JP2007034204A - Image forming apparatus and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an image forming apparatus capable of properly restraining banding which occurs due to a long interval after the last development, and to realize an image forming system. <P>SOLUTION: The image forming apparatus includes: an image carrier for holding a latent image; a developing device with a rotatable developer carrier holding developer thereon, and used for developing the latent image on the image carrier from developer held on the developer carrier; and a controller which, in order to prevent nonuniform density when the latent image is developed by the developing device, carries out a rotating operation for the developer carrier as a preparation operation for the development such that as the length of time that the developing device is used increases, at least the rotating time or rotating speed of the developer carrier in the rotating operation is increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  Image forming apparatuses such as laser beam printers are already well known. Such an image forming apparatus includes, for example, an image carrier for carrying a latent image and a developer, and a rotatable developer for developing the latent image carried on the image carrier by the developer. And a carrier.

  Then, when an image signal or the like is transmitted from an external device such as a host computer, the image forming apparatus develops the latent image carried on the image carrier with the developer carried on the developer carrier. An image is formed, the developer image is transferred to a medium, and finally an image is formed on the medium.

By the way, after development by the developer carrier is not performed for a long time (that is, the developer carrier does not rotate for a long time), when the developer carrier develops a latent image, a developer image formed by the development is obtained. It is known that shading unevenness occurs, and this phenomenon is called neglected banding. Then, in order to prevent the occurrence of neglected banding, a method has been proposed in which the developer carrying member is rotated as a pre-development operation, and the charge amount of the developer is made uniform before the development. Yes.
JP 2004-126089 A

However, if the developing device is used for a long period of time, the occurrence of neglected banding tends to become remarkable. For this reason, when the developing device is used for a long period of time, even if the rotation operation of the developer carrier as a preparatory operation is executed, the occurrence of neglected banding may not be prevented.
SUMMARY An advantage of some aspects of the invention is that it realizes an image forming apparatus and an image forming system that can appropriately prevent the occurrence of neglected banding.

  In order to solve the above-mentioned problems, the main present invention includes an image carrier for carrying a latent image and a rotatable developer carrier for carrying a developer, and is carried on the developer carrier. A developing device that develops the latent image carried on the image carrier by the developed developer, and a pre-preparation operation of the development in order to prevent occurrence of density unevenness when the latent image is developed by the developing device. As a controller for executing the rotation operation of the developer carrier, as the usage period of the developing device becomes longer, at least one of the rotation time and the rotation speed of the developer carrier in the rotation operation is increased. And an image forming apparatus characterized by comprising:

  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 rotatable developer carrier for carrying a developer. The latent image carried on the image carrier by the developer carried on the developer carrier. A developing device that develops an image, and a controller that executes a rotation operation of the developer carrier as a pre-preparation operation of the development in order to prevent occurrence of density unevenness when the latent image is developed by the developing device And a controller for increasing at least one of a rotation time and a rotation speed of the developer carrying member in the rotating operation as a period of use of the developing device becomes longer. apparatus.
When the rotation time is increased, the charge amount of the developer carried on the developer carrying member is easily made uniform, so that it is possible to prevent the occurrence of neglected banding. Further, when the rotational speed is increased, for example, the developer carried on the developer carrying member is easily refreshed by a member or the like that contacts the developer carrying member, so that the occurrence of neglected banding can be prevented. For this reason, when at least one of the rotation time and the rotation speed of the developer carrying member in the rotation operation is increased as the developing device is used for a longer period, it is possible to appropriately prevent the occurrence of neglected banding. It becomes.

Further, in this image forming apparatus, the controller increases only the rotation speed of the rotation time and rotation speed of the developer carrying member in the rotation operation as the usage period of the developing device becomes longer. It is good as well.
In such a case, it is possible to appropriately prevent the occurrence of neglected banding with simple control.

  In the image forming apparatus, the controller may set the rotation time of the developer carrying member in the rotation operation to be constant regardless of a usage period of the developing device.

Further, in this image forming apparatus, the controller increases only the rotation time of the rotation time and the rotation speed of the developer carrying member in the rotation operation as the use period of the developing device becomes longer. It is good as well.
In such a case, it is possible to appropriately prevent the occurrence of neglected banding with simple control.

  In the image forming apparatus, the controller may be configured to increase at least one of a rotation time and a rotation speed of the developer carrier in the rotation operation as the accumulated rotation time of the rotation of the developer carrier increases. May be increased.

In the image forming apparatus, the latent image may not be carried on the image carrier during the preliminary preparation operation.
In such a case, since the development is not performed during the preliminary preparation operation, it is possible to suppress the consumption of the developer.

In addition, in the image forming apparatus, the developing device includes a scraping member that rotates while being in contact with the developer carrier and scrapes off the developer on the developer carrier. It is good as well.
In such a case, the unevenness of the charge amount of the developer is more appropriately eliminated by the action of the scraping member.

(A) an image carrier for carrying a latent image; and (b) a rotatable developer carrier for carrying a developer, and the developer carried on the developer carrier by the developer. A developing device that develops the latent image carried on the image carrier, and (c) the pre-preparation operation of the development in order to prevent the occurrence of uneven density when developing the latent image by the developing device. A controller for executing a rotation operation of the developer carrier, wherein the controller increases at least one of a rotation time and a rotation speed of the developer carrier in the rotation operation as a usage period of the developing device becomes longer. (D), and (e) the rotation speed of the rotation time and rotation speed of the developer carrier in the rotation operation as the use period of the developing device becomes longer. (F) the controller makes the rotation time of the developer carrier in the rotation operation constant regardless of the period of use of the developing device, and (g) the controller As the accumulated rotation time of the rotation becomes longer, at least one of the rotation time and the rotation speed of the developer carrier in the rotation operation is increased, and (h) during the preliminary preparation operation, The latent image is not carried, and (i) the developing device includes a scraping member that rotates in contact with the developer carrier and scrapes off the developer on the developer carrier. An image forming apparatus.
According to such an image forming apparatus, the effect of appropriately preventing the occurrence of neglected banding is most effectively achieved.

Also, (A) a computer and (B) an image forming apparatus connected to the computer, an image carrier for carrying a latent image, and a rotatable developer carrying for carrying the developer And a developing device that develops the latent image carried on the image carrier by the developer carried on the developer carrier, and density unevenness occurs when the latent image is developed by the developing device. In order to prevent this, the controller carries out the rotation operation of the developer carrier as a pre-preparation operation of the development, and as the usage period of the developing device becomes longer, the developer carrier in the rotation operation An image forming system comprising: (C) an image forming apparatus having a controller that increases at least one of a rotation time and a rotation speed.
According to such an image forming system, it is possible to appropriately prevent the occurrence of neglected banding.

=== Overview of Image Forming Apparatus ===
An outline of a laser beam printer (hereinafter also referred to as “printer”) 10 as an example of the image forming apparatus will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram illustrating main components constituting the printer 10. FIG. 2 is a block diagram showing the control unit 100 of 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.

<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 member 70, a cleaning blade 76; a secondary transfer unit 80; a fixing unit 90; The control unit 100 is an example of a controller that controls the unit and the like and controls the operation as a printer.

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

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

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

  The developing device holding unit 50 can move the positions of the four developing devices 51, 52, 53, and 54 by rotating with the four developing devices 51, 52, 53, and 54 being mounted. It is said. 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, and the four developing devices 51, 52, and 53 are provided. , 54 are rotatable about the rotation axis 50e while maintaining their relative positions. Each time image formation for one page is completed, it is selectively opposed to the photoconductor 20, and is formed on the photoconductor 20 with toner accommodated in each of the developing devices 51, 52, 53, and 54. The latent images are developed sequentially. Each of the four developing devices 51, 52, 53, 54 described above can be attached to and detached from the printer main body 10 a, specifically, the attaching / detaching portion of the developing device holding unit 50. Details of the developing device will be described later.

The primary transfer unit 60 is a device for transferring a single color toner image formed on the photoconductor 20 to the intermediate transfer body 70. When four color toners are sequentially transferred in a superimposed manner, the full color toner is transferred to the intermediate transfer body 70. An image is formed. 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.
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 such as paper, film, or cloth. The fixing unit 90 is a device for fusing a single color toner image or a full color toner image transferred onto a recording medium onto a recording medium such as paper to form a permanent image.

The cleaning blade 76 is made of rubber and is in contact with the surface of the photoreceptor 20. The cleaning blade 76 scrapes and removes the toner remaining on the photoconductor 20 after the toner image is transferred onto the intermediate transfer body 70 by the primary transfer unit 60.
The photoconductor unit 75 is provided between the primary transfer unit 60 and the exposure unit 40, and stores the photoconductor 20, the charging unit 30, the cleaning blade 76, and the toner scraped off by the cleaning blade 76 (not shown). A waste toner container is provided.

  As shown in FIG. 2, the control unit 100 includes a main controller 101 and a unit controller 102. An image signal is input to the main controller 101, and the unit controller 102 responds to an instruction based on the image signal. The unit is controlled to form an image.

<Operation of Printer 10>
Next, the operation of the printer 10 configured as described above will be described with reference to other components.
First, when an image signal from a host computer (not shown) is input to the main controller 101 of the printer 10 via the interface (I / F) 112, the photosensitive unit is controlled by the unit controller 102 based on a command from the main controller 101. The developing roller 510 and the intermediate transfer body 70 provided on the body 20, the developing devices 51, 52, 53, and 54 rotate. The photoconductor 20 is sequentially charged by the charging unit 30 at the charging position while rotating.

The charged area of the photoconductor 20 reaches an exposure position as the photoconductor 20 rotates, and a latent image corresponding to image information of the first color, for example, yellow Y, is formed in the area by the exposure unit 40. . 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.
The latent image formed on the photoconductor 20 reaches the development position as the photoconductor 20 rotates, and is developed with yellow toner by the yellow developing device 54. As a result, a yellow toner image is formed on the photoreceptor 20.
The yellow toner image formed on the photoconductor 20 reaches the primary transfer position as the photoconductor 20 rotates, and is transferred to the intermediate transfer body 70 by the primary transfer unit 60. At this time, a primary transfer voltage having a polarity opposite to the charging polarity of the toner 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 for the second color, the third color, and the fourth color, the four color toner images corresponding to the respective image signals are transferred onto the intermediate transfer body 70 in an overlapping manner. . 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. 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 elapsed, the toner adhering to the surface of the photoconductor 20 is scraped off by the cleaning blade 76 to prepare for charging for forming the next latent image. The toner scraped off is collected in a waste toner container.

=== Overview of Control Unit ===
Next, the configuration of the control unit 100 will be described with reference to FIG. The control unit 100 has a main controller 101 and a unit controller 102.
The main controller 101 includes a CPU 111, an interface 112 for connecting to a computer (not shown), an image memory 113 for storing an image signal input from the computer, an electrically rewritable EEPROM 114a, a RAM 114b, and various controls. And a main controller side memory 114 composed of a program ROM or the like having a program for the above.

  The CPU 111 of the main controller 101 controls the reading and reading of the image data input through the interface to the image memory 113 and synchronizes with the CPU 120 of the unit controller 102 based on the control signal input from the computer. I am in charge of control.

  The unit controller 102 includes a CPU 120, an electrically rewritable EEPROM 116a, RAM, a unit controller side memory 116 including a program ROM having various control programs, and each unit (charging unit 30, exposure unit) of the apparatus main body. 40, a developing device holding unit 50, a primary transfer unit 60, a photosensitive unit 75, a secondary transfer unit 80, a fixing unit 90, and a display unit 95).

  The CPU 120 of the unit controller 102 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 main controller 101. That is, each unit is controlled based on a signal input from the main controller 101 while detecting a state of each unit by receiving a signal from a sensor or the like included in each unit.

  The CPU 120 included in the unit controller 102 is connected to a non-volatile storage element (hereinafter, also referred to as “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 wirelessly communicates with the elements 51a, 52a, 53a, 54a provided in the developing devices 51, 52, 53, 54 via the serial interface 121, the transmission / reception circuit 123, and the main body antenna 124. Communication is possible.

  When the developing device is attached to the detachable portion, the CPU 120 reads the developing device information stored in the element by wireless communication with the element provided in the developing device. Here, the developing device information is information such as the color of the toner stored in the developing device, the cumulative consumption amount of the toner, the cumulative rotation time during which the developing roller 510 has rotated. The read developer information is stored in a predetermined area of the main body side memory 122 in association with each developer.

  Further, the CPU 120 updates the developing device information stored in the main body side memory 122 for each developing device. That is, the CPU 120 updates the accumulated consumption amount and the accumulated rotation time when the developing roller 510 of each developing device is rotated or toner is consumed after reading the developing device information from the element. .

  Further, when the developing device is removed from the attaching / detaching unit, the CPU 120 displays the developing device information (the accumulated rotation time of the developing roller 510 and the cumulative consumption amount of toner) stored in the main body side memory 122. Write to the element provided in the developer.

=== Overview of Developer ===
Next, the configuration and operation of the developing devices 51, 52, 53, and 54 will be described with reference to FIGS. FIG. 3 is a perspective view of the yellow developing device 54. FIG. 4 is a cross-sectional view showing the main components of the yellow developing device 54. Note that the cross-sectional view shown in FIG. 4 represents a cross-section obtained by cutting the yellow developing device 54 along a plane perpendicular to the longitudinal direction shown in FIG. 4, the vertical direction is indicated by arrows as in FIG. 1. For example, the central axis of the developing roller 510 is lower than the central axis of the photoconductor 20. In FIG. 4, the yellow developing device 54 is shown in a state where the yellow developing device 54 is located at a developing position facing the photoconductor 20.

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

<Configuration of Yellow Developer 54>
First, the configuration of the yellow developing device 54 will be described. The yellow developing device 54 includes a developing roller 510 that is an example of a developer carrier, a toner container 530, a housing 540, a toner supply roller 550 that is an example of a scraping member, a regulating blade 560, and a seal member 520. .

  The developing roller 510 carries the toner T and transports it to a facing position facing the photoreceptor 20, and develops the latent image carried on the photoreceptor 20 by the toner T transported to the facing position. The developing roller 510 is made of metal and is made of an aluminum alloy such as 5056 aluminum alloy or 6063 aluminum alloy, or an iron alloy such as STKM, and is subjected to nickel plating, chrome plating, or the like as necessary. Yes.

  Further, as shown in FIG. 4, the developing roller 510 can rotate around the central axis. As shown in FIG. 4, the developing roller 510 rotates in a direction (counterclockwise in FIG. 4) opposite to the rotation direction of the photoconductor 20 (clockwise in FIG. 4). The central axis is below the central axis of the photoconductor 20.

  As shown in FIG. 4, there is a gap between the developing roller 510 and the photoconductor 20 in a state where the yellow developing device 54 faces the photoconductor 20. That is, the yellow developing device 54 develops the latent image formed on the photoconductor 20 in a non-contact state. When developing the latent image formed on the photoconductor 20, a developing bias in which a DC voltage and an AC voltage are superimposed is applied to the developing roller 510, and alternating between the developing roller 510 and the photoconductor 20. An electric field is formed.

  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 facing position into the developing device without being scraped off. The seal member 520 is a seal made of a polyethylene film or the like. The seal member 520 is supported by a seal support sheet metal 522 and is attached to the housing 540 via the seal support sheet metal 522. Further, a seal urging member 524 made of malt plain or the like is provided on the opposite side of the seal member 520 from the developing roller 510 side. The seal member 520 is developed by the elastic force of the seal urging member 524. 510 is pressed. Note that the contact position where the seal member 520 contacts the developing roller 510 is above the central axis of the developing roller 510.

  The housing 540 is manufactured by welding a plurality of integrally molded housing parts, that is, an upper housing part 542 and a lower housing part 544, and the inside thereof is inward from the inner wall (FIG. 4). A partition wall 545 for partitioning the protruded toner T is divided into two toner storage portions 530, that is, a first toner storage portion 530a and a second toner storage portion 530b. The housing 540 has a housing opening 572 at the lower portion, and the developing roller 510 is disposed in the housing opening 572 with a part thereof exposed. An element 54 a is attached to the housing 540.

  Further, an agitating member for agitating the toner T may be provided in the toner accommodating portion 530. In the present embodiment, each developing device (the black developing device 51, the magenta developing device) is rotated with the rotation of the developing device holding unit 50. The toner 52, the cyan developing device 53, and the yellow developing device 54) rotate, whereby the toner T in each developing device is agitated. Therefore, the toner accommodating portion 530 is not provided with an agitating member.

  The toner supply roller 550 is provided in the first toner storage portion 530 a described above, and has a function of supplying the toner T stored in the first toner storage portion 530 a to the developing roller 510. Further, the toner supply roller 550 has a function of rotating while being in contact with the developing roller 510 and scraping off the toner T remaining on the developing roller 510 after development from the developing roller 510. The toner supply roller 550 is made of polyurethane foam or the like, and is in contact with the developing roller 510 in an elastically deformed state. The toner supply roller 550 is disposed below the 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 in a direction (clockwise in FIG. 4) opposite to the rotation direction of the developing roller 510 (counterclockwise in FIG. 4). The central axis is below the rotational central axis of the developing roller 510.

  The regulating blade 560 applies a charge to the toner T carried on the developing roller 510 and 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 portion 560a is supported by the rubber support portion 560b, and the rubber support portion 560b is attached to the housing 540 via the blade support metal plate 562 with one end thereof supported by the blade support metal plate 562. . 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.

  Here, the rubber portion 560 a is pressed against the developing roller 510 by the elastic force caused by the bending of the rubber support portion 560 b. Further, the blade back member 570 prevents the toner T from entering between the rubber support portion 560b and the housing 540, stabilizes the elastic force due to the bending of the rubber support portion 560b, and provides rubber from the back of the rubber portion 560a. The rubber portion 560 a is pressed against the developing roller 510 by urging the portion 560 a toward the developing roller 510. Therefore, the blade back member 570 improves the uniform contact property of the rubber portion 560a to the developing roller 510.

  The end of the regulating blade 560 opposite to the side supported by the blade support metal plate 562, that is, the tip is not in contact with the developing roller 510, and a portion away from the tip by a predetermined distance is the developing roller. 510 is in contact with a width. That is, the regulating blade 560 is not in contact with the developing roller 510 at the edge, but is in contact with the belly. The regulating blade 560 is disposed so that the tip thereof faces the upstream side in the rotation direction of the developing roller 510, and is in a so-called counter contact. The contact position where the regulating blade 560 contacts the developing roller 510 is below the central axis of the developing roller 510 and below the central axis of the toner supply roller 550.

<Operation of Yellow Developer 54>
Next, the operation of the yellow developing device 54 will be described. In the yellow developing device 54 configured as described above, the toner supply roller 550 rotates to supply 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 contact position of the regulating blade 560 as the developing roller 510 rotates, and the layer thickness is regulated and electric charge is applied when passing through the contact position. Is done. The toner T on the developing roller 510 to which the layer thickness is regulated and the charge is applied reaches a facing position facing the photoreceptor 20 by further rotation of the developing roller 510, and the photoreceptor is subjected to an alternating electric field at the facing position. The latent image formed on 20 is subjected to development.
The toner T on the developing roller 510 that has passed through the opposite position by the further rotation of the developing roller 510 passes through the upper seal member 520 and is collected in the developing device without being scraped off by the upper seal member 520. Further, the toner T still remaining on the developing roller 510 can be scraped off by the toner supply roller 550.

=== Developing position, communication position, and attaching / detaching position of the developing device ===
As described above, the developing devices 51, 52, 53, and 54 move with the movement of the attaching / detaching portions 50a, 50b, 50c, and 50d. At this time, the attachment / detachment unit moves so that each developing device is positioned at a predetermined position. As the predetermined position, there are a developing position, a communication position, and an attaching / detaching position. Since the developing position, the communication position, and the attachment / detachment position of each developing device are the same, the development position, the communication position, and the attachment / detachment position of the yellow developing device 54 will be described below with reference to FIGS. 5A to 5D. To do. FIG. 5A is a diagram showing a state in which the yellow developing device 54 is located at the development position. FIG. 5B is a diagram showing a state where the yellow developing device 54 is located at the communication position. FIG. 5C is a diagram showing a state in which the yellow developing device 54 is located at the attachment / detachment position. FIG. 5D is a diagram showing a state where the developing device holding unit 50 is located at the home position.

  In the state shown in FIG. 5A, the yellow developing device 54 is located at the developing position where the developing roller 510 faces the photoconductor 20. In this state, the developing roller 510 can develop the latent image carried on the photoconductor 20. In the state where the yellow developing device 54 is located at the developing position, the magenta developing device 52 is located at the communication position.

  Further, from the state shown in FIG. 5A, when the developing device holding unit 50 rotates around the rotation shaft 50e by a predetermined angle in the Z direction shown in FIG. 5A, the state shown in FIG. 5B is obtained. In the state shown in FIG. 5B, the yellow developing device 54 is located at the communication position. In this state, the element 54a provided in the yellow developing device 54 faces the main body antenna 124 in a non-contact state. The element 54a can communicate with the main body antenna 124. In the state where the yellow developing device 54 is located at the communication position, the black developing device 51 is located at the developing position. Therefore, element communication with the main body side antenna 124 can be performed when the black developing device 51 develops the latent image carried on the photoconductor 20.

  Further, from the state shown in FIG. 5B, when the developing device holding unit 50 rotates around the rotation shaft 50e by a predetermined angle in the Z direction shown in FIG. 5B, the state shown in FIG. 5C is obtained. In the state shown in FIG. 5C, the yellow developing device 54 is located at the attachment / detachment position. In this state, the yellow developing device 54 can be attached / detached via the developing device attaching / detaching opening 10e, that is, can be attached to or detached from the attaching / detaching portion 50d.

  It should be noted that after the power is turned on (power is supplied) to the printer 10 and the initialization operation is performed or before the printer 10 forms an image, the developing device holding unit 50 is in the home position shown in FIG. 5D. Is located.

=== About neglected banding ===
When the developing unit develops the latent image on the photoconductor 20 after the development by the developing roller 510 is not performed for a long time (that is, the developing roller 510 does not rotate for a long time), the toner image formed by the development has uneven density ( So-called neglected banding occurs. The mechanism of this neglected banding will be described below.

  The neglected banding is considered to occur mainly because the state of the small particle size toner (fine toner) adhering to the surface of the developing roller 510 differs in the circumferential direction of the developing roller 510.

  The developing device according to the present embodiment will be described as an example. Fine powder toner adhering to the surface of the developing roller 510 is contained in the toner storage portion 530 (in FIG. 4, the contact portion of the seal member 520 with the developing roller 510). And the right side when the two abutting portions are used as the boundary in FIG. 4. Depending on whether it is located in (part), the exposed environment varies greatly. For example, since the fine toner in the toner storage unit 530 has a large amount of toner in the vicinity thereof, the fine powder toner outside the toner storage unit 530 receives less pressure because the toner receives pressure from the toner. . Further, since the inside of the toner storage portion 530 is a sealed space, but the outside of the toner storage portion 530 is an open space, the ambient temperature and humidity of the fine powder toner in the toner storage portion 530 and the outside of the toner storage portion 530 The ambient temperature and ambient humidity of the fine toner are greatly different from each other. When the developing roller 510 does not rotate (does not move) for a long time, the environment affects the state of the fine toner, and the state of the fine toner is changed inside and outside the toner container 530 due to the above-described difference in the environment. It will be very different.

  The difference in the state of the fine toner causes a problem of non-uniformity of the toner charge amount in the circumferential direction of the developing roller 510 (inside and outside of the toner container 530) when the developing device develops the latent image. Eventually, the non-uniformity of the charge amount results in non-uniformity of toner flying from the developing device to the photoconductor 20, and the toner image (finally the image) obtained by development is unevenly shaded (so-called neglected). Banding) will occur.

  The printer 10 (specifically, the control unit 100) according to the present embodiment uses the developing roller 510 as a pre-development operation for developing in order to prevent the occurrence of neglected banding when developing the latent image by the developing roller 510. Rotate (this rotating operation is also called a preparatory rotating operation). Accordingly, the preparation rotation operation of the developing roller 510 in the printer 10 according to the present embodiment will be described below.

=== Preparatory Rotation Operation of Developing Roller 510 after Power-On ===
In a state where the printer 10 is not powered on, the developing roller 510 does not rotate. For this reason, if the printer 10 is not powered on for a long period of time, the developing roller 510 will not rotate for a long time. When the developing roller 510 does not rotate for a long time and then the printer 10 is turned on and development is performed, neglected banding is likely to occur. Therefore, in the printer 10 according to the present embodiment, the preparatory rotation operation of the developing roller 510 is executed when the printer 10 is turned on (that is, supplied with power).

  A preparatory rotation operation of the developing roller 510 after the power is turned on will be described with reference to FIGS. FIG. 6 is a flowchart for explaining the preparatory rotation operation of the developing roller 510 after the power supply to the printer 10 is turned on. FIG. 7 is a table showing a correspondence relationship between the accumulated rotation time of the developing roller 510 and the rotation speed of the developing roller 510 in the preparation rotation operation. FIG. 8 is a flowchart for explaining the preparatory rotation operation of the developing roller 510 of each developing device.

  Note that various operations of the printer 10 when the preparation rotation operation is executed are mainly realized by the control unit 100 (FIG. 2). In particular, in the present embodiment, it is realized by the CPU processing a program stored in the ROM. And this program is comprised from the code | cord | chord for performing the various operation | movement demonstrated below.

  When the printer 10 is powered on (s102), the control unit 100 first determines the rotation speed of the developing roller 510 in the preparation rotation operation (s104). The control unit 100 refers to the table shown in FIG. 7 stored in the unit controller side memory 116 and the like, and the developing roller 510 in the preparation rotation operation according to the usage period of each developing device 51, 52, 53, 54. Determine the rotation speed. For example, if the cumulative rotation time of the developing roller 510 of the yellow developing device 54 is 3000 (s), the control unit 100 determines the rotation speed of the developing roller 510 in the preparation rotation operation as 1.0 V (mm / s). . Here, V is the rotational speed of the developing roller 510 during image formation.

  Further, as shown in FIG. 7, the rotation speed determined by the control unit 100 increases as the cumulative rotation time of the developing roller 510 (this cumulative rotation time is an index indicating the usage period of the developing device) becomes longer. ,growing. For this reason, the control unit 100 increases the rotation speed of the developing roller 510 in the preparatory rotation operation as the use period of the developing roller 510 becomes longer.

  On the other hand, the control unit 100 makes the rotation time of the developing roller 510 constant in the preparation rotation operation regardless of the usage period of the developing devices 51, 52, 53, and 54. That is, the control unit 100 rotates the developing roller 510 for a predetermined time (in this embodiment, 2 (s)) during the preparatory rotation operation.

As described above, the control unit 100 according to the present embodiment increases only the rotation speed of the rotation time and the rotation speed of the developing roller 510 in the preparation rotation operation as the developing device usage period becomes longer.
Next, the control unit 100 causes the developing roller 510 of each developing device to perform a preparatory rotating operation at the rotational speed determined in s102 (s106).

  Here, the preparatory rotation operation of the developing roller 510 of each developing device will be described in detail. When the printer 10 is powered on, the developing device holding unit 50 is positioned at the home position shown in FIG. 5D. Since the preparatory rotation operation is performed when the developing device is located at the developing position, the control unit 100 needs to rotate the developing device holding unit 50 located at the home position. Therefore, the control unit 100 rotates the developing device holding unit 50 so that the developing device for the first color (here, the developing device for the first color is the yellow developing device 54) is shown in FIG. 5A. (S202).

  Next, the control unit 100 executes a preparatory rotation operation of the developing roller 510 of the yellow developing device 54 located at the developing position (s204). That is, the control unit 100 rotates the developing roller 510 of the yellow developing device 54 for a certain period of time at the rotational speed determined in step s104.

  Next, the control unit 100 rotates the developing device holding unit 50 to position the second color developing device (here, the second color developing device is the black developing device 51) at the developing position. (S206), the preparatory rotation operation of the developing roller 510 of the black developing device 51 is executed (s208). That is, the control unit 100 rotates the developing roller 510 for a predetermined time at the rotation speed determined in step s104.

  Next, the control unit 100 rotates the developing device holding unit 50 to position the third color developing device (here, the third color developing device is the cyan developing device 53) at the developing position. (S210), the preparatory rotation operation of the developing roller 510 of the cyan developing device 53 is executed (s212). That is, the control unit 100 rotates the developing roller 510 for a predetermined time at the rotation speed determined in step s104.

Next, the control unit 100 rotates the developing device holding unit 50 so that the fourth color developing device (here, the fourth color developing device is the magenta developing device 52) is positioned at the developing position. (S214), the preparatory rotation operation of the developing roller 510 of the magenta developing device 52 is executed (s216). That is, the control unit 100 rotates the developing roller 510 for a predetermined time at the rotation speed determined in s104.
When the preparatory rotation operation of the developing roller 510 of each developing unit is completed, the control unit 100 rotates the developing unit holding unit 50 to position the developing unit holding unit 50 at the home position.

  Note that during the preparatory rotation operation of the developing roller 510 of each developing device, no latent image is carried on the photosensitive member 20 and no developing bias is applied to the developing roller 510. For this reason, the toner carried on the developing roller 510 does not go to the photoconductor 20.

<Effect of performing the above-described preparatory rotation operation>
As described above, the printer 10 according to the present embodiment includes the control unit 100 that increases the rotation speed of the developing roller 510 in the preparation rotation operation as the usage period of the developing devices 51, 52, 53, and 54 becomes longer. ing. As a result, it is possible to appropriately prevent the occurrence of neglected banding. This will be described in detail below.

As described above, in the printer 10, the preparatory rotation operation of the developing roller 510 is performed in order to prevent the occurrence of neglected banding. Conventionally, for example, a preparation rotation operation in which the rotation speed and the rotation time of the developing roller 510 are constant is executed regardless of the period of use of the developing device.
However, if the developing unit 51, 52, 53, 54 is used for a long period of time, the amount of fine toner adhering to the surface of the developing roller 510 increases. Therefore, if the developing unit is used for a long period of time, the occurrence of neglected banding becomes significant. Cheap. For this reason, if the developing device is used for a long period of time, even if the conventional preparatory rotation operation is performed, the finely powdered toner on the developing roller 510 is not properly removed, which may prevent the occurrence of neglected banding.

Therefore, in this embodiment, the rotation speed of the developing roller 510 in the preparatory rotation operation is increased as the usage period of the developing devices 51, 52, 53, and 54 becomes longer.
When the rotation speed of the developing roller 510 is increased, the toner carried on the developing roller 510 is easily refreshed by the toner supply roller 550 that is in contact with the developing roller 510. For this reason, when the rotation speed of the developing roller 510 in the preparatory rotation operation is increased as the developing device usage period becomes longer, the left banding adhered to the surface of the developing roller 510 when the developing device usage period becomes longer. The fine toner, which is the main cause of the occurrence of toner, is appropriately removed. Since the toner charge amount is easily made uniform by removing the fine toner, it is possible to appropriately prevent the occurrence of neglected banding.

=== Regarding Modified Example of Preparation Rotation Operation ===
In the above-described preparatory rotation operation, the control unit 100 increases only the rotation speed of the rotation time and the rotation speed of the developing roller 510 in the preparatory rotation operation as the developer usage period becomes longer. However, the present invention is not limited to this. For example, the control unit 100 may increase only the rotation time of the rotation time and the rotation speed of the developing roller 510 in the preparation rotation operation as the use period of the developing devices 51, 52, 53, and 54 becomes longer. .

  FIG. 9 is a table showing a correspondence relationship between the accumulated rotation time of the developing roller 510 and the rotation time of the developing roller 510 in the preparation rotation operation. As shown in FIG. 9, as the cumulative rotation time of the developing roller 510 becomes longer, the rotation time of the developing roller 510 during the preparation rotation operation becomes longer. That is, the control unit 100 increases the rotation time of the developing roller 510 in the preparation rotation operation as the cumulative rotation time of the developing roller 510 becomes longer.

  The control unit 100 refers to the table shown in FIG. 9 stored in the unit controller side memory 116 or the like, and develops the developing roller 510 in the preparatory rotation operation according to the usage period of each developing device 51, 52, 53, 54. Determine the rotation time. For example, when the accumulated rotation time of the developing roller 510 is 4000 (s), the rotation time in the preparation rotation operation of the developing roller 510 is determined to be 2 (s). Note that the control unit 100 keeps the rotation speed of the developing roller 510 constant (for example, 1.0 V) regardless of the usage period of the developing device from the viewpoint of simplifying the control.

  When the rotation time of the developing roller 510 in the preparation rotating operation is increased, the charge amount of the toner carried on the developing roller 510 is easily made uniform. Therefore, as described above, when the rotation time of the developing roller 510 in the preparatory rotation operation is increased as the developing device usage period becomes longer, the occurrence of neglected banding is prevented even if the developing device usage period becomes longer. It becomes possible to do.

  Further, the control unit 100 may increase both the rotation time and the rotation speed of the developing roller 510 in the preparation rotation operation as the use period of the developing devices 51, 52, 53, and 54 becomes longer. For example, when the cumulative rotation time of the developing roller 510 is 4000 (s), the control unit 100 sets the rotation time of the developing roller 510 in the preparation rotation operation to 2 (s) and sets the rotation speed to 1.0 V. (Mm / s), and when the cumulative rotation time of the developing roller 510 is 6000 (s), the rotation time of the developing roller 510 in the preparatory rotation operation is 3 (s), and the rotation speed is 1. It may be set to 2V. According to such control, it is possible to effectively prevent the occurrence of neglected banding even if the developing device is used for a long period of time.

  From the above, when the control unit 100 increases at least one of the rotation time and the rotation speed of the developing roller 510 in the preparation rotation operation as the usage period of the developing devices 51, 52, 53, and 54 becomes longer, It is possible to prevent the occurrence of neglected banding.

=== 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.

  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 embodiment, the developing roller 510 is used as the developer carrying member, and the toner supply roller 550 is used as the scraping member. However, the present invention is not limited to this example. The take-up member may be a belt-like member.

In the above embodiment, the preparatory rotation operation of the developing roller 510 when the printer 10 is turned on has been described as the preparatory rotation operation of the developing roller 510. However, the present invention is not limited to this.
For example, when the developing device is mounted on the printer main body 10a, the preparatory rotation operation of the developing roller 510 of the developing device may be executed. Further, when the time when the developing roller 510 is not continuously rotated while the printer 10 is turned on exceeds a predetermined time, the preparatory rotation operation of the developing roller 510 may be executed. .

Further, in the above embodiment, the control unit 100 sets the rotation speed of the developing roller 510 in the preparation rotation operation to be constant regardless of the usage period of the developing devices 51, 52, 53, and 54. It is not limited.
For example, the control unit 100 may reduce the rotation time of the developing roller 510 in the preparatory rotation operation as the developing device usage period becomes longer.

Further, in the above embodiment, the cumulative rotation time during which the developing roller 510 is rotated is used as an index indicating the usage period of the developing devices 51, 52, 53, and 54. Then, the control unit 100 increases at least one of the rotation time and the rotation speed of the developing roller 510 in the preparation rotation operation as the accumulated rotation time becomes longer. However, it is not limited to the above.
For example, the cumulative consumption of toner stored in the developing device is used as an index indicating the usage period of the developing devices 51, 52, 53, and 54, and the control unit 100 rotates the preparation rotation as the cumulative consumption of toner increases. At least one of the rotation time and the rotation time of the developing roller 510 in the operation may be increased.

Furthermore, in the above-described embodiment, the latent image is not carried on the photoconductor 20 during the preliminary preparation operation. However, the present invention is not limited to this. For example, the latent image may be carried on the photoconductor 20 during the preliminary preparation operation.
However, if no latent image is carried on the photoconductor 20 during the preparatory operation, the development is not executed, so that it is possible to save toner consumption. Therefore, the above embodiment is more desirable.

Furthermore, in the above embodiment, as shown in FIG. 4, the printer 10 has a toner supply roller 550 that rotates while being in contact with the developing roller 510 and scrapes off the toner on the developing roller 510. However, the present invention is not limited to this. For example, the printer 10 may not include the toner supply roller 550.
However, when the printer 10 includes the toner supply roller 550, the toner supply roller 550 can solve the above-described non-uniformity of the toner charge amount more appropriately. 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. 10 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, but is not limited to this. For example, an MO (Magneto Optical) disk drive device or a DVD (Digital Versatile) is used. Disk) etc. may be used.

  FIG. 11 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 constituting the printer. 2 is a block diagram showing a control unit 100 of the printer 10. FIG. 2 is a perspective view of a yellow developing device 54. FIG. 3 is a cross-sectional view showing main components of a yellow developing device 54. FIG. FIG. 5A is a diagram showing a state in which the yellow developing device 54 is located at the development position. FIG. 5B is a diagram showing a state where the yellow developing device 54 is located at the communication position. FIG. 5C is a diagram showing a state in which the yellow developing device 54 is located at the attachment / detachment position. FIG. 5D is a view showing a state where the developing device holding unit 50 is located at the home position. 6 is a flowchart for explaining a preparatory rotation operation of the developing roller 510 after the power supply to the printer 10 is turned on. 6 is a table showing a correspondence relationship between a cumulative rotation time of the developing roller 510 and a rotation speed of the developing roller 510 in a preparation rotation operation. It is a flowchart for demonstrating the preparatory rotation operation | movement of the developing roller of each developing device. 6 is a table showing a correspondence relationship between an accumulated rotation time of the developing roller 510 and a rotation time of the developing roller 510 in a preparation rotation operation. 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, 10e Developing device attachment / detachment opening,
20 photoconductor, 30 charging unit, 40 exposure unit,
50 Developer holding unit, 50a, 50b, 50c, 50d Detachable part,
50e Rotating shaft, 51 Black developer, 52 Magenta developer,
53 Cyan developer, 54 Yellow developer,
51a, 52a, 53a, 54a element, 60 primary transfer unit,
70 intermediate transfer member, 75 photosensitive member 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 main controller,
102 unit controller, 111 CPU, 112 interface,
113 Image memory, 114 Main controller side memory,
114a EEPROM, 114b RAM,
116 Unit controller side memory, 116a EEPROM,
120 CPU, 121 serial interface, 122 body side memory,
123 transceiver circuit, 124 body antenna,
510 developing roller, 520 seal member, 522 seal support sheet metal,
524 seal urging member, 530 toner accommodating portion, 530a first toner accommodating portion,
530b second toner storage portion, 540 housing, 542 upper housing portion,
544 lower housing portion, 550 toner supply roller, 560 regulating blade,
560a rubber part, 560b rubber support part, 562 blade support sheet metal,
570 Blade backing member, 572 Housing opening,
700 image forming system, 702 computer, 704 display device,

708 input device, 708A keyboard, 708B mouse, 710 reader,
710A flexible disk drive device,
710B CD-ROM drive device,
802 Internal memory, 804 hard disk drive unit, T toner

Claims (9)

An image carrier for carrying a latent image;
A developing device comprising a rotatable developer carrier for carrying the developer, and developing the latent image carried on the image carrier by the developer carried on the developer carrier;
A controller that executes a rotation operation of the developer carrying member as a pre-preparation operation of the development in order to prevent occurrence of density unevenness during development of the latent image by the developing device; A controller that increases at least one of a rotation time and a rotation speed of the developer carrying member in the rotation operation as a use period becomes longer;
An image forming apparatus comprising: The image forming apparatus according to claim 1,
The image forming apparatus, wherein the controller increases only the rotation speed of the rotation time and rotation speed of the developer carrying member in the rotation operation as the use period of the developing device becomes longer. The image forming apparatus according to claim 2,
The image forming apparatus, wherein the controller makes the rotation time of the developer carrier in the rotation operation constant regardless of a period of use of the developing device. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the controller increases only the rotation time of the rotation time and rotation speed of the developer carrying member in the rotation operation as the use period of the developing device becomes longer. The image forming apparatus according to any one of claims 1 to 4,
The controller is configured to increase at least one of a rotation time and a rotation speed of the developer carrier in the rotation operation as the accumulated rotation time of the rotation of the developer carrier becomes longer. apparatus. An image forming apparatus according to any one of claims 1 to 5,
The image forming apparatus, wherein the latent image is not carried on the image carrier during the preliminary preparation operation. The image forming apparatus according to claim 1, wherein:
2. The image forming apparatus according to claim 1, wherein the developing device includes a scraping member that rotates while being in contact with the developer carrier and scrapes off the developer on the developer carrier. (A) an image carrier for carrying a latent image;
(B) a developing device comprising a rotatable developer carrying member for carrying the developer, and developing the latent image carried on the image carrier by the developer carried on the developer carrying member;
(C) a controller that executes a rotation operation of the developer carrying member as a pre-preparation operation of the development in order to prevent occurrence of density unevenness during the development of the latent image by the developing device, A controller that increases at least one of a rotation time and a rotation speed of the developer carrying member in the rotation operation as a use period of the developing device becomes longer;
(D)
(E) The controller increases only the rotation speed of the rotation time and rotation speed of the developer carrying member in the rotation operation as the use period of the developing device becomes longer,
(F) the controller sets a constant rotation time of the developer carrier in the rotation operation regardless of a period of use of the developing device;
(G) The controller increases at least one of a rotation time and a rotation speed of the developer carrier in the rotation operation as the accumulated rotation time of the rotation of the developer carrier increases.
(H) During the preliminary preparation operation, the latent image is not carried on the image carrier,
(I) The image forming apparatus characterized in that the developing device includes a scraping member for rotating in a state of being in contact with the developer carrier and scraping off the developer on the developer carrier. apparatus. (A) a computer, and
(B) An image forming apparatus connected to the computer,
An image carrier for carrying a latent image;
A developing device comprising a rotatable developer carrier for carrying the developer, and developing the latent image carried on the image carrier by the developer carried on the developer carrier;
A controller that executes a rotation operation of the developer carrying member as a pre-preparation operation of the development in order to prevent occurrence of density unevenness during development of the latent image by the developing device; A controller that increases at least one of a rotation time and a rotation speed of the developer carrying member in the rotation operation as a use period becomes longer;
An image forming apparatus having
An image forming system comprising (C).

Images