Abstract:
A trimmer for trimming a book has a support for supporting a book, at least one laser for scoring an edge of the book so as to produce a score, and a trimming station for trimming the book at the score.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Priority to U.S. Provisional Application No. 60/440,275, filed Jan. 15, 2003 and hereby incorporated by reference herein, is claimed. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to printed materials and more particularly to trimming units for trimming edges of a book. 
     U.S. application No. 2002/0034428 discloses a trimmer for trimming excess margins along one, two or three edges of a perfect bound book. The book is gripped by a book holder, and a shearing blade cuts the edges of the book. The shearing blade has a flat edge and reciprocates. 
     European Patent Application No. 1 201 379 discloses a three-sided trimmer having a top edge cutting knife, a bottom edge cutting knife and a fore edge cutting knife, all with flat edges and reciprocating. 
     European Patent Application No. 0 893 277 discloses a trimmer, particularly for trimming book backs. A milling cutter has a disc-shaped body specially shaped teeth. The trimmer is a rotary cutter. 
     A problem associated with prior art trimmers used for trimming books is the delamination of the cover of a book from the interior sheet material, or the tearing of the book material. This trim defect is typically called “chipout” or “tearout”. 
     It has been known to score the spine of the book with scoring knives before the head and foot of the book are trimmed. 
     SUMMARY OF THE INVENTION 
     Co-pending U.S. application Ser. No. 10/208,551 of the present assignee, filed Jul. 20, 2002 and hereby incorporated by reference herein, discloses a trimming blade for minimizing chipout. 
     Mechanical scoring knives face issues such as blade wear, cycling times and problems scoring shapes. 
     An object of the present invention is to improve the trimming of books, especially of the sides of books adjacent to the spine. Another alternate or additional object of the present invention is to reduce chipout. Yet another alternate or additional object of the present invention is to improve scoring speed and/or provide for scoring of irregularly shaped spines and/or improve wear characteristics of a scoring device. 
     The present invention provides a trimmer for trimming a book comprising:
         a support for supporting a book;   at least one laser for scoring an edge of the book so as to produce a score; and   a trimming station for trimming the book at the score.       

     By using a laser to produce a score, chipout may be minimized. Scoring speed and scoring device wear can be improved. Irregularly shaped edges can be scored. 
     Preferably, the edge is a spine of the book. The laser may score, for example, an outer layer of cover material at the spine or through the entire spine. 
     The support preferably is a conveyor and the at least one laser is stationary. 
     Advantageously, two lasers may be used to score the edge at the head and the foot of the book, although one laser also may be used. A single laser with a beam splitter may also be used. 
     The laser beam of the laser preferably contacts the edge at an acute angle, although other angles may be used. 
     The trimmer may be a three-edge trimmer, with a face trimming station and with a head and foot trimming station as the trimming station for trimming at the score. Preferably, the laser scoring device scores the spine just upstream of the head and foot station. For example, in certain trimmers the laser scoring device may be downstream from the face trimming station, so that the action of the face trimming station does not alter the score location for the head and foot station. 
     The present invention also provides a method for trimming a book comprising the steps of scoring an edge of the book using a laser so as to create a score, and trimming the book at the score. 
     Also provided is a laser scoring station comprising a support for supporting a book and at least one laser for scoring an edge of the book so as to produce a score. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows one embodiment of the trimmer of the present invention using two lasers. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an embodiment of a trimmer for books  30 A,  30 B,  30 C,  30 D moving in a direction  22 . The books have their spines facing forward, so that for example spine  32 A of book  30 A faces in the direction of travel. A first conveyor  12  moves book  30 A to a face trimming station  10  having a reciprocating blade  14  for trimming the face of the book  30 A. Retractable stops  21  may stop the spine  32 A to position the face for trimming. The face is opposite spine  32 A. Book  30 A may be clamped in face trimming station  10  during the face trimming operation. 
     The stops may then be retracted and the books are then transferred, for example by conveyor  12 , to conveyor  20 , which may have a lower and top belt to transport the books. At a spine scoring location  18 , book  30 B may be scored by lasers  40 ,  42  at both a head location  34  and a foot location  36 . Lasers  40 ,  42  thus are located at the sides of the conveyor  20 , and supported by a frame  50 . Lasers  40 ,  42  may be adjustable with respect to the frame  50  for minor adjustments of the score position, but are fixed during operation. Lasers  40 ,  42  may score the spine at an angle A, which may be for example 45 degrees. 
     A controller  70  may have an input identifying the position and speed of the products on conveyor  20 , and control the pulsing of the lasers  70 ,  72  so that the laser beams of the lasers  70 ,  72  score the laser for an appropriate amount of time at an appropriate power. A thickness of the book can also be input into controller  70 . The score preferably cuts through the spine, for example the glued section of the spine. Angle A preferably is an acute angle. 
     Scored book  30 C passes by the lasers  40 ,  42  to a head and foot trimming station  60 , where a reciprocating head trimming blade  64  trims the head of book  30 D at a score location equivalent to score  34  and a reciprocating foot blade  62  trims the foot of the book  30 D at a score location equivalent to score  36  of book  30 B. The book  30 D may be clamped during the trimming operation of station  60 . 
     The laser scoring reduces chipout caused by the blades  62 ,  64 . The laser scoring reduces scoring blade wear, and permits for faster scoring. 
     For many applications, the lasers  70 ,  72  may be for example RF excited CO2 lasers from the firm Coherent, Inc. operating at a wavelength of 10.6 micrometers and having a power of 30 watts. Appropriate scores using such lasers for certain trimmers for book thicknesses up to 1 inch may result for example at conveyor speeds of about 50 meters per second and pulse times of about 0.3 seconds. However, other types of lasers may be used. 
     The present invention is not limited to any specific speeds, laser types, laser powers, pulse durations, trimmer blade types, trimmer types or book thicknesses, and the appropriate combination of such attributes may be determined as required by the specific application. For example, such attributes may be determined for a particular trimmer by viewing finished books for chipout, and altering one or more attribute to reduce chipout if chipout has occurred. Such attributes also may change depending on a type of glue used for the spine, for example. The attributes may also be changed upon a review by an operator of the scoring depth of the score. For example, if the score appears to be too shallow, the pulse duration or laser power may be increased. 
     While a specific trimmer has been disclosed, the trimmer may be of any type, including a single station trimmer that does not convey the book. 
     “Book” as defined herein may be any collection of sheet material with a spine.