JP2011020801A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of further effectively and uniformly adjusting a curl quantity of paper by using the heat of a fixing unit. <P>SOLUTION: The image forming device has the fixing unit 7 for fixing a toner after being transferred to the paper, a carrier roller 12b for carrying the paper ejected from the fixing unit 7, a carrier roller for ejecting the paper ejected from the carrier roller 12b, and a moving mechanism control part for controlling so as to move the carrier roller 12b according to the curl direction of the paper. A carrying guide is also arranged between the carrier roller 12b and the fixing unit 7, and the carrying guide is also moved simultaneously when moving the carrier roller 12b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  An image forming apparatus employing an electrophotographic system forms an electrostatic latent image on a peripheral surface of a photosensitive drum by light irradiation from an exposure device based on predetermined image information, and a toner from a developing device is formed on the electrostatic latent image. To form a toner image, and the toner image is transferred to a sheet. The sheet on which the toner image has been transferred is subjected to a fixing process of the toner image by a fixing device (fixing unit), and is then discharged to a discharge tray.

  The fixing unit includes a heat roller provided with a heater for heating inside, and a pressure roller disposed so as to face the peripheral surface of the heat roller so as to contact the peripheral surface of the heat roller. Then, the sheet after the transfer process passes through the nip portion between the heat roller that is driven and rotated and the pressure roller to obtain heat from the heat roller and is subjected to the fixing process.

  By the way, when the sheet passes through the nip portion, the front side (the side where the toner image is transferred) of the sheet is heated by the heat roller, while the back side is in contact with the pressure roller having a low temperature. For this reason, the front side of the sheet is thermally expanded, and thus, the sheet discharged from the fixing device is formed with a so-called curl in which both sides in the width direction are warped toward the pressure roller. When such a curl is formed, the sheet becomes bulky in the vertical direction, which causes a disadvantage that the discharge tray cannot secure a preset discharge amount.

  Therefore, a technique for making the curl amount uniform by removing the curl of the paper has been conventionally known (see, for example, Patent Document 1 and Patent Document 2).

JP 2008-81268 A JP 2002-193525 A

  However, the curl removal apparatus described in Patent Document 1 has a problem that curl in both directions cannot be removed only by removing curl in one direction.

  In addition, as described in Patent Document 2, when the curl amount is adjusted immediately before paper discharge, the temperature of the paper decreases while moving on the conveyance path, and the paper cannot be deformed so much. . Therefore, there is a problem that the effect is weak even when curl adjustment is performed.

  In particular, Patent Document 2 is applied to a color thermal printer. In recent years, an image forming apparatus represented by a digital multi-function peripheral has a high image forming speed (paper conveyance speed). In the case of such an apparatus, it is remarkable that even if an attempt is made to suppress the curl amount, the state cannot be suppressed as much as desired immediately before paper discharge.

  In view of the above-described problems, an object of the present invention is to provide an image forming apparatus capable of more effectively adjusting the curl amount of a sheet more effectively by using heat of a fixing unit. .

  In view of the above-described problems, the image forming apparatus of the present invention includes a fixing unit that fixes the toner after transfer onto a sheet, a first conveyance roller that conveys the sheet discharged from the fixing unit, and the first conveyance. A second transport roller that discharges the paper discharged from the roller; and a movement mechanism control unit that performs control to move the first transport roller according to a curl direction of the paper. To do.

  The image forming apparatus of the present invention further includes a conveyance guide between the fixing unit and the first conveyance roller, and the moving mechanism control unit moves the first conveyance roller. The conveyance guide is also moved together.

  In addition, the image forming apparatus of the present invention further includes an operation unit for instructing and operating the movement amount of the first conveying roller, and the moving mechanism control unit is based on the movement amount instructed by the operation unit. The first conveying roller is controlled to move.

  The image forming apparatus of the present invention includes a fixing unit that fixes the toner after transfer onto a sheet, and a conveyance roller that conveys the sheet discharged from the fixing unit, and the image forming apparatus is provided between the fixing unit and the conveyance roller. And a movable guide for suppressing curling of the paper and a moving mechanism control unit for controlling the movable guide according to the curling direction of the paper.

  In addition, the image forming apparatus of the present invention further includes an operation unit for instructing and operating the position of the movable guide, and the moving mechanism control unit is based on the position instructed and operated by the operation unit. Control for adjusting the guide is performed.

  According to the present invention, the fixing unit that fixes the toner after transfer onto the paper, the first transport roller that transports the paper discharged from the fixing unit, and the paper discharged from the first transport roller are discharged. A second conveyance roller and a movement mechanism control unit that performs control to move the first conveyance roller in accordance with the curl direction of the sheet are provided. Thus, by moving the first transport roller that transports the paper discharged from the fixing unit, the paper is heated immediately after passing through the fixing unit, and the curl is adjusted in a state where the paper is more easily deformed. be able to.

1 is a cross-sectional view of an image forming apparatus in the present embodiment. FIG. 2 is a diagram for describing a functional configuration of an image forming apparatus in the present embodiment. It is a figure for demonstrating the movement mechanism control in this embodiment. It is a figure for demonstrating the movement mechanism control in this embodiment.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus 100 in which an optical scanning device to which the present invention is applied is used.

  The image forming apparatus 100 forms multicolor and single color images on a predetermined sheet (recording sheet) in accordance with image data transmitted from the outside. The image forming apparatus 100 includes an apparatus main body 110, an automatic document processing apparatus 120, and the like. It is comprised by. The apparatus main body 110 includes an exposure unit 1, a developing device 2, a photosensitive drum 3, a cleaner unit 4, a charger 5, an intermediate transfer belt unit 6, a fixing unit 7, a paper feed cassette 81, a paper discharge tray 91, and the like. It is configured.

  A document placing table 92 made of transparent glass on which a document is placed is provided on the upper portion of the apparatus main body 110, and an automatic document processing device 120 is attached to the upper side of the document placing table 92. The automatic document processing device 120 automatically conveys the document on the document placing table 92. The document processing device 120 is configured to be rotatable in the direction of arrow M, and the document can be placed manually by opening the document table 92.

  The image data handled in this image forming apparatus corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Accordingly, four developing devices 2, photosensitive drums 3, charging devices 5, and cleaner units 4 are provided to form four types of latent images corresponding to the respective colors, and are respectively provided in black, cyan, magenta, and yellow. These are set to form four image stations.

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In addition to the charger type as shown in FIG. 1, a contact type roller type or brush type charger is used. Sometimes used. The exposure unit 1 corresponds to an image writing apparatus according to the present invention, and is configured as a laser scanning unit (LSU) including a laser emitting unit, a reflection mirror, and the like. The exposure unit 1 includes a polygon mirror that scans a laser beam and optical elements such as a lens and a mirror for guiding the laser beam reflected by the polygon mirror to the photosensitive drum 3. The configuration of the optical scanning device constituting the exposure unit 1 will be specifically described later. As the exposure unit 1, for example, a technique using an EL or LED writing head in which other light emitting elements are arranged in an array can be employed. The exposure unit 1 has a function of forming an electrostatic latent image corresponding to the image data on the surface thereof by exposing the charged photosensitive drum 3 according to the input image data. The developing unit 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toner of four colors (YMCK). The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The intermediate transfer belt unit 6 disposed above the photosensitive drum 3 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller 62, an intermediate transfer belt driven roller 63, an intermediate transfer roller 64, and an intermediate transfer belt cleaning unit 65. I have. Four intermediate transfer rollers 64 are provided corresponding to each color for YMCK.

  The intermediate transfer belt driving roller 62, the intermediate transfer belt driven roller 63, and the intermediate transfer roller 64 are driven to rotate while the intermediate transfer belt 61 is stretched. Each intermediate transfer roller 64 provides a transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 61.

  The intermediate transfer belt 61 is provided so as to be in contact with each photoconductor drum 3, and the toner images of the respective colors formed on the photoconductor drum 3 are sequentially transferred to the intermediate transfer belt 61 and transferred. Further, it has a function of forming a color toner image (multicolor toner image) on the intermediate transfer belt 61. The intermediate transfer belt 61 is formed in an endless shape using, for example, a film having a thickness of about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 61 is performed by an intermediate transfer roller 64 that is in contact with the back side of the intermediate transfer belt 61. A high-voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 64 in order to transfer the toner image. The intermediate transfer roller 64 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 61. In this embodiment, a roller shape is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the electrostatic images visualized on the respective photosensitive drums 3 according to the respective hues are stacked on the intermediate transfer belt 61. As described above, the laminated image information is transferred onto the sheet by the transfer roller 10 disposed at a contact position between the sheet and the intermediate transfer belt 61 described later by the rotation of the intermediate transfer belt 61.

  At this time, the intermediate transfer belt 61 and the transfer roller 10 are pressed against each other at a predetermined nip, and a voltage for transferring the toner onto the sheet is applied to the transfer roller 10 (the polarity opposite to the toner charging polarity (−)). (+) High voltage). Further, in order to obtain the nip constantly, the transfer roller 10 uses either the transfer roller 10 or the intermediate transfer belt drive roller 62 as a hard material (metal or the like), and the other as a soft material (elasticity such as an elastic roller). A rubber roller, a foaming resin roller, or the like) is used.

  Further, as described above, the toner attached to the intermediate transfer belt 61 by contacting the photosensitive drum 3 or the toner remaining on the intermediate transfer belt 61 without being transferred onto the sheet by the transfer roller 10 is used in the next step. Therefore, the intermediate transfer belt cleaning unit 65 is configured to remove and collect the toner. The intermediate transfer belt cleaning unit 65 includes a cleaning blade as a cleaning member that comes into contact with the intermediate transfer belt 61. The intermediate transfer belt 61 that comes into contact with the cleaning blade is supported by an intermediate transfer belt driven roller 63 from the back side. ing.

  The paper feed cassette 81 is a tray for storing paper (recording paper) used for image formation, and is provided below the exposure unit 1 of the apparatus main body 110. In addition, paper used for image formation can be placed in the manual paper feed cassette 82. A paper discharge tray 91 provided above the apparatus main body 110 is a tray for collecting printed sheets face down.

  In addition, the apparatus main body 110 is provided with a substantially vertical sheet conveyance path S for sending the sheets of the sheet feeding cassette 81 and the manual sheet feeding cassette 82 to the sheet discharge tray 91 via the transfer roller 10 and the fixing unit 7. It has been. In the vicinity of the paper transport path S from the paper feed cassette 81 or the manual paper feed cassette 82 to the paper discharge tray 91, pickup rollers 11a and 11b, a plurality of transport rollers 12a to 12d, a registration roller 13, a transfer roller 10, and a fixing unit. 7 etc. are arranged.

  The transport rollers 12 a to 12 d are small rollers for promoting and assisting the transport of paper, and a plurality of transport rollers 12 a to 12 d are provided along the paper transport path S. The pickup roller 11 a is provided near the end of the paper feed cassette 81, picks up paper one by one from the paper feed cassette 81, and supplies it to the paper transport path S. Similarly, the pickup roller 11 b is provided near the end of the manual paper feed cassette 82, picks up paper one by one from the manual paper feed cassette 82, and supplies it to the paper transport path S.

  Further, the registration roller 13 temporarily holds the paper being conveyed through the paper conveyance path S. The sheet has a function of conveying the sheet to the transfer roller 10 at the timing when the leading edge of the toner image on the photosensitive drum 3 is aligned with the leading edge of the sheet.

  The fixing unit 7 constitutes a fixing unit and includes a heat roller 71 and a pressure roller 72. Here, the heat roller 71 and the pressure roller 72 are configured to rotate with a sheet interposed therebetween. The heat roller 71 is set by the control unit so as to reach a predetermined fixing temperature based on a signal from a temperature detector (not shown). It has the function of fusing, mixing, and pressing the transferred multicolor toner image and thermally fixing it to the paper. An external fixing belt 73 for fixing the heat roller 71 from the outside is provided.

  Next, the paper conveyance path will be described in detail. As described above, the image forming apparatus 100 is provided with the paper feed cassette 81 for storing paper and the manual paper feed cassette 82 in advance. In order to feed paper from these paper feed cassettes 81 and 82, pick-up rollers 11a and 11b are respectively arranged to guide the paper one by one to the transport path S.

  The paper conveyed from each of the paper feed cassettes 81 and 82 is conveyed to the registration roller 13 by the conveyance roller 12a in the paper conveyance path S, and the transfer roller is aligned with the leading edge of the paper and the leading edge of the image information on the intermediate transfer belt 61. 10 and image information is written on the paper. Thereafter, the paper passes through the fixing unit 7 so that the unfixed toner on the paper is melted and fixed by heat, and is then discharged onto the paper discharge tray 91 through the transport rollers 12b to 12d.

  Next, the functional configuration of the image forming apparatus 100 will be described with reference to FIG. In the image forming apparatus 100, an image reading unit 1020, an image forming unit 1040, a storage unit 1060, an operation unit 1080, and a moving mechanism control unit 1100 are connected to the control unit 1000 via a bus.

  The control unit 1000 is a functional unit that controls the image forming operation of the entire image forming apparatus 100. The control unit 1000 implements various functions by reading and executing a program stored in the storage unit 1060.

  The image reading unit 1020 is a functional unit for reading a document as image data. For example, a document placed on a glass table is read by a CCD (Charge Coupled Device) scanner, converted into image data, and converted. The image data is output to the storage unit 1060.

  The image forming unit 1040 is a functional unit for forming an image on recording paper (photographic paper) based on image data (image data read by the image reading unit 1020) stored in the storage unit 1060.

  The storage unit 1060 is a functional unit that stores various programs necessary for the operation of the image forming apparatus 100 and various data. In addition, image data read by the image reading unit 1020 is stored. Here, the image data may be received by, for example, a communication unit (not shown) in addition to being read from the image reading unit 1020. The storage unit 1060 is configured by, for example, a semiconductor memory, an HDD (Hard Disk Drive), or the like.

  The operation unit 1080 is a functional unit for the user to perform various operations / instructions. For example, an image reading instruction, a printing instruction, or the like can be performed via the operation unit 1080. Here, the operation unit 1080 includes various input devices such as operation buttons and a touch panel.

  In the present embodiment, for example, the movement mechanism control unit 1100 can be instructed in the direction in which the movement mechanism is moved, the amount of movement, and the like. When a movement amount or the like is input from the operation unit 1080, the movement mechanism control unit 1100 controls the movement mechanism based on the input movement amount or the like.

  The moving mechanism control unit 1100 is a functional unit that controls a moving mechanism for controlling the discharge direction of the paper discharged from the fixing unit 7. The paper curls “upward” (that is, curls “right” when the paper is transported vertically in the image forming apparatus 100) or curls “downward” (ie, the paper is The curling amount of the paper is adjusted by controlling the moving mechanism depending on whether the image forming apparatus 100 is curled in the “left direction” when being conveyed in the vertical direction.

  Here, the moving mechanism will be described with reference to FIG. FIG. 3 is a diagram schematically showing a part of the fixing unit 7 and a sheet conveyance path after the fixing unit 7.

  The paper that has passed through the heat roller 71 and the pressure roller 72 of the fixing unit 7 passes through the transport rollers 12b, 12c, and 12d and is discharged. In addition, a conveyance guide 22 is provided between the conveyance roller 12b and the conveyance roller 12d, and a conveyance guide 24 is provided between the conveyance roller 12c and the conveyance roller 12d. Become.

  Here, the moving mechanism control unit 1100 performs control to move the transport roller 12b in the left-right direction. For example, in the case of a sheet curled upward (rightward in FIG. 3), the transport roller 12b is moved leftward as shown in FIG. In this case, the sheet discharged from the fixing unit 7 (the sheet that has passed through the heat roller 71 and the pressure roller 72) is squeezed downward (to the left in FIG. 3) by the transport roller 12b, and the sheet is corrected. Thus, the curl amount is suppressed to be uniform, and the curl amount is uniform as a whole.

  Similarly, when the paper is curled downward (leftward in FIG. 3), the transport roller 12b is moved rightward as shown in FIG. 3C. If the paper is not curled, the transport roller 12b is moved to the center as shown in FIG.

  At this time, the conveyance guide 20 can also be moved and controlled in accordance with the conveyance roller 12b. Thereby, the sheet discharged from the fixing unit 7 can be appropriately sent to the transport roller 12b.

  Thus, since the sheet immediately after passing through the heat roller 71 is heated, it is easily deformed, and the curl amount of the sheet can be effectively adjusted by moving the position of the transport roller 12b.

  Note that the amount of movement of the conveying roller 12b may be provided by a curl amount detection sensor that detects the guide amount of the paper, and may be moved according to the amount of detection by the curl amount detection sensor. The position of the roller 12b may be controlled.

  Moreover, it is good also as providing a movable guide instead of the conveyance roller 12b. That is, as shown in FIG. 4, a movable guide 26 and a switching gate 28 are provided in place of the transport roller 12b. When the paper is curled upward (rightward in FIG. 4) by moving the switching gate 28, the movable guide 26 is raised as shown in FIG. It is controlled so that it is conveyed to the left side of 22. When the paper is curled downward (leftward in FIG. 4), the paper is transported to the right side of the transport guide 22 by laying down the movable guide 26 as shown in FIG. To control.

  If the paper is not curled, as shown in FIG. 4B, the movable guide 26 is adjusted so that the paper enters the transport roller 12c on a substantially straight line, thereby discharging the paper as it is. can do.

  In this way, the conveyance roller or peeling claw immediately after the fixing roller in three directions, straight, close to the heat roller and close to the pressure roller, with respect to the direction in which the paper comes out from the nip of the fixing roller (heat roller and pressure roller). By arranging the (paper guide) and determining the paper traveling direction, it is possible to effectively control the portion having the highest influence on the curl. Even if the direction is changed in the opposite direction after that, the influence is small, so that the whole is influenced by the first curl correction direction.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design and the like within the scope of the present invention are also within the scope of the claims. include.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 1 Exposure unit 2 Developer 3 Photoconductor drum 4 Cleaner unit 5 Charger 6 Intermediate transfer belt unit 7 Fixing unit 10 Transfer roller 11a, 11b Pickup roller 12a, 12b, 12c, 12d Conveyance roller 13 Registration roller 20, 22, 24 Conveyance guide 26 Movable guide 28 Switching gate 61 Intermediate transfer belt 62 Intermediate transfer belt drive roller 63 Intermediate transfer belt driven roller 64 Intermediate transfer roller 65 Intermediate transfer belt cleaning unit 71 Heat roller 72 Pressure roller 73 External fixing belt 81 82 Paper feed cassette 91 Paper discharge tray 92 Document placement table 110 Main body 120 Document processing device 1000 Control unit 1020 Image reading unit 1040 Image forming unit 1060 Storage unit 1080 Operation unit 110 The movement mechanism control unit

Claims (5)

A fixing unit for fixing the toner after transfer to the paper;
A first transport roller for transporting the paper discharged from the fixing unit;
A second transport roller for discharging the paper discharged from the first transport roller;
A moving mechanism control unit that performs control to move the first conveying roller according to the curl direction of the paper;
An image forming apparatus comprising: A conveyance guide between the fixing unit and the first conveyance roller;
The image forming apparatus according to claim 1, wherein the movement mechanism control unit moves the conveyance guide together when the first conveyance roller is moved. An operation unit for instructing and operating the movement amount of the first conveying roller;
The image forming apparatus according to claim 1, wherein the moving mechanism control unit performs control to move the first transport roller based on a moving amount instructed by the operation unit. A fixing unit for fixing the toner after transfer to the paper;
A transport roller for transporting the paper discharged from the fixing unit;
With
A movable guide for suppressing curling of the paper between the fixing unit and the conveying roller;
A moving mechanism control unit for controlling the movable guide according to the curl direction of the paper;
An image forming apparatus comprising: An operation unit for instructing and operating the position of the movable guide;
The image forming apparatus according to claim 4, wherein the moving mechanism control unit performs control to adjust the movable guide based on a position instructed by the operation unit.

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