Abstract:
A bookbinding machine binds a stack of pages along a first edge thereof to form a book using an adhesive having a melting temperature and an elongated resistive strip having an adhesive atop at least a portion of a first side. The strip has two opposed ends and an electrical resistivity between the ends and is dimensioned to substantially cover the first edge of the stack, with the first side against the first edge of the stack. An electrical current is introduced to pass along the strip between the ends. The current should be sufficient to create enough heat in the strip to achieve a temperature at least as great as the melting temperature, enabling the melted adhesive to bind the stack of pages together along the first edge. Apparatus are also provided for supporting, holding, and clamping the page stack prior to and during the binding process.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority from Provisional Patent Application 60/446,015, filed on Feb. 6, 2003, entitled “Bookbinding Machine and Method for Individual Bookbinding System.” 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to systems and methods for binding pages together, and, more particularly, to such systems and methods for binding individual books. 
   2. Description of Related Art 
   A variety of different techniques are known for binding books. At one end of the spectrum is the so-called perfect binding technique used for paperback books. Individual page sheets are bound directly to the inside of the spine of the cardboard cover using a hot-melt adhesive that is solid at room temperature. Perfect binding is suitable for paperback books produced in large quantities. The high-volume machines used for perfect binding are very large and costly and must be set up for each run of books, a time-consuming process that often results in making trial copies that must be discarded. High-volume perfect binding machines are not practical for running single copies of books such as those downloaded from the Internet. 
   Thermal tape is another means for binding books and is often employed as a finishing operation for high-volume xerographic duplicators. The pages are individual sheets, usually 8½×11 inches, and the covers are cardboard sheets of the same size as the pages. Paper tape coated on one side with hot-melt adhesive forms the spine of the book, and the adhesive is activated as it passes over heated surfaces inside the machine. There is no way to print the title and author&#39;s name on the spine unless pasted on in a separate label. While thermal tape is a convenient method for binding small lots of booklets such as college course packs, such booklets do not offer the aesthetic appeal of high-quality bound volumes. 
   There are various other means for binding small quantities of books using staples, plastic combs, wire spirals, and plastic posts, none of which provides the look and feel of a fine bound volume. 
   A preferred method for binding books is the traditional cloth binding technique used for hardcover books. The pages are printed on large sheets called signatures, which are then folded, sewed and glued together, and then trimmed. The cover consists of front and back cardboard pieces encased in decorative cloth binding material, which also forms the hinges and outer spine. Cloth binding has advantages of quality appearance, durability, and ease of page turning, since the pages are glued to a flexible inner cloth spine that is fastened to the outer spine only at its edges. Like perfect binding, cloth binding is a high-volume process involving the use of large and costly machines, and is therefore not suitable for binding single copies. There are a few craftsmen who specialize in custom binding or repairing single cloth bound books, but such work is highly skilled and expensive. 
   At the high end of the spectrum are leather-bound books. Produced by a process similar to cloth binding, leather-bound books offer the ultimate in luxurious appearance. 
   It is known in the art to heat a hot-melt adhesive onto page edges to bind a book with an external heater. It is also known to heat a hot-melt adhesive coated on an electrically resistive layer applied to the inner surface of a report binder with the use of a power supply. It is also known to use a microwave-activatable adhesive to bind books, with the adhesive placed between a sheaf of papers and the binder. Additionally, it is known to employ individual book-binding apparatus following the printing of a book from a storage medium such as a database. 
   Although there is widespread interest in methods for binding cut sheets from desktop computer printers into high-quality books, no commercially viable, easy-to-use device has been disclosed. 
   SUMMARY OF THE INVENTION 
   The present invention provides systems and methods for binding an individual book that has superior aesthetic qualities, can create a book with a plurality of cover types, including both hard covers and soft covers, and are easily adaptable to books of various sizes. Books made by the present systems and methods do not require trimming of the book or the binding strip upon completion of the binding process. 
   A method of the present invention is directed to binding a stack of pages to form a book. This method comprises the steps of placing a flyleaf inside a book cover, a spine of the flyleaf being affixed to a spine of the book cover, and placing an electrically resistive strip adjacent an inside of the flyleaf spine of a book cover. The strip has a hot-melt adhesive in contact therewith, for example, as a coating upon or impregnated into the strip. 
   A stack of pages desired to be bound is positioned inside the flyleaf, a binding edge of the page stack adjacent the strip, to form a book assembly. Pressure is applied to an outside of the flyleaf adjacent the strip and along the page stack binding edge, with the strip positioned between the flyleaf spine and a region of pressure application. 
   An electrical current is passed along the strip to create heat sufficient to melt the adhesive. The melted adhesive serves to bind together the binding edge of the page stack to the flyleaf spine and to affix a first and a last page of the page stack to the flyleaf adjacent the flyleaf spine. When the current is discontinued, the adhesive is permitted to solidify following the electrical current&#39;s being stopped and prior to removing the pressure. 
   The features that characterize the invention, both as to organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description used in conjunction with the accompanying drawings. It is to be expressly understood that the drawings are for the purpose of illustration and description and are not intended as a definition of the limits of the invention. These and other objects attained, and advantages offered, by the present invention will become more fully apparent as the description that now follows is read in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1A–1D  illustrate a first embodiment of elements and a method for binding hardcover books with superior aesthetics. 
       FIGS. 2A–2D  illustrate a second embodiment of elements and a method for binding hardcover books with superior aesthetics. 
       FIGS. 3A–3D  illustrate elements of the page stack alignment fixture and the method of using same. 
     FIGS.  4 A, 4 B is a top-side perspective view of exemplary removable clips for attaching clip leads from a power supply to the binding strip. 
       FIG. 5  is a view of an embodiment of the bookbinding machine. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A description of the preferred embodiments of the present invention will now be presented with reference to  FIGS. 1A–5 . 
   In the present invention, the term “book” may comprise any collection of individual sheets that are desired to be bound together, and should not be taken as a limitation. Preferably all the pages should be of substantially the same size. 
   The invention is contemplated for use in such applications as binding a stack of pages that have been collected together or printed from a source such a desktop computer printer, as a download from a remote location (e.g., a site on the Internet), or a storage medium such as a disk. However, this application is not intended as a limitation, and one of skill in the art will understand that the invention may be used in any binding situation. 
   The present invention is generally directed to the binding of books wherein electric current is used to melt adhesive positioned adjacent a page stack edge desired to be bound in a hot-melt binder. The hot-melt adhesive is supplied in solid form, precoated on or impregnated into an electrically resistive strip. In use, the width of the adhesive strip is first trimmed to the approximate thickness of the page stack of the book, such as by using ordinary office shears or a paper cutter. Similarly, the length of the strip is trimmed to the approximate length of the page stack. Alternatively, various precut widths and lengths of strips may be supplied to a consumer. 
   In the embodiment of the system  10  and method of the invention shown in  FIGS. 1A–1D , a cover assembly  80  is made by affixing a pair of liners  801 , 802  to an inside of front  803  and back  804  cover pieces, each liner  801 , 802  comprising a cover portion  803  and a spine portion  806  meeting at a fold  807 . The cover pieces  803 , 804  comprise substantially planar, substantially rigid rectangular elements suitable for making a hardcover book. The book assembly  80  further comprises a substantially planar, substantially rigid, typically rectangular spine  808 . 
   The cover assembly  80  is created by placing an inner edge  809  of each cover piece  803 , 804  adjacent respective lateral edges  810 , 811  of the spine  808 . The liners  801 , 802  are positioned so that their cover portions  805  are substantially parallel, with one of the spine portions  806  atop the other spine portion. A flexible covering  82  is affixed to an outside of the front  803  and the back  804  cover pieces and the spine  808  in covering relation to at least a seam region  83  where the spine&#39;s lateral edges  810 , 811  meet the respective inner edges  809  of the front  803  and the back  804  cover pieces. 
   A pair of flyleaf elements  814 , 815  each comprises a cover portion  816  and a spine portion  817  meeting at a fold  818 . The flyleaf elements  814 , 815  are positioned so that their cover portions  816  are substantially parallel, with one of the spine portions  817  atop the other spine portion. 
   An electrically resistive strip  11 , which has been coated or impregnated with a hot-melt adhesive  111 , is affixed using an adhesive, such as, but not intended to be limited to, a pressure-sensitive tape  12  that has been applied to a back  110  of the strip  11 , to the top flyleaf spine portion  817 . The resistive strip  11  may have been trimmed to a desired dimension commensurate with the dimensions of the binding edge  131  of a page stack  13  desired to be bound. Alternatively, the resistive strip  11  may be supplied precut to match the standard lengths of various books. Clip leads  14  are removably attached to each end of the strip  11  (FIGS.  4 A, 4 B). 
   The page stack  13  is positioned between the flyleaf elements  814 , 815  so as to rest on the resistive strip  11 , with the binding edge  131  adjacent the strip  11  ( FIG. 1B ). This step may be facilitated by using a page stack carrier  15  to surround at least a portion of a free edge  132  of the page stack  13 . The free edge  132  is opposed to the binding edge  131 . The page stack carrier  15  helps to retain an alignment of the pages during the binding process, and may comprise, as shown, a container dimensioned to receive the page stack. 
   In this embodiment, a pair of elongated, substantially cylindrical spacers  16  are placed between each of the flyleaf elements  814 , 815  and the respective book cover piece  803 , 804 , between the strip  11  and the page stack&#39;s free edge  132 , but fairly close to the strip  11 . 
   The front  803  and back  804  cover pieces are folded upward along the sides of the page stack  13 , and the book assembly  17  is placed into an adjustable-width substantially squared-U-shaped holder, such as, but not intended to be limited to, the bookbinding machine  18  shown in  FIG. 5  to maintain the position of the parts during the binding process. This particular machine  18  will be discussed in the following. 
   Pressure is first applied to an outside of the flyleaf elements  814 , 815  adjacent the strip  11  along the page stack&#39;s binding edge  131  sufficient to hold the book assembly  17  in position. A source of electrical current in contact with the leads  14  is activated, so that the flow of current for a predetermined time heats the resistive strip  11 , causing the adhesive  111  to melt. An exemplary binding voltage comprises approximately 5 volts rms to yield an exemplary binding current of approximately 5 amperes rms, and the predetermined time is typically 1–2 minutes. 
   During the heating cycle, the page stack  13  is pressed against the strip  11 , preferably applying a scrubbing motion to the page stack  13  for increasing contact between the binding edge  131  and the melted adhesive  111 . This method exposes all the pages to melted adhesive  111 , and forces melted adhesive  111  between the flyleaf portions&#39; folds  818  and onto the first and last pages of the page stack  13 . 
   At the conclusion of the heating cycle, the current is turned off, the clip leads  14  are removed, and the page stack  13  is pressed downward toward the spine  808  to fill any spaces previously occupied by the clip leads  14 . Additional clamping pressure is then applied to a pressure-application region outside the cover pieces  803 , 804  and adjacent the spacers  16 , so that a region of the flyleaf covers  816  adjacent the flyleaf portions&#39; folds  818  is glued to the first and last pages of the page stack  13 . This technique hides an unsightly gutter between the page stack  13  and the cover  80 . 
   The assembled book is then left in the holder  18  for several minutes while the adhesive  111  completely solidifies, typically for a period of approximately 10 minutes. The page stack carrier  15  is also removed. Following solidification, the clamping pressure is released, and the completed book is removed from the bookbinding machine  18 . 
   In a second embodiment  30  of the invention ( FIGS. 2A–3D ), a cover assembly  31  is created substantially as for the first embodiment  10 . Here, however, the liner  32  and the flyleaf  33  are each unitary elements. The liner comprises a single sheet folded to form a spine portion  321  and two cover portions  322  meeting at folds  323 . The flyleaf  33  comprises a single sheet folded to form a spine portion  331  and two cover portions  332  meeting at folds  333 , with an additional inward fold  334  that partially covers the strip&#39;s lateral edges  112 . The inward folds  333 , 334  may be prescored. 
   Another feature of this embodiment  30 , which could also be used with the first embodiment  10 , includes a page stack alignment device (FIGS.  3 A, 3 B)  40  for use in maintaining page alignment and also provides a feature for defining a pressure application region. The alignment device  40  comprises a pair of alignment elements  41 , 42 . Each alignment element  41 , 42  has a pair of substantially rigid and substantially planar support elements  411 , 421 , each support element having a first  412 , 422  and a second  413 , 423  cover guide extending along an outside of at least a portion of a first  414 , 424  and an opposed second  415 , 425  edge of the support element  411 , 421 , respectively. The first  412 , 422  and the second  413 , 423  cover guides are separated by at least a height  819  of the book cover  80 , at least one of the support elements  411 , 421  (here, the first  411 ) further having a first  416  and a second  417  page stack guide extending along an inside of at least a portion of the first  414  and the second  415  support element edges, respectively. The first  416  and the second  417  page stack guides are separated by at least a height  134  of the page stack  13 . A flexible tape  419  may be used to connect the first  411  and the second  421  support elements together adjacent at least one of the pairs of edges  414 , 424 ; 415 , 425  for ease of handling. 
   In this embodiment  30 , the page stack carrier  15  is placed over the free edge  132  as above, and the alignment device  40  is positioned to straddle the page stack carrier  15  and the flyleaf cover portions  816 . The page stack  13  is positioned between the support elements  411 , 421  as shown in  FIGS. 3B–3D , the top  135  and bottom  136  edges of the page stack  13  in bounding relation to the first  416  and a second  417  page stack guides. The alignment device  40  is then slid downward so that the lower edges  418 , 428  of the support elements  411 , 421  reach the inward folds  334  of the flyleaf  33  until the top parts of the inward folds  334  cover the strip&#39;s lateral edges  112 . The top and bottom edges of the cover  80  are bounded by the first  412 , 422  and a second  413 , 423  cover guides. Using the alignment device  41 , the page stack  13  can be positioned within the cover  80 , the page stack  13  centered along the midline of the strip  11 , and midway between the top  821  and bottom  820  edges of the cover  80 . 
   The steps of clamping the jaws of the bookbinding machine sufficiently to hold the book assembly  43  in position, applying electrical current along the strip  11  to melt the adhesive  111 , turning off the current, pressing on the page stack  13  to expose the pages to melted adhesive  111 , removing the clip leads  14 , and pressing the page stack  13  downward are substantially as above. The alignment device  40  is used to press the flyleaf&#39;s inward folds  334  into the melted adhesive  111  ( FIG. 3C ). The additional clamping pressure is then applied in the region of the inward folds  334 . The cooling, solidifying, unclamping, and book-removal steps are substantially as above. 
   This system and method offer several advantages: 
   Pre-scored sections of the flyleaf  33  adjacent the strip  11  can be folded down and glued in place at the time of binding to cover the unsightly gap in the gutter between the page stack  13  and the inner surface of the cover  80 . 
   By prescoring a series of parallel folds in the flyleaves, a single cover size and resistive strip  11  can accommodate a wide range of page stack thicknesses (e.g., from ⅛th to ½ inch). This would be desirable for creating digital photo albums, for example, which might contain from 10 to 50 pages. (Each page of inkjet photo paper is about 10 mils thick.) The thickness of the cover portions  803 , 804  can be chosen to provide the most pleasing aesthetics for the book, with covers neither excessively pinched in nor bulging out relative to the spine width over the expected range of page stack thicknesses. 
   Maintaining a minimum cover spine width of at least ½ inch is desirable to accommodate lettering on the spine, for example a book title in hot-stamped gold letters. This construction permits the spine width to be maintained at ½ inch even with thin page stacks (e.g., ⅛th inch). 
   The hinges of the cover are mechanically isolated from the binding of the page stack, so that the cover opens easily without creating stress in the page stack binding that might cause the binding to split. 
   A page stack alignment fixture  40  fabricated from hardboard, plastic, wood, or similar material ( FIG. 3A ) is designed with guides to center the page stack along the midline of the resistive strip  11  and midway between the top and bottom edges of the cover. It also provides a means to press the folded bottoms of the flyleaves against the melted adhesive at the conclusion of the heating cycle to cover the unsightly gutter. 
   A method for binding a paperback book is similar, although some steps preferred for binding hardcover books are omitted: Using the small pads of pressure-sensitive tape  12  that are supplied on the back of the binding strip  11 , tack the binding strip  11  to the inside spine  806  of the empty book cover  80  ( FIG. 1B ). Attach removable clips  14  to the ends of the resistive strip  11  ( FIG. 4B ). Place the empty cover  80  between the jaws of the bookbinding machine  18  and attach the clip leads  14  to the strip  11 . Insert the page stack  13  into a page stack carrier  15  (see  FIG. 1B ) and place it in position within the cover  80 . Clamp the jaws of the bookbinding machine  18  just enough to hold the cover  80  and page stack  13  in position. Switch on the power and adjust the current control. After 1–2 minutes of heating, press down on the page stack carrier  15  with a scrubbing motion to expose all the pages to the melted adhesive  111 . Switch the power off, immediately pull out the clip leads  14 , and press down firmly on the page stack carrier  15  to fill any spaces previously occupied by the clip leads. Check alignment of all parts and clamp firmly; allow the bound book to cool for 10 minutes so that the adhesive  111  can completely solidify. 
   An exemplary embodiment of the bookbinding machine  18  of the present invention is illustrated in  FIG. 5 . A low-voltage power supply  181  is surmounted by a rigid binding platform  182 . To avoid short circuits if accidentally touched by the clip leads  14  during the binding cycle, the platform  182  is made of a nonconducting material such as wood or plastic, the jaws  183  that clamp the book during the binding cycle have insulating coatings, and the clip leads  14  are insulated except for the tips. The binding platform  182  extends beyond the lateral extent of the power supply  181 , facilitating carrying the device  18 . 
   In an exemplary embodiment, the stationary and adjustable jaws  183  are 14 in. long, so that it is possible to bind books from pocketsize to coffee table-size, having spine lengths ranging from 2 to 14 in. The space between the jaws  183  can be adjusted by means of a knob  184  and lead screw  185  to accommodate books up to 2 in. thick. 
   The insulated clip leads  14  provide flexibility to connect the power supply  181  to the resistive binding strip  11  of books of any size in the range of spine lengths and thickness specified above. 
   The front-mounted control panel contains a power switch  187  that is illuminated when the power is on, a knob  188  for adjusting the binding current, and a meter  189  for measuring the binding current to set the optimal binding current for books of various sizes. Experiments have shown that it is important to control the binding current. If the current is too low, the melted adhesive will not achieve and hold the low viscosity (typically less than 5000 centipoise) necessary to soak up into the edges of the page stack  13  to ensure optimal binding strength. If the current is too high, the spine  801  of the cover  80  may be scorched. Since the power dissipated in the binding strip  11  is proportional to the square of the current, accurate control of the current is very important. 
   The solid-state power supply  181  provides a low-voltage pulse-width-modulated ac binding voltage to minimize contact resistance losses that would be excessive if, for example, variable-voltage dc were to be used. For safety, the binding voltage is typically about 5 volts rms and the binding current is typically about 5 amperes rms. The design of the power supply circuitry is straightforward for someone skilled in the art of electronic power supplies. If desired, a binding cycle timer (not shown) to switch off the power at the end of the binding cycle could be added. 
   In the foregoing description, certain terms have been used for brevity, clarity, and understanding, but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such words are used for description purposes herein and are intended to be broadly construed. Moreover, the embodiments of the apparatus illustrated and described herein are by way of example, and the scope of the invention is not limited to the exact details of construction.