JP2010262063A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading device in which the transfer pressure and contact width of the photoreceptor drums of respective image forming units and intermediate transfer rollers can be set so as to be identical, and in which the image forming units can be surely brought into contact with and separated from an intermediate transfer belt. <P>SOLUTION: An image forming apparatus 1 includes: the plurality of image forming units 20 to 23 which form toner images different in color on the surfaces of the photoreceptor drums; the intermediate transfer belt 30 which is stretched between a driving roller 31 and a driven roller 33, and to which the toner images formed on the photoreceptor drums are transferred; and a support frame 36 to which the driving roller 31, the driven rollers 32 and 33 and the intermediate transfer rollers are attached. The support frame 36 is attached so as to be rotatable around the rotating shaft of the driving roller 31, and a driving member 70 provided in the support frame 36 is moved up and down, so that the intermediate transfer belt 30 is brought into contact with and separated from the photoreceptor drums. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  In the above-described image forming apparatus, an electrostatic latent image is formed on the surface of the photosensitive drum and visualized with toner, the formed toner image is transferred to a sheet to form an image, and the toner transferred to the sheet An electrophotographic method for fixing an image on paper is employed.

  When forming a color image in an electrophotographic image forming apparatus, the toner image is repeatedly formed on a sheet wound from a plurality of image forming units that wrap a sheet around a transfer drum and form toner images of different colors on the surface of the photosensitive drum. There is a transfer method (transfer drum method). In addition, a system such as a system (intermediate transfer system) in which a toner image is temporarily transferred from a plurality of image forming units to an intermediate transfer belt to form a color toner image, and the formed color toner image is transferred to a sheet. Has been proposed.

  The intermediate transfer type image forming apparatus includes a black toner image forming unit for recording a monochrome image and a plurality of color toner image forming units for recording a color image. When a monochrome image is recorded, the color toner image forming portion is separated from the intermediate transfer belt.

  For example, Patent Document 1 describes an image forming apparatus in which a monochrome image forming unit is fixed to a main body frame, and a color image forming unit is fixed to a subframe different from the main body frame. The sub-frame is attached so that the photosensitive drum of the color image forming means can be moved to a contact position or a separation position with the transfer conveyance belt. Patent Document 2 describes an image forming apparatus in which a transfer roller is rotated from a photosensitive drum by rotating a driving roller and a driven roller that stretch the transfer belt. Patent Document 3 describes an image forming apparatus in which the color photosensitive drum is separated from the transfer belt by tilting the transfer unit with the rolling contact portion between the black photosensitive drum and the transfer belt as a fulcrum. Has been. Further, Patent Document 4 describes an image forming apparatus in which, when an image is formed only on an upstream image forming station in the transfer belt conveyance direction, the downstream transfer belt is inclined downward to be separated from the image forming station. Yes. In Patent Document 5, the transfer belt is provided so as to be able to swing around the rotation axis of the transfer roller of the image forming unit, and the transfer belt is set in a horizontal position in the color image forming mode and is inclined in the single color image forming mode. An image forming apparatus set to a position is described. ,

JP-A-8-328395 JP 2001-034082 A JP 2001-100480 A JP 2002-304036 A JP 2003-091125 A

  In the case of an intermediate transfer type image forming apparatus as shown in Patent Document 1, it is common that the transfer pressure for bringing the intermediate transfer roller into contact with each photosensitive drum is the same and set to a low load. However, since the tension of the intermediate transfer belt is larger in the photosensitive drum arranged near the conveying roller that stretches the intermediate transfer belt than in the case where the intermediate transfer belt is arranged far away, the transfer pressure is low. May cause poor contact between the photosensitive drum and the intermediate transfer roller.

  In addition, when the image forming unit for forming the color toner image is integrally rotated and brought into contact with and separated from the intermediate transfer belt, the separation distance of the intermediate transfer belt from the photosensitive drum of the image forming unit is different. Therefore, it is necessary to widen the interval between the other photosensitive drums in accordance with the narrowed photosensitive drum. In this case, there is a problem that it is difficult to set the transfer pressure for all the photosensitive drums to be the same due to the influence of the assembly accuracy of the rotation mechanism.

  Further, a method is also considered in which the intermediate transfer belt is brought into contact with and separated from the photosensitive drum by integrally rotating the intermediate transfer roller side. In this case, in order to make the intermediate transfer belt easily contacted and separated, the conveying roller is often set at a position previously separated from the photosensitive drum, which is not preferable because the contact width between the photosensitive drum and the intermediate transfer roller is reduced. .

  Therefore, according to the present invention, the transfer pressure and contact width of the photosensitive drum and the intermediate transfer roller of each image forming unit can be set to be the same, and the image forming unit can be reliably brought into and out of contact with the intermediate transfer belt. An object of the present invention is to provide a possible image reading apparatus.

  An image reading apparatus according to the present invention is arranged in close proximity to a plurality of image forming units that form toner images of different colors on the surface of a photosensitive drum, and a driving roller and a driven roller. And an intermediate transfer belt to which a toner image formed on the photosensitive drum is transferred, a plurality of intermediate transfer rollers arranged to face each of the photosensitive drums via the intermediate transfer belt, and the intermediate transfer An image forming apparatus including a transfer unit configured to transfer a toner image composed of a plurality of colors transferred to a belt to a sheet, wherein the driving roller, the driven roller, and the intermediate transfer roller have a plane in contact with any of them. It is attached to the support frame as set, and the plane is arranged so as to be parallel to a reference plane in contact with all the photosensitive drums. Cage, characterized in that it comprises a moving mechanism for the support frame is rotated around the rotating shaft of the driving roller of the intermediate transfer belt the photosensitive drum in contact away with. Further, the contact / separation mechanism makes the contact / separation operation of the photosensitive drum of the image forming unit other than the image forming unit for forming a black toner image. Further, the contact / separation mechanism is driven by a power source that drives the intermediate transfer belt.

  With the above-described configuration, the driving roller, the driven roller, and the intermediate transfer roller are attached to the support frame so that the plane in contact with all of them is parallel to the reference plane in contact with all the photosensitive drums. . Therefore, the intermediate transfer roller can be set to apply the same transfer pressure with the same contact width to the photosensitive drum.

  In addition, since the support frame is provided with a contact / separation mechanism that rotates the support frame around the rotation axis of the drive roller to contact and separate the intermediate transfer belt from the photosensitive drum, the drive roller, the driven roller, and the intermediate transfer accompanying the rotation operation are provided. It can suppress that the precision of the positional relationship of a roller falls. For this reason, even if the contact movement is performed so that the space between the photosensitive drum and the intermediate transfer belt is sufficiently separated from each other, the positional accuracy of the intermediate transfer roller with respect to the photosensitive drum is maintained, and stable contact and separation are maintained. The action can be performed.

It is a schematic block diagram regarding embodiment which concerns on this invention. FIG. 4 is an explanatory diagram relating to an arrangement relationship among a photosensitive drum, an intermediate transfer roller, a driving roller, and a driven roller. FIG. 4 is a schematic configuration diagram relating to a contact / separation mechanism for driving a drive member to contact and separate a photosensitive drum from an intermediate transfer belt. FIG. 6 is an operation explanatory diagram when the intermediate transfer belt is separated from the photosensitive drum. FIG. 6 is an operation explanatory diagram when the intermediate transfer belt is set from the separated state to the contact state with respect to the photosensitive drum.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 is a schematic configuration diagram relating to an embodiment of the present invention. The image forming apparatus 1 includes an image forming unit 2, an intermediate transfer unit 3, a transfer unit 4, and a paper feeding unit 5 in a housing.

  The image forming unit 2 includes a plurality of image forming units 20 to 23 that form toner images of different colors on the surface of the photosensitive drum. The image forming unit 20 is an image forming unit that forms a black toner image, and includes a developing device 201, a charging roller 202, an exposure head 203, a photosensitive drum 204, and a memory removal brush 205.

  In the image forming unit 20, first, the surface of the photosensitive drum 204 is uniformly charged by the charging roller 202, and the charged surface of the photosensitive drum 204 is exposed by the exposure head (LED head) 203 according to the image recording signal. As a result, an electrostatic latent image is formed. Next, the toner in the developing unit 201 is transferred to an electrostatic latent image formed on the photosensitive drum 204 by a supply roller and a developing roller to be visualized, and is transferred onto the surface of the photosensitive drum 204 by an intermediate transfer roller 350 described later. The formed toner image is transferred to an intermediate transfer belt 30 described later.

  In this way, a series of processes such as charging, exposure, development, and transfer to the photosensitive drum 204 is performed, and a black toner image is formed and transferred to the intermediate transfer belt. The toner remaining on the surface of the photosensitive drum 204 after the transfer is weakened in adhesion by a memory removal brush (ERS brush) 205 and dispersed on the surface of the photosensitive drum 204. The residual toner is collected on the developing roller of the developing device 201.

  Note that toner remaining on the surface of the photosensitive drum 204 after the toner image is transferred may be removed by placing the cleaning blade close to the photosensitive drum 204 and using the cleaning blade.

  The image forming units 21 to 23 are used for forming a toner image for forming a color image. The image forming unit 21 is an image forming unit that forms a yellow toner image on the surface of the photosensitive drum. Similar to the image forming unit 20, the image forming unit 21 includes a developing device 211, a charging roller 212, an exposure head 213, a photosensitive drum 214, and a memory removal brush 215. Similarly to the image forming unit 20, a series of processes such as charging, exposure, development, and transfer to the photosensitive drum 214 is performed, and a yellow toner image is formed and transferred to the intermediate transfer belt 30.

  The image forming unit 22 is an image forming unit that forms a magenta toner image on the surface of the photosensitive drum. Similar to the image forming unit 20, the image forming unit 22 includes a developing device 221, a charging roller 222, an exposure head 223, a photosensitive drum 224, and a memory removal brush 225. As in the image forming unit 20, a series of processes such as charging, exposure, development, and transfer to the photosensitive drum 224 are performed, and a magenta toner image is formed and transferred to the intermediate transfer belt 30.

  The image forming unit 23 is an image forming unit that forms a cyan toner image on the surface of the photosensitive drum. Similar to the image forming unit 20, the image forming unit 23 includes a developing device 231, a charging roller 232, an exposure head 233, a photosensitive drum 234, and a memory removal brush 235. As in the image forming unit 20, a series of processes such as charging, exposure, development, and transfer to the photosensitive drum 234 are performed, and a cyan toner image is formed and transferred to the intermediate transfer belt 30.

  The image forming units 20 to 23 are arranged in the horizontal direction, and the photosensitive drums 204 to 234 are partially exposed downward on the lower surface. The reference plane S in contact with the lower end of each photosensitive drum is set along the horizontal direction as shown in FIG.

  The intermediate transfer unit 3 includes an endless intermediate transfer belt 30 and intermediate transfer rollers 350 to 353. The intermediate transfer belt 30 is stretched by a drive roller 31, driven rollers 32 and 33, and a support roller 34, and is rotated and driven by the drive roller 31 being rotated.

  Inside the intermediate transfer belt 30 that is stretched, intermediate transfer rollers 350 to 353 are arranged on the lower surface side of the intermediate transfer belt 30 so as to face the photosensitive drums 204 to 234, respectively.

  The drive roller 31, the driven rollers 32 and 33, the support roller 34, and the intermediate transfer rollers 350 to 353 are attached to the support frame 36. One end of the support frame 36 is rotatably attached to a rotation shaft provided in the apparatus main body so as to be coaxial with the rotation shaft of the drive roller 31. A stopper (not shown) is provided at the other end of the support frame 36, and a regulating member provided in the apparatus main body when the other end of the support frame 36 is rotated downward by a predetermined angle. It comes to contact with.

  As shown in FIG. 2, the driving roller 31, the driven roller 33, and the intermediate transfer rollers 350 to 353 are arranged on the support frame 36 so that a plane T that is in contact with the upper ends of all these rollers is set. Then, in a state where the support frame 36 is rotated and the horizontal direction is set so that the plane T is parallel to the reference plane S, all the photosensitive drums 204 to 234 are in contact with the intermediate transfer belt.

  In a state where the plane T is set in the horizontal direction, the plane T is positioned so as to be shifted slightly upward from the reference plane S. Therefore, the intermediate transfer rollers 350 to 353 are set so as to contact the photosensitive drum at a position slightly shifted from the lower end position (position where the reference plane S contacts) to the downstream side in the conveyance direction of the intermediate transfer belt. Thus, by shifting the contact position of the intermediate transfer roller with respect to the photosensitive drum to the downstream side in the transport direction, the contact width of the photosensitive drum with respect to the intermediate transfer belt can be widened to maintain a stable contact state.

  In this case, since the plane T is set to be parallel to the reference plane S, each intermediate transfer roller contacts with each photoconductor drum so as to have the same transfer pressure with the same contact width. It becomes like this. Therefore, it is possible to prevent a transfer failure due to a poor pressure contact of the intermediate transfer roller.

  The intermediate transfer rollers 350 to 353 are raised to the operating position by an elastic member or the like, so that the intermediate transfer rollers 350 to 353 push up the lower surface of the intermediate transfer belt 30 and are respectively passed to the photosensitive drums 204 to 234 via the intermediate transfer belt 30. It comes in pressure contact. A transfer voltage is applied to each intermediate transfer roller from a voltage application circuit (not shown), and the intermediate transfer belt 30 is conveyed in synchronism with the rotation speed of each photoconductor drum to be formed on the surface of each photoconductor drum. The toner image is transferred onto the surface of the intermediate transfer belt 30.

  The paper feed unit 5 feeds the paper in the paper feed cassette 50 one by one by a paper feed roller 51. The fed paper is sandwiched between the transport roller 60 and the press roller 61 and transported to the transfer unit 4. In the transfer unit 4, a transfer roller 40 is disposed to face the support roller 34, and a predetermined transfer voltage is applied to the transfer roller 40 by a voltage application circuit (not shown). The conveyed paper is conveyed while being sandwiched between the transfer roller 40 and the intermediate transfer belt 30, and the toner image carried on the intermediate transfer belt 30 is transferred to the paper during that time.

  The sheet on which the toner image has been transferred is sandwiched between the fixing roller 62 and the press roller 63 and subjected to a fixing process, and the sheet on which the toner image has been fixed is sandwiched between the discharge roller 64 and the press roller 65 and discharged. Paper is ejected to the tray.

  A rod-shaped drive member 70 is attached to the support frame 36. The drive member 70 is disposed along the vertical direction, and its upper end is rotatably attached to the bottom of the support frame 36. The lower end of the drive member 70 is attached to a guide member (not shown) provided in the apparatus main body so as to be movable up and down. Therefore, by moving the drive member 70 up and down, the support frame 36 rotates about a rotation axis that is coaxial with the rotation axis of the drive roller 31. When the support frame 36 is rotated downward, the photosensitive drums 214 to 234 of the image forming units 21 to 23 with respect to the intermediate transfer belt 30 in a state where the photosensitive drum 204 of the image forming unit 20 is in contact with the intermediate transfer belt 30. The rotation angle is set in advance so as to be separated from each other. With this setting, the photosensitive drums 214 to 234 can be moved toward and away from the intermediate transfer belt 30 by reciprocating the drive member 70 in the vertical direction.

  FIG. 3 is a schematic configuration diagram relating to a contact / separation mechanism for driving the drive member 70 to contact and separate the photosensitive drum from the intermediate transfer belt. In this example, the drive member 70 is driven by a drive motor 80 which is a drive source for carrying the intermediate transfer belt 30. Between the drive motor 80 and the drive roller 31, a gear train 81 for transmitting the rotational drive of the drive motor 80 is provided, and an electromagnetic clutch 82 is attached to one of the gear trains.

  A rack tooth row (not shown) is formed at one end portion of the drive member 70, and a gear train 71 that meshes with the rack tooth row is provided. The gear train 71 is engaged with a gear provided with an electromagnetic clutch 73 via a transmission gear 72, and the gear train 81 provided with the electromagnetic clutch 73 is rotated by a drive motor 80 via a transmission gear 76. Is engaged with the transmission gear 83. The transmission gear 72 is engaged with a gear provided with an electromagnetic clutch 75 via a transmission gear 74, and the gear provided with the electromagnetic clutch 75 is engaged with a transmission gear 76.

  The electromagnetic clutches 73 and 75 are driven and controlled so that either one is connected and the other is disconnected. Therefore, for example, when the electromagnetic clutch 73 is connected, the gear train 71 rotates in a predetermined direction to transmit drive, and the drive member 70 is driven to move downward. On the other hand, when the electromagnetic clutch 75 is connected, the transmission gear 74 is provided, so that the gear train 71 rotates in the opposite direction to that of the electromagnetic clutch 73 to perform drive transmission, and the drive member 70. Is driven to move upward. Thus, by alternately connecting the electromagnetic clutches 73 and 75, the drive member 70 can be reciprocated in the vertical direction.

  In FIG. 3, the electromagnetic clutches 73 and 75 are disconnected and the electromagnetic clutch 82 is connected, and the rotational drive of the drive motor 80 is transmitted to the drive roller 31 so that the intermediate transfer belt 30 is conveyed. A recording operation is performed.

  FIG. 4 is an operation explanatory diagram regarding the driving member 70 when the intermediate transfer belt is separated from the photosensitive drum. In a state where the recording operation is stopped, the electromagnetic clutch 82 is disconnected and the conveyance of the intermediate transfer belt 30 is stopped. And the electromagnetic clutch 73 is connected, the electromagnetic clutch 75 is cut | disconnected, and the rotational drive of the drive motor 80 is transmitted to the drive member 70 side. In this case, the drive member 70 operates so as to move downward, rotate the support frame 36 downward by a predetermined angle, and move the photosensitive drums 214 to 234 away from the intermediate transfer belt 30. When the support frame 36 is rotated by a predetermined angle, the stopper of the support frame 36 is brought into contact with a regulating member provided in the apparatus main body so that the support frame 36 does not rotate more than a predetermined angle.

  In this way, the electromagnetic clutch 73 is disconnected while the photosensitive drums 214 to 234 are separated from the intermediate transfer belt 30, and the electromagnetic clutch 82 is connected to carry the intermediate transfer belt 30. Only the image forming unit 20 that forms a black toner image is in contact with the intermediate transfer belt 30, and an image forming process in a monochrome mode can be performed.

  Further, since the support frame 36 rotates about the rotation axis of the driving roller 31, it can rotate while maintaining the positional relationship among the driving roller 31, the driven roller 33, and the intermediate transfer rollers 350 to 353. Therefore, the image forming units 21 to 23 for forming color toner images can be sufficiently separated from the photosensitive drums 204 to 234 with respect to the intermediate transfer belt 30, and the image forming units 21 to 23 can be separated. Thus, the influence of inadvertent contact with the intermediate transfer belt 30 can be reliably prevented.

  FIG. 5 is an operation explanatory diagram regarding the driving member 70 when the intermediate transfer belt is set from the separated state to the contact state with respect to the photosensitive drum. In a state where the recording operation is stopped, the electromagnetic clutch 82 is disconnected and the conveyance of the intermediate transfer belt 30 is stopped. And the electromagnetic clutch 75 is connected, the electromagnetic clutch 73 is cut | disconnected, and the rotational drive of the drive motor 80 is transmitted to the drive member 70 side.

  In this case, the driving member 70 operates to move upward to rotate the support frame 36 and move the photosensitive drums 214 to 234 in a direction in contact with the intermediate transfer belt 30. Then, the plane T in contact with the driving roller 31, the driven roller 33 and the intermediate transfer rollers 350 to 353 attached to the support frame 36 is set to a state in which they coincide with each other in the horizontal direction. Whether or not the position is set in the horizontal direction may be determined by, for example, providing a sensor for detecting the rotation operation of the support frame 36 and detecting the horizontal position. Alternatively, the horizontal position may be set when the rotational speed of the drive motor 80 is counted and rotated by a predetermined rotational speed. In this way, all the image forming units are in contact with the intermediate transfer belt 30, and color mode image forming processing can be performed.

  As described above, since the support frame 36 is rotated about the rotation axis of the drive roller, the drive roller 31, the driven roller 33, and the intermediate transfer rollers 350 to 353 can be rotated while maintaining the positional accuracy. it can. Therefore, when setting the plane in contact with the intermediate transfer roller to be parallel to the reference plane in contact with the photosensitive drums 204 to 234, each intermediate transfer roller can be accurately positioned with respect to each photosensitive drum. It becomes possible.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming part 3 Intermediate transfer part 4 Transfer part 5 Paper feed part
20-23 Image forming unit
30 Intermediate transfer belt
350 to 353 Intermediate transfer roller
70 Drive member

Claims (3)

  A plurality of image forming units that form toner images of different colors on the surface of the photosensitive drum, and are arranged in proximity to the photosensitive drum while being stretched by a driving roller and a driven roller, and formed on the photosensitive drum. An intermediate transfer belt to which a toner image is transferred, a plurality of intermediate transfer rollers arranged to face each of the photosensitive drums via the intermediate transfer belt, and a plurality of colors transferred to the intermediate transfer belt. An image forming apparatus including a transfer unit that transfers a toner image onto a sheet, wherein the driving roller, the driven roller, and the intermediate transfer roller are attached to a support frame so that a plane in contact therewith is set. And arranged so that the plane is parallel to a reference plane in contact with all of the photosensitive drums, Image forming apparatus characterized by is rotated around the rotation shaft of the drive roller and a separation mechanism for contacting and separating the intermediate transfer belt to the photoconductive drum.   The image forming apparatus according to claim 1, wherein the contact / separation mechanism causes the photosensitive drum of the image forming unit other than the image forming unit that forms a black toner image to contact and separate.   The image forming apparatus according to claim 1, wherein the contact / separation mechanism is driven by a power source that drives the intermediate transfer belt.

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