Abstract:
Bookbinding unit to avert sheets coming loose and other problems that, due to adhesive leakage in coating an adhesive onto a sheaf and pasting on a cover sheet, lead to poor binding. Provided with unit housing, sheaf retainer for retaining in an adhesive-application position sheets collated into book blocks, adhesive container for storing hot-melt adhesive, heater built-in to the adhesive container for melting the adhesive at a predetermined temperature, temperature controller for controlling the heater, applicator for applying adhesive to sheaves, and cover binder disposed downstream of the adhesive-application location for binding sheaves coated with adhesive together with cover sheets. The controller has a first sensor for detecting the adhesive temperature the adhesive container, and a second sensor for detecting ambient temperature inside the unit housing, and controls the heating temperature of the heater according to the temperatures detected by the first and second sensors.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention—involving bookbinding units and image-forming systems that collate and compile sheets conveyed out of an imaging device or similar machine, coat the spine-portion edge of the sheets with adhesive, and bind the sheets together with a cover sheet—relates to improvements in temperature control in the melting of hot-melt adhesive at a predetermined temperature. 
         [0003]    2. Description of the Related Art 
         [0004]    In general, bookbinding units of this sort are known broadly as terminal devices for digital printers, printing machines, or other imaging apparatus, and as devices that stack in page order sheets onto which images have been formed (“printed sheets” hereinafter), collate the sheets into a bundle, and finish the bundle into a booklet by applying adhesive to its saddle-stitched edge-face and binding the bundle together with a cover sheet. Employed therein for the unit that applies the adhesive are an adhesive container for storing adhesive, and a structural makeup for melting the solid adhesive with a built-in heating means in the container and for applying the liquefied adhesive to one edge of a sheet bundle with an applicator roller. 
         [0005]    Thus, the system (hot-melt adhesive) whereby the container is provisioned with a solid adhesive and then the adhesive is thermally dissolved features ease of adhesive handling, but special care must be taken to govern the post-melting temperature in the adhesive container. For example, the melting point for routinely employed solid adhesives is some 60° C. to 80° C., while in applying the adhesive to sheets or other articles to be glued, the adhesive must be kept at optimum temperature, such as 140° C. to 150° C. This is because secure adhesion requires that the adhesive penetrates between and bonds the leaves of booklet sheets. 
         [0006]    In this case, if the temperature of the adhesive is higher than the optimum temperature, the adhesiveness will be weak (it will have low viscosity), leading to the troublesome situation of the adhesive dripping or splattering and soiling the cover sheets, etc. in the course of the adhesive being applied to sheet bundles. Also, if the temperature of the adhesive is lower than the optimum temperature, secure adhesion will not be attained, causing sheets to come loose or giving rise to similar problems. Along with these problems, the melting conditions (time) for a hot-melt adhesive differ between when the amount charged into the adhesive container is large-volume and when it is small-volume. Furthermore, the adhesive in the container hardens when the unit is not in use and the hardened states differ depending on the ambient temperature, yet hardened or freshly injected adhesive must be melted swiftly and retained at a predetermined temperature when the bookbinding unit or similar device is started up. 
         [0007]    Proposals to date for this sort of temperature control of solid adhesive include, in Japanese Unexamined Pat. Pub. App. No. 2005-238526, the provision of a heat-retaining mode for when the unit is not in use. This publication discloses a heat-retaining mode that maintains the adhesive container for an adhesive paste at a temperature lower than the application temperature in situations where a standby state in the bookbinding unit, in which the adhesive paste has not been coated onto a sheet bundle, has persisted. 
         [0008]    Furthermore, Japanese Unexamined Pat. Pub. App. No. 2003-010748 discloses a heating method in which an electromagnetic induction coil is furnished in the adhesive container to melt an adhesive paste inside with the Joule heat from eddy currents stemming from high-frequency magnetic flux applied to the coil. The current supplied to the coil is adjusted according to the paste temperature detected by a sensor (thermistor) provided in the adhesive container. 
         [0009]    As discussed above, in bookbinding unit and similar devices methods have been adopted to detect the temperature of the adhesive in the container using a sensor and then raise the temperature of the adhesive to an optimum, predetermined degree when adhesive is being applied to a sheet bundle. In this case, if the adhesive temperature is too high when adhesive is being applied to a sheet bundle, the adhesive can drip or splatter, soiling cover sheets, etc. The adhesive can also stick to places other than the spine portion, leading to poor-quality book-forming. Also, conversely, if the adhesive temperature is too low, the adhesive applied to the saddle-stitched edge-face will fail to penetrate between the individual leaves of sheets. An insufficient amount of adhesive between the sheets causes poor binding and leads to sheet inner leaves coming loose and falling out of the bound booklet. 
         [0010]    Conventionally, the adhesive temperature in the container has been associated with poor binding, so an attempt has been made to control the adhesive temperature to the optimum level. However, the overall temperatures of the sheet bundle and cover sheet also affect the quality of the binding. The ambient temperature when the adhesive is being applied, and the ambient temperature when an adhesive-coated sheet bundle is being bound into a cover sheet also affect the quality of the binding. 
         [0011]    For example, if the temperature of the sheet bundle is low, the adhesive will not adequately penetrate the inner leaves of a sheet bundle. In such a case, sheets that have not been adequately glued may fall out of the booklet later. If the cover sheet temperature is too low, the adhesive can harden prematurely. Wrinkles and other deformities such as unevenness can result when the cover sheet is folded to encase the sheet bundle. Also, if the sheet bundle temperature is too high, an excess amount of adhesive can penetrate between the inner leaves of the sheet bundle, again degrading the quality of the final binding. If the cover sheet temperature is too high, adhesive can leak out when the cover sheet is folded over the sheet bundle to form the booklet. 
         [0012]    However, the ambient temperatures when coating the edges of the sheet bundle with adhesive, and when binding the sheet bundle to the cover sheet also affect the quality of the binding. For example, if the ambient temperature is too high when the adhesive is being applied to the cover sheet, the adhesive can drip or splash. Conversely, if that temperature is too low, the surface of the adhesive layer can harden, causing a film to develop over the layer, which prevents the adhesive from properly getting between the inner leaves of the sheet bundle. Also, if the ambient temperature is too high when affixing a cover sheet to a sheet bundle, adhesive can leak. If the ambient temperature is too low, the spine portion of the cover sheet can be wrinkled or otherwise defaced when it is folded. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    Therein, inventors arrived at the concept of detecting the influence of the sheet-leaf temperature of a (saddle-stitched) sheaf, and the ambient temperature during adhesive application, as well as the sheet-leaf temperature of the cover, and the ambient temperature when cover is being pasted on—detecting the device-internal ambient temperature—to control the temperature of the adhesive inside the container. 
         [0014]    An object of the present invention is to provide a bookbinding unit that does not cause a problem such as sheets falling out of the bound sheet bundle and at the same time cause a poor binding because of adhesive leakage, when coating the sheet bundle with adhesive and binding that to the cover sheet. 
         [0015]    Another object of the present invention is to provide a bookbinding unit that can control the temperature of the adhesive in the container with a simple structure to conditions appropriate for the temperature of the inner leaves of the sheet bundle, the temperature of the cover sheet, and the ambient temperature of the bookbinding process. 
         [0016]    The present invention employs the following configuration to solve the aforementioned problems. Unit housing, sheet bundle holding means for holding the sheets collated into a sheet bundle at an adhesive-application location, an adhesive container that stores hot-melt adhesive, heating means built-in to the adhesive container for melting the adhesive at a predetermined temperature, temperature control means for controlling the heating means, applicator means for applying adhesive to the sheet bundle, and cover sheet binding means disposed downstream of the adhesive-application location for binding the sheet bundle coated with adhesive to the cover sheet are provided. The control means has a first sensor means for detecting the temperature of the adhesive in the adhesive container, and a second sensor means for detecting the ambient temperature inside the unit housing. The control means controls the heating temperature of the heating means according to the temperatures detected by the first and second sensor means. 
         [0017]    The temperature control means raises the temperature of the adhesive to a predetermined degree when the temperature detected by the second sensor means is higher than a predetermined degree. The temperature control means raises the temperature of the adhesive to a predetermined degree when the temperature detected by the second sensor means is lower than a predetermined degree. 
         [0018]    The second sensor means is disposed near the cover sheet binding position either to detect the ambient temperature of the sheet bundle bound to the cover sheet, or the sensor means is disposed near the adhesive-application location to detect the ambient temperature of the sheet bundle coated with adhesive. 
         [0019]    When the second sensor means is disposed near the adhesive-application location, the adhesive container is configured to reciprocate along the edge of the sheet bundle held at the adhesive-application location. Also, the second sensor means is disposed either outside the range of movement of the adhesive container, or it is disposed to detect the temperature inside the unit when the adhesive container is positioned away. 
         [0020]    An image-forming unit that has image-forming means for sequentially forming images on sheets, and a bookbinding unit that collates into sheet bundles sheets conveyed from the image-forming unit, coats an edge of the sheet bundle with adhesive and binds the sheet bundle to a cover sheet are provided. The bookbinding unit has a stacking means for collating into sheet bundles sheets conveyed from the image-forming means, and has the configuration described above. 
         [0021]    The present invention is equipped with temperature control means for controlling the temperature of the adhesive in the container, the first sensor means for detecting the temperature of the adhesive in the container, and the second sensor means for detecting the ambient temperature in the unit housing, the control means controls the heating means of the adhesive container according to the temperatures detected by the first and second sensor means. These have the following effects. 
         [0022]    The ambient temperature in the unit housing is detected, so when the ambient temperature is lower than a predetermined degree, the adhesive temperature in the container is raised to a predetermined degree. Therefore, when the temperature of the inner leaves of the sheet bundle and the ambient temperature for coating the sheet bundle with adhesive are low, the adhesive temperature is raised so the problem of sheets coming loose and falling out of the bound booklet does not occur because adhesive can adequately permeate between the leaves of sheets. Similarly, if the cover sheet at the cover sheet binding position is low temperature, even if the ambient temperature is low when binding the cover sheet, the adhesive temperature is raised so the adhesive does not prematurely harden which can cause wrinkles or other deformations of the cover sheet. 
         [0023]    Furthermore, if the second sensor means that detects the ambient temperature in the unit housing is disposed to detect the ambient temperature of the bound sheet bundle, it is possible to control the adhesive temperature so that it is at the proper temperature when the cover sheet is bound to encase the sheet bundle and when the cover sheet is folded to encase the sheet bundle. Therefore, wrinkles or other unevenness do not occur in the spine portion of the cover sheet if the adhesive temperature is low when the cover sheet is being folded. Also, adhesive does not leak out of the binding when folding the cover sheet if the adhesive temperature is high. 
         [0024]    By disposing the second sensor means that detects the ambient temperature in the unit housing near the adhesive-application location, it is possible to control the temperature so that surface of the adhesive layer will not harden and form a film when the adhesive is being applied to the edge of the sheet bundle. Therefore, the adhesive layer on the sheet bundle edge will not harden and be prevented from penetrating between the inner leaves of the sheet bundle. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0025]      FIGS. 1A to 1C  are explanatory views of an adhesive application unit used in a bookbinding unit 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; 
           [0026]      FIG. 2  is an overall view of an image-forming system installed with the adhesive application unit; 
           [0027]      FIG. 3  is an explanatory view showing in detail the bookbinding unit in the system shown in  FIG. 2 ; 
           [0028]      FIG. 4  is a structural chart of an adhesive application operation in the adhesive container shown  FIG. 1 ; 
           [0029]      FIGS. 5A and 5B  are explanatory views of a bookbinding operation in the system shown in  FIG. 3 ;  5 A shows a state of adhesive being applied to a spine of a sheet bundle;  5 B shows a state where the sheet bundle being joined to a cover sheet; 
           [0030]      FIGS. 6C and 6D  are explanatory views of the bookbinding operation in the system shown in  FIG. 3 ;  6 C shows an initial state of the sheet bundle and cover sheet being bound;  6 D shows a state where the cover sheet is being folded over and covering the sheet bundle; and 
           [0031]      FIG. 7  is a block diagram of a configuration of a temperature control means for the adhesive in the unit shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    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 4 .  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. 2  is an overall view of bookbinding unit with a built-in adhesive application unit and an image-forming system.  FIG. 3  is a view of the essential portion of the bookbinding unit shown in  FIG. 2 . 
       Adhesive Application Unit Configuration 
       [0033]    The adhesive application unit B shown in  FIG. 1A  is composed of an adhesive container  10  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 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 down at the bottom surface. 
         [0034]    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 . Therefore, liquefied adhesive impregnates the applicator roller  30  at the lower half of the roller by the applicator roller  30  being rotated. 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, and a stirring gear  32  that stirs the adhesive in the charging compartment  10   b  is mounted to this rotating shaft  31 . 
         [0035]    A forward and reverse-rotating stirring motor M 1  is connected to the rotating shaft  31 . Therefore, the applicator roller  30  and stirring gear  32  are rotated by rotatingly driving the stirring motor M 1 . The applicator roller  30  stirs the adhesive in the adhesive container  10 , and the stirring gear  32  stirs the adhesive in the charging compartment  10   b .  10   d  in the drawing denotes a liquid adhesive holding portion disposed in the adhesive container  10 . This forms a basin for supplying adhesive to the applicator roller  30  at a stable temperature so there is always an adequate amount of adhesive. 
         [0036]    An adhesive temperature sensor  22   a  (first sensor means) is disposed in the liquid adhesive holding portion  10   d  to detect the temperature of the liquefied adhesive. The adhesive temperature sensor  22   a  is composed of a rod-shaped thermistor and 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. 
         [0037]    The adhesive temperature 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 using the change in temperature of 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 adhesive temperature sensor  22   a  is disposed in the liquid adhesive holding portion  10   d  separated from the applicator roller  30  so that the detection of the surface of the adhesive by the adhesive temperature sensor  22   a  is unaffected by the rotation of the applicator roller  30 . 
         [0038]    Also,  34  denotes a control rod. This is disposed 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. Reference numeral  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. 
         [0039]    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 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 the electrically powered heater in the charging compartment  10   b  to preheat the solid adhesive. 
         [0040]    The following will now explain heating temperature control of the heating means  20  (electrically powered heater) disposed in the adhesive tub  10   a . The adhesive temperature sensor  22   a  (first sensor means) is disposed in the adhesive container  10  to detect the temperature of the adhesive liquefied in the adhesive tub  10   a . Also, a heating unit temperature sensor  22   b  that detects the temperature outside of the container heated by the heating means  20  and an erroneous temperature detection sensor, not shown, are 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  (first sensor means). The erroneous temperature detection sensor is disposed in the adhesive container  10  for example and detects when the adhesive and the adhesive container  10  containing the adhesive have been over heated and executes a safety measure such as turning off the power to the device. For that reason, these sensors are connected to a control CPU  26  (see  FIG. 7 ). 
       Temperature Control Means Configuration 
       [0041]    The control CPU  26  shown in  FIG. 7  is provided as control means of the bookbinding unit A. This control CPU  26  calls up a heating control execution program  28  (ROM) to control the voltage (or current) supplied to the heating means  20 . This composes temperature control heating means that adjusts the temperature of the adhesive in the adhesive container  10 . Data for executing the heating operation (such as a target temperature that sets the charged current value, charging time, timer setting and the like) are provided in a data table  29  (RAM). A power supply  21  (DC power in the drawing) and pulse generator  23  are connected to the electrically powered heater (heating means)  20  disposed in the adhesive container  10 ; the pulse generator  23  composed of the control CPU  26 . In other words, pulse currents that correspond to the command signals emitted from the temperature control means (control CPU)  26  are supplied to the electrically powered heater  20 . A power supply circuit  24  provided the pulse generator  23  is composed of a PWM (pulse width modulation) circuit and is configured to vary the voltage by changing the pulse width of the power supply using command signals from the control CPU  26 . 
         [0042]    The adhesive container  10  as described above has a reciprocating motion along the sheet bundle.  FIG. 4  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 backside covered at the binding process) 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. 
         [0043]    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. 4 ; the return position RP is set based on sheet width size information. The adhesive container  10  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 stirring motor M 1  starts rotating the applicator roller  30 . Note that the home position sensor of the adhesive container  10  is given the symbol SP in the drawing. 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. 4  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. 
       Image-Forming System Configuration 
       [0044]    The image-forming system shown in  FIG. 2  is composed of a printing unit C and the bookbinding unit A that binds into a booklet 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 , the sheet is 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. 
         [0045]    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 location 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 . 
         [0046]    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 . Also, 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. 
         [0047]    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. 3 ). 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. 
         [0048]    The sheet bundle sandwiched by the gripping conveyance means  46  and held in an upright orientation at the adhesive-application location E so that its bottom edge is coated with predetermined amount of adhesive. The adhesive container  10  explained with references to  FIGS. 1 to 4  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 
       [0049]    The bookbinding unit A configured as described above and bookbinding operations will now be explained with references to  FIGS. 5 and 6 . As shown in  FIG. 5A , 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 . 
         [0050]    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. 5A ). 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. 5B . The second sensor means  22   c , described below, detects the ambient temperature of the adhesive-application location E when the adhesive container  10  is at its home position HP. 
         [0051]    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. 6C .) After these 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. 6D .) 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 . 
         [0052]    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 . 
         [0053]    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 for Detecting Unit-Internal Ambient Temperature 
       [0054]    With the configuration described above, the present invention controls the temperature by detecting the temperature in the unit when controlling the temperature of the adhesive in the adhesive container  10 . For that reason, the second sensor means  22   c  ( 22   d ) that detects the ambient temperature in the unit housing as shown in  FIG. 3  is disposed in the unit housing A. As shown in the drawing, the second sensor means  22   c  is disposed in the adhesive-application location E, and the second sensor means  22   d  is disposed in the cover sheet binding position F. In other words, the second sensor means  22   c  and  22   d  that detect the ambient temperature inside the unit housing are disposed in the adhesive-application location E and the cover sheet binding position F. Their positions are shown in  FIG. 3 . The second sensor means  22   c ,  22   d  are composed of a thermistor or thermocouple, or the like. 
         [0055]    Particularly, the second sensor means can, for example, be disposed separated from the range of the movement of the reciprocating adhesive container  10 , or this sensor can detect the temperature when the adhesive container  10  when the adhesive container  10  has far traveled away from the position of the sensor means so that the sensor is unaffected by the adhesive temperature heated in the adhesive container  10  that reciprocates between the home position HP and the return position RP shown in  FIG. 4 . The second sensor means  22   c  shown in  FIG. 4  is disposed near the return position RP and is configured to detect the ambient temperature when the adhesive container  10  is positioned at its home position HP. At least one of the second sensor means  22   c ,  22   d  disposed in the adhesive-application location E and cover sheet binding position F is wired to transmit the detected temperature to the control CPU  26  described above. 
         [0056]    Also, the temperature control means composed of the control CPU  26  controls the heating means  20  to raise the temperature of the adhesive to a predetermined degree when the temperature detected by the second sensor means  22   c ,  22   d  is higher than a predetermined degree, and to raise the temperature of the adhesive to a predetermined degree when the temperature detected by the second sensor means  22   c ,  22   d  is lower than a predetermined degree. 
         [0057]    This application claims priority rights from Japanese Pat. App. No. 2007-200509, which is herein incorporated by reference.