Abstract:
There are provided bookbinding apparatuses that wrap a bundle of sheets with a cover and form back corners, and have a detecting unit for detecting a wave amount of a bundle of sheets. A type of such an apparatus includes a controller to control a time period to form back corners, based on a result of detection by the detecting unit. Another type of such an apparatus includes a controller to control a pressure applied to form back corners based on a result of detection by the detecting unit. Still another type of such an apparatus includes a controller to control a time period and pressure applied to form back corners, based on a result of detection by the detecting unit.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a bookbinding apparatus that binds a book by wrapping a bundle of sheets with a cover, and in particular, to bookbinding quality on the folded portion of a spine.  
       BACKGROUND OF THE INVENTION  
       [0002]     As a bookbinding apparatus that binds a book by wrapping a bundle of sheets with a cover, there has been an apparatus wherein the back of a bundle of sheets and a cover are pasted together with a liquid state adhesive or an adhesive tape. For example, Unexamined Japanese Patent Application Publication No. H09-156249 discloses a means wherein the side edges of the bundle of sheets are lined up on a table, the bundle of sheets thus lined up is clamped at a sheet fixing portion, and the bundle of sheets thus clamped at a sheet fixing portion is caused by a sheet fixed portion moving means to reciprocate between a paste spreading roller that spreads paste on the back of the bundle of sheets and a dryer portion that dries the pasted portion forcibly. Further, Unexamined Japanese Patent Application Publication No. 2004-351726 discloses a means wherein adhesives are sufficiently solidified by measuring ambient temperature after coating adhesives on the back and thereby controlling interposing time for clamping.  
         [0003]     However, in the apparatus that binds a book by wrapping a bundle of sheets with a cover, when bookbinding is performed by wrapping a bundle of sheets with a cover, if the bundle of sheets is sandwiched in a wavy form, there has been a problem that corners of the spine do not become straight lines and the spine does not become flat, even conducting folding formation (back corner forming) of the spine by pressing a cover against the bundle of sheets.  
         [0004]     Means to solve the aforesaid problems is not described in any of the aforesaid Nos. H09-156249 or 2004-351726.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention includes the following structures.  
         [0000]     (1) A bookbinding apparatus that wraps a bundle of sheets with a cover and forms back corners, including:  
         [0006]     a detecting unit for detecting a wave amount of a bundle of sheets; and  
         [0007]     a controller to control a time period to form back corners, based on a result of detection by the detecting unit.  
         [0000]     (2) A bookbinding apparatus that wraps a bundle of sheets with a cover and forms back corners, including:  
         [0008]     a detecting unit for detecting a wave amount of a bundle of sheets; and  
         [0009]     a controller to control a pressing force applied to form back corners, based on a result of detection by the detecting unit.  
         [0000]     (3) A bookbinding apparatus that wraps a bundle of sheets with a cover and forms back corners, including:  
         [0010]     a detecting unit for detecting a wave amount of a bundle of sheets; and  
         [0011]     a controller to control a time period and pressing force applied to form back corners, based on a result of detection by the detecting unit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a front view of a bookbinding apparatus in accordance with an embodiment of the invention;  
         [0013]      FIG. 2  is a diagram showing a process of coating an adhesive;  
         [0014]      FIG. 3  is a diagram showing a movement of a coating head;  
         [0015]      FIG. 4  is a schematic cross-sectional view relating to cover supporting section  90  that supports a cover loading section and a cover;  
         [0016]      FIG. 5  is a schematic perspective view of the cover supporting section viewed from direction A in  FIG. 4 ;  
         [0017]      FIG. 6  is a top view of a cover supporting unit;  
         [0018]      FIG. 7  is a diagram showing how a sheet for a cover is joined with sheets for a book;  
         [0019]      FIG. 8  is a diagram that illustrates processing of a cover after joining; and  
         [0020]      FIG. 9  is a schematic diagram indicating steps up to back corner forming.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]     The invention will be described below, referring to the shown embodiment to which, however, the invention is not limited.  
         [0022]      FIG. 1  is a diagram showing an entire bookbinding apparatus in an embodiment in accordance with the invention.  
         [0000]     &lt;Bookbinding Apparatus&gt; 
         [0023]     Bookbinding apparatus B includes conveying section  10  that conveys sheets S 1  ejected from an image forming device (not shown) to sheet ejection tray  20  or to sheet reversing section  40 , collecting section  50  on which sheets S 1  fed in one by one from the sheet reversing section  40  are stacked, coating unit  60 , cover storing section  80  that stores covers S 2 , cover supporting section  90  that supports a cover and book ejection section  100 .  
         [0024]     Sheet S 1  ejected from the image forming device is ejected, by switching gate  11  provided on the conveying section  10 , to sheet ejection tray  20  through ejection path  12  or to the sheet reversing section  40 . Sheet S 1  is ejected to the sheet ejection tray  20  in a mode other than the bookbinding processing mode.  
         [0025]     A Sheet S 1  is conveyed to the sheet reversing section  40  through conveyance path  13 , and is caused to switchback at the sheet reversing section  40  to be conveyed to the collecting section  50 . In the collecting section  50 , when sheets S 1  in a preset quantity are stacked, a bundle of the sheets S 1  is sandwiched to be rotated, and is supported substantially vertical.  
         [0026]     The coating unit  60  coats an adhesive on the back of the sheets S 1  (a bottom end surface in  FIG. 1 ) supported by the collecting section  50 .  
         [0027]     Cover S 2  comes in contact with the bundle of sheets S 1  on which the adhesive is coated, and is stuck to the bundle of sheets. Thus book S 3  is produced and ejected to the book ejection section  100 .  
         [0028]     Each section of the bookbinding apparatus will be described in detail below.  
         [0029]     Sheet S 1  conveyed through conveyance path  13  is ejected by ejection roller  14 , and is conveyed by oscillating pressure contact roller  401  to rise along tilted reversing tray  402 . After that, the oscillating pressure contact roller  401  rotates reversely to convey the sheet S 1  downward. The sheet S 1  conveyed downward falls onto the collecting section  50  to be stacked thereon.  
         [0030]     The sheet S 1  which has descended along the sheet reversing section  40  is supported obliquely by a sheet supporting unit having supporting plate  502  and stopper plate  506  in the collecting section  50 .  
         [0031]     Sheets S 1  ejected successively from the image forming device are collected on the collecting section  50  to form a bundle of sheets S 1 . The quantity of sheets S 1  forming a bundle is recognized from the quantity of documents inputted by an operator in advance, the quantity of document counted by the use of an automatic document conveyance device mounted on the image forming device or the quantity of documents obtained from document image information transmitted through a personal computer.  
         [0032]     A member  504  restrains lifting of collected sheet S 1 , and it moves off and presses down sheet S 1  each time a single sheet S 1  is supplied to the collecting section  50 . An aligning plate  505  aligns side edges of sheets.  
         [0033]     When sheets S 1  in a preset quantity are collected in the collecting section  50 , holding plate  503  works to sandwich a bundle of sheets S 1  to hold it.  
         [0034]     In a state where the bundle of sheets S 1  is sandwiched and held, the collecting section  50  rotates about an axis of shaft  501  to move the bundle of sheets S 1  to be vertical from its tilted posture.  
         [0000]     &lt;Coating Process&gt; 
         [0035]      FIG. 2  shows a process to coat an adhesive while holding the bundle of sheets S 1  vertically on the collecting section  50 .  
         [0036]     Before showing the coating process, holding of sheets by the holding plate  503  will be described below, referring to diagram (a) of  FIG. 2 .  
         [0037]     Motor M 4  drives to move the holding plate  503  to press a bundle of Sheets S 1 , and when it is detected that a driving torque caused by the pressing reaches a predetermined value, the holding plate  503  stops, thus, the bundle of sheets S 1  is held firmly by the supporting plate  502  and the holding plate  503 . A position for the holding plate  503  to stop is detected by encoder  509  and sensor  510  and stored in a storage device of position detection unit  511 .  
         [0038]     While the bundle of sheets S 1  is being displaced toward the vertical state by rotating the collecting section  50  about the center of shaft  501 , with the bundle of sheets S 1  held, stopper plate  506  is rotated by 90° to retreat as shown in diagram (b) of  FIG. 2 .  
         [0039]     In the state shown by diagram (c) of  FIG. 2 , bottom surface SA of the bundle of sheets S 1  is away from coating roller  63 .  
         [0040]     Next, as shown by diagram (d) of  FIG. 2 , coating unit  60  containing therein hot melt adhesive  653  rises, whereby, coating roller  63  comes in contact with the bottom surface of the bundle of sheets S 1  in the diagram, and moves in the direction perpendicular to the page of  FIG. 2  to coat adhesive  653  on the bottom surface SA of the bundle of sheets S 1 .  
         [0041]     Next, a coating process will be described below, referring to  FIG. 3 .  
         [0042]     In diagram (a) of  FIG. 3 , coating unit  60  is at a right end position (first position) representing a home position at a stage of the start of bookbinding, and at this position, a solid type adhesive is supplied to coating unit  60  through supply path  66 . The solid type adhesive thus supplied is heated and melted by the coating unit  60 . The coating unit  60  moves leftward at the start of bookbinding process from the home position to the left end position (second position), driven by belt  67  (second moving unit) that is driven by motor M 3 , and this movement is started based on a signal which indicates that the front end of the last sheet S 1 , of sheets S 1  to be collected in the collecting section  50 , has been detected to pass, by sheet sensor SE which is provided at the immediate downstream side of reversing tray  402  (see  FIG. 1 ). In the process where the coating unit  60  is moving to the left end position, coating roller  63  is away from the bottom surface of the bundle of sheets S 1 .  
         [0043]     Then, in the stage shown by diagram (b) of  FIG. 3  where the coating unit  60  moves toward a right end position from the left end position, coating roller  63  is driven by motor M 2  to rise, and to come in contact with the bottom surface of sheet S 1  to coat adhesive  653 . With respect to the start of the coating process in diagram (a) of  FIG. 3 , timing of the process is controlled to start coating after the stop of conveyance of a cover that is cut by cutter  81  after the bundle of sheets S 1  is set to the state allowing vertical coating. Herein, the right end position of coating unit  60  in  FIG. 3  is a position on the back side of the apparatus when the apparatus is viewed from the front side of the sheet of  FIG. 1 , and the left end position of coating unit  60  in  FIG. 3  is a position on the front side of the apparatus when the apparatus is viewed as the same.  
         [0044]     Owing to this timing control, operations of respective portions are carried out sequentially, and bookbinding process is performed at high efficiency. After the coating unit  60  is moved to its home position, cover S 2  is joined.  
         [0000]     &lt;Joining Process&gt; 
         [0045]     Next, the joining process for a bundle of sheets S 1  and cover S 2  will be described below, referring to  FIGS. 4-8 .  
         [0046]      FIG. 4  is a schematic sectional view relating to cover storing section  80  that stores covers S 2  and relating to cover supporting section  90  that supports a cover, while  FIG. 5  is a schematic perspective view wherein the cover supporting section  90  in  FIG. 4  is viewed in the direction A in  FIG. 4 .  
         [0047]     As shown in  FIG. 4 , a cover S 2  is stored in sheet feeding tray  801  of the cover storing section  80  provided at a lower part of the bookbinding apparatus, and it is fed by sheet feeding/conveyance roller  82 , and then, caused to switchback after being aligned by the cover supporting section  90 , to be cut by cutter  81  being a cutting unit to the length corresponding to the bundle of sheets S 1 , and is conveyed by conveyance roller  84  to be placed horizontally on cover supporting unit  901  that is shown with one-dot chain lines. The cover supporting unit  901  includes a plurality of members such as pressing members  91  and  92  and cams  93  and  94  which drive the pressing members  91  and  92 .  
         [0048]     In the mean time, the cutter  81  cuts the cover S 2  to the length based on information of the size of the cover S 2 , information on the size of sheet S 1  and on information on a thickness of a bundle of sheets S 1  stored in position detection unit  511 . Scraps of the cover S 2  are put into a storage box  83 .  
         [0049]     The cover S 2  cut to a certain length is fed out by conveyance roller  84  to be inserted into a clearance of about 5 mm provided between upper guide plate  955  and lower guide plate  956 . The cover S 2  is conveyed by cover conveyance rollers  951  and driven by rollers  952  which are provided respectively at the tips of cover holding members  95  and  96 . The cover S 2  is controlled to stop when it comes to a certain position based on information on its size and on information on a thickness of a bundle of sheets S 1 . Cover holding members  97  moves into a space under the cover to lift the cover.  
         [0050]      FIG. 6  is a top view of the cover supporting unit  901 .  
         [0051]     Belts  98 A and  98 B conduct aligning operations to correct inclination of conveyed cover S 2  and convey the bound book S 3  to book ejection section  100 .  
         [0052]     For the purpose of setting cover S 2  at a predetermined position, there are provided aligning members  981 A and  981 B which align both edges of the cover S 2  in the direction parallel to the conveyance direction of the cover S 2 . Further, on aligning members  981 A and  981 B, there are provided respective belts  98 A and  98 B and drum-shaped rollers which support the belts  98 A and  98 B with tension, and they are movable in the direction of both edges of the cover. The aligning members  981 A and  981 B conduct aligning operation each time the cover S 2  is conveyed. In the aligning operations, both edge portions of the cover move into clearances under the belts  98 A and  98 B respectively, and respective edge portions are hit slightly to be aligned by aligning members  981 A and  981 B. Further, when cover supporting unit  901  which will be described later rises, aligning members  981 A and  981 B as well as belts  98 A and  98 B are retreated to the position shown with two-dot chain lines in  FIG. 6 , so that the belts  98 A and  98 B are retracted from above the cover S 2  to avoid a collision.  
         [0053]      FIG. 7  shows the state where belts  99 A and  99 B (first moving unit) are driven by motor M 10 , in a state where the cover S 2  is raised together with the cover supporting unit  901  while the cover S 2  is pressed downward by pressing members  95  and  96 .  
         [0054]     Diagram (a) of  FIG. 7  shows the state where coating of adhesive  653  has been completed. In the state of diagram (a) of  FIG. 7 , the cover supporting unit  901  is supporting the cover S 2  at the lower position that is away from the bottom surface of the bundle of sheets S 1 , as shown in  FIG. 4 .  
         [0055]     When the cover supporting unit  901  starts to rise, the cover holding members  95  and  96  are holding the cover S 2  downward to hold the cover S 2  to be flat. Before the cover S 2  rises and comes in contact with surface SA of the bundle of sheets S 1 , motor M 9  (see  FIG. 5 ) releases the contact of the cover holding members  95 ,  96  and  97  with the cover S 2 , and the state shown by diagram (b) of  FIG. 7  is created. In this case, a state is created where the cover S 2  is lifted up by the cover holding member  97  that has moved into a space under the cover S 2 .  
         [0056]     The cover supporting unit  901  further rises by several millimeters from the position shown by diagram (b) of  FIG. 7 . The cover supporting unit  901  is lifted by several millimeters to the position shown by diagram (c) in  FIG. 7 . After rising, pressing members  91  and  92  press the cover S 2  from its both sides to create corners at the boundary between the spine and the front cover and at the boundary between the spine and the back cover, thus, the cover S 2  is brought into close contact with the bundle of sheets S 1 , and book S 3  is formed.  
         [0057]     The pressing members  91  and  92  are moved in the horizontal direction by cams  93  and  94  (see  FIG. 6 ) driven by a motor (not shown). Incidentally, the pressing members  91  and  92  may also be moved by rotation of a pinion that engages with a rack provided on each member.  
         [0058]     Processing of the cover S 2  after joining will be described below, referring to  FIG. 8 .  
         [0059]     After joining of the cover S 2  is completed, the pressing members  91  and  92  are released, and the cover supporting unit  901  is lowered by about 100 mm by the drive of belts  99 A and  99 B to return to its home position, as shown by diagram (a) of  FIG. 8 . Then, the cover S 2  is lifted by about 50 mm on its left and right sides in such a manner that cover holding members  95 ,  96  and  97  become horizontal from their vertical state once and then are rotated reversely again, and cover lifting member  971  is also lifted.  
         [0060]     Then, belts  98 A and  98 B are moved to positions inside the width of the cover S 2 , and the cover supporting unit  901  is lifted about 70 mm.  
         [0061]     Holding plate  503  moves to its retracted position to release the pressing, whereby, book S 3  having a bundle of sheets S 1  and cover S 2  falls onto belts  98 A and  98 B. Then, motor M 8  (see  FIG. 5 ) is driven to circulate belts  98 A and  98 B while the cover supporting unit  901  is lowered again, to bring the book S 3  down while transporting it to the book ejection section  100  side. Herein, the cover holding members  96  and  97  are rotated greatly in the rising direction as shown in diagram (c) of  FIG. 8  to lift the cover on the left side. When the cover supporting unit  901  arrives at its home position (diagram (d) of  FIG. 8 ), the book S 3  is sent by belts  98 A and  98 B to the left end, to be ejected to book ejection section  100  as it is.  
         [0062]     Sheet ejection table  101  is lifted and lowered, driven by a belt. The sheet ejection table  101 , on which book S 3  is loaded, is lowered to deliver the book S 3  to belt  102 , and belt  102  conveys the book S 3  to eject it from the bookbinding apparatus.  
         [0000]     &lt;Wave Amount&gt; 
         [0063]     Now, a wave amount detection unit will be described. In general, an image forming device employing an electrophotographic system has therein a fixing unit that heats and fixes toner images transferred on a sheet. When toner images are heated and fixed, moisture contained in the sheet S 1  itself evaporates, and sheet S 1  shrinks and waves are generated when the sheet S 1  is ejected out of the device.  
         [0064]     Therefore, there is generated a difference between an actual thickness of a bundle of sheets calculated from a value stored in a storage device of position detection unit  511  (see  FIG. 2 ) and a theoretical thickness of the bundle of sheets obtained by a product of a thickness per sheet and a counted quantity of sheets, such as a quantity of document sheets counted by an automatic document conveyance unit of the aforesaid image forming device. This difference is referred to as a wave amount. In other words, when the wave amount is great, the actual measurement value is much greater than the theoretical value, while, when the wave amount is substantially zero, the actual measurement value is substantially the same as the theoretical value.  
         [0065]     If a value of this wave amount is great, there is caused a problem that a corner section (referred to as a book corner section) formed on each of the boundary between a spine and a front cover and the boundary between the spine and a back cover does not result in a straight line, and irregularities are generated on a flat section of the spine to decline quality of bookbinding.  
         [0066]     To solve this problem, the pressing time period with pressing members was made variable, corresponding to the wave amount. Table 1 shows values of relationship between the pressing time (back corner forming time) with pressing members  91  and  92  which press the cover S 2  from both sides thereof and the wave amount, the values being obtained from experiments.  
         [0067]     The bookbinding apparatus has a control unit which has therein incorporated data of Table 1 and performs control so that back corners can be properly formed, making the back corner forming time automatically variable based on the data.  
                           TABLE 1                                   Wave amount W (mm)   Back corner forming time (sec.)                           0 ≦ W &lt; 3   10           3 ≦ W &lt; 7   15           7 ≦ W   20                      
 
         [0068]     In Table 1, when the wave amount is smaller than 3 mm, for example, the back corner forming time is 10 sec. When the wave amount is not smaller then 3 mm and smaller than 7 mm, the back corner forming time is 15 sec, and when the wave amount is 7 mm or greater, the back corner forming time is 20 sec. Motor M 4  that rotates cams  93  and  94  is driven until the moment when the current value of the motor M 4  reaches a predetermined limit current value, to press a bundle of sheets and cover S 2  with pressing members  91  and  92 . After keeping the stopping state of the motor M 4  such that the state of this pressing is kept for the back corner forming time corresponding to each wave amount, the motor M 4  is driven again to release the pressing. In the case of the aforesaid mechanism to move the pressing members  91  and  92  by the rack and pinion, the motor M 4  that rotates the pinion is driven until the moment when a current value of the motor M 4  reaches a predetermined limit current value, to press a bundle of sheets and the cover S 2  with the pressing members  91  and  92 . After keeping the state of pressing for the back corner forming time corresponding to each wave amount, the pinion is rotated reversely by the reverse rotation of the motor M 4  to release the pressing.  
         [0069]     As a device to form proper back corners, a device to control a pressing force given to the pressing members  91  and  92  may also be used, in addition to the device to control the aforesaid back corner forming time. The pressing force can be controlled through the control of limit current that drives motor M 4 . Table 2 shows values of experiments wherein the limit current value is converted to the pressing force.  
                               TABLE 2                                   Wave amount W (mm)   Pressing force (N)   Current value                           0 ≦ W &lt; 3   200   1.5 A           3 ≦ W &lt; 7   300   2.0 A           7 ≦ W   400   2.5 A                      
 
         [0070]     In Table 2, when the wave amount is smaller than 3 mm, for example, the required pressing force is 200 N (Newton). When the wave amount is not smaller than 3 mm and smaller than 7 mm, the pressing force is 300 N, and when the wave amount is 7 mm or greater, the pressing force is 400 N. Motor M 4  that rotates cams  93  and  94  continues to be driven until the moment when a current value of the motor M 4  reaches a limit current value corresponding to each wave amount. When the current value of the motor M 4  reaches a limit current value, the motor M 4  is stopped so as to keep the state of pressing with the pressing members  91  and  92  for a predetermined time, and then, the motor M 4  is driven again to release the pressing. Further, in the case of the mechanism to move pressing members  91  and  92  with a rack and a pinion as mentioned above, the motor M 4  continues to be driven until the moment when the driving current value of the motor M 4  that rotates the pinion reaches a limit current value corresponding to each wave amount. When the current value of the motor M 4  reaches a limit current value, the motor M 4  is stopped so as to keep the state of pressing for a predetermined time, and then, the motor M 4  is rotated reversely to release the pressing.  
         [0071]     Further, as shown in Table 3, it is possible to shorten the back corner forming time by controlling both the back corner forming time and the limit current value. Thus, the bookbinding time is shortened, resulting in an improvement of productivity.  
                                                 TABLE 3                                           Back corner forming           Wave amount W (mm)   Pressing force (N)   time (sec.)                                        0 ≦ W &lt; 3   200   7           3 ≦ W &lt; 7   300   10           7 ≦ W   400   15                      
 
         [0072]     Namely, after starting the drive of motor M 4  that rotates cams  93  and  94  or a pinion, the drive is continued until the moment when the current value reaches the limit current value corresponding to each wave amount, then the drive is stopped at a point of time when the current value reaches the limit current value, and the state of the stopping is kept for the back corner forming time corresponding to each wave amount. After that, the drive of the pressing members  91  and  92  is released.  
         [0073]      FIG. 9  is a schematic diagram indicating the flow up to conducting back corner forming. A quantity of sheets is recognized, as described above, according to the quantity of documents which has been automatically counted or has been input by an operator via an operation section, not shown, of an image forming device or an image input device such as a personal computer. A type of sheets is input by the operator as well. Regarding sheet types, sheet thicknesses for plain paper, coated paper, etc. are stored in a storage device in advance. At the point of time when the quantity of sheets is inputted, a thickness of a bundle of sheets is calculated.  
         [0074]     A wave amount is calculated based on an actual thickness of a bundle of sheets calculated from a value stored in a storage device of position detection unit  511 , and based on a thickness of a bundle of sheets calculated theoretically. The operation time period of motor M 4  and/or the limit current value is controlled according to values in Table 1, Table 2 or Table 3.  
         [0075]     Bookbinding that forms straight book corner sections and a flat section of the spine without irregularities has been attained, with a device to detect the wave amount, and through control of either the time period or the pressing force to form back corners or through control of the both, based on the result of the detection of the wave amount.  
         [0076]     In the present embodiment, it is possible to provide a bookbinding apparatus that allows binding a high quality book wherein corners of a spine after bookbinding are straight and the spine is flat, by detecting the wave amount of a bundle of sheets and controlling folding processing of the spine based on the result of the aforesaid detection.