JP2006047929A - Image forming apparatus, image forming system and method for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent irregular density of an image and increase in fog or scattering of a developer. <P>SOLUTION: This image forming apparatus is equipped with: an image carrying body to carry a latent image; a developer carrying body carrying a developer to convey the developer to a position opposing the image carrying body to develop a latent image carried by the image carrying body with the developer conveyed to the position; a transferring unit to transfer the developer image formed on the image carrying body by developing the latent image to a medium to form an image; a voltage applying unit to alternately apply on the developer carrying body, a first voltage to allow the developer to proceed from the developer carrying body to the image carrying body and a second voltage to allow the developer to proceed from the image carrying body to the developer carrying body so as to develop the latent image; a first voltage setting unit to set the first voltage based on the conveyed amount information relating to the conveyed amount of the developer by the developer carrying body; and an image density control unit to keep the first voltage set by the first voltage setting unit and to vary the second voltage to control the density of an image to be formed on the medium. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, an image forming system, and an image forming method.

As an image forming apparatus, for example, an image carrier for carrying a latent image, a developer is carried, the developer is conveyed to a position facing the image carrier, and the developer conveyed to the position is used. A developer carrier for developing the latent image carried on the image carrier, and a transfer for transferring the developer image formed on the image carrier by developing the latent image to a medium to form an image There is a printer having a unit. The printer also includes a first voltage for directing the developer from the developer carrier to the image carrier and development from the image carrier to the developer carrier for developing the latent image. A voltage applying unit that alternately applies a second voltage for directing the developer to the developer carrying member; Note that developers having different charge amounts are carried on the developer carrier by mirror image force or the like.
JP 2002-182457 A

Further, the printer has an image density adjusting unit for adjusting the density of the image formed on the medium. In consideration of preventing a part of the developer carried on the developer carrier from moving toward the image carrier (so-called “selective development”), the first voltage (Vmax) and the second voltage (Vmin) It is effective to adjust the image density by changing only the second voltage.
However, when the density of the image is adjusted by changing only the second voltage, the value that the second voltage can take becomes wide, and there is a possibility that the image may be uneven depending on the value of the second voltage. Further, when the absolute value of the first voltage is too large, there is a possibility that fogging and developer scattering may increase.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent unevenness in image density and increase in fog and scattering of developer.

  The main aspect of the present invention is an image carrier for carrying a latent image, a developer carrying the developer to a position facing the image carrier, and the image conveyed by the developer carried to the position. A developer carrier for developing the latent image carried on the carrier, and a transfer unit for transferring the developer image formed on the image carrier by developing the latent image to a medium to form an image; For developing the latent image, a first voltage for directing the developer from the developer carrier to the image carrier, and for directing the developer from the image carrier to the developer carrier. And a second voltage for alternately applying the second voltage to the developer carrier, and a first voltage for setting the first voltage based on conveyance amount information relating to the developer conveyance amount by the developer carrier. One voltage setting unit and the first voltage set by the first voltage setting unit Maintaining, and said second voltage is changed, and an image forming apparatus characterized by having an image density adjustment unit for adjusting the density of the image formed on the medium.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  At least the following will be made clear by the description of the present specification and the accompanying drawings.

An image carrier for carrying a latent image, and a developer carrying the developer to a position opposite to the image carrier, and the developer carried to the position being carried on the image carrier. A developer carrying member for developing the latent image, a transfer unit for transferring the developer image formed on the image carrier by developing the latent image to a medium, and forming an image; A first voltage for directing the developer from the developer carrier to the image carrier and a second voltage for directing the developer from the image carrier to the developer carrier for development; , And a first voltage setting unit for setting the first voltage based on transport amount information regarding the transport amount of the developer by the developer carrier. Maintaining the first voltage set by the first voltage setting unit, and By changing the serial second voltage, the image forming apparatus characterized by having an image density adjustment unit for adjusting the density of the image formed on the medium.
According to such an image forming apparatus, since an appropriate first voltage can be set according to the transport amount of the developer carrying member, uneven density of the image is prevented, and an increase in fogging and scattering of the developer is prevented. It becomes possible to do.

The image forming apparatus may further include a layer thickness regulating member that is in contact with the developer carrying member and regulates a layer thickness of the developer carried on the developer carrying member. The carry amount may be the carry amount after the layer thickness is regulated by the layer thickness regulating member.
In the case where the layer thickness regulating member is provided, the layer thickness of the developer carried on the developer carrying body is regulated to be constant, and the latent image is developed by the developer. Therefore, it is most effective to use the developer conveyance amount by the developer carrier after the layer thickness is regulated by the layer thickness regulating member as the developer conveyance amount by the developer carrier. Therefore, when the first voltage setting unit sets the first voltage based on the transport amount information related to the transport amount of the developer by the developer carrier after the layer thickness is regulated by the layer thickness regulating member Therefore, it is possible to effectively prevent unevenness in the density of the image and to prevent an increase in fog and scattering of the developer.

Further, in this image forming apparatus, the layer thickness regulating member has a tip on the side of the layer thickness regulating member that comes into contact with the developer carrying body, on the developer carrying body of the layer thickness regulating member. The conveyance amount information is distance information related to the distance from the tip to the contact position, as viewed from the contact position where the contact is made. It may be there.
When the distance from the leading end to the contact position changes, the amount of developer carried on the developer carrying member changes, so the amount of developer transported by the developer carrying member also changes. Therefore, when the transport amount information is distance information, it is possible to easily and appropriately grasp the developer transport amount by the developer carrier.

In the image forming apparatus, the transport amount information may be surface roughness information related to the surface roughness of the developer carrier.
When the surface roughness of the developer carrier changes, the amount of developer transported by the developer carrier also changes. Therefore, when the developer information is surface roughness information, it is possible to easily and appropriately grasp the amount of developer transported by the developer carrier.

  In addition, the image forming apparatus is detachable from the image forming apparatus main body, includes the developer carrying member, and includes a developing device for containing the developer carried on the developer carrying member, The developing device is provided with a developing device storage unit that stores the transport amount information related to the transport amount of the developer accommodated in the developing device, and the first voltage setting unit is configured to include the developing device storage unit. The first voltage may be set on the basis of the transport amount information read from.

Further, in this image forming apparatus, the transfer unit is provided with a transfer mediating member serving as a mediator when transferring the developer image formed on the image carrier to the medium, and the transfer unit Transfers the developer image formed on the image carrier to the transfer medium member, and transfers the developer image transferred to the transfer medium member to the medium to form an image, and the medium. A density detecting member for detecting the density of the test pattern formed on the transfer medium member to adjust the density of the image formed on the transfer medium member, and the image density adjusting unit The second voltage may be changed based on the concentration detection result.
In such a case, it is possible to easily adjust the image density.

In the image forming apparatus, the developer carrier may be made of metal.
When the developer carrying member is made of metal, the mirror image force acting between the developer and the developer carrying member is strong. In such a case, in order to prevent selective development, the absolute value of the first voltage is set large, and fogging and developer scattering are likely to increase. Therefore, when the developer carrying member is made of metal, an effect that it is possible to prevent an increase in fogging and scattering of the developer is more effectively achieved.

In the image forming apparatus, the developer may be manufactured by a pulverization method.
When the developer is manufactured by a pulverization method, the charge distribution of the developer is wide. In such a case, in order to prevent selective development, the absolute value of the first voltage is set large, and fogging and developer scattering are likely to increase. Therefore, when the developer is manufactured by a pulverization method, the effect that it is possible to prevent an increase in fogging and scattering of the developer is more effectively achieved.

  Further, in this image forming apparatus, before the voltage application unit applies the first voltage and the second voltage to the developer carrier, the developer carried on the developer carrier is removed. When the voltage application unit applies the first voltage to the developer carrier without contacting the image carrier, the developer carried on the developer carrier is applied to the image carrier. When the voltage application unit applies the second voltage to the developer carrier, the developer attached to the image carrier is transferred to the developer carrier. It is also possible to fly back toward the developer carrier.

Further, an image carrier for carrying a latent image, a developer is carried and the developer is conveyed to a position opposite to the image carrier, and the developer conveyed to the position causes the image carrier to A developer carrying member for developing the carried latent image, a transfer unit for transferring the developer image formed on the image carrying member by developing the latent image onto a medium, and forming the image; A first voltage for directing the developer from the developer carrier to the image carrier and a second for directing the developer from the image carrier to the developer carrier for image development. A voltage application unit that alternately applies a voltage to the developer carrier, and a first voltage setting for setting the first voltage based on transport amount information relating to the transport amount of the developer by the developer carrier. And the first voltage set by the first voltage setting unit, An image density adjusting unit for adjusting the density of an image formed on the medium by changing the second voltage; and a developer carried on the developer carrying member in contact with the developer carrying member. A layer thickness regulating member for regulating the layer thickness of the agent,
The transport amount of the developer is the transport amount after the layer thickness is regulated by the layer thickness regulating member,
The layer thickness regulating member is configured such that the tip of the layer thickness regulating member on the side in contact with the developer carrying member is viewed from the contact position of the layer thickness regulating member in contact with the developer carrying member. It is provided so as to face the upstream side in the rotation direction of the developer carrier, and the transport amount information is distance information related to the distance from the tip to the contact position,
The transport amount information is surface roughness information related to the surface roughness of the developer carrier.
An image forming apparatus main body is detachable and includes the developer carrying member, and has a developing device for containing the developer carried on the developer carrying member. The developing device includes the developing device. A developing device storage unit storing the transport amount information related to the transport amount of the stored developer is provided, and the first voltage setting unit is based on the transport amount information read from the developing device storage unit. To set the first voltage,
The transfer unit is provided with a transfer medium member that serves as a medium when transferring the developer image formed on the image carrier to the medium. The transfer unit is formed on the image carrier. The developer image is transferred to the transfer medium member, and the developer image transferred to the transfer medium member is transferred to the medium to form an image, and the density of the image formed on the medium is adjusted. Therefore, the image density adjusting unit has a density detecting member for detecting the density of the test pattern formed on the transfer medium member, and the image density adjusting unit is configured to detect the density of the test pattern by the density detecting member. Change two voltages,
The developer carrier is made of metal,
The developer is manufactured by a pulverization method,
Before the voltage application unit applies the first voltage and the second voltage to the developer carrier, the developer carried on the developer carrier is not in contact with the image carrier, When the voltage application unit applies the first voltage to the developer carrier, the developer carried on the developer carrier flies toward the image carrier and adheres to the image carrier. When the voltage application unit applies the second voltage to the developer carrier, the developer attached to the image carrier flies toward the developer carrier and the developer carrier. An image forming apparatus that returns to step (a).
According to such an image forming apparatus, the effect that it is possible to prevent unevenness in the density of an image and to prevent an increase in fogging and scattering of the developer is most effectively achieved.

Also, a computer and an image forming apparatus connectable to the computer, the image carrier for carrying a latent image, and a developer carrying the developer at a position facing the image carrier. A developer carrying member for developing the latent image carried on the image carrier by the developer carried and conveyed to the position; and a developer image formed on the image carrier by developing the latent image A transfer portion for transferring an image to a medium to form an image, a first voltage for directing the developer from the developer carrier to the image carrier for developing the latent image, and the image carrier A voltage applying unit that alternately applies a second voltage for directing the developer from the body to the developer carrying body to the developer carrying body, and a carry amount related to a carry amount of the developer by the developer carrying body. A first for setting the first voltage based on the information An image density for adjusting the density of an image formed on the medium by maintaining the first voltage set by the pressure setting unit and the first voltage setting unit and changing the second voltage An image forming system comprising: an adjustment unit;
According to such an image forming system, since the image forming apparatus capable of preventing the uneven density of the image and preventing the increase of the fog and the scattering of the developer is provided, it is superior to the conventional one. An image forming system can be realized.

Further, a first for directing the developer from the developer carrier to the image carrier carrying the latent image based on the carry amount information regarding the developer carry amount by the developer carrier carrying the developer. In order to adjust the density of the image formed on the medium, and to set the voltage, the set first voltage is maintained, and the developer is directed from the image carrier to the developer carrier. A step of changing the second voltage for developing, the step of developing the latent image by alternately applying the maintained first voltage and the changed second voltage to the developer carrier, and And transferring the developer image formed on the image carrier to the medium by developing a latent image to form an image.
According to such an image forming method, it is possible to prevent unevenness in the density of the image and to prevent an increase in fog and scattering of the developer.

=== Overall Configuration of Image Forming Apparatus ===
Next, the overall configuration of the printer 10 will be described with reference to FIG. 1, taking a laser beam printer (hereinafter also referred to as a printer) 10 as an example of the image forming apparatus. 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.

<Overall Configuration of 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 developer holding unit along the rotation direction of a photoconductor 20 as an example of an image carrier that carries a latent image. A unit 50, a primary transfer unit 60, an intermediate transfer body 70, and a cleaning unit 75; a secondary transfer unit 80; a fixing unit 90; A control unit 100 for controlling the unit and the like 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. The charging potential on the surface of the photoconductor 20 charged by the charging unit 30 is uniform. In order to charge the photoreceptor 20, a charging bias generator 127 b (see FIG. 7) provided in the charging unit drive control circuit applies a charging bias to the charging unit 30. Further, the charging unit drive control circuit is provided with a charging bias control circuit 127a that plays a role of controlling on / off of the charging bias and setting an appropriate charging bias value.

  The exposure unit 40 is a device that forms a latent image on the photoreceptor 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. Thereby, the portion of the photoconductor 20 irradiated with the laser becomes an image portion, and the portion of the photoconductor 20 not irradiated with the laser becomes a non-image portion. Note that the image portion potential is different from the non-image portion potential (charging potential).

The developing device holding unit 50 converts the latent image formed on the photoconductor 20 into black (K) toner, magenta (M) toner, and cyan developing contained in the black developing device 53. This is an apparatus for developing using cyan (C) toner contained in the device 52 and yellow (Y) toner contained in the yellow developing device 54.
In the present embodiment, the developing device holding unit 50 can be rotated to move the positions of the four developing devices 51, 52, 53, and 54 as an example of a developing device. That is, the developing device holding unit 50 holds the four developing devices 51, 52, 53, and 54 by the four attaching / detaching portions 50a, 50b, 50c, and 50d provided in the printer main body 10a (image forming apparatus main body). The four developing devices 51, 52, 53, 54 are rotatable about the rotation shaft 50e while maintaining their relative positions. Each time the photoconductor 20 makes one rotation, the photoconductor 20 is selectively opposed to the photoconductor 20, and toner T as an example of a developer accommodated in each developing device 51, 52, 53, 54 is used. The latent image formed above is developed. Details of each developing device will be described later.

  The primary transfer unit 60 is a device for transferring a toner image as an example of a developer image formed on the photoconductor 20 to an intermediate transfer body 70 as an example of a transfer medium member. Then, a full color toner image is formed on the intermediate transfer body 70. The intermediate transfer member 70 is an endless belt, and is driven to rotate at substantially the same peripheral speed as the photosensitive member 20.

  An example of a density detection member that detects the density of a patch image (test pattern) formed on the intermediate transfer body 70 in the vicinity of the intermediate transfer body 70 to adjust the density of the image formed on the recording medium. As a patch sensor PS. The patch sensor PS is a reflective optical sensor that functions to detect the density. More specifically, the patch sensor PS has a light emitting unit for emitting light and a light receiving unit for receiving light, and light emitted from the light emitting unit toward the patch image, that is, incident light is generated by the patch image. The reflected light is received by the light receiving unit and converted into an electrical signal. And the magnitude | size of an electrical signal is measured as an output value of the light receiving sensor according to the intensity of the received reflected light. Since there is a certain relationship between the density of the patch image and the intensity of the received reflected light, the density of the patch image is detected by measuring the magnitude of the electrical signal.

  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 recording medium which is an example of a medium. Examples of the recording medium include paper, film, and cloth. Further, “transfer section” in the claims refers to the primary transfer unit 60, the intermediate transfer body 70, and the secondary transfer unit 80. The intermediate transfer member 70 is a medium for transferring the toner image formed on the photosensitive member 20 to a recording medium.

  The fixing unit 90 is a device for fusing a single color toner image or a full color toner image transferred onto a recording medium onto a recording medium such as paper 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. 7, the control unit 100 includes a controller unit 101 and a unit control unit 102. An image signal is input to the controller unit 101, and the unit control unit 102 receives the command based on the image signal. The respective units are controlled to form an image.

=== Overview of Developer ===
Next, a configuration example of the developing device will be described with reference to FIGS. FIG. 2 is a conceptual diagram of the developing device, and FIG. 3 is a cross-sectional view showing main components of the developing device. FIG. 4 is a view showing a configuration around the regulating blade 560. Note that the cross-sectional view shown in FIG. 3 represents a cross-section obtained by cutting the developing device along a plane perpendicular to the longitudinal direction shown in FIG. In FIG. 3, as in FIG. 1, the up and down directions are indicated by arrows, and the yellow developing device 54 is in a developing position facing the photoconductor 20.

The developing device holding unit 50 can be equipped with a black developing device 51, a magenta developing device 53, a cyan developing device 52, and a yellow developing device 54. The construction of each developing device is the same. The yellow developing device 54 will be described.
The yellow developing device 54 includes a developing roller 510 as an example of a developer carrier, a seal member 520, a toner container 530, a housing 540, a toner supply roller 550, a regulating blade 560 as an example of a layer thickness regulating member, and the like. ing.

  The developing roller 510 carries the toner T and transports it to a position (development position) facing the photoconductor 20, and develops the latent image carried on the photoconductor 20 by the toner T transported to the development position. The developing roller 510 is made of metal, and is made of, for example, aluminum, stainless steel, iron, or the like. If necessary, nickel plating, chrome plating, or the like, and sand blasting or the like is applied to the toner carrying area. . The surface of the developing roller 510 has a predetermined surface roughness Rz (Rz indicates a ten-point average roughness), and the developing roller 510 carries and transports toner T mainly between the convex portions. If the surface roughness Rz is large, the amount of toner T conveyed by the developing roller 510 is large.

  Further, as shown in FIG. 2, the developing roller 510 is supported at both ends in the longitudinal direction, and is rotatable about the central axis. As shown in FIG. 3, the developing roller 510 rotates in a direction (counterclockwise in FIG. 3) opposite to the rotation direction of the photoconductor 20 (clockwise in FIG. 3). Further, as shown in FIG. 3, the developing roller 510 of the yellow developing device 54 and the photosensitive member 20 are opposed to each other with a space therebetween. That is, the yellow developing device 54 develops the latent image formed on the photoconductor 20 in a non-contact state.

  When developing the latent image formed on the photoreceptor 20, the developing roller 510 is applied to the developing roller 510 by a developing bias generator 126 (see FIG. 7) which is an example of a voltage applying unit provided in the developing device holding unit drive control circuit. A developing bias in which a DC voltage and an AC voltage are superimposed is applied, and an alternating electric field is formed between the developing roller 510 and the photoconductor 20. The developing device holding unit drive control circuit is provided with a developing bias control circuit 125 that plays a role of controlling on / off of the developing bias and setting an appropriate developing bias value. The developing bias control circuit 125 also has a Vmax setting unit 125a, which is an example of a first voltage setting unit for setting the first voltage (Vmax), and a second voltage (Vmin) for adjusting the image density. And a Vmin setting unit 125b, which is an example of an image density adjustment unit for setting. Details of the developing bias will be described later.

  The seal member 520 prevents the toner T in the yellow developing device 54 from leaking out of the device, and collects the toner T on the developing roller 510 that has passed through the developing position into the developing device without being scraped off. The seal member 520 is a seal made of a polyethylene film or the like, and is pressed against the developing roller 510 by the elastic force of a seal urging member 524 made of a malt plane or the like provided on the opposite side to the developing roller 510 side.

The housing 540 is formed by welding a plurality of integrally molded housing portions. As shown in FIG. 3, the housing 540 has an opening 572 that communicates with the outside of the housing 540, the peripheral surface of the housing 540 faces the opening 572 from the outside of the housing 540. It is arranged with the part exposed. Further, a regulation blade 560 described later is also arranged in a state of facing the opening 572 from the outside of the housing 540.
The housing 540 forms a toner storage portion 530 that can store the toner T. The toner T accommodated in the toner accommodating portion 530 is manufactured by a pulverization method. The toner T has mother particles and an external additive externally added to the mother particles. The mother particles include materials such as a colorant, a charge control agent, a release agent (WAX), and a resin. The mother particles are produced by uniformly mixing the material with a Henschel mixer or the like, melt-kneading with a twin screw extruder, cooling, and then subjecting to a classification treatment through a coarse pulverization-fine pulverization process.

  The toner supply roller 550 is provided in the toner storage unit 530 described above, and supplies the toner T stored in the toner storage unit 530 to 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 toner storage unit 530, and the toner T stored in the toner storage unit 530 is supplied to the developing roller 510 by the toner supply roller 550 below the toner storage unit 530. The The toner supply roller 550 rotates around the central axis in a direction (clockwise in FIG. 3) opposite to the rotation direction of the developing roller 510 (counterclockwise in FIG. 3).

  The toner supply roller 550 has a function of supplying the toner T accommodated in the toner accommodating portion 530 to the developing roller 510, and peels off the toner T remaining on the developing roller 510 after the development from the developing roller 510. It also has a function.

  The regulating blade 560 applies a charge to the toner T carried on the developing roller 510 to negatively charge the toner T. The regulating blade 560 regulates the layer thickness of the toner T carried on the developing roller 510. The regulation blade 560 has a rubber part 560a and a rubber support part 560b. The rubber part 560a is made of silicon rubber, urethane rubber or the like, and the rubber support part 560b is a thin plate having spring properties such as phosphor bronze or stainless steel. The rubber part 560a is supported by a rubber support part 560b, and the rubber support part 560b is supported by being sandwiched between a pair of blade support metal plates 562 via the blade support metal plate 562. Is attached. Further, a blade back member 570 made of malt plane or the like is provided on the side opposite to the developing roller 510 side of the regulating blade 560.

  Further, as shown in FIG. 4, the end of the regulating blade 560 opposite to the side supported by the blade support metal plate 562, that is, the tip E is not in contact with the developing roller 510, and the tip E A portion (contact position C) that is a predetermined distance L from the contact with the developing roller 510. That is, the regulating blade 560 is not in edge contact with the developing roller 510 but is in contact with the belly. Further, the regulation blade 560 is disposed so that the tip E thereof faces the upstream side in the rotation direction of the developing roller 510 when viewed from the contact position C, and is in a so-called counter contact. When the distance L from the tip E to the contact position C (hereinafter also referred to as “projection amount L”) is large, the toner T is easily carried on the developing roller 510. Is big.

  In the yellow developing device 54 configured as described above, the toner supply roller 550 supplies the toner T accommodated in the toner accommodating portion 530 to the developing roller 510. The toner T supplied to the developing roller 510 reaches the abutting position of the regulating blade 560 as the developing roller 510 rotates, and when the toner T passes through the corresponding contacting position, an electric charge is applied and the layer thickness is regulated. Is done. The toner T on the developing roller 510 whose layer thickness is regulated reaches the developing position facing the photoconductor 20 by further rotation of the developing roller 510, and is formed on the photoconductor 20 under an alternating electric field at the developing position. Used for developing the latent image. The toner T on the developing roller 510 that has passed the developing position by further rotation of the developing roller 510 passes through the seal member 520 and is collected in the developing unit without being scraped off by the seal member 520.

  Further, each developing device 51, 52, 53, 54 stores various information related to the developing device such as the color information of the toner T accommodated in each developing device, the information regarding the protrusion amount L, and the information regarding the surface roughness Rz. For example, a non-volatile storage memory (hereinafter also referred to as a developing device side memory) 51a, 52a, 53a, 54a such as a serial EEPROM.

  The developing device side memories 51a, 52a, 53a, 54a include developing device side connectors 51b, 52b, 53b, 54b provided on one side surface of the developing device, and an apparatus main body provided on the apparatus main body side (printer side). The side connector 34 is in contact with each other when necessary, and is electrically connected to the unit control unit 102 of the main body control unit 100.

=== Overview of Developer Holding Unit ===
Next, an outline of the developing device holding unit 50 will be described with reference to FIGS. 5A to 5C.
The developing device holding unit 50 has a rotation shaft 50e located at the center thereof, and a support frame 55 for holding the developing device is fixed to the rotation shaft 50e. The rotation shaft 50e serves as a housing of the printer 10. It spans between two frame side plates (not shown) formed, and both ends thereof are supported. In addition, the axial direction of the rotating shaft 50e intersects the vertical direction.
The support frame 55 includes four attaching / detaching portions 50a, 50b, 50c, and 50d in which the four color developing devices 51, 52, 53, and 54 are detachably attached around the rotating shaft 50e in the circumferential direction. It is provided at 90 ° intervals.
A pulse motor (not shown) is connected to the rotary shaft 50e. By driving the pulse motor, the support frame 55 can be rotated to position the four phenomenon devices 51, 52, 53, 54 at predetermined positions. It is like that.

5A to 5C show three stop positions of the rotating developing device holding unit 50, and FIG. 5A shows the standby position when waiting for execution of image formation. FIG. 5B shows a home position (hereinafter referred to as “HP position”) that is a stop position serving as a reference position in the rotation direction of FIG. 5B, and a developer-side connector 54b of the yellow developer 54 attached to the developer holding unit 50; FIG. 5C shows the attachment / detachment position of the yellow developing device 54, and the connector attachment / detachment position facing the apparatus body-side connector 34 provided on the apparatus body side.
5B and 5C, the connector attaching / detaching position and the developing device attaching / detaching position are shown with respect to the yellow developing device 54, but the position where the developing device holding unit 50 is rotated by 90 degrees is the position of each developing device. A connector attach / detach position and a developer attach / detach position.

  First, the HP position shown in FIG. 5A will be described. On one end side of the rotation shaft 50e of the developing device holding unit 50, an HP detection unit 31 (FIG. 7) for detecting the HP position is provided. The HP detection unit 31 includes a signal generation disk fixed to one end of the rotating shaft 50e, and an HP sensor including a photo interrupter provided with a light emitting unit and a light receiving unit. The peripheral part of the disk is arranged so as to be positioned between the light emitting part and the light receiving part of the HP sensor, and when the slit part formed in the disk moves to the detection position of the HP sensor, the output from the HP sensor The signal changes from “L” to “H”. The HP position of the developing device holding unit 50 is detected based on the change in the signal level and the number of pulses of the pulse motor, and the developing device can be positioned at the developing position of each developing device on the basis of the HP position. Has been.

  FIG. 5B shows a connector attaching / detaching position of the yellow developing device 54 in which the pulse motor is rotated by a predetermined number of pulses from the HP position. At this connector attaching / detaching position, the developing device side connector 54b of the yellow developing device 54 attached to the developing device holding unit 50 and the apparatus main body side connector 34 provided on the apparatus main body side face each other, and these connectors are in contact with each other. It is possible to make contact or separation.

Further explanation will be given with reference to FIGS. 6A and 6B. FIG. 6A is a diagram related to the separation position, and FIG. 6B is a diagram related to the contact position.
FIG. 6A shows a state where the apparatus main body side connector 34 and the developing device side connector 54b of the yellow developing device 54 are separated from each other. The apparatus main body side connector 34 is configured to be movable toward and away from the yellow developing unit 54, and moves in the direction approaching the yellow developing unit 54 (the direction of the arrow shown in FIG. 6B) as necessary. As a result, as shown in FIG. 6B, the apparatus main body side connector 34 abuts against the developing device side connector 54 b of the yellow developing device 54, and the developing device side memory 54 a attached to the yellow developing device 54 is connected to the control unit 100. The unit controller 102 is electrically connected, and communication is performed between the developing device side memory 54a and the apparatus main body.

  On the other hand, the apparatus main body side connector 34 moves away from the yellow developing device 54 from the state in which the apparatus main body side connector 34 and the developing device side connector 54b of the yellow developing device 54 shown in FIG. 6B) (in the direction opposite to the arrow direction). As a result, as shown in FIG. 6A, the apparatus main body side connector 34 is separated from the developing device side connector 54 b of the yellow developing device 54.

  The movement of the apparatus main body side connector 34 is realized by, for example, a mechanism (not shown) including a pulse motor, a plurality of gears connected to the pulse motor, and an eccentric cam connected to the gear. That is, when the pulse motor is rotated by a predetermined number of pulses, the mechanism moves the apparatus main body side connector 34 by a distance corresponding to the pulse number from a predetermined separation position, and the apparatus main body side connector 34 is moved. It is positioned at a predetermined contact position. Conversely, when the pulse motor is reversely rotated by a predetermined number of pulses, the mechanism moves the device body side connector 34 by a distance corresponding to the number of pulses from a predetermined contact position, and the device body side The connector 34 is positioned at a predetermined separation position.

  Further, the connector attaching / detaching position with respect to the yellow developing unit 54 becomes the developing position of the cyan developing unit 52 with the developing roller 510 of the cyan developing unit 52 and the photosensitive member 20 facing each other. That is, the connector attaching / detaching position of the developing device holding unit 50 related to the yellow developing device 54 is the developing position of the developing device holding unit 50 related to the cyan developing device 52. Further, when the pulse motor rotates the developing device holding unit 50 by 90 ° counterclockwise, the connector attaching / detaching position of the black developing device 51 and the developing position of the yellow developing device 54 are obtained, and the developing device holding unit 50 is rotated by 90 °. Each time it is done, it becomes the connector attaching / detaching position and developing position of each developing device.

In addition, one of the two frame side plates that support the developing device holding unit 50 and form the housing of the printer 10 can be opened and closed with a detachable opening 37 through which one developing device can pass and a detachable opening 37. And an inner cover (not shown) for covering. When the developing device holding unit 50 is rotated and each developing device is stopped at the set developing device attaching / detaching position, the attaching / detaching dedicated port 37, as shown in FIG. 5C, corresponds to the corresponding developing device (here, yellow). Only the developing device 54) is formed at a position where it can be pulled out and removed in the direction along the rotation shaft 50e. In addition, the attachment / detachment port 37 is formed to be slightly larger than the outer shape of the developing device. At the developing device attaching / detaching position, not only the developing device is removed, but also a new developing device is installed in the direction along the rotation shaft 50e through the attaching / detaching port 37. The developing device can also be attached to the support frame 55 by making it enter. While the developing device holding unit 50 is located at a position other than the developing device attaching / detaching position, the attaching / detaching of the developing device is restricted by the frame side plate.
A locking mechanism (not shown) is provided in order to securely position and fix the developing device holding unit 50 at the above-described position.

=== Overview of Control Unit ===
Next, the configuration of the control unit 100 will be described with reference to FIG. FIG. 7 is a block diagram showing the control unit 100 of the printer 10.

  The controller unit 101 includes a CPU 111, an interface 112 for connecting to a computer (not shown), an image memory 113 for storing image signals and the like input from the computer, electrically rewritable EEPROMs 114a and RAM 114b, And a controller unit side memory 114 composed of a program ROM or the like having a control program. Various information such as an image signal is sent to the controller unit 101 from a computer connected to the printer 10.

  The controller unit 101 converts RGB data of red, green, and blue as image signals transmitted from a computer or the like into YMCK image data of yellow, magenta, cyan, and black, and the converted YMCK image data is stored in the image memory 113. It has a function to memorize. Furthermore, the controller unit 101 has a function of sending various information to a connected computer.

  The unit controller 102 includes a CPU 120, an electrically rewritable EEPROM 116a, RAM, a unit controller memory 116 including a program ROM having various control programs, and each unit (charging unit 30, The exposure unit 40, the primary transfer unit 60, the cleaning unit 75, the secondary transfer unit 80, the fixing unit 90, the display unit 95), and drive control circuits for driving and controlling the developing device holding unit 50 are included.

  The CPU 120 is electrically connected to each drive control circuit and controls each drive control circuit based on a control signal from the CPU 111 of the controller unit 101. That is, the unit control unit 102 receives signals from sensors and the like included in each unit, thereby detecting the state of each unit and the developing device holding unit 50, and based on a signal input from the controller unit 101. Each unit and the developer holding unit 50 are controlled.

  The CPU 120 is connected to a non-volatile storage element (hereinafter referred to as a main body side memory) 122 such as a serial EEPROM via a serial interface (I / F) 121. The main body side memory 122 stores data necessary for device control. The CPU 120 is connected not only to the main body side memory 122 but also to the developing device side memories 51 a, 52 a, 53 a, 54 a provided in the developing devices 51, 52, 53, 54 via the serial interface 121. In addition, data can be transferred between the main body side memory 122 and the developing device side memories 51a, 52a, 53a, 54a, and chip select can be made to each developing device side memory 51a, 52a, 53a, 54a via the input / output port 123. The signal CS can be input. The CPU 120 is also connected to the HP detection unit 31 via the input / output port 123.

  The CPU 120 also connects the developing device side memories 51a, 52a, 53a, when the connector of any of the developing devices arranged at the connector attaching / detaching position and the apparatus body side connector 34 among the developing devices are connected. It becomes possible to communicate with 54a. Then, various information on the developing device is acquired from the developing device side memories 51a, 52a, 53a, 54a of the developing device connected to the apparatus main body side connector 34. The information on the developing device is, for example, the color information of the toner stored in the mounted developing device, the information on the protrusion amount L, the information on the surface roughness Rz, and the like. Is stored in a predetermined area of the main body side memory 122 corresponding to each developing device.

  Further, when the developing device is removed from the attaching / detaching portion, the CPU 120 stores information on the protrusion amount L stored in the main body side memory 122 in the developing device side memories 51a, 52a, 53a, 54a of each developing device, and the surface roughness. Information on the length Rz is stored.

=== About development bias ===
The developing bias applied from the developing bias generator 126 to the developing roller 510 will be described with reference to FIG. FIG. 8 is a diagram showing a waveform of the developing bias.

  The developing bias generator 126 applies a rectangular developing bias as shown in FIG. 8 to the developing roller 510 for developing the latent image. Specifically, the developing bias generator 126 uses a first voltage (Vmax) for directing the toner T from the developing roller 510 to the photoconductor 20 and the photoconductor 20 to the developing roller 510 for developing the latent image. A second voltage (Vmin) for directing the toner T toward the developing roller 510 is alternately applied to the developing roller 510.

  When the developing bias generator 126 applies Vmax to the developing roller 510, the toner T carried on the developing roller 510 flies toward the photosensitive member 20 and adheres to the photosensitive member 20. When Vmax is applied to the developing roller 510, the potential of the developing roller 510 by Vmax (for example, −1250V) and the potential of the photosensitive member 20 on which the latent image is formed (for example, the potential of the image portion is −50V). The electric field is generated by the difference between the potential of the non-image area and -530V. The negatively charged toner T carried on the developing roller 510 flies toward the photoconductor 20 by the force of the electric field and adheres to the photoconductor 20. Note that the greater the absolute value of Vmax, the greater the force due to the electric field, so the amount of toner T adhering to the photoreceptor 20 increases.

  When the developing bias generator 126 applies Vmin to the developing roller 510, the toner T adhering to the photoreceptor 20 flies toward the developing roller 510 and returns to the developing roller 510. When Vmin is applied to the developing roller 510, the potential of the developing roller 510 by Vmin (for example, 300V) and the potential of the photosensitive member 20 on which the latent image is formed (for example, the potential of the image portion is −50V, An electric field is generated due to the difference between the non-image portion potential of −530 V). The negatively charged toner T adhering to the photoconductor 20 flies toward the developing roller 510 by the force of the electric field and returns to the developing roller 510. The toner T returning to the developing roller 510 is a part of the toner T adhering to the photoconductor 20, and the toner T adhering to the photoconductor 20 without returning to the developing roller 510 is used for developing the latent image. Note that the greater the absolute value of Vmin, the greater the force due to the electric field, so the amount of toner T returning to the developing roller 510 increases.

  Before the developing bias generator 126 applies Vmax and Vmin to the developing roller 510, the toner T carried on the developing roller 510 does not contact the photoconductor 20. Therefore, when Vmax and Vmin are not applied to the developing roller 510, the latent image is not developed.

  Further, as shown in FIG. 8, the time during which the developing bias generator 126 applies Vmax to the developing roller 510 is 133 (μs), and the developing bias generator 126 applies Vmin to the developing roller 510. The time spent is 200 (μs).

=== Operation of Printer 10 ===
The operation of the printer 10 when adjusting the image density to form an image on a recording medium will be described with reference to FIG. FIG. 9 is a flowchart for explaining the operation of the printer 10.

  Various operations of the printer 10 described below are mainly realized by the controller unit 101 or the unit control unit 102 in the printer 10. In particular, in the present embodiment, it is realized by the CPU processing a program stored in the program ROM. And this program is comprised from the code | cord | chord for performing the various operation | movement demonstrated below.

  First, when the developing device is attached to the printer main body 10 a and the printer 10 is turned on, the Vmax setting unit 125 a provided in the unit control unit 102 displays the conveyance amount information regarding the conveyance amount of the toner T by the developing roller 510. Based on this, Vmax is set for each developing device (S102). The Vmax setting unit 125a sets the absolute value of Vmax small when the conveyance amount by the developing roller 510 is large, and sets the absolute value of Vmax large when the conveyance amount by the developing roller 510 is small. The Vmax is set when a new developing device is mounted on the printer main body 10a. Once Vmax is set for the developing device, the Vmax setting operation is not performed until another developing device is mounted. A method for setting Vmax based on the carry amount information will be described in detail later.

  Next, in order to adjust the density of the image formed on the recording medium, the Vmin setting unit 125b provided in the unit control unit 102 sets Vmin based on the detection result of the density of the patch image by the patch sensor PS. (S104). At this time, the Vmin setting unit 125b changes only Vmin out of Vmax and Vmin, that is, maintains Vmax set by the Vmax setting unit 125a in S102 and changes Vmin to the recording medium. Adjust the density of the image to be formed.

  This will be described more specifically. As shown in FIG. 10, the Vmin setting unit 125b adjusts the image density by changing Vmin (for example, changing from 300 V to 290 V) while maintaining Vmax at −1250 (V). Since only Vmin changes, the difference between Vmax and Vmin (Vpp in FIG. 10) is not constant. FIG. 10 is a schematic diagram showing changes in Vmax and Vmin.

  A method of setting Vmin based on the detection result of the density of the patch image by the patch sensor PS will be described in detail later.

  Next, when an image signal from a host computer (not shown) is input to the controller unit 101 of the printer 10 via the interface (I / F) 112, the control of the unit control unit 102 based on a command from the controller unit 101 is performed. As a result, the developing roller provided in the photosensitive member 20, the developing devices 51, 52, 53, and 54, and the intermediate transfer member 70 are rotated. Then, the unit controller 102 controls the charging unit 30 to charge the photoconductor 20 (S106). The charging unit 30 sequentially charges the rotating photoreceptor 20 at the charging position.

  Next, the unit controller 102 controls the exposure unit 40 to form a latent image on the charged photoconductor 20 (S108). 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. . Further, the developing device holding unit 50 positions the yellow developing device 54 containing yellow (Y) toner at a developing position facing the photoconductor 20.

  Next, the developing bias generator 126 provided in the unit controller 102 alternately develops Vmax set by the Vmax setting unit 125a in S102 and Vmin set by the Vmin setting unit 125b in S104. (S110). The developing bias generator 126 alternately applies Vmax having a value of −1250 (V) and Vmin having a value of 290 (V) to the developing roller 510. As a result, the latent image formed on the photoconductor 20 reaches the developing position as the photoconductor 20 rotates, and is developed with toner by the developing roller 510. As a result, a toner image is formed on the photoreceptor 20.

  Next, the unit controller 102 controls the primary transfer unit to transfer the toner image formed on the photoconductor 20 to the intermediate transfer body 70 (S112). The 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 is applied to the primary transfer unit 60. During this time, the secondary transfer unit 80 is separated from the intermediate transfer member 70.

  By repeating the above processing (S102 to S112) for the second color, the third color, and the fourth color, toner images of four colors corresponding to the respective image signals are transferred to the intermediate transfer body 70. Overlaid and transferred. 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 recording medium by the secondary transfer unit 80. Thereby, an image is formed on the recording medium (S114). The recording 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 recording medium is heated and pressurized by the fixing unit 90 and fused to the recording medium. On the other hand, after the primary transfer position has passed, the toner adhering to the surface of the photoreceptor 20 is scraped off by the cleaning blade 76 supported by the cleaning unit 75, and is charged for forming the next latent image. Prepare. The toner that has been scraped off is collected by a residual toner collecting unit provided in the cleaning unit 75.

=== Regarding Vmax Setting Method Based on Carriage Amount Information ===
A method of setting Vmax based on the carry amount information will be described with reference to FIG. FIG. 11 is a flowchart showing a method for setting Vmax.

  The setting of Vmax is started in a state in which the developing device is attached to the attaching / detaching portion at the developing device attaching / detaching position (FIG. 5C). The unit controller 102 rotates the developing device holding unit 50 to sequentially move the four attachment / detachment portions to the connector attachment / detachment position (FIG. 5B) (S302).

  Next, the unit control unit 102 moves the attachment main body side connector 34, and when the developing device is attached to the attaching / detaching portion disposed at the connector attaching / detaching position, the unit control unit 102 stores the developing device in the developing device side memory of the developing device. The transport amount information and the like that have been acquired are acquired (S304). For example, when the yellow developing device 54 is attached to the attaching / detaching portion 50d disposed at the connector attaching / detaching position, the unit control unit 102 causes the apparatus main body side connector 34 to abut against the developing device side connector 54b, and the yellow developing device 54 is attached. Information stored in the developing device side memory 54a of the developing device 54 is acquired. Then, the unit controller 102 reads the conveyance amount information (information about the protruding amount L of the regulating blade 560, surface roughness information about the surface roughness Rz of the developing roller 510), and the like, in a predetermined area of the main body side memory 122. Stored for each developer.

  Next, the unit control unit 102 reads the conveyance amount information read from the developing device side memory and stored in the main body side memory 122, and the Vmax setting table stored in the unit control unit side memory 116 (FIG. 12). , Vmax is determined (S306). For example, when the protruding amount L is 1.0 (mm) and the surface roughness Rz is 5.0 (μm) as the transport amount information, the unit control unit 102 sets Vmax to −1300 (V). And decide. Then, the unit control unit 102 stores Vmax determined for each developing device in a predetermined area of the main body side memory 122. FIG. 12 shows a Vmax setting table.

  As shown in FIG. 12, when the transport amount is large (when the surface roughness Rz is large or when the protrusion amount L is large), the absolute value of Vmax is small and when the transport amount is small (surface roughness Rz). If the protrusion amount L is small), the absolute value of Vmax is large. For example, when the surface roughness Rz is 5.5 (mm) and the protrusion amount L is 1.1 (mm), Vmax is −1250 (V) and the surface roughness Rz is 4.5 ( mm) and the protrusion amount L is 0.9 (mm), Vmax is -1350 (V).

  Next, the Vmax setting unit 125a sets the determined Vmax (DC voltage, AC voltage) for each developing device (S308). For example, the Vmax setting unit 125a sets Vmax to −1250 (V) in the case of a developing device having a protrusion amount L of 1.0 (mm) and a surface roughness Rz of 5.0 (μm). To do.

=== Vmin Setting Method ===
As described above, the printer 10 executes a control operation (Vmin setting operation) for adjusting the image density at a predetermined timing. Here, an example of the control operation will be described with reference to FIGS. 13 and 14. FIG. 13 is a flowchart showing a method for setting Vmin. FIG. 14 is a schematic diagram illustrating a state in which a patch image is formed on the intermediate transfer body 70. Various operations of the printer 10 described below are mainly realized by the controller unit 101 or the unit control unit 102 in the printer 10. In particular, in the present embodiment, it is realized by the CPU processing a program stored in the program ROM. And this program is comprised from the code | cord | chord for performing the various operation | movement demonstrated below.

  First, the printer 10 develops a patch image (step S502). 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 the exposure position as the photoconductor 20 rotates, and the exposure unit 40 causes the patch latent image corresponding to the information relating to the patch image of the first color, for example, yellow Y, to be displayed in the area. Formed. The patch latent image formed on the photoconductor 20 reaches the developing position as the photoconductor 20 rotates, and is developed with yellow toner by the yellow developing device 54. At this time, development is performed while changing Vmin of the developing bias applied by the developing bias generator 126, that is, while changing the DC voltage and the AC voltage. As a result, a patch image is formed on the photoreceptor 20.

The patch 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 (step S504). Thereby, as shown in FIG. 14, a plurality of patch images having different densities are arranged on the intermediate transfer body 70.
Each time the patch image on the intermediate transfer body 70 reaches the position facing the patch sensor PS due to the rotation of the intermediate transfer body 70, the density of the patch image is detected by the patch sensor PS (step S506).
Then, when the density of all the patch images is detected, based on the density detection result, in other words, by comparing the detected density of each patch image with the desired image density, the optimum Vmin, That is, the optimum DC voltage and AC voltage are determined (step S508). The determined Vmin is stored in a predetermined area of the main body side memory 122 for each developing device.
Next, the determined Vmin is set by the above-described Vmin setting unit 125b so that the development after the control operation can be performed with an optimum developing bias (step S510).

  The residual toner T constituting the patch image whose density has been detected is sequentially cleaned by an intermediate transfer member cleaning unit (not shown).

  The above process is sequentially executed for each developing device for the second color, the third color, and the fourth color, so that the optimum Vmin is set for each color and the image density is adjusted. The control operation is completed (step S512).

  In the above, a plurality of patch images having different densities are formed. However, the present invention is not limited to this. For example, a single patch image in which the density gradually changes may be formed. Good.

=== About selective development ===
As described above, when a developing bias is applied to the developing roller 510, the toner T carried on the developing roller 510 flies toward the photosensitive member 20 and adheres to the photosensitive member 20, thereby developing the latent image. Is done. By the way, depending on the magnitude of the developing bias, a part of the toner T carried on the developing roller 510 does not fly toward the photoconductor 20, and so-called selective development in which the latent image is not properly developed occurs.

  The reason why the selective development occurs will be described. The toner T carried on the developing roller 510 is charged by being charged by the regulating blade 560. At this time, the charge amount of the toner T is not uniform, and the toner T having a different charge amount is carried on the developing roller 510. On the other hand, the toner T is carried on the developing roller 510 by a mirror image force acting between the developing roller 510 and the like. For this reason, when the absolute value of Vmax applied to the developing roller 510 is small, the force for directing the toner T from the developing roller 510 to the photosensitive member 20 is smaller than the mirror image force or the like. The roller 510 cannot be directed to the photoconductor 20.

The relationship between development bias and selective development will be described more specifically using measurement results.
First, the relationship between the development bias and the selective development when only the development bias Vmax is changed will be described with reference to FIGS. 15A and 15B. FIG. 15A is a graph showing the relationship between the charge amount of the toner T adhering to the photoreceptor 20 and the weight of the toner T when only Vmax is changed. FIG. 15B is a graph showing the relationship between the charge amount of the toner T adhering to the photoconductor 20 and the number of toners T when only Vmax is changed.
Here, four developing biases C 1, C 2, C 3, and C 4 having different Vmax are applied to the developing roller 510. The developing bias C1 has a Vmax of -1350 (V) and a Vmin of 360 (V). The developing bias C2 has a Vmax of −1250 (V) and Vmin of 360 (V). The development bias C3 has a Vmax of -1040 (V) and a Vmin of 360 (V). The development bias C4 has a Vmax of −900 (V) and a Vmin of 360 (V).

As shown in FIGS. 15A and 15B, in the case of developing biases C1, C2, C3, and C4, the amount of toner T having a charge amount of about −5 (μC / g) is large on the photoreceptor 20. The amount of toner T (hereinafter referred to as “highly charged toner”) having a charge amount of around −20 (μC / g) to the photoreceptor 20 is small.
In the case of the developing biases C3 and C4, the amount of adhesion of the highly charged toner T to the photoconductor 20 is smaller than in the case of the developing biases C1 and C2. That is, in the case of the developing biases C3 and C4, the highly charged toner T carried on the developing roller 510 hardly jumps toward the photoconductor 20, and selective development occurs. Further, when the developing biases C3 and C4 are compared, selective development is likely to occur when the developing bias C4 has a small absolute value of Vmax. Therefore, in order to prevent selective development, it is effective to increase the absolute value of the development bias Vmax.

Next, the relationship between the development bias and the selective development when only the development bias Vmin is changed will be described with reference to FIGS. 16A and 16B. FIG. 16A is a graph showing the relationship between the charge amount of the toner T adhering to the photoreceptor 20 and the weight of the toner T when only Vmin is changed. FIG. 16B is a graph showing the relationship between the charge amount of the toner T adhering to the photoreceptor 20 and the number of toners T when only Vmin is changed.
Here, three developing biases D1, D2, and D3 having different Vmin are applied to the developing roller 510. The developing bias D1 has a Vmax of -1350 (V) and a Vmin of 150 (V). The development bias D2 has a Vmax of -1350 (V) and a Vmin of 360 (V). The development bias D3 has a Vmax of -1350 (V) and a Vmin of 480 (V).
Then, as shown in FIGS. 16A and 16B, there is almost no difference in the amount of the highly charged toner T adhering to the photoconductor 20 with the developing biases D1, D2, and D3. For this reason, even when the development bias Vmin is changed, selective development is unlikely to occur.

=== Unevenness on the recording medium ===
In some cases, unevenness in density may occur in an image formed on a recording medium. Therefore, in the following, the cause of occurrence of shading in the image will be described with reference to FIGS. FIG. 17 is a diagram illustrating a state in which the toner T adheres to the recording medium S non-uniformly. FIG. 18 is a graph showing the relationship between the magnitude of Vmin and the image density on the recording medium when Vmax is changed. FIG. 19 is a graph showing the relationship between the magnitude of Vmin and the density of the image on the recording medium when the amount of toner T transported by the developing roller 510 is changed.

  As described above, as the absolute value of Vmin increases, the amount of toner T that returns from the photoreceptor 20 to the developing roller 510 increases. For this reason, when the absolute value of Vmin is large, the amount of toner T adhering to the photoreceptor 20 is reduced, so that the amount of toner T constituting the image formed on the recording medium is reduced, and the density of the image is reduced. Tend to be smaller. On the other hand, when the absolute value of Vmin is small, the image density tends to increase for the same reason as described above. However, when the absolute value of Vmin is smaller than a predetermined value (also referred to as “density reduction value”), the image density does not increase, and the image density gradually decreases. Then, when Vmin becomes a value close to the density reduction value (V1 shown in FIG. 18) in order to obtain a target density that is a desired density, unevenness in density of the image occurs.

  The reason why unevenness of the image density occurs when Vmin becomes a value close to the density reduction value will be described. As described above, since Vmax and Vmin are alternately applied to the developing roller 510, the toner T vibrates between the developing roller 510 and the photoconductor 20. As the toner T vibrates, the layer of the toner T adhering to the photoreceptor 20 becomes uniform. However, when the absolute value of Vmin is small, it is difficult for the toner T to fly from the photoconductor 20 toward the developing roller 510, and the toner T does not vibrate properly. It becomes uniform. When an image is formed on the recording medium in such a state, the toner T adheres unevenly to the recording medium S as shown in FIG.

By the way, even if the magnitude of Vmin is the same, the density of the image on the recording medium is different when the magnitude of Vmax is different or when the transport amount of the toner T by the developing roller 510 is different. This will be described more specifically.
As shown in FIG. 18, the larger the absolute value of Vmax, the higher the image density. This is because when the absolute value of Vmax is large, the amount of toner T traveling from the developing roller 510 toward the photoconductor 20 increases. Therefore, when the absolute value of Vmax is increased, the absolute value of Vmin can be increased when the desired density (target density) is achieved, and unevenness in the density of the image can be prevented.

  Further, as shown in FIG. 19, the image density is higher when the amount of toner T transported by the developing roller 510 is larger. This is because when the amount of toner T conveyed by the developing roller 510 is large, the amount of toner T carried on the developing roller 510 increases, so that the amount of toner T directed from the developing roller 510 toward the photoconductor 20 increases. . Therefore, when the amount of toner T transported by the developing roller 510 is large, the absolute value of Vmin can be increased when the desired density (target density) is obtained, and uneven density of the image can be prevented. Become.

=== Function of Development Bias of this Embodiment ===
As described above, the Vmax setting unit 125a sets Vmax based on the transport amount information, the Vmin setting unit 125b maintains the Vmax set by the Vmax setting unit 125a, and changes the Vmin to perform recording. The density of the image formed on the medium is adjusted. As a result, it is possible to prevent unevenness in the density of the image and to prevent an increase in fog and scattering of the toner T. This will be described in detail below.
In consideration of preventing so-called selective development, it is effective to adjust the image density by fixing Vmax so as to increase its absolute value and changing only Vmin.
However, when the image density is adjusted by changing only Vmin, the value that Vmin can take is wide. In such a case, in order to adjust to a desired density (target density), the absolute value of Vmin may be small. When the magnitude of Vmin becomes a value close to the density reduction value (V1 shown in FIG. 18), unevenness in the density of the image occurs. If the fixed absolute value of Vmax is too large, the toner T traveling from the developing roller 510 toward the photoconductor 20 is excessively increased, and fogging on the non-image portion of the photoconductor 20, the developing roller 510 and the photosensitive roller 20 are exposed. There is a possibility that the scattering of the toner T with the body 20 may increase.

Therefore, in the present embodiment, the Vmax setting unit 125a sets Vmax according to the transport amount of the toner T by the developing roller 510. This will be described more specifically.
The Vmax setting unit 125a sets the absolute value of Vmax to a small value when the transport amount of the toner T by the developing roller 510 is large. When the transport amount is large, fogging and toner T scattering are likely to increase. Therefore, it is desirable that the absolute value of Vmax be small. On the other hand, even if the absolute value of Vmax is made small, unevenness in the density of the image hardly occurs because the carry amount is large. Therefore, when the transport amount of the toner T by the developing roller 510 is large, by reducing the absolute value of Vmax, it is possible to prevent an increase in fogging and scattering of the toner T, while unevenness in the density of the image. Is unlikely to occur.

  The Vmax setting unit 125a sets the absolute value of Vmax to a large value when the transport amount of the toner T by the developing roller 510 is small. When the transport amount is small, unevenness in density is likely to occur, so it is desirable that the absolute value of Vmax be large. On the other hand, even if the absolute value of Vmax is increased, since the transport amount is small, the fog and the scattering of the toner T are unlikely to increase. Therefore, when the transport amount of the toner T by the developing roller 510 is small, increasing the absolute value of Vmax makes it possible to prevent unevenness in the density of the image, while increasing fogging and scattering of the toner T. It is hard to do.

  From the above, when the Vmax setting unit 125a sets Vmax based on the conveyance amount information regarding the conveyance amount of the toner T by the developing roller 510, an appropriate Vmax is set according to the conveyance amount when adjusting the image density. Therefore, it is possible to prevent unevenness in the density of the image and to prevent an increase in fogging and scattering of the toner T.

=== Other Embodiments ===
The image forming apparatus and the like according to the present invention have been described above based on the above embodiment. However, the above embodiment of the present invention is for facilitating understanding of the present invention and limits the present invention. is not. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.

  The present invention includes a photosensitive member 20 (image carrier), a developing roller 510 (developer carrier), a transfer unit (primary transfer unit 60, intermediate transfer member 70, secondary transfer unit 80), and a developing bias generator. The present invention relates to a printer 10 (image forming apparatus) having 126 (voltage application unit), a Vmax setting unit 125a (first voltage setting unit), and a Vmin setting unit 125b (image density adjustment unit).

  In the above embodiment, the intermediate transfer type full color laser beam printer has been described as an example of the image forming apparatus. However, the present invention is not limited to the intermediate transfer type, but a full color laser beam printer, a monochrome laser beam printer, a copying machine, a facsimile machine. The present invention can be applied to various image forming apparatuses.

  In the above-described embodiment, the image forming apparatus including the rotary developing device has been described as an example. However, the present invention is not limited to this. For example, the present invention can be applied to an image forming apparatus provided with a tandem developing device.

  In the above embodiment, the photoconductor as the image carrier has been described as a configuration in which the photosensitive layer is provided on the outer peripheral surface of the cylindrical conductive base material, but the present invention is not limited to this. For example, a so-called photosensitive belt configured by providing a photosensitive layer on the surface of a belt-like conductive substrate may be used.

Further, in the above embodiment, as shown in FIG. 3, the printer 10 is in contact with the developing roller 510, and the regulating blade 560 (layer thickness regulating) for regulating the layer thickness of the toner T carried on the developing roller 510. Member). Further, the transport amount of the toner T by the developing roller 510 is the transport amount after the layer thickness is regulated by the regulation blade 560.
However, it is not limited to the above configuration. For example, the printer 10 may not have the restriction blade 560.
However, when the printer 10 has the regulating blade 560, the layer thickness of the toner T carried on the developing roller 510 is regulated to be constant, and the latent image is developed by the toner T. Therefore, the transport amount of the toner T by the developing roller 510 after the layer thickness is regulated by the regulating blade 560 (hereinafter also referred to as “the regulated transport amount”) is used as the carry amount of the toner T by the developing roller 510. It is valid. Therefore, when the Vmax setting unit 125a sets Vmax based on the conveyance amount information related to the post-regulation conveyance amount, it effectively prevents unevenness of the image and prevents an increase in fogging and scattering of the toner T. It becomes possible. Therefore, the above embodiment is more desirable.

  Furthermore, in the above embodiment, as shown in FIG. 4, the regulating blade 560 is configured such that the tip E of the regulating blade 560 that contacts the developing roller 510 abuts against the developing roller 510 of the regulating blade 560. It is assumed that it is provided so as to face the upstream side in the rotation direction of the developing roller 510 when viewed from the contact position C (the regulating blade 560 is in contact with the developing roller 510 at a so-called belly contact). Further, as shown in FIG. 12, as the conveyance amount information, distance information (protrusion amount L information) regarding the distance L (protrusion amount L) from the tip E to the contact position C, and the surface roughness Rz of the developing roller 510. Surface roughness information was used.

However, it is not limited to the above configuration. For example, the conveyance amount information may be either one of the protrusion amount L information and the surface roughness information. When the protruding amount L changes, the amount of toner T carried on the developing roller 510 changes, so the amount of toner T conveyed by the developing roller 510 also changes. Therefore, when the carry amount information is the protrusion amount L information, the carry amount of the toner T by the developing roller 510 can be grasped easily and appropriately. On the other hand, when the surface roughness Rz of the developing roller 510 changes, the transport amount of the toner T by the developing roller 510 also changes. Therefore, when the conveyance amount information is surface roughness information, the conveyance amount of the toner T by the developing roller 510 can be grasped easily and appropriately.
Further, the transport amount information may be information on the actual transport amount of the toner T by the developing roller 510. The actual transport amount is calculated as follows. The toner T carried on the developing roller 510 is transferred to an adhesive tape or the like, and the transport amount is calculated from the weight of the transferred toner T. Alternatively, the thickness of the toner T layer carried on the developing roller 510 is measured using a laser measuring device or the like, and the transport amount is calculated from the measured thickness.
Further, the regulating blade 560 may be in edge contact with the developing roller 510.

Further, in the above embodiment, as shown in FIGS. 1 and 3, the printer 10 is detachable from the printer main body 10 a (image forming apparatus main body), and includes a developing roller 510 and is carried by the developing roller 510. The developing devices 51, 52, 53, and 54 (developing devices) for containing the toner T are included. Further, the developing devices 51, 52, 53, and 54 store the transport amount information (protrusion amount L information and surface roughness information) related to the transport amount of the toner T accommodated in the developing device. 51a, 52a, 53a, 54a (developing device storage unit) are provided. Furthermore, the Vmax setting unit 125a sets Vmax based on the transport amount information read from the developing device side memories 51a, 52a, 53a, and 54a.
However, it is not limited to the above configuration. For example, the developing devices 51, 52, 53, and 54 are not provided with the developing device-side memories 51 a, 52 a, 53 a, and 54 a, and a user or the like may input conveyance amount information to the printer 10.

Further, in the above-described embodiment, as shown in FIG. 1, the transfer unit has an intermediate transfer serving as a medium when transferring a toner image (developer image) formed on the photoreceptor 20 to a recording medium (medium). The body 70 (transfer mediating member) is provided. The transfer unit transfers the toner image formed on the photoconductor 20 to the intermediate transfer body 70 and transfers the toner image transferred to the intermediate transfer body 70 to a recording medium to form an image. It was decided. Further, as shown in FIG. 1, the printer 10 detects a density of a patch image (test pattern) formed on the intermediate transfer body 70 in order to adjust the density of the image formed on the recording medium. A density detecting member). Further, the Vmin setting unit 125b changes Vmin based on the detection result of the density of the patch image by the patch sensor PS.
However, it is not limited to the above configuration. For example, the patch sensor PS may detect the density of the patch image formed on the photoconductor 20.

Furthermore, in the above embodiment, the developing roller 510 is made of metal, but the present invention is not limited to this. For example, the developing roller 510 may be made of a nonmetal.
However, when the developing roller 510 is made of metal, the mirror image force acting between the toner T and the developing roller 510 is stronger than when the developing roller 510 is made of non-metal. In such a case, in order to prevent selective development, the absolute value of Vmax is set large, and fogging and toner T scattering are likely to increase. Therefore, when the developing roller 510 is made of metal, an effect that it is possible to prevent an increase in fogging and scattering of the toner T is more effectively achieved. Therefore, the above embodiment is more desirable.

Furthermore, in the above embodiment, the toner T is manufactured by the pulverization method, but the present invention is not limited to this. For example, the toner may be manufactured by a polymerization method.
However, when the toner is manufactured by a pulverization method, the charge distribution of the toner is wider than when the toner is manufactured by a polymerization method. In such a case, in order to prevent selective development, the absolute value of Vmax is set large, and fogging and toner T scattering are likely to increase. Therefore, when the toner T is manufactured by a pulverization method, an effect that it is possible to prevent an increase in fogging and scattering of the toner T is more effectively achieved. Therefore, the above embodiment is more desirable.

=== Configuration of Image Forming System etc. ===
Next, an image forming system according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 20 is an explanatory diagram showing an external configuration of the image forming system. The image forming system 700 includes a computer 702, a display device 704, a printer 10, an input device 708, and a reading device 710.
In this embodiment, the computer 702 is housed in a mini-tower type housing, but is not limited thereto. The display device 704 is generally a CRT (Cathode Ray Tube), a plasma display, a liquid crystal display device, or the like, but is not limited thereto. As the printer 10, the printer described above is used. In this embodiment, the input device 708 uses a keyboard 708A and a mouse 708B, but is not limited thereto. In this embodiment, the reading device 710 uses a flexible disk drive device 710A and a CD-ROM drive device 710B. However, the reading device 710 is not limited to this. Disk) etc. may be used.

  FIG. 21 is a block diagram showing a configuration of the image forming system shown in FIG. An internal memory 802 such as a RAM and an external memory such as a hard disk drive unit 804 are further provided in a housing in which the computer 702 is housed.

  In the above description, an example in which the printer 10 is connected to the computer 702, the display device 704, the input device 708, and the reading device 710 to configure the image forming system has been described. However, the present invention is not limited to this. Absent. For example, the image forming system may include the computer 702 and the printer 10, and the image forming system may not include any of the display device 704, the input device 708, and the reading device 710.

  For example, the printer 10 may have a part of each function or mechanism of the computer 702, the display device 704, the input device 708, and the reading device 710. As an example, the printer 10 includes an image processing unit that performs image processing, a display unit that performs various displays, a recording medium attachment / detachment unit for attaching / detaching a recording medium that records image data captured by a digital camera or the like. It is good also as a structure to have.

  The image forming system realized in this way is a system superior to the conventional system as a whole system.

FIG. 2 is a diagram illustrating main components of a printer. It is a conceptual diagram of a developing device. It is sectional drawing which showed the main components of the developing device. FIG. 6 is a diagram showing a configuration around a regulating blade 560. FIG. 5A shows the HP position. FIG. 5B shows the connector attaching / detaching position. FIG. 5C shows the attachment / detachment position of the yellow developing device 54. FIG. 6A is a diagram related to the separation position, and FIG. 6B is a diagram related to the contact position. 2 is a block diagram showing a control unit 100. FIG. It is a figure showing a waveform of a development bias. 3 is a flowchart for explaining the operation of the printer. It is the schematic diagram which showed the change of Vmax and Vmin. It is the flowchart which showed the setting method of Vmax. It is the figure which showed the Vmax setting table. It is the flowchart which showed the setting method of Vmin. FIG. 6 is a schematic diagram showing a state in which a patch image is formed on an intermediate transfer body 70. FIG. 15A is a graph showing the relationship between the charge amount and the weight of the toner T adhering to the photoconductor 20 when only Vmax is changed. FIG. 15B is a graph showing the relationship between the charge amount and the number of toners T adhering to the photoconductor 20 when only Vmax is changed. FIG. 16A is a graph showing the relationship between the charge amount and the weight of the toner T adhering to the photoconductor 20 when only Vmin is changed. FIG. 16B is a graph showing the relationship between the charge amount and the number of toner T adhering to the photoconductor 20 when only Vmin is changed. FIG. 3 is a diagram illustrating a state where toner T adheres unevenly to a recording medium S. It is the graph which showed the relationship between the magnitude | size of Vmin when changing Vmax, and the density | concentration on a recording medium. 6 is a graph showing the relationship between the magnitude of Vmin and the density on a recording medium when the amount of toner T conveyed by the developing roller is changed. 1 is an explanatory diagram showing an external configuration of an image forming system. It is a block diagram which shows the structure of the image forming system shown in FIG.

Explanation of symbols

10 Printer, 10a Printer body, 20 Photoconductor, 30 Charging unit,
31 HP detector, 34 apparatus main body side connector, 40 exposure unit,
50 Developer holding unit, 50a, 50b, 50c, 50d Detachable part, 50e Rotating shaft,
51 Black developer, 52 Cyan developer, 53 Magenta developer,
54 Yellow developing unit, 51a, 52a, 53a, 54a Developer side memory,
51b, 52b, 53b, 54b Developer side connector, 60 Primary transfer unit,
70 intermediate transfer body, 75 cleaning unit, 76 cleaning blade,
80 secondary transfer unit, 90 fixing unit, 92 paper feed tray, 94 paper feed roller, 95 display unit, 96 registration roller, 100 control unit,
101 controller unit, 102 unit control unit, 112 interface,
113 Image memory, 114 Controller side memory, 114a EEPROM,
114b RAM, 116 unit control side memory, 116a EEPROM,
120 CPU, 121 serial interface (I / F), 122 main body side memory,
123 input / output port, 125 developing bias control circuit, 125a Vmax setting unit,
125b Vmin setting unit, 126 developing bias generator,
127a charging bias control circuit, 127b charging bias generator,
510 developing roller, 520 seal member, 524 seal biasing member,
530 toner container, 540 housing, 550 toner supply roller,
560 regulating blade, 560a rubber part, 560b rubber support part,
570 Blade backing member, 572 opening, 700 image forming system,
702 computer, 704 display device, 708 input device, 708A keyboard,
708B mouse, 710 reading device, 710A flexible disk drive device,
710B CD-ROM drive, 802 internal memory,
804 Hard disk drive unit, PS patch sensor, T toner

Claims (12)

An image carrier for carrying a latent image;
A developer carrying member for carrying the developer, carrying the developer to a position facing the image carrying member, and developing the latent image carried on the image carrying member by the developer carried to the position. When,
A transfer portion for transferring the developer image formed on the image carrier by development of the latent image to a medium and forming an image;
For developing the latent image, a first voltage for directing the developer from the developer carrier to the image carrier, and a developer for directing the developer from the image carrier to the developer carrier. A voltage application unit that alternately applies a second voltage to the developer carrier;
A first voltage setting unit for setting the first voltage based on transport amount information related to the transport amount of the developer by the developer carrier;
Maintaining the first voltage set by the first voltage setting unit and changing the second voltage to adjust the density of the image formed on the medium; and
An image forming apparatus comprising: The image forming apparatus according to claim 1,
A layer thickness regulating member for contacting the developer carrying member and regulating the layer thickness of the developer carried on the developer carrying member;
The image forming apparatus, wherein the transport amount of the developer is the transport amount after the layer thickness is regulated by the layer thickness regulating member. The image forming apparatus according to claim 2,
The layer thickness regulating member is
The tip of the layer thickness regulating member on the side in contact with the developer carrying member,
As seen from the contact position of the layer thickness regulating member that contacts the developer carrier, it faces the upstream side of the rotation direction of the developer carrier.
Provided,
The image forming apparatus, wherein the transport amount information is distance information related to a distance from the tip to the contact position. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus, wherein the transport amount information is surface roughness information relating to a surface roughness of the developer carrying member. The image forming apparatus according to any one of claims 1 to 4,
An image forming apparatus main body is detachable, includes the developer carrying member, and has a developing device for containing the developer carried on the developer carrying member,
The developing device is provided with a developing device storage unit that stores the transport amount information related to the transport amount of the developer stored in the developing device,
The image forming apparatus, wherein the first voltage setting unit sets the first voltage based on the transport amount information read from the developing device storage unit. An image forming apparatus according to any one of claims 1 to 5,
The transfer unit is provided with a transfer medium member that serves as a medium when transferring the developer image formed on the image carrier to the medium.
The transfer unit transfers the developer image formed on the image carrier to the transfer medium member, and transfers the developer image transferred to the transfer medium member to the medium to form an image. ,
A density detection member for detecting the density of a test pattern formed on the transfer medium member to adjust the density of an image formed on the medium;
The image forming apparatus, wherein the image density adjusting unit changes the second voltage based on a result of detecting the density of the test pattern by the density detecting member. The image forming apparatus according to claim 1, wherein:
The image forming apparatus, wherein the developer carrying member is made of metal. An image forming apparatus according to any one of claims 1 to 7,
The image forming apparatus, wherein the developer is manufactured by a pulverization method. The image forming apparatus according to claim 1, wherein:
Before the voltage application unit applies the first voltage and the second voltage to the developer carrier, the developer carried on the developer carrier is not in contact with the image carrier,
When the voltage application unit applies the first voltage to the developer carrier, the developer carried on the developer carrier flies toward the image carrier and adheres to the image carrier. And
When the voltage application unit applies the second voltage to the developer carrier, the developer attached to the image carrier flies toward the developer carrier and returns to the developer carrier. An image forming apparatus. An image carrier for carrying a latent image;
A developer carrying member for carrying the developer, carrying the developer to a position facing the image carrying member, and developing the latent image carried on the image carrying member by the developer carried to the position. When,
A transfer portion for transferring the developer image formed on the image carrier by development of the latent image to a medium and forming an image;
For developing the latent image, a first voltage for directing the developer from the developer carrier to the image carrier, and a developer for directing the developer from the image carrier to the developer carrier. A voltage application unit that alternately applies a second voltage to the developer carrier;
A first voltage setting unit for setting the first voltage based on transport amount information related to the transport amount of the developer by the developer carrier;
Maintaining the first voltage set by the first voltage setting unit and changing the second voltage to adjust the density of the image formed on the medium; and
Have
It has a layer thickness regulating member that contacts the developer carrying body and regulates the layer thickness of the developer carried on the developer carrying body, and the transport amount of the developer is controlled by the layer thickness regulating member. The transport amount after the layer thickness is regulated,
The layer thickness regulating member is
The tip of the layer thickness regulating member on the side in contact with the developer carrying member,
As seen from the contact position of the layer thickness regulating member that contacts the developer carrier, it faces the upstream side of the rotation direction of the developer carrier.
Provided,
The transport amount information is distance information related to a distance from the tip to the contact position,
The transport amount information is surface roughness information related to the surface roughness of the developer carrier.
An image forming apparatus main body is detachable, includes the developer carrying member, and has a developing device for containing the developer carried on the developer carrying member,
The developing device is provided with a developing device storage unit that stores the transport amount information related to the transport amount of the developer stored in the developing device,
The first voltage setting unit sets the first voltage based on the transport amount information read from the developing device storage unit,
The transfer unit is provided with a transfer medium member that serves as a medium when transferring the developer image formed on the image carrier to the medium.
The transfer unit transfers the developer image formed on the image carrier to the transfer medium member, and transfers the developer image transferred to the transfer medium member to the medium to form an image. ,
A density detection member for detecting the density of a test pattern formed on the transfer medium member to adjust the density of an image formed on the medium;
The image density adjustment unit changes the second voltage based on the detection result of the density of the test pattern by the density detection member,
The developer carrier is made of metal,
The developer is manufactured by a pulverization method,
Before the voltage application unit applies the first voltage and the second voltage to the developer carrier, the developer carried on the developer carrier is not in contact with the image carrier,
When the voltage application unit applies the first voltage to the developer carrier, the developer carried on the developer carrier flies toward the image carrier and adheres to the image carrier. And
When the voltage application unit applies the second voltage to the developer carrier, the developer attached to the image carrier flies toward the developer carrier and returns to the developer carrier. An image forming apparatus. A computer and an image forming apparatus connectable to the computer,
An image carrier for carrying a latent image;
A developer carrying member for carrying the developer, carrying the developer to a position facing the image carrying member, and developing the latent image carried on the image carrying member by the developer carried to the position. When,
A transfer portion for transferring the developer image formed on the image carrier by development of the latent image to a medium and forming an image;
For developing the latent image, a first voltage for directing the developer from the developer carrier to the image carrier, and a developer for directing the developer from the image carrier to the developer carrier. A voltage application unit that alternately applies a second voltage to the developer carrier;
A first voltage setting unit for setting the first voltage based on transport amount information related to the transport amount of the developer by the developer carrier;
Maintaining the first voltage set by the first voltage setting unit and changing the second voltage to adjust the density of the image formed on the medium; and
An image forming apparatus having
An image forming system comprising: Based on the transport amount information relating to the transport amount of the developer by the developer carrier that carries the developer, a first voltage for directing the developer from the developer carrier to the image carrier that carries the latent image is set. Steps to set,
In order to adjust the density of the image formed on the medium, the set first voltage is maintained, and the second voltage for directing the developer from the image carrier to the developer carrier is changed. Step to
Alternately applying the maintained first voltage and the changed second voltage to the developer carrier to develop the latent image;
Transferring a developer image formed on the image carrier by development of the latent image onto the medium to form an image;
An image forming method comprising:

Images