JP2006030714A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry a sheet to a next stage without disturbing a toner image on a transferred surface of the sheet and to prevent a transfer means corresponding to a non-transferred surface of the sheet from deviating from a transfer position to damage the transfer means or dirtying this surface of the sheet. <P>SOLUTION: This image forming apparatus capable of mode switching for forming a toner image on one surface or both surfaces of a sheet 10 is provided with toner image carriers (21 and 31) disposed in proper positions on both surface sides of the carried sheet to carry toner images and transfer means (29 and 70) for transferring toner images on the toner image carriers (21 and 31) to the sheet 10, and transfer means (29 and 70) are provided with contact/separation means (80 and 90) by which they are released from transfer positions of the sheet 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention has a mode switching in which the sheet is conveyed in one direction and the toner image is selectively transferred to both sides or one side of the sheet. When the toner image is transferred only to one side of the sheet, The present invention relates to an image forming apparatus that can transfer the toner image transferred to the surface to the next step without being disturbed.

  Patent Document 1 discloses a configuration for transferring toner onto both surfaces of a sheet. In this configuration, as disclosed in [0041] and [FIG. 7], the first printing station 4 combining the printing unit and the intermediate transfer belt 36 and the first printing station 4 are symmetrical. And a second printing station 41 having a configuration. The first printing station 4 and the second printing station (back surface printing station) 41 are arranged in parallel in line symmetry.

  In such a configuration, the recording sheet 3 is vertically conveyed between the printing station 4 and the back surface printing station 41, and a full color image 244 formed on the intermediate transfer belt 36 by the retransfer unit 38 at the upper part of the printing station 4. Is transferred to one surface (front surface) of the recording paper 3.

Next, the recording paper 3 is changed in the conveying direction by the folding roll 34, and the second full-color image 245 formed on the second intermediate transfer belt 361 is recorded by the second retransfer means 381 at the upper part of the back surface printing station 41. It is transferred to the other side (back side) of the paper 3.
JP 2002-268320 A

  Under this configuration, nothing is disclosed about transferring a full-color image to only one side of the recording paper 3. Further, as shown in FIG. 7, since the recording paper 3 is transported in one direction, the recording paper 3 is always brought into contact with the intermediate transfer belts 36 and 361, and in this state, the intermediate transfer belt 36, 361 must be rotated.

  For this reason, for example, when only the surface of the recording paper 3 is transferred, the conveyance of the recording paper 3 is always in a state where the back surface of the recording paper 3 rubs the intermediate transfer belt 361. There is a problem of scratching. In addition, there is a problem that the full-color image transferred to the front surface of the recording paper 3 is disturbed, and dirt on the intermediate transfer belt 361 moves to the back surface of the recording paper 3.

  In order to solve the above problem, according to the present invention, in the image forming apparatus capable of mode switching so as to form a toner image on one side of the sheet or both sides of the sheet, both sides of the conveyed sheet are provided. A toner image carrier that is disposed at an appropriate position on the side and carries a toner image, and first and second transfer means that transfer the toner image on the toner image carrier to a sheet, and at least one of the transfer means And a contact / separation means for releasing the sheet from the transfer position of the sheet.

  According to a second aspect of the present invention, the transfer means includes guide means that acts so that the sheet comes into contact with the toner carrying member, and the guide means is a transfer means for the other surface in a mode in which a toner image is formed only on one surface of the sheet. Is formed so as to be separated from the corresponding toner image carrier.

  According to a first aspect of the present invention, in an image forming apparatus capable of mode switching so as to form a toner image on one side of the sheet or both sides of the sheet, the toner image is carried at an appropriate position on both sides of the conveyed sheet. A toner image carrier and first and second transfer means for transferring the toner image on the toner image carrier to the sheet; and a contact / separation means for releasing at least one of the transfer means from the sheet transfer position. By providing, the sheet can be transported to the next process without disturbing the toner image on the surface of the transferred sheet. Further, it is possible to prevent the transfer means corresponding to the surface of the sheet on which the transfer is not performed from being detached from the transfer position, and scratching the transfer means or soiling the surface of the sheet.

  According to a second aspect of the present invention, the transfer unit includes a guide unit that acts to bring the sheet into contact with the toner carrying member, and the guide unit includes a transfer unit for the other side in a mode in which a toner image is formed only on one side of the sheet. In addition to the effect of the first aspect, the transfer efficiency can be increased by forming the toner image carrier so as to be separated from the corresponding toner image carrier.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional configuration diagram of a main part of an image forming apparatus of the present invention. As shown in FIG. 1, a color image is transferred to the front and back surfaces of a continuous web 10 such as continuous paper in the order of front and back, and then these unfixed color images are fixed together in front and back.

  The image forming means for forming a color image is roughly divided into a first image forming means 20 for forming a color image on the surface (lower surface in the drawing) of the continuous web 10 (hereinafter simply referred to as a sheet), and It comprises second image forming means 30 for forming a color image on the back surface (upper surface in the figure) of the sheet 10. As shown in the figure, the first image forming unit 20 and the second image forming unit 30 have a substantially bilateral configuration, and the first image forming unit 20 is in order from the bottom with respect to the transfer belt 21. , Yellow (Y), magenta (M), cyan (C), and black (BK) images are formed, and the color image formed on the top of the transfer belt 21 is transferred to the surface of the sheet.

  In contrast, the second image forming unit 30 forms yellow (Y), magenta (M), cyan (C), and black (BK) images on the transfer belt 31 in order from the top. The image is transferred to the back surface of the sheet at the lower end of 31.

  For this reason, in the following, the formation of a black image on the black toner photoconductor BK1 of the first image forming unit will be described with respect to the image forming apparatus disposed around the black image forming unit, but the other photosensitive drums Y1, M1, and C1 are described. Similar image forming devices are also arranged around BK1, Y2, M2, C2, and BK2.

  The photosensitive drum BK1 has a structure in which a well-known photosensitive member such as an OPC photosensitive member or an amorphous silicon photosensitive member is provided on the surface of a cylindrical substrate such as aluminum. As shown in FIG. 1, the photosensitive drum BK1 rotates clockwise at a predetermined speed when operated. . Around the photosensitive drum BK1, in order of operation, an eraser lamp 22 for removing residual charges on the photosensitive drum BK1, a corona charger 23 for uniformly charging the surface of the photosensitive drum BK1 to a specific polarity, and the surface of the charged photosensitive drum BK1 The LED exposure device 24 for forming an electrostatic latent image based on desired information by projecting a digital optical signal corresponding to the black signal onto the surface, and the electrostatic latent image formed on the surface of the photosensitive drum BK1 as black toner The developing device 25 that develops the toner and the transfer roller (or the transfer corona release) that transfers the toner image formed on the photosensitive drum BK1 to the surface of the transfer belt 21 by charging from the back side of the transfer belt 21 with the opposite polarity to the toner. Electric device) 26, and a cleaner 27 for removing toner powder remaining on the surface of the photosensitive drum BK1 after transfer.

  Similarly to the photosensitive drum BK1, the photosensitive drums Y1, M1, and C1 are provided with the eraser lamp, the corona charger, the LED exposure device, the developing device, the transfer roller, and the cleaner, respectively. The photosensitive drum Y1 uses yellow, M1 uses magenta, and C1 uses cyan based on the color image signal corresponding to each color, and the corresponding color toner is used.

  In order to temporarily support the toner images of the respective colors formed by the photosensitive drums (BK1, Y1, M1, C1), toner image carriers (21, 31) called so-called intermediate transfer members are provided. The toner image carrier may be in the form of a drum (intermediate transfer drum), and will be described as a belt in the illustrated example. The transfer belt 21 which is a toner image carrier is composed of a wide film-like endless belt having a dielectric surface (toner image carrier surface), and in the illustrated example, two support rollers 28a and 28b provided at intervals in the vertical direction. When the image is formed, the photosensitive drums Y1, M1, C1, and BK1 move in the counterclockwise direction at the same speed as the peripheral speed. In this embodiment, the toner image carrier will be described with reference to the transfer belt 21. Along with this movement, a yellow toner image formed on the photosensitive drum Y1 on the surface of the transfer belt 21, and then a magenta toner image and a cyan toner formed on each of the photosensitive drums M1, C1, and BK1. The image and the black toner image are sequentially transferred and laminated to form a full-color toner image or a multi-color toner image.

  Of the two support rollers 28a, 28b that support the transfer belt 21, at least the upper support roller 28b is in contact with the back surface of the transfer belt 21 over the entire width in the axial direction so as to face the support roller 28a. The transfer means 29 is disposed in pressure contact with the surface of the transfer belt 21. The surfaces of the support rollers 28a and 28b are subjected to blast mesh processing so that slippage does not occur at the contact portion of the transfer belt 21.

  The transfer means 29 on the first image forming means 20 side is connected to a bias power source (not shown), and a transfer device 61 (transfer charger) to which a predetermined transfer bias is applied during image formation and a peeling device 62 (static charge). Instrument) 60. On both sides of the transfer means 29, rollers (63, 63) serving as guide means for the sheet 10 are provided. In the following description, the guide means will be described as rollers (63, 63) and a guide roller 73 described later. These rollers (63, 63) are located on the inner side of the position of the sheet 10 where the first and second transfer means (29, 27) are released from the transfer position (tangent line between the feed roller 3 and the roller 73, two-dot chain line). It is arranged to be located in. With this arrangement, the rollers (63, 63) act so that the surface of the moving sheet 10 comes into contact with the transfer belt 21 side, so that the full-color toner image or multi-color toner image formed on the transfer belt 21 is on the sheet. In order to transfer efficiently even in a state where the transfer position is inclined on the surface, the transfer roller 3 and the transfer means 29 are cooperated with the feed roller 3 to widen the width of the transfer portion and the apparatus is in operation. In addition, it is possible to eliminate the sagging of the sheet 10 by applying tension to the sheet 10.

  Further, the transfer means 70 on the second image forming means 30 side includes a transfer device (transfer charger) 71 and a peeling device (static charger) 72. The transfer device (transfer charger) 71 and the peeling device (charge eliminating charger) 72 are composed of a corona wire and a corona house covering the corona wire.

  An appropriate number of corona wires are stretched inside the corona house, one in the illustrated example, and the corona wires and the corona house extend in the width direction of the transfer belt 31. The corona house is grounded and is disposed to face the transfer belt. Further, a guide roller 73 is provided on the upstream side of the transfer device (transfer charger) 71. The guide roller 73 conveys the sheet 10 to the second image forming means 30 side and cooperates with the rollers (63, 63) of the transfer means 29 on the first image forming means 20 side to A predetermined tension is applied. In this embodiment, the transfer means (29, 70) are a transfer device (transfer charger) (61, 71) and a peeling device (static charger) (62, 72), but are not limited thereto. It may be a transfer law.

  Thus, the sheet 10 made of continuous paper is fed between the transfer means 29 and the transfer belt 10 by the feed roller 3, and after the full-color toner image or multi-color toner image is transferred from the transfer belt 21 to the surface thereof, Guided downward with a certain inclination, sent to the transfer means 70 of the second image forming means 30 by the guide roller 73, and the color toner image is transferred to the back surface. The sheets 10 carrying the unfixed color toner images on the front and back surfaces are conveyed to a fixing device (not shown) for both-side batch fixing.

  The transfer means on the first image forming means 20 side and the transfer means 70 on the second image forming means 30 side respectively transfer the full color toner image or the multicolor toner image from the transfer position onto the front and back surfaces of the sheet 10. (29, 70) are provided independently or in conjunction with each other or are released from synchronization, that is, contact / separation means 80 for retracting these transfer means (29, 70) away from the toner image carrier (21, 31) is provided. It has been.

  The contact / separation means 80 of the transfer means 29 on the first image forming means 20 side attaches the transfer means 29 and each roller 63 to the frame body 81 so that it swings within a predetermined range (arrow direction A). The frame is pivotally supported by a frame of a device (not shown). When the toner image is transferred only to the other surface, the urging means 83 causes the frame to act and pivot about the support shaft 82 in the direction of the two-dot chain line.

  Further, the contact / separation means 90 of the transfer means 70 on the second image forming means 30 side is configured to attach the transfer means 70 and the guide roller 73 to the frame body 91 and shift to a predetermined range in the arrow direction B. Yes. When the toner image is transferred only to the other surface, the urging means 91 causes the frame body 91 to act and shift in the direction of the two-dot chain line.

As shown in FIG. 2, the contact / separation means 80 of the transfer means 29 on the first image forming means 20 side and the contact / separation means 90 of the transfer means 70 on the second image forming means 30 side are respectively drive means ( 84, 92) to the control means 1. Each driving means (84, 92) operates each contacting / separating means (80, 90). Further, the control means 1 is connected to the input means 2, and based on the user input or information from the apparatus, the drive means (84, 93) release and return the respective transfer means (29, 70) from the transfer position. ).

  In such a configuration, when the user wants to output a full-color toner image or a multi-color toner image (hereinafter referred to as a toner image) only on one surface (front surface) of the sheet 10 (single-sided output mode), The surface on which the toner image is to be output is input to the input means. At this time, each transfer means (29, 70) is arranged so that the front and back surfaces of the sheet 10 do not come into contact with the transfer belt (21, 31) and the surface of the transfer belt is not damaged. , 31) is released from the transfer position. Even when the toner image cannot be transferred to the sheet 10 due to a jam or the like, the transfer means (29, 70) are released from the transfer position. In this state, the sheet 10 is given a predetermined tension by the feed roller 3 and the roller 73 to prevent the sheet from sagging, and the sheet 10 can be conveyed stably.

  Based on information from the input means 2, the control means 1 activates the urging means 83 via the drive means 84 in the case of information for outputting this toner image on the front side. At this time, the roller 73 of the transfer device 70 on the second image forming unit 30 side released from the transfer position applies a predetermined tension to the sheet 10 to prevent the sheet 10 from sagging. Thereby, it is possible to prevent the slack portion of the sheet 10 from coming into contact with the fixing device in the next process.

  Further, as another correspondence of the single-sided output mode, when the user wants to output a toner image only on the other side (back side) of the sheet 10, the operation is performed as described above. At this time, the transfer device 29 on the first image forming means 20 side is released (separated) from the transfer position around the support shaft 82. At this time, the sheet passing through the first image forming means 20 is prevented from sagging of the sheet 10 to which a predetermined tension is applied by the feed roller 3 and the roller 73 of the transfer device 70.

  Further, when outputting a toner image on both sides of the sheet 10 and in the double-sided output mode, the information is input from the input means 2, and the control means 1 is based on the information, and the driving means (84, 93). ), The respective biasing means (83, 91) are operated to return the transfer means (29, 70) to the transfer position.

  As described above, the transfer sheet (29, 70) is provided with the contact / separation means (80, 90) for returning and releasing the transfer means (29, 70) at the transfer position of the sheet, whereby the transferred sheet 10 is transferred. The sheet 10 can be conveyed to the next process without disturbing the toner image on the surface. Further, it is possible to prevent the transfer means corresponding to the surface of the sheet 10 on which the transfer is not performed from leaving the transfer position and scratching the transfer means or soiling the surface of the sheet.

1 is a cross-sectional configuration diagram of a main part of an image forming apparatus of the present invention. The block diagram which operates the contact / separation means.

Explanation of symbols

10 Sheets 21, 31 Toner image carrier 29, 70 Transfer means 63, 67 Guide means 80, 90 Contact / separation means

Claims (2)

In an image forming apparatus capable of mode switching so as to form a toner image on one side or both sides of a sheet,
A toner image carrier that is disposed at appropriate positions on both sides of the conveyed sheet and carries a toner image; and first and second transfer units that transfer the toner image on the toner image carrier to the sheet. ,
An image forming apparatus comprising: a contacting / separating unit that releases at least one of the transfer units from the transfer position of the sheet. The transfer means includes a guide means that acts to bring a sheet into contact with the toner carrier,
The mode of forming the toner image only on one surface of the sheet, the guide means is formed so that the transfer means for the other surface is separated from the corresponding toner image carrier. The image forming apparatus according to 1.

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