Patent Application
20130243511
The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2012-055961 filed in Japan on Mar. 13, 2012.
1. Field of the Invention
The present invention generally relates to a sheet processing device and an image forming system that includes the sheet processing device and an image forming apparatus.
2. Description of the Related Art
Devices, which are called as sheet processing devices, that automatically perform sheet processing such as alignment, stapling, and/or punching on sheets on which images are formed have been widely known. Image forming systems that include an image forming apparatus and this type of sheet processing device connected to the downstream of the image forming apparatus are widely used in recent years. Such a sheet processing device performs sheet finishing, e.g., stacking and stapling. Stacking is a process of stacking sheets on an eject tray while sorting the sheets into sets of sheets. Stapling is a process of stapling each sheet bundle made up of a predetermined number of sheets and stacking the sheet bundles on a stack tray.
Known examples of this type of technique are disclosed in Japanese Patent Application Laid-open No. 9-175724 and Japanese Patent Application Laid-open No. 2007-31095. Specifically, Japanese Patent Application Laid-open No. 9-175724 discloses a sheet finisher that receives printed sheets ejected from an image forming apparatus and distributes the sheets onto a plurality of bins and staples each sheet bundle on the bins. The sheet finisher includes a chuck device that advances toward a trailing-edge center portion of the sheet bundle distributed on one of the bins, chucks the trailing-edge center portion, and conveys the sheet bundle to a stapler located to the rear of the bin. The chuck device performs this operation for each of the bins. The chuck device includes a chucker that clamps the trailing-edge center portion of the sheet bundle loaded on the inclined bin and a moving unit that moves the sheet bundle clamped by the chucker to the stapler disposed on a downstream extension of the sheet bundle.
Japanese Patent Application Laid-open No. 2007-31095 discloses a sheet finisher that performs postprocessing on sheets. The sheet finisher includes a hole puncher (lateral-hole punching unit) that punches holes for use in sheet binding (hereinafter, “binding holes”) in predetermined positions of sheets. The hole puncher, which is movable, moves to binding-hole positions and punches the binding holes. According to this technique, a line connecting the binding holes punched by the lateral-hole punching unit is parallel to a sheet conveying direction. The lateral-hole punch, which is movable, moves to the binding-hole positions and punches the binding holes.
However, the technique disclosed in Japanese Patent Application Laid-open No. 9-175724 is disadvantageous in that the sheet bundle is not moved up and down. This is because although the sheet bundle clamped by the chucker is movable in a conveying direction, the sheet bundle is unmovable in the vertical direction. The sheet finisher disclosed in Japanese Patent Application Laid-open No. 2007-31095 has disadvantageously complicated structure to allow the punching unit to move when punching the binding holes. In addition, a large driving source is necessary to move the punching unit.
Therefore, there is a need to provide a sheet processing device capable of moving sheets with a simple structure without using a large driving source, thereby achieving miniaturization.
It is an object of the present invention to at least partially solve the problems in the conventional technology.
According to an embodiment, there is provided a sheet processing device that includes a clamp configured to clamp an edge portion of a sheet, the edge portion being on a side of an edge parallel to a direction in which the sheet has been conveyed; a first processing unit configured to perform a first process on the sheet at the side of the edge, the first processing unit being disposed at a first position; a second processing unit configured to perform a second process on the sheet at the side of the edge, the second processing unit being disposed at a second position that is different from the first position in a vertical direction; and a moving unit configured to move the clamp from the first position to the second position or vice versa so that the clamp moves on a loop passing through the first position and the second position.
According to another embodiment, there is provided an image forming apparatus that includes the sheet processing device according to the above embodiment.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. According to an embodiment of the present invention, a plurality of processing units are set at vertically different positions. A clamp that clamps a portion of a sheet-like recording medium (hereinafter, simply referred to as “sheet”), such as paper, recording paper, transfer paper, or a transparency, is moved by a moving unit in a loop through the positions of the processing units by a simple mechanism, and predetermined processing is performed at the processing positions.
The image forming apparatus 100 is a tandem color image forming apparatus using an indirect transfer method. The image forming apparatus 100 includes, at or near its center (see
The image forming unit 110 includes photosensitive drums for the colors, or Y, M, C and K, in the respective image forming stations 111. There are provided an electrostatic charging unit, a developing unit, a primary transfer unit, a cleaning unit, and a neutralizing unit around each of the photosensitive drums. The image forming unit 110 also includes an intermediate transfer belt 112, onto which images formed on the photosensitive drums are to be intermediately transferred by the primary transfer unit, and the optical writing unit that writes each color image on the surface of each drum. The optical writing unit is disposed below the image forming stations 111. The intermediate transfer belt 112 is disposed above the image forming stations 111.
The intermediate transfer belt 112 is rotatably supported by a plurality of support rollers. A support roller 114, which is one of the support rollers, faces a secondary transfer roller 115 via the intermediate transfer belt 112 in the secondary transfer unit 140 so that secondary transfer of an image from the intermediate transfer belt 112 onto a sheet can be performed. Meanwhile, an image forming process performed by a tandem color image forming apparatus using an indirect transfer method is known and does not have direct relation with the scope of the present invention; accordingly, detailed description is omitted.
The sheet feeding unit 120 includes a sheet feed tray 121, a pickup roller 122, and sheet-feed conveying rollers 123. The sheet feeding unit 120 picks up a sheet from the sheet feed tray 121 and delivers the sheet upward along the vertical conveying path 130. The delivered sheet, onto which an image is transferred in the secondary transfer unit 140, is delivered to the fixing unit 150.
The fixing unit 150 includes a fixing roller and a pressing roller. During a course where the sheet passes through a nip between the fixing roller and the pressing roller, heat and pressure are applied to the sheet, causing toner to be fixed onto the sheet. The eject conveying path 160 and the duplex-printing conveying path 170, into which bifurcation is made at a bifurcating claw 161, are disposed downstream of the fixing unit 150. One of the conveying paths is selected depending on whether a sheet is to be conveyed to the sheet finisher 200 or to the duplex-printing conveying path 170. Meanwhile, bifurcation conveying rollers 162 are disposed immediately upstream of the bifurcating claw 161 with respect to a sheet conveying direction to apply a conveying force to the sheet.
The sheet finisher 200 arranged inside the image forming apparatus 100 performs predetermined processing on an image-formed sheet conveyed from the image forming apparatus 100, and places the sheet on an eject tray 210 arranged most downstream. The sheet finisher 200 will be described in detail later.
The image scanning apparatus 300 is of a known type that scans a document placed on an exposure glass with light to read an image on a document surface. The configuration and function of the image scanning apparatus 300 are known and do not have direct relation with the scope of the present invention; accordingly, detailed description is omitted.
The image forming apparatus 100 configured as roughly described above generates image data for use in writing from document data obtained by the image scanning apparatus 300 by scanning or from print data transferred from an external PC or the like. The optical writing unit performs optical writing on the photosensitive drums based on the image data. Images formed by the image forming stations on a per-color basis are sequentially transferred onto the intermediate transfer belt 112. A color image is formed on the intermediate transfer belt 112 by superimposing the four color images thereon.
Meanwhile, a sheet is fed from the sheet feed tray 121 according to the image forming operation. The sheet is temporarily stopped at a position of registration rollers (not shown) immediately upstream of the intermediate transfer unit 140 and, at timing synchronized to a leading end of the image on the intermediate transfer belt 112, delivered to the intermediate transfer unit 140 where secondary transfer of the image onto the sheet is performed. The sheet is then delivered into the fixing unit 150.
After the image is fixed in the fixing unit 150, when the image is formed for one-side printing or as a second-side image of duplex printing, the bifurcating claw 161 is operated for path switching so that the sheet is conveyed to the eject path 160. On the other hand, the sheet is conveyed to the duplex-printing conveying path 170 when the image is formed as a first-side image of duplex printing. The sheet conveyed to the duplex-printing conveying path 170 is turned upside down, and thereafter eventually delivered into the intermediate transfer unit 140 where an image is formed on a second side of the sheet. Thereafter, the sheet is conveyed to the eject path 160. The sheet delivered to the eject path 160 is conveyed to the sheet finisher 200. The sheet having undergone predetermined sheet processing or no processing in the sheet finisher 200 is ejected onto the eject tray 210.
Referring to
Specifically, at a sheet receiving section of the sheet finisher 200, there are provided the pair of inlet rollers 201 that receives a sheet P from the eject path 160 of the image forming apparatus 100, the eject conveying path 202 along which the received sheet P is conveyed to the punching unit, and the pair of conveying rollers 203. An inlet motor rotates the pair of inlet rollers 201 and the pair of conveying rollers 203, thereby conveying the sheet P along the eject conveying path 202 (in a direction indicated by arrow B1).
An inlet sensor (not shown) that detects a leading end and a trailing end of the sheet P is disposed on the eject conveying path 202. Based on (i) time when the inlet sensor detects the leading end and the trailing end, and (ii) numbers of steps taken by the inlet motor which is a stepping motor, timing for performing various sheet processing is determined. The inlet sensor is disposed near the inlet rollers 201 on the upstream side or the downstream side, for example.
In the image forming apparatus 100 according to the present embodiment, the sheet finisher 200 is arranged as illustrated in
After the punching unit 270 has punched the hole, the first clamp 401a moves along a guide 402 as illustrated in (c) of
In a mode that does not include hole punching, the punching operation to be performed by the punching unit 270 illustrated in (b) of
In the shift mode, the sheets P are not stapled but sorted into sets, each made up of predetermined number of sheets, that are alternately ejected on the eject tray 210 in a laterally staggered arrangement in the front view of the image forming apparatus (
After the sheet P has fallen onto the staple stage 250S, the clamp 401 brings the far-side edge Pb into contact with the trailing-end reference fences 207, thereby aligning the sheet P in the sheet conveying direction. The stapling jogger fences 208 align the sheet P in the direction perpendicular to the conveying direction.
An eject guide plate 212 and the eject rollers 209 are disposed most downstream of the staple tray 206. The sheet P conveyed in the direction indicated by arrow B1 to a far-side position in
When the sheets P are to be sorted into sets each made up of predetermined number of sheets, an aligning position (the position of the stapling jogger fences 208) for alignment in the direction perpendicular to the sheet conveying direction is shifted a preset distance. The sheet P is ejected from this position onto the eject tray 210. When sheets are loaded onto the eject tray 210 in this manner, positions where the sheets are ejected on the eject tray 210 are alternately shifted every predetermined number of sheets. Sheet sorting is thus achieved.
A sheet hold-down member 220 for holding down the sheets P loaded on the eject tray 210 is disposed at a portion where the eject tray 210 is mounted on a body of the sheet processing device 200. The sheet hold-down member 220 performs sheet hold-down releasing and sheet hold-down retention when a solenoid 221 is switched on and off. Specifically, in synchronization with conveyance of the sheet P, the solenoid 221 is switched on to cause the sheet hold-down member 220 to release hold-down retention; when the sheet P is conveyed past the eject rollers 209, the solenoid 221 is switched off to hold down the sheet P. Even when the solenoid 221 is switched off just when the sheet P is conveyed past the eject rollers 209, the solenoid 221 and the sheet hold-down member 220 are actuated after a certain time lag. This time lag allows the sheet P to be conveyed past the eject rollers 209 and fall onto the eject tray 210, and thereafter be slipped down by the pull of gravity in a direction opposite to the conveying direction. After abutting on an end fence 225, the sheet P is held down by the sheet hold-down member 220 on a movable tray member 222b. Alternatively, a configuration in which a delay time is set in advance, and when triggered by passage of the sheet P over the eject rollers 209, the sheet hold-down member 220 holds down the sheet P after the delay time can be employed.
The eject tray 210 includes a fixed tray member 222a on a downstream side with respect to the conveying direction and the movable tray member 222b on an upstream side. A tray DC motor 223a and a cam-link mechanism 223b move the movable tray member 222b up and down. The movable tray member 222b is pivotably supported at its pivot end, or an upstream end portion of the movable tray member 222b, by the fixed tray member 222a via a support shaft 223c. A moving end of the cam-link mechanism 221b is coupled to this movable tray 208b. With this configuration, when the tray DC motor 223a runs, the movable tray member 222b pivots about the support shaft 223c according to rotation of the tray DC motor 223a.
When the number of sheets ejected onto the movable tray member 222b reaches a certain value, the tray DC motor 223a rotates according to a command fed from a controller, which will be described later, thereby lowering a free end of the movable tray member 222b. A tray-sheet-level sensor (not shown) is disposed on the sheet hold-down member 220. The eject tray 210 loaded with the sheets P is maintained at a constant level as follows. When, in a state where the sheets P are held down by the sheet hold-down member 220, the tray-sheet-level sensor outputs a signal indicating OFF, the eject tray 210 is elevated until the sheet-level sensor outputs a signal indicating ON. When the sheet-level sensor outputs a signal indicating ON, the eject tray 210 is lowered until the sheet-level sensor outputs a signal indicating OFF and then elevated until a signal indicating ON is output.
The distance between a nip between the eject rollers 209 and a sheet loading portion of the movable tray member 222b is maintained at a constant distance as described above by moving up and down the free end of the movable tray member 222b according to a sheet loading state of the eject tray 210 so that a constant contact angle is kept between a sheet ejected by the eject rollers 209 and the movable tray member 222b. This allows maintaining consistent alignment quality of sheets loaded on the eject tray 210 and also loading a large number of sheets on the eject tray 210.
By repeating the operations described above, the sheets P are loaded on the eject tray 210 as being sorted.
In the staple mode, the sheets P are ejected as stapled sheet bundles each of which is made up of predetermined number of sheets and stapled by a stapler.
In the staple mode, the clamp 401 pushes the far-side edge Pb out of the punching unit 270. As the clamp unit 400 vertically moves, the clamp 401 moves until the sheet trailing ends P2 abut on the trailing-end reference fences 207. Sheet alignment in the sheet conveying direction is thus performed. This sheet alignment is performed with reference to the trailing-end reference fences 207 by bringing the sheets P into contact with the trailing-end reference fences 207. When the trailing ends of the sheets P have abutted on the trailing-end reference fences 207, the stapling jogger fences 208 arranged on the staple tray 206 align the sheets P in the direction perpendicular to the sheet conveying direction in a manner similar to that in the shift mode described above.
The stapling jogger fences 208 are disposed on the staple tray 206 as illustrated in
The staple tray 206 includes the trailing-end reference fences 207 mounted on a guide shaft (not shown) via a slider. The trailing-end reference fences 207 are configured to be movable in the same direction as the stapling jogger fences 208. A rack held by the slider is meshed with a gear disposed at approximately center of the staple tray 206. The trailing-end reference fences 207 move symmetrically with respect to the gear. The trailing-end reference fences 207 include guide portions at their ends. When a stapler unit 250 is moved, a base (not shown) of the stapler unit 250 contacts an inner side of the guide portion and pushes the guide portion. Accordingly, when the stapler unit 250 is moved, the trailing-end reference fences 207 are moved to follow the stapler unit 250.
Specifically, when the stapler unit 250 is moved toward an end of the staple tray 206, the trailing-end reference fences 207 move away from each other. When the stapler unit 250 is moved toward the center of the staple tray 206, the trailing-end reference fences 207 that are paired with each other approach to each other. This is because an elastic force is exerted to the trailing-end reference fences 207 by a spring (not shown) in a direction toward the center of the staple tray 206.
After the stapling, the eject guide plate 212 is lowered. The sheet bundle PBL is pinched and held between the eject rollers 209 and the driven roller 213 mounted on the eject guide plate 212, and ejected onto the eject tray 210. While the sheet bundle PBL is being ejected, the solenoid 221 is switched on to cause the sheet hold-down member 220 to release hold-down retention, and the eject tray 210 is lowered a predetermined amount. Subsequently, at a time when the trailing end of the sheet bundle PBL passes by a bundle eject sensor 224, the eject guide plate 212 is elevated to prepare for receiving a next sheet. At the same time, the solenoid 221 is switched off to perform sheet hold-down retention. At this time, the solenoid 221 and the sheet hold-down member 220 are actuated after a predetermined time lag. This time lag lets the sheet bundle PBL fall on the movable tray member 222b, the trailing end of the sheet bundle PBL abut on the end fence 225, and thereafter the sheet bundle PBL be held down by the sheet hold-down member 220 on the movable tray member 222b.
The guide 402 is fixed to a casing of the sheet finisher 400. The link 405 is mounted to be rotatable relative to the pivot point 404. As illustrated in
Illustrated in (b) of
When associated with
As described above, according to the present embodiment, the following effects are obtained.
1) it is possible to position the sheets P on a desired one of the punch stage 270S and the staple stage 250S by simply moving the link 405 in a loop so as to move the clamps 401 along the guide 402. Accordingly, because the sheet processing device can have a simple structure and does not require a large driving source to move the sheets P, device miniaturization can be achieved.
2) The sheet finisher 200 includes the punching unit 270 that punches holes at punching positions parallel to the sheet conveying direction B1 in which the sheets P are received from the image forming apparatus 100, and the stapler unit 250 that staples the sheets P at stapling positions parallel to the sheet conveying direction B1. The unit 270 and the unit 250 are arranged above and below with respect to each other. Delivery of the sheets P to the punch stage 270S and to the staple stage 250S is performed by clamping a portion of the sheets P with the first clamp 401a or the second clamp 401b and moving the sheets P along the guide 402. Accordingly, an increase of the sheet finisher 200 in size is prevented.
3) When the punching unit 270 punches holes, an edge face of the sheets P on a side where the holes are to be punched is brought into contact with the abutting member 502 of the clamp 401 to perform positioning. Accordingly, hole punching through the sheets P can be performed accurately.
4) When the punching unit 270 punches holes, the edge face of the sheets P on the side where the holes are to be punched is brought into contact with the abutting member 502 of the clamp 401 to perform positioning. Thereafter, the sheets P are clamped by the clamping member and then punched. Accordingly, the holes can be punched accurately because the sheets P do not go out of order during punching.
5) After the holes are punched by the punching unit 270, the sheets P are moved from the punch stage 270S to the staple stage 250S while being kept to be clamped by the clamp 401. Accordingly, even when the sheets P are moved up and down, the sheets P are moved onto the staple tray 206 orderly without going out of order.
6) The clamp 401 provides double functions, which are a sheet-edge-face aligning function for the punching unit 270 and a sheet-edge-face aligning function for the stapler unit 250. Accordingly, it is possible to perform punching and stapling on the sheets P accurately with an inexpensive structure.
7) The clamp unit 400 includes the first and second clamps 401a and 401b that are supported by the link 405. Accordingly, it is possible to perform punching and stapling while maintaining high productivity.
8) A moving path of the clamps 401 are looped along the guide 402. Accordingly, it is possible to perform punching and stapling while maintaining high productivity.
According to the embodiments, a sheet processing device is capable of moving sheets with a simple structure without using a large driving source. Accordingly, device miniaturization can be achieved.
Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-055961 | Mar 2012 | JP | national |
