Sheet processing apparatus and image forming system

A sheet processing apparatus includes a winding unit configured to wind a continuous sheet, a binding unit configured to bind the continuous sheet that is wound and stacked by the winding unit, and a first cutting unit configured to cut the continuous sheet that is bound by the binding unit in a state that the continuous sheet is wound by the winding unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to sheet processing apparatus and image forming system.

2. Description of the Related Art

Conventionally, there is an image forming system that includes an image forming apparatus such as a copying machine or a laser beam printer, and a sheet processing apparatus. Such a sheet processing apparatus takes in a sheet that is discharged after the image forming apparatus forms an image on the sheet and performs a bookbinding process. For example, sheets are folded in the middle or bound approximately at the center of the sheet and folded in two in a bookbinding process.

A conventional image forming apparatus can improve a throughput by shortening the distance between the sheets. For example, there is an image forming apparatus which continuously forms images at predetermined intervals on a continuous sheet in which there is no interval between the sheets that are rolled out from a sheet roll.

Moreover, there is a sheet processing apparatus which performs a process after winding a continuous sheet on which images are formed into a roll (refer to U.S. Pat. No. 5,138,821). Further, there is a sheet processing apparatus that performs a process after stacking the sheets on which images are formed into a z-shaped pattern (refer to U.S. Pat. No. 5,065,992).

FIG. 12illustrates an example of a conventional sheet processing apparatus which inserts a continuous sheet that is wound into a roll after images are continuously formed on the sheet into envelopes.

Referring toFIG. 12, an envelope roll34rolls up open envelopes58, and three sheet rolls28roll up continuous sheets on which images are continuously formed. A cutting unit40cuts the continuous sheet. A folding unit50folds the sheet cut by the cutting unit50, an inserting unit52inserts sheets folded by the folding unit into the envelopes58, and a central processing unit (CPU)54controls operations of such a sheet processing apparatus.

In a case where the sheet processing apparatus inserts sheets on which images are formed into the open envelopes58, continuous sheets are each sent out from the three sheet rolls28and cut by the cutting unit40. The folding unit50folds the cut sheets, and the inserting unit52inserts the folded sheets into the envelopes58.

The above-described conventional sheet processing apparatus can also cut a continuous sheet that is wrapped around a sheet roll and bind the cut sheets. However, it takes time to cut the sheets one by one from a continuous sheet and stack the sheets again to bind the sheets. Moreover, such a sheet processing apparatus needs a stapling unit, a double folding unit, and a cutting unit which cuts edges of a double folded sheet bundle instead of the inserting unit52.

A sheet processing apparatus which includes a stapling unit, a double folding unit, and a cutting unit as described above can perform a binding process. However, since a double folding process, a stapling process, and a cutting process are separate processes, the binding process takes a long time, and productivity decreases. Further, an amount of cutting wastage and consumption of the sheet roll increase if a cutting amount of edges of a double folded sheet bundle increases.

SUMMARY OF THE INVENTION

The present invention is directed to a sheet processing apparatus and an image forming apparatus that can improve productivity and decrease an amount of cutting.

According to an aspect of the present invention, a sheet processing apparatus includes a winding unit configured to wind a continuous sheet, a binding unit configured to bind the continuous sheet that is wound and stacked by the winding unit, and a cutting unit configured to cut the continuous sheet that is bound by the binding unit in a state that the continuous sheet is wound by the winding unit.

According to an exemplary embodiment of the present invention, productivity can be improved by cutting a continuous sheet that is wound by a winding unit and stacked.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1illustrates an example configuration of an image forming system including an image forming apparatus and a sheet processing apparatus according to an exemplary embodiment of the present invention. Referring toFIG. 1, an image forming apparatus1000includes an image forming apparatus main body102, a scanner104disposed on a top surface of the image forming apparatus main body102, and a bookbinding apparatus100that is a sheet processing apparatus. Further, the image forming apparatus1000includes a roll sheet feeding apparatus200that supplies a continuous sheet to the image forming apparatus main body102.

The scanner104reads an original image (not illustrated) which is placed on top of a platen glass103, or an original D which is conveyed onto the platen glass103by an automatic document feeder101. The image forming apparatus main body102includes an image forming portion102A that includes for example a photosensitive drum105, and forms an image according to the original image read by the scanner104.

Sheet rolls202,203are image formed sheets on one surface that are wrapped around roll core members201and are positioned one above the other in the roll sheet feeding apparatus200. The roll core member201of the upper sheet roll202rotates to feed a continuous sheet to the image forming apparatus main body102. When the upper sheet roll202runs out, a continuous sheet is fed to the image forming apparatus main body102from the lower sheet roll203.

An image forming operation of the image forming apparatus main body102will be described below. When the image forming apparatus main body102starts an image forming operation, the photosensitive drum105whose outer surface is charged rotates in the direction of the arrow. The scanner104then irradiates the original D placed on top of the platen glass103. Light reflected from the original D is radiated on the photosensitive drum105, and an electrostatic latent image is formed on the photosensitive drum105. The electrostatic latent image is developed by a developer106and visualized as a toner image.

In parallel with the above-described toner image forming operation, the roll sheet feeding apparatus200feeds a continuous sheet at predetermined timing to the image forming apparatus main body102. The continuous sheet is conveyed to a transfer unit107so as to match a leading edge of the toner image formed on the outer surface of the photosensitive drum105. As a result, the toner image formed on the outer surface of the photosensitive drum105is transferred onto an opposite surface of the image formed surface of the continuous sheet that is conveyed to the transfer unit107. In the present exemplary embodiment, an image formed continuous sheet on one surface is conveyed to the transfer unit107, and the toner image is formed on the opposite surface of the image formed surface. However, two facing image forming portions can be provided so that images formed both surfaces of the continuous sheet. By either both of the methods, a booklet can be produced in order of page.

A conveying unit108conveys the continuous sheet on which the toner image is transferred to a fixing unit109, and the fixing unit109fixes the toner image on the continuous sheet. The image forming apparatus main body102repeats the image forming operation to continuously form images at an interval of a predetermined length on the upper surface of the continuous sheet. The continuous sheet on which toner images are continuously formed at the interval of the predetermined length is discharged onto the bookbinding apparatus100. After a length of the continuous sheet that equals the number of sheets to be bound is conveyed to the book binding apparatus100, a cutter117cuts a rear end of the continuous sheet.

The bookbinding apparatus100which receives from the image forming apparatus main body102the continuous sheet on which images are continuously formed at the interval of the predetermined length includes a scoring device110, the above-described cutter117, and a drum112. Further, the bookbinding apparatus100includes a stapler118, a sheet bundle cutting device119, a stacking portion124, a folding portion129, and a trimming device130. In the present exemplary embodiment, the bookbinding apparatus100includes the cutter117and cuts the continuous sheet on which images have been formed into a length that equals the number of sheets to be bound. However, the cutter117can be included in the image forming apparatus main body102, and the continuous sheet can be cut into a length that equals the number of sheets of a booklet to be produced before images are formed on the sheet.

The scoring device110applies pressure on the continuous sheet and forms a grooved crease on the continuous sheet P as a folding portion as illustrated inFIG. 2. The scoring unit110includes a pushing member110awhich moves back and forth in a direction of thickness of the continuous sheet P, and a receiving member110b. The above-described groove portion is formed between images on the continuous sheet P, so that a continuous sheet bundle can be smoothly and precisely folded, as will be described below.

The drum112winds the continuous sheet on which groove portions are formed by the scoring device110, to wrap the sheet around the periphery of the drum112for a predetermined number. The drum112includes a gripper112athat grips a leading end of the sheet P as illustrated inFIGS. 7A and 7B. The drum112winds the continuous sheet by rotating while the gripper112agrips the leading end of the continuous sheet.

An outer surface member112bwhich configures the periphery of the drum112(i.e., a winding unit), is movable in a radial direction of the drum112. Therefore, the outer diameter of the drum112can be adjusted according to the size of a bookbinding sheet which is to be output by the bookbinding apparatus100. For example, if the bookbinding apparatus100is to form a large-size output, the outer surface member112bis moved away from the center of the drum112, so that the outer diameter of the drum112matches the size of the sheet.

The above-described continuous sheet tends to curl. However, the continuous sheet can be smoothly wound using the cylindrical drum112. As a result, a sheet correction mechanism and energy to be applied to correct the sheet are not necessary, so that energy saving and noise-reduction can be realized.

The stapler118staples the continuous sheet stacked on the drum112at two opposed positions, i.e., positions that are 180 degrees shifted with each other. When the stapler118is not operating, the stapler118moves to a retracted position lateral to the drum112so that the stapler118does not prevent the drum112from winding the continuous sheet.

The sheet bundle cutting device119cuts the continuous sheet that is wrapped around the drum112in a bundle after the stapler118staples the continuous sheet. As illustrated inFIG. 3, the sheet bundle cutting device119, namely a first cutting device includes a rotatable cutter121and a holder120that pivotally supports the cutter121via a shaft122.

The holder120is movable in the direction of width of the continuous sheet P, i.e., in a direction perpendicular to the sheet conveying direction of the continuous sheet P that is indicated by the arrow A along the shaft122. Further, wires123which are suspended between two pulleys (not illustrated) are fixed onto the holder120. As a result, when the pulley driving motor (not illustrated) is driven, the sheet bundle cutting device119is moved in the direction indicated by the arrow A along the shaft122.

The sheet bundle cutting device119is generally in a standby position lateral to the drum112, as illustrated inFIG. 4A. When cutting a sheet bundle, the sheet bundle cutting device119moves in the direction of the width of the drum112according to the motion of the pulley driving motor. In such a case, the sheet bundle cutting device119causes the cutter121to rotate and move toward the drum112as indicated by the arrow B illustrated inFIG. 4BandFIG. 3. As a result, the sheet bundle cutting device119can cut a bundle of the continuous sheet P which is wrapped around the drum112at two opposed positions that are 90 degrees shifted from the positions stapled by the stapler118.

Consequently, the continuous sheet that is stapled by the stapler118at positions that are 180 degrees shifted from each other is separated into two sheet bundles. Further, the portion of the continuous sheet that is positioned at the lower side of the drum112drops as a sheet bundle that is stapled at the center. As described above, the continuous sheet which is stapled by the stapler118can be cut at intervals between the images that are continuously formed at a minimal distance. Further, alignment of the continuous sheet is kept even if the continuous sheet is dropped after cutting.

In the present exemplary embodiment, the continuous sheet P wrapped around the drum112is stapled at two positions and cut at two positions. However, the position at which the continuous sheet is stapled or cut is not limited to the above-described positions. For example, if a long sheet bundle is desirable, the continuous sheet can be stapled and cut at one position. Further, the continuous sheet can be stapled and cut at three or more positions so that three or more sheet bundles can be formed at once. Further, an end binding sheet bundle can be formed by binding an edge of the sheet bundle and omitting the folding process which is described below.

The stacking portion124is disposed below the drum112as illustrated inFIG. 1. The stacking portion124stacks a sheet bundle dropped from the drum112by cutting the continuous sheet with the sheet bundle cutting device119.

The stacking portion124is set on an upper surface of a dolly125that is equipped with wheels126as illustrated inFIGS. 7A and 7B. After the sheet bundle is stacked onto the stacking portion124, the dolly125is moved, so that the sheet bundle can be conveyed to the folding portion129. There is a rectangle hole125aat the center of the stacking portion124.

The sheet bundle conveyed by the dolly125is folded in two by the folding portion129. The folding portion129includes a pushing rod129aused to push the center of the sheet bundle into the rectangle hole125ain the center of the stacking portion124as illustrated inFIGS. 7A and 7B. By pushing the pushing member129ainto the rectangle hole125a, the sheet bundle which is stacked on the stacking portion124with the binding position at the center, is bent downwards and folded.

The trimming device130is set downstream from the folding portion129. The trimming device130, namely a trimming unit trims a rear end, namely an edge on the opposite side of the stapled position of the sheet bundle that is folded in two by the folding portion129. Referring toFIG. 1, a sheet detection sensor111detects the leading end of the sheet.

FIG. 5is an example control block diagram of the above-described bookbinding apparatus100. Referring toFIG. 5, a controller300controls a bookbinding process of the bookbinding apparatus100. The controller300is included in the bookbinding apparatus100or the image forming apparatus main body102.

The controller300controls a scoring motor113that moves back and forth the pushing member110aof the scoring apparatus110, and a drum driving motor115that rotates the drum112. Further, the controller300controls a gripper solenoid114that causes the gripper112aset on the drum112to operate, and a drum periphery driving motor116that moves the outer surface member112bwhich configures the periphery of the drum112in the radial direction of the drum112.

Further, the controller300controls a dolly driving motor127that drives the wheels126for moving the dolly125, and a pushing rod driving motor128that drives the pushing rod129aof the folding portion129. Further, the controller300controls a stapler driving motor118bthat moves the stapler118between a retracting position and an operating position, and a stapler driving solenoid118athat drives the stapler118.

A bookbinding control process of the bookbinding apparatus100will be described below with reference to the flowchart illustrated inFIG. 6.

A continuous sheet P on which continuous images are formed by the image forming apparatus main body102enters the bookbinding apparatus100as illustrated inFIG. 7A. In step S101, the controller300activates the scoring device110. Consequently, the scoring motor113is driven (seeFIG. 5), so that the pushing member110ain the scoring device110moves toward the continuous sheet P to apply pressure on the continuous sheet P. As a result, a groove portion is formed on the continuous sheet P as a folding portion, as illustrated inFIG. 2. The groove portion is successively formed between the continuous images on the continuous sheet P.

In step S102, if the sheet detection sensor111detects a leading end of the continuous sheet P and is activated (YES in step S102), the controller300stops conveying the continuous sheet when the continuous sheet P runs into the gripper112ainside the drum112according to a detection signal from the detection sensor111. In step S103, the controller300applies voltage on the gripper solenoid114and activates the gripper112a. As a result, the continuous sheet P is gripped by the gripper112awhich moves in the direction of the arrow illustrated inFIG. 7A.

In step S104, the controller300drives the drum driving motor115(seeFIG. 5), and rotates the drum112while the gripper112agrips the leading end of the continuous sheet P. As a result, as illustrated inFIG. 7B, the continuous sheet P is wrapped around the drum112a predetermined number of times, i.e., a length that equals the number of sheets of a booklet to be produced. The outer diameter of the drum112is adjusted to match the size of the output result (i.e., bookbinding sheets).

In step S105, if the continuous sheet P is conveyed for a length that can be wrapped around the drum112a predetermined number of times, i.e., a length that equals the number of sheets to be bound to the bookbinding apparatus100(YES in step S105), the process proceeds to step S106. In step S106, the controller300activates the cutter117, and the cutter117cuts the rear end of the continuous sheet P. As a result, the length of the continuous sheet P that equals the number of sheets to be bound is wrapped around the drum112, and conveyance of the continuous sheet P is temporarily stopped.

In step S107, the controller300activates the stapler118. As a result, the stapler driving motor118b(seeFIG. 5) is driven, and the stapler118is moved from a retracting position to a predetermined operating position as illustrated inFIG. 8A. The stapler driving solenoid118a(seeFIG. 5) is activated at this position and staples the bundled continuous sheet P at two positions in the direction of the width of the continuous sheet P.

Further, the controller300rotates the drum112by 180 degrees, and the stapler118again staples at two positions in the width direction. Instead of rotating the drum112, the stapler118can be rotated 180 degrees around the drum112and staple the continuous sheet P.

After the continuous sheet P is stapled at positions shifted 180 degrees by the stapler118, in step S108, the controller300activates the sheet bundle cutting device119illustrated inFIG. 8B. The sheet bundle cutting device119cuts the continuous sheet P at two opposing positions that are located midway between the two stapled positions, i.e., positions that are 90 degrees shifted from the stapled positions. As a result, the continuous sheet P wrapped around the drum112is separated into two sheet bundles. Further, the sheet bundle that is positioned at the lower portion of the drum112and stapled at the center is dropped.

In step S109, the controller300starts conveying a sheet bundle P1, illustrated inFIG. 9A, which is the sheet bundle dropped from the drum112onto the stacking portion124on top of the dolly125.

The dolly driving motor127(seeFIG. 5) is driven to rotate the wheels126. The sheet bundle P1stacked on the stacking portion124is then conveyed to a position where the rectangle hole125ain the center of the stacking portion124approaches the pushing rod129aof the folding portion129. The sheet bundle P1formed by the sheet bundle cutting device119is stacked on the stacking portion124so that the stapling position of the sheet bundle P1is aligned with the rectangle hole125ain the center of the stacking portion124.

In step S110, the controller300activates the folding portion129. The pushing rod activating motor128is then activated, and the pushing rod129ais pushed into the rectangle hole125aof the stacking portion124. As a result, the sheet bundle P1stacked on the stacking portion124is bent downward and folded as illustrated inFIG. 1A.

The position of the sheet bundle P1which the pushing rod129acontacts is the stapling position as well as the position where the scoring device110has formed the groove portion. Therefore, the sheet bundle P1can be smoothly and correctly folded.

After the sheet bundle P1is folded, the dolly125returns to the position illustrated inFIGS. 8A and 8B, and the drum112rotates 180 degrees. Consequently, a sheet bundle P2which is remaining on the drum112is stacked onto the stacking portion124. A folding process similar to that performed on the sheet bundle P1is performed on the sheet bundle P2.

The sheet bundles P1and P2are conveyed on the dolly125through the conveyance path R illustrated inFIG. 10B, and the dolly125stops when the rear ends of the sheet bundles P1, P2enter the trimming device130. In step S111, the controller300then activates the trimming device130, and the trimming device130trims the rear ends of the sheet bundles P1and P2. In step S112, the trimmed sheet bundles P1and P2are discharged onto a shift tray131. The shift tray131descends in the direction indicated by an arrow C illustrated inFIG. 10Bevery time the sheet bundles P1and P2are discharged, so that the sheet bundles P1and P2are sequentially stacked.

FIG. 11Aillustrates the sheet bundle P1(P2) that is dropped onto the stacking portion124. In a case where the continuous sheet P wrapped around a cylindrical drum is cut perpendicularly to a tangent line to the periphery of the drum, the cut sheet bundle P1(P2) is shaped proximately like a trapezoid. This is caused by the difference between the inner and outer diameters of the sheet bundle that is wrapped around the cylindrical drum a predetermined number of times. Further, when the trimming device130trims the sheet bundles P1and P2to align the rear ends of the sheet bundles, the cutting direction of the trimming device130is perpendicular to the sheet surface, to improve the appearance of the sheet bundles.

If the sheet bundle P1(P2) with a trapezoidal shape is folded in the direction of the dotted arrow, the edge of the folded sheet bundle P1(P2) becomes sharp, as illustrated inFIG. 11B. In a case where the rear ends of the sheet bundles P1and P2are trimmed in such a state, the edges are trimmed at the position indicated by the dotted line illustrated inFIG. 11B.

On the other hand, in the present exemplary embodiment, the sheet bundle P1(P2) is folded in the direction of the solid arrow illustrated inFIG. 11A. That is, the sheet bundle P1(P2) is folded in a direction from the inner periphery to the outer periphery of the sheet bundle P1(P2) when the sheet bundle P1(P2) is wound by the drum.

The edge of the sheet bundle P1(P2) that is folded in the above-described direction does not become sharp. Instead, the edge becomes nearly flat as illustrated inFIG. 11C, so that there is hardly any portion to be trimmed.

As described above, an amount trimmed by the trimming device130which performs the final process of the sheet bundle can be small by folding the sheet bundle P1(P2) in the direction from the inner periphery to the outer periphery of the sheet bundle P1(P2) when the sheet bundle P1(P2) is wound on the drum. The trimming process by the trimming device130can be omitted in a case where a simple booklet such as a pamphlet is created. As a result, the amount of cutting wastage can be reduced, and the amount of continuous sheet to be used can be reduced.

As described above, according to the present exemplary embodiment, a continuous sheet is wrapped around a drum and then cut out as a bundle. As a result, the bookbinding process can be performed much faster and productivity is improved as compared to cutting one sheet at a time. Further, the sheet bundle is folded in the direction from the inner periphery to the outer periphery of the continuous sheet bundle wound by the drum, so that the amount of trimming can be reduced, or the trimming process can be omitted.

In the above-described exemplary embodiment, the image forming apparatus main body102is an analog apparatus which scans an original by an exposing device and forms an image on the photosensitive drum105. However, the present invention is not limited to such an analog apparatus. The present invention can be applied to a digital apparatus which irradiates the photosensitive drum105with a laser beam according to the read original image information to form the image on the photosensitive drum105.

This application claims priority from Japanese Patent Applications No. 2007-111304 filed Apr. 20, 2007 and No. 2008-095500 filed Apr. 1, 2008, which are hereby incorporated by reference herein in its entirety.