Abstract:
An improved rotary UV curing method and apparatus is provided to more effectively polymerize and cure an UV curable product, article, ink coating or adhesive in or on a disk. Advantageously, the improved rotary UV curing method and apparatus has a special arrangement that provides for rotational movement between an array of UV-LED chips mounted on a panel and a UV curable disk or other UV curable product, article, ink, such as a UV curable coating or adhesive, to better cure the UV photo initiators disk and product. One or more shields can also be provided to protect the UV LED chips from splatter or other objects which could otherwise damage or decrease the light emission, intensity and effectiveness of the UV LED chips.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of U.S. application Ser. No. 10/753,837 filed Jan. 7 2004, which is a continuation-in-part of U.S. application Ser. No. 10/386,980 filed Mar. 12, 2003, which is a continuation-in-part of U.S. application Ser. No. 10/339,264 filed Jan. 9, 2003, all of which are incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention. 
         [0003]    The present invention relates to a method and apparatus for utilizing ultraviolet (UV) light to cure a disk-shaped product using UV-LED chips mounted in an array and providing for relative movement between the array and the disk-shaped product, thereby to cure a curable ink, coating or adhesive mounted in the disk-shaped product. The inks, coatings and adhesives have UV photo initiators which, when exposed to UV light, convert monomers in the inks, coatings and adhesives to linking polymers to solidify the curable material. 
         [0004]    2. Description of the Related Art. 
         [0005]    Heretofore, UV-LED arrays have been proposed for curing inks, coatings or adhesives. 
         [0006]    The prior proposals teach one to stagger rows of UV-LED&#39;s in different arrays on a panel positioned closely adjacent a product to be cured, to move the product past the array, to move the array in a generally orbital path to uniformly apply UV light on the product and to inject an inert, heavier than air or lighter than air gas in the area between the panel and the product. 
         [0007]    Also it has been learned that different wavelengths of UV light are better suited for different thicknesses of ink, coating or adhesive and/or for different components in the ink coating or adhesive. 
         [0008]    For example, thick polymers require longer wavelengths for curing. Surface curing requires shorter wavelengths. 
         [0009]    Further, a common use of UV curable adhesives and coatings is in the manufacture of compact disks, CD&#39;s. 
         [0010]    It is, therefore, desirable to provide an improved UV method and apparatus for applying UV light at one or more wavelengths to a disk-shaped UV curable product to more effectively cure UV inks, coatings and adhesives in or on the product, by causing relative rotation between the UV light and the disk-shaped product. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    According to the present invention, there is provided a method and apparatus for curing an UV curable product, article, ink coating or adhesive in or on a disk including the step of or mechanisms for causing relative rotational movement between an array of UV-LED chips mounted on a panel and a disk containing the UV curable product, article, ink coating or adhesive. 
         [0012]    Also, according to the present invention there is provided at least one staggered array of UV LED assemblies on at least one panel with the UV LED assemblies being arranged in rows with each row being staggered from adjacent rows. A mechanism is provided for causing relative rotational movement between the panel and a disk-shaped product. 
         [0013]    In one preferred embodiment, the disk-shaped product containing the UV curable product, article or other object to be cured is arranged to rotate. A gas having a molecular weight heavier than air or lighter than air can be injected into the area of rotation of the UV curable product, article or other object having a UV ink, coating, or adhesive thereon as it rotates past a panel of arrays of UV LED assemblies. 
         [0014]    In another preferred embodiment, the panel or a + shaped (cross-shaped) structure comprising four panels is caused to rotate relative to the disk-shaped product. 
         [0015]    Advantageously, the method and apparatus of the present invention provide better uniformity of light application from a flat panel having an array of UV-LED&#39;s. This result can be obtained when the product and/or the light fixture is rotated relative to and across the UV light beams from the UV-LED assemblies. The rotational movement has the ability to provide enhanced uniformity. Desirably, the rotation of the UV curable product or the rotation of the light array provides outstanding uniformity of UV light and UV curing of the product. 
         [0016]    A more detailed explanation of the invention is provided in the following detailed description and claims taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a top plan view of a panel or substrate mounting an array of UV-LED chips positioned above a disk-shaped product, which is caused to rotate underneath the array; 
           [0018]      FIG. 2  is a vertical sectional view through the disk and panel or substrate shown in  FIG. 1  and also shows a dispensing apparatus for dispensing liquid having a UV photo initiator therein onto the disk-shaped product as it rotates under the dispensing apparatus; 
           [0019]      FIG. 3  is a top plan view of a + shaped (cross-shaped) arrangement of four panels each having an array of UV-LED chips mounted thereon for rotation above a disk; and 
           [0020]      FIG. 4  is a vertical, partially sectional view of the cross-shaped panel assembly shown in  FIG. 3  and shows a glass or plastic shield between the UV-LED chips in the four arrays and the disk therebeneath and also shows an auxiliary array of UV-LED chips on the side of the disk and a glass or plastic protecting shield between the auxiliary array and the side of the disk. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    A detailed description of the preferred embodiments and best modes for practicing the invention are described herein. 
         [0022]    Referring now to  FIG. 1 , there is illustrated therein a generally rectangular-shaped, horizontal, substantially planar or flat, fixed panel  10  mounting an array  12  of staggered, offset UV-LED chips  14 . The UV-LED chips  14  are arranged in staggered rows and mounted to the panel  10  such that the UV-LED chips  14  in one row are adjacent spaces between UV-LED chips  14  in an adjacent row. It will be understood that the array  12  shown on the upper side of the panel  10  is for the convenience of showing the array  12  and that actually, the array  12  of UV-LED chips  14  are mounted on the underside of the panel  10 . The array  12  of UV-LED chips  14  is better shown in  FIG. 2 . The panel  10  can be supported by an upright vertically disposed support structure in the form of a cantilevered base  15  ( FIG. 2 ), so that the panel  10  can be positioned over a generally disk-shaped product  16 , or, simply a disk  16 . The arrow  18  in  FIG. 1  indicates the direction of rotation of the disk  16  in a UV-LED chip apparatus  20  including the panel  10  for curing UV photo initiators on or in the disk  16 . 
         [0023]    As shown in  FIG. 2 , the apparatus  20  can include a support pad  22  for supporting the disk  16 . The support pad  22  can be fixed to an output shaft  24  at one end of a motor  26 . The motor  26  can be energized periodically to rotate a disk  16  placed on the support pad  22  to enable UV light from the UV-LED chip array  12  to cure an UV curable product, article, ink coating or adhesive in or on the disk  16 . Between the array  12  of UV-LED chips  14  and the disk  16  there can be positioned a glass or plastic sheet or plate  28  for protecting the UV-LED chips in the array  12  from splatter. 
         [0024]    The UV-LED chips  14  are preferably arranged in an offset staggered array  12  on at least one panel  10 . If desired, at least one row of UV LED chips  14  can emit light in the visible light spectrum whereby a user can visually determine that power is being supplied to the array  12  of UV LED chips  14 . 
         [0025]    Further, a heavier than air or lighter than air, non-oxygen, non-combustion supporting gas can be provided in the area between the panel and the product to enhance UV curing. Also, the gas can be circulated by a fan to enhance cooling of the UV-LED chips  14  and heat dissipating fins can be mounted on the top side of panel  10  to further enhance cooling of the UV-LED chips  14 . 
         [0026]    Also shown in  FIG. 2 , is a dispenser  30  for dispensing a liquid  38  having one or more UV photo initiators therein onto the upper surface of the rotating disk  16 . The dispenser  30  is preferably positioned above the disk  16  and can have a dispensing point  34  near the center of the disk  16  so that liquid  38  dispensed can flow by centrifugal force radially outwardly to a periphery of the disk  16  as the disk  16  rotates. At the same time, the UV curable liquid coated portion of the disk  16  passing beneath the array  12  of UV-LED chips can be cured, polymerized and solidified, by the UV light emitted from the UV-LED chips  14 . 
         [0027]    In  FIG. 3 , there is illustrated another UV-LED chip apparatus  40  for curing UV photo initiators in or on a stationary or fixed disk  16 . As shown, the apparatus  40  includes a cross-shaped or + shaped structure  42  including four rotatable, generally horizontal, substantially flat or planar portions or panels  44 ,  46 ,  48  and  50 , each mounting an array  52  of UV-LED chips  54  and a center panel portion  56 . In it&#39;s simplest form, the structure  40  can include at least one elongated panel  44 ,  46 ,  48  or  50 . The UV LED chips  54  are preferably arranged in an offset staggered array on at least one panel  44 ,  46 ,  48  or  50 . Also, while the arrays  52  are shown in  FIG. 3  on the upper side of each panel portion  44 - 50 , it will be understood that this is only for the convenience of showing the arrays  52  and that actually, the arrays  52  are mounted on the underside of each panel portion  44 - 50 , as better shown in  FIG. 4 . 
         [0028]    In the apparatus  40  of  FIG. 3  or  4 , the center panel portion  56  is shown integral or connected to the panel portions  44 - 50  having the four arrays  52  of UV-LED chips, and is mounted to a shaft  58  at one end of a motor  60 , so that the panel portions  44 - 50  and the arrays  52  can be rotated relative to the disk  16 . It will be understood that a suitable support can be provided for the disk  16 , such as a pedestal (not shown). 
         [0029]    If desired at least one row of UV LED chips  54  can emit light in the visible light spectrum whereby a user can visually determine that power is being supplied to the array (s)  52  of UV LED chips  54 . 
         [0030]    Further, a heavier than air or lighter than air, non-oxygen, non-combustion supporting gas can be provided in the area between the panel portions  44 ,  46 ,  48  and  50  and the product to enhance curing. Also, the gas can be circulated by a fan to enhance cooling of the UV-LED chips  54  and heat dissipating fins can be mounted on the top side of the panels  44 - 50  to further enhance cooling of the UV-LED chips  54 . 
         [0031]    Advantageously, in the apparatus  40  of  FIG. 4 , a glass or plastic plate  62  is positioned between the UV-LED arrays  52  mounted on the undersides of the four panel portions  44 - 50  and the top of the disk  16 . The disk  16  can have one or more UV curable photo initiators in or on the upper surface of the disk  16 . 
         [0032]    In the apparatus  40  of  FIG. 4 , there is provided at least one, generally vertically arranged, auxiliary array  64  of UV-LED chips  66  that can be mounted on a generally upright vertical panel  68  positioned adjacent the periphery of the disk  16  to provide curing light at the side or periphery of the disk  16 . Also, a plastic or glass sheet or plate  70  can be positioned between the auxiliary array  64  and the disk  16  to shield the UV-LED chips  66  from splatter. 
         [0033]    If desired, the upright panel  68  ( FIG. 4 ) can be attached to and/or depend from one of the horizontal panel portions  44 - 50 . Alternatively, each of the horizontal panel portions  44 - 50  can have an upright panel  68  attached thereto and/or depending therefrom, with the shielding sheet or plate  70  attached to the upright panel(s)  68  in front of the array  64 . 
         [0034]    The glass or plastic sheets described above for the apparatus of  FIGS. 2 and 4  are preferably transparent or translucent, as well as rigid or semi-rigid, to provide impact-resistant light transmissive barriers to protect and shield the UV LED chips from splatter, dust, particularly, liquid containing UV photo initiators and other liquids. 
         [0035]    The disk-shaped product or the at least one elongate panel can be rotated a predetermined number of times between two and twenty (20) to enhance polymerization and curing of the UV curable photo-initiators. Insertion and ejection mechanisms can be provided for sequentially moving a disk-shaped product onto and off of the stationary or rotatable support pad or pedestal in a mass production operation of the apparatus of the present invention. 
         [0036]    Among the many advantages of the rotary UV curing method and apparatus of the invention are:
       1. The disk-shaped product or at least one panel having an array of offset staggered UV-LED chips thereon can be rotated.   2. A transparent or translucent glass or plastic shield can be provided for maintaining the UV-LED chips free from debris.   3. A non-oxygen gas can be provided for enhancing curing and can be circulated to enhance cooling of the UV-LED chips.   4. Outstanding curing.   5. Excellent results.   6. Greater product output.   7. Super quality.   8. Fewer defective products.   9. User friendly.   10. Economical.   11. Efficient.   12. Effective.       
 
         [0049]    From the foregoing description, it will be apparent that the method and apparatus of the present invention have a number of advantages, some of which have been described above and others of which are inherent in the invention and examples. 
         [0050]    Although embodiments of the invention have been shown and described, it will be understood that various modifications and substitutions, as well as rearrangements of components, parts, equipment, apparatus, process (method) steps, and uses thereof, can be made by those skilled in the art without departing from the teachings of the invention. Accordingly, the scope of the invention is only to be limited as necessitated by the accompanying claims.