JP2007286257A - Image forming apparatus and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image forming apparatus where residual developer is appropriately removed by a removal member for restarting an image forming operation, and an image forming system. <P>SOLUTION: The image forming apparatus includes the removal member provided on a downstream side in the rotating direction of an intermediate transfer body as seen from a secondary transfer part, and removing the residual developer remaining on the intermediate transfer body while abutting on the intermediate transfer body. It includes a control part which controls not to supply transfer voltage by a first transfer voltage supply part when the residual developer positioned on an upstream side in the rotating direction of the intermediate transfer body as seen from the secondary transfer part and positioned between a primary transfer part and the secondary transfer part when a phenomenon that the image forming operation is stopped midway occurs is removed by the removal member in order to restart the image forming operation. <P>COPYRIGHT: (C)2008,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, a photosensitive member capable of carrying a developer, a rotatable intermediate transfer member serving as an intermediate medium when the developer on the photosensitive member is transferred to a medium, and development on the photosensitive member. A voltage supply unit that supplies the intermediate transfer member with a transfer voltage for directing the agent to the intermediate transfer member at the primary transfer unit, and a developer that has moved to the secondary transfer unit as the intermediate transfer member rotates. A secondary transfer member for transferring to a medium. The photoconductor also has a function of carrying a latent image.

  When the image forming apparatus receives an image signal or the like from an external device such as a host computer, the latent image carried on the photoconductor is developed with, for example, a developer in the developing device. The developer on the photoreceptor is primarily transferred so as to be attracted to the intermediate transfer member to which the transfer voltage is supplied by the voltage supply unit, and then secondarily transferred to the medium by the secondary transfer member. The developer secondarily transferred to the medium is further fixed to the medium by a fixing device, and finally an image is formed on the medium.

  Further, the image forming apparatus is further provided on the downstream side in the rotation direction of the intermediate transfer member as viewed from the secondary transfer unit, contacts the intermediate transfer member, and remains on the intermediate transfer member. A removal member for removing the agent. This removing member removes the developer remaining on the intermediate transfer member without being transferred onto the medium by the secondary transfer member during image formation.

Incidentally, during execution of an image forming operation, an event that stops the image forming operation halfway may occur. As the event, for example, there is an event that the medium is jammed while being conveyed through the image forming apparatus during the image forming operation (this jam of the medium is hereinafter referred to as “jam”). In such a case, the remaining developer on the intermediate transfer member is removed by the removing member after the jam is eliminated by removing the jammed medium in the image forming apparatus by an operator or the like to restart the image forming operation. Removed. Conventionally, when the residual developer on the intermediate transfer member is removed by the removing member after the jam is eliminated, a transfer voltage is supplied to the intermediate transfer belt.
JP 2002-169389 A

  When an event that stops the image forming operation in the middle (such as a jam of the medium) occurs, the primary transfer unit and the secondary transfer unit are upstream of the intermediate transfer member in the rotation direction as viewed from the secondary transfer unit. Residual developer may be located between the transfer portion. In such a case, since the residual developer is removed by the removal member for resuming the image forming operation, the amount of residual developer to be removed by the removal member tends to increase.

  Then, when a large amount of residual developer is removed by the removing member for resuming the image forming operation, a transfer voltage for supplying the developer to the intermediate transfer member is supplied to the intermediate transfer member as described above. As a result, a large amount of residual developer remaining on the intermediate transfer member is attracted to the intermediate transfer member. In such a case, the residual developer may remain on the intermediate transfer member as it is without being properly removed by the removing member.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus in which residual developer is appropriately removed by a removing member for resuming an image forming operation, and an image. The realization of the forming system.

  In order to solve the above-mentioned problems, the main present invention is: (a) a photosensitive member capable of supporting a developer; and (b) a rotatable medium serving as an intermediate medium when transferring the developer on the photosensitive member to the medium. An intermediate transfer member; and (c) a voltage supply unit that supplies a transfer voltage for directing the developer on the photosensitive member to the intermediate transfer member at a primary transfer unit; A secondary transfer member for transferring the developer that has moved to the secondary transfer portion with the rotation of the intermediate transfer member to the medium; and (e) downstream of the intermediate transfer member in the rotation direction as viewed from the secondary transfer portion. An image forming apparatus provided with (a) a removing member provided in contact with the intermediate transfer member to remove residual developer remaining on the intermediate transfer member, and (g) the voltage supply unit A control unit for controlling when an event that stops the image forming operation is generated. The residual developer that is located upstream of the intermediate transfer member in the rotational direction as viewed from the secondary transfer unit and located between the primary transfer unit and the secondary transfer unit is restarted. Therefore, the image forming apparatus includes a control unit that prevents the voltage supply unit from supplying the transfer voltage when the removal member removes the transfer voltage.

  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.

  (A) a photosensitive member capable of carrying a developer, (b) a rotatable intermediate transfer member serving as an intermediate medium when transferring the developer on the photosensitive member to a medium, and (c) on the photosensitive member. A voltage supply unit for supplying the intermediate transfer member with a transfer voltage for directing the developer to the intermediate transfer member at the primary transfer unit; and (d) moving to the secondary transfer unit as the intermediate transfer member rotates. A secondary transfer member for transferring the developed developer to the medium, and (e) provided on the downstream side in the rotational direction of the intermediate transfer member as viewed from the secondary transfer portion, abutting on the intermediate transfer member, An image forming apparatus comprising: a removal member that removes residual developer remaining on the intermediate transfer member; and (f), and (g) a control unit for controlling the voltage supply unit, the image forming operation Rotation of the intermediate transfer member when viewed from the secondary transfer portion When the residual developer located on the improved flow side and located between the primary transfer portion and the secondary transfer portion is removed by the removal member for resuming the image forming operation, An image forming apparatus comprising: a control unit that does not execute supply of the transfer voltage by the voltage supply unit.

  When an event that stops the image forming operation in the middle occurs, the control unit is located on the upstream side in the rotation direction of the intermediate transfer member as viewed from the secondary transfer unit, and the primary transfer unit and the secondary transfer unit When the residual developer positioned between the transfer portion and the transfer member is removed by the removing member for resuming the image forming operation, if the supply of the transfer voltage by the voltage supply portion is not executed, the residual development is performed. The force to attract the agent to the intermediate transfer member does not work. For this reason, the residual developer is appropriately removed by the removing member for resuming the image forming operation.

  Further, in this image forming apparatus, the voltage supply unit supplies the developer to the intermediate transfer body with the transfer voltage for directing the developer to the intermediate transfer body, and the developer from the intermediate transfer body. A reverse transfer voltage for separation can be supplied to the intermediate transfer member, and the control unit can detect the intermediate transfer unit as viewed from the secondary transfer unit when an event for stopping the image forming operation occurs halfway. Residual developer located on the upstream side in the rotation direction of the transfer body and located between the primary transfer portion and the secondary transfer portion is removed by the removal member for resuming the image forming operation. At this time, the reverse transfer voltage may be supplied by the voltage supply unit.

  When an event for stopping the image forming operation occurs halfway, it is located upstream in the rotation direction of the intermediate transfer member as viewed from the secondary transfer unit, and the primary transfer unit and the secondary transfer unit When supply of a reverse transfer voltage by the voltage supply unit is executed when the residual developer located between them is removed by the removing member for resuming the image forming operation, the residual developer A force is generated that separates the toner from the intermediate transfer member. For this reason, it becomes easy to appropriately remove the residual developer by the removing member for resuming the image forming operation.

In the image forming apparatus, the control unit may be viewed from a developer removing unit that removes residual developer by the removing member when an event that stops the image forming operation is generated. Residual developer located upstream of the intermediate transfer member in the rotation direction and located between the primary transfer portion and the developer removing portion is removed by the removing member for resuming the image forming operation. In this case, the supply of the transfer voltage by the voltage supply unit may not be executed.
When an event that stops the image forming operation occurs halfway, residual developer remaining on the intermediate transfer member without being transferred to the medium in the secondary transfer unit before the occurrence of the event is transferred from the developer removing unit. As seen, the intermediate transfer member may be located upstream in the rotation direction and between the secondary transfer portion and the developer removing portion. In this case, when the residual developer is removed by the removal member for resuming the image forming operation, if the supply of the transfer voltage by the voltage supply unit is not executed, the residual developer is also removed. It will be removed appropriately by the member.

In the image forming apparatus, the voltage supply unit may supply the transfer voltage over the entire intermediate transfer body.
In the case where the transfer voltage is supplied to the entire intermediate transfer member, the effect of not supplying the transfer voltage when the residual developer is removed, that is, the removal for resuming the image forming operation. The effect that the residual developer is appropriately removed by the member is more effectively exhibited.

  Also, in this image forming apparatus, an electrode layer is provided at an end of the intermediate transfer member perpendicular to the rotation direction of the intermediate transfer member, and the conductive member is in contact with the electrode layer The voltage supply unit may supply the transfer voltage to the intermediate transfer member via the conductive member.

In addition, the image forming apparatus includes four photoconductors capable of carrying developers of different colors, and the intermediate transfer body is configured to transfer the developer on each of the photoconductors to a medium. It may be an intermediate medium.
In such a case, since the four color developers are transferred onto the intermediate transfer member, the amount of developer removed by the removal member immediately after an event that stops the image forming operation is increased. Cheap. For this reason, the effect that the supply of the transfer voltage is not executed when the residual developer is removed, that is, the effect that the residual developer is appropriately removed by the removing member for resuming the image forming operation, Played more effectively.

(A) a photosensitive member capable of supporting the developer; (b) a rotatable intermediate transfer member serving as an intermediate medium when transferring the developer on the photosensitive member to the medium; and (c) the photosensitive member. A voltage supply unit for supplying a transfer voltage for directing the developer on the intermediate transfer member to the intermediate transfer member at the primary transfer unit; and (d) a secondary transfer unit as the intermediate transfer member rotates. A secondary transfer member for transferring the developer moved to the medium to the medium, and (e) provided on the downstream side in the rotation direction of the intermediate transfer member as viewed from the secondary transfer portion, and in contact with the intermediate transfer member An image forming apparatus comprising: (f) a removing member that removes residual developer remaining on the intermediate transfer body; and (g) a control unit for controlling the voltage supply unit. The intermediate transfer member as viewed from the secondary transfer portion when an event that stops the forming operation is generated When the residual developer located on the upstream side in the rotation direction and located between the primary transfer portion and the secondary transfer portion is removed by the removal member for resuming the image forming operation. A control unit that does not execute the supply of the transfer voltage by the voltage supply unit, and (h) the voltage supply unit is configured to transfer the developer to the intermediate transfer member, and to transfer the intermediate transfer member with the transfer voltage. The reverse transfer voltage for separating the developer from the intermediate transfer member can be supplied to the intermediate transfer member together with the supply to the intermediate transfer member, and an event has occurred in which the control unit stops the image forming operation halfway. Sometimes, the residual developer located upstream in the rotational direction of the intermediate transfer member as viewed from the secondary transfer portion and located between the primary transfer portion and the secondary transfer portion is the image forming unit. In order to resume operation, the removal member When the removal is performed, supply of the reverse transfer voltage by the voltage supply unit is executed, and (i) the control unit is caused to remain by the removal member when an event for stopping the image forming operation occurs halfway. A residual developer located between the primary transfer portion and the developer removing portion, located on the upstream side in the rotation direction of the intermediate transfer member as viewed from the developer removing portion where the developer is removed; Is removed by the removal member for resuming the image forming operation, the supply of the transfer voltage by the voltage supply unit is not executed, and (j) the voltage supply unit (K) An electrode layer is provided at the end of the intermediate transfer member perpendicular to the rotation direction of the intermediate transfer member, and the conductive layer is in contact with the electrode layer. A voltage member, the voltage supply unit The transfer voltage is supplied to the intermediate transfer member via a conductive member, and (l) four photoconductors capable of carrying developers having different colors from each other, and the intermediate transfer member includes each of the photosensitive members. An image forming apparatus that serves as an intermediate medium for transferring a developer on a body onto a medium.
According to such an image forming apparatus, the effect that the residual developer is appropriately removed by the removing member for resuming the image forming operation is most effectively exhibited.

(A) a computer; and (B) an image forming apparatus connectable to the computer, wherein (a) a photoconductor capable of carrying a developer, and (b) a developer on the photoconductor as a medium. A rotatable intermediate transfer member serving as an intermediate medium when transferring to the medium, and (c) a transfer voltage for directing the developer on the photosensitive member to the intermediate transfer member in a primary transfer portion. (D) a secondary transfer member for transferring the developer that has moved to the secondary transfer unit with the rotation of the intermediate transfer member to a medium, and (e) from the secondary transfer unit An image forming apparatus comprising: (f) a removing member that is provided on the downstream side in the rotation direction of the intermediate transfer member as viewed and contacts the intermediate transfer member to remove residual developer remaining on the intermediate transfer member; (G) a control unit for controlling the voltage supply unit, wherein the image type When an event for stopping the operation occurs halfway, it is located upstream in the rotation direction of the intermediate transfer member when viewed from the secondary transfer unit, and between the primary transfer unit and the secondary transfer unit. An image forming apparatus comprising: a control unit that prevents supply of the transfer voltage by the voltage supply unit when residual developer located is removed by the removal member for resumption of the image forming operation; An image forming system comprising (C).
According to such an image forming system, the residual developer is appropriately removed by the removing member for resuming the image forming operation.

=== Overview of Image Forming Apparatus ===
Next, a configuration example and an operation example will be described with reference to FIGS. 1 to 3 by 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. FIG. 2 is a block diagram illustrating the configuration of the control unit 100 of the printer 10. FIG. 3 is a diagram showing the image forming unit 15Y. 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. Similarly, in FIG. 3, the vertical direction is indicated by arrows.

<<< Configuration of Printer 10 >>>
As shown in FIG. 1, the printer 10 according to the present embodiment includes image forming units 15Y, 15M, 15C, and 15K, an intermediate transfer belt 70 as an example of an “intermediate transfer member”, a primary transfer unit 60, and a backup roller 65Y. , 65M, 65C, 65K, secondary transfer unit 80, intermediate transfer belt cleaning unit 85, fixing unit 90, display means 95 having a notification means to the user and a liquid crystal panel, and these units are controlled as a printer. Has a control unit 100 for controlling the operation.

  The image forming units 15Y, 15M, 15C, and 15K have a function of forming latent images and toner images on the photoconductors 20Y, 20M, 20C, and 20K. These four image forming portions 15Y, 15M, 15C, and 15K are arranged in a row in a predetermined direction (the horizontal direction shown in FIG. 1). Since the image forming units 15Y, 15M, 15C, and 15K have the same configuration, the image forming unit 15Y of the four image forming units will be described below as an example.

  As shown in FIG. 3, the image forming unit 15Y includes a charging unit 30Y, an exposure unit 40Y, a developing unit 50Y, and a photoreceptor cleaning unit 75Y along the rotation direction of the photoreceptor 20Y.

  The photoreceptor 20Y has a cylindrical base material (specifically, an aluminum material) and a photosensitive layer formed on the outer peripheral surface thereof, and carries a latent image on the surface of the photosensitive layer. Both ends in the axial direction of the photoconductor 20Y are rotatably supported by the printer main body. In this embodiment, the photoconductor 20Y rotates clockwise as indicated by an arrow in FIG.

  The charging unit 30Y is a device for charging the photoconductor 20Y. As shown in FIG. 3, the charging unit 30Y opposes the photosensitive member 20Y and charges the photosensitive member 20Y. The charging unit 30Y contacts the charging roller 31Y and cleans the surface of the charging roller 31Y. And a cleaning roller 35Y. When a charging bias in which a DC voltage and an AC voltage are superimposed is supplied from the charging bias supply unit 121 (FIG. 2) to the charging roller 31Y, a discharge occurs between the charging roller 31Y and the photoconductor 20Y. As a result, the photoconductor 20Y is charged.

  The charging roller 31Y has a configuration in which a conductive paint is applied to the surface of a metal shaft. Further, the charging roller 31Y is attached with tape (not shown) that contacts the photoconductor 20Y at both ends in the axial direction. Since the outer diameter of the tape is larger than the outer diameter of the central portion of the charging roller 31Y, a gap is formed between the central portion and the photoreceptor 20Y. Therefore, the charging roller 31Y charges the photoreceptor 20Y by a so-called non-contact charging method.

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

  The yellow developing unit 50Y is a device for visualizing the latent image formed on the photoreceptor 20Y as a yellow toner image using yellow (Y) toner, which is an example of “developer”, in the developing unit A1. . As shown in FIG. 3, the yellow developing unit 50Y includes a toner containing portion 51Y for containing yellow toner, and a developing roller 52Y for carrying the yellow toner and developing a latent image on the photoreceptor 20Y. , A supply roller 53Y for supplying the toner in the toner container 51Y to the developing roller 52Y, and a regulating blade for charging the yellow toner carried on the developing roller 52Y (in this embodiment, the toner is negatively charged) (Not shown).

  The developing roller 52Y faces the photoconductor 20Y through a gap, and when a developing bias in which a DC voltage and an AC voltage are superimposed is supplied from the developing bias supply unit 122 (FIG. 2) to the developing roller 52Y, An electric field is formed between the developing roller 52Y and the photoreceptor 20Y, and the latent image on the photoreceptor 20Y is developed.

  The intermediate transfer belt 70 is an intermediate medium for transferring toner images (toner) carried on the four photoconductors 20Y, 20M, 20C, and 20K to a “medium” (paper, film, cloth, etc.). The toner image is moved by rotating in a state where the toner image is carried. The intermediate transfer belt 70 is in contact with the photoconductors 20Y, 20M, 20C, and 20K, and the toner image on the photoconductor is transferred to the contact portion between the intermediate transfer belt 70 and the photoconductor. Primary transfer portions B1, B2, B3, and B4 to be transferred to 70 are formed. The detailed configuration of the intermediate transfer belt 70 will be described later.

  The primary transfer unit 60 (FIG. 4) transfers toner images formed on the photoreceptors 20Y, 20M, 20C, and 20K to the intermediate transfer belt 70 in cooperation with backup rollers 65Y, 65M, 65C, and 65K (described later). (Hereinafter also referred to as primary transfer). The primary transfer unit 60 is in contact with the intermediate transfer belt 70, and the primary transfer bias supply unit 123 a (FIG. 2) of the voltage supply unit 123 is connected to the primary transfer bias that is “transfer voltage” via the primary transfer unit 60. Is supplied to the intermediate transfer belt 70.

  Here, the primary transfer bias is a voltage for directing the toner on the photoreceptors 20Y, 20M, 20C, and 20K to the intermediate transfer belt 70 at the primary transfer portions B1, B2, B3, and B4. The primary transfer bias is a voltage having a polarity opposite to the charging polarity (negative polarity) of the toner on the photoreceptor. When a primary transfer bias is supplied to the intermediate transfer belt 70, an electric field is formed between the photoreceptors 20Y, 20M, 20C, and 20K and the intermediate transfer belt 70 in the primary transfer portions B1, B2, B3, and B4. The Details of the primary transfer unit 60 and the voltage supply unit 123 will be described later.

  The backup rollers 65Y, 65M, 65C, and 65K are in contact with the photoreceptors 20Y, 20M, 20C, and 20K of the four image forming units 15Y, 15M, 15C, and 15K via the intermediate transfer belt 70, respectively. Then, the backup rollers 65Y, 65M, 65C, and 65K come into contact with the photoreceptors 20Y, 20M, 20C, and 20K via the intermediate transfer belt 70, and the primary transfer portions B1, B2, B3, and B4 as described above. When an electric field is formed between the photosensitive member and the intermediate transfer belt 70, the toner images on the photosensitive members 20Y, 20M, 20C, and 20K are sequentially transferred to the intermediate transfer belt 70 in the primary transfer portions B1, B2, B3, and B4. Transcribed. As a result, a full color toner image is formed on the intermediate transfer belt 70.

  The photoreceptor cleaning unit 75Y is a device for removing and collecting the toner remaining on the photoreceptor 20Y after the toner image is transferred onto the intermediate transfer belt 70 by the primary transfer unit 60. The photoreceptor cleaning unit 75Y has a photoreceptor cleaning blade 76Y. The front end of the photoreceptor cleaning blade 76Y contacts the surface of the photoreceptor 20Y, and removes the toner image (toner) left on the photoreceptor 20Y without being transferred to the intermediate transfer belt 70.

  The secondary transfer unit 80 is a device for transferring a single color toner image or a full color toner image formed on the intermediate transfer belt 70 to a medium (hereinafter also referred to as secondary transfer). The secondary transfer unit 80 has a secondary transfer roller 82 that can be brought into and out of contact with the intermediate transfer belt 70, and the secondary transfer roller 82 is in a secondary transfer portion C 1 that contacts the intermediate transfer belt 70 through a medium. The toner image on the intermediate transfer belt 70 is secondarily transferred to the medium. Specifically, when the secondary transfer bias is supplied from the secondary transfer bias supply unit 124 (FIG. 2) to the secondary transfer roller 82, the intermediate transfer belt 70, the secondary transfer roller 82, and the like at the secondary transfer unit C1. An electric field is formed between the toner images and the toner image on the intermediate transfer belt 70 is secondarily transferred to the medium.

  The intermediate transfer belt cleaning unit 85 is a device for removing toner remaining on the intermediate transfer belt 70 without being secondarily transferred to the medium in the secondary transfer portion C1. The intermediate transfer belt cleaning unit 85 includes a storage portion 86 for storing the removed toner, and an intermediate transfer belt cleaning blade 87 as an example of a “removal member”.

  The intermediate transfer belt cleaning blade 87 is provided on the downstream side in the rotation direction of the intermediate transfer belt 70 when viewed from the secondary transfer portion C1. The end of the intermediate transfer belt cleaning blade 87 abuts on the surface of the intermediate transfer belt 70 and removes toner remaining on the intermediate transfer belt 70 without being secondarily transferred to the medium at the secondary transfer portion C1. Further, the intermediate transfer belt cleaning blade 87 is in contact with the intermediate transfer belt 70 so that the tip thereof faces the upstream side in the rotation direction of the intermediate transfer belt 70.

  The fixing unit 90 is a device that heats and presses a single-color toner image or a full-color toner image transferred onto a medium and fuses it to the medium to form a permanent image. The fixing unit 90 includes a fixing roller 90a and a pressure roller 90b. The fixing roller 90a is for heating the toner image on the medium and fusing the toner image to the medium. The pressure roller 90b is for pressing the toner image on the medium in cooperation with the fixing roller 90a.

  A medium transport path 13 for transporting the medium in the paper feed tray 92 to the paper discharge tray 98 is formed from the lower part to the upper part of the printer 10. The medium transport path 13 is composed of a large number of guide members. A plurality of rollers such as a paper feed roller 94a, a registration roller 94b, and a paper discharge roller 94c, each having a function of transporting a medium, are disposed on the medium transport path 13. On the medium transport path 13, four medium detection sensors 14a, 14b, 14c, and 14d for detecting the medium transported along the medium transport path 13 by the plurality of rollers are arranged.

  A cover 12 that can be opened and closed is provided on the front side of the printer 10. For example, when a medium is jammed on the medium conveyance path 13, an operator or the like opens the cover 12 in the front direction of the paper in FIG. 1 to remove the jammed medium. Further, an opening / closing detection sensor (not shown) for detecting the opening / closing of the cover 12 is provided in the periphery of the cover 12.

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

<<< Operation of Printer 10 >>>
Next, the color image forming operation of the printer 10 configured as described above will be described with reference to other components.

  First, when an image signal and a control signal from a host computer (not shown) are input to the main controller 101 of the printer 10 via the interface (I / F) 112, the unit controller 102 based on a command from the main controller 101. By the control, the developing rollers 52Y, 52M, 52C, 52K and the intermediate transfer belt 70 provided in the photosensitive members 20Y, 20M, 20C, 20K, the developing units 50Y, 50M, 50C, 50K, and the like rotate.

  The photoreceptors 20Y, 20M, 20C, and 20K are sequentially charged by the charging units 30Y, 30M, 30C, and 30K (specifically, the charging rollers 31Y, 31M, 31C, and 31K to which a charging bias is supplied) at the charging position while rotating. Is done. The charged regions of the photoconductors 20Y, 20M, 20C, and 20K reach the exposure position as the photoconductors 20Y, 20M, 20C, and 20K rotate, and are exposed to yellow Y and magenta by the exposure units 40Y, 40M, 40C, and 40K. A latent image corresponding to the image information of M, cyan C, and black K is formed in the area.

  The latent images formed on the photoconductors 20Y, 20M, 20C, and 20K reach the developing units A1, A2, A3, and A4 as the photoconductors 20Y, 20M, 20C, and 20K rotate, and develop units 50Y, 50M, and The toner images are visualized (developed) by 50C and 50K (specifically, the developing rollers 52Y, 52M, 52C, and 52K). Thereby, monochromatic toner images are formed on the photoconductors 20Y, 20M, 20C, and 20K. In developing, a developing bias is supplied to the developing rollers 52Y, 52M, 52C, and 52K.

  The monochromatic toner images formed on the photoconductors 20Y, 20M, 20C, and 20K reach the primary transfer portions B1, B2, B3, and B4 as the photoconductors 20Y, 20M, 20C, and 20K rotate, and the primary transfer unit 60. And the backup rollers 65Y, 65M, 65C, and 65K. At this time, a primary transfer bias is supplied to the intermediate transfer belt 70. As a result, the four-color toner images formed on the respective photoconductors 20Y, 20M, 20C, and 20K are primarily transferred so as to sequentially overlap the intermediate transfer belt 70, and a full-color toner image is formed on the intermediate transfer belt 70. It is formed.

  The full-color toner image formed on the intermediate transfer belt 70 reaches the secondary transfer portion C1 as the intermediate transfer belt 70 rotates, and is transferred to the medium by the secondary transfer unit 80 (specifically, the secondary transfer roller 82). Next is transferred. The medium is conveyed from the paper feed tray 92 to the secondary transfer unit C1 via the paper feed roller 94a and the registration roller 94b. Further, when performing the secondary transfer operation, the secondary transfer roller 82 cooperates with the intermediate transfer belt 70 to hold the medium conveyed to the secondary transfer portion C1, and to the secondary transfer roller 82, A next transfer bias is supplied.

  When the medium on which the full-color toner image is secondarily transferred is conveyed into the fixing unit 90, the medium is sandwiched between the fixing roller 90a and the pressure roller 90b between the fixing roller 90a and the pressure roller 90b. pass. At this time, the fixing roller 90a and the pressure roller 90b heat and press the full color toner image on the medium, so that the full color toner image is fused to the medium. The medium on which the full-color toner image is fused is conveyed to the paper discharge tray 98 via the paper discharge roller 94c.

  On the other hand, the toner remaining on the photoconductors 20Y, 20M, 20C, and 20K without being primarily transferred to the intermediate transfer belt 70 at the primary transfer portions B1, B2, B3, and B4 is the photoconductor cleaning blades 76Y, 76M, and 76C. Removed by 76K. Further, the toner remaining on the intermediate transfer belt 70 without being secondarily transferred to the medium in the secondary transfer portion C1 is removed by the intermediate transfer belt cleaning blade 87.

=== Overview of Control Unit ===
Next, the configuration of the control unit 100 will be described with reference to FIG. The main controller 101 of the control unit 100 is connected to a host computer via an interface 112 and includes an image memory 113 for storing image signals input from the host computer.

  The unit controller 102 includes units (photoconductors 20Y, 20M, 20C, and 20K, charging units 30Y, 30M, 30C, and 30K, exposure units 40Y, 40M, 40C, and 40K, developing units 50Y, 50M, 50C, and 50K). , Primary transfer unit 60, intermediate transfer belt 70, photoreceptor cleaning units 75Y, 75M, 75C, 75K, secondary transfer unit 80, intermediate transfer belt cleaning unit 85, fixing unit 90, and display unit 95). Each unit is controlled based on the signal input from the main controller 101 while detecting the state of each unit by receiving signals from the sensors included in them.

=== Regarding Intermediate Transfer Belt 70, Primary Transfer Unit 60, and Voltage Supply Unit 123 ===
Next, the intermediate transfer belt 70, the primary transfer unit 60, and the voltage supply unit 123 will be described with reference to FIGS. 2 and 4 to 6. FIG. 4 is a diagram showing the intermediate transfer belt 70 and the like. FIG. 5 is a schematic view showing a part of the outer peripheral surface of the intermediate transfer belt 70. FIG. 6 is a diagram illustrating a contact state between the intermediate transfer belt 70 and the primary transfer unit 60.

<<< Detailed Configuration of Intermediate Transfer Belt 70 >>>
As described above, the intermediate transfer belt 70 is an intermediate medium when transferring the toner (toner image) on the photoreceptors 20Y, 20M, 20C, and 20K to a medium (paper, film, cloth, etc.), and the toner is transferred to the medium. In order to transfer the toner, the toner is moved by rotating in a state where the toner is carried.

  The intermediate transfer belt 70 is formed by providing a tin vapor deposition layer on the surface of a PET film, and forming a semiconductive paint on the surface layer (hereinafter, the semiconductive paint layer is also referred to as a resistance layer 70a (FIG. 5)) and laminating it. It is a belt. Further, at one end of the intermediate transfer belt 70 in an orthogonal direction (hereinafter also referred to as a belt orthogonal direction) orthogonal to the rotation direction of the intermediate transfer belt 70 (the direction indicated by the arrow in FIG. 5), the resistance layer 70a Instead, the electrode layer 70 b is formed along the rotation direction of the intermediate transfer belt 70. The toner on the photoconductors 20Y, 20M, 20C, and 20K is primarily transferred to the resistance layer 70a at the primary transfer portions B1, B2, B3, and B4.

  A bead 70c (see FIG. 6) that protrudes to the inside of the intermediate transfer belt 70 is fixed to the inner peripheral surface of the intermediate transfer belt 70 and both ends in the belt orthogonal direction. The bead 70 c is provided over substantially the entire circumference of the intermediate transfer belt 70 along the rotation direction of the intermediate transfer belt 70.

  In addition to the backup rollers 65Y, 65M, 65C, and 65K described above, a driving roller 71a, a driven roller 71b, a roller 71c, a roller 71d, and the like are provided inside the intermediate transfer belt 70. The driving roller 71a is in contact with the inner peripheral surface of the intermediate transfer belt 70 and has a function of rotating the intermediate transfer belt 70 at substantially the same peripheral speed as the photoconductors 20Y, 20M, 20C, and 20K. The driven roller 71b, the roller 71c, and the roller 71d are in contact with the inner peripheral surface of the intermediate transfer belt and stretch the intermediate transfer belt 70 in a rotatable manner.

  The driven roller 71b is in contact with the central portion of the intermediate transfer belt 70 in the belt orthogonal direction, and is provided with a rotating member 73 that can rotate with respect to the driven roller 71b at both ends in the axial direction. The rotating member 73 has a tapered portion 73a on the driven roller 71b side, and the tapered portion 73a contacts the bead 70c, thereby restricting the movement of the intermediate transfer belt 70 in the belt orthogonal direction.

<<< Detailed Configuration of Primary Transfer Unit 60 >>>
As described above, the primary transfer unit 60 is in contact with the intermediate transfer belt 70. As shown in FIG. 6, the primary transfer unit 60 includes an electrode roller 210 as an example of a “conductive member”, a roller bearing 220 that rotatably receives the electrode roller 210, and a electrode roller 210 that rotatably supports the electrode roller 210. And a roller support sheet metal 230.

  The electrode roller 210 contacts the electrode layer 70b of the intermediate transfer belt 70 as shown in FIG. The electrode roller 210 is configured to rotate with the rotation of the intermediate transfer belt 70 while being in contact with the electrode layer 70b. That is, the electrode roller 210 is a driven roller that rotates with the rotation of the intermediate transfer belt 70. The electrode roller 210 is provided at a position facing the bead 70c through the intermediate transfer belt 70.

  Further, as shown in FIG. 6, the electrode roller 210 includes a contact portion 211 that is in contact with the electrode layer 70 b of the intermediate transfer belt 70, and a roller shaft 212 whose outer diameter is smaller than the outer diameter of the corresponding contact portion 211. I have. The abutting portion 211 is an elastic roller having conductivity, and is made of, for example, a single-foam foam in which carbon as a conductive agent is dispersed in urethane. The roller shaft 212 is made of metal, and one end side 212a in the axial direction is positioned on the center side of the intermediate transfer belt 70 in the belt orthogonal direction, and the other end side 212b in the axial direction is in the intermediate transfer belt 70 in the belt orthogonal direction. It is provided so that it may be located in the end side.

  As shown in FIG. 6, the roller bearing 220 is attached to a roller support metal plate 230 and rotatably receives one end side 212 a of the roller shaft 212 of the electrode roller 210. The roller support metal plate 230 is made of metal, and as shown in FIG. 6, supports one end side 212a of the roller shaft 212 of the electrode roller 210 via the roller bearing 220, and supports the other end side 212b of the roller shaft 212. Support directly.

<<< Regarding Voltage Supply Unit 123 >>>
As described above, the primary transfer bias is supplied from the voltage supply unit 123 to the intermediate transfer belt 70 via the primary transfer unit 60. The voltage supply unit 123 supplies the primary transfer bias to the intermediate transfer belt 70 and, at the same time, the reverse transfer bias intermediate transfer belt 70, which is a “reverse transfer voltage” for separating the toner on the intermediate transfer belt 70 from the intermediate transfer belt 70. Supply to is also possible. The voltage supply unit 123 supplies a primary transfer bias or a reverse transfer bias over the entire intermediate transfer belt 70 via the primary transfer unit 60.

  As shown in FIG. 2, the voltage supply unit 123 includes a primary transfer bias supply unit 123a and a reverse transfer bias supply unit 123b. The primary transfer bias supply unit 123 a is for supplying the primary transfer bias to the intermediate transfer belt 70. The reverse transfer bias supply unit 123 b is for supplying a reverse transfer bias to the intermediate transfer belt 70. During the operation of the printer 10, either the primary transfer bias supply unit 123a or the reverse transfer bias supply unit 123b supplies the primary transfer bias or the reverse transfer bias to the intermediate transfer belt 70, or the primary transfer bias. Neither the supply unit 123 a nor the reverse transfer bias supply unit 123 b supplies the primary transfer bias or the reverse transfer bias to the intermediate transfer belt 70.

=== Regarding Operation of Printer 10 When Jam Occurs During Image Formation ===
In the printer 10, during the execution of the image forming operation, an event that stops the image forming operation halfway may occur. Examples of such an event include an event in which the cover 12 is opened by an operator or the like during an image forming operation, and an event in which the medium is jammed on the medium transport path 13 during an image forming operation (so-called media jam). Here, a description will be given by taking the jam of the medium as an example.

  For example, during the execution of the image forming operation, the medium may be jammed between the intermediate transfer belt 70 and the secondary transfer roller 82 in the secondary transfer portion C1. If a medium jam occurs during the image forming operation, the printer 10 stops the image forming operation halfway. For this reason, in order to restart the image forming operation, it is necessary to remove the jammed medium and thereby remove the jam.

  Incidentally, when the operation of the printer 10 during image formation is stopped due to the occurrence of a jam of the medium, residual toner is present between the primary transfer portion (for example, the primary transfer portion B1) and the secondary transfer portion C1. May be located. Further, residual toner may be located between the developing unit A1 (A2, A3, A4) and the primary transfer unit B1 (B2, B3, B4) on each photoconductor 20Y (20M, 20C, 20K). (See FIG. 9A). In such a case, the residual toner needs to be removed by the photoconductor cleaning blades 76Y, 76M, 76C, and 76K and the intermediate transfer belt cleaning blade 87 so that the image can be formed again after the jam is removed.

  Therefore, the printer 10 executes the following operation when a medium jam occurs. In other words, the printer 10 informs the operator of the occurrence of jam in order to remove the jammed medium, and after the jammed medium is removed (that is, after the jam is cleared), the photoconductors 20Y, 20M, The residual toner is removed by the photoconductor cleaning blade and the intermediate transfer belt cleaning blade by rotating the 20C and 20K and the intermediate transfer belt 70.

<<< Example of Operation of Printer 10 >>>
In the above description, the normal image forming operation in which jam does not occur has been described. Here, the operation of the printer 10 when jam occurs during image formation will be described with reference to FIG. explain. FIG. 7 is a flowchart for explaining the operation of the printer 10 when a jam occurs during image formation.

  Various operations when the operation of the printer 10 is executed are mainly realized by the control unit 100 (FIG. 3) as an example of the “control unit”. 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 receiving the image signal and the control signal from the host computer, the control unit 100 starts the above-described image forming operation (step s102). Here, it is assumed that a color image is formed on one medium.

  If the control unit 100 determines that a medium jam has occurred on the medium conveyance path 13 during color image formation via the medium detection sensors 14a, 14b, 14c, and 14d (step s104: Yes), The operation of the printer 10 is stopped (step s106). In this embodiment, it is assumed that the medium is jammed between the intermediate transfer belt 70 and the secondary transfer roller 82 (see FIG. 9A). Then, the control unit 100 stops the rotation of the photoconductors 20Y, 20M, 20C, 20K, the intermediate transfer belt 70, and the like (see FIGS. 8 and 10), and separates the secondary transfer roller 82 from the intermediate transfer belt 70. The control unit 100 also supplies a developing bias to the developing rollers 52Y, 52M, 52C, and 52K, a primary transfer bias to the intermediate transfer belt 70, and a secondary transfer bias to the secondary transfer roller 82. And stop.

  Further, the control unit 100 causes the display unit 95 to display jam occurrence information indicating that a jam has occurred (step s108), and allows an operator or the like to recognize the occurrence of the jam.

  By the way, when a jam occurs (more specifically, when a jam occurs and the operation of the printer 10 stops), the toner is positioned on the medium S as indicated by ▲ in FIG. 9A. , 20M, 20C, 20K and the intermediate transfer belt 70 also have toner. Specifically, when a jam occurs, as shown by ● in FIG. 9A, residual toner (hereinafter referred to as “photosensitive member”) between the developing unit and the primary transfer unit on the photosensitive members 20Y, 20M, 20C, and 20K. Also referred to as “residual toner D1”). Further, as indicated by ◯ in FIG. 9A, residual toner (on the upstream side in the rotation direction of the intermediate transfer belt 70 as viewed from the secondary transfer portion C1 and between the primary transfer portion B1 and the secondary transfer portion C1). Hereinafter, it is also referred to as “residual toner D2 before second rotation”. Further, as indicated by Δ in FIG. 9A, residual toner (on the downstream side in the rotational direction of the intermediate transfer belt 70 as viewed from the secondary transfer portion C1 and between the secondary transfer portion C1 and the toner removing portion C2). In the following, “non-two-turn residual toner D3”) is located.

  Returning to the flowchart of FIG. 7, the description of the operation of the printer 10 will be continued. When both the opening and closing of the cover 12 are detected by the above-described opening / closing detection sensor after the jam has occurred (step s110: Yes), the control unit 100 detects the medium detection sensors 14a, 14b, 14c, 14d is made to detect whether there is a medium on the medium conveyance path 13 (step s112).

  In the present embodiment, it is assumed that the medium is removed as shown in FIG. 9B between the opening and closing of the cover 12. Then, since the medium detection sensors 14a, 14b, 14c, and 14d do not detect the medium (Step s112: No), the control unit 100 determines that the jammed medium has been removed. That is, the control unit 100 determines that the jam has been resolved (see FIGS. 8 and 10).

  If the control unit 100 determines that the jam has been resolved, the control unit 100 first stops the display of the jam occurrence information on the display unit 95 (step s114). The control unit 100 performs an operation for removing residual toner remaining on the photoreceptors 20Y, 20M, 20C, and 20K and the intermediate transfer belt 70 when a jam occurs (hereinafter, also referred to as “toner removal operation after jam removal”). Execution is started (step s116). By executing this “toner removal operation after jam removal”, the residual toner is removed by the photoconductor cleaning blades 76Y, 76M, 76C, and 76K and the intermediate transfer belt cleaning blade 87. The details of the “toner removal operation after jam removal” will be described later.

  After the execution of the “toner removal operation after clearing jam” is completed, the control unit 100 executes again the formation of the color image that was not formed on the medium due to the occurrence of the jam (step s102). If no jamming of the medium occurs during the color image forming operation (step s104: No), the printer 10 prepares for the next image formation after the color image formation is completed (step s120). .

=== Regarding Toner Removal Operation after Clearing Jam ===
Next, two examples of the toner removal operation after jam clearing will be described. In each of the embodiments, mainly, the operations of the photoconductors 20Y, 20M, 20C, and 20K, the intermediate transfer belt 70, and the voltage supply unit 123 during the toner removal operation after the jam removal, and the photoconductors 20Y and 20M. , 20C, 20K and the state of residual toner on the intermediate transfer belt 70 will be described.

<<<< first embodiment >>
A first embodiment of the toner removal operation after jam clearing will be described with reference to FIGS. 8 and 9A to 9D. FIG. 8 is a time chart for explaining the toner removal operation after jam removal according to the first embodiment. 9A to 9D are schematic diagrams illustrating states of residual toner on the photoreceptors 20Y, 20M, 20C, and 20K and the intermediate transfer belt 70. FIG. 9A shows the state of residual toner when a jam occurs, FIG. 9B shows the state of residual toner at time t1 in FIG. 8, and FIG. 9C shows the state of residual toner at time t2 in FIG. 9D shows the state of the residual toner at time t3 in FIG. In FIG. 8, time t is indicated by an arrow. Further, ◯, ●, Δ, and ▲ shown in FIGS. 9A to 9D indicate toner.

  As described above, when it is determined that the jam has been resolved (at time t1 in FIG. 8), the control unit 100 starts execution of the toner removal operation after the jam is cleared. Specifically, the control unit 100 simultaneously rotates the photoreceptors 20Y, 20M, 20C, and 20K and the intermediate transfer belt 70 at time t1. On the other hand, the control unit 100 does not operate the charging units 30Y, 30M, 30C, and 30K, the exposure units 40Y, 40M, 40C, and 40K, and the developing units 50Y, 50M, 50C, and 50K at time t1. Therefore, no new latent image or toner image is formed on the photoconductors 20Y, 20C, 20M, and 20K (see FIGS. 9C and 9D).

  When the photoreceptors 20Y, 20M, 20C, and 20K rotate at time t1, the photoreceptor residual toner D1 (residual toner indicated by ● in FIG. 9A) that remains on the photoreceptor when a jam occurs also moves. Since the mode of movement of the photoconductor residual toner D1 on each photoconductor is substantially the same, here, the mode of movement of the photoconductor residual toner D1 on the photoconductor 20Y will be described.

  When the photoconductor 20Y rotates, the photoconductor residual toner D1 positioned between the developing unit A1 and the primary transfer unit B1 moves with the rotation of the photoconductor 20Y and is sequentially removed by the photoconductor cleaning blade 76Y. When the jam occurs, the photosensitive member residual toner (hereinafter also referred to as “photosensitive member residual toner D1a”) located in the developing portion A1 moves with the rotation of the photosensitive member 20Y, and at time t2, the photosensitive member It is removed by the cleaning blade 76Y.

  In the toner removal operation after jam removal according to the present embodiment, the control unit 100 does not execute the supply of the primary transfer bias by the primary transfer bias supply unit 123a from the time t1 to the time t2. For this reason, the photosensitive member residual toner D1 reaching the primary transfer portion B1 passes through the primary transfer portion B1 while remaining on the photosensitive member 20Y without moving to the intermediate transfer belt 70.

  The intermediate transfer belt 70 continues to rotate from time t1 to time t2. Accordingly, with this rotation of the intermediate transfer belt 70, residual toner D2 before the second transfer (residual toner indicated by ◯ in FIG. 9A) and non-secondary residual toner D3 (residual toner indicated by Δ in FIG. 9A) Moving. Then, the non-secondary transfer residual toner D3 reaches the toner removing portion C2 as the intermediate transfer belt 70 rotates, and is removed by the intermediate transfer belt cleaning blade 87. On the other hand, the residual toner D2 before the second transfer does not reach the toner removing unit C2 from the time t1 to the time t2.

  The intermediate transfer belt 70 continues to rotate after the time t2, and the intermediate transfer belt cleaning blade 87 moves the non-secondary transfer residual toner D3 that moves with the rotation of the intermediate transfer belt 70 and reaches the toner removing unit C2. Continue to remove. When the jam occurs, the residual toner before secondary transfer located in the secondary transfer portion C1 (hereinafter also referred to as “pre-secondary residual toner D2a”) moves as the intermediate transfer belt 70 rotates, At time t3, the toner removal unit C2 is reached (FIG. 9D).

  The control unit 100 causes the reverse transfer bias supply unit 123b to supply the reverse transfer bias to the intermediate transfer belt 70 when the residual toner D2a before the second transfer reaches the toner removing unit C2 (at time t3). Then, the control unit 100 continues to supply the reverse transfer bias by the reverse transfer bias supply unit 123b until the intermediate transfer belt 70 rotates about once after the occurrence of the jam.

  Then, during the execution of the reverse transfer bias supply by the reverse transfer bias supply unit 123b, all of the residual toner D2 before the second transfer is removed by the intermediate transfer belt cleaning blade 87. Here, the residual toner D2 before the second transfer is the negatively charged toner as described above, and the reverse transfer bias supplied to the intermediate transfer belt 70 has the same polarity as the charged polarity of the residual toner D2 before the second transfer. It is. For this reason, a force for separating the residual toner D2 before the second transfer from the intermediate transfer belt 70 acts on the residual toner D2 before the second transfer located in the toner removing portion C2. Therefore, the residual toner D2 before the second transfer is appropriately removed by the intermediate transfer belt cleaning blade 87.

  In this embodiment, the polarities of the reverse transfer bias and the primary transfer bias are different, but the absolute values of the magnitudes of the biases are the same. Specifically, the magnitude of the primary transfer bias is −250V, and the magnitude of the reverse transfer bias is 250V. However, the magnitudes of the reverse transfer bias and the primary transfer bias are not limited to this, and the absolute value of the magnitude of the reverse transfer bias may be set smaller than the absolute value of the magnitude of the primary transfer bias. For example, the primary transfer bias may be 250V and the reverse transfer bias may be −50V.

  The control unit 100 stops the execution of the reverse transfer bias supply by the reverse transfer bias supply unit 123b at time t4. Further, the control unit 100 stops the rotation of the photoconductors 20Y, 20M, 20C, and 20K and the intermediate transfer belt 70 at time t4. As a result, the toner removal operation after jam removal according to the first embodiment is completed. Here, the time t4 corresponds to the time for which the intermediate transfer belt 70 makes one rotation from the time when the jam occurs. However, the present invention is not limited to this. For example, the time t4 may correspond to the time for which the intermediate transfer belt 70 rotates twice from the time of occurrence of the jam.

<<< second embodiment >>>
A second embodiment of the toner removal operation after jam clearance will be described with reference to FIGS. 9A to 9D and FIG. FIG. 10 is a time chart for explaining the toner removal operation after jam removal according to the second embodiment. Note that the times t1 to t4 shown in FIG. 10 indicate the same times as the times t1 to t4 shown in FIG.

  Also in the second embodiment, the control unit 100 starts execution of the toner removal operation after jam removal at time t1. Then, after the execution of the toner removal operation after the jam removal is started and before the residual toner D2a before the second transfer reaches the toner removal unit C2 (that is, immediately before the time t3), after the jam removal according to the first embodiment. An operation similar to the toner removal operation is performed.

  That is, the photoreceptor residual toner D1 (residual toner indicated by ● in FIG. 9A) on the photoreceptors 20Y, 20M, 20C, and 20K moves with the rotation of the photoreceptor, and the photoreceptor cleaning blades 76Y, 76M, It is removed by 76C and 76K (FIGS. 9B and 9C). Further, the non-second-transfer residual toner D3 on the intermediate transfer belt 70 moves to the toner removing portion C2 as the intermediate transfer belt 70 rotates and is removed by the intermediate transfer belt cleaning blade 87 (FIGS. 9B and 9C). ).

  On the other hand, when the residual toner D2a before the second transfer reaches the toner removing unit C2 (FIG. 9D) and the subsequent operation of the printer 10 are different from the operation of the printer 10 according to the first embodiment. Therefore, in the following, the operation of the printer 10 when the residual toner D2a before the second transfer reaches the toner removing unit C2 and after that will be described.

  Unlike the toner removal operation after jam removal according to the first embodiment, the control unit 100 uses the primary transfer bias supply unit 123a when the residual toner D2a before the second transfer reaches the toner removal unit C2 (at time t3). The supply of the primary transfer bias and the supply of the reverse transfer bias by the reverse transfer bias supply unit 123b are not executed. That is, the voltage supply unit 123 does not supply a voltage to the intermediate transfer belt 70. The voltage supply unit 123 does not supply voltage to the intermediate transfer belt 70 until the intermediate transfer belt 70 rotates about once after the occurrence of a jam.

  Then, all the residual toner D2 before the second transfer is removed by the intermediate transfer belt cleaning blade 87 while the voltage supply by the voltage supply unit 123 is not executed. Here, since the voltage (primary transfer bias) is not supplied from the voltage supply unit 123 to the intermediate transfer belt 70, the residual toner D2 before the second transfer is intermediately added to the residual toner D2 before the second transfer located in the toner removing unit C2. A force that attracts the transfer belt 70 does not act. Therefore, the residual toner D2 before the second transfer is appropriately removed by the intermediate transfer belt cleaning blade 87.

  The control unit 100 stops the photoreceptors 20Y, 20M, 20C, and 20K and the intermediate transfer belt 70 at a time t4 after the residual toner D2 before the second transfer is removed by the intermediate transfer belt cleaning blade 87. As a result, the toner removal operation after jamming is completed.

=== Effectiveness of Printer 10 According to the Present Embodiment ===
As described above, the “image forming apparatus” (printer 10) according to the present embodiment includes (a) the photoreceptors 20Y, 20M, 20C, and 20K that can carry the “developer” (toner), and (b) the A rotatable “intermediate transfer member” (intermediate transfer belt 70) serving as an intermediate medium when transferring the toner of the photosensitive members 20Y, 20M, 20C, and 20K to the medium, and (c) the photosensitive members 20Y, 20M, 20C, and 20K. A voltage supply unit 123 that supplies the intermediate transfer belt 70 with a “transfer voltage” (primary transfer bias) for directing the upper toner to the intermediate transfer belt 70 at the primary transfer units B1, B2, B3, and B4; (D) “secondary transfer member” (secondary transfer roller 82) for transferring the toner moved to the secondary transfer portion C1 with the rotation of the intermediate transfer belt 70 to the medium, and (e) secondary transfer portion C1. View from the intermediate transfer belt A “removal member” (intermediate transfer belt cleaning blade 87) provided on the downstream side in the rotation direction of 0 and contacting the intermediate transfer belt 70 to remove “residual developer” (residual toner) remaining on the intermediate transfer belt 70. ) And (f) a “control unit” (control unit 100) for controlling the voltage supply unit 123. Then, as shown in FIG. 9B, the control unit 100 performs a secondary operation when an event that stops the image forming operation halfway (hereinafter described as an example of a jam of the medium). Residual toner D2 before secondary transfer that is located upstream of the intermediate transfer belt 70 in the rotational direction as viewed from the transfer part C1 and that is located between the primary transfer part (for example, the primary transfer part B1) and the secondary transfer part C1. When the toner is removed by the intermediate transfer belt cleaning blade 87 in order to resume the image forming operation, as shown in FIG. 8 and FIG. The primary transfer bias is not supplied. Accordingly, the residual toner D2 before the second transfer is appropriately removed by the intermediate transfer belt cleaning blade 87 for resuming the image forming operation. This will be described in detail below.

  As described in the section “Problems to be Solved by the Invention”, when a jam occurs, for example, as shown in FIG. 9A, the intermediate transfer belt 70 is located upstream in the rotational direction as viewed from the secondary transfer portion C1. In some cases, residual toner (that is, residual toner D2 before secondary transfer) may be located between the primary transfer portion B1 and the secondary transfer portion C1. In such a case, in order to resume the image forming operation, the residual toner D2 before the second transfer is removed by the intermediate transfer belt cleaning blade 87 after the jam is eliminated. The amount of residual toner to be removed by the transfer belt cleaning blade 87 tends to increase.

  Then, when a large amount of residual toner D2 before the second transfer is removed by the intermediate transfer belt cleaning blade 87 after the jam is eliminated, a primary transfer bias for supplying the toner to the intermediate transfer member is supplied to the intermediate transfer belt 70. As a result, a large amount of residual toner D2 before the second transfer remaining on the intermediate transfer belt 70 is attracted to the intermediate transfer belt 70. In this case, the residual toner D2 before the second transfer may not be properly removed by the intermediate transfer belt cleaning blade 87 and may remain on the intermediate transfer belt 70 as it is.

  This will be specifically described with reference to FIG. 11A. When the primary transfer bias of the intermediate transfer belt 70 is supplied, as shown in FIG. 11A, a force that attracts the residual toner D2 before the second transfer located in the toner removing portion C2 to the intermediate transfer belt 70 (force F1 shown in FIG. 11). But it works. The reason why the force F1 is applied is that the residual toner D2 before the second transfer is a negatively charged toner, and the polarity of the primary transfer bias is opposite to the charged polarity of the residual toner D2 before the second transfer. Therefore, a part of the large amount of residual toner D2 before the second transfer is not removed by the intermediate transfer belt cleaning blade 87 in the toner removing unit C2, and the part passes through the toner removing unit. It becomes. As described above, the toner is not properly removed by the intermediate transfer belt cleaning blade 87. FIG. 11A is a diagram for explaining a comparative example.

  On the other hand, in this embodiment, as shown in FIGS. 8 and 10, the residual toner D2 before the second transfer remaining on the intermediate transfer belt 70 when the medium is jammed is used for resuming the image forming operation. When the intermediate transfer belt cleaning blade 87 removes the primary transfer bias, the voltage supply unit 123 (primary transfer bias supply unit 123a) does not supply the primary transfer bias. Specifically, in the first embodiment shown in FIG. 8, when the residual toner D2 before the second transfer is removed by the intermediate transfer belt cleaning blade 87 to restart the image forming operation, the primary transfer bias is supplied. The primary transfer bias is not supplied by the unit 123a, and the reverse transfer bias is supplied by the reverse transfer bias supply unit 123b. In the second embodiment shown in FIG. 10, when the residual toner D2 before the second transfer is removed by the intermediate transfer belt cleaning blade 87 for resuming the image forming operation, the primary transfer bias supply unit 123a The supply of the primary transfer bias and the supply of the reverse transfer bias by the reverse transfer bias supply unit 123b are not executed.

  As described above, when the primary transfer bias supply unit 123a does not supply the primary transfer bias when the residual toner D2 before the secondary transfer is removed, the residual toner D2 before the secondary transfer located in the toner removal unit C2 is intermediated. The force F1 that attracts the transfer belt 70 does not occur. Therefore, the residual toner D2 before the second transfer is appropriately removed by the intermediate transfer belt cleaning blade 87.

  In the first embodiment shown in FIG. 8, when the residual toner D2 before the second transfer is removed by the intermediate transfer belt cleaning blade 87 after the jam is removed for resuming the image forming operation, the voltage is applied. Since the reverse transfer bias (voltage having the same polarity as the charged polarity of the residual toner D2 before the second transfer) is supplied by the supply unit 123 (reverse transfer bias supply unit 123b), the following effects are produced. That is, when the reverse transfer bias is supplied to the intermediate transfer belt 70, as shown in FIG. 11B, a force F2 that separates the residual toner located in the toner removal unit C2 from the intermediate transfer belt 70 is generated. For this reason, the residual toner is easily removed by the intermediate transfer belt cleaning blade 87. FIG. 11B is a diagram for describing the effectiveness of the printer 10 according to the present embodiment.

=== 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-described embodiment, the photoconductor has been described as a configuration in which a photosensitive layer is provided on the outer peripheral surface of a cylindrical conductive base material. However, the photoconductor is not limited thereto. 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.

  In the above embodiment, the “intermediate transfer member” is a belt. However, the present invention is not limited to this. For example, the “intermediate transfer member” may be a drum. The “removing member” is a blade, but is not limited thereto. For example, the “removing member” may be a roller or the like.

Furthermore, in the above embodiment, as shown in FIGS. 8 and 10, the control unit 100 causes the intermediate transfer belt cleaning blade 87 to perform an event (medium jam) that stops the image forming operation halfway. The “developer removing portion” (toner removing portion C2) where residual toner is removed is located upstream in the rotational direction of the intermediate transfer belt 70, and a primary transfer portion (for example, the primary transfer portion B1). Residual toners (that is, residual toner D2 before the second transfer and non-secondary transfer residual toner D3) located between the toner removal unit C2 are removed by the intermediate transfer belt cleaning blade 87 to restart the image forming operation. At this time, the supply of the primary transfer bias by the voltage supply unit 123 is not executed, but the present invention is not limited to this. For example, when the residual toner D2 before the second transfer is removed, the supply of the primary transfer bias is not executed by the voltage supply unit 123, and when the non-secondary transfer residual toner D3 is removed, the voltage supply unit 123 The primary transfer bias may be supplied.
As described above, when a jam occurs, the non-secondary transfer residual toner D3 remaining on the intermediate transfer belt 70 without being secondarily transferred to the medium in the secondary transfer portion C1 before the jam occurs It is located between the next transfer portion C1 and the toner removal portion C2 (FIG. 9A). In this case, assuming that the supply of the primary transfer bias by the voltage supply unit 123 is not executed even when the non-secondary transfer residual toner D3 is removed, not only the residual toner D2 but also the non-secondary transfer residual toner D3. Thus, the intermediate transfer belt cleaning blade 87 appropriately removes it. Therefore, the above embodiment is more desirable.

Further, in the above-described embodiment, the voltage supply unit 123 (primary transfer bias supply unit 123a) supplies the primary transfer bias over the entire intermediate transfer belt 70, but is not limited thereto. For example, the intermediate transfer belt 70 is an annular belt having a joint portion having a constant width along the belt orthogonal direction (FIG. 5), and the primary transfer bias supply unit 123a performs primary transfer to the joint portion of the intermediate transfer belt 70. The bias may not be supplied (that is, the primary transfer bias supply unit 123a does not supply the primary transfer bias to the entire intermediate transfer belt 70).
However, when the primary transfer bias is supplied to the entire intermediate transfer belt 70, the residual toner D2 before the second transfer located in the toner removing portion C2 when the primary transfer bias is supplied to the intermediate transfer belt 70. The force that attracts the intermediate transfer belt 70 to the intermediate transfer belt 70 (force F1 shown in FIG. 11A) is constantly generated. Therefore, the effect of not supplying the primary transfer bias when the residual toner D2 before the second transfer is removed, that is, the residual toner D2 before the second transfer by the intermediate transfer belt cleaning blade 87 for restarting the image forming operation. The effect that the removal is appropriately performed is more effectively achieved. Therefore, the above embodiment is more desirable.

  Furthermore, in the above embodiment, as shown in FIG. 6, the electrode layer 70b is provided at the end of the intermediate transfer belt 70 in the orthogonal direction orthogonal to the rotation direction of the intermediate transfer belt 70. . Further, the printer 10 is provided with a “conductive member” (electrode roller 210) that comes into contact with the electrode layer 70b. The voltage supply unit 123 supplies the primary transfer bias to the intermediate transfer belt 70 via the electrode roller 210. However, the configuration is not limited to the above, and any configuration may be used as long as the primary transfer bias can be supplied from the voltage supply unit 123 to the intermediate transfer belt 70.

Further, in the above embodiment, as shown in FIG. 1, the printer 10 has four photoconductors 20Y and 20M that can carry toners having different colors (that is, yellow toner, magenta toner, cyan toner, and black toner). , 20C, 20K. The intermediate transfer belt 70 serves as an intermediate medium when transferring the toner on each of the photoreceptors 20Y, 20M, 20C, and 20K to the medium. However, it is not limited to the above. For example, the printer 10 may include only one photoconductor (for example, the photoconductor 20K) in order to form a monochrome image.
However, when the printer 10 includes four photoconductors 20Y, 20M, 20C, and 20K, the toner on the photoconductor is sequentially transferred to the intermediate transfer belt 70 at the primary transfer portions B1, B2, B3, and B4. Therefore, the residual toner D2 before the second transfer remaining on the intermediate transfer belt 70 when the jam occurs tends to increase more. Therefore, the effect of not supplying the primary transfer bias when the residual toner D2 before the second transfer is removed, that is, the residual toner D2 before the second transfer by the intermediate transfer belt cleaning blade 87 for restarting the image forming operation. The effect that the removal is appropriately performed is more effectively achieved. Therefore, the above embodiment is more desirable.

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

  FIG. 12 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. 13 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 illustrating a configuration of a control unit 100 of the printer 10. FIG. It is the figure which showed the image formation part 15Y. 2 is a diagram illustrating an intermediate transfer belt 70 and the like. FIG. 3 is a schematic diagram showing a part of the outer peripheral surface of the intermediate transfer belt 70. FIG. FIG. 4 is a diagram illustrating a contact state between an intermediate transfer belt and a primary transfer unit. 6 is a flowchart for explaining the operation of the printer when a jam occurs during image formation. 6 is a time chart for explaining a toner removal operation after jam removal according to the first embodiment. It shows the state of residual toner when a jam occurs. The state of the residual toner at time t1 in FIG. 8 is shown. The state of residual toner at time t2 in FIG. 8 is shown. The state of residual toner at time t3 in FIG. 8 is shown. It is a time chart for demonstrating the toner removal operation | movement after jam clearance which concerns on 2nd Example. FIG. 11A is a diagram for explaining a comparative example. FIG. 11B is a diagram for describing the effectiveness of the printer 10 according to the present embodiment. 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, 12 cover, 13 medium transport path,
14a, 14b, 14c, 14d Medium detection sensor,
15Y, 15M, 15C, 15K image forming unit,
20Y, 20M, 20C, 20K photoreceptor,
30Y, 30M, 30C, 30K charging unit,
31Y, 31M, 31C, 31K charging roller,
35Y, 35M, 35C, 35K cleaning rollers,
40Y, 40M, 40C, 40K exposure unit,
50Y, 50M, 50C, 50K development unit,
51Y, 51M, 51C, 51K toner container,
52Y, 52M, 52C, 52K developing roller,
53Y, 53M, 53C, 53K supply roller,
60 Primary transfer unit, 65Y, 65M, 65C, 65K Backup roller,
70 intermediate transfer belt, 71a driving roller, 71b driven roller,
71c roller, 71d roller,
75Y, 75M, 75C, 75K photoconductor cleaning unit,
76Y, 76M, 76C, 76K photoconductor cleaning blade,
80 secondary transfer unit, 82 secondary transfer roller,
85 Intermediate transfer belt cleaning unit, 86 container,
87 Intermediate transfer belt cleaning blade, 90 fixing unit,
90a fixing roller, 90b pressure roller, 92 paper feed tray,
94a paper feed roller, 94b registration roller, 94c paper discharge roller,
95 display unit, 98 paper output tray,
100 control unit, 101 main controller,
102 unit controller, 112 interface, 113 image memory,
121 charging bias supply unit, 122 developing bias supply unit, 123 voltage supply unit,
123a primary transfer bias supply unit, 123b reverse transfer bias supply unit,
124 secondary transfer bias supply unit,
210 electrode roller, 211 contact portion, 212 roller shaft, 220 roller bearing,
230 roller support sheet metal,
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, 802 internal memory,
A1, A2, A3, A4 Development part, B1, B2, B3, B4 Primary transfer part,
C1 secondary transfer unit, C2 toner removal unit

Claims (8)

(A) a photoreceptor capable of carrying a developer;
(B) a rotatable intermediate transfer member serving as an intermediate medium when transferring the developer on the photosensitive member to the medium;
(C) a voltage supply unit that supplies the intermediate transfer member with a transfer voltage for directing the developer on the photosensitive member to the intermediate transfer member at a primary transfer unit;
(D) a secondary transfer member for transferring the developer that has moved to the secondary transfer portion with the rotation of the intermediate transfer member to a medium;
(E) a removing member that is provided on the downstream side in the rotational direction of the intermediate transfer member as viewed from the secondary transfer unit, contacts the intermediate transfer member, and removes residual developer remaining on the intermediate transfer member;
An image forming apparatus comprising (f),
(G) a control unit for controlling the voltage supply unit,
When an event for stopping the image forming operation occurs halfway, it is located upstream in the rotation direction of the intermediate transfer member as viewed from the secondary transfer unit, and the primary transfer unit and the secondary transfer unit Residual developer located between,
When the removal member is removed for resuming the image forming operation, the control unit that does not execute the supply of the transfer voltage by the voltage supply unit,
An image forming apparatus comprising: The image forming apparatus according to claim 1,
The voltage supply unit
In addition to supplying the transfer voltage for directing the developer to the intermediate transfer member to the intermediate transfer member, a reverse transfer voltage for separating the developer from the intermediate transfer member is also supplied to the intermediate transfer member. Is possible,
The controller is
When an event for stopping the image forming operation occurs halfway, it is located upstream in the rotation direction of the intermediate transfer member as viewed from the secondary transfer unit, and the primary transfer unit and the secondary transfer unit Residual developer located between,
When the removal member is removed for resuming the image forming operation, the reverse supply voltage is supplied by the voltage supply unit. The image forming apparatus according to claim 1, wherein:
The controller is
When an event for stopping the image forming operation occurs in the middle, the developer is removed upstream of the intermediate transfer member when viewed from the developer removing portion where residual developer is removed by the removing member, and A residual developer positioned between the primary transfer portion and the developer removing portion;
The image forming apparatus is characterized in that supply of the transfer voltage by the voltage supply unit is not executed when the removal member is removed by the removal member for resuming the image forming operation. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus, wherein the voltage supply unit supplies the transfer voltage over the entire intermediate transfer member. The image forming apparatus according to claim 4,
An electrode layer is provided at an end of the intermediate transfer member perpendicular to the rotation direction of the intermediate transfer member,
A conductive member in contact with the electrode layer;
The image forming apparatus, wherein the voltage supply unit supplies the transfer voltage to the intermediate transfer member via the conductive member. An image forming apparatus according to any one of claims 1 to 5,
Comprising the four photoconductors capable of carrying developers of different colors,
The image forming apparatus, wherein the intermediate transfer member serves as an intermediate medium when transferring the developer on each of the photosensitive members to the medium. (A) a photoreceptor capable of carrying a developer;
(B) a rotatable intermediate transfer member serving as an intermediate medium when transferring the developer on the photosensitive member to the medium;
(C) a voltage supply unit for supplying the intermediate transfer member with a transfer voltage for directing the developer on the photosensitive member to the intermediate transfer member at a primary transfer unit;
(D) a secondary transfer member for transferring the developer that has moved to the secondary transfer portion with the rotation of the intermediate transfer member to a medium;
(E) a removing member that is provided on the downstream side in the rotational direction of the intermediate transfer member as viewed from the secondary transfer unit, contacts the intermediate transfer member, and removes residual developer remaining on the intermediate transfer member;
An image forming apparatus comprising (f),
(G) a control unit for controlling the voltage supply unit,
When an event for stopping the image forming operation occurs halfway, it is located upstream in the rotation direction of the intermediate transfer member as viewed from the secondary transfer unit, and the primary transfer unit and the secondary transfer unit Residual developer located between,
When the removal member is removed for restarting the image forming operation, a control unit that does not execute the supply of the transfer voltage by the voltage supply unit,
With
(H) The voltage supply unit includes:
In addition to supplying the transfer voltage for directing the developer to the intermediate transfer member to the intermediate transfer member, a reverse transfer voltage for separating the developer from the intermediate transfer member is also supplied to the intermediate transfer member. Is possible,
The controller is
When an event for stopping the image forming operation occurs halfway, it is located upstream in the rotation direction of the intermediate transfer member as viewed from the secondary transfer unit, and the primary transfer unit and the secondary transfer unit Residual developer located between,
Is removed by the removal member to resume the image forming operation, the supply of the reverse transfer voltage by the voltage supply unit is executed,
(I) The control unit
When an event for stopping the image forming operation occurs in the middle, the developer is removed upstream of the intermediate transfer member when viewed from the developer removing portion where residual developer is removed by the removing member, and A residual developer positioned between the primary transfer portion and the developer removing portion;
Is removed by the removal member for resuming the image forming operation, the supply of the transfer voltage by the voltage supply unit is not executed,
(J) The voltage supply unit supplies the transfer voltage over the entire intermediate transfer member,
(K) An electrode layer is provided at the end of the intermediate transfer member in the orthogonal direction orthogonal to the rotation direction of the intermediate transfer member;
A conductive member in contact with the electrode layer;
The voltage supply unit supplies the transfer voltage to the intermediate transfer member via the conductive member;
(L) the four photoconductors capable of carrying developers of different colors from each other,
The image forming apparatus, wherein the intermediate transfer member serves as an intermediate medium when transferring the developer on each of the photosensitive members to the medium. (A) a computer, and
(B) An image forming apparatus connectable to the computer,
(A) a photoreceptor capable of carrying a developer;
(B) a rotatable intermediate transfer member serving as an intermediate medium when transferring the developer on the photosensitive member to the medium;
(C) a voltage supply unit for supplying the intermediate transfer member with a transfer voltage for directing the developer on the photosensitive member to the intermediate transfer member at a primary transfer unit;
(D) a secondary transfer member for transferring the developer that has moved to the secondary transfer portion with the rotation of the intermediate transfer member to a medium;
(E) a removing member that is provided on the downstream side in the rotational direction of the intermediate transfer member as viewed from the secondary transfer unit, contacts the intermediate transfer member, and removes residual developer remaining on the intermediate transfer member;
An image forming apparatus comprising (f),
(G) a control unit for controlling the voltage supply unit,
When an event for stopping the image forming operation occurs halfway, it is located upstream in the rotation direction of the intermediate transfer member as viewed from the secondary transfer unit, and the primary transfer unit and the secondary transfer unit Residual developer located between,
When the removal member is removed for restarting the image forming operation, a control unit that does not execute the supply of the transfer voltage by the voltage supply unit,
An image forming apparatus comprising:
An image forming system comprising (C).

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