Patent Publication Number: US-2010129128-A1

Title: Bookbinding apparatus and image forming system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based on Japanese Patent Application No. 2008-302,189 filed on Nov. 27, 2008, with the Japanese Patent Office, the entire content of which is hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a bookbinding apparatus and an image forming system using the same apparatus. 
     The above image forming system includes an image forming apparatus which forms an image on a recording sheet, and includes a bookbinding apparatus which receives the recording sheet, on which the image has been formed by the image forming apparatus, from the image forming apparatus, and conducts a bookbinding process onto the recording sheet. 
     BACKGROUND OF THE INVENTION 
     In printing fields, referred to as a POD (being print on demand), books are produced by the image forming system, structured of the image forming apparatus and the bookbinding apparatus, while printing plates are not formed. 
     Most of the bookbinding apparatus for the POD, as disclosed in Unexamined Japanese Patent Application Publication No. 2008-80,603 (hereinafter referred to as “Patent Document 1”), in order to bind a bundle of sheets (hereinafter referred to as a “sheet-bundle”), an adhesive applying device is used. Since the adhesive applying device is simply structured, and small-sized, said device is suitable to combine with the image forming apparatus. 
     Regarding above Patent Document 1, in an adhesive coating device, including an adhesive container heater and a coating section heater, after a temperature of the adhesive container heater, a temperature of the coating section heater, and a temperature of the adhesive have been individually detected, the adhesive container heater and the coating section heater are individually controlled, whereby the temperature of the adhesive in the container is controlled to a uniform temperature, and the adhesive is quickly melted. 
     In Unexamined Japanese Patent Application Publication No. H10-35,138 (hereinafter referred to as “Patent Document 2”), the number of heaters is configured to differ in a warm-up time and a coating time, so that the warm-up time is shortened and electrical energy consumption is minimized. 
     As above Patent Document 2 discloses, the waiting time must be reduced, which time is between a starting time of the adhesive heating section and a time in which a coating operation can be conducted, in which the adhesive has been melted, that is, reduction of said waiting time has been a great technical matter to be solved. 
     The waiting time is a warm-up time to heat the adhesive to a temperature in which a coating operation can be conducted, after the adhesive heating section has been activated. In Patent Documents 1 and 2, a plurality of heaters, used as a heating means, are individually controlled, so that the warm up time may be reduced. 
     However, the above described methods to reduce the warm-up time have their own limitations, whereby the warm-up time cannot be sufficiently reduced. Further, like Patent Document 2, if a heater, which is activated only during the warm-up time, is employed, the electrical energy consumption is increased during the warm-up time, whereby maximum electrical power of the apparatus cannot but increase. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is detailed below. A bookbinding apparatus, which binds a bundle of sheets with an adhesive, and forms a booklet, including: 
     an adhesive tank which is configured to store the adhesive; 
     a heating section to heat and melt the adhesive stored in the adhesive tank; 
     an adhesive supplying member which is configured to be submerged in the adhesive stored in the adhesive tank, and to be rotated to supply the adhesive onto a coating portion of the bundle of sheets; and 
     a control section which controls the adhesive supplying member to rotate, in at least one interval during a warm-up process in which the adhesive is heated to a predetermined temperature by the heating section after the heating section has been activated. 
     According to the above aspect, another aspect is an image forming system, including: 
     an image forming apparatus which is configured to form an image on a sheet; and 
     the bookbinding apparatus described in the above aspect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiment will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in the several figures, in which: 
         FIG. 1  shows a total structure of an image forming system relating to the embodiment of the present invention; 
         FIG. 2  shows a cross-sectional view of a bookbinding apparatus relating to the embodiment of the present invention; 
         FIG. 3  shows a structure of adhesive coating section  50 ; 
         FIG. 4  shows roller heater H 2  coupling to adhesive coating roller  51 ; 
         FIG. 5  is a block diagram of a control system to heat the adhesive in the bookbinding apparatus relating to the embodiment of the present invention; 
         FIG. 6  is a flow chart to detail a heating procedure of the adhesive, and 
         FIG. 7   a  shows the change of the temperature of adhesive during the warm-up time, controlled by the conventional art, and 
         FIG. 7   b  shows the change of the temperature of adhesive during the warm-up time, controlled by the present invention. 
     
    
    
     DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will now be detailed while referring to the drawings, but the present invention is not limited to the embodiment. 
       FIG. 1  shows a total structure of an image forming system relating to the embodiment of the present invention. 
     The image forming system shown in  FIG. 1  includes image forming apparatus A and bookbinding apparatus B. In the present embodiment, bound booklet storing apparatus C follows bookbinding apparatus B. After booklet storing apparatus C receives bound booklet S 3 , formed by bookbinding apparatus B, booklet storing apparatus C conveys bound booklet S 3  using belt  91 , and stores it on wheeled platform  92 . 
     &lt;Image Forming Apparatus A&gt; 
     Image Forming Apparatus A to form an image using an electro-photographic process includes an image forming section, in which electrical charging section  2 , image exposure section  3 , developing section  4 , image transfer and discharging section  5 , and cleaning section  6 , are arranged around rotating photoconductor  1 . 
     The image forming section evenly applies an electrostatic charge onto a surface of photoconductor  1 . After that, the image forming section conducts exposure scanning, based on targeted image data, using laser beams emitted from image exposure section  3 , and forms a latent image. Subsequently, the image forming section conducts reversal development for the latent image using developing section  4 , whereby a toner image is formed on the surface of photoconductor  1 . 
     Recording sheet S, which is supplied from sheet storing section  7 A, is conveyed to a transfer position. At said position, the targeted toner image is transferred onto recording sheet S by transfer and discharging section  5 . After that, any electrical charges remaining on recording sheet S are eliminated, and recording sheet S is then separated from photoconductor  1 . Said image carrying recording sheet S is conveyed to fixing section  8  by conveyance section  7 B, at which, said recording sheet S is heated to fix the image, and sheet S is then ejected to bookbinding apparatus B, by ejection roller  7 C. 
     To form images on both surfaces of recording sheet S, recording sheet S, carrying one image fixed by fixing section  8 , is conveyed by conveyance path switching section  7 , to a conveyance path, which is branched from a normal ejection path. Recording sheet S is then switched back by reversing conveyance section  7 E, so that recording sheet S is reversed by the switch-back movement, subsequently said recording sheet S is re-conveyed to the above described transfer position, whereby, a new image is formed on the reverse surface of recording sheet S. 
     Recording sheet S, carrying the two images fixed by fixing section  8  on both of its surfaces, is ejected to the outside of the apparatus through paired ejection rollers  7 C. Said recording sheet S is then conveyed to bookbinding apparatus B. 
     After the image formation, any remaining toner particles are removed from the surface of photoconductor  1 , by cleaning section  6 , and photoconductor  1  stands by for next image formation. 
     Operation display section  9 , including an input section and a display section, is provided on an upper section of image forming apparatus A. 
     &lt;Bookbinding Apparatus B&gt; 
     Bookbinding apparatus B will now be detailed while referring to  FIGS. 1 and 2 .  FIG. 1  shows a cross-sectional structure of bookbinding apparatus B. 
     Bookbinding apparatus B is structured of sheet conveyance section  10 , sheet storage section  20 , sheet-bundle storing section  30 , sheet-bundle conveyance section  40 , adhesive coating section  50 , cover sheet supplying section  60 , cover sheet cutting section  70 , cover sheet supporting section  80 , and operation display section  90 . 
     Sheet S, which has been conveyed from image forming apparatus A to sheet conveyance section  10 , is further conveyed to any one of sheet storage section  20 , sheet-bundle storing section  30 , and cover sheet supporting section  80 , by plural sets of conveyance rollers, and a conveyance path switching gate. If no bookbinding process has been ordered, the conveyance path switching section is determined to be a non-bookbinding operation, whereby sheets S, conveyed from image forming apparatus A, are sequentially ejected onto a sheet storage tray of sheet storage section  20 . 
     If a bookbinding process has been ordered by the user, sheet S, on which a fixed image has been formed by image forming apparatus A, is conveyed by sheet conveyance section  10 , to sheet-bundle storing section  30 , that is, plural sheets S are subsequently stacked on sheet-bundle storing section  30 , whereby said stacked sheets are jogged to become sheet-bundle S 1 . 
     Sheet-bundle S 1  is conveyed by sheet-bundle conveyance section  40 , after that, adhesive is applied onto back Sa of sheet-bundle S 1  by adhesive coating section  50 , wherein back Sa serves as a coating portion. 
     Onto back Sa of sheet-bundle S 1 , on which adhesive has been already applied, cover sheet S 2  is placed, while being supported by cover sheet supporting section  80 . After that, cover sheet S 1  is folded along both edges of back Sa, whereby booklet S 3  is produced. 
     Sheet-bundle storing section  30  includes sheet stacker  35 , which is slanted, movable trailing edge positioning member  36 , alignment member  37 , which aligns all sheets of sheet-bundle S 1  with respect to the width of sheet-bundle S 1 , and the like members. 
     Sheets S, which have been conveyed by sheet conveyance section  10  from image forming apparatus A, are subsequently placed on sheet stacker  35 . After a predetermined number of sheets S are stocked, sheet-bundle S 1  is formed. 
     After sheet-bundle S 1  has been jogged and aligned on sheet stacker  35  of sheet-bundle storing section  30 , sheet-bundle S 1  is nipped by opposed nipping sections  41 . After that, trailing edge positioning member  36  is retracted under sheet stacker  35  by a driving section, which is not illustrated. 
     After opposed nipping sections  41  have nipped sheet-bundle S 1 , said sections  41  move downward obliquely, as shown by dotted lines in  FIG. 2 . Subsequently, opposed nipping sections  41  turn vertically, whereby back Sa of sheet-bundle S 1  is turned with the back downward, and opposed nipping sections  41  stop at this position, being a predetermined position. 
     A cover sheet S 2 , which has been stored in cover sheet accommodating section  61  of cover sheet supplying section  60 , is picked and conveyed by sheet supplying section  62  through paired conveyance rollers  63 ,  64  and  65 , and then further conveyed by conveyance rollers  81  and  82  of cover sheet supporting section  80 , to a predetermined position, where cover sheet S 2  stops. 
     If the length of cover sheet S 2  is greater than the length to conduct a case binding of sheet-bundle S 1 , cover sheet S 2  is cut by cover sheet cutting section  70 , which is located at the right of conveyance roller  65  in  FIG. 2 , so that an extra portion of cover sheet S 2  is removed in advance. 
     Adhesive coating section  50  is provided on movable body  54 , which is supported by guiding rods  55 , whereby adhesive coating section  50  moves perpendicularly on the page surface of  FIG. 2 . Since a home position of movable body  54  is provided in the rear of book binding device B, movable body  54  moves to the front, to conduct the adhering operation. 
     Adhesive coating roller  51 , serving as an adhesive supplying member, is driven along back Sa of sheet-bundle S 1  by motor M and driving system  52 , that is, adhesive coating roller  51  moves perpendicularly on the page surface of  FIG. 2 . 
     Cover sheet supporting section  80  goes up and down by elevating section  86 . 
     After movable body  54  has been driven forward from the home position to the front, adhesive coating roller  51  reciprocates in arrowed directions W 2  and W 3  (see  FIG. 3 , which will be detailed later), due to motor M, so that adhesive is coated onto back Sa of sheet-bundle S 1 . 
     After the coating operation has been finished, movable body  54  returns to the home position, and cover sheet supporting section  80  rises to adhere cover sheet S 2  onto back Sa. Pressing section  83  is then driven to firmly press against back Sa. 
     Booklet S 3 , which has been formed by adhering cover sheet S 2  onto sheet-bundle S 1 , is conveyed by belt  87  to booklet storing device C. 
     &lt;Adhesive Coating Section&gt; 
       FIG. 3  shows adhesive coating section  50 . Adhesive coating section  50  includes adhesive tank  53  to store melted liquid adhesive N, adhesive coating roller  51 , serving as the adhesive supplying member, regulation members  503  and  504 , tank heater H 1 , serving as a first heater to heat the adhesive, roller heater serving as a second heater to heat the adhesive, adhesive thermal sensor TS 1 , and remaining adhesive amount sensor  506 . 
     In  FIG. 3 , the adhesive supplying member is structured of adhesive coating roller  51 . However, an adhesive applying bar may also be used as another structure. A rotating adhesive supplying member supplies the adhesive onto said bar, that is, the adhesive coating member and the adhesive supplying member can be formed as different members. 
     Tank heater H 1  is provided at the bottom portion of adhesive tank  53  as shown in  FIG. 3 , so that tank heater H 1  heats the total adhesive in adhesive tank  53 . 
     Roller heater H 2  heats shaft  51 A of adhesive coating roller  51 , which is shown in  FIG. 4 . Shaft  51 A is formed of metal, adhesive coating roller  51  is totally heated through shaft  51 A, which is heated by roller heater H 2 , whereby the adhesive existing on adhesive coating roller  51  is heated. 
     Adhesive N, being in a pellet state, is supplied to adhesive tank  53  by a supplying device, which is not illustrated. 
     The adhesive in the pellet state is heated so that adhesive N is liquefied. 
     Based on signals sent from remaining adhesive amount sensor  506 , adhesive N is supplied from the supplying device to adhesive tank  53 , whereby a stable surface level of the liquid adhesive N is ensured. 
     Regulation member  503  is formed of a round rod, and regulation member  504  is mounted on supporting plate  507 , that is, both ends of regulation member  504 , being other than the coating area, are attached to supporting plate  507  by screws. 
     Regulation member  504  serves as a scraping section, which is structured of main scraping section  504 A and sub-scraping section  504 C, to scrape the adhesive, coated on back Sa of sheet-bundle S 1  by adhesive coating roller  51 , to a predetermined thickness. 
     Regulation member  504 D controls the thickness of the adhesive layer on adhesive coating roller  51 . 
     Regulation member  503 , which is a rod member to control the thickness of the applied adhesive, is provided opposite above regulation member  504 , with adhesive coating roller  51  in between. 
     Adhesive coating roller  51  is rotated in arrowed direction W 1  by a motor, which is not illustrated, and reciprocates in arrowed directions W 2  and W 3  by motor M (see  FIG. 2 ), so that adhesive coating roller  51  applies the adhesive onto back Sa of sheet-bundle S 1 , via the reciprocating movement. 
     During the movement in arrowed direction W 2 , the amount of adhesive on back Sa is controlled by regulation member  503 , while during the movement in arrowed direction W 3 , the amount of adhesive on back Sa is controlled by regulation member  504 , whereby the adhesive layer exhibiting the even thickness is formed on back Sa. 
     &lt;Control during the Warm-up Procedure) 
     The warm-up time interval is typically several minutes to several tens of minutes, which is from the time when tank heater H 1  is activated, to the time when adhesive N is completely melted as a coating state. 
     In order to improve the working efficiency of the bookbinding apparatus, the reduction of the warm-up time interval is one of the important problems for its development. 
     In the present invention, the adhesive is heated, while the adhesive supplying member is rotated, so that the temperature raising is speeded up, that is, the warm-up time interval can be decreased. 
       FIG. 5  is a block diagram of a control system to heat the adhesive in the bookbinding apparatus relating to the embodiments of the present invention, and  FIG. 6  is a flow chart to detail a heating control procedure of the adhesive. 
     Control section CR conducts an ON-OFF control for tank heater H 1  and roller heater H 2 , based on the output of thermal sensor TS 1  to detect the temperature of the adhesive stored in adhesive tank  53 , and based on the output of thermal sensor TS 2  to detect the temperature of adhesive coating roller  51 . 
     In this case, adhesive thermal sensor TS 1 , shown in  FIG. 3 , is submerged in adhesive N stored in adhesive tank  53 , so that said sensor TS 1  is able to continually detect the temperature of adhesive N. Further, adhesive thermal sensor TS 2  is provided within adhesive coating roller  51 , so that said sensor TS 2  detects the operating temperature of the adhesive layer on adhesive coating roller  51 . 
     In step ST 1  of  FIG. 6 , tank heater H 1  and roller heater H 2  are electrically activated as a start of heating. 
     In step ST 2 , control section CR determines whether the temperature detected by adhesive thermal sensor TS 1  has reached the melting point of the adhesive (for example, 90° C.), and if it has reached, the control to rotate adhesive coating roller  51  is started in step ST 3 . 
     Otherwise, the starting time of the control to rotate adhesive coating roller  51  may be after a predetermined time interval from “ON” of step ST 1 . Said predetermined time interval is experimentally determined to measure the time interval between the time of heater “ON” and the time when the adhesive temperature has reached its melting point. 
     If adhesive coating roller  51  is controlled to rotate before the temperature of the adhesive has reached its melting point, the motor to rotate adhesive coating roller  51  may become too load, which can adversely result in a damaged motor. Accordingly, until the temperature of the adhesive reaches its melting point, adhesive coating roller  51  is controlled not to rotate. After the melting point has been obtained, adhesive coating roller  51  is controlled to rotate, whereby adhesive coating roller  51  can rotate smoothly within melted adhesive N in adhesive tank  53 . 
     The rotation control shown in step ST 3  represents an intermittent control, in which adhesive coating roller  51  is controlled to rotate in 2-3 sec., and not to rotate in 2-3 sec., which control sequence is repeated. 
     Due to the rotation control of step ST 3 , adhesive N is desirably agitated in tank  53 , for which reason, adhesive N has been heated evenly and quickly. 
     In step ST 4 , the temperature of adhesive coating roller  51  is monitored by adhesive thermal sensor TS 2 , whether the temperature is on an upper limit, or approaching it. If it is on the upper limit, roller heater H 2  is deactivated. The upper limit of the temperature of adhesive coating roller  51  represents the highest temperature at which adhesive N does not change its inherent physical properties, said temperature is set at 185° C., for example. 
     When the temperature of adhesive coating roller  51  has reached the upper limit (“Yes” of step ST 4 ), roller heater H 2  is controlled to deactivate (step ST 5 ). However, tank heater H 1  is still activated. 
     In step ST 6 , the adhesive temperature, detected by adhesive thermal sensor TS 1 , is monitored whether it has reached the coating temperature. 
     The coating temperature is typically set, for example, at 165° C. 
     In step ST 6 , if the temperature of adhesive N, stored in adhesive tank  53 , reaches the coating temperature, the warm-up procedure is completed. 
     After the completion of warm-up procedure, tank heater is controlled, which control is not illustrated in  FIG. 6 , to be “ON” and “OFF”, so that the temperature of adhesive N in adhesive tank  53  is kept to be the coating temperature. 
       FIG. 7  shows the change of the temperature of adhesive N during the warm-up procedure. 
       FIG. 7   a  shows the change of the temperature of the adhesive, controlled by the conventional art, while  FIG. 7   b  shows the changes of the temperature of the adhesive, controlled by the embodiment shown in the present invention. 
     The control, conducted by the conventional art, will now be detailed. 
     Adhesive coating roller  51  is controlled to deactivate, during the warm-up procedure of the conventional art. However, the tank heater and roller heater have also been used in the conventional art. 
     In  FIG. 7   a , tank heater H 1  and roller heater H 2  are controlled to start heating at time to. 
     Since the adhesive on adhesive coating roller  51  is heated by tank heater H 1  and roller heater H 2 , an appreciation rate of the temperature of the adhesive on the coating roller is greater than that of the adhesive stored in adhesive tank  53 , whereby the temperature of the adhesive on the coating roller quickly rises as shown in curve L 1 , which is like a straight line. 
     When the temperature of the adhesive on adhesive coating roller  51  has reached coating temperature U 0  at time t 1 , roller heater H 2  is controlled to change from continuous “ON” activation to continuous “ON and OFF” activation. Due to the “ON and OFF” control after time t 1 , the temperature of the adhesive on adhesive coating roller  51  is controlled to keep coating temperature U 0 . 
     On the other hand, the temperature of the adhesive in adhesive tank  53  rises slowly as shown by curve L 2 , and reaches coating temperature U 0  at time t 2 . 
     After time t 2 , tank heater H 1  is controlled to be “ON and OFF”, so that the temperature of the adhesive in adhesive tank  53  is kept to be coating temperature U 0 . 
     According to the present invention, tank heater H 1  and roller heater H 2  are activated to simultaneously start heating at time t 0 , which is shown in  FIG. 7   b.    
     Since the adhesive on adhesive coating roller  51  is heated by tank heater H 1  and roller heater H 2 , an appreciation rate of temperature rise of the adhesive on adhesive coating roller  51  is greater than that of the adhesive stored in adhesive tank  53 , whereby the temperature of the adhesive on the coating roller quickly rises as shown by curve L 3 , which is like a straight line. 
     When the temperature of the adhesive on adhesive coating roller  51  reaches upper limit temperature U 1  at time t 11 , roller heater H 2  is deactivated. 
     On the other hand, the temperature of the adhesive in adhesive tank  53  rises slowly as shown by line L 4   a , and reaches melting point U 2  of the adhesive at time t 10 . 
     When the temperature of the adhesive in adhesive tank  53  reaches melting point U 2  at time t 10 , the control to rotate adhesive coating roller  51  is started. That is, adhesive coating roller  51  is controlled to repeat “rotation” and “stop”, so that adhesive N in adhesive tank  53  is agitated. 
     Due to the agitation of adhesive N, the appreciation rate of temperature of adhesive in tank  53  becomes greater as shown by line L 4   b  of curve L 4 . 
     When the temperature of the adhesive in tank  53  has reached coating temperature U 0  at time t 12 , tank heater H 1  is controlled to repeat “ON” and “OFF”. Due to the repeated “ON and OFF” control, the temperature of the adhesive within adhesive tank  53  is controlled to keep coating temperature U 0 . 
     As shown in  FIG. 6 , when adhesive thermal sensor TS 1  has detected that the temperature of adhesive N in adhesive tank  53  has reached the coating temperature, the warm-up procedure is completed. 
     In  FIG. 7   b  showing the embodiment of the present invention, the warm-up procedure is completed at time t 12 , which time is approximately 10 minutes after the start of warm-up. 
     However, in the conventional art shown in  FIG. 7   a , the warm-up time requires 15 minutes, which is longer than  FIG. 7   a.    
     The reduction of the warm-up time, shown in  FIG. 7   b , contributes to the rotation of adhesive coating roller  51 , and yet contributes to the fact that roller heater H 2  keeps the temperature of the adhesive on adhesive coating roller  51  at the upper limit temperature which is higher than the coating temperature. 
     That is, the overly heated adhesive on adhesive coating roller  51  is mixed with the lower temperature adhesive in adhesive tank  53 , by the rotation of adhesive coating roller  51 , whereby the temperature of adhesive N in adhesive tank  53  is more rapidly raised so that the warm-up time can be reduced. 
     Accordingly, due to the present invention, the warm-up time can be reduced considerably. 
     In the image forming system, the waiting time of image forming apparatus A is shorter than that of bookbinding apparatus B, whereby the total operational efficiency of the image forming system depends upon the waiting time of bookbinding apparatus B. By the present invention, since the waiting time of bookbinding apparatus B is reduced, the operational efficiency of the image forming system is considerably improved. 
     Concerning the effect of the invention, based on the present aspect, the adhesive in the adhesive tank is agitated during the warm-up procedure. Due to this agitation, the temperature distribution of the adhesive in the adhesive tank becomes more even, whereby the adhesive is more equally heated, so that the rising time of temperature of the adhesive in the tank is shortened, and the warm-up time can be reduced.