Abstract:
Bookbinding-unit adhesive application device that does not interrupt the unit to replenish adhesive when consecutively applying adhesive to sheet bundles, and can shorten the time the system is interrupted. An adhesive storage container ( 10 ) that stores adhesive; an applicator roller ( 30 ) rotatably disposed in the adhesive storage container ( 10 ); an adhesive supplier ( 55 ) that refills hot-melt adhesive to the adhesive storage container ( 10 ); heater ( 20 ) that melts the adhesive in the adhesive storage container ( 10 ); and refill volume controller ( 62 ) that controls the amount of refill adhesive of the adhesive supplier ( 55 ) are provided. The refill volume controller ( 62 ) is configured to set the adhesive refill volume based on information from adhesive detector ( 22   a ) disposed in the adhesive storage container ( 10 ); and remaining sheets determiner ( 63 ) that determines the number of sheets to coat for the sheet bundles to be coated with adhesive.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention, involving adhesive applicators associated with bookbinders and bookbinders employing adhesive applicators, relates to improvements in adhesive application mechanisms for applying hot-melt adhesive to the spine-portion endface of sheet bundles collated into block form. 
         [0003]    2. Description of the Related Art 
         [0004]    Generally, this kind of adhesive application device is widely known to collate into a bundle shape sheets conveyed from an image-forming apparatus or the like and hold that bundle at a predetermined adhesive application position. It is equipped with an adhesive container that applies adhesive to a bottom edge of the sheet bundle (the spine binding portion) and to coat an adhesive roller disposed in this container with adhesive for application. A method is also widely used to store hot-melt adhesive in the adhesive container and to melt it with heating means. 
         [0005]    For example, a device that has an adhesive container below the sheet bundle held in an upright posture and applies a predetermined amount of adhesive using an applicator roller while moving this container along the spine binding edge of the sheet bundle is proposed in Japanese Unexamined Pat. App. Pub. No. 2007-76118. In this publication, a refilling mechanism that supplies solid-form adhesive to the container and a device that is equipped with heating means to melt the solid-form adhesive charged into this container. 
         [0006]    It is necessary to refill the adhesive when the system is designed to store hot-melt adhesive in the container and to use heat to melt the adhesive for application. The container is configured to be large. To refill a large amount of adhesive at one time, there is the problem that it takes a long time to melt the charged adhesive. This problem causes the dropping of the adhesive temperature which can cause the adhesive in the container to harden or becoming semi-hardened (gel-form) when the machine is not being used or between applications of adhesive. 
         [0007]    Here, Pat. App. Pub. No. 2007-76118 proposes a comparatively small and compact container that stores the adhesive and a device that supplied the adhesive according to the status of adhesive consumption in the device. In this publication, a refilling mechanism has a sensor to detect the amount of adhesive in the container and supply a predetermined amount of solid-form adhesive to the container according to detection signals from this sensor. 
         [0008]    Conventionally, regardless of the volume of the adhesive container, this sensor detects that the adhesive in the container has been consumed below a predetermined level. The system is configured to charge a preset amount (fixed amount) of adhesive at the detection signals from this sensor. Normally, this sensor detects a state (near-empty) just prior to the adhesive in the container becoming empty. After the adhesive application in the finishing process is ended, adhesive is charged into the container for the next adhesive application process. 
         [0009]    As described above, a sensor (level sensor) is provided to detect the amount of adhesive in the adhesive container, and when refilling adhesive at a signal, conventionally, the sensor detects a near-empty state and after the detection, and the predetermined application operation (finishing operation) is ended, a predetermined amount of adhesive is charged into the container. 
         [0010]    In such a case, if the container is configured to be large, the amount of adhesive to refill is higher and melting requires more time. Also, if the container is configured to be compact, the melting time is shorter, but the adhesive must be refilled more frequently. 
         [0011]    Meanwhile, the amount of adhesive consumed greatly varies depending on the size and thickness of the sheet bundle to be coated with adhesive. For example, when the bookbinding device binds a maximum size of 100 sheets in the sheet bundle, the amount of adhesive consumed for 10 sheets 1/10 the total amount. Even if the number of copies to be coated with adhesive consecutively cannot be determined uniformly because there are times when there are 10 copies, or when there are as many as 100 copies. 
         [0012]    Conventionally, the refilling of adhesive to the container was set in the following way. First, the maximum and minimum levels of adhesive in the container were set when the unit is designed. Then, when a sensor that detects when the adhesive amount has reached the minimum level, the application operation is set to be completed when it detects a near-empty state. In other words, the adhesive amount when in a near-empty state is set to be able to apply adhesive at least one time when the sheet bundle is a maximum size, and the thickness is the maximum sheet bundle thickness. The system is set so that the refilling amount of adhesive to the container is the maximum level when the adhesive in the container is consumed to the minimum level so that the adhesive does not exceed the maximum level and overflow the container. 
         [0013]    In this way, the following problems were created with the conventional adhesive refilling method. When the near-empty sensor has detected that the adhesive is at a minimum level, the adhesive amount control means refills a predetermined amount of adhesive to the container and sets it to the maximum level of the container when the process to apply adhesive to the sheet bundle being coated part way is ended. For that reason, the system must wait until the adhesive reaches a predetermined temperature to continue applying adhesive to subsequent sheet bundles. However, even though the amount of adhesive remaining in the container is adequate if the subsequent sheet bundle is a low number of copies, for example one sheet bundle, the system is interrupted to refill the adhesive. 
         [0014]    If the maximum sheet bundle thickness for that unit is 100 sheets, and the system is set to be able to apply adhesive for 100 sheets after the near-empty state is detected, and the actual sheet bundle is 10 sheets, it is possible to continue applying adhesive to 10 sheet bundles with the amount of adhesive remaining in the container. In such a case, when the number of sheet bundles to be subsequently processed is less than 10 copies, even though it is possible to continue applying adhesive, the system is interrupted to refill the adhesive. 
         [0015]    Also, when the sensor detects a near-empty state, even if the subsequent number of sheet bundles is low, conventionally, a predetermined amount of adhesive is refilled to reach the maximum level. Therefore, even if the insufficient adhesive is enough for one sheet bundle, a predetermined amount of adhesive is refilled, so there is the problem of requiring a longer amount of waiting time to refill the adhesive (melting time when using hot-melt adhesive). 
         [0016]    This problem occurs frequently if the size of the container is smaller, and if the container is larger, the frequency of the problem is lower, but the time required to wait for the refilling of adhesive is longer. Even if the container is configured to be large or small, the conventional method to refill adhesive has the problem of an unnecessarily long wait for processing because adhesive is refilled until the maximum level regardless of the number of sheet bundles, the size and the bundle thickness when the sensor has detected a near-empty state. 
       BRIEF SUMMARY OF THE INVENTION 
       [0017]    The inventors came upon the idea of solving the aforementioned problems by refilling adhesive according to the amount consumed by subsequent sheet bundles. 
         [0018]    An object of the present invention is to provide an adhesive application device in a bookbinding unit that does not interrupt a device to refill adhesive when consecutively applying adhesive to sheet bundles with an applicator roller and the like, and can shorten the time the system is interrupted. 
         [0019]    Furthermore, the present invention provides a bookbinding device and image-forming system that improve the system operating rate by accurately setting the number of refills of adhesive and the refilling time with a simple structure. 
         [0020]    In a device configuration that disposes adhesive supply means for supply adhesive to the adhesive container and refill amount control means that controls the amount of refill adhesive, to overcome the aforementioned issues, the present invention is configured to set the amount of refill adhesive based on information from adhesive amount detection means with the refill amount control means in the container and remaining sheets determining means that determines the number of sheets in a sheet bundle to be coated with adhesive. The configuration will be explained in detail below. 
         [0021]    An adhesive application device that sequentially applies adhesive to a spine portion of continuously supplied sheet bundles has an adhesive storage container ( 10 ) that stores adhesive; an applicator roller ( 30 ) rotatably disposed in the adhesive storage container ( 10 ); an adhesive supply means ( 55 ) that refills hot-melt adhesive to the adhesive storage container ( 10 ); heating means ( 20 ) that melts the adhesive in the adhesive storage container ( 10 ); and refill amount control means ( 62 ) that controls the amount of refill adhesive of the adhesive supply means ( 55 ). The refill amount control means ( 62 ) is configured to set the amount of refill adhesive based on information from adhesive detection means ( 22   a ) disposed in the adhesive storage container ( 10 ); and remaining sheets determining means ( 63 ) that determines the number of sheets to coat of the sheet bundle to be coated with adhesive. 
         [0022]    The remaining sheets determining means ( 63 ) is configured to determine the number of completed applications of the sheet bundle coated with adhesive by the applicator roller ( 30 ) and the number of applications of the empty sheet bundle. 
         [0023]    The refill amount control means ( 62 ) has a scheduled consumption amount calculation means ( 64 ) that calculates the scheduled consumption amount of adhesive from the remaining number of applications of the sheet bundle from the remaining sheets determining means ( 63 ) and the amount of adhesive applied to one sheet bundle. 
         [0024]    The refill amount control means ( 62 ) has comparing means ( 65 ) that compare the preset refill amount and the scheduled consumption amount from the scheduled consumption amount calculation means ( 64 ). Also, when the scheduled consumption amount is detected to be lower than the set refill mount by the comparing means ( 65 ), the adhesive refilling amount is set based on this set consumption amount. 
         [0025]    The scheduled consumption amount calculation means ( 64 ) is configured to calculate the scheduled consumption amount of adhesive from the remaining number of applications of the sheet bundle and either from (1) the preset application amount to be applied to one sheet bundle, or (2) the application amount of adhesive to be applied to one sheet bundle calculated from information such as the size of the remaining sheet bundles, the number of sheets, the sheet bundle thickness and material and the like. 
         [0026]    The refill amount control means ( 62 ) has a plurality of set refill amounts that differ for the preset adhesive amount, and this refill amount control means ( 62 ) refills adhesive to the adhesive container ( 10 ) by selecting one of the set refill amounts based on information from the remaining sheets determining means ( 63 ). 
         [0027]    The bookbinding device according to the present invention is equipped with a sheet bundle conveyance path (hereinafter referred to as a bookbinding path  47 ) that sequentially conveys a collated and stacked sheet bundle; an adhesive application unit disposed in the bookbinding path  47  that applies adhesive to a spine portion of the sheet bundle; and total number of sheets processed recognition means that determines the total number of subsequent sheet bundles. The adhesive application unit is configured as described above. 
         [0028]    Stacking means (hereinafter referred to as a stacking tray  44 ) for collating and stacking sequentially conveyed sheets into a sheet bundle is disposed in the bookbinding path  47 ; the refill amount control means ( 62 ) charges adhesive to the adhesive container ( 10 ) based on a detection signal from the adhesive amount detection means ( 22   a ) and on information from the remaining sheets determining means ( 63 ) in the time that the later sheets are being stacked in the stacking means (stacking tray  44 ). 
         [0029]    The total number of sheets processed recognition means is configured to ascertain information using input information from input means that inputs the total number of sheet bundles to process or information transferred from another device. 
         [0030]    Sheet stacking means (hereinafter referred to as stacking tray  44 ) that collates sheets into sheet bundles is disposed upstream of the bookbinding path  47 . The heating means ( 20 ) is configured to melt the adhesive filled from the adhesive supply means ( 55 ) while the sheets are being stacked by the stacking tray  44 . 
         [0031]    The image-forming system according to the present invention is composed of an image-forming device that has image-forming means for sequentially forming images on sheets, and a bookbinding device that collates into sheet bundles sheets conveyed from the image-forming device, coats an edge of the sheet bundle with adhesive and then binds the sheet bundle to a cover sheet; the bookbinding device is configured as described above. 
         [0032]    The present invention has the following effects when adhesive is supplied to the adhesive storage container because it sets the adhesive refilling amount based on information from the adhesive amount detection means in the container and remaining sheets determining means that determines the remaining number of applications to the sheet bundle. 
         [0033]    First, it is possible to set the adhesive refilling amount to be low if the remaining number of sheets to be coated with adhesive is low, and to be high if the remaining number of sheets to be coated with adhesive is high, by setting the refilling amount based on the information of the remaining number of sheets, and the detection signals from the adhesive amount detection means. For this reason, it is particularly possible to shorten the time needed to refill the adhesive when the remaining number of applications is low. 
         [0034]    The present invention can set the refill amount based on the detection signals from the detection means of the adhesive in the container and information from the remaining number of applications of the sheet bundle, so it is possible to continue applying adhesive without refilling adhesive when it is possible to apply adhesive to the remaining sheet bundles with the adhesive remaining in the container. 
         [0035]    Furthermore, the present invention can refill adhesive to the minimum required by refilling the adhesive according to the scheduled consumption amount by calculating the consumption amount of adhesive from the next sheet bundle thickness (or information on the number of sheets), the sheet sizes, and materials and the like, based on remaining number of applications information. For that reason, it is possible to shorten the time required to refill the adhesive (the melting time for hot-melt adhesive) and not leave a large amount of adhesive in the container when machine operation is ended. Therefore, when changing the adhesive for the bookbinding specifications, it is easy to remove the residual adhesive. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0036]      FIGS. 1A to 1C  are explanatory views of an adhesive application device (unit) used in a bookbinding device according to the present invention;  FIG. 1A  is a perspective view of the external shape of the unit;  FIG. 1B  is a sectional view in an X-X direction;  FIG. 1C  is a sectional view in a Y-Y direction; 
           [0037]      FIGS. 2A and 2B  show an adhesive refilling mechanism in the adhesive application unit shown in  FIG. 1 ;  FIG. 2A  shows an overall configuration thereof;  FIG. 2B  shows a measuring mechanism to measure the adhesive refilling amount; 
           [0038]      FIG. 3  is an explanatory drawing of an application mechanism that applies adhesive to a sheet bundle with the adhesive application device of  FIG. 1 ; 
           [0039]      FIG. 4  is an overall explanatory view of an image-forming system installed with the adhesive application unit; 
           [0040]      FIG. 5  is an explanatory view showing in detail the bookbinding unit in the system shown in  FIG. 4 ; 
           [0041]      FIGS. 6A and 6B  are explanatory views of a bookbinding operation in the system shown in  FIG. 4 ;  6 A shows a state of adhesive being applied;  6 B shows a state where the sheet bundle coated with adhesive being joined to a cover sheet; 
           [0042]      FIGS. 7A and 7B  are explanatory views of the bookbinding operation in the system shown in  FIG. 4 ;  7 A shows an initial state of the sheet bundle and cover sheet being bound;  7 B shows a state where the cover sheet is being folded over and covering the sheet bundle; 
           [0043]      FIG. 8  is an explanatory drawing of a control flow showing the refilling operation of adhesive in the device shown in  FIG. 1 ; 
           [0044]      FIG. 9  is a detailed flowchart of adhesive refilling in the control flow of  FIG. 8 ;  FIG. 9A  is a first embodiment;  FIG. 9B  is a second embodiment; and 
           [0045]      FIG. 10  is a block diagram showing a configuration of control means in the system shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0046]    A preferred embodiment of the present invention will now be explained based on the drawings provided. An adhesive application unit B built-in to the bookbinding unit of the present invention will now be explained with reference to  FIGS. 1 to 3 .  FIG. 1  is an explanatory drawing showing a structure of the adhesive container that stores solid adhesive.  FIG. 1A  is a perspective view;  1 B is an X-X sectional view;  1 C is a Y-Y sectional view.  FIG. 4  is an overall view of bookbinding unit with a built-in adhesive application unit and an image-forming system.  FIG. 5  is a view of the essential portion of the bookbinding unit shown in  FIG. 4 . 
       Adhesive Application Unit Configuration 
       [0047]    The adhesive application unit B shown in  FIG. 1A  is composed of an adhesive container  10  (hereinafter referred to as “container”) that stores adhesive; an applicator roller  30  that applies liquefied adhesive to a sheet bundle; and heating means  20  mounted inside the container to melt adhesive. The adhesive container  10  is partitioned into a solid adhesive charging compartment  10   b  (hereinafter referred to as the charging compartment) and a liquefied adhesive tub  10   a  (hereinafter referred to as adhesive tub) by a partition  10   c;  a connecting opening  10   e  is provided in the partition  10   c  to allow the adhesive liquefied at the charging compartment  10   b  to flow into the adhesive tub  10   a.  This adhesive container  10  is composed of a tub-shaped tray comprising the charging compartment  10   b  and adhesive tub  10   a  and either formed from a material with high thermal-conductivity properties such as metal and the like, or a material with high workability properties such as resin and the like. A thermally conductive plate such as metal and the like is laid at the bottom surface. 
         [0048]    The applicator roller  30  is rotatably supported in the adhesive tub  10   a.  The applicator roller  30  is formed by a heat-resistant rubber material that has a superior impregnating property. The upper half of the applicator roller  30  projects upward from the adhesive tub  10   a,  and the lower half is disposed to be submerged in the liquefied adhesive in the adhesive tub  10   a.  (See  FIG. 1C ) Therefore, liquefied adhesive impregnates the applicator roller  30  at the lower half of the roller by the applicator roller  30  rotating. The upper half, projecting upward, applies the liquefied adhesive to the sheet bundle. A rotating shaft  31  of the applicator roller  30  is arranged longitudinally to the charging compartment  10   b  via the connecting opening  10   e,  and a stirring gear  32  that stirs the adhesive in the charging compartment  10   b  is mounted to this rotating shaft  31 . 
         [0049]    A forward and reverse-rotating motor (hereinafter called a stirring motor) M 1  is connected to the rotating shaft  31 . Therefore, the applicator roller  30  and stirring gear  32  are rotated by the rotational drive of the stirring motor M 1 . The applicator roller  30  stirs the adhesive in the adhesive tub  10   a,  and the stirring gear  32  stirs the adhesive in the charging compartment  10   b.    10   d  in  FIG. 1C  denotes a liquid adhesive holding portion disposed in the adhesive container  10   a.  This forms a basin to supply adhesive to the applicator roller  30  at a stable temperature so there is always an adequate amount of adhesive. 
         [0050]    An adhesive sensor  22   a  (hereinafter called adhesive amount detection means) is disposed in the liquid adhesive holding portion  10   d  to detect the temperature and amount of the liquefied adhesive.  22   a  in the drawing denotes a rod-shaped thermistor. This is disposed in the liquid adhesive holding portion  10   d  separated from the applicator roller  30 . This thermistor is composed of sintered fine-ceramic semiconductor heat-sensitive elements that use a variety of transition metal oxide materials such as Mn, Co, Ni, Fe, Cu and the like as the raw material. 
         [0051]    The adhesive sensor  22   a  in the drawing detects the surface of the adhesive (the remaining amount of adhesive) at the same time as detecting the temperature. In other words, this determines the amount of adhesive at a range (change of resistance value) that the detected temperature changes at the surface of the adhesive constantly heated to a temperature higher than room temperature to detect the remaining amount of adhesive. In such a case, the sensor  22   a  is disposed in the liquid adhesive holding portion  10   d  separated from the applicator roller  30  so that its detection of the surface of the adhesive is unaffected by the rotation of the applicator roller  30 . The adhesive sensor  22   a  is connected to a control CPU 60 , described below, to detect the near-empty state of the adhesive in the container (Lmin in the drawing) and an empty state (Lmax in the drawing). Note that the adhesive amount detection means of the present invention does not need to dual as a temperature sensor, and can, for example, be composed of a liquid surface sensor such as a float structure. 
         [0052]    Also,  34  denotes a control rod. This is disposed at a predetermined distance along an outer circumference of the applicator roller  30  in a lateral direction of the adhesive container  10 . This rod is attached at a predetermined distance from the outer surface of the applicator roller  30  to produce a uniform layer of adhesive around the roller surface. The distance of the control rod  34  to the surface of the applicator roller is adjusted according to the position of the sheet bundle.  36  denotes a plate-shaped blade. This is disposed a predetermined distance (doctor gap) from the outer circumference of the applicator roller  30  to sweep away excessive adhesive adhering to the outer circumference of the roller and to make the layer of adhesive uniform. 
         [0053]    Heating means  20  is installed in the adhesive container  10  that is configured as described above. The heating means  20  is composed of an electrically powered heater and high-frequency heating elements, and is embedded in the floor surface of the adhesive tub  10   a  of the adhesive container  10 . It is acceptable for this electrically powered heater  20  (hereinafter referred to as heating means) to be disposed in at least one of either the adhesive tub  10   a  or the charging compartment  10   b,  or in both. Also, it is acceptable to dispose an extra electrically powered heater in the charging compartment  10   b  to preheat the solid adhesive. 
         [0054]    The following will now explain heating temperature control of the heating means  20  (electrically powered heater) disposed in the adhesive tub  10   a.  Adhesive sensor  22   a,  described above, is disposed in the adhesive container  10 , also described above, and this sensor is composed to detect the liquid amount and the adhesive temperature at the same time. Also, a heating unit temperature sensor  22   b  that detects the temperature of the outer wall of the container heated by the heating means  20  is disposed in the adhesive container  10 . The heating unit temperature sensor  22   b  detects the temperature of the heating means, and controls the adhesive melting temperature along with the adhesive temperature sensor  22   a.  An erroneous temperature detection sensor, not shown, is disposed in the adhesive container  10 . When the adhesive and the adhesive container  10  storing that adhesive are heated to an excess temperature, it turns the unit power OFF. For that reason, these sensors are connected to a control CPU 60 , described below (see  FIG. 10 ). 
       Adhesive Application Unit Configuration 
       [0055]    The adhesive container  10  as described above has a reciprocating motion along the sheet bundle.  FIG. 3  is a conceptual diagram of the container. The adhesive container  10  is formed to a shorter length (dimension) than the bottom edge of the sheet bundle (the spine binding portion) SU. The container is supported on a guide rail  37  of the apparatus frame to move along the bottom edge SU of the sheet bundle along with the applicator roller  30  installed in that container. The adhesive container  10  is connected to a timing belt T installed on the apparatus frame; a drive motor M 2  is connected to the timing belt T. 
         [0056]    Therefore, drive motor M 2  reciprocates the adhesive container  10  between a home position HP and a return position RP where the return operation is started along the sheet bundle. Each position is set to the positional relationships shown in  FIG. 3 ; the return position RP is set based on sheet width size information. The adhesive container is set to the home position HP when the power is turned on (at device initialization). For example, this moves from the home position HP to the return position RP after a predetermined amount of time after a sheet grip signal from the grip sensor Sg of the gripping conveyance means  46 . At the same time as this movement, the roller stirring motor M 1  starts rotating the applicator roller  30 . Note that the home position sensor of the adhesive container  10  is denoted by the symbol SP in the drawing. 
         [0057]    With the adhesive applicator unit B configured as described above, rotation of the drive motor M 2  starts moving the adhesive container  10  from the left side of  FIG. 3  to the right side along the guide rail  37 . The amount of travel of the gripping conveyance means  46  is adjusted by the elevator motor (not shown) so that the applicator roller  30  pressingly contacts the sheet bundle to slightly separate the edges of the sheets in the advancing path, and forms a predetermined gap with the sheet bundle edge in the return path to return from the return position RP to the home position HP to apply adhesive. 
       Adhesive Application Unit Configuration 
       [0058]    Adhesive supply means  55  for supplying sold-form adhesive to the charging compartment  10   b  is disposed in the adhesive container  10  home position HP. As shown in  FIG. 2 , the adhesive supply means  55  is provided to refill adhesive to the charging compartment  10   b  with a signal (hereinafter referred to as a near-empty signal) from the liquid amount sensor  22   a.  This adhesive supply means  55  is composed of a hopper  56  that stores adhesive formed to a spherical-shape; a measuring mechanism  57  that measures the adhesive in the hopper at the same time as conveying it; and conveying pipe  58  that conveys adhesive from the measuring mechanism  57  to the charging compartment  10   b  of the adhesive container  10 . 
         [0059]    The hopper  56  is composed of a box-shape with an appropriate storage capacity, and is configured to store clumps of hot-melt adhesive inside and convey them from a conveyance outlet  56   a  on the bottom thereof. The measuring mechanism  57  is disposed in the conveyance outlet  56   a  on the bottom of the hopper, and is configured to feed adhesive from the conveyance outlet to a downstream feeding pipe while measuring the amount. One example of this structure is shown in  FIGS. 2A and 2B . The measuring mechanism  57  is composed of a measuring drum  57 . A measuring mechanism  57   b  that matches the outer diameter of the adhesive (the ball shapes shown in the drawing) on the outer circumference is disposed on the measuring drum  57   a;  a rotating shaft  57   c  is disposed at the center of the drum  57   a.  A control motor M 3  is linked to the rotating shaft  57   c.  Measuring channels  57   b  are disposed at three positions on the circumference of the measuring drum  57 . Five pieces of adhesive are stored in each measuring channel. Therefore, five pieces of adhesive are conveyed downstream when the drum  57   a  rotates ⅓; 10 pieces are conveyed downstream when the drum rotates ⅔; and 15 pieces of adhesive are conveyed downstream when the drum rotates one complete cycle. An empty sensor  59  and position sensor  59 S are disposed on the rotating shaft  57   c.  A control CPU 60 , described below, controls the angle of rotation of the measuring drum  57   a  and the number times of its rotation to feed a predetermined amount of adhesive to a downstream conveyance pipe  58 . 
         [0060]    The conveyance pipe  58  is configured to feed adhesive from the hopper  56  to the charging compartment  10   b  positioned at the home position. It is acceptable to dispose a vacuum fan, not shown, to intake molten gas dispersed from the charging compartment  10   b,  in the conveyance pipe  58 . In such a case, it is preferable to cover the conveyance outlet  56   a  at the outside wall of the measuring drum  57   a  so that molten gas does not enter the hopper  56 . 
       Adhesive Refilling Control Means Configuration 
       [0061]    Detection signals from the adhesive sensor  22   a  disposed in the adhesive container  10  and from the position sensor  59 S on the measuring drum  57   a  are transmitted to the control CPU 60 , but refill amount control means  62  are configured as described below with the control CPU 60 . A feature of the present invention is to set the adhesive refilling amount according to the number of applications of sheet bundles when the adhesive sensor  22   a  detects a near-empty state, when the refill amount control means  62  is continuously applying adhesive to sheet bundles. 
         [0062]    The following will now explain the refill amount control means  62  with reference to the refill control flow chart shown in  FIG. 8 . When the system is started (St 01 ), the initialization operation is executed (St 02 ). This initialization operation sets the activating units of the system to their preset initial states. For example, the adhesive container  10  is positioned at its home position HP by the signal from a sensor Sp. At the same time as the initializing of the activating units, heating means  20  raises the temperature of the adhesive in the adhesive container  10  to a predetermined degree (a temperature higher than the melting point of the adhesive). This is to set the adhesive remaining in the adhesive tub  10   a  of the adhesive container  10  to a predetermined melting temperature to change it from a solid state to a gel state. 
         [0063]    Here, the adhesive sensor  22   a  determines whether the adhesive container  10  is in a near-empty state (St 03 ). When the adhesive container  10  is determined to be in a near-empty state by the signal from the sensor  22   a,  adhesive is charged to the charging compartment  10   b  (St 04 ). The refilling amount of adhesive in this initialization process is preset. The adhesive in the adhesive tub  10   a  is set to “maximum refilling amount” to become Lmax. At the same time as adhesive is being charged to the container, the heating means  20  melts the solid adhesive in the charging compartment  10   b  to a predetermined temperature. Note that by the control motor M 3  rotating the measuring drum  57  of the adhesive supply means  55  only a preset rotating amount, the supply of adhesive to the charging compartment  10   b  is the “maximum refilling amount.” 
         [0064]    With such an initialization action, the temperature of the adhesive in the adhesive container  10  is raised to a predetermined degree, and adhesive is stored in the adhesive tub  10   a  to the amount that there is no near-empty state (Lmin). Note that near-empty (Lmin) is the maximum amount of adhesive consumed to ensure an adequate amount of adhesive needed for at least one sheet bundle (maximum size; maximum thickness), and is preset to an amount of adhesive that can be applied to the sheet bundle. This is so that the adhesive in the container does not enter an empty state while it is being applied to the sheet bundle. 
         [0065]    Next, the finishing mode (bookbinding process mode and the like), the number of copies, and the sheet size are set (St 06 ). An operator uses a control panel, which is an image-forming system, described below, to input the number of booklets to be created and the sheet sizes for these settings. 
         [0066]    Based on these settings, sheets printed with images at the image-forming device (St 07 ) are collated and stacked into sheet bundles on a stacking tray (St 08 ). The collated and stacked sheet bundle is shifted to the adhesive application position. Here, the drive motor M 2  is driven to reciprocate the adhesive container  10  along an edge of the sheet bundle. At the same time, the stirring motor M 1  is rotated to rotate the applicator roller  30 . In the outward movement of the adhesive container  10 , the edges of the sheets are separated, and a predetermined amount of adhesive is applied to the sheet bundle in the inward movement. The amount of adhesive applied at this time is adjusted by the gap (g shown in  FIG. 2 ) between the applicator roller  30  and the sheet bottom edge SU. If this gap g is set to be large (separated a predetermined distance), the amount of adhesive is low per units of surface area; if this gap g is set to be small (a near distance), the amount of adhesive is higher per units of surface area. 
         [0067]    Here, if the sheet bundle is thick, the amount of adhesive per unit area is large, or the amount of adhesive is adjusted depending on the sheet material. In other words, for sheet bundles that are difficult for the adhesive to penetrate between the leaves of sheets because the sheet bundle is thick or because of the material of the sheets (for example coated sheets), the cap is set to be low, and the adhesive amount is set to be higher. 
         [0068]    When the operation for coating the sheet bundle is ended, the refill amount control means  62  monitors detection signals from the sensor  22   a  for the amount of adhesive in the adhesive tub  10   a  (St 10 ). Monitoring of the adhesive amount is described below. The control CPU 60  executes the bookbinding process (St 11 ) and conveys the finished sheet bundle to the storage stacker. (St 12 ) There, the control CPU 60  calculates the remaining number (St 14 ), then returns to step St 07  to perform the same processes on subsequent sheets. 
         [0069]    When the processes are repeated to apply adhesive for the set number of sheet bundles (N) (“Yes” at St 13 ), then all processes are ended (St 15 ). 
       Refill Amount Control Means Configuration 
       [0070]    The refill amount control means  62  that is composed of the control CPU 60 , as described above, detects the amount of adhesive in the adhesive tub  10   a  at the point where the adhesive is applied to the sheet bundle (St 10  above). With this detection, adhesive is refilled, as shown below, when a near-empty state is detected. The refilling of the adhesive can be performed according to either one of embodiment 1, embodiment 2 or embodiment 3, described below. 
       Embodiment 1 
       [0071]    The first refilling method sets a plurality of refilling amounts that differ in levels for the amount of adhesive pre-filled, and one is selected with the remaining number of unprocessed sheets. As shown in  FIG. 9A , the remaining number of unprocessed sheets (St 21 ) is determined when a near-empty state is determined by the refill amount control means  62  with a detection signal from the adhesive sensor  22   a  (St 20 ). This determination is done by remaining sheets determining means  63 . The remaining sheets determining means  63  is configured to subtract the number of sheet bundles that have been coated with adhesive, from the “process number (N)” set at step  06 , for example. In other words, at step  14 , by executing “N−1,” the number of remaining unprocessed sheets is subtracted. 
         [0072]    Also, the refill amount control means  62  sets the plurality of refilling amounts that differ in levels, and stores that in memory means such as RAM and the like. The refilling amount is set in a plurality of levels such as “maximum refilling amount,” “middle refilling amount,” and “low refilling amount.” At this time, the maximum refilling amount is set to an amount where the adhesive in the adhesive tub  10   a  shifts from a near-empty state (Lmin) to a full state (Lmax). The middle refilling amount sets the amount of adhesive to a ⅔ position in the adhesive tub  10   a,  and the low refilling amount sets the adhesive in the adhesive tub  10   a  to a ⅓ position. 
         [0073]    There, the refill amount control means  62  selects one of either the “maximum refilling amount (Lmax),” the “middle refilling amount (Lm 1 ,” or the “low refilling amount (Lm 2 )” according to the number of unprocessed sheets to set the amount of adhesive to refill to the charging compartment  10   b  (St 22 ). The refill amount control means ( 62 ) is equipped with scheduled consumption amount calculation means  64  that calculates the scheduled consumption amount of adhesive (X×L) from the remaining number X of applications of unprocessed sheets and the adhesive amount (L) consumed for one sheet bundle. Based on this calculation result of the calculation means, the refilling amount is set to the maximum refilling amount when the calculated value exceeds the maximum refilling amount (Lmax). 
         [0074]    Also, if the calculated value of the calculation means  64  exceeds the low refilling amount (Lm 2 ), the refilling amount is set to the middle refilling amount (Lm 1 ). In the same way, if the calculated value is less than the low refilling amount (Lm 2 ), the refilling amount is set to the low refilling amount (Lm 2 ). Note that the amount of adhesive consumed (L) for one sheet bundle in the scheduled consumption amount calculation means  64  is preset to the standard amount based on (1) the standard application amount, or (2) calculated by multiplying the sheet length by the total sheet bundle thickness (or number of sheets) of unprocessed sheets. In other words, the scheduled consumption amount calculation means calculates the consumption amount of adhesive used thereafter from the remaining number of applications of unprocessed sheets and the amount of adhesive consumed on one sheet bundle. Also, the refilling amount of adhesive is set based on this calculated value. Therefore, the calculation of the scheduled consumption amount can be an approximate estimate. The simplest method can be (1) above, or by using method (2) above, it is possible to set the refilling amount by accurately finding the consumption amount. 
         [0075]    Based on the refilling amount set in this way, the maximum refilling amount (Lmax), the middle refilling amount (Lm 1 ) or low refilling amount (Lm 2 ) are used to refill the adhesive by controlling angle, number of rotations and the rotation of the measuring drum  57 . 
       Embodiment 2 
       [0076]    The second refilling method calculates the total consumption amount of unprocessed sheets and sets the refilling amount based on that calculated value. As shown in  FIG. 9B , the remaining number of unprocessed sheets (St 21 ) is determined when a near-empty state is determined by the refill amount control means  62  with a detection signal from the adhesive sensor  22   a  (St 20 ). This determination is performed by the remaining sheets determining means  63 ; the remaining sheets determining means  63  has the same configuration as that described in relation to the first embodiment. 
         [0077]    The “maximum refilling amount” where the adhesive is full in the adhesive tub  10   a  is preset in the refill amount control means  62 . The refill amount control means  62  is equipped with calculation means  64  that calculates the scheduled total consumption amount of adhesive (X×L) from the remaining number X of applications of unprocessed sheets and the adhesive amount (L) consumed for one sheet bundle. Based on this calculation result of the calculation means, the refilling amount is set to the maximum refilling amount when the calculated value exceeds the maximum refilling amount (Lmax) (St 21 ). For that reason, the refill amount control means  61  has comparing means  65  that compare the calculation results from the calculation means and a preset maximum refill amount. 
         [0078]    Also, when the calculated value of the calculation means  64  exceeds the maximum refill amount, the adhesive refill amount is set to the calculated value (preset total consumption amount) calculated by the calculation means  64 . (St 21 ) The amount of adhesive consumed (L) for one sheet bundle in the scheduled consumption amount calculation means  64  is (1) preset to the standard amount based on the standard application amount, or (2) calculated by multiplying the sheet length by the total sheet bundle thickness (or number of sheets) of unprocessed sheets. For (2) above, either the standard application thickness (thickness of the adhesive layer) is multiplied by the total surface area (total bundle thickness×total application length) or multiples the application thickness set from the sheet material. 
         [0079]    In this way, the scheduled consumption amount calculation means calculates the consumption amount of adhesive used thereafter from the remaining number of applications of unprocessed sheets and the amount of adhesive consumed on one sheet bundle. Also, the adhesive equivalent to this calculated value is refilled into the adhesive tub  10   a.  The refilling control controls the measuring drum  57  in the same way as described in relation to the first embodiment. 
       Image-Forming System Configuration 
       [0080]    The overall configuration of the image-forming system will now be explained in relation to  FIG. 4 . The essential portion thereof is shown in  FIG. 5 . This system is composed of a printing unit C and the bookbinding unit A that binds into booklets printed sheets conveyed from the printing unit C. A stacker D that stores unbound printed sheets is installed next to the bookbinding unit A. This printing unit C is composed of a known structure such as a printer or photocopier and the like. A predetermined sheet is kicked out of a cassette in a feeder unit  40  and is printed by a printing drum  41 . After the image is fused to the sheet by a fuser  42 , then conveyed out from a discharge outlet  43 . The printing drum  41  in the drawing is a photoreceptor drum. This uses a static electric printing method that forms a static electric latent image on the surface of the drum using a laser oscillator and transfers that image to the sheet. Other printing methods such as a silk screen printing method, ink-jet printing method can be adopted. 
         [0081]    Printed sheets sequentially output from the discharge outlet  43  are collated into a predetermined number of sheets and aligned at the stacking tray  44  in the bookbinding unit A. The symbol  45  in the drawing denotes a sheet conveyance-in path that guides the printed sheets from the discharge outlet  43  to the stacking tray  44 . Sheets collated and aligned on the stacking tray  44  are conveyed to the adhesive application position E by gripping conveyance means  46 . Of particular note, the stacking tray  44  is disposed to be in a substantially lateral orientation; the bookbinding path  47  that conveys the sheet bundle using the gripping conveyance means  46  is disposed to be substantially longitudinal. The gripping conveyance means  46  is composed of a pair of gripping means that nip the sheet bundle at its front and back sides and change the orientation of the sheet bundle from a lateral state to a longitudinal state and convey the sheet bundle in a longitudinal direction along the bookbinding path  47 . 
         [0082]    Also, a cover sheet conveyance path  48  that conveys a cover sheet is connected to a sheet conveyance-in path  45 ; a sheet conveyance-out path  49  is connected to the cover sheet conveyance path  48 . In other words, a printed sheet conveyed from the discharge outlet  43  of the printing unit C is conveyed from the sheet conveyance-in path  45  to the stacking tray  44 , and a cover sheet conveyed from the discharge outlet  43  is supplied to the cover sheet conveyance path  48  that branches from the sheet conveyance-in path  45 . At the same time, printed sheets that do undergo the binding operation are conveyed from the discharge outlet  43  through the sheet conveyance-in path  45 , cover sheet conveyance path  48  and into the stacker unit D from the sheet conveyance-out path  49 , traversing the bookbinding unit A. 
         [0083]    The bookbinding path  47  and cover sheet conveyance path  48  are disposed to mutually intersect each other. The sheet bundle conveyed from the bookbinding path  47  and the cover sheet conveyed from the cover sheet conveyance path  48  are joined at the cover sheet binding position F (see  FIG. 4 ). In other words, the cover sheet HS is conveyed to the cover sheet binding position F so that its center line is aligned to the intersecting point and the sheet bundle is touched to the cover sheet in an upside-down T-shape from the bookbinding path  47  that is perpendicular to the sheet bundle. Folding rollers  53   c  disposed in the bookbinding path  47  downstream of the cover sheet binding position F fold the cover sheet to encase the sheet bundle. The adhesive application unit B is built-in upstream of the cover sheet binding position F. 
         [0084]    The sheet bundle sandwiched by the gripping conveyance means  46  and held in an upright orientation at the adhesive application position E so that its bottom edge is coated with predetermined amount of adhesive. The adhesive container  10  explained with references to  FIGS. 1 to 3  in the adhesive application unit B is capable of moving along the bottom edge SU of the sheet bundle. The adhesive container  10  provided the heating means  20  has the same configuration as was described above. Therefore, an explanation thereof will be omitted. 
       Explanation of Bookbinding Operation 
       [0085]    The bookbinding unit A configured as described above and bookbinding operations will now be explained with references to  FIGS. 6 and 7 . As shown in  FIG. 6A , the adhesive container  10  is supported on the guide rail  37  and driven by the drive motor M 2  to move along a longitudinal direction of the sheet bundle held by the gripping conveyance means  46 . 
         [0086]    The adhesive container  10  can move in the longitudinal direction along the spine portion of the sheet bundle (a direction orthogonal to the bundle thickness) and the applicator roller  30  built-in to the adhesive container  10  is rotated in a predetermined direction, for example in a direction reverse to the adhesive container  10  direction of movement. Adhesive on the applicator roller  30  is applied to the spine portion of the sheet bundle (see the state shown in  FIG. 6A ). Next, after the coating process, the adhesive container  10  is retreated to its outside home position HP from the conveyance path of the sheet bundle in the state shown in  FIG. 6B . 
         [0087]    The sheet bundle coated with adhesive is conveyed to the cover sheet binding position F by the gripping conveyance means  46  and is joined to the cover sheet HS fed from the cover sheet conveyance path  48 . (See the state shown in  FIG. 7A .) After both are joined, spine folding pressing means  53   a  disposed in the cover sheet binding position F fold the cover sheet. (See the state shown in  FIG. 7B .) Then, the sheet bundle is bound into a booklet by the folding rollers  53   c,  and when necessary, a trimming unit  50  downstream of the folding rollers  53   c  trims true edges of the bound sheet bundle. Note that  53   b  denotes a spine pressing plate disposed in the cover sheet binding position F. This is configured to project into and retreat from the bookbinding path  47 . Then, the sheet bundle bound with a cover sheet is stored in a storage stacker  51 . 
         [0088]    Note that in the foregoing embodiment, an explanation was provided for the cover sheet HS to be conveyed in the same way as a printed sheet from the discharge outlet  43  after it has been printed with a title and the like at the printing unit C, but it is also acceptable to install an inserter between the printing unit and bookbinding unit A to supply the cover sheet HS from the inserter to the sheet conveyance-in path  45 . The inserter can be composed of one or a plurality of trays, a separating roller to separate sheets on the tray into single sheets, and a sheet supply path to guide the sheet from the separating roller to the sheet conveyance-in path  45 . 
         [0089]    Also, the stacker unit D is composed of a discharge tray that sequentially stacks and stores sheets conveyed from the conveyance outlet  52  of the sheet conveyance-out path  49  connected to the cover sheet conveyance path  48 . This unit can also be equipped with a finishing unit to staple, punch holes or apply marks to sheets conveyed from the conveyance outlet  52 . This finishing unit can also adopt any known and preferred mechanisms. 
       Configuration of Control Means 
       [0090]    The following will explain the control of the image-forming system described above.  FIG. 10  is a block diagram of a control configuration of the bookbinding unit. The control unit of the bookbinding unit is composed of a control CPU 60 . The control CPU 60  runs bookbinding process operations by loading programs that run the bookbinding processing operation from ROM (not shown). An adhesive refilling control program  67  and temperature control program  69  that controls the temperature of the adhesive are included in the ROM. Control data required for each control are stored in ROM. Control data  68  relating to adhesive refilling and control data  70  relating to temperature control are included in RAM. 
         [0091]    The adhesive sensor (liquid temperature sensor and liquid amount sensor)  22   a  and heating unit temperature sensor  22   b  are connected to the control CPU 60 . These are configured to send detection signals thereto. Also, a position sensor  59 S (not shown) that detects the encoder  59  is connected to the control CPU 60 . 
         [0092]    The application motor (stirring motor) M 1 , drive motor M 2  and control motor M 3  are linked to control CPU 60  via a drive circuit to control drive. Furthermore, the control CPU 60  composes the remaining sheets determining means  63 , scheduled consumption amount calculation means  64 , and the comparison means  65 . The remaining sheets determining means  63  receives information of the number of units to be processed from the image-forming unit and each time adhesive is applied to the sheet bundle, a unit is subtracted (N−1) from the total number of processes (N). The scheduled consumption amount calculation means  64  is configured to calculate the scheduled consumption amount of unprocessed sheets from the sheet size information received from the image-forming unit and page count information. This calculation find the total application length from the sheet size information by calculating the total page thickness from the total number of pages of unprocessed sheets. Also, by multiplying (number of remaining unprocessed sheets), (total bundle thickness) and (total application length) by (standard adhesive application layer thickness), it is possible to calculate the total amount of adhesive that will be consumed thereafter. 
         [0093]    The comparison means  65  is composed by a comparator that compares a calculation value of the preset maximum refilling amount of adhesive and the scheduled consumption amount calculation means  64 . 
         [0094]    This application claims priority rights from Japanese Pat. App. No. 2007-305739, which is herein incorporated by reference.