[0001]    This application is based on Japanese Patent Application No. 2006-233320 filed on Aug. 30, 2006, the content of which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a bookbinding apparatus, and in particular, to a bookbinding apparatus that prepare booklets by bonding a plurality of sheets with adhesive. 
         [0003]    In the field of light printing, for example, image forming systems are being used widely that prepare booklets from printing to bookbinding in one process by coupling an image forming apparatus having the ability to form images at a high speed such as an electro-photographic image forming apparatus, and a bookbinding apparatus. 
         [0004]    Although such image forming systems have low printing speed and low bookbinding speed when compared with the conventional book manufacturing process in which the printing process and the bookbinding process are executed as separate processes, they have the advantage that it is possible to change the content of printing at any time and are on the whole high efficiency image forming systems, and are being used as POD (Print On Demand) systems. 
         [0005]    Since a POD system has the image forming apparatus and the bookbinding apparatus coupled to each other, and is not installed in a factory for printing and bookbinding but is very often installed either within an office or in the same building as the office, it has to be small in size, and all parts constituting the system are required to be small in size. 
         [0006]    Therefore, even as a bookbinding apparatus is used the type that prepares booklets by binding bundling sheets using adhesive bonding which is a relatively simple process. 
         [0007]    A reduced size bookbinding apparatus has been disclosed in Unexamined Japanese Patent Application Publication No. 2000-168265 that prepares a booklet by coating the adhesive by moving the coating roller relative to the longitudinal direction of the spine of the sheet bundle by moving the sheet bundle with respect to the coating roller. 
         [0008]    In Unexamined Japanese Patent Application Publication Nos. 2004-209746 and 2004-276457 are disclosed, in a coating apparatus suitable for small-sized bookbinding apparatus, an adhesive replenishing device that carries out replenishment of adhesive at an accurate rate in a simple manner. 
         [0009]    In Unexamined Japanese Patent Application Publication Nos. 2004-209746 and 2004-276457 is proposed a replenishing member that transports pellets of adhesive material along an inclined transport path, and by opening or closing a threshold member provided in the transport path, supplies a fixed quantity of pellets of about a few pellets during each replenishment. 
         [0010]    In a reduced size adhesive coating apparatus, since the level of the adhesive liquid in the adhesive reservoir varies widely because the volume of the adhesive reservoir that contains the liquid of the adhesive material is small, not only it is required to carry out replenishment of the adhesive accurately but also it is necessary to control the rate of replenishment according to the thickness of the sheet bundle, and a replenishment control that has accuracy and speed is required. 
         [0011]    When a replenishment mechanism is used that replenishes in units of a few pellets as in Unexamined Japanese Patent Application Publication Nos. 2004-209746 and 2004-276457, although the replenishment control is carried out by controlling the number of replenishments in units of a few pellets, there was the problem that the accuracy of the replenishment in this type of replenishment control is not sufficient, and also, that the speed of control of meeting speedily the changes in the quantity of adhesive and it was difficult to carry out uniform coating over a long period. 
         [0012]    In other words, when there is any disturbance in the unit of replenishment, because the inaccurate replenishment is carried out repeatedly, the replenishment error gets accumulated leading to the condition of excessive or insufficient quantity of adhesive in the adhesive reservoir. 
       SUMMARY OF THE INVENTION 
       [0013]    One aspect of the present invention is as follows. A bookbinding apparatus provided with a replenishing device having a pellet storing section that stores pellets of adhesive and a replenishing member that takes out pellets in a countable manner from the pellet storing section, and in addition, an adhesive reservoir that melts the pellets replenished from the replenishing member and stores the molten adhesive liquid, and a coating device having a coating member that coats the adhesive scooped up from the adhesive liquid. The bookbinding apparatus further has a replenishment sensor that detects the number of pellets replenished to the adhesive reservoir, and a controller that controls the replenishing member based on the output of the replenishment sensor. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a diagram showing an entire image forming system provided with a bookbinding apparatus according to a preferred embodiment of the present invention; 
           [0015]      FIG. 2  is a diagram showing a coating process; 
           [0016]      FIG. 3  is a diagram showing the configuration of the coating device  60 ; 
           [0017]      FIG. 4  is a cross-sectional view diagram of the replenishing device  61 ; 
           [0018]      FIG. 5  is a diagram showing important parts of the replenishing device  61  before the operations are started; 
           [0019]      FIG. 6  is a diagram showing important parts of the replenishing device  61  during replenishment; 
           [0020]      FIG. 7(   a ) and  FIG. 7(   b ) are diagrams showing a drive system in the replenishing device  61 ; 
           [0021]      FIG. 8  is a block diagram of the control system that carries out a replenishment control; and 
           [0022]      FIG. 9  is a flow chart of the replenishment control carried out by the controller CR. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Although the present invention is described here using a preferred embodiment shown in the figures, the present invention shall not be limited to the preferred embodiment. 
         [0024]      FIG. 1  is a diagram showing an entire image forming system provided with a bookbinding apparatus according to a preferred embodiment of the present invention. 
         [0025]    The image forming system has an image forming apparatus A and a bookbinding apparatus B. 
         [0026]    The image forming apparatus A is one that forms images on sheets using the electro-photography method, and has an image forming section A 1 , a document conveying device A 2 , and an image reading section A 3 . 
         [0027]    In the image forming section A 1  are arranged a charging unit  2 , an exposure unit  3 , a developing unit  4 , a transfer unit  5 A, a separation unit  5 B, and a cleaning unit  6  on the periphery of a drum shaped photoreceptor  1 , and using these electro-photographic process devices, a toner image is formed on the photoreceptor  1  and the image is formed on the sheet S 1  after charging, exposure, developing, and transfer are carried out. 
         [0028]    The sheets S 1  are stored in three sheet feeding trays  7 A, and one sheet at a time of the sheet S 1  is fed from these sheet feeding trays  7 A, and the toner image on the photoreceptor  1  is transferred onto the sheet S 1  by the transfer unit  5 A. 
         [0029]    The toner image transferred onto the sheet S 1  is fixed by passing through the fixing unit  8 . The fixed sheet S 1  either is discharged by the ejection roller  7 C or is conveyed to the re-feeding path  7 E. 
         [0030]    During face-down sheet discharge in single-sided printing, face-up sheet discharge in single-sided printing, or front surface image formation in double-sided image formation, the switching gate  7 D switches and guides the sheet S 1 . In other words, during face-up sheet discharge, the switching gate  7 D causes the sheet S 1  proceeds forward, and in face-down sheet discharge or in double-sided image formation, the switching gate  7 D guides the sheet S 1  downwards. 
         [0031]    During face-down sheet discharge, the sheet S 1 , after being guided downwards, is switched back and is conveyed in the upward direction, and is then discharged by the ejection roller  7 C. 
         [0032]    During double-sided image formation, the sheet S 1  is guided downwards, after being turned upside down by switching back, it passes through the sheet feeding path  7 E, fed to the transfer section in which is placed the transfer unit  5 A, and the image of the back surface is transferred onto it. 
         [0033]    The document conveying device A 2  conveys the document one sheet at a time to the reading position. The image reading section A 3  reads out the image of the document conveyed by the document conveying device A 2  or the image of the document placed on the document table  9 , and generates the image signals. The communication section A 4  carries out communication with a network device, receives the image forming command transmitted from the network, and generates the image signals. 
         [0034]    The bookbinding apparatus B is an apparatus that stacks a plurality of sheets that constitute a bundle and that are fed from the image forming apparatus A, and configures a bundle to be formed into a book, joins a cover sheet to that the sheet bundle, and prepares a book. In the following explanations, the sheets constituting sheets are called a sheet S 1 , and the cover sheet is called a cover S 2 , and the sheets constituting sheets to which a cover sheet has been joined is called a booklet S 3 . 
         [0035]    The bookbinding apparatus B has a conveyance section  10  that conveys the sheets S 1  discharged from the image forming apparatus A either to an ejection tray  20  or to a sheet reverse section  40 , an ejection tray  20 , a sheet reverse section  40 , a stacking section  50  that stacks the sheets S 1  sent one sheet at a time or several sheets at a time, a coating device  60 , a cover sheet storing section  80  that stores the cover sheets S 2 , a cover sheet supporting section  90  that supports the cover sheet S 2 , and a booklet ejection section  100 . 
         [0036]    The sheet S 1  discharged from the image forming apparatus A either is discharged to the ejection tray  20  via the ejection path  12  or is conveyed to the sheet reverse section  40  by the switching gate  11  provided in the conveyance section  10 . If the mode of operation is not the bookbinding mode, the sheets S 1  are discharged to the ejection tray  20 . 
         [0037]    In the bookbinding mode, the sheets S 1  are conveyed to the sheet reverse section  40  via the conveying path  13 , and, after being switched back in the sheet reverse section  40 , they are conveyed to the stacking section  50 . In the stacking section  50 , the sheets S 1  are stacked until the number of sheets becomes equal to a set number, the stacking section  50  is rotated when the number of sheets stacked becomes equal to the set number, and the bundle of sheets S 1  is held in an almost vertical condition. 
         [0038]    Adhesive is coated by the coating device  60  on the bottom surface of the bundle of sheets S 1  held in the vertical condition by the stacking section  50 . 
         [0039]    A cover S 2  is contacted with and adhered to the bundle of sheets S 1  on which adhesive has been coated. 
         [0040]    The booklet S 3  prepared by adhering the cover sheet S 2  to the bundle of sheets S 1  is discharged to the booking ejection section  100 . 
         [0041]      FIG. 2  is a diagram showing the coating process. 
         [0042]    The coating device  60  is placed below the sheet bundle SS of the sheets S 1 , and during its forward movement driven by the motor MT 2  indicated by the arrow W 2 , the coating roller  602  coats the adhesive AD on the spine SA of the sheet bundle SS, and during the reverse movement indicated by the arrow W 3 , the coating roller coats the adhesive AD on the spine SA. 
         [0043]    The home position of the coating device  60  is the left end position in  FIG. 2 , which is located at the deep side of the bookbinding apparatus shown in  FIG. 1 , and at this home position, pellets PT of the adhesive are replenished from the replenishment device  61 . The coating roller  602  is rotated in the direction indicated by the arrow W 1  due to the drive of the motor MT 1  during the forward and reverse movements thereby scooping up the adhesive from the adhesive reservoir  601  and coats it on the spine SA of the sheet bundle SS. 
         [0044]      FIG. 3  is a diagram showing the configuration of the coating device  60 . 
         [0045]    The coating device  60  has an adhesive reservoir  601  that stores the adhesive AD, a coating roller  602 , two regulating members  603  and  604 , a heater  605 , and an adhesive quantity sensor  606 . 
         [0046]    Although the pellets inside the adhesive reservoir  601  are heated and melted by the heater  605  thereby forming the coating liquid of the adhesive AD, the quantity of the adhesive AD is detected by the adhesive quantity sensor  606  composed of a temperature sensor, and the liquid surface is maintained constant. The part  603  is a regulating member having the shape of a rod with an almost circular cross-section, and the regulating member  604  is supported by a supporting member  607  having the shape of a plate, and limits the thickness of the layer of adhesive above the coating roller  602  using its bottom edge  604 B, and restricts the thickness of the adhesive layer on the spine SA of the sheet bundle SS using its top edge  604 A. 
         [0047]    The adhesive reservoir  601  is set by rotating from the standby state indicated by dotted lines to the coating state indicated by continuous lines around the shaft  601 A. 
         [0048]    The replenishment device  61  is explained here referring to  FIG. 4  to  FIG. 7 .  FIG. 4  is a cross-sectional view diagram of the replenishing device  61 ,  FIG. 5  shows the important parts of the replenishing device  61  before the operations are started, and  FIG. 6  shows the important parts of the replenishing device  61  during replenishment.  FIGS. 7(   a ) and  7 ( b ) show the drive system in the replenishing device  61 . 
         [0049]    The replenishment device  61  is composed of a hopper  62  as the pellet storing section that stores the pellets PT of the adhesive and the replenishing pipe  63  through which the pellets PT drop, and the frame  62 A constituting the hopper  62  supports the different parts described below. 
         [0050]    The replenishing device  61  is incorporated into the bookbinding apparatus B in the condition shown in  FIG. 4 , that is, in the condition in which the hopper  62  and the replenishing pipe  63  are inclined downward towards the left, and the pellets PT drop along the bottom surface of the frame  62 A and the bottom surface of the replenishing pipe  63 , and are supplied to the coating device  60 . 
         [0051]    The belt  663  that conveys the pellets PT is entrained about the rollers  664 ,  666 ,  667 , and  673  in the lower part of the hopper  62 . The roller  666  is the drive roller and rotates counterclockwise by being driven by the motor MT 3  which is a constituent part of the replenishing member. 
         [0052]    The belt  663  which is a constituent part of the replenishing member has concave-and-convex portions formed on its outer peripheral surface as is shown in the enlarge view diagram of  4 A, and because of this concave-and-convex surface, not only the pellets are conveyed definitely, but also the area of contact with the pellets PT is made small, thereby preventing adhesion between the pellets PT and the belt  663 . Because four pressure rollers  670  press the belt  663  against the frame  62 A using the force of springs, the spacing between the frame  62 A and the belt  663  is restricted so that it does not become larger than a prescribed limiting value, and because of this, the amount of conveying of the pellets PT by the belt  663  is controlled to be almost constant. 
         [0053]    The rollers  664  and  666  are supported by the supporting plate  662  that can swing about the rotating shaft  666 A of the roller  666 , and the supporting plate  662  is pulled clockwise by a pulling type spring  665 . Because of this, a constant tension force is applied to the belt  663  by the roller  664  pulled by the spring  665 . 
         [0054]    The rollers  667  and  669  are supported by the supporting plate  671  that can swing about the rotating shaft of the roller  667 . 
         [0055]    The replenishing device  61  in the stopped state before starting operations is as shown in  FIG. 5 , and in this state, the roller  669  has narrowed the pellet discharge outlet, and the pellets PT stay in the hopper  62  being blocked by the belt  663  supported by the roller  669  as shown in  FIG. 5 . 
         [0056]    When the replenishing device  61  starts operating, the roller  669  moves to the left as shown in  FIG. 6 , the belt  663  recedes, thereby making wide the pellet discharge outlet of the hopper  62 . Because of this, the pellets PT drop up to the discharge outlet, and the pellets PT that have dropped along the bottom surface of the frame  62 A due to the conveying action of the belt  663 . 
         [0057]    During the period when the replenishing device is carrying out replenishing operation, the roller  669  reciprocates between the position shown in  FIG. 5  and the position shown in  FIG. 6 , and because of this reciprocating operation, the pellets PT drop in small quantities at a controlled rate and are supplied to the coating device  60 . 
         [0058]    The roller  669  is an opening forming member that forms the narrow opening that blocks the discharge of the pellets PT and the wide opening that discharges the pellets PT due to the reciprocating movement. The drive mechanism that makes the roller  669  carry out reciprocating movement is explained using  FIG. 7(   a ) and  FIG. 7(   b ). 
         [0059]    A support plate  675  that rotates integrally with the roller  666  has been fixed to the shaft  666 A of the roller  666 , and a link  676  has been supported in a rotatable manner to the pin  677  provided at one end of the supporting plate  675 . 
         [0060]    The shaft  669 A of the roller  669  engages with and enters the long hole  676 A provided in the link  676 . 
         [0061]    The shaft  669 A of the roller  669  is pulled to the right in  FIGS. 7(   a ) and  7 ( b ) by a pulling type spring  668 . Therefore, the roller  669  is maintained at the prescribed position by the tension force of the belt  663  and the force of the spring  668 . 
         [0062]    Although the supporting plate  675  rotates due to the rotation of the roller  666 , because of the rotation of the supporting plate  675 , the right end position of the link  676  moves in the left and right directions in  FIGS. 7(   a ) and  7 ( b ), and because of this movement, the position of the roller  669  moves in the left and right directions, and hence the pellet discharge outlet of the hopper  62  contracts and expands as is shown in the state in  FIG. 5  and the state in  FIG. 6 . 
         [0063]    This contraction and expansion are repeated during the replenishment operation, and the pellets PT are supplied to the coating device  60  in small quantities at a controlled rate. 
         [0064]    Returning to  FIG. 4 , FS is a replenishment sensor that detects the pellets PT falling from the hopper  62 , and is composed of a light emitting device FS 1  and a light receiving device FS 2 . The number of pellets PT supplied to the coating device  60  is detected by the replenishment sensor FS. The count of the number of pellets PT by the replenishment sensor FS is proportional to the number of pellets PT replenished. 
         [0065]      FIG. 8  is a block diagram of the control system that carries out replenishment control, and  FIG. 9  is a flow chart of the replenishment control carried out by the controller CR. 
         [0066]    In STEP  1  in  FIG. 9 , the output of the adhesive quantity sensor  606  which is at the home position is monitored, and, based on the liquid surface reduction detection signal of the adhesive quantity sensor  606 , in STEP  2 , the motor MT 3  is started, and the replenishment of pellets is carried out. 
         [0067]    In STEP  3 , the count value of the replenishment sensor SF is monitored, and when the count value reaches a prescribed value, in STEP  4 , the motor MT 3  is stopped thereby ending the replenishment. 
         [0068]    In STEP  5 , the end of the job is monitored, and the operation of replenishment is ended when the job is completed, and the operation is returned to STEP  1  if the job has not ended. 
         [0069]    In the control, although one replenishment operation is from STEP  1  to STEP  5 , the prescribed value determining the quantity of replenishment in one replenishment operation is changed according to the thickness of the booklet, and the prescribed value is set to a large value when the thickness of the booklet is more. 
         [0070]    The thickness of the booklet is obtained from the information of the number of sheets constituting the booklet as set in the operation section of the image forming apparatus A, or, after detecting the thickness of the booklet in the stacking section  50  of  FIG. 1 , it is obtained from the detected information. 
         [0071]    In this manner, by carrying out replenishment control based on the result of detection by the replenishment sensor, during the bookbinding of a thick booklet, when the amount of consumption of the adhesive is large, the pellets of adhesive are replenished accurately according to the amount of consumption. 
         [0072]    In the present invention, since the quantity of replenishment of adhesive is detected and the replenishment control is carried out based on the result of detection, not only the quantity of adhesive in the adhesive reservoir is controlled accurately, but also, a control is carried out that corresponds speedily to the changes in the quantity of adhesive in the adhesive reservoir, and hence booklets are prepared with a stable quality.
A bookbinding apparatus includes: a replenishing device having a pellet storing section that stores pellets of adhesive and a replenishing member that takes out the pellets in a countable manner from the pellet storing section; an adhesive reservoir that melts the pellets replenished from the replenishing member and stores the molten adhesive liquid; a coating device having a coating member that coats the adhesive scooped up from the adhesive liquid; a replenishment sensor that detects the number of pellets replenished to the adhesive reservoir; and a controller that controls the replenishing member based on an output of the replenishment sensor.