Abstract:
An adhesive application mechanism for a printer is provided. The adhesive application mechanism comprises first and second adhesive applicators, the adhesive applicators being mutually opposed and configured to apply adhesive simultaneously onto opposite faces of sheets of print media fed therebetween, wherein a media feed path is defined between the first and second adhesive applicators.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This is a Continuation (or Continuation-in-Part) of Ser. No. 10/791,727 filed on Mar. 04, 2004 which is a continuation of Ser. No. 10/126,676 which is a Continuation of Ser. No. 09/721,856 all of which are herein incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The following invention relates to a printer. More particularly, this invention relates to a printer that incorporates a binding apparatus for binding sheets.  
       BACKGROUND OF THE INVENTION  
       [0003]     It is well known to print individual sheets of a volume to be bound, place all of the printed sheets into a stack, crop one or more edges of the stack and to bind the sheets together by applying a binding adhesive to an edge of the stack of sheets. This is a time consuming and labour-intensive process.  
         [0004]     It would be more efficient to provide pre-cut, uniformly sized sheets, print one or both surfaces of each sheet and provide a strip of binding adhesive to one or both surfaces of each sheet adjacent the edge to be bound. Then the printed and pre-glued sheets can be placed accurately in a stack, and the sheets adjacent the spine pressed so that the adhesive binds the sheet edges together.  
         [0005]     It would also be desirable to provide an apparatus and method for applying a strip or strips of binding adhesive to a sheet as the sheet passes through a printer.  
       SUMMARY OF THE INVENTION  
       [0006]     According to a first aspect of the invention, there is provided a printer which comprises 
        a roller assembly for feeding sheets of print media along a feed path;     a print head positioned downstream of the roller assembly for carrying out a printing operation on the sheets of print media;     an adhesive application mechanism positioned downstream of the print head and comprising first and second aligned adhesive applicators that are positioned on opposite sides of the feed path and are configured to apply adhesive simultaneously to the sheets of media as the sheets pass between the applicators along the feed path, such that the sheets each have aligned strips of adhesive on respective sides;     a support structure positioned downstream of the adhesive application mechanism and defining a floor onto which sheets to be bound are conveyed and a wall that extends from the floor to define a stop for the sheets that are fed onto the floor; and     a binding mechanism arranged on the support structure and displaceable with respect to the support structure to act on each sheet fed into the support structure such that the sheets are adhered together with the strips of adhesive.        
 
         [0012]     The adhesive applicators may be opposed, pivotally mounted applicators that are capable of being pivoted so that their tangential speed matches a speed at which the sheets are fed along the feed path.  
         [0013]     The adhesive applicators may be opposed adhesive applicator rollers that are displaceable towards the feed path to apply the adhesive and away from the feed path when adhesive application is not required.  
         [0014]     The adhesive applicators may be opposed adhesive spray applicators to spray the adhesive onto respective opposed sides of the sheets.  
         [0015]     One adhesive applicator may be configured to apply one part of a two-part adhesive, while the other adhesive applicator may be configured to apply another part of the two-part adhesive.  
         [0016]     The support structure may include a frame and a tray that is suspended from the frame.  
         [0017]     The binding mechanism may include a vibration imparting mechanism for imparting vibratory motion to the support structure to facilitate alignment of the sheets in the support structure.  
         [0018]     The binding mechanism may include a binding press that is positioned above the support structure to be aligned with leading edges of stacked sheets. The binding press may be operable to urge said leading edges against each other so that the adhesive serves to bind the sheets together.  
         [0019]     According to a second aspect of the invention, there is provided a method of generating bound documents, the method comprising the steps of: 
        conveying sheets of a print medium through a printing station;     carrying out a printing process on the sheets in the printing station;     conveying the sheets through an adhesive application station;     applying adhesive to each sheet proximate an edge of each sheet in the adhesive application station;     stacking a predetermined number of the sheets at a stacking station, so that respective strips of adhesive are aligned with each other; and     performing a binding operation on said predetermined number of sheets so that said predetermined number of sheets are bound together to define a document.        
 
         [0026]     The step of carrying out a printing process on the sheets may comprise ejecting ink from an ink jet printhead on to the sheets.  
         [0027]     The step of applying adhesive to the sheets may comprise the step of applying at least one adhesive strip to an edge of each sheet to be bound, while the sheet moves through the adhesive application station.  
         [0028]     The adhesive strip may be applied to each sheet by ejecting the adhesive from an adhesive applicator positioned at the adhesive application station without the adhesive applicator making contact with the sheet.  
         [0029]     The adhesive may be sprayed on to each sheet. In particular, the adhesive may be sprayed on to both sides of the sheet to apply the adhesive strip to each side of the sheet.  
         [0030]     Instead of spraying the adhesive, the method may include the step of bringing at least one adhesive applicator into contact with the sheet while the sheet passes through the adhesive application station.  
         [0031]     In one embodiment, the method may include the step of bringing a pair of opposed adhesive applicators into contact with the sheet so that the adhesive strip is applied to each side of the sheet. In particular, the method may include the step of bringing a pair of opposed adhesive applicator rollers into contact with the sheet so that the adhesive strip is applied to each side of the sheet.  
         [0032]     The, or each, adhesive strip may be applied to a trailing edge of each sheet. Instead, the, or each, adhesive strip may be applied to a leading edge of each sheet.  
         [0033]     The step of stacking the sheets may include feeding the sheets into a stacking tray of the stacking station, so that the sheets bear against a part of the stacking station, with the adhesive strips of the sheets aligned with respect to each other.  
         [0034]     The step of performing the binding operation may include the step of applying pressure to the stacked sheets at a position aligned with the adhesive strips of the stacked sheets so that the adhesive strips serve to bind the stacked sheets together.  
         [0035]     The invention is now described, by way of example, with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]      FIG. 1  is a schematic illustration showing an adhesive being applied to a sheet of print medium, in accordance with a method of the invention.  
         [0037]      FIG. 2  is a schematic illustration of a sheet with an adhesive strip positioned adjacent one edge of the sheet, as a result of the working of a method in accordance with the invention.  
         [0038]      FIG. 3  is a table schematically illustrating the principles of five alternative embodiments of the method of the invention.  
         [0039]      FIG. 4  is a schematic view of a number of sheets with all but the top sheet having a strip of adhesive applied to an upper surface adjacent to an edge to be bound.  
         [0040]      FIG. 5  is a schematic view of a stack of sheets with all but the bottom sheet having a strip of adhesive applied to a lower surface thereof adjacent to an edge to be bound.  
         [0041]      FIG. 6  is a schematic view of a stack of sheets with a first part of a two-part adhesive applied to the upper surface of all but the top sheet and a second part of a two-part adhesive applied to the bottom surface of all but the bottom sheet, in accordance with a method of the invention.  
         [0042]      FIG. 7  is a schematic perspective view of a support tray situated immediately down-line of the adhesive applicator, and used in a method of the invention.  
         [0043]      FIG. 8  is a schematic cross-sectional view of the support tray of  FIG. 7  showing a first sheet having a strip of adhesive adjacent its edge at an upper surface in an initial path of travel towards the support tray.  
         [0044]      FIG. 9  is a schematic cross-sectional view of the support tray and sheet of  FIG. 8 , with the sheet in an intermediate path of travel towards the support tray.  
         [0045]      FIG. 10  is a schematic cross-sectional view of the support tray and sheet of  FIGS. 8 and 9 , with the sheet at rest on the tray.  
         [0046]      FIGS. 11, 12  and  13  are schematic cross-sectional views of the support tray showing a second sheet in a path of travel towards the first sheet.  
         [0047]      FIG. 14  is a schematic cross-sectional view of the support tray having a number of sheets resting on the support tray, with all but the top sheet having an upwardly facing strip of adhesive adjacent an edge thereof.  
         [0048]      FIG. 15  is a schematic cross-sectional view of the support tray with a binding press in a path of travel towards an edge of the stacked sheets.  
         [0049]      FIG. 16  is a schematic cross-sectional view of the support tray with sheets bound by application of the binding press.  
         [0050]      FIG. 17  is a cross-sectional view of the support tray having a number of individual documents resting on the support tray, prior to the binding press being applied to a top document.  
         [0051]      FIG. 18  is a schematic cross-sectional view of the support tray and documents of  FIG. 17 , with all documents having been pressed, one upon another.  
         [0052]      FIG. 19  is a schematic perspective illustration of a number of documents bound in accordance with the method of the invention.  
         [0053]      FIG. 20  is schematic view of a support tray incorporating a different binding press to that shown in the preceding drawings, to be used in accordance with the method of the invention.  
         [0054]      FIGS. 21 and 22  are schematic perspective views of a portion of the binding press of  FIG. 20 .  
         [0055]      FIG. 23  is a schematic view of a support tray having an alternative press at a trailing edge of a stack of sheets to be bound. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0056]     In  FIG. 1 , reference numeral  10  generally indicates a process, in accordance with the invention, by which adhesive is applied to a sheet  11  as the sheet  11  passes through a printer incorporating an adhesive applicator.  
         [0057]     A driving station D drives the sheet  11  in the direction of an arrow  32 . The driving station D comprises a pair of opposed pinch rollers  12 . The sheet  11  is driven through a printing station P and then an adhesive application station A. Alternatively, the adhesive application station A precedes the printing station P. However, it is preferred that the adhesive application station A follow the printing station P so that adhesive on the sheet  11  does not clog a print head or print heads of the printing station P.  
         [0058]     For single sided sheet printing, the printing station P comprises a single print head  13 . The print head  13  is a pagewidth drop-on-demand ink jet print head. Alternatively, the print head  13  is that of a laser printer or other printing device. If the sheet  11  is to be printed on both sides, a pair of opposed print heads  13  are provided.  
         [0059]     It will be appreciated that in an embodiment where the print heads  13  are ink jet print heads, wet ink  15  on the sheet  11  could pass through the adhesive application station A. This could result in smudging and distortion of the print on the sheet  11 .  
         [0060]     Thus, the printer incorporates an air cushion application means that is configured to be positioned on either side of the sheet  11  as it passes through the printing station P. The print head  13  defines an airflow path or gap  14  through which air can pass to generate the air cushion. It will be appreciated that the air serves to dry the ink.  
         [0061]     The adhesive application station A can comprise an adhesive applicator  16  at one or both sides of the sheet  11 , depending upon which side or sides of the sheet to which adhesive is to be applied.  
         [0062]     As shown in  FIG. 2 , the sheet  11  having matter printed thereon by printing station P also includes a strip  17  of adhesive applied at the adhesive application station A.  
         [0063]     The strip  17  is positioned adjacent to a leading edge  27  of sheet  11 . The application of strip  17  adjacent to the leading edge  27  is suitable for those situations where the adhesive applicator does not touch the sheet  11 , or touches the sheet  11  at a velocity accurately matching that of the sheet  11  as it passes the adhesive application station A. Alternatively, the strip  17  is applied adjacent to a trailing edge  28  of the sheet  11 . This is more suited to adhesive applicators that make physical contact, such as brushing, with the sheet  11  as it passes the adhesive application station A.  
         [0064]     A margin  29  between the strip  17  and edge  27  or  28  of sheet  11  is 1 to 2.5 mm wide.  
         [0065]     Various methods of applying adhesive to the sheet  11  are envisaged, some of which are schematically depicted in  FIG. 3 .  
         [0066]     Method 1 in  FIG. 3  is a non-contact method of applying adhesive to the moving sheet  11 . In this method, a stationary adhesive applicator  16  sprays adhesive on to one side of the sheet  11  as it passes the adhesive applicator  16 . The adhesive applicator  16  is formed integrally with the print head  13 . Instead, the adhesive applicator is located upstream or downstream with respect to the print head  13 .  
         [0067]     Method 2 also applies adhesive to one side of the moving sheet  11 . However, in this method, an adhesive applicator  16 . 1  touches the sheet  11  while applying the adhesive. The adhesive applicator  16 . 1  is pivotally mounted about a fixed pivot point and is pivoted so that a tangential speed of the applicator matches a speed at which the sheet  11  passes through the adhesive application station A. A reaction roller  30  bears against an underside of the sheet  11  as the adhesive applicator  16 . 1  applies adhesive to the sheet  11 .  
         [0068]     Method 3 applies adhesive to both sides of the sheet  11  as it passes through the adhesive application station A. A pair of opposed, pivotally mounted adhesive applicators  16 . 2  are pivoted so that a tangential speed of the applicators matches a speed at which the sheet  11  passes through the adhesive application station A. Thus, the applicators  16 . 2  both touch the sheet  11  simultaneously and mutually counteract each other&#39;s force component normal to the sheet  11 .  
         [0069]     Method 4 employs a pair of adhesive applicator rollers  16 . 3  spaced from either side of the sheet  11  until activated to apply adhesive. At that point, the rollers  16 . 3  move toward and touch the sheet  11 , leaving the strip of adhesive  17  at either side of the sheet  11 . The rollers  16 . 3  mutually counteract each other&#39;s force component normal to sheet  11 .  
         [0070]     Method 5 employs a pair of adhesive spray applicators  16 . 4  positioned on each side of the sheet  11 . The applicators  16 . 4  do not touch the sheet  11 . Each applicator  16 . 4  applies one part of a two-part adhesive to a respective side of the sheet  11  so as to apply strips  17   a  and  17   b.  Like Method 1, Method 5 employs an adhesive applicator formed integrally with the print head  13 . A channel for the flow of one part of a two-part adhesive is provided in each print head  13 .  
         [0071]     The use of a two-part adhesive is beneficial in situations where there might be some delay in the printing/binding operation. The reason for this is that the two part adhesive requires mixing in order for setting to occur. Thus, if there were a computer software or hardware malfunction partway through a printing/binding operation, the use of a two-part adhesive could provide sufficient time within which to rectify the problem and complete the binding process.  
         [0072]      FIG. 4  illustrates a stack of sheets  11  with all but the top sheet provided with an adhesive strip  17  at an upper surface adjacent one edge to be bound.  
         [0073]     An alternative is depicted in  FIG. 5  wherein all but the bottom sheet has an adhesive strip  17  applied to its bottom surface adjacent an edge to be bound.  
         [0074]     In  FIG. 6 , a stack of sheets is shown with a part  17 A of a two-part adhesive applied to the upper surface of all but the top sheet  11  and a second part  17 B of the two-part adhesive applied to the bottom surface of all but the bottom sheet  11 .  
         [0075]     When the stacks of sheets of  FIGS. 4 and 5  are pressed together, adhesion of the sheets occurs as a result of mixing of the parts  17 A and  17 B.  
         [0076]     When the sheets  11  of  FIG. 6  are pressed together, the respective parts of the two-part adhesive in strips  17 A and  17 B combine so as to react and set.  
         [0077]     In an embodiment where the print head  13  is an ink jet print head, and non-contact adhesive application Methods 1 and 5 are employed, the adhesive strip  17  is applied to sheet  11  before ink on the sheet  11  passing through the adhesive application station  10  has dried. Air passing through the air gap  14  accelerates the drying process. Adhesive is applied to the sheet  11  as it passes out of the print head  13 . The air passing through the gap  14  facilitates a relatively high velocity of the sheet  11 , even though the adhesive strip  17  is applied to the sheet  11 .  
         [0078]     When the strip  17  is applied alongside the leading edge  27  of the sheet  11 , any alteration to the velocity of sheet  11  would adversely affect print quality. Hence, application of the adhesive strip  17  alongside the leading edge  27  is carried out using non-contact adhesive application methods or methods where the velocity of the adhesive applicator touching the sheet  11  is substantially the same as that of the sheet  11 .  
         [0079]     When the adhesive strip  17  is applied alongside the trailing edge  28  of the sheet  11 , the same situation is also desirable. For example, if the speed of the adhesive applicator of Methods 2 to 4 was faster than that at which the sheet  11  was passing the print head  13 , the sheet  11  could buckle.  
         [0080]     A particular embodiment of the present invention incorporates the use of a two-part adhesive. Further, in this embodiment, the adhesive applicators are positioned within the print heads  13  themselves. Thus, the print head  13  defines at least one passage for the flow of adhesive through the print head  13 . The advantage of this embodiment is that it would provide space and cost saving benefits.  
         [0081]     The likelihood of adhesive “gumming” and blocking such channels is diminished where a two-part adhesive is used. This is achieved by having only one part of the two-part adhesive passing through any particular channel or channels of the print head  13 .  
         [0082]     Where respective parts of a two-part adhesive are applied to opposed sides of the sheets  11 , those respective parts pass through dedicated channels in the respective print heads  13  on either side of the sheet  11 . This greatly reduces the likelihood of adhesive blockages in the flow channels.  
         [0083]     The adhesive or respective parts of a two-part adhesive can be provided in a chamber of a replaceable ink cartridge providing ink to the print head.  
         [0084]     The print head  13  is positioned proximate the pinch rollers  12 . The reason for this is that the rollers  12  provide a mechanical constraint upon the sheet  11  to enable accurate printing.  
         [0085]     The pinch rollers  12 , print heads  13  and adhesive applicator  16  are illustrated in  FIG. 7  alongside a sheet support tray  18 . Thus, the sheet support tray  18  receives sheets  11  once the adhesive strips  17  have been applied to the sheets  11 . The tray  18  is suspended from a frame  21  with respective dampers  22  at each corner of the tray  18 . The dampers  22  are elastomeric dampers or small hydraulic or pneumatic cylinders. The floor of the tray  11  has a lower-most corner  23  beneath which a vibrator  19  is positioned. The vibrator  19  is a subsonic vibrator (i.e. a vibrator having a frequency below 20 hz) or an out-of-balance electric motor.  
         [0086]     A binding press  20  is situated above the tray  18  over aligned leading edges of the sheets  11 , in use. Alternatively, the binding press  20  is positioned over the trailing edge  28  of the sheets  11 .  
         [0087]     In  FIG. 8 , a first sheet  11  is shown moving towards the tray  18 . The sheet  11  has a strip of adhesive  17  on its upper surface adjacent the leading edge  27 . It will be appreciated that the sheet  11  catches a pocket of air beneath it as it moves into position. This facilitates such movement by reducing friction substantially. The leading edge  28  then strikes a wall  31  of the support tray  18  as shown in  FIG. 9 . The vibrations of the tray  18  caused by the vibrator  19  results in the sheet  11  coming to rest with the leading edge  27  positioned adjacent the corner  23  of the tray  18  as shown in  FIG. 10 . Eventually, the leading edges  27  of the sheets  11  bear against the wall  31  of the tray  18  as shown in the drawings.  
         [0088]     In  FIG. 11 , a second sheet  11  is shown moving towards the tray  18 . The second sheet  11  comes to rest upon the first sheet  11  in a position aligned with the first sheet  11  as depicted in  FIG. 13 .  
         [0089]     If the sheets  11  have the adhesive strip  17  applied to the upper surface, the final sheet  11  is provided without any adhesive and it comes to rest at the top of the stack as depicted in  FIG. 14 . If, instead, the majority of sheets  11  had the adhesive strip  17  applied to their bottom surface, the first sheet  11  (i.e. the sheet at the bottom of the stack) would have no adhesive applied to it. This would be suitable for multiple binding compressions.  
         [0090]     As shown in  FIG. 15 , the binding press  20  is driven downwardly towards the stack of sheets  11  over the aligned adhesive strips  17 . The stack is then compressed into a bound volume  24  as shown in  FIG. 16 .  
         [0091]     It should be noted that no subsequent edge trimming of the bound volume is required provided standard-sized sheets  11  are used. The reason for this is that the vibrator  19  aligns the sheets  11  into the lower-most corner  23  of the tray  18  as described earlier.  
         [0092]     In  FIGS. 17 and 18 , multiple volumes  24  are shown stacked one upon another with the upper-most volumes being progressively compressed by repeated applications of the press  20 .  
         [0093]     The binding press  20  is shown schematically in the Figures and could be pneumatically or hydraulically driven, or could be driven by other mechanical means such as rack and pinion, electrical solenoid or otherwise.  
         [0094]     One embodiment of the binding press  20  is depicted in  FIGS. 20, 21  and  22 . In this embodiment, the binding press  20  incorporates a plurality of semicircular disks  34  each spaced apart, but fixedly mounted to a common, rotatably driven shaft  36  extending along an axis of rotation  26 . Each disk  34  passes through a respective vertical slot  32  formed in the wall  31  of the tray  18 . In an initial condition, the disks  34  are in the orientation shown in  FIG. 21 . Upon rotation of the shaft  36 , the disks  34  pivot into a position shown in  FIGS. 20 and 22  to press down upon the sheets  11 .  
         [0095]     The tray  18  is provided with a floor of adjustable height so that a top sheet  11  can be positioned proximate the binding press  20 . This reduces noise levels by minimizing a stroke length of the binding press  20 .  
         [0096]     The floor of the tray  18  is driven to move downwardly as each sheet  11  is fed into the tray  18 . This ensures that the top sheet  11  remains at a constant level. This also minimizes the extent of necessary movement of the binding press  20 .  
         [0097]     In the embodiment in which the adhesive strips  17  are applied alongside the trailing edge  28 , the trailing edges  28  are pressed together with a pressing mechanism  38  provided in a position opposite the wall  31 .