Patent Publication Number: US-9835998-B2

Title: Sheet processing apparatus

Description:
FIELD 
     Embodiments described herein relate generally to a technology of aligning sheets and a technology of picking up the sheets. 
     BACKGROUND 
     There is a sheet processing apparatus which can execute both a decoloring processing and an image forming processing. In the sheet processing apparatus, it is considered that a cassette is used as not only a sheet discharge cassette for stacking the discharged sheet subjected to the decoloring processing, but also a sheet feed cassette for feeding the sheet to be subjected to the image forming processing. 
     In this case, it is required to equip with a pickup mechanism in the sheet processing apparatus to pick up sheets from the cassette. Further, in order to ensure the accuracy when performing the image forming processing on the sheet, it is required to equip with an alignment mechanism to align the sheets to be discharged to the cassette. 
     Thus, when the cassette is used as both the sheet discharge cassette and the sheet feed cassette in the sheet processing apparatus, there is a problem that the sheet processing apparatus becomes large-sized because it is required to equip with the alignment mechanism in addition to the pickup mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an image forming apparatus; 
         FIG. 2  is a diagram illustrating a second cassette, a moving mechanism and a combined roller; 
         FIG. 3  is a diagram illustrating an alignment position; 
         FIG. 4  is a flowchart illustrating an alignment processing at the time of a decoloring processing; 
         FIG. 5  is a diagram illustrating a sheet feed processing; 
         FIG. 6  is a diagram illustrating the moving mechanism; 
         FIG. 7  is a flowchart illustrating the alignment processing at the time of the decoloring processing; 
         FIG. 8  is a diagram illustrating a combined roller located at the alignment position; 
         FIG. 9  is a diagram illustrating a sheet feed processing; 
         FIG. 10  is a diagram illustrating an alignment position; 
         FIG. 11  is a diagram illustrating a standby position; 
         FIG. 12  is a flowchart illustrating the alignment processing at the time of the decoloring processing; and 
         FIG. 13  is a diagram illustrating a sheet alignment method by the combined roller. 
     
    
    
     DETAILED DESCRIPTION 
     In accordance with an embodiment, a sheet processing apparatus comprises a decoloring section, a stacking section, an image forming section, a sheet feed roller and a combined roller. The decoloring section carries out a decoloring processing on a sheet. The sheet subjected to the decoloring processing is discharged to the stacking section. The image forming section carries out an image forming processing on the sheet fed from the stacking section. The sheet feed roller feeds a sheet stacked in the stacking section to a conveyance path through which the sheet is fed to the image forming section. The combined roller aligns the sheets to be discharged to the stacking section at a reference position in a conveyance direction in which the sheets are conveyed to the sheet feed roller, and feeds the sheets stacked in the stacking section to the sheet feed roller along the conveyance direction. 
     Hereinafter, embodiments are described with reference to the accompanying drawings. 
     (A First Embodiment) 
     (Whole Constitution) 
       FIG. 1  is a diagram illustrating an image forming apparatus  1  (sheet processing apparatus). 
     The image forming apparatus  1  can execute a decoloring processing for decoloring an image on a sheet to enable the sheet to be reusable and an image forming processing for forming an image on a sheet. 
     The image forming apparatus  1  comprises a processor  11 , a memory  12 , a display section  13  and an input section  14 . 
     The processor  11  reads programs in the memory  12  to carry out various processing of the image forming apparatus  1 . The display section  13  displays setting information and operation status of the image forming apparatus  1 , log information and notifications for a user. The input section  14 , which is equipped with buttons and keys, receives input operations by the user. 
     The image forming apparatus  1  comprises a first cassette  15 , a decoloring section  16 , conveyance rollers  17 , a sheet discharge roller  18 , a second cassette  19  (stacking section), a combined roller  20 , a sheet feed roller  21 , a separation roller  22 , a moving mechanism  23 , an image forming section  24 , a fixing device  25  and a sheet discharge stack  26 . 
     The first cassette  15  is located at the lower part of the image forming apparatus  1 . The first cassette  15  stacks sheets on which images are formed with decolorable color material. The decolorable color material includes a color generation compound, a developer and a decoloring agent. For example, the leuco dye which generates blue color is exemplified as the color generation compound. For example, the phenols is exemplified as the developer. A substance which is compatible with the color generation compound when being heated, and has no affinity with the developer is exemplified as the decoloring agent. The decolorable color material generates a color through an interaction between the color generation compound and the developer, and is decolored when the interaction between the color generation compound and the developer is eliminated if being heated to a temperature higher than the decoloring temperature. The decolorable color material may be decolorable toner or decolorable ink. In the present embodiment, it is assumed that the image on the sheet is formed with the decolorable toner. 
     The decoloring section  16  is arranged at the lower part of the image forming apparatus  1  and is adjacent to the first cassette  15 . The decoloring section  16  is equipped with a heat roller which is contacted with one side and the other side of the sheet. The decoloring section  16  heats one side and/or the other side of the sheet through the heat roller to decolor the images on the sheet. 
     Further, the “decoloring” in the present embodiment refers to making an image formed with a color (including not only chromatic color but also achromatic color such as white and black) different from the ground color of a sheet invisible or hardly visible. Herein, “make an image invisible” may refer to changing the color of the image formed in a color different from the ground color of sheet to be same as or similar to the ground color of sheet, in addition to making the image formed in a color different from the ground color of sheet colorless (transparent). 
     The conveyance roller  17  includes a pair of rollers facing to each other to convey sheets to the downstream side in the conveyance direction. Further, in the following description, there is a case in which only “downstream side” is recorded, and it means “the downstream side in the sheet conveyance direction” in this case. Further, in a case of recording “downstream”, it also means “the downstream in the sheet conveyance direction”. Similarly, it is also applicable to the cases in which “upstream” and “upstream side” are recorded. 
     The sheet discharge roller  18  is located at the upstream side of the second cassette  19  and at one end in the horizontal direction in  FIG. 1 . The sheet discharge roller  18  includes a pair of rollers facing to each other to discharge the sheet to the second cassette  19 . 
     For example, a light transmission type sheet sensor  181  ( FIG. 2 ) which detects that the sheet passes through the sheet discharge roller  18  is arranged at the upstream side of the sheet discharge roller  18 . The sheet sensor  181  may be arranged at the downstream side of the sheet discharge roller  18 . 
     The second cassette  19  is arranged above the first cassette  15 . The second cassette  19  stacks the sheets subjected to decoloring processing. By drawing first cassette  15  and the second cassette  19  from the image forming apparatus  1  in a direction perpendicular to paper in the  FIG. 1 , the user can put sheets into the first cassette  15  and the second cassette  19 , and can take out sheets from the first cassette  15  and the second cassette  19 . 
     A conveyance path  91  starts from the first cassette  15  to the second cassette  19 . On the conveyance path  91 , there are the decoloring section  16 , the conveyance roller and the sheet discharge roller  18 . In  FIG. 1 , the conveyance path  91  extends from the first cassette  15  to left side, turns upward and right sequentially, and finally to the second cassette  19 . 
     A conveyance path  92  is arranged to convey the sheet from the second cassette  19  to the image forming section  24 . In  FIG. 1 , the conveyance path  92  extends from the sheet feed roller  21  to the right side, turns upward and then extends upward. Along the conveyance path  92 , the sheet feed roller  21 , the separation roller  22 , the conveyance roller  17 , the image forming section  24  and the fixing device  25  are arranged. 
     The sheet feed roller  21  faces the separation roller  22 . The sheet feed roller  21  and the separation roller  22  feed the sheets inside the second cassette  19  one by one on the conveyance path  92 . 
     The separation roller  22  presses against the sheet feed roller  21 . A torque in a rotation direction (the anticlockwise direction in  FIG. 1 ) in which the sheet is conveyed in a returning direction reverse to the conveyance direction is transmitted to the separation roller  22 . In a case in which one sheet enters a space between the sheet feed roller  21  and the separation roller  22 , the separation roller  22  rotates along with the rotation of the sheet feed roller  21 . In a case in which two or more than two sheets enter the space between the sheet feed roller  21  and the separation roller  22 , the conveyance of the sheet at the lowermost is stopped by the separation roller  22 . Only the one sheet at the uppermost is sequentially conveyed to the downstream side in the sheet conveyance direction by the sheet feed roller  21 . 
     The conveyance roller  17  conveys the sheet conveyed to the conveyance path  92  by the sheet feed roller  21  to the image forming section  24 . 
     The image forming section  24  forms images with toner of four colors (Y, M, C and K) on photoconductive drums  241 Y,  241 M,  241 C and  241 K respectively for aforementioned four colors through a laser optical system. The image forming section  24  overlaps the images on the photoconductive drums  241 Y,  241 M,  241 C and  241 K on a transfer belt  242  to form one color image. The image forming section  24  transfers the color image on the transfer belt  242  to the sheet. 
     The image forming section  24  may be a mechanism which transfers the images from the photoconductive drums to the sheet directly without using the transfer belt  242 . The image forming section  24  may form an image on the sheet with the decolorable toner. The image forming section may form an image on the sheet with ink or decolorable ink through an inkjet head. The image forming section  24  may be capable of transferring only monochrome image to the sheet. 
     The fixing device  25  heats the sheet to fix the image that is on the sheet to the sheet. The sheet subjected to fixing processing by the fixing device  25  is discharged to the sheet discharge stack  26 . 
     (Alignment Operations and Pickup Operations of Sheets) 
       FIG. 2  is a diagram illustrating the second cassette  19 , the moving mechanism  23  and the combined roller  20 . 
     There is a plate-shaped sheet tray  191  in the second cassette  19 . The sheet tray  191  stacks sheets discharged to the second cassette  19 . The A4-sized sheets or letter-sized sheets are stored in a manner that the short-side direction is along the conveyance direction in the first cassette  15  and the second cassette  19 . 
     When the second cassette  19  is arranged inside the image forming apparatus  1 , the sheet tray  191  is maintained in a horizontal state by springs  192 . When the second cassette  19  is arranged inside the image forming apparatus  1 , the sheet tray  191  may be arranged in such a manner that the end at the upstream side (the side of the sheet discharge roller  18 ) is inclined downward towards the other end at the downstream side (the side of the sheet feed roller  21 ), or arranged in such a manner that the end at the upstream side (the side of the sheet discharge roller  18 ) is inclined upward towards the other end at the downstream side (the side of the sheet feed roller  21 ). 
     The moving mechanism  23  enables a link  232  to rotate around a rotary shaft  231  located at the upstream side (the side of the sheet feed roller  21 ). In this way, the moving mechanism  23  enables the combined roller  20  at the front end of the link  232  to ascend and descend between a home position in  FIG. 2  and an alignment position (sheet feed position) in  FIG. 3 . 
     The home position of the combined roller  20  is a position where the combined roller  20  is separated from and above the sheets stacked in the second cassette  19 . The alignment position is a position (a contactable position with sheet) where the combined roller  20  is abutted against the sheets stacked in the second cassette  19 . The alignment position is closer to the sheet feed roller  21  than the sheet discharge roller  18  in the sheet conveyance direction towards the sheet feed roller  21 . 
     A torque in a direction in which the combined roller  20  is rotated in the conveyance direction in which the sheet is send to the downstream side is transmitted to the combined roller  20 . For example, such a torque is transmitted from the sheet feed roller  21  to the combined roller  20  via a gear or belt. 
     Hereinafter, an alignment processing at the time of decoloring processing is described with reference to the flowchart in  FIG. 4 . 
     If receiving an instruction to carry out a decoloring processing, the processor  11  takes out a sheet from the first cassette  15 , and heats the sheet through the decoloring section  16  to decolor an image on the sheet. 
     As shown in  FIG. 2 , the processor  11  discharges the sheet subjected to the decoloring processing to the second cassette  19  with the sheet discharge roller  18 . 
     The processor  11  detects that the downstream end (front end) in the conveyance direction of the sheet reaches the alignment position directly under the combined roller  20  (YES in ACT  1 ). 
     Specifically, when the sheet discharge roller  18  is driven to rotate at a given amount (a given number of pulses) after the downstream end of sheet is detected by the sheet sensor  181 , or when the sheet discharge roller  18  is driven to rotate at a given amount after the upstream end of the sheet passes through the sheet sensor  181 , the processor  11  detects that the downstream end in the conveyance direction of the sheet reaches the alignment position directly under the combined roller  20 . 
     As shown in  FIG. 3 , the processor  11  enables the combined roller  20  at the home position to descend to the alignment position through the moving mechanism  23  in such a manner that the combined roller  20  presses against the sheets. (ACT  2 ) 
     The processor  11  enables the combined roller  20  to rotate to send the sheet to the downstream side until the downstream end of the sheet abuts against a wall portion  193  at the downstream end of the second cassette  19  (ACT  3 ). In this way, the sheet is aligned at the reference position where the downstream end of the sheet is contacted with the wall portion  193  in the conveyance direction. 
     It is assumed that when the combined roller  20  is contacted with the sheet, the upstream end of the sheet is clamped by the sheet discharge roller  18 , and it may also be not clamped. The processor  11  may enable the combined roller  20  to descend while rotating it to abut against the sheet, or may enable the combined roller  20  to rotate after the combined roller  20  abuts against the sheet. 
     The processor  11  enables the combined roller  20  to ascend through the moving mechanism  23  to locate at the home position (ACT  4 ). 
       FIG. 5  is a diagram illustrating a sheet feed processing. 
     If receiving an instruction to carry out an image forming processing, the processor  11  enables the combined roller  20  at the home position to descend to the alignment position (sheet feed position) through the moving mechanism  23 . 
     The processor  11  enables the combined roller  20  to rotate to feed a sheet in the second cassette  19  to the sheet feed roller  21 . This sheet, which is subjected to the decoloring processing, is a reusable sheet. The processor  11  may enable the combined roller  20  to descend while rotating it to abut against the sheet, or may enable the combined roller  20  to rotate after the combined roller  20  abutted against the sheet. 
     The processor  11  enables the sheet feed roller  21  to rotate to feed the sheet to the conveyance path  92 . 
     After an image is formed by the image forming section  24  on the sheet, the processor  11  enables the fixing device  25  to fix the image on the sheet. 
     The processor  11  discharges the sheet to the sheet discharge stack  26 . 
     In the present embodiment, a pickup mechanism (including the components  11 ,  12  and  20 ˜ 23 ) which carries out the sheet feed processing at the time of the image forming processing is also used as an alignment mechanism which carries out the sheet alignment processing after the decoloring processing is carried out. Thus, it is possible not to equip with an alignment mechanism dedicated for the alignment processing, which can miniaturize the apparatus in the present embodiment. 
     (A Second Embodiment) 
       FIG. 6  is a diagram illustrating a moving mechanism  23 A. 
     The moving mechanism  23 A moves the combined roller  20  along the conveyance direction, and positions the combined roller  20  at the alignment position when the sheets are aligned. When the sheet is fed by the sheet feed roller  21 , the moving mechanism  23 A positions the combined roller  20  at a paper feed position different from the alignment position. 
     The moving mechanism  23 A includes the rotary shaft  231  and a conveyance direction moving mechanism  233  which moves the link  232  in the conveyance direction. 
     The conveyance direction moving mechanism  233  is provided with a nut  234 , a screw shaft  235 , holding sections  236  and a motor  237 . The nut  234  supports and rotates the rotary shaft  231 . The screw shaft  235  is inserted into the nut  234 . The holding sections  236  hold the two ends in the longitudinal direction of the screw shaft  235  in a rotatable manner. The motor  237  is driven to rotate the screw shaft  235  to move the nut  234  in the conveyance direction. 
     As indicated by one-dotted lines in  FIG. 6 , the home position of the combined roller  20  is such a position from which the combined roller  20  can be positioned at the sheet feed position by only being lowered. That is, the home position of the combined roller  20  corresponds to the sheet feed position and is located above the sheet feed position. 
     The alignment position of the combined roller  20  refers to such a position where the upstream side of the sheet of which the downstream end of sheet is abutted against the wall portion  193  of the second cassette  19  is contacted with the combined roller  20 . 
     Before a decoloring processing is started, the processor  11  acquires a sheet size in advance. By setting the sheet size in advance, or by receiving the setting on the sheet size through the input section  14 , the processor  11  acquires the sheet size. 
     The processor  11  determines the alignment position based on the sheet size. In the present embodiment, the processor  11  determines the alignment position on the condition that the upstream side of sheet is clamped by the sheet discharge roller  18  when the combined roller  20  is in contact with the sheet. Thus, the processor  11  determines the alignment position to be at the upstream side when the sheet size gets small. When a curl is generated at the upstream end of sheet, the upstream end of the sheet may jam in the sheet discharge roller  18 . In the case in which the upstream side of sheet is clamped by the sheet discharge roller  18  when the combined roller  20  is in contact with the sheet, the combined roller  20  can assist in conveying the sheet to the downstream side. Consequently, it is preferred that the upstream side of the sheet is clamped by the sheet discharge roller  18  when the combined roller  20  is in contact with the sheet. 
     Hereinafter, an alignment processing at the time of the decoloring processing is described with reference to the flowchart in  FIG. 7 . 
     If receiving an instruction to carry out a decoloring processing, the processor  11  picks up a sheet from the first cassette  15  to perform a decoloring processing on the sheet. The processor  11  determines an alignment position and a standby position corresponding to the alignment position based on a sheet size. The standby position corresponding to the alignment position refers to a position from which the combined roller  20  can be positioned at the alignment position by only being lowered. The processor  11  moves the combined roller  20  from the home position in  FIG. 6  to the standby position along the conveyance direction (ACT  11 ). 
     The processor  11  discharges the sheet to the second cassette  19  through the sheet discharge roller  18 , and detects that the downstream end of the sheet reaches the alignment position directly under the combined roller  20  (YES in ACT  12 ). 
     As shown in  FIG. 8 , the processor  11  enables the combined roller  20  at the standby position to descend with the moving mechanism  23  to the alignment position in such a manner that the combined roller  20  presses against the upstream side of sheet (ACT  13 ). It is assumed that when the combined roller  20  is in contact with the sheet, the upstream side of sheet is clamped by the sheet discharge roller  18 , and it may also not be clamped by the sheet discharge roller  18 . Further, the conveyance direction moving mechanism  233  is not shown in  FIG. 8 . 
     The processor  11  rotates the combined roller  20  to feed the sheet to the downstream side to make the downstream end of sheet abut against the wall portion  193  of the second cassette  19  (ACT  14 ). At this time, after the downstream side of sheet bends upward, the sheet stretches to the upstream side and is aligned in a state in which the downstream end of the sheet is abutted against the wall portion  193  of the second cassette  19 . 
     Further, at this time, the processor  11  changes the feeding amount of sheet towards the conveyance direction by the combined roller  20  in response to the sheet size to align the sheet properly. The smaller (smaller than the predetermined size) the sheet size is, the longer the distance from the sheet when the combined roller  20  is being contacted with the sheet to the wall portion  193  is; the larger (larger than the predetermined size) the sheet size is, the shorter the distance from the sheet when the combined roller  20  is being contacted with the sheet to the wall portion  193  is. Thus, the processor  11  sets a larger sheet feeding amount if the sheet size is smaller than the predetermined size, and sets a smaller sheet feeding amount if the sheet size is larger than the predetermined size. 
     After the combined roller  20  is lifted up with the moving mechanism  23 , the processor  11  positions the combined roller  20  at the home position (ACT  15 ). 
     In the present embodiment, since the alignment position is set to be at an appropriate position according to a sheet size, the sheet can be aligned properly and the sheet feed failure can also be suppressed. 
       FIG. 9  is a diagram illustrating a sheet feed processing. 
     If receiving an instruction to carry out an image forming processing, the processor  11  enables the moving mechanism  23  to lift the combined roller  20  at the home position down to the sheet feed position. 
     The processor  11  rotates the combined roller  20  to feed a sheet in the second cassette  19  to the sheet feed roller  21 . The processor  11  feeds the sheet to the conveyance path  92  with the sheet feed roller  21 , and forms an image on the sheet with the image forming section  24 . 
     As indicated by the one-dotted lines in  FIG. 6 , the home position of the combined roller  20  corresponds to the sheet feed position and is located above the sheet feed position in the present embodiment. Thus, the combined roller  20  can be positioned at the sheet feed position only by lowering it down from the home position in the present embodiment, and thus it is possible to shorten the processing time required to carry out the sheet feed processing. 
     (A Third Embodiment) 
       FIG. 10  is a diagram illustrating the alignment position. 
     In the present embodiment, the alignment position of the combined roller  20  is a position where the downstream side of the sheet of which the downstream end is abutted against the wall portion  193  of the second cassette  19  is contacted with the combined roller  20 . That is, the alignment position is set to be at the downstream side in the second cassette  19 . 
     In the processing in ACT  13  in  FIG. 7 , the processor  11  enables the moving mechanism  23 A to lift down the combined roller  20  at the standby position to the alignment position, and in this way, the combined roller  20  presses against the downstream side of the sheet. 
     The processor  11  sets the sheet feeding amount by the combined roller  20  at the time of the alignment processing to be slightly greater than the amount of sheet abutted against the wall portion  193 . In the present embodiment, the bending amount of sheet when the sheet is abutted against the wall portion  193  during the alignment processing can be reduced, and a returning amount to the upstream side of sheet after the sheet is abutted against the wall portion  193  can also be reduced. In this way, it is possible to obtain a good precision of alignment processing in the present embodiment. 
     In the present embodiment, since the alignment position of the combined roller  20  is a position where the downstream side of the sheet that is abutted against the wall portion  193  is contacted with the combined roller  20 , the setting precision of the sheet feeding amount can be improved when compared to a case in which the alignment position of the combined roller  20  is a position where the upstream side of the sheet that is abutted against the wall portion  193  is contacted with the combined roller  20 . 
     (A Fourth Embodiment) 
       FIG. 11  is a diagram illustrating the standby position. 
     In the present embodiment, when the combined roller  20  is in a standby state (ACTS  11 ˜ 12  in  FIG. 7 ) until the combined roller  20  moves to and is positioned at the alignment position during the decoloring processing, a moving mechanism  23 A positions the combined roller  20  to the standby position in  FIG. 11  which corresponds to the alignment position and is located above the sheets that are stacked in the second cassette  19  and are not curled. 
     In the present embodiment, if a curl occurs at the downstream end of the discharged sheet, the curl abuts against the combined roller  20  and damages, and then the downstream end of the sheet reaches the lower part of the combined roller  20 . Thus, it is possible to suppress the alignment failure and sheet feed failure very well. 
     (A Fifth Embodiment) 
       FIG. 12  is a flowchart illustrating an alignment processing at the time of a decoloring processing. 
     In the present embodiment, the processing in ACTs  21 ˜ 24  in which the combined roller  20  is positioned at the alignment position to abut against the sheet and the combined roller  20  is also rotated simultaneously is the same as those in ACTs  11 ˜ 14  in  FIG. 7 . 
       FIG. 13  is a diagram illustrating a sheet alignment method by the combined roller  20 . 
     In ACT  25 , the processor  11  enables the moving mechanism  23 A to move the combined roller  20  which is being rotated at the alignment position to the downstream side along the conveyance direction. In this way, the processor  11  moves the sheet to the side of the wall portion  193  at the downstream end of the second cassette  19 , and then the sheet is abutted against the wall portion  193  and aligned. 
     After the combined roller  20  is lifted up by the moving mechanism  23 A under the control of the processor  11 , the processor  11  positions the combined roller  20  at the home position (ACT  26 ). 
     Since the combined roller  20  sends the sheet to the downstream side while being moved to the downstream side in the present embodiment, the time taken to carry out a sheet alignment processing for one sheet can be shortened when compared to a case of sending the sheet to the downstream side while the combined roller  20  is stopped. 
     Further, it is exemplified in the embodiments described above that the image is decolored through the heat; however, the method of carrying out a decoloring processing on an image is not limited to decolor the image through the heat. For example, there may be a method of decoloring the image by coating solvent such as chemicals on the sheet-like image, or a method of decoloring the image by irradiating the image with light. Further, there may also be a method of decoloring an image by peeling off the image formed on a sheet physically. 
     As described above in detail, it is possible to provide a sheet alignment technology and a sheet pickup technology in accordance with the technologies disclosed in this specification. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.