Patent Publication Number: US-2009231834-A1

Title: Backlight panel and manufacturing method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation Application of U.S. patent application Ser. No. 11/504,515, filed Aug. 14, 2006, which further claims the benefit of U.S. Provisional Application No. 60/708,572 filed Aug. 16, 2005. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a fluorescent (or LED) illuminated backlight panel and more particularly, to an improved backlight panel including a twinwall plastic lampholder sheet, comprised of a multiplicity of longitudinal tubes for properly spacing, housing and protecting the inserted fragile fluorescent lamps or LED strips. 
     In recent years there has been an industry-wide, customer-driven desire for display lightboxes which are very thin; changes in the Americans With Disabilities Act (ADA) mandated lightboxes that could protrude no more than three inches from the wall. Previously, normal interior-use lightboxes were, on the average, five-to-six inches thick. Through creativity and better engineering, top-quality fluorescent lightboxes were able to be manufactured to about three inches in depth; two-sided lightboxes are typically five to six inches deep. 
     With the advent of acrylic, edge-lit lightpanels, lightboxes were able to be manufactured to a depth of between one and two inches but at great expense. 
     However, the standard backlit fluorescent lightboxes are very heavy, relatively deep, use a lot of power and have limited lamp life. Edgelit lightboxes are thin, but they are very heavy, very expensive, very difficult to service and are not very bright. The lamps used in edge-lightpanels, normally CCFL&#39;s (cold-cathode fluorescent lamps) or EEFL&#39;s (external electrode fluorescent lamps) are extremely fragile. It is also very difficult, in all forms, to make a thin, bright, curved lightbox or lightpanel. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is comprised of a thin, tough, hollow, twinwall plastic sheet; into this sheet is inserted one or a series of (parallel) thin fluorescent lamps or LEDs; the tough, rigid, twinwall sheet provides protection for the lamps or LEDs, along with a method for mounting the lights and providing the proper spacing between the lights. 
     The lamps, either CCFLs, EEFLs, thin fluorescent lamps, or LEDs are protected from shock and breakage by being contained within the tough, rigid, plastic lampholder sheet. By varying the placement of the lamps or LEDs in alternate hollow tubes, the spacing of the lamps or LEDs (the distance between lamps or LEDs) is easily changed, thus altering the numbers of lights and the brightness of the sheet. Double-sided lightboxes can be easily and inexpensively manufactured to under three inches in depth. The rigidity and protection afforded by the plastic lampholder sheet allows for the ease of manufacture of lightpanels for use without the necessity of additional protection by metal or plastic cover-bodies, since the plastic lampholder sheet serves as both protection for the lamps and LEDs and as method of lamp and LED mounting. The present invention may be curved by longitudinally slitting-through a series of the hollow, square tubes on one-or-two sides of the sheet (kerfing), allowing the sheet to bend, yielding a flexible backlight panel. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  Is an end-view of a plastic lampholder sheet, comprised of: 
       A. Broad parallel wall (# 1 ) 
       B. Broad parallel wall (# 2 ) 
       C. Longitudinal rib (# 3 ) 
       D. Hollow square tube (# 4 ) 
         FIG. 2  Is a perspective view of a plastic lampholder sheet. 
         FIG. 3  Is a perspective view showing lamps inserted into a plastic lampholder sheet. 
         FIG. 4  Is a perspective view of a plastic lampholder sheet in which the hollow square tubes that contain the fluorescent lamps are shorter than the adjacent hollow square tubes, providing for extra protection for the ends of the fluorescent lamps. 
         FIG. 5  Is a perspective view of a plastic lampholder sheet with fluorescent lamps inserted and wiring harness attached. 
         FIG. 6  Is a perspective view showing an LED strip inserted into a plastic lampholder sheet 
         FIG. 7  Is a perspective view of a plastic lampholder sheet which has been slit, cut or otherwise kerfed in order to provide flexibility to the backlight panel. 
         FIG. 8  Is a close-up of the perspective view of a plastic lampholder sheet which has been slit, cut or otherwise kerfed in order to provide flexibility to the backlight panel. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention discloses a backlight including fluorescent lamps or LEDs and a method for driving the same. The backlight is constructed in a manner that a multiplicity of fluorescent lamps or LEDs are inserted into a series of hollow, square, parallel plastic tubes supported between two parallel plastic walls ( FIG. 3 ). The plastic tubes and walls are preferably extruded from polycarbonate, although other plastic types and manufacturing methods may be utilized. Round plastic tubes may also be used. 
     The backlight of the present invention is illuminated via fluorescent lamps or LEDs, employing, but not limited to, cold-cathode fluorescent lamps, external electrode fluorescent lamps or LEDs ( FIGS. 3 ,  5  and  6 ). These lamps are typically driven by, but are not limited to, commercially available inverters utilizing a square wave, sine wave, fluorescent ballasts or switching power supplies. A wiring harness is utilized to carry the proper voltage, current and frequency to the ends of each lamp or LED ( FIGS. 5 and 6 ). 
     The present invention is an improvement on the prior art because: 
     1. The lamps, either CCFLs, EEFLs, thin fluorescent lamps, or LEDs are protected from shock and breakage by being contained within the plastic lampholder sheet, either with or without plastic, rubber or synthetic, square, circular, or shaped “O”-ring types of spacers encircling the lamps. 
     2. By varying the placement of the lamps or LEDs in alternate hollow square tubes, the spacing of the lamps or LEDs (the distance between lamps) is easily changed. This change in lamp or LED spacing alters the number of lamps or LEDs used in the lightpanel, thus changing the brightness of the lightpanel and altering the distance needed between the plane of the lamps and an illuminated substrate in order to achieve even illumination across the face of the illuminated substrate. 
     3. The mounting (insertion) of the lamps within the hollow tubes of the transparent or translucent plastic lampholder sheet allows for the very easy manufacture of double-sided lightpanels and lightboxes, since the illumination from the lamps shines out of both sides of the lampholder sheet, if it is transparent or translucent. Double-sided lightboxes can be easily and inexpensively manufactured to under three inches in depth. 
     4. The imprinting of translucent material, dots, lines or other light-reducing methods onto the face of the square, hollow tubes, directly in front of the lamps, easily allows for increased control of the intensity and evenness of illumination of the light panel. 
     5. The rigidity and protection afforded by the plastic lampholder sheet allows for the ease of manufacture of lightpanels for use without the necessity of additional protection by metal or plastic cover-bodies, since the plastic lampholder sheet serves as both protection for the lamps and LEDs and as method of lamp and LED mounting. 
     6. The slitting of one side of the hollow, square tubes(s), parallel to the longitudinal ribs, on one or both sides of the broad, parallel walls, allows the lampholder sheet to bend. This yields a flexible lightpanel. 
     7. The use of CCFLs, EEFLs or LEDs in the present backlight panel improves the prior backlight panel art due to the long life of the lamps used, requiring less service and maintenance. 
     8. Because of all of the above, and more, lightpanels, lightboxes and other products manufactured utilizing the present invention are lighter, less expensive, brighter, illuminated more evenly, require less service and are generally thinner than when using other comparable methods of illumination