pressed so as to be processed in FIGS. The engaging portion 74 shown in b) can be formed. That is, the engagement portion 74 can be formed by forming a pair of notches (recesses) 74e, 74e and a pair of protrusions 74f, 74f as the deployment engagement portion 76b. However, in this example, after the metal plate 160 is pressed, the pair of protruding pieces 74f and 74f need to be folded and pressed into the bent piece 74d. It is somewhat insufficient to increase the conversion.

  Therefore, as shown in FIG. 21 (c), the end of the metal plate 160 is cut out into a predetermined shape to form a deployment engagement portion 76c, and the metal plate 160 is pressed to form FIG. 20 (a). , (B) can be formed. That is, the engaging portion 75 can be formed by forming a pair of notches (recessed portions) 75c and 75c and a pair of projecting pieces 75d and 75d as the deployment engaging portion 76c. In this example, when the metal plate 160 is pressed, the pair of projecting pieces 75d and 75d are also bent into an arc shape to form the opening 75b shown in FIG. 20B between the projecting pieces 75d and 75d. Can do. Therefore, it is not necessary to add further processing to the developing roller 510 formed by press processing, and this can sufficiently increase the cost and time efficiency of the processing steps.

  Further, as shown in FIG. 6 and the like, in the developing roller 510 according to this embodiment, the joint 180 is formed so as to be parallel to the central axis of the developing roller 510 formed of a cylindrical hollow pipe. The invention is not limited to this. For example, a joint formed between a pair of ends of a metal plate 160 serving as a base material is formed on the outer peripheral surface of the cylindrical pipe (roller body). On a straight line parallel to the central axis, the line may be overlapped only at one or a plurality of points without overlapping with the line segment.

  Specifically, as shown in FIG. 22A, the outer peripheral surface of the developing roller 510 is formed in the circumferential direction so as to intersect with the joint 81 without being parallel to the central axis 510c of the developing roller 510. You may form so that it may extend from one end of the developing roller 510 to the other end while extending. In order to form the joint 181 in this way, an elongated parallelogram-shaped metal plate 160a as shown in FIG. 22B is used as the base metal plate, instead of the elongated rectangular metal plate 160. Press processing is performed so that the straight line indicated by reference numeral 510c is the central axis. As a result, the developing roller 510 shown in FIG. 22A is obtained, and the joint 181 is not parallel to the central axis 510c.

  In the developing roller 510 shown in FIG. 22A, the joint 181 is formed so as to rotate less than one round on the peripheral surface from one end of the developing roller 510 to the other end. This is to facilitate the press working of the metal plate 160a. However, as shown in FIG. 22C, the joint 182 may be formed so as to turn one or more times around the peripheral surface from one end of the developing roller 510 to the other end, that is, spirally. In that case, the angle θ in the elongated parallelogram-shaped metal plate 160a shown in FIG. 22B may be set to a more acute angle as the metal plate serving as the base material.

  As shown in FIG. 23A, the joint 183 may be formed in a wavy line formed of a curve such as a sine wave. In order to form the joint 183 in this way, as a metal plate serving as a base material, as shown in FIG. 23 (b), a metal plate having an elongated and substantially rectangular shape and both long sides thereof being formed in a wavy shape Using 160b, press working is performed so that the straight line indicated by reference numeral 510c is the central axis. In addition, since a pair of long sides formed in a wavy line are brought close to each other by pressing, naturally, when one long side becomes a peak portion between corresponding points, a valley is formed on the other long side. Conversely, when one long side is a valley, the other long side is a mountain. In this example, the center line of the joint 183 is formed so as to be parallel to the center axis of the developing roller 510. However, the center line of the joint 183 is also not parallel to the center axis of the developing roller 510. You may form in. In that case, as a metal plate to be a base material, a long and parallelogram-shaped metal plate as shown in FIG. 22B, and both of which long sides are formed in a wavy shape may be used. .

  As shown in FIG. 24A, the joint 184 may be formed in a wavy shape bent in a hook shape. In order to form the joint 184 in this way, as a metal plate as a base material, as shown in FIG. 24 (b), it is an elongated, substantially rectangular shape, and both of its long sides are bent into a wavy shape like a hook. Using the formed metal plate 160c, press working is performed so that the straight line indicated by reference numeral 510c is the central axis. Also in this metal plate 160c, between the portions corresponding to each other in a pair of long sides formed in a wavy line, when one long side becomes a peak, the other long side becomes a valley, and conversely, When the long side is a trough, the other long side is a crest. In this example as well, the center line of the joint 184 is formed to be parallel to the center axis of the developing roller 510. However, as in the case of the joint 183, the center line is not parallel to the center axis of the developing roller 510. You may form as follows.

  About a joint, it is not limited to the example shown in FIGS. 22-24, A various shape is employable. For example, the wavy line composed of the curve shown in FIG. 23 (a) may be combined with the bent wavy line shown in FIG. 24 (a), and these may be combined with an oblique line as shown in FIG. Also good.

  As for the joint of the developing roller 510 formed of a cylindrical hollow pipe, in addition to the configuration exemplified above, for example, as shown in FIG. 25A, a linear portion 185a parallel to the central axis of the developing roller 510 and this It may be formed having a rectangular wave-shaped bent portion 185 composed of a straight portion 185b orthogonal to the rectangular portion. Even in the joint having such a bent portion 185, if a groove is temporarily formed due to the joint, the groove is simultaneously applied to the entire width of the paper P during paper feeding. Since there is no contact, the conveyance speed of the paper P becomes substantially constant, and uneven development is prevented.

  The bent portion 185 may be formed over the entire length of the developing roller 510 as shown in FIG. 25B, and as shown in FIG. 25C, both ends except for the central portion thereof. It may be selectively formed in the part. When the bent portions 185 are formed only at both ends as shown in FIG. 25C, a central straight portion 186 parallel to the central axis of the developing roller 510 is formed between the bent portions 185. However, although not shown, the central straight portion between the bent portions 185 may be formed as an oblique line that is not parallel to the central axis 510c as shown in FIG.

  When the bent portion 185 is formed at the joint, and thus the bent portion 185 is formed as a fitting portion by unevenness, the bent portion 185 (fitting portion) is fitted as designed, and the tip of the convex portion and this It becomes difficult to make it approach (match) without a gap between the recesses corresponding to. Therefore, when the bent portion 185 is formed over the entire length of the developing roller 510, the developing roller 510 is likely to be distorted or twisted. Therefore, if the bent portions 185 are formed only at both ends as shown in FIG. 25C, it is possible to suppress the occurrence of such distortion and twist.

  As shown in FIG. 25B, when the bent portion 185 is formed over the entire length of the developing roller 510, the joint 187 including the bent portion 185 is formed as shown in FIG. A plurality of intersecting portions 187a composed of the straight portions 185b, a first straight portion 187b connecting between the end portions on one side of the intersecting portion 187a, and a second straight portion 187c connecting between the end portions on the other side. You may form so that it may consist of. Here, the first straight portion 187b and the second straight portion 187c are formed so as to be substantially parallel to the central axis of the developing roller 510, and the intersecting portion 187a is orthogonal to the first straight portion 187b and the second straight portion 187c. That is, it is formed so as to be orthogonal to the central axis of the developing roller 510. Further, the second straight portion 187c is formed shorter than the first straight portion 187b.

  In the case of forming the joint 187 having such a configuration, in particular, the distance d3 between the pair of end portions facing each other in the second linear portion 187c is defined as the distance between the pair of end portions facing each other in the first linear portion 187b. It is preferable to form it longer than the distance d4. Note that the distances d3 and d4 between the pair of end portions referred to here are both the distances between the end portions in the gap formed on the outer peripheral surface of the developing roller 510.

  In this way, the accuracy of the shape and dimensions of the developing roller 510 as a cylindrical hollow pipe can be further increased, and therefore uneven development due to deformation of the developing roller 510 and the like can be prevented. In other words, in the metal plate serving as a base material for forming the developing roller 510, one end portion constituting the second straight portion 187c is a pair of adjacent intersecting portions 187a and 187a and these end portions. It becomes the convex piece 187d which makes the 2nd linear part 187c which connects between an external shape. Therefore, when pressing the metal plate to bring the convex piece 187d close to the opposite end, as shown by a two-dot chain line in FIG. The sheet is not sufficiently bent into a planar shape, and is in a state of floating by a dimension t1 with respect to the opposite end, and as a result, a step is formed in the second linear portion 187c. Then, due to this level difference, the resulting developing roller 510 is likely to be deformed, and it is difficult to obtain good accuracy in terms of shape and dimensions.

  Therefore, by making the distance d3 between the ends of the second straight line portion 187c longer than the distance d4 between the ends of the first straight line portion 187b formed longer than the second straight line portion 187c, FIG. As shown by the solid line in (b), the dimension t2 of the floating portion of the tip of the convex piece 187d is smaller (smaller) than the t1, and a step is formed in the second linear portion 187c. Can be suppressed. In FIG. 26B, the dimension t2 is also shown large for easy understanding, but actually the dimension t2 is almost close to zero and there is no substantial step. That is, by suppressing the formation of a step in the second linear portion 187c in this way, deformation of the developing roller 510 due to the step can be suppressed, and the accuracy of the shape and dimensions can be increased.

  As shown in FIG. 25 (c), when the bent portions 185 are formed only at both ends of the developing roller 510, as shown in FIG. 27, the cross portions 187a (straight portions 185b) of the bent portions 185 are mutually connected. It is preferable that the distance d5 between the pair of opposed end portions be shorter than the distance d6 between the pair of opposed end portions in the central straight portion 186.

  In this way, the distance d5 becomes relatively short and the gap between the end portions at the intersecting portion 187a becomes very narrow. Therefore, when the metal plate serving as the base material for forming the developing roller 510 is pressed The shift in the length direction (axial direction) between the one end and the other end is regulated by the pair of opposing ends constituting the intersecting portion 187a. Therefore, distortion or twist is hardly generated in the obtained developing roller 510, and development unevenness due to such distortion or twist is prevented.

  As shown in FIG. 25C, when the bent portion 185 is formed only at both ends of the developing roller 510, the convex piece 187d of the bent portion 185 is formed as shown in FIG. The distance d7 between the pair of end portions facing each other in the two straight line portions 187c may be formed shorter or longer than the distance d6 between the pair of end portions facing each other in the central straight line portion 186. Good.

  If the distance d7 is formed shorter than the distance d6, the gap formed between a pair of opposing ends can be more easily uniformed when the entire length of the joint is viewed. The shape and dimensions of the developing roller 510 obtained thereby The accuracy of will be higher. That is, the length of the central straight portion 186 is longer than the length of the second straight portion 187c in the bent portion 185, and therefore, the distance between the pair of end portions in the central straight portion 186 is higher than that of the second straight portion 187c. Can be close. Therefore, the distance between the pair of end portions of the central straight portion 186 that can make the accuracy between the end portions relatively better is longer than that of the second straight portion 187c to increase the gap. However, this gap can be made sufficiently uniform, so that uneven development due to distortion or twisting of the developing roller 510 obtained can be prevented.

  On the other hand, if the distance d7 is formed longer than the distance d6, as shown in FIG. 26 (b), the dimension t2 that the tip side of the convex piece 187d floats is reduced (smaller), thereby causing a step in the second straight portion 187c. Is suppressed from forming. Therefore, the formation of a step in the second linear portion 187c is suppressed in this way, so that the deformation of the developing roller 510 due to the step is suppressed, and the development of unevenness is improved by increasing the accuracy of the shape and dimensions. Is prevented.

  Regarding the joint of the developing roller 510 formed of a cylindrical hollow pipe, in addition to the above example, for example, as shown in FIG. 28A, an intersection 188 a in the bent portion 188 is formed with respect to the central axis of the developing roller 510. The angle α on the tip side of the convex piece 188b in the bent portion 188 may be formed to be an obtuse angle (less than 180 °). In this way, when the pair of end surfaces are brought close to each other in the press working of the metal plate, the tip of the convex piece 188b can be easily fitted into the corresponding concave portion, and thus the developing roller 510 is distorted or twisted. Can be suppressed.

  In the structure in which the bent portion 185 is formed only at both ends as shown in FIG. 25 (c), the bent portion 185 is formed from the curve shown in FIG. 23 (a) as shown in FIG. 28 (b), for example. The wavy line 89a may be replaced with the bent wavy line 189b shown in FIG. 24 (a) as shown in FIG. 28 (c).

  The rectangular wave-like bent portion 185 shown in FIG. 25 (a) and the wavy line 189a made of a curve shown in FIG. 28 (b) may be combined to form a joint. And a bent wavy line 189b shown in FIG. 28C may be combined to form a joint.

  When an image is formed by the laser beam printer 10 configured as described above, the photosensitive member 20 and the developing roller 510 are rotated in the reverse direction, and a rectangular alternating voltage (first voltage in FIG. V1 and second voltage V2) are applied between the photoreceptor 20 and the developing roller 510.

  Since the first voltage V1 and the second voltage V2 are alternately applied by the voltage application unit 132, when developing the latent image, the toner moves from the developing roller 510 to the photoconductor 20, and the photoconductor. The movement (return) from 20 to the developing roller 510 is repeated alternately. The toner T on the developing roller 510 that has passed the developing position by the rotation of the developing roller 510 passes through the upper seal 520 and is collected in the developing device without being scraped off by the upper seal 520. Further, the toner T still remaining on the developing roller 510 is peeled off by the toner supply roller 550.

  In the present embodiment, the interval (distance between the end surfaces 161a and 161b) d1 of the gap 180 formed in the developing roller 510 is about 0.01 mm to 0.09 mm, and the developing roller 510 is rotated when the developing roller 510 rotates. The moving speed V of the surface is 300 mm / s (0.3 mm / ms). For this reason, the time required for the gap 180 to pass through one point on the rotating surface of the photoconductor 20 by rotation is 0.03 ms to 0.3 ms. On the other hand, the period T of the alternating voltage is, for example, 0.3 ms (milliseconds). For this reason, the gap 180 passes through one point on the rotating surface of the photoconductor 20 in a period shorter than the period in which the alternating voltage for one cycle is applied.

  Since no alternating voltage is applied to the gap 180, the electric field is not applied to the toner while the gap 180 passes one point on the rotating surface of the photoconductor 20. When the period becomes longer than the period T of the alternating voltage, the alternating current voltage is applied between the developing roller 510 and the photosensitive member 20 (that is, the image formation is controlled). No movement occurs, and no image is formed during that period. For this reason, image irregularities such as white streaks appear in the image.

  On the other hand, in this embodiment, the time during which the gap 180 passes through one point on the rotating surface of the photoconductor 20 is longer than the period T of the alternating voltage, and the alternating voltage for one period is applied. Since the gap 180 passes through one point on the rotating surface of the photoconductor 20 in a period shorter than the period during which it is applied, at least a part of the alternating voltage for one cycle is always applied to the toner. For this reason, the occurrence of image unevenness is suppressed.

  As described above, according to the present embodiment, when the developing roller 510 is formed, the uneven pattern PTN constituting the first groove portion 512a and the second groove portion 512b is formed on the first plate surface 160a of the metal plate 160 by pressing. The metal plate 160 is formed so that the first plate surface 160a on which the concavo-convex pattern PTN is formed becomes an outer surface, and the pair of opposite sides 161a and 161b of the metal plate 160 are close to each other. And a step of forming into a cylindrical shape by press working.

  Since the hollow cylindrical developing roller 510 can be formed by pressing the metal plate 160, the developing roller 510 that is lighter in weight than the solid cylindrical roller can be manufactured. In addition, since the metal plate 160 is pressed after the predetermined uneven pattern PTN is formed on the first plate surface 160a of the metal plate 160, the degree of freedom of the uneven pattern PTN that can be formed on the metal plate 160. Will spread. In addition, since the pair of end surfaces 161a and 161b of the metal plate 160 are close to each other without being in close contact with each other, a place for escape of compressed air can be ensured. Thereby, vibration during rotation of the developing roller 510 can be prevented.

The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, when the developing roller 510 is formed, the pair of end surfaces 161a and 161b of the metal plate 160 are separated from each other. However, the present invention is not limited to this. For example, the end surface 161a And a part between 161b may be fixed by a welding process. In this case, it is preferable to perform the welding process before the coating process is performed on the metal plate 160.

  In the above-described embodiment, an example in which a grid-like groove portion is formed as the uneven pattern PTN formed on the first plate surface 160a of the metal plate 160 has been described. However, the present invention is not limited to this example. It is possible to appropriately form various shapes such as a groove portion, a square in plan view, a polygonal pattern including a triangle, a circular pattern, a combination of these, and the like. In the present invention, since a pattern can be formed on the metal plate 160 instead of forming a pattern on a cylindrical or columnar side surface, a wide variety of patterns can be formed. In addition, it is not restricted to press work, You may form these uneven | corrugated pattern PTN by another working method.

  DESCRIPTION OF SYMBOLS 10 ... Laser beam printer (image forming apparatus) 160 ... Metal plate 160a ... 1st board surface PTN ... Uneven pattern 510 ... Developing roller

Claims (6)

A pattern forming step of forming a predetermined uneven pattern on the first plate surface of the metal plate by pressing;
The metal plate is formed into a cylindrical shape by pressing so that the first plate surface on which the concave / convex pattern is formed becomes an outer surface and a pair of edges of the metal plate face each other at a predetermined interval. A developing roller manufacturing method comprising: a cylindrical machining step. The method for manufacturing a developing roller according to claim 1, wherein the uneven pattern includes at least one of a linear pattern, a curved pattern, a polygonal pattern, and a circular pattern. The developing roller manufacturing method according to claim 1, further comprising a welding step of connecting at least a part of the pair of end sides by welding. The developing roller according to any one of claims 1 to 3, further comprising a coating step of coating a resin film on the first plate surface of the metal plate formed in a cylindrical shape. Production method. 5. The development according to claim 1, wherein the pattern forming step presses a second plate surface of the metal plate opposite to the first plate surface. 6. Roller manufacturing method. The metal plate formed in a cylindrical shape is
6. The image forming apparatus comprising: an image carrier that carries a latent image; and a developing roller that is disposed to face the image carrier, and is used as the developing roller. The manufacturing method of the developing roller as described in any one of these.

Images