Abstract:
A bookbinding apparatus comprising: a supplier which supplies solid adhesive to an adhesive tank; a melting section which melts the solid adhesive supplied to the adhesive tank; a coating member which coats the adhesive melted in the adhesive tank to an end face of a booklet; and a separating section which separates between a place in which the solid adhesive is supplied by the supplier and the coating member in the adhesive tank.

Description:
[0001]    This application is based on Japanese Patent Application No. 2006-301325 filed on Nov. 7, 2006, which is incorporated hereinto by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a bookbinding apparatus and bookbinding system for forming a booklet by coating adhesive on the edge (spine) of a plurality of stacked sheets, particularly to a bookbinding apparatus and bookbinding system wherein adhesive is coated for each booklet. 
         [0003]    There is a conventionally known bookbinding apparatus wherein adhesive is coated on each booklet and sheets are formed in a bundle, and this apparatus is used in a bookbinding system wherein all operations from image forming to bookbinding are performed in an integrated manner. In such a bookbinding apparatus, a hot melt adhesive is used as an adhesive, and adhesive pellets (solid glue) are supplied little by little in response to the amount consumed in coating, whereby bookbinding operation is performed on a continuous basis. In Unexamined Japanese Patent Application Publication No. 2004-209746, disclosed a supply apparatus wherein adhesive is coated on the sheet bundle by the traveling of a coating roller along the spine of a sheet bundle, and a predetermined amount of adhesive pellets are supplied little by little in units of several pellets into the melt adhesive tank wherein the coating roller is immersed. 
         [0004]    In the Unexamined Japanese Patent Application Publication No. 2004-209746, when the amount of adhesive in the adhesive tank has been reduced, pellets are supplied in predetermined amount, whereby the liquid level of the adhesive is kept constant. 
         [0005]    However, the bookbinding apparatus of the Unexamined Japanese Patent Application Publication No. 2004-209746 is designed in such a way that the solid glue is directly put into the melt glue portion wherein a coating roller is immersed. Thus, the half-melt solid glue is dipped up by the coating roller, and reaches the glue applied portion wherein the spine portion of the booklet conveyed comes in contact with the coating roller, with the result that a bookbinding failure occurs. 
         [0006]    Further, there is an attempt having been made so that the solid glue conveyance distance from the position for supplying solid glue into the melting tank, to the coating roller is set to a long distance so that the solid glue having been melted sufficiently inside the melting tank is supplied to the coating roller. This attempt, however, increases the size of the melting tank and the volume of evaporation of the melted glue inside the melting tank. This problem also leads to an increase in the melting warm-up time of the solid glue at the start of bookbinding. 
       SUMMARY OF THE INVENTION 
       [0007]    One aspect of the present invention is as follows. 
         [0008]    A bookbinding apparatus including: a supplier for supplying solid adhesive to an adhesive tank; a melting section for melting the solid adhesive supplied to the aforementioned adhesive tank; a coating member for applying the adhesive melted in the aforementioned adhesive tank to the end face of the booklet; and a separating section for separating between the place supplied with the solid adhesive by the supplier and the coating member in the aforementioned adhesive tank. 
         [0009]    Another aspect of the present invention is as follows. 
         [0010]    A bookbinding system including an image forming apparatus for forming an image on a sheet; and the bookbinding apparatus described above that receiving the sheet from the aforementioned image forming apparatus to perform the process of gluing and bookbinding. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a drawing representing the overall view of the bookbinding system constituted of a bookbinding apparatus in relation to an embodiment of the present invention; 
           [0012]      FIG. 2  is a drawing representing the process of applying an adhesive; 
           [0013]      FIG. 3  is a drawing showing the structure of a coating section; 
           [0014]      FIG. 4(   a ) is a side elevation view of the coating section and  FIG. 4(   b ) is an elevation view in cross section taken along arrow line  4 ( b )- 4 ( b ) in  FIG. 4(   a ) representing the coating section; 
           [0015]      FIGS. 5(   a )- 5 ( c ) are the side view, front view and perspective view representing the separating section, respectively; 
           [0016]      FIGS. 6(   a )- 6 ( b ) are the side elevation view in cross section as another embodiment of the coating section and a front view of the separating section, respectively; 
           [0017]      FIGS. 7(   a )- 7 ( c ) are the side view, front view and perspective view representing another embodiment of the separating section, respectively; 
           [0018]      FIGS. 8(   a )- 8 ( b ) are the side view representing still another embodiment of the separating section, and the front view representing the separating section, respectively; 
           [0019]      FIG. 9  is a diagram representing the percentage of the supply for proper bonding with reference to the number of sheets constituting a sheet bundle; 
           [0020]      FIG. 10  is a block diagram of the control system for controlling adhesive supply; and 
           [0021]      FIG. 11  is a flow chart of coating control. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    The following describes the present invention with reference to the embodiment of the present invention without being restricted thereto. 
         [0023]      FIG. 1  is a drawing representing the overall view of the bookbinding system constituted of a bookbinding apparatus in relation to an embodiment of the present invention. 
         [0024]    The bookbinding system includes an image forming apparatus A and bookbinding apparatus B. 
         [0025]    The image forming apparatus A forms an image on a paper using electrophotographic process, and includes an image forming section A 1 , document feeder A 2  and image reading section A 3 . 
         [0026]    In the image forming section A 1 , a charging unit  2 , exposing unit  3 , developing unit  4 , transfer unit  5 A, separation unit  5 B and cleaning unit  6  are arranged around a drum type photoreceptor  1 . The processes of charging, exposure, development and transfer are carried out by these electrophotographic processing units, whereby a toner image is formed on the photoreceptor  1 , and an image is formed on the sheet S 1 . 
         [0027]    Sheets S 1  are stored in three sheet feed trays  7 A, and the sheets S 1  are fed one by one from the sheet feed tray  7 A. The toner image on the photoreceptor  1  is transferred onto the sheet S 1  by the transfer unit  5 A. 
         [0028]    The toner image transferred onto the sheet S 1  is fixed by a fixing unit  8 . The fixed sheet S 1  is ejected from an ejection roller  7 C or is conveyed to the re-feeding path  7 E. 
         [0029]    In the face-down sheet ejection of the one-sided printing mode, in the one-sided printing of the face-up sheet ejection mode or in the front surface image formation of the two-sided image formation mode, the sheets S 1  are switched and guided by the switching gate  7 D. To be more specific, the switching gate  7 D feeds the sheet S 1  straight in the face-up sheet ejection, and guides the sheet S 1  downward in the face-down sheet ejection and two-sided image formation. 
         [0030]    In the face-down sheet ejection, after sheets S 1  have been guided downward, they are switched back, are conveyed upward, and are ejected by the ejection roller  7 C. 
         [0031]    In the two-sided image formation, the sheets S 1  are fed backward and the front and rear are reversed switchback. After that, the sheets S 1  are fed along the re-feeding path  7 E, and are re-fed to the transfer section equipped with a transfer unit  5 A, whereby the rear image is transferred. 
         [0032]    The document feeder A 2  feeds documents one by one to the reading position. The image reading section A 3  reads the image of the documents conveyed by the document feeder A 2  or the image of the documents placed on a document platen  9 , whereby an image signal is generated. 
         [0033]    The bookbinding apparatus B bundles a plurality of the constituent sheets fed from the image forming apparatus A and forms them into a bundle of the constituent sheets. The bookbinding apparatus B further bonds this bundle with cover sheet paper, whereby a book is created. In the following description, this constituent paper is referred to as a sheet S 1 , and the cover sheet paper is called a cover sheet S 2 . The constituent sheets bonded with the cover sheet paper will be referred to as a booklet S 3 . 
         [0034]    The bookbinding apparatus B includes: a conveying section  10  which conveys the sheets S 1  having been ejected from the image forming apparatus A, to the sheet ejection tray  20  or sheet reversing section  40 ; a sheet ejection tray  20 ; a sheet reversing section  40 ; a stacking section  50  for stacking the sheets S 1  having been fed one by one or a few sheets by a few sheets; a coating section  60 ; a cover sheet storage section  80  for storing the cover sheet S 2 ; a cover sheet support section  90  for supporting the cover sheet; and a booklet ejection section  100 . 
         [0035]    The sheets S 1  ejected from the image forming apparatus A are ejected to the sheet ejection tray  20  through the ejection path  12  by the switching gate  11  provided on the conveying section  10 , or are conveyed to the sheet reversing section  40 . Except in the bookbinding processing mode, the sheets S 1  are ejected to the sheet ejection tray  20 . 
         [0036]    In the bookbinding mode, the sheets S 1  are conveyed to the sheet reversing section  40  through the conveyance path  13 , and are conveyed to the stacking section  50  after having been switched backed by the sheet reversing section  40 . A predetermined number of sheets S 1  are stacked in the stacking section  50 . When a set number of sheets have been stacked, the stacking section  50  rotates to hold the bundle of the sheets S 1  almost in the upright position. 
         [0037]    The lower surface of the bundle of sheets S 1  held by the stacking section  50  in the upright position is coated with adhesive by the coating section  60 . 
         [0038]    The cover sheet S 2  is brought in contact with the bundle of the sheets S 1  coated with adhesives, and is bonded therewith. 
         [0039]    The booklet S 3  created by the cover sheet S 2  being bonded with the bundle of the sheets S 1  is ejected to a booklet ejection section  100 . 
         [0040]      FIG. 2  is a drawing representing the process of applying an adhesive. 
         [0041]    The coating section  60  is located below the sheet bundle SS. Melted adhesive AD is coated on the spine SA of the booklet SS as a bundle of the sheets S 1  by the coating roller (coating member)  602  as a coating member at the time of outward movement in the direction W 2  by the motor MT 1 . Adhesive AD is coated on the spine SA by the coating roller  602  at the time of homeward movement in the direction W 3 . 
         [0042]    The home position of the coating section  60  is found on the left end in  FIG. 2 , and is on the further rear side as viewed from the front of the bookbinding apparatus B of  FIG. 1 . In the home position, pellets (solid adhesive) PT of the adhesive are supplied from the supplier  61 . The coating roller  602  is rotated by the motor MT 2  in the direction W 1  at the time of outward and homeward movements. Adhesive is drawn up from the adhesive tank (melting section)  601 , and is applied to the spine SA of the sheet bundle SS. 
         [0043]      FIG. 3  is a drawing showing the structure of the coating section  60 . 
         [0044]    The coating section  60  includes an adhesive tank  601  for storing the adhesive AD, coating roller  602 , regulating members  603  and  604 , heater  605 , adhesive amount sensor  606  and separating section  607 . 
         [0045]    The pellets PT in the adhesive tank  601  are heated and melted by the heater  605 , whereby the coating solution of the adhesive AD is formed. The amount of adhesive AD is detected by the adhesive amount sensor  606  made up of a temperature sensor, and pellets PT are supplied so that the liquid is kept at a predetermined level. The regulating member  603  is a rod-like member having an almost circular cross section. The regulating member  604  is supported by the plate-formed support member  604 C. The layer thickness of the adhesive coated on the coating roller  602  is regulated by the bottom edge  604 B, and the layer thickness of the adhesive on the spine SA of the sheet bundle SS is regulated by the top edge  604 A. 
         [0046]    The adhesive tank  601  is set by rotating about the axis  608  from the standby status indicated by the dotted line to the coated status indicated by the solid line. 
         [0047]    The adhesive amount sensor  606  has the temperature detection element composed of a thermistor. When the adhesive amount sensor  606  is immersed in the solution of the adhesive AD, the detected temperature is increased. When the liquid level is reduced so that the adhesive amount sensor  606  is separated from the liquid surface, the detected temperature is reduced. That the adhesive amount has been reduced below a predetermined value is recognized by the detection of this temperature reduction. When adhesive amount reduction detection signal has been outputted, the adhesive is supplied. The reference numeral  607  denotes a separating section to be described later. 
         [0048]      FIG. 4  ( a ) is a side elevation view in cross section showing the coating section  60  when the coating roller as a coating roller is rotating.  FIG. 4  ( b ) is a cross section taken along arrow line  4 ( b )- 4 ( b ) of the coating section  60 . The regulating members  603  and  604 , heater  605  and adhesive amount sensor  606  are not illustrated. 
         [0049]    A separating section  607  is disposed below the supplier  61  of  FIG. 2  inside the adhesive tank  601  and coating roller  602 . An adhesive tank  601  is partitioned into a supply tank  601 A and melting tank section  601 B, using this separating section  607  as a boundary therebetween. To be more specific, the supply tank  601 A for supplying pellets PT is located on the illustrated left side of the separating section  607 , and the melting tank section  601 B including the coating roller  602  and adhesive amount sensor  606  is located on the right side of the separating section  607 . 
         [0050]      FIG. 4  ( a ) shows that the coating roller  602  is currently rotating. A greater amount of the adhesive AD in the adhesive tank  601  is supplied to the right of the coating roller  602  by the rotation of the coating roller  602 . Accordingly, the liquid levels of adhesive AD in the adhesive tank  601  are different on the right and left separated by the coating roller  602 . However, if the rotation of the coating roller  602  has stopped, the liquid adhesive AD levels are the same on the right and left. 
         [0051]      FIGS. 5(   a )- 5 ( c ) show the separating section  607 .  FIG. 5(   a ) is the side view of the separating section  607 ,  FIG. 5(   b ) is the front view and  FIG. 5(   c ) is the perspective view, respectively. 
         [0052]    The separating section  607  includes a pair of upright side plates  607 A on the right and left, a fence section  607 B for bridging the bottom portion of the side plate  607 A, and an installation surface  607 C formed on each top of a pair of the side plates  607 A on the right and left. These components are molded into one integral body. The separating section  607  is processed by pressing through the use of a thin plate such as a stainless steel and phosphor bronze plate. 
         [0053]    The installation surface  607 C is fixed on the top surface of the adhesive tank  601  by screws, as shown in  FIGS. 4(   a )- 4 ( b ). The bottom section  607 D of the side plate  607 A of the separating section  607  comes in contact with the bottom section inside the adhesive tank  601 , as shown in  FIGS. 4(   a )- 4 ( b ). 
         [0054]    The fence section  607 B is provided with a plurality of tunnel-shaped passages  607 J. The passage  607 J allows the melted adhesive AD to pass by, and blocks the traveling of the unmelted pellets PT of large diameter coming from the supplier  61 . 
         [0055]    To be more specific, the passage  607 J of the fence section  607 B prevents the half-melted pellets PT of large diameter from being conveyed deposited on the coating roller  602 , and from being bonded on the spine section of the sheet bundle SS, which might result in a gluing failure. The passage  607 J allows the unmelted pellets PT of reduced diameter to pass by. The pellets PT of reduced diameter go through the passage  607 J and are melted by the melting tank section  601 B. 
         [0056]    The half-melted pellets of smaller diameter and melted adhesive AD passing through the passage  607 J are fed to the melting tank section  601 B equipped with a coating roller  602 , wherein they are melted and are coated on the outer peripheral surface of the rotating coating roller  602 . 
         [0057]    A plurality of protrusions  607 G are formed on the upper portion of the fence section  607 B. The front end of the protrusion  607 G is placed close to the outer peripheral surface of the coating roller  602  maintaining a predetermined interval. The protrusions  607 G are provided to ensure at the time of gluing on the sheet bundle SS that, when small blocks of unmelted pellets PT has been fed inside the adhesive AD and they have been deposited on the surface of the coating roller  602 , they are separated from the surface of the coating roller  602  and are returned to the supply tank section  601 A. The protrusions  607 G are not provided along the entire length of the protrusion  607 G. This is because the required minimum effect can be obtained if they are provided in the area of the maximum thickness of the sheet bundle that can be glued. 
         [0058]    The separating section  607  is arranged in such a way that the fence section  607 B is located at the same position as the liquid adhesive AD level in the adhesive tank  601  when the coating roller  602  is rotating. This arrangement effectively eliminates the possibility that the solid pellets PT immediately after being supplied would be fed to the side of the coating roller  602 . This is estimated to be because the solid pellets PT immediately after supply tends to float close to the adhesive AD liquid surface. 
         [0059]      FIG. 6(   a ) is the side elevation view in cross section as another embodiment of the coating section  60 .  FIG. 6(   b ) is a front view of the separating section  607 . These drawings use the same reference numerals of  FIGS. 5(   a )- 5 ( c ) for the portions having the same functions as those of  FIGS. 5(   a )- 5 ( c ). Only the differences from  FIGS. 5(   a )- 5 ( c ) will be described below. 
         [0060]    The fence section  607 B of the separating section  607  is provided with four elongated circular through-holes  607 F long in the horizontal direction. The upper portion of the elongated circular hole  607 F is provided with two rectangular through-holes  607 H. 
         [0061]      FIGS. 7(   a )- 7 ( c ) show another embodiment of the separating section  607 .  FIG. 7(   a ) is a side view of the separating section  607 ,  FIG. 7(   b ) is a front view, and  FIG. 7(   c ) is a perspective view, respectively. These drawings uses the same reference numerals of  FIGS. 5(   a )- 5 ( c ) for the portions having the same functions as those of  FIGS. 5(   a )- 5 ( c ). Only the differences from  FIGS. 5(   a )- 5 ( c ) will be described below. 
         [0062]    The fence section  607 B is provided with a plurality of elongated circular through-holes  607 F. The through-holes  607 F allow the melted adhesive AD to pass by, and block the traveling of the unmelted pellets PT coming from the supplier  61 . To be more specific, the through-holes  607 F of the fence section  607 B eliminate that possibility that the half-melted pellets PT is conveyed deposited on the coating roller  602 , and is adhered on the spine section of the sheet bundle SS, which might result in a gluing failure. 
         [0063]    The half-melted pellets of smaller diameter and melted adhesive AD passing through the through-hole  607 F are fed to the melting tank section  601 B equipped with a coating roller  602 , wherein they are further melted and are coated on the outer peripheral surface of the rotating coating roller  602 . 
         [0064]    A plurality of protrusions  607 G are formed on the upper portion of the fence section  607 B. The front end of the protrusion  607 G is placed close to the outer peripheral surface of the coating roller  602  maintaining a predetermined interval. 
         [0065]      FIG. 8(   a ) is a side view representing still another embodiment of the separating section  607 .  FIG. 8(   b ) is a front view representing the separating section  607 . These drawings uses the same reference numerals of  FIGS. 6(   a )- 6 ( b ) for the portions having the same functions as those of  FIGS. 6(   a )- 6 ( b ). Only the differences from  FIGS. 6(   a )- 6 ( b ) will be described below. 
         [0066]    The fence section  607 B of the separating section  607  is provided with an elongated circular through-hole  607 F long in the horizontal direction, and upper portion of the through-hole  607 F is equipped with two rectangular through-holes  607 H. 
         [0067]      FIG. 9  is a diagram representing the percentage of the supply for proper bonding with reference to the number of sheets constituting a sheet bundle. 
         [0068]    As described above, the reduction in the adhesive AD liquid level is detected and adhesive pellets PT are supplied in response to the detection signal. The following describes the percentage of the pellets PT to be supplied, with reference to  FIG. 9 . 
         [0069]    In  FIG. 9 , the horizontal axis indicates the number P of sheets S 1  constituting the sheet bundle SS, and the vertical axis indicates the number C of pellets PT to be supplied, that have been counted by a supply sensor FS. This is the result of the coating test having been conducted using the coating section  60  of  FIG. 3 . 
         [0070]    In  FIG. 9 , the horizontal axis represents the number of sheets P in booklet S 3 . Theoretically, it indicates the amount of the adhesive AD consumed by coating. The amount of the adhesive AD consumed corresponds to the thickness of the sheet bundle SS mainly determined by the number P of the sheets S 1  and the thickness of one sheet S 1 , and paper size. Further, the amount of consumption also depends on the type of paper such as coated paper or non-coated paper. 
         [0071]    The straight line L 1  is expressed by the following equation. 
         [0000]        N =10+0.019  Equation 1 
         [0072]    In this case, the count of the supply sensor FS is not always equal to the number of the pellets PT to be supplied. In the test example, one count of the supply sensor FS corresponded to 2.5 pellets PT. 
         [0073]    In the actual control, as shown in the stair-shaped line L 2 , the number of the pellets PT wherein the figures below decimal are omitted is used for control as representing the proper amount of supply. The adhesive amount sensor adhesive amount sensor  606  (shown in  FIG. 3 ) receives the signal having detected the reduction in liquid level, and supply of the pellets PT is started. The count corresponding to the amount of supply corresponding to the number of sheets is given by Equation 1, and the proper value illustrated in  FIG. 9  is reached. Then the controller terminates the supply. 
         [0074]    The aforementioned control ensures the liquid adhesive surface to be kept at an almost constant level at all times, whereby uniform coating is performed. 
         [0075]    Referring to  FIGS. 10 and 11 , the following describes the adhesive supply control. 
         [0076]      FIG. 10  is a block diagram of the control system for controlling adhesive supply, and  FIG. 11  is a flow chart of coating control. 
         [0077]    The controller CR provides the pellet PT supply control, wherein information on the sheet bundle SS is obtained from the main body control section MC as the control section of the image forming apparatus A, and the driving motor MT 3  constituting a supplier for supplying pellets PT is initiated, in response to the signal having detected the liquid level of the adhesive amount sensor  606  for detecting the liquid level in the adhesive tank, whereby pellets PT are supplied. When the supply amount obtained from the supply amount detection signal of the supply sensor FS has reached a proper value, the motor MT 3  is terminated under this control. 
         [0078]    In STEP  1 , information on the sheet bundle SS to be coated with adhesive AD is inputted. The information on the sheet bundle SS includes the number of sheets constituting the booklet S 3 , the thickness of paper, the type of paper such as coated paper or non-coated paper, and the size of paper. 
         [0079]    In STEP  2 , the coating section  60  performs a back-and-forth motion, whereby adhesive is coated on the spine of the sheet bundle SS. 
         [0080]    In STEP  3 , a step is taken to detect the reduction in the adhesive liquid level subsequent to implementation of coating process in STEP  2 . If the reduction is not detected (N in STEP  3 ), the system terminates the procedure. If it has been detected (Y in STEP  3 ), the proper coating amount is calculated (STEP  4 ). 
         [0081]    The calculation in STEP  4  is performed, for example, according to the stair-shaped line L 2  of  FIG. 9  with reference to the Lookup Table stored in the memory section of the controller CR. 
         [0082]    In STEP  5 , pellet supply starts. 
         [0083]    In STEP  6 , the output of the supply sensor FS is monitored. When the count of the supply sensor FS has reached the proper value (Y in STEP  6 ), supply stops and the procedure terminates (STEP  7 ). 
         [0084]    When a predetermined number of booklets S 3  have been produced and the bookbinding job has completed (Y in STEP  8 ), the procedure terminates. If not, the system goes back to STEP  2  (N in STEP  8 ). 
         [0085]    In  FIGS. 10 and 11 , the controller CR inputs the information of the sheet bundle SS, and the pellet supply amount is determined based on the inputted information. However, the information on the sheet bundle SS includes the number of sheets P, and the thickness, type and size of the sheets. The controller CR calculates information required for calculation of the percentage of supply from such information. In addition to this automatic supply, the operator can directly set the percentage of supply. 
         [0086]    For example, it is also possible to make such arrangements that the percentage of supply is assigned with a several steps, and the operator selects and sets the proper percentage of supply according to the thickness of the sheet bundle SS and others. Thus, the setting of the operator is inputted into the controller CR as information on the sheet bundle SS. 
         [0087]    In the automatic supply control, the controller CR obtains information on the number of sheets, the thickness and size of the sheet and others from the image forming apparatus A and calculates the proper percentage of supply. It is also possible to arrange such a configuration that the stacking section  50  of the sheet bundle SS of  FIG. 1  is provided with a sheet thickness sensor for detecting the thickness of the sheet bundle SS, and the controller CR calculates the proper percentage of supply in response to the detection signal of the sheet thickness sensor. 
         [0088]    The present embodiment of the present invention provides a bookbinding apparatus and a bookbinding system wherein, in a downsized coating section, a separating section prevents the half-melt solid adhesive from being coated onto the end face (spine) of the booklet by the coating section, whereby a high-quality booklet with a high degree of bonding strength is created.