JP2012185453A - Transfer device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer device and an image forming apparatus capable of suppressing transfer failure of a toner image when the toner image formed on an image holder is transferred to a recording medium by use of a discharge electrode.SOLUTION: When a transfer blade 64 moves to a pressing position, an image holder belt 16 is pressed to distort by the transfer blade 64, which produces a curved line state in a side view of a conveyance route of a sheet member P to be conveyed and allows changes in the conveyance direction of the sheet member P. Thereby, a force stretching the sheet member P in a width direction acts to stretch wrinkles produced in the sheet member P. Thereby, transfer failure (void) is suppressed when a toner image is transferred to the sheet member P.

Description

  The present invention relates to a transfer device and an image forming apparatus.

  The tip of the transfer assist blade used in the transfer device described in Patent Document 1 has an arc shape whose center swells with respect to the traveling direction of the recording sheet.

JP 2006-267482 A

  An object of the present invention is to suppress toner image transfer failure when a toner image formed on an image carrier is transferred to a recording medium using a discharge electrode.

  The transfer device according to claim 1 of the present invention is a first regulating member that regulates a circulation path of the circulating image holding member that hits the back surface of the endless image holding member that rotates while holding the toner image on the surface; A sheet-like shape that discharges toward the image carrier whose circulation path is regulated by the first regulating member, and that conveys the toner image held on the image carrier in a discharge region while overlapping the surface of the image carrier. A transfer member that is transferred to the recording medium, and a contact point where the first regulating member and the back surface of the image holding member abut on an upstream side in a circumferential direction of the image holding member, A second regulating member that regulates the transport position of the recording medium by sandwiching the recording medium therebetween, and presses the surface of the image holding body via the recording medium to bend the image holding body, It is characterized by providing.

  The transfer device according to a second aspect of the present invention is the transfer device according to the first aspect, wherein the first restricting member is a columnar rotating member that rotates following the rotation of the image holding body, and the rotating member. Is disposed on the opposite side of the second restricting member across the image carrier, the second restricting member is plate-shaped, and the tip of the second restricting member that contacts the recording medium being conveyed is When viewed from the thickness direction of the second restricting member, the center side in the width direction has an arc shape that protrudes downstream in the circumferential direction of the image carrier.

  According to a third aspect of the present invention, there is provided the transfer device according to the first aspect, wherein a support member that supports the back surface of the image carrier is provided on the opposite side of the second regulating member across the image carrier. The second restricting member is plate-shaped, and the front end of the second restricting member that contacts the recording medium to be conveyed is viewed from the thickness direction of the second restricting member. The arcuate shape is convex toward the downstream side in the circumferential direction of the body.

  An image forming apparatus according to a fourth aspect of the present invention transfers a toner image held on the surface of the endless image holding member that holds the toner image on the surface and the toner image held on the surface of the image holding member to a recording medium. And a transfer device according to any one of claims 1 to 3.

  According to the transfer device of the first aspect of the present invention, when the image carrier is not bent by the pressing force of the second regulating member that regulates the conveyance position of the recording medium by sandwiching the recording medium with the image carrier. In contrast, when the toner image formed on the image holding member is transferred to a recording medium using the discharge electrode, it is possible to suppress toner image transfer defects (white spots).

  According to the transfer device of the second aspect of the present invention, the toner is more effective than the case where the image carrier is not sandwiched between the rotating member that regulates the circulation path of the image carrier and the second regulating member. Image transfer failure can be suppressed.

  According to the transfer device of the third aspect of the present invention, the toner image transfer defect is effectively suppressed as compared with the case where the support member is not provided on the opposite side of the second regulating member across the image holding member. can do.

  According to the image forming apparatus of the fourth aspect of the present invention, compared to the case where the transfer device according to any one of the first to third aspects is not provided, an image is formed particularly on both sides of the recording medium. In this case, transfer failure of the toner image can be suppressed.

It is the side view which showed the transfer apparatus which concerns on 1st Embodiment of this invention. It is the side view which showed the transfer apparatus which concerns on 1st Embodiment of this invention. It is the side view which showed the transfer apparatus which concerns on 1st Embodiment of this invention. It is the side view which showed the transfer apparatus which concerns on 1st Embodiment of this invention. It is the perspective view which showed the transfer apparatus which concerns on 1st Embodiment of this invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention. It is the side view which showed the transfer apparatus which concerns on 2nd Embodiment of this invention. It is the side view which showed the transfer apparatus which concerns on 3rd Embodiment of this invention.

  An example of a transfer device and an image forming apparatus according to the first embodiment of the present invention will be described with reference to FIGS. In addition, arrow UP in a figure shows the perpendicular direction upper direction.

(overall structure)
As shown in FIG. 6, the image forming apparatus 10 is an image forming apparatus using an electrophotographic system, and includes therein a sheet feeding cassette 20 loaded with a sheet member P as a recording medium, and a sheet member. An image forming unit 14 that forms a toner image transferred to P, a transfer unit 22 as an example of a transfer device that transfers the toner image to the sheet member P, a fixing device 12 that fixes the toner image to the sheet member P, A sheet conveyance system including a conveyance roll 18 that conveys the sheet member P along the conveyance path 30 and a control unit 50 that controls the operation of the entire image forming apparatus 10 are provided. In the present embodiment, four paper feed cassettes 20 are provided.

  Further, an endless image carrier belt 16 as an example of an image carrier, and the image carrier belt 16 are wound around the image forming unit 14 and rotate to transmit driving force to the image carrier belt 16. There are provided a driving roll 32 and a plurality of driven rolls 34 around which the image carrier belt 16 is wound.

  Further, the driven roll 34 includes a driven roll 34A disposed below the driving roll 32 in the vertical direction, a driven roll 34B disposed side by side in the horizontal direction with respect to the driving roll 32, and a vertical direction below the driven roll 34B. And a driven roll 34C arranged side by side in the horizontal direction with respect to the driven roll 34A.

  The image carrier belt 16 is provided so as to extend in the horizontal direction while being wound around the drive roll 32 and each driven roll 34.

  Further, the image forming unit 14 includes a print engine 36 that forms a toner image on the surface of the image carrier belt 16. The print engine 36 includes yellow (Y), magenta (M), cyan (C), and black (K) toner images of respective colors that form toner images on the surface of the image carrier belt 16. 36K. The print engines 36Y, 36M, 36C, and 36K are arranged in the horizontal direction in this order along the circumferential direction of the image carrier belt 16 (direction of arrow A in the figure) so as to face the surface of the image carrier belt 16. Is arranged in.

  Further, each color print engine 36 includes a charger 37, an exposure head 38, and a developing device 39 that are sequentially arranged in the circumferential direction of the image carrier belt 16.

  More specifically, the charger 37 uniformly charges the image carrier belt 16 with a charging corotron, a charging roll, or the like. The exposure head 38 exposes the charged surface (charged surface) of the image carrier belt 16 with an LED array, an optical scanning device (Raster Optical Scanner), or the like, based on the image data on the image carrier belt 16. An electrostatic latent image is formed.

  The developing device 39 contains a one-component developer made of toner or a two-component developer made of toner and carrier. Further, the developing device 39 includes a developing roll 39A that moves the toner contained in the developer contained therein onto the electrostatic latent image on the image carrier belt 16 while rotating. That is, the electrostatic latent image on the image carrier belt 16 is developed with toner and visualized as a toner image.

  Further, the image forming unit 14 is provided with a transfer unit 22 that transfers the toner image formed on the surface of the image carrier belt 16 to the sheet member P. The transfer unit 22 is disposed downstream of the print engine 36 in the circumferential direction of the image carrier belt 16 and the surface of the image carrier belt 16 that circulates between the driving roll 32 and the driven roll 34A. A transfer corotron 42 is provided as an example of a transfer member disposed so as to face each other.

  As shown in FIG. 1, the transfer corotron 42 has a U-shaped casing 42 </ b> A with the image carrier belt 16 side opened, and is disposed inside the housing 42 </ b> A and in the width direction of the image carrier belt 16. And a discharge wire 42 </ b> B extending in the depth direction of the drawing. Then, the transfer corotron 42 gives a non-contact charge of a polarity opposite to the toner charge to the back surface of the sheet member P conveyed while being overlapped with the surface of the image carrier belt 16, thereby transferring the toner image on the image carrier belt 16. The image is transferred to the sheet member P. Details of the transfer unit 22 will be described later.

  Further, as shown in FIG. 6, the untransferred residue remaining on the image carrier belt 16 on the downstream side in the circumferential direction of the image carrier belt 16 (hereinafter simply referred to as the downstream side in the circumferential direction) with respect to the transfer unit 22. A cleaning mechanism 44 for removing toner from the image carrier belt 16 is provided.

  Further, the fixing device 12 is provided on the downstream side in the transport direction of the sheet member P with respect to the transfer unit 22 (image forming unit 14). The fixing device 12 is provided with a heat roll 46 that heats and rotates in contact with the transfer surface of the sheet member P, and a pressure roll 48 that presses the heat roll 46 while rotating the sheet member P. Yes. A fixing nip N is formed by the heat roll 46 and the pressure roll 48.

  Further, on the downstream side of the sheet conveying direction of the sheet member P with respect to the fixing device 12, the sheet member P on which the image is formed is discharged by the sheet discharge roll 24, and there is some trouble during the conveyance, which is unnecessary. A purge tray 27 from which the sheet member P is discharged is provided. In the present embodiment, two stackers 26 are provided.

  In addition, when the images are formed on the front and back of the sheet member P on the downstream side in the conveyance direction of the sheet member P with respect to the fixing device 12, the sheet member P having the toner image fixed on the surface reverses the front and back. The back surface conveyance path 28 sent in is provided. Further, a conveyance belt 29 that conveys the sheet member P unloaded from the back surface conveyance path 28 toward the conveyance path 30 is provided below the back surface conveyance path 28 in the vertical direction. In addition, the sheet member P carried out from the paper feed cassette 20 disposed below the back surface conveyance path 28 in the vertical direction is also conveyed toward the conveyance path 30 by the conveyance belt 29.

  With the above configuration, in the image forming apparatus 10, first, a toner image is formed on the image carrier belt 16 by the print engines 36 of the respective colors provided in the image forming unit 14. The sheet member P that is unloaded from the sheet feeding cassette 20 and conveyed along the conveyance path 30 by the plurality of conveyance rolls 18 and the conveyance belt 29 is conveyed to the transfer unit 22. In the transfer unit 22, the sheet member P is conveyed so as to overlap the image carrier belt 16, and the toner image on the image carrier belt 16 is transferred to the sheet member P by the transfer corotron 42.

  Specifically, as shown in FIG. 2, the transfer corotron 42 discharges toward the image carrier belt 16 whose circulation path is restricted by a backup roll 60 described later, and holds the sheet member P in the discharge region. The body belt 16 is electrostatically adsorbed. Further, the transfer corotron 42 transfers the toner image held on the image carrier belt 16 in the discharge region to the sheet member P conveyed while being overlapped on the surface of the image carrier belt 16.

  Then, as shown in FIG. 6, the sheet member P to which the toner image has been transferred is pressurized and heated by the fixing device 12 on the downstream side in the transport direction of the transfer unit 22, and the toner image is fixed to the sheet member P. Further, the sheet member P on which the toner image is fixed is discharged to the stacker 26 by the transport roll 18 and the discharge roll 24.

  Further, when images are formed on both the front and back sides of the sheet member P, the sheet member P with the toner image fixed on the front surface is reversed by switching the conveyance path on the downstream side in the conveyance direction of the fixing device 12. Is transported to the rear surface transport path 28. Then, the sheet member P whose front and back sides are reversed is transported to the transfer unit 22 by the transport belt 29, and the toner image is again transferred from the image carrier belt 16 to the back surface. Then, the sheet member P passes through the fixing device 12, the toner image is fixed on the back surface of the sheet member P, and the sheet member P is discharged to the stacker 26 by the discharge roller 24.

(Main part configuration)
Next, the transfer unit 22 and the like will be described.

  As shown in FIG. 2, the sheet member P fed from the conveyance roll 18 </ b> A overlaps the image carrier belt 16 between the conveyance roll 18 </ b> A that feeds the sheet member P into the transfer unit 22 and the transfer unit 22. A guide member 54 for guiding is provided.

  Further, the transfer unit 22 provided between the drive roll 32 and the driven roll 34A includes the transfer corotron 42 described above, a backup roll 60 as an example of a first regulating member that supports the back surface of the image carrier belt 16, and A transfer blade 64 is provided as an example of a second regulating member that regulates the conveying position of the sheet member P by sandwiching the sheet member P with the image carrier belt 16.

  Specifically, the backup roll 60 formed in a columnar shape is disposed between the drive roll 32 and the driven roll 34 </ b> A and is driven with respect to the image carrier belt 16 that circulates against the back surface of the image carrier belt 16. It is designed to rotate.

  Further, on the downstream side in the circumferential direction with respect to the backup roll 60, similarly to the backup roll 60, a backup roll 62 that is driven to rotate against the back surface of the image carrier belt 16 is provided. The rotation path of the image carrier belt 16 that circulates when the backup roll 62 and the backup roll 60 come into contact with the back surface of the image carrier belt 16 is regulated.

  The mounting position of the transfer corotron 42 is determined so that the discharge area of the image carrier belt 16 by the transfer corotron 42 is downstream in the circumferential direction with respect to the contact C between the backup roll 60 and the image carrier belt 16. Yes.

  Further, a sheet member between the image carrier belt 16 on the upstream side in the circumferential direction of the image carrier belt 16 with respect to the contact C (hereinafter simply referred to as the upstream side in the circumferential direction) and the image carrier belt 16 on the upstream side in the circumferential direction with respect to the contact C The transfer blade 64 described above sandwiching P is provided.

  Specifically, as shown in FIGS. 1 and 3, the transfer blade 64 has a plate shape formed of a resin material, and is supported rotatably around a rotation shaft 66 extending in the width direction of the image carrier belt 16. ing. Then, the transfer blade 64 presses the surface of the image carrier belt 16 via the sheet member P (solid line shown in FIGS. 1 and 3), and a retreat position that retreats away from the image carrier belt 16. (A two-dot chain line shown in FIGS. 1 and 3). Specifically, the backup roll 60 supports the pressing force by the transfer blade 64 at the pressing position.

  The rotating shaft 66 is connected to a stepping motor 68 (hereinafter simply referred to as a motor 68) that transmits a rotational driving force to the rotating shaft 66. Further, a control unit 70 is provided for controlling the rotation angle of the motor 68 to move the transfer blade 64 between the pressing position and the retracted position.

  Further, as shown in FIG. 5, the tip of the transfer blade 64 that contacts the sheet member P has an arc shape in which the central side in the width direction is convex toward the downstream side in the circumferential direction when viewed from the thickness direction of the transfer blade 64. Has been.

(Function)
Next, the operation of the transfer unit 22 will be described.

  As shown in FIG. 2, when the sheet member P is not conveyed to the transfer unit 22, the control unit 70 controls the rotation angle of the motor 68 so that the transfer blade 64 is disposed at the retracted position. .

  With the transfer blade 64 disposed at the retracted position, the sheet member P conveyed by the conveyance roll 18A is guided by the guide member 54 so as to overlap the circulating image carrier belt 16, and conveyed toward the transfer unit 22. Is done.

  Further, as shown in FIGS. 1 and 3, the control unit 70 controls the rotation angle of the motor 68 so that the front end of the conveyed sheet member P is sandwiched between the backup roll 60 and the transfer blade 64. The transfer blade 64 is moved from the retracted position to the pressing position.

  Specifically, the control unit 70 considers the detection signal of a detection member (not shown) that detects the leading end of the conveyed sheet member P and the time elapsed since the detection signal was received, and the motor 68. , The transfer blade 64 is moved from the retracted position to the pressed position.

  When the transfer blade 64 moves to the pressing position, the transfer blade 64 presses the surface of the image carrier belt 16 via the sheet member P, and the image carrier belt 16 is bent and a part of the image carrier belt 16 is moved. Winds around the surface of the backup roll 60. When the image carrier belt 16 is pressed and bent by the transfer blade 64, the conveyance path of the conveyed sheet member P becomes curved in a side view, and the conveyance direction of the sheet member P is changed (in FIG. 3, the arrow D). Direction to arrow E direction).

  Further, as shown in FIG. 5, the tip of the transfer blade 64 formed of a resin material presses the image carrier belt 16 while being bent downstream in the circumferential direction.

  As shown in FIG. 4, when the trailing end of the conveyed sheet member P attempts to pass through the leading end of the transfer blade 64, the control unit 70 controls the rotation angle of the motor 68 to transfer the transfer blade 64. Is moved from the pressed position to the retracted position.

  As described above, when the image carrier belt 16 is pressed and bent by the transfer blade 64, the conveyance path of the conveyed sheet member P becomes curved in a side view and the conveyance direction is changed (in FIG. 3, an arrow). D direction can be changed to arrow E direction). For this reason, the force which tries to extend to the sheet member P in the width direction acts, and the wrinkle which arose in the sheet member P extends.

  Further, since wrinkles generated in the sheet member P extend, transfer defects (white spots) are suppressed when the toner image is transferred to the sheet member P.

  In particular, in the case of double-sided printing in which images are formed on the front and back surfaces of the sheet member P, wrinkles may occur in the sheet member P on which images are formed on the surface of the sheet member P. However, since the wrinkles are extended as described above, the transfer failure is similarly suppressed when the toner image is transferred to the back surface of the sheet member P.

  In addition, since the tip of the transfer blade 64 has an arc shape, the pressing force with which the transfer blade 64 presses the sheet member P on the center side in the width direction of the conveyed sheet member P is the width of the sheet member P. It becomes larger than the pressing force on the outside in the direction. Accordingly, the sheet member P is pulled outward in the width direction, and the wrinkles generated in the sheet member P are extended.

  Next, an example of a transfer device and an image forming apparatus according to the second embodiment of the present invention will be described with reference to FIG. In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 7, unlike the first embodiment, in the second embodiment, the image carrier belt 16 is not sandwiched between the backup roll 60 and the transfer blade 64, and the image carrier belt 16. A support member 80 that supports the back surface of the image carrier belt 16 is provided on the opposite side of the transfer blade 64 with respect to the transfer blade 64.

  That is, when the image carrier belt 16 is sandwiched between the support member 80 and the transfer blade 64, the circulation path of the image carrier belt 16 is restricted. Thereby, the conveyance path | route of the sheet | seat member P is regulated.

  Next, an example of a transfer device and an image forming apparatus according to the third embodiment of the present invention will be described with reference to FIG. In addition, about the same member as 2nd Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 8, unlike the second embodiment, in the third embodiment, a support member that supports the back surface of the image carrier belt 16 is not provided. The tip of the transfer blade 82 is not arcuate, and the end edge of the tip of the transfer blade 82 is a straight line extending in the width direction.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above-described embodiment, as the image carrier belt, a so-called photosensitive belt in which a toner image is directly formed on the belt has been described as an example. However, the configuration of the present invention is used for a so-called transfer belt to which a toner image is transferred. Also good.

  In the above-described embodiment, the backup roll 60 that is rotatably supported is described in order to regulate the circulation path of the image carrier belt 16, but the image carrier is not limited to the backup roll. For example, a non-rotating plate-like member may be applied to the back surface of the image carrier belt as long as it is a member that regulates the belt circulation path. In this case, the plate-like member is preferably a member that supports the image carrier belt in an arc shape.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 16 Image carrier belt (an example of an image carrier)
22 Transfer section (an example of a transfer device)
42 Transfer corotron (an example of a transfer member)
60 backup roll (example of first regulating member and rotating member)
64 Transfer blade (example of second regulating member)
80 Support member 82 Transfer blade (an example of a second regulating member)

Claims (4)

A first restricting member for restricting a circulation path of the image holding body that hits the back surface of the endless image holding body that rotates while holding the toner image on the surface;
A sheet-like shape that discharges toward the image carrier whose circulation path is regulated by the first regulating member, and that conveys the toner image held on the image carrier in a discharge region while overlapping the surface of the image carrier. A transfer member to be transferred to the recording medium,
With respect to the contact point where the first regulating member and the back surface of the image holding member hit each other, the recording medium is provided between the image holding member and the upstream side in the circumferential direction of the image holding member. A second regulating member that regulates the transport position of the recording medium and that deflects the image holding body by pressing the surface of the image holding body through the recording medium;
A transfer apparatus comprising: The first restricting member is a columnar rotating member that rotates following the rotation of the image holding member, and the rotating member is disposed on the opposite side of the second restricting member across the image holding member. And
The second restricting member is plate-shaped, and the front end of the second restricting member that contacts the recording medium to be conveyed is viewed from the thickness direction of the second restricting member, and the center side in the width direction is the image holding member. The transfer device according to claim 1, wherein the transfer device has an arc shape that protrudes downstream in the circumferential direction. On the opposite side of the second regulating member across the image carrier, a support member that supports the back surface of the image carrier is provided,
The second restricting member is plate-shaped, and the front end of the second restricting member that contacts the recording medium to be conveyed is viewed from the thickness direction of the second restricting member, and the center side in the width direction is the image holding member. The transfer device according to claim 1, wherein the transfer device has an arc shape that protrudes downstream in the circumferential direction. An endless image carrier that holds and revolves the toner image on the surface;
The transfer device according to any one of claims 1 to 3, wherein the toner image held on the surface of the image carrier is transferred to a recording medium.
An image forming apparatus comprising:

Images