US20120018947A1 - Image forming apparatus - Google Patents
Image forming apparatus Download PDFInfo
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- US20120018947A1 US20120018947A1 US13/179,636 US201113179636A US2012018947A1 US 20120018947 A1 US20120018947 A1 US 20120018947A1 US 201113179636 A US201113179636 A US 201113179636A US 2012018947 A1 US2012018947 A1 US 2012018947A1
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- United States
- Prior art keywords
- shift
- discharge roller
- discharge
- roller
- sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H33/00—Forming counted batches in delivery pile or stream of articles
- B65H33/06—Forming counted batches in delivery pile or stream of articles by displacing articles to define batches
- B65H33/08—Displacing whole batches, e.g. forming stepped piles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2404/00—Parts for transporting or guiding the handled material
- B65H2404/10—Rollers
- B65H2404/14—Roller pairs
- B65H2404/142—Roller pairs arranged on movable frame
- B65H2404/1424—Roller pairs arranged on movable frame moving in parallel to their axis
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2511/00—Dimensions; Position; Numbers; Identification; Occurrences
- B65H2511/20—Location in space
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2513/00—Dynamic entities; Timing aspects
- B65H2513/10—Speed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2513/00—Dynamic entities; Timing aspects
- B65H2513/40—Movement
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2513/00—Dynamic entities; Timing aspects
- B65H2513/50—Timing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2557/00—Means for control not provided for in groups B65H2551/00 - B65H2555/00
- B65H2557/20—Calculating means; Controlling methods
- B65H2557/24—Calculating methods; Mathematic models
- B65H2557/242—Calculating methods; Mathematic models involving a particular data profile or curve
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2801/00—Application field
- B65H2801/03—Image reproduction devices
- B65H2801/06—Office-type machines, e.g. photocopiers
Abstract
An image forming apparatus (100) includes a rotation driving portion (40) configured to drive rotation of a discharge roller (31), a shift driving portion (50) configured to drive shift of the discharge roller (31), thereby causing shift, and a control portion (200) configured to control driving of rotation of the rotation driving portion (40) and driving of shift of the shift driving portion (50). The control portion (200) controls a discharge timing for sheet (P) that is being discharged such that a trailing edge (P2) of the sheet (P) moves past the discharge roller (31) during the shift of the discharge roller (31).
Description
- This application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2010-166100 filed in Japan on Jul. 23, 2010, the entire contents of which are herein incorporated by reference.
- The present invention relates to an image forming apparatus such as a printer, a copier, and a multifunction peripheral.
- As a conventional image forming apparatus, an apparatus is known that sorts sheets discharged by a discharge roller for discharging sheets such as recording papers to the outside, by causing shift of the discharge roller in the axial direction of the discharge roller (see JP H3-42460A, for example).
- In such an image forming apparatus, when sheet types such as surface smoothnesses or basis weights are different (in particular, when sheets other than designated standard sheets are used), the stack properties of sheets discharged to a sheet discharge tray become poor, and, thus, the sheets are scattered in the sheet discharge tray, resulting in the problem that the sheets cannot be reliably separated and sorted.
- In order to solve this problem, the sorting width of sheets discharged to the sheet discharge tray can be increased by increasing the shift width of the discharge roller, but, at that time, the width of the image forming apparatus in the axial direction of the discharge roller increases.
- Regarding this aspect, JP 2000-153946A discloses a configuration in which, in order to obliquely discharge paper, a pair of discharge rollers for sandwiching and discharging paper are arranged such that they can be brought into contact with or separated from each other on one end side, and the conveying force applied to the paper at the time of paper discharge is applied to only one side.
- Furthermore, JP 2009-069464A discloses a configuration in which, in order to obliquely discharge recording paper, a first and a second discharge roller are arranged in a line along an axis that extends in a direction perpendicular to the recording paper convey direction on the upstream side from the discharge tray, the discharge rollers are driven by mutually independent drive sources, and, thus, the revolving velocity of the first discharge roller is set higher than that of the second discharge roller.
- According to these conventional configurations, the sorting width of discharged sheets can be increased without increasing the width of the image forming apparatus in the axial direction of the discharge roller. However, the mechanical structure of an existing discharge roller portion has to be changed, which accordingly increases the complexity and the cost of the mechanical structure in the image forming apparatus.
- It is an object of the present invention to provide an image forming apparatus that can increase the sorting width of discharged sheets, without increasing the width of the image forming apparatus in the axial direction of a discharge roller, and without changing the mechanical structure of an existing discharge roller portion, and, thus, can reliably separate and sort the sheets.
- In order to solve the above-described problem, according to the present invention, the sorting width of discharged sheets is made larger than the shift amount of a discharge roller for discharging sheets to the outside, by adjusting a paper discharge timing for a sheet that is being discharged from the discharge roller with respect to shift of the discharge roller in the axial direction of the discharge roller.
- That is to say, in order to solve the above-described problem, the present invention is directed to an image forming apparatus that sorts sheets discharged by a discharge roller for discharging sheets to the outside, by causing shift of the discharge roller along an axial direction of the discharge roller, including: a rotation driving portion configured to drive rotation of the discharge roller; a shift driving portion configured to drive shift of the discharge roller, thereby causing the shift; and a control portion configured to control driving of rotation of the rotation driving portion and driving of shift of the shift driving portion; wherein the control portion controls a discharge timing for a sheet that is being discharged such that a discharge direction upstream edge (trailing edge) of the sheet moves past the discharge roller during the shift of the discharge roller.
- According to the present invention, only the control configuration of the control portion is changed, and, thus, the width of the image forming apparatus in the axial direction of the discharge roller is not increased, and the mechanical structure of an existing discharge roller portion is not changed. The control portion controls a discharge timing for a sheet that is being discharged such that the discharge direction upstream edge of the sheet moves past the discharge roller during the shift of the discharge roller, and, thus, the sheet whose upstream edge has moved past the discharge roller is discharged in a direction based not only on a discharge direction vector of the force of inertia in the discharge direction but also on an axial direction vector of the force of inertia in the axial direction. That is to say, the sheet whose upstream edge has moved past the discharge roller is discharged in a direction of a resultant vector obtained by adding the discharge direction vector and the axial direction vector, and, thus, the sheet whose upstream edge has moved past the discharge roller can be discharged to obliquely outer sides with respect to the discharge direction. Therefore, it is possible to increase the sorting width of discharged sheets, and, thus, it is possible to reliably separate and sort the sheets.
- In an example mode of the present invention, the discharge timing at which the discharge direction upstream edge of the sheet that is being discharged moves past the discharge roller during the shift is a timing at which a movement velocity of the shift of the discharge roller is a maximum velocity.
- With this specific mode, when the force of inertia in the axial direction is maximum, the discharge direction upstream edge of the sheet moves past the discharge roller during the shift. Thus, it is possible to accordingly increase the sorting width of discharged sheets.
- In an example mode of the present invention, the discharge timing at which the discharge direction upstream edge of the sheet that is being discharged moves past the discharge roller during the shift is substantially equivalent to a timing at which the discharge roller reaches a movement end in the axial direction.
- With this specific mode, the discharge direction upstream edge of the sheet that is being discharged moves past the discharge roller when the discharge roller reaches the vicinity of a movement end in the shift direction. Thus, it is possible to increase the movement distance in which the discharge roller conveying the sheet is shifted to the extent possible, and, thus, it is possible to accordingly increase the sorting width of discharged sheets.
- Here, in order to improve the image forming speed, it is preferable to improve the sheet conveying velocity, but if the sheet conveying velocity is too large, a sheet pops out from the discharge roller in the discharge direction with too strong force, and, thus, a deterioration in the stack properties of the sheets occurs. From this point of view, the control portion preferably reduces a revolving velocity of the discharge roller before the discharge direction upstream edge of the sheet that is being discharged moves past the discharge roller.
- With this specific mode, it is possible to convey the sheets at a high speed before the discharge direction upstream edge of the sheet that is being discharged moves past the discharge roller, and, thus, it is possible to suppress a deterioration in the stack properties of the sheets while accordingly increasing the image forming speed.
- In an example mode of the present invention, the control portion more preferably reduces the revolving velocity of the discharge roller when starting the shift of the discharge roller.
- With this specific mode, it is possible to prolong the period of time during which the sheets are conveyed at a high speed to the extent possible, and, thus, it is possible to suppress a deterioration in the stack properties of the sheets while accordingly increasing the image forming speed.
- In an example mode of the present invention, the control portion rotates the discharge roller at a first revolving velocity, at a second revolving velocity that is higher than the first revolving velocity after a discharge direction downstream edge (leading edge) of the sheet has moved past the discharge roller, at a third revolving velocity that is higher than the first revolving velocity and lower than the second revolving velocity before the discharge direction upstream edge of the sheet moves past the discharge roller, and again at the first revolving velocity after the discharge direction upstream edge of the sheet has moved past the discharge roller.
- With this specific mode, it is possible to perform efficient discharge timing control in which improvement in the image forming speed and suppression of a deterioration in the stack properties of sheets are well balanced.
- In an example mode of the present invention, the control portion starts the shift of the discharge roller after the discharge direction upstream edge of the sheet that is being discharged has moved past a closest roller disposed closest to the discharge roller on an upstream side therefrom in a discharge direction of the sheet.
- With this specific mode, the shift of the discharge roller is started after the discharge direction upstream edge of the sheet has moved past the closest roller, and, thus, the discharge roller can be shifted in a state where the sheet has been released from the closest roller. Therefore, it is possible to cancel the load by the closest roller on the sheet in the axial direction applied when the discharge roller is shifted, and, thus, it is possible to reduce damage to the sheet.
- In an example mode of the present invention, a timing of starting the shift of the discharge roller can be adjusted.
- With this specific mode, it is possible to change the timing of starting the shift of the discharge roller according to the driving properties of the rotation driving portion and the shift driving portion (e.g., the revolving velocity of the discharge roller driven by the rotation driving portion, or the shift width or the movement velocity of the discharge roller driven by the shift driving portion).
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FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention when viewed from the front. -
FIG. 2 is a schematic cross-sectional view showing a discharge roller in the image forming apparatus shown inFIG. 1 and portions close thereto. -
FIG. 3 is a schematic side view of a sorting configuration in the image forming apparatus shown inFIG. 1 when viewed in a paper discharge direction. -
FIG. 4 is a system block diagram of a control system of the image forming apparatus shown inFIG. 1 . -
FIGS. 5A to 5D are views for illustrating conventional timing control in the sorting configuration shown inFIG. 3 , whereinFIG. 5A is a schematic plan view showing a state in which paper is discharged at a shift end on one side in the shift direction,FIG. 5B is a schematic plan view showing a state in which the paper is discharged at a shift end on the other side in the shift direction,FIG. 5C is a schematic cross-sectional view showing a state in which the paper is discharged at a point in time where a discharge roller shift unit reaches the shift end on the one side in the shift direction or the shift end on the other side, when viewed in the shift direction, andFIG. 5D is a schematic plan view showing the sorting width of paper discharged to a discharge tray and the positional relationship with respect to the discharge roller shift unit. -
FIG. 6 is a timing chart showing a discharge timing according to conventional timing control in the sorting configuration shown inFIG. 3 . -
FIGS. 7A to 7C are views for illustrating timing control of this embodiment in the sorting configuration shown inFIG. 3 , whereinFIG. 7A is a schematic plan view showing a state in which paper is discharged near the shift end on the one side in the shift direction,FIG. 7B is a schematic plan view showing a state in which the paper is discharged near the shift end on the other side in the shift direction X, andFIG. 7C is a schematic cross-sectional view showing a state in which the paper is discharged at a point in time where the discharge roller shift unit reaches the shift end on the one side in the shift direction X or the shift end on the other side, when viewed in the shift direction. -
FIGS. 8A to 8D are views for illustrating timing control of this embodiment in the sorting configuration shown inFIG. 3 , whereinFIGS. 8A and 8B are respectively a schematic plan view and a schematic side view showing a state in which the paper pops out from a nip portion of the discharge roller,FIG. 8C is a schematic side view showing a state in which the paper is placed on the discharge tray, andFIG. 8D is a schematic plan view showing the sorting width of the paper discharged to the discharge tray. -
FIG. 9 is a timing chart showing a discharge timing according to timing control of this embodiment in the sorting configuration shown inFIG. 3 . -
FIG. 10 is a timing chart obtained by adding a chart of the shift velocity of the discharge roller toFIG. 9 . -
FIG. 11 is a timing chart showing a timing substantially equivalent to a timing at which the discharge roller shift unit reaches the shift end on the one side in the shift direction or the shift end on the other side in the configuration shown inFIG. 10 . -
FIG. 12 is a timing chart obtained by adding, toFIG. 11 , timing control that increases the revolving velocity of the discharge roller after the leading edge of the paper has moved past the discharge roller and reduces the revolving velocity of the discharge roller before the trailing edge of the paper moves past the discharge roller. -
FIG. 13 is a timing chart showing a timing at which shift of the discharge roller is started after the trailing edge of the paper has moved past the closest roller disposed closest to the discharge roller on the upstream side therefrom in the discharge direction in the configuration shown inFIG. 12 . -
FIG. 14 is a graph showing the measurement results of an example checking the relationship between the sorting width of the paper and the discharge timing of the paper. - Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are only examples in which the present invention is embodied, and are not intended to limit the technical scope of the present invention.
- (Description of the Overall Configuration of the Image Forming Apparatus)
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FIG. 1 is a schematic cross-sectional view of animage forming apparatus 100 according to an embodiment of the present invention when viewed from the front. - The
image forming apparatus 100 shown inFIG. 1 is a color image forming apparatus that forms multicolor and monochrome images on a sheet P such as recording paper (hereinafter, referred to as “paper”) in response to image data transmitted from the outside. Theimage forming apparatus 100 includes anoriginal reading device 108 and anapparatus body 110, and theapparatus body 110 includes animage forming portion 102 and asheet conveying system 103. - The
image forming portion 102 includes alight exposure unit 1, a plurality ofdevelopment units 2, a plurality ofphotosensitive drums 3, a plurality of cleaning portions 4, a plurality ofchargers 5, an intermediatetransfer belt unit 6, a plurality oftoner cartridge units 21, and afixing unit 7. - Furthermore, the
sheet conveying system 103 includes apaper feed tray 81, a manualpaper feed tray 82, and adischarge tray 91. - An
original placement plate 92 made of transparent glass on which an original (sheet) is placed is provided above theapparatus body 110, and anoptical unit 90 for reading an original is provided below theoriginal placement plate 92. Theoriginal reading device 108 is provided above theoriginal placement plate 92. Theoriginal reading device 108 conveys automatically an original onto theoriginal placement plate 92. Theoriginal reading device 108 is attached pivotally to theapparatus body 110 with the front side openable, and an original can be placed manually after exposing the surface of theoriginal placement place 92. - The
original reading device 108 can read an original automatically conveyed or an original placed on theoriginal placement plate 92. The entire image of the original read by theoriginal reading device 108 is transmitted as image data to theapparatus body 110 of theimage forming apparatus 100, and an image formed based on the image data is recorded on paper P in theapparatus body 110. - The image data that can be processed in the
image forming apparatus 100 is that corresponding to color images using multiple colors (black (K), cyan (C), magenta (M), yellow (Y) in this embodiment). Therefore, for each unit group of thedevelopment units 2, thephotosensitive drums 3, the cleaning portions 4, thechargers 5, and thetoner cartridge units 21, a plurality of units (four in this embodiment, respectively corresponding to black, cyan, magenta and yellow) are provided, such that images of multiple kinds (four kinds in this embodiment) corresponding to four colors can be formed, and accordingly a plurality of image stations (four image stations in this embodiment) are configured. - The
chargers 5 are charging means for uniformly charging the surface ofphotosensitive drums 3 to a predetermined potential, and for thechargers 5, chargers of roller type or brush type, which are contact type, can be used, as well as chargers as shown inFIG. 1 . - The
light exposure unit 1 is configured in a form of a laser scanning unit (LSU) provided with a laser irradiating portion and reflection mirrors. Thelight exposure unit 1 is provided with a polygon mirror scanned by a laser beam, and optical elements such as lenses or mirrors for guiding the laser light reflected by the polygon mirror to thephotosensitive drums 3. For thelight exposure unit 1, other concepts can be used, such as a concept employing a writing head in which optical elements such as EL (electroluminescence) elements or LEDs (light-emitting diodes) are aligned in an array. - The
light exposure unit 1 irradiates thephotosensitive drums 3 that are charged in accordance with input image data with light so that an electrostatic latent image in accordance with the image data is formed on the surfaces of thephotosensitive drums 3. - The
toner cartridge units 21 are units containing toner, and are configured such that the toner is supplied to the development baths of thedevelopment units 2. In theapparatus body 110 of theimage forming apparatus 100, the toner supplied from thetoner cartridge units 21 to the development baths of thedevelopment units 2 is controlled such that the toner concentration of a developer in the development baths is constant. - The
development units 2 make the electrostatic latent images formed on the respectivephotosensitive drums 3 visible with four color toners (Y, M, C, and K). The cleaning portions 4 remove and recover toner that is left on the surfaces of thephotosensitive drums 3 that have undergone development and image transfer. - The intermediate
transfer belt unit 6 arranged above thephotosensitive drums 3 includes anintermediate transfer belt 61 functioning as an intermediate transfer member, an intermediate transferbelt driving roller 62, an intermediate transfer belt idle roller 63, a plurality of intermediate transfer rollers 64, and an intermediate transfer belt cleaning unit 65. - For the intermediate transfer rollers 64, four rollers are provided corresponding respectively to colors Y, M, C, and K. The intermediate transfer
belt driving roller 62 supports theintermediate transfer belt 61 in cooperation with the intermediate transfer belt idle roller 63 and the intermediate transfer rollers 64 such that theintermediate transfer belt 61 is in tension. When the intermediate transferbelt driving roller 62 is driven to rotate, then theintermediate transfer belt 61 is revolved in the movement direction (direction indicated by arrow M inFIG. 1 ), which causes the intermediate transfer belt idle roller 63 and the intermediate transfer rollers 64 to be idly rotated. - The intermediate transfer rollers 64 are supplied with a transfer bias for transferring toner images formed on the
photosensitive drums 3 onto theintermediate transfer belt 61. - The
intermediate transfer belt 61 is provided in such a manner that it is in contact with each of thephotosensitive drums 3. Toner images of the respective colors formed on thephotosensitive drums 3 are sequentially transferred to theintermediate transfer belt 61 so as to be superimposed one after another, so that a color toner image (multicolor toner image) can be formed on the surface of theintermediate transfer belt 61. Theintermediate transfer belt 61 is formed by an endless belt made of a film having a thickness of about 100 μm to 150 μm. - Toner images are transferred from the
photosensitive drums 3 to theintermediate transfer belt 61 by means of the intermediate transfer rollers 64 that are in contact with the back face of theintermediate transfer belt 61. The intermediate transfer rollers 64 are supplied with a high voltage transfer bias (high voltage having an opposite polarity (+) to the polarity (−) of the charged toner) for transferring toner images. Each intermediate transfer roller 64 is made by forming its core with a metal (e.g., stainless steel) shaft having a diameter of 8 mm to 10 mm and covering the surface of the core with a conductive elastic material (e.g., resin materials such as EPDM (ethylene propylene diene rubber) or foamed urethane). The intermediate transfer rollers 64 function as transfer electrodes that apply a high voltage uniformly to theintermediate transfer belt 61 with the conductive elastic material. Although roller-like transfer electrodes are used as the transfer electrodes in this embodiment, other transfer electrodes, for example, brush-like transfer electrodes can be used. - As described above, toner images that are made visible in accordance with the color phases on the respective
photosensitive drums 3 are layered on theintermediate transfer belt 61. The toner images layered on theintermediate transfer belt 61 are transferred onto the paper P by atransfer roller 10 constituting a second transfer mechanism portion disposed in a contact position in which the paper P is in contact with theintermediate transfer belt 61, by means of the rotational movement of theintermediate transfer belt 61. However, as the configuration of the second transfer mechanism portion, not only transfer rollers, but also other transfer configurations such as those employing corona chargers or transfer belts can be used. - At this time, the
transfer roller 10 is supplied with a voltage for transferring toner onto the paper P in a state where a transfer nip is formed between thetransfer roller 10 and theintermediate transfer belt 61. This voltage is a high voltage having an opposite polarity (+) of the polarity (−) of the charged toner. The transfer nip is formed between thetransfer roller 10 and theintermediate transfer belt 61 by thetransfer roller 10 and the intermediate transferbelt driving roller 62 pressing against each other. In order to obtain the transfer nip steadily, either one of thetransfer roller 10 and the intermediate transferbelt driving roller 62 is a hard roller made of a hard material such as metal and the other is an elastic roller made of a soft material such as elastic rubber or foamed resin. - When transferring a toner image from the
intermediate transfer belt 61 onto the paper P with thetransfer roller 10, toner may remain on theintermediate transfer belt 61 without being transferred onto the paper P. - The toner that has remained on the
intermediate transfer belt 61 may cause mixture of colors in subsequent processes. Therefore, the toner that has remained on theintermediate transfer belt 61 is removed and recovered by the intermediate transfer belt cleaning unit 65. More specifically, the intermediate transfer belt cleaning unit 65 is provided with a cleaning member (e.g., a cleaning blade) that is in contact with theintermediate transfer belt 61. The idle roller 63 supports theintermediate transfer belt 61 from the inside (back face side), and the cleaning member is in contact with theintermediate transfer belt 61 so as to press against it toward the idle roller 63 from the outside. - The
paper feed tray 81 is a tray accommodating in advance sheets of the paper P on which an image is to be formed (printed), and is provided below thelight exposure unit 1 in theapparatus body 110. On the manualpaper feed tray 82, sheets of the paper P on which an image is to be formed (printed) are placed. Thedischarge tray 91 is provided above theimage forming portion 102 in theapparatus body 110, and sheets of the paper P on which an image has been formed (printed) are accumulated face-down on thedischarge tray 91. Thedischarge tray 91 is configured such that the upstream side in a discharge direction (direction indicated by arrow Y1 inFIG. 1 ) of aplacement face 91 a on which the paper P is to be placed is lower than the downstream side. - Furthermore, the
apparatus body 110 is provided with a sheet conveying path S for conveying the paper P that has been conveyed from thepaper feed tray 81 or the manualpaper feed tray 82, via thetransfer roller 10 and the fixingunit 7 to thedischarge tray 91. Arranged in the vicinity of the sheet conveying path S arepickup rollers 11 a and lib, a first to a fourth conveyingroller 12 a to 12 d,registration rollers 13, thetransfer roller 10, aheat roller 71 and apressing roller 72 of the fixingunit 7, and adischarge roller 31. - The first to the fourth conveying
rollers 12 a to 12 d are small rollers for promoting and assisting conveying of the paper P, and are provided along the sheet conveying path S. Thepickup roller 11 a is provided in the vicinity of thepaper feed tray 81 on the paper feeding side for picking up the paper P sheet by sheet from thepaper feed tray 81 and feeds the sheets to the sheet conveying path S. Similarly, thepickup roller 11 b is provided in the vicinity of the manualpaper feed tray 82 on the paper feeding side for picking up the paper P sheet by sheet from the manualpaper feed tray 82 and feeds the sheets to the sheet conveying path S. - The
registration rollers 13 temporarily hold the paper P that is being conveyed in the sheet conveying path S. Then, theregistration rollers 13 convey the paper P to thetransfer roller 10 at a timing at which a leading edge of the toner image on thephotosensitive drums 3 is aligned with an edge P1 on the downstream side in the discharge direction Y1 (hereinafter, referred to as a “leading edge”) of the paper P. - The fixing
unit 7 fixes an unfixed toner image onto the paper P, and includes theheat roller 71 and thepressing roller 72 that function as fixing rollers. When being driven to rotate, theheat roller 71 conveys the paper P while sandwiching the paper P along with thepressing roller 72 that is idly rotated. Theheat roller 71 is heated with aheater 71 a provided inside it, and is maintained at a predetermined fixing temperature based on a signal from atemperature detector 71 b. Theheat roller 71 heated with theheater 71 a performs thermo-compression bonding of a multicolor toner image transferred onto the paper P on the paper P along with thepressing roller 72, so that the multicolor toner image is melted, mixed, and pressed and thus is thermo-fixed onto the paper P. The fixingunit 7 is also provided with anexternal heating belt 73 for heating theheat roller 71 from the outside. - In the
image forming apparatus 100 configured in the above described manner, when there is a request for simplex printing on paper P, paper P fed from thepaper feed tray registration rollers 13 by the first conveyingrollers 12 a provided along the sheet conveying path S, and is conveyed by thetransfer roller 10 at a timing at which the leading edge P1 of the paper P is aligned with the leading edge of the toner image on theintermediate transfer belt 61, and then the toner image is transferred onto the paper P. Thereafter, the paper P passes through the fixingunit 7, so that unfixed toner on the paper P is melted by heat and adheres to the paper P, and then the paper P is discharged onto thedischarge tray 91 through the second conveyingrollers 12 b and thedischarge roller 31. - When there is a request for duplex printing on paper P, in a state where an edge P2 on the upstream side in the discharge direction Y1 (hereinafter, referred to as a “trailing edge”) of the paper P that has passed through the fixing
unit 7 is positioned between thedischarge roller 31 and a branching portion Sa on the sheet conveying path S after the simplex printing as described above has completed, thedischarge roller 31 is reversely rotated, so that the paper P is guided to the third and the fourth conveyingrollers registration rollers 13 undergoes printing on its back face, and then is discharged onto thedischarge tray 91. - The
image forming apparatus 100 according to this embodiment is configured such that sheets of the paper P discharged by thedischarge roller 31 are sorted by causing shift of thedischarge roller 31 along the axial direction of thedischarge roller 31. -
FIG. 2 is a schematic cross-sectional view showing thedischarge roller 31 in theimage forming apparatus 100 shown inFIG. 1 and portions close thereto.FIG. 3 is a schematic side view of the sorting configuration in theimage forming apparatus 100 shown inFIG. 1 when viewed in the discharge direction Y1 of the paper P. - As shown in
FIGS. 2 and 3 , theimage forming apparatus 100 includes a dischargeroller shift unit 30 having thedischarge roller 31, arotation driving portion 40, and ashift driving portion 50. - The discharge
roller shift unit 30 is disposed reciprocally movable along the axial direction of the discharge roller 31 (direction indicated by arrow X inFIG. 3 , hereinafter referred to as a “shift direction X”) with respect to theapparatus body 110. More specifically, the dischargeroller shift unit 30 is supported by theapparatus body 110 via a slide member (more specifically, a slide rail) 30 b (seeFIG. 2 ) that can reciprocally move along the shift direction X. Here, theslide member 30 b may have a conventionally known configuration, and a detailed description thereof has been omitted in this specification. - Furthermore, a
body frame 30 a of the dischargeroller shift unit 30 includes adetection piece 30 c that is to be detected by a position detector switch SWp described later. - The
discharge roller 31 is to discharge the paper P to thedischarge tray 91, and, in this example, includes discharge roller pairs 34 consisting of adischarge driving roller 32 and a dischargeidle roller 33. - More specifically, the
discharge driving roller 32 includes a drivingroller shaft 32 a and four drivingroller portions 32 b that are coaxially fixed to the drivingroller shaft 32 a. The dischargeidle roller 33 includesidle roller shafts 33 a and a plurality ofidle roller portions 33 b that are coaxially fixed to theidle roller shafts 33 a in opposition to the drivingroller portions 32 b. Furthermore, thedischarge roller 31 further includes biasing members (in this example, compression springs) 35 that bias theidle roller portions 33 b toward the drivingroller portions 32 b. - The discharge roller pairs 34 and the biasing
members 35 are arranged in thebody frame 30 a of the dischargeroller shift unit 30, and one end portion of thedischarge driving roller 32 is projected from thebody frame 30 a of the dischargeroller shift unit 30 to the outside in the shift direction X. - The driving
roller shaft 32 a of thedischarge driving roller 32 is a single unit in this example, and is disposed axially rotatably with respect to thebody frame 30 a of the dischargeroller shift unit 30. - In this example, two
idle roller shafts 33 a of the dischargeidle roller 33 are arranged side by side along the shift direction X, and twoidle roller portions 33 b are fixed to each shaft. Theidle roller shafts 33 a are arranged such that theidle roller portions 33 b oppose the correspondingdriving roller portions 32 b, can axially rotate with respect to thebody frame 30 a of the dischargeroller shift unit 30, and can reciprocally move in the vertical direction (direction indicated by arrow Z inFIGS. 2 and 3 ). Thedischarge roller 31 is configured such that the paper P is conveyed while being sandwiched in a state where the paper P is pressed by the dischargeidle roller 33 at a nip portion N between thedischarge driving roller 32 and the dischargeidle roller 33. - More specifically, the biasing
members 35 are configured so as to bias the dischargeidle roller 33 toward thedischarge driving roller 32, and, in this example, are arranged between theidle roller shafts 33 a and a side of thebody frame 30 a not facing thedischarge driving roller 32 in the dischargeroller shift unit 30. Here, the pressing force of the biasingmembers 35 applied to the dischargeidle roller 33 toward thedischarge driving roller 32 is a pressure that can convey the paper P properly. - The
rotation driving portion 40 is to drive rotation of thedischarge roller 31, and includes a conveyance driving motor 41 (in this example, a stepping motor) and adrive transmission mechanism 42 that transmits rotational drive from theconveyance driving motor 41 to thedischarge roller 31. - The
conveyance driving motor 41 is disposed in theapparatus body 110 such that arotational shaft 41 a is along the shift direction X. - In this example, the
drive transmission mechanism 42 is configured from a gear train in which a plurality of gears are arranged in a line, and includes adriving gear 42 a, aroller gear 42 b, and anintermediate gear 42 c. - The
driving gear 42 a is coupled to therotational shaft 41 a of theconveyance driving motor 41. Theroller gear 42 b is coupled to an end portion of the drivingroller shaft 32 a projected outward in the shift direction X from thebody frame 30 a of the dischargeroller shift unit 30. Theintermediate gear 42 c is supported rotatably by a rotational shaft 110 a fixed to theapparatus body 110, and is meshed with thedriving gear 42 a and theroller gear 42 b. Here, gear teeth of thedriving gear 42 a, theroller gear 42 b, and theintermediate gear 42 c are formed in the shape of grooves and ridges extending in the shift direction X, and, thus, theroller gear 42 b can slide in the shift direction X in a state where theroller gear 42 b is meshed with theintermediate gear 42 c. The length of theintermediate gear 42 c in the shift direction X is set to a length that allows the movement width of the dischargeroller shift unit 30 in the shift direction X, that is, a length that is obtained by adding the mesh length of the gears and the length corresponding to the shift amount, and is set to a length that does not cause theroller gear 42 b to be detached from theintermediate gear 42 c even when the dischargeroller shift unit 30 reciprocally moves in the shift direction X. - The
shift driving portion 50 is to drive shift of the discharge roller 31 (in this example, the discharge roller shift unit 30), thereby causing shift, and includes a shift driving motor 51 (in this example, a stepping motor) and ashift mechanism 52 that shifts the dischargeroller shift unit 30. - The
shift driving motor 51 is disposed in theapparatus body 110 such that arotational shaft 51 a is along a direction perpendicular to the shift direction X (in this example, vertical direction Z). - In this example, the
shift mechanism 52 is configured from rack-and-pinion gears that convert rotational drive to linear drive, and includes arack gear 52 a that extends along the shift direction X and acylindrical pinion gear 52 b. - An end portion of the
rack gear 52 a in the shift direction X is coupled to an end portion of the dischargeroller shift unit 30. Thepinion gear 52 b is coupled to therotational shaft 51 a of theshift driving motor 51, and is meshed with therack gear 52 a. Accordingly, the dischargeroller shift unit 30 can be reciprocally moved in the shift direction X, by rotating therotational shaft 51 a of theshift driving motor 51 in one direction or the other direction. -
FIG. 4 is a system block diagram of a control system of theimage forming apparatus 100 shown inFIG. 1 . Theimage forming apparatus 100 further includes acontrol portion 200, a first detector switch SW1 (seeFIG. 2 ), a second detector switch SW2 (seeFIG. 2 ), and the position detector switch SWp (FIGS. 2 and 3 ). - As shown in
FIG. 4 , thecontrol portion 200 includes aprocessing unit 210 such as a CPU, and astorage portion 220 provided with a ROM (read only memory), a RAM (random access memory), and a rewritable non-volatile memory. The ROM can store a control program indicating the procedure of processing that is to be executed by theprocessing unit 210. The RAM can provide a work area for operations. The non-volatile memory can back up and hold data necessary for control, and hold and rewrite various types of data (e.g., control time period of timing control described later, etc.). - The
control portion 200 is configured so as to perform timing control of therotation driving portion 40 and theshift driving portion 50, as timing control in the sorting configuration of theimage forming apparatus 100. - The first detector switch SW1 is to detect whether or not the paper P is passing through the
discharge roller 31, and, in this example, is disposed in the vicinity of the upstream side from thedischarge roller 31 in the discharge direction Y1. The first detector switch SW1 is electrically connected to the input system of thecontrol portion 200 such that a paper non-passing signal indicating that the paper P is not passing through the discharge roller 31 (in this example, an OFF signal) or a paper passing signal indicating that the paper P is passing through the discharge roller 31 (in this example, an ON signal) can be transmitted to thecontrol portion 200. - The second detector switch SW2 is to detect whether or not the paper P is passing through closest rollers (in this example, the second conveying
rollers 12 b) arranged closest to thedischarge roller 31 on the upstream side therefrom in the discharge direction Y1, and, in this example, is disposed in the vicinity of the downstream side from theclosest rollers 12 b in the discharge direction Y1. The second detector switch SW2 is electrically connected to the input system of thecontrol portion 200 such that a paper non-passing signal indicating that the paper P is not passing through theclosest rollers 12 b (in this example, an OFF signal) or a paper passing signal indicating that the paper P is passing through theclosest rollers 12 b (in this example, an ON signal) can be transmitted to thecontrol portion 200. - The position detector switch SWp detects whether or not the discharge
roller shift unit 30 is positioned at a reference position. More specifically, the reference position is a center position in the shift direction X (standard position at which sorting is not performed). The position detector switch SWp includes, in this example, a transmission-type optical sensor that detects thedetection piece 30 c disposed in thebody frame 30 a of the discharge roller shift unit 30 (seeFIGS. 2 and 3 ). The position detector switch SWp is electrically connected to the input system of thecontrol portion 200 such that a unit presence signal indicating that the dischargeroller shift unit 30 is positioned at the reference position (in this example, an OFF signal) or a unit absence signal indicating that the dischargeroller shift unit 30 is not positioned at the reference position (in this example, an ON signal) can be transmitted to thecontrol portion 200. - The
conveyance driving motor 41 and theshift driving motor 51 are electrically connected to the output system of thecontrol portion 200 such that the drive signal (ON signal) or the drive stopping signal (OFF signal) from thecontrol portion 200 can be obtained. - More specifically, the
control portion 200 drives theconveyance driving motor 41 by transmitting to theconveyance driving motor 41 a rotation instructing signal to instruct the motor to rotate in one direction (i.e., the direction in which the paper P is discharged, indicated by arrow A inFIG. 2 ), and, thus, can drive rotation of thedischarge roller 31 in the one direction A. Here, in this example, thecontrol portion 200 is configured so as to instruct theconveyance driving motor 41 to rotate also in the direction opposite the one direction A in the case of duplex printing, but this aspect does not directly relate to the control in the sorting configuration of theimage forming apparatus 100, and, thus, a description thereof has been omitted. - Furthermore, the
control portion 200 pulse-drives theshift driving motor 51 using the reference position as a reference by transmitting to theshift driving motor 51 a movement instructing signal to instruct the motor to rotate to move the dischargeroller shift unit 30 toward one side in the shift direction X (a leftward direction X1 inFIG. 3 ) and to rotate to move the dischargeroller shift unit 30 toward the other side in the shift direction X (a rightward direction X2 inFIG. 3 ), and, thus, can drive shift of the dischargeroller shift unit 30 in the direction X1 on one side and the direction X2 on the other side. - With the above-described sorting configuration, the
conveyance driving motor 41 is driven in response to the rotation instructing signal from thecontrol portion 200, and, thus, the driving force from theconveyance driving motor 41 is transmitted to thedrive transmission mechanism 42. Accordingly, thedischarge roller 31 is driven to rotate in the one direction A. Furthermore, theshift driving motor 51 is driven in response to the movement instructing signal from thecontrol portion 200, and, thus, the driving force from theshift driving motor 51 is transmitted to theshift mechanism 52. Accordingly, the dischargeroller shift unit 30 is shifted in the direction X1 on one side or the direction X2 on the other side. -
FIGS. 5A to 5D are views for illustrating conventional timing control in the sorting configuration shown inFIG. 3 .FIG. 5A is a schematic plan view showing a state in which the paper P is discharged at a shift end (movement end) on one side in the shift direction X.FIG. 5B is a schematic plan view showing a state in which the paper P is discharged at a shift end (movement end) on the other side in the shift direction X.FIG. 5C is a schematic cross-sectional view showing a state in which the paper P is discharged at a point in time where the dischargeroller shift unit 30 reaches a shift end a on one side in the shift direction X or a shift end β on the other side, when viewed in the shift direction X.FIG. 5D is a schematic plan view showing a sorting width Sa of the paper P discharged to thedischarge tray 91 and the positional relationship with respect to the dischargeroller shift unit 30. -
FIG. 6 is a timing chart showing a discharge timing according to conventional timing control in the sorting configuration shown inFIG. 3 . - As shown in
FIGS. 5A to 5D and 6, in conventional timing control in the sorting configuration shown inFIG. 3 , at a point in time where the dischargeroller shift unit 30 has reached the shift end (see α inFIG. 5A ) on one side in the shift direction X or the shift end (see β inFIG. 5B ) on the other side and shift has completed, the paper P is sandwiched in the discharge roller 31 (seeFIG. 5C ). - That is to say, when sorting sheets of the paper P onto one side (the left in the drawings) in the shift direction X or the other side (the right in the drawings), after it has been recognized that the
discharge roller 31 is sandwiching the paper P with the paper passing signal input from the first detector switch SW1, the dischargeroller shift unit 30 starts movement to the shift end a on one side in the shift direction X or the shift end β on the other side. Then, after shift of the dischargeroller shift unit 30 to the shift end a on one side in the shift direction X or the shift end β on the other side has completed (stopped) (see γ1 inFIG. 6 ), the paper P is discharged (see γ2 inFIG. 6 ). - In this manner, in conventional timing control in the sorting configuration shown in
FIG. 3 , the sorting width Sa (seeFIG. 5D , more specifically, 30 mm) of the paper P discharged to thedischarge tray 91 is equivalent to a shift amount L (seeFIG. 5D , more specifically, 30 mm) of the dischargeroller shift unit 30 in the shift direction X. Here, the dischargeroller shift unit 30 moves from the center position in the shift direction X (standard position at which sorting is not performed) by L/2 on each side, that is, the total shift amount is L consisting of the shift amount L/2 on one side and the shift amount L/2 on the other side. - On the other hand, in this embodiment, the
control portion 200 is configured so as to perform timing control of therotation driving portion 40 and theshift driving portion 50 such that the trailing edge P2 of the paper P that is being discharged passes through thedischarge roller 31 during the shift of thedischarge roller 31. -
FIGS. 7A to 7C and 8A to 8D are explanatory views for illustrating timing control of this embodiment in the sorting configuration shown inFIG. 3 . -
FIG. 7A is a schematic plan view showing a state in which the paper P is discharged near the shift end α on one side in the shift direction X.FIG. 7B is a schematic plan view showing a state in which the paper P is discharged near the shift end β on the other side in the shift direction X.FIG. 7C is a schematic cross-sectional view showing a state in which the paper P is discharged at a point in time where the dischargeroller shift unit 30 has reached the shift end a on one side in the shift direction X or the shift end β on the other side, when viewed in the shift direction X. -
FIGS. 8A and 8B are respectively a schematic plan view and a schematic side view showing a state in which the paper P pops out from the nip portion N of thedischarge roller 31.FIG. 8C is a schematic side view showing a state in which the paper P is placed on thedischarge tray 91.FIG. 8D is a schematic plan view showing a sorting width Sb of the paper P discharged to thedischarge tray 91. -
FIG. 9 is a timing chart showing a discharge timing according to timing control of this embodiment in the sorting configuration shown inFIG. 3 . - As shown in
FIGS. 7A to 9 , in the timing control of this embodiment in the sorting configuration shown inFIG. 3 , at a point in time where the dischargeroller shift unit 30 has reached the shift end (see α inFIG. 7A ) on one side in the shift direction X or the shift end (see β inFIG. 7B ) on the other side and shift has completed, the trailing edge P2 of the paper P in the discharge direction Y1 has been released (detached) from the discharge roller 31 (seeFIG. 7C ). - That is to say, when sorting sheets of the paper P onto one side (the left in the drawings) in the shift direction X or the other side (the right in the drawings), after it has been recognized that the
discharge roller 31 is sandwiching the paper P with the paper passing signal input from the first detector switch SW1, the dischargeroller shift unit 30 moves to the shift end α on one side in the shift direction X or the shift end β on the other side. In this case, before shift of the dischargeroller shift unit 30 to the shift end α on one side in the shift direction X or theshift end 13 on the other side has completed (stopped) (see γ1 inFIG. 9 ), the paper P is discharged (see γ2 inFIG. 9 ). - Then, before the discharge
roller shift unit 30 stops at the shift end α on one side in the shift direction X or the shift end β on the other side, the trailing edge P2 of the paper P is detached from the nip portion N of thedischarge roller 31, and the paper P pops out from the nip portion N of thedischarge roller 31 to an obliquely outer left side Y1 a or an obliquely outer right side Y1 b with respect to the discharge direction Y1 due to the force of inertia in the discharge direction Y1 and the force of inertia on one side X1 in the shift direction X or the other side X2 (seeFIGS. 8A and 8B ). Subsequently, due to inclination of the placement face 91 a of the paper P in thedischarge tray 91, sheets of the paper P return on the placement face 91 a in a direction Y2 opposite the discharge direction Y1 (seeFIG. 8C ), and are aligned in the discharge direction Y1 by a wall face (in this example, a discharge tray end face 91 b) provided upright at the rear end of the discharge tray 91 (seeFIG. 8D ). - In this manner, in the timing control of this embodiment in the sorting configuration shown in
FIG. 3 , the sorting width Sb (more specifically, 45 mm) of the paper P discharged to thedischarge tray 91 can be made larger than the shift amount L of the dischargeroller shift unit 30 in the shift direction X (i.e., the sorting width Sa (more specifically, 30 mm) according to conventional timing control, seeFIG. 5D ), without increasing the shift amount L (more specifically, 30 mm) in the shift direction X (seeFIG. 8D ). - In particular, in the case of the paper P having a large coefficient of surface friction, sheets of the paper P may be placed in a scattered manner on the
discharge tray 91, but, even in this case, bundles of the paper P can be easily distinguished from each other because the sorting width Sb can be increased. - According to the timing control of this embodiment described above, only the control configuration of the
control portion 200 is changed, and, thus, the width of theimage forming apparatus 100 in the shift direction X does not have to be increased, and the mechanical structure of the existingdischarge roller 31 does not have to be changed. Thus, an increase in the complexity and the cost of the mechanical structure of theimage forming apparatus 100 can be suppressed. - Furthermore, the
control portion 200 performs timing control of therotation driving portion 40 and theshift driving portion 50 such that the trailing edge P2 of the paper P that is being discharged passes through thedischarge roller 31 during the shift of thedischarge roller 31. Accordingly, the paper P whose trailing edge P2 has passed through thedischarge roller 31 is discharged in a direction of a resultant vector obtained by adding the discharge direction vector and the shift direction vector. Thus, the paper P whose trailing edge P2 has passed through thedischarge roller 31 can be discharged to the obliquely outer sides Y1 a and Y1 b with respect to the discharge direction Y1. Therefore, the sorting width Sb of the paper P discharged to thedischarge tray 91 can be increased, and, thus, sheets of the paper P can be reliably separated and sorted. - In this embodiment, the
control portion 200 is preferably configured such that the discharge timing at which the trailing edge P2 of the paper P that is being discharged passes through thedischarge roller 31 during the shift is a timing at which a shift velocity Vs (seeFIG. 10 ) of thedischarge roller 31 is a maximum velocity Vsmax. -
FIG. 10 is a timing chart obtained by adding a chart of the shift velocity Vs of thedischarge roller 31 toFIG. 9 . - As shown in
FIG. 10 , the configuration is adopted in which, when the trailing edge P2 of the paper P that is being discharged passes through thedischarge roller 31 during the shift, the shift velocity Vs of thedischarge roller 31 is the maximum velocity Vsmax (more specifically, 140 mm/s). - With this configuration, when the force of inertia on one side X1 in the shift direction X or the other side X2 is the largest, the trailing edge P2 of the paper P passes through the
discharge roller 31 during the shift, and, thus, it is possible to accordingly increase the sorting width of discharged sheets. - Instead of or in addition to the configuration shown in
FIG. 10 , thecontrol portion 200 is preferably configured such that the discharge timing at which the trailing edge P2 of the paper P that is being discharged passes through thedischarge roller 31 during the shift is substantially equivalent to a timing at which the dischargeroller shift unit 30 reaches the shift end α (seeFIG. 7A ) on one side in the shift direction X or the shift end β (seeFIG. 7B ) on the other side. -
FIG. 11 shows a timing substantially equivalent to a timing at which the dischargeroller shift unit 30 reaches the shift end α on one side in the shift direction X or the shift end β on the other side in the configuration shown inFIG. 10 . - As shown in
FIG. 11 , the configuration is adopted in which, when the trailing edge P2 of the paper P that is being discharged passes through thedischarge roller 31 during the shift, the dischargeroller shift unit 30 reaches the vicinity of the shift end α on one side in the shift direction X or the shift end β on the other side (in this example, an end position γ4 in a maximum velocity period γ3 of the shift velocity Vs of the discharge roller 31). - With this configuration, when the discharge
roller shift unit 30 reaches the vicinity of the shift end α on one side in the shift direction X or the shift end β on the other side, the trailing edge P2 of the paper P that is being discharged passes through thedischarge roller 31. Thus, the movement distance by which thedischarge roller 31 conveying the paper P is shifted can be increased to the extent possible. Accordingly, the sorting width Sb of the discharged paper P can be increased. Here, a deceleration period γ5 from the end position γ4 in the maximum velocity period γ3 of the shift velocity Vs of thedischarge roller 31 is reduced to the extent possible, and, thus, the sorting width Sb can be further increased. - Instead of or in addition to the configuration shown in
FIG. 11 , thecontrol portion 200 is preferably configured such that a revolving velocity Vr of thedischarge roller 31 is reduced after the leading edge P1 of the paper P that is being discharged has passed through thedischarge roller 31 and before the trailing edge P2 passes through thedischarge roller 31, more specifically, such that the revolving velocity of the discharge roller is reduced when shift of thedischarge roller 31 is started. -
FIG. 12 shows a timing chart obtained by adding, toFIG. 11 , timing control that increases the revolving velocity Vr of thedischarge roller 31 after the leading edge P1 of the paper P has passed through thedischarge roller 31, and reduces the revolving velocity Vr of thedischarge roller 31 before the trailing edge P2 of the paper P passes through thedischarge roller 31. - As shown in
FIG. 12 , thecontrol portion 200 is configured so as to rotate thedischarge roller 31 at a first revolving velocity Vr1 (more specifically, 140 mm/s), at a second revolving velocity Vr2 (more specifically, 500 mm/s) that is higher than the first revolving velocity Vr1 after the leading edge P1 of the paper P has passed through thedischarge roller 31, at a third revolving velocity Vr3 (more specifically, 186 mm/s) that is higher than the first revolving velocity Vr1 and lower than the second revolving velocity Vr2 before the trailing edge P2 of the paper P passes through the discharge roller 31 (in this example, when shift of thedischarge roller 31 is started), and again at the first revolving velocity Vr1 after the trailing edge P2 of the paper P has passed through thedischarge roller 31. - In the configuration shown in
FIG. 12 , the revolving velocity Vr of thedischarge roller 31 is increased after the leading edge P1 of the paper P that is being discharged has passed through thedischarge roller 31, the revolving velocity Vr of thedischarge roller 31 is reduced before the trailing edge P2 passes through thedischarge roller 31, and, thus, it is possible to convey the paper P at a high speed before the trailing edge P2 of the paper P passes through thedischarge roller 31, and it is possible to suppress a deterioration in the stack properties of the paper P while accordingly increasing the image forming speed. - Furthermore, the revolving velocity Vr of the
discharge roller 31 is reduced when shift of thedischarge roller 31 is started. Thus, it is possible to prolong the period of time during which the sheets are conveyed at a high speed to the extent possible, and it is possible to suppress a deterioration in the stack properties of the paper P while accordingly increasing the image forming speed. - Furthermore, the
discharge roller 31 is rotated basically at the first revolving velocity Vr1 when the paper P is not passing through the discharge roller. Thus, it is possible to reduce the power consumption of theconveyance driving motor 41, and realize a longer life. Moreover, thedischarge roller 31 is rotated at the second revolving velocity Vr2 that is higher than the first revolving velocity Vr1 after the leading edge P1 of the paper P has passed through thedischarge roller 31. Thus, it is possible to convey the paper P at a speed higher than the first revolving velocity Vr1, and it is possible to accordingly increase the image forming speed. Furthermore, thedischarge roller 31 is rotated at the third revolving velocity Vr3 that is higher than the first revolving velocity Vr1 and lower than the second revolving velocity Vr2 before the trailing edge P2 of the paper P passes through thedischarge roller 31. Thus, it is possible to accordingly suppress a deterioration in the stack properties of the paper P. Therefore, it is possible to perform efficient discharge timing control in which improvement in the image forming speed and suppression of a deterioration in the stack properties of the paper P are well balanced. - Instead of or in addition to the configuration shown in
FIG. 12 , thecontrol portion 200 is preferably configured such that shift of thedischarge roller 31 is started after the trailing edge P2 of the paper P has passed through theclosest rollers 12 b. -
FIG. 13 shows a timing at which shift of thedischarge roller 31 is started after the trailing edge P2 of the paper P has passed through theclosest rollers 12 b disposed closest to thedischarge roller 31 on the upstream side therefrom in the discharge direction Y1 in the configuration shown inFIG. 12 . - As shown in
FIG. 13 , the configuration is adopted in which shift of thedischarge roller 31 is started after the trailing edge P2 of the paper P has passed through theclosest rollers 12 b. More specifically, thecontrol portion 200 starts shift of thedischarge roller 31 after recognizing that theclosest rollers 12 b are not sandwiching the paper P with the paper non-passing signal input from the second detector switch SW2. - With this configuration, the
discharge roller 31 can be shifted in a state where the paper P has been released from theclosest rollers 12 b. Therefore, it is possible to cancel the load by theclosest rollers 12 b on the paper P in the shift direction X applied when thedischarge roller 31 is shifted, and, thus, it is possible to reduce damage to the paper P. - Instead of or in addition to the configuration shown in
FIG. 13 , thecontrol portion 200 is preferably configured such that the timing of starting the shift of thedischarge roller 31 can be adjusted. - The timing of starting the shift of the
discharge roller 31 can be adjusted by adjusting a shift start time Tc (seeFIG. 13 ) from when the leading edge P1 of the paper P passes through thedischarge roller 31 to when shift of thedischarge roller 31 is started. The shift start time Tc can be adjusted as appropriate via a setting screen such as a service simulation screen (not shown) using the relationship with a time Ta for the paper P to pass through thedischarge roller 31 and a time Tb for the dischargeroller shift unit 30 to be shifted (Ta>Tc>(Ta−Tb)). Here, the shift start time Tc is stored in a non-volatile memory, and the data is rewritten when being changed. Furthermore, the shift start time Tc may be adjusted by a user operating a setting screen of a user simulation or the like. - With this configuration, it is possible to change the timing of starting the shift of the
discharge roller 31 according to the driving properties of theconveyance driving motor 41 and the shift driving motor 51 (e.g., the revolving velocity Vr of thedischarge roller 31, or the shift width or the shift velocity Vs of the discharge roller 31). - Here, in this embodiment, the configuration is adopted in which switching between a discharge operation of the
discharge roller 31 at the reference position and a discharge operation in the sorting width Sb is possible. However, this is not a limitation, and the configuration may be adopted in which switching to a conventional discharge operation in the shift width of thedischarge roller 31 is also possible. Furthermore, in this embodiment, a sorting operation in which a discharge operation in the sorting width Sb and a discharge operation of thedischarge roller 31 at the reference position are combined may be performed, and a sorting operation in which a discharge operation in the sorting width Sb and a conventional discharge operation in the shift width of thedischarge roller 31 are combined may be performed. Furthermore, a sorting operation in which a discharge operation in the sorting width Sb, a discharge operation of thedischarge roller 31 at the reference position, and a conventional discharge operation in the shift width of thedischarge roller 31 are combined may be also performed. - A research was conducted on the relationship between the sorting width Sb of the paper P and the discharge timing of the paper P. Hereinafter, the research results will be described.
- In this example, in the
image forming apparatus 100, the third revolving velocity Vr3 of thedischarge roller 31 was set to 186 mm/s, and the maximum velocity Vsmax of the shift velocity Vs of thedischarge roller 31 was set to 140 mm/s. Thedischarge roller 31 was decelerated from a point 4.5 mm short of the shift ends α and β. The shift amount L of the dischargeroller shift unit 30 in the shift direction X was set to 30 mm (15 mm on each side from the center position in the shift direction X), plain paper for color printing was used as the paper P, and the sorting width Sb of the paper P discharged to thedischarge tray 91 was measured while changing the discharge timing of the paper P. - Table 1 and
FIG. 14 show the measurement results. Here, in Table 1 andFIG. 14 , a time T and a distance L for discharge timing of the paper P indicate a time and a distance for the dischargeroller shift unit 30 to reach the shift ends α and β at a timing at which the trailing edge P2 of the paper P passes through (moves out of thedischarge roller 31. Thus, at the value “0 ms” of the discharge timing of the paper P, the trailing edge P2 of the paper P moves out of thedischarge roller 31 at a timing at which the dischargeroller shift unit 30 reaches the shift end α or β. Here, the time elapsed from when the dischargeroller shift unit 30 reaches the shift end α or β to when the trailing edge P2 of the paper P moves out of thedischarge roller 31 is indicated in a negative value as the time T. - As shown in Table 1 and
FIG. 14 , according to the configuration in which the trailing edge P2 of the paper P passes through thedischarge roller 31 during the shift when reaching the end position γ4 in the maximum velocity period γ3 of the shift velocity Vs of the discharge roller 31 (seeFIG. 12 ), the sorting width Sb, which had been conventionally 30 mm, was increased to 45 mm. - The present invention can be embodied and practiced in other different forms without departing from the spirit and essential characteristics thereof. Therefore, the above-described embodiments are considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description. All variations and modifications falling within the equivalency range of the appended claims are intended to be embraced therein.
Claims (18)
1. An image forming apparatus that sorts sheets discharged by a discharge roller for discharging sheets to the outside, by causing shift of the discharge roller along an axial direction of the discharge roller, comprising:
a rotation driving portion configured to drive rotation of the discharge roller;
a shift driving portion configured to drive shift of the discharge roller, thereby causing the shift; and
a control portion configured to control driving of rotation of the rotation driving portion and driving of shift of the shift driving portion;
wherein the control portion controls a discharge timing for a sheet that is being discharged such that a discharge direction upstream edge of the sheet moves past the discharge roller during the shift of the discharge roller.
2. The image forming apparatus according to claim 1 , wherein the discharge timing at which the discharge direction upstream edge of the sheet that is being discharged moves past the discharge roller during the shift is a timing at which a movement velocity of the shift of the discharge roller is a maximum velocity.
3. The image forming apparatus according to claim 1 , wherein the discharge timing at which the discharge direction upstream edge of the sheet that is being discharged moves past the discharge roller during the shift is substantially equivalent to a timing at which the discharge roller reaches a movement end in the axial direction.
4. The image forming apparatus according to claim 1 , wherein the control portion reduces a revolving velocity of the discharge roller before the discharge direction upstream edge of the sheet that is being discharged moves past the discharge roller.
5. The image forming apparatus according to claim 4 , wherein the control portion reduces the revolving velocity of the discharge roller when starting the shift of the discharge roller.
6. The image forming apparatus according to claim 4 , wherein the control portion rotates the discharge roller at a first revolving velocity, at a second revolving velocity that is higher than the first revolving velocity after a discharge direction downstream edge of the sheet has moved past the discharge roller, at a third revolving velocity that is higher than the first revolving velocity and lower than the second revolving velocity before the discharge direction upstream edge of the sheet moves past the discharge roller, and again at the first revolving velocity after the discharge direction upstream edge of the sheet has moved past the discharge roller.
7. The image forming apparatus according to claim 1 , wherein the control portion starts the shift of the discharge roller after the discharge direction upstream edge of the sheet that is being discharged has moved past a closest roller disposed closest to the discharge roller on an upstream side therefrom in a discharge direction of the sheet.
8. The image forming apparatus according to claim 1 , wherein a timing of starting the shift of the discharge roller can be adjusted.
9. The image forming apparatus according to claim 2 , wherein the control portion starts the shift of the discharge roller after the discharge direction upstream edge of the sheet that is being discharged has moved past a closest roller disposed closest to the discharge roller on an upstream side therefrom in a discharge direction of the sheet.
10. The image forming apparatus according to claim 3 , wherein the control portion starts the shift of the discharge roller after the discharge direction upstream edge of the sheet that is being discharged has moved past a closest roller disposed closest to the discharge roller on an upstream side therefrom in a discharge direction of the sheet.
11. The image forming apparatus according to claim 4 , wherein the control portion starts the shift of the discharge roller after the discharge direction upstream edge of the sheet that is being discharged has moved past a closest roller disposed closest to the discharge roller on an upstream side therefrom in a discharge direction of the sheet.
12. The image forming apparatus according to claim 5 , wherein the control portion starts the shift of the discharge roller after the discharge direction upstream edge of the sheet that is being discharged has moved past a closest roller disposed closest to the discharge roller on an upstream side therefrom in a discharge direction of the sheet.
13. The image forming apparatus according to claim 6 , wherein the control portion starts the shift of the discharge roller after the discharge direction upstream edge of the sheet that is being discharged has moved past a closest roller disposed closest to the discharge roller on an upstream side therefrom in a discharge direction of the sheet.
14. The image forming apparatus according to claim 2 , wherein a timing of starting the shift of the discharge roller can be adjusted.
15. The image forming apparatus according to claim 3 , wherein a timing of starting the shift of the discharge roller can be adjusted.
16. The image forming apparatus according to claim 4 , wherein a timing of starting the shift of the discharge roller can be adjusted.
17. The image forming apparatus according to claim 5 , wherein a timing of starting the shift of the discharge roller can be adjusted.
18. The image forming apparatus according to claim 6 , wherein a timing of starting the shift of the discharge roller can be adjusted.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010-166100 | 2010-07-23 | ||
JP2010166100A JP5047339B2 (en) | 2010-07-23 | 2010-07-23 | Image forming apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
US20120018947A1 true US20120018947A1 (en) | 2012-01-26 |
Family
ID=45492963
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/179,636 Abandoned US20120018947A1 (en) | 2010-07-23 | 2011-07-11 | Image forming apparatus |
Country Status (3)
Country | Link |
---|---|
US (1) | US20120018947A1 (en) |
JP (1) | JP5047339B2 (en) |
CN (1) | CN102344050B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU2014225609B2 (en) * | 2013-03-07 | 2016-05-19 | Apple Inc. | Room and program responsive loudspeaker system |
US20170108815A1 (en) * | 2015-10-19 | 2017-04-20 | Sharp Kabushiki Kaisha | Sheet discharge device and image forming apparatus including the same |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP7085113B2 (en) * | 2018-02-27 | 2022-06-16 | 株式会社リコー | Sheet transfer device, automatic document transfer device, image reading device and image forming device |
JP7300829B2 (en) | 2018-12-28 | 2023-06-30 | キヤノンファインテックニスカ株式会社 | sheet processing equipment |
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JPH082773A (en) * | 1994-06-17 | 1996-01-09 | Fuji Xerox Co Ltd | Paper discharger for image forming device |
JPH08208098A (en) * | 1995-02-07 | 1996-08-13 | Fuji Xerox Co Ltd | Paper sheet delivery device |
JPH11255390A (en) * | 1998-03-09 | 1999-09-21 | Matsushita Electric Ind Co Ltd | Paper emerging device |
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- 2011-07-21 CN CN201110212284.7A patent/CN102344050B/en active Active
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US20170108815A1 (en) * | 2015-10-19 | 2017-04-20 | Sharp Kabushiki Kaisha | Sheet discharge device and image forming apparatus including the same |
US10087030B2 (en) * | 2015-10-19 | 2018-10-02 | Sharp Kabushiki Kaisha | Sheet discharge device and image forming apparatus including the same |
US20190010007A1 (en) * | 2015-10-19 | 2019-01-10 | Sharp Kabushiki Kaisha | Sheet discharge device and image forming apparatus including the same |
US10676306B2 (en) * | 2015-10-19 | 2020-06-09 | Sharp Kabushiki Kaisha | Sheet discharge device and image forming apparatus including the same |
Also Published As
Publication number | Publication date |
---|---|
CN102344050A (en) | 2012-02-08 |
JP2012025545A (en) | 2012-02-09 |
JP5047339B2 (en) | 2012-10-10 |
CN102344050B (en) | 2014-07-02 |
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Owner name: SHARP KABUSHIKI KAISHA, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KIMURA, MASAHARU;FUJITA, MASAHIKO;AOKI, KOHJI;AND OTHERS;REEL/FRAME:026570/0176 Effective date: 20110617 |
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