Abstract:
A versatile system for producing channel letter coil of superior reflectivity and durability is described that includes providing a readily formable substrate. A first reflective material is disposed upon a first surface of the substrate. A second reflective material is disposed upon the first reflective material. An aesthetic material is disposed upon a second surface of the substrate. The entire substrate, with the reflective and aesthetic materials intact, is then rolled into a channel letter coil product, ready for immediate and efficient use in sign production.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority of U.S. Provisional Application No. 60/394,367, filed on Jul. 8, 2002. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The invention relates generally to the production of illuminated signs and, more specifically, to apparatus and methods for producing versatile channel letter coil. 
     BACKGROUND OF THE INVENTION 
     Channel letter coil is used in the production of illuminated signs that are most often associated with commercial enterprises such as restaurants, stores, and other businesses. Channel letter coil usually comprises a roll of readily formable metal (e.g., thin aluminum). A sign manufacturer takes the channel letter coil and, using a number of tools and methods, forms it into troughs (or channels) disposed upon or within the sign. These channels generally have the shape of particular individual characters (e.g., letters, numbers, symbols). A specialized light source (e.g., neon tubing or LEDs) of a desired shape or configuration is typically then disposed within the channel, and the channel and light may then optionally be covered over by some sort of protective or decorative lens, such as acrylic or film. 
     Conventionally, the coil material is supplied with a protective coating pre-applied to its surfaces for primarily aesthetic purposes but also, in part, to improve durability during handling, processing, and use. Typically, however, this pre-applied coating comprises a single layer of nominal thickness. Such conventional pre-applied coatings often do not, and are not intended to, enhance the performance or usability of the coil material as used in a finished channel coil sign product. 
     Manufacturers of finished channel coil sign products therefore often must, or choose to, apply additional coatings to enhance the durability and reflectivity of the channel coil. In some instances (e.g., outdoor signs) additional coatings may also be added to protect the interior of the sign from damaging outdoor conditions. Most often, however, additional coatings are applied to the backside (i.e., inner surface) of the channel coil to increase the effective intensity of the light emitted from the sign, without increasing its required power usage. Otherwise, the sign manufacturer may have to position additional light sources within the channel to achieve the desired illumination. 
     Exterior coatings may also be applied—as or to the topcoat—to provide various aesthetic effects (e.g., color). Although rolled coil material is typically supplied with some basic pre-painting, as previously noted, these special additional coatings are usually not applied to the coil material until after it has been unrolled and formed into its desired shape. This conventional type of application adds cost and inefficiency into the production process. 
     SUMMARY OF THE INVENTION 
     Thus, a versatile channel letter coil with enhanced reflectivity and aesthetic properties, without requiring a user of the coil to apply subsequent coatings, and a system for producing such versatile channel letter coil, is needed. Recognizing this, the present invention provides versatile channel letter coil of increased reflectivity that promotes desired illumination, and provides desired aesthetic effects, without requiring the application of additional coatings after channel formation. 
     Comprehending this, the present invention provides a system for producing channel letter coil of superior reflectivity and durability. A readily formable substrate is provided. A first layer of reflective material is then disposed upon a first surface of the substrate. A second layer of reflective material is disposed upon the first layer of reflective material. An optional outer aesthetic material is disposed upon a second surface of the substrate, typically opposite the reflective coatings. The substrate, having the reflective materials and any desired aesthetic materials disposed thereon, can then be easily formed into a finished channel letter coil product, ready for immediate and efficient use, without the necessity of applying additional coatings during the manufacturing and forming process 
     Other features and advantages of the present invention will be apparent to those of ordinary skill in the art upon reference to the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, including its features and advantages, reference is made to the following detailed description, taken in conjunction with the following drawing figures. Corresponding numerals and symbols in the different figures refer to corresponding parts unless otherwise indicated: 
         FIG. 1  illustrates an embodiment of channel letter coil material according to the present invention; and 
         FIG. 2  illustrates another embodiment of channel letter coil according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It should be apparent to those of skill in the art, upon reference to this disclosure, that the system and teachings of the present invention are applicable to a wide variety of channel letter coil configurations. For purposes of explanation and illustration, however, the present invention is hereafter described in reference to the production of a channel coil product using coil material of a particular size and composition. 
     The invention comprises various structures and methods for producing versatile channel letter coil product having superior production and performance characteristics. A channel letter coil of the invention comprises a coil substrate, upon which a series of coatings are disposed. The reflective and aesthetic properties of each coating, and the process of applying those coatings, are selected such that the cumulative effect of the coatings provides a channel letter coil of increased reflectivity. Whereas conventional channel letter coil may have a reflectivity of about 80%, as measured by ASTM International criteria, the present invention provides channel letter coil having reflectivity of above 90%. 
     Optionally, the selection of coating materials and their application may provide other desired effects, such as specific coloration or selective opacity. These benefits are delivered stock to the end user, without requiring additional treatment after the coil has been shaped and placed. A user can therefore cut production cycle times and costs. 
     A channel letter coil is now described in greater detail with reference to  FIG. 1 .  FIG. 1  provides a cross-sectional representation of segment  100  of channel letter coil stock according to the present invention. Segment  100  comprises substrate  102 , having a layer of material  104  disposed upon its inner surface. This surface is commonly referred to as the backside, being the surface that is formed into the inner portion of a finished channel product. A second layer of material  106  is disposed upon layer  104 . Segment  100  further comprises a topcoat layer of material  108  disposed upon the outer surface of substrate  102 . This outer surface forms the exterior portion of a finished channel product. 
     Substrate  102  comprises a readily formable metal of a desired size and durability. For example, a commercially available aluminum substrate (e.g., Alloy 3105/Temper H14) may be used. Other similar compositions may be used, in addition to other metals. 
     Substrate  102  may be provided in a flat sheet configuration, or may come already rolled. If substrate  102  is already rolled, then it should be unrolled. Once a flat substrate  102  is ready, material  104  is applied to the backside surface. Material  104  may comprise a number of coatings, depending upon the desired results. In segment  100 , material  104  comprises a reflective thermo-set polyester coating. Alternatively, fluoropolymer, acrylic, or other coatings of suitable durability and aesthetic value may be used. Material  104  may be provided in a variety of colors, of varying opacity. Preferably, material  104  is completely opaque and highly reflective, so as to cover the surface material of substrate  102  with a desired reflective color. Typically, material  104  is white. Material  104  may be applied in a number of ways. As depicted in segment  100 , material  104  is rolled on using a commercially available coating machine. Alternatively, material  104  may be painted on manually, be sprayed or sputtered on, or may be applied as an adhesive sheet. 
     After material  104  is applied, material  106  is then applied over material  104 . Material  106  may also comprise a number of coatings, depending upon the desired results. Typically, material  106  comprises the same material as material  104 . Alternatively, material  106  may comprise a different material, depending upon the desired characteristics of the coil being produced. As depicted in segment  100 , material  106  comprises a reflective thermo-set polyester coating. Alternatively, fluoropolymer, acrylic, or other coatings of suitable durability and aesthetic value may be used. Material  106  may be provided in a variety of colors, of varying opacity and reflectivity. Material  106  may be of similar color and/or opacity to material  104 , and is typically, although not necessarily, white. Material  106  may also be applied in a number of ways. As depicted in segment  100 , material  106  is rolled on using a commercially available coating machine. Alternatively, material  106  may be painted on manually, be sprayed or sputtered on, or may be applied as an adhesive sheet. 
     Material  108  is applied as a topcoat to the outer surface of substrate  102 . This may be done before, after, or concurrent with the application of materials  104  and  106 . Material  108  may comprise a number of cosmetic, aesthetic or functional coatings, depending upon the desired results. In segment  100 , material  108  comprises a polyester coating of a desired color and gloss. Alternatively, fluoropolymer, acrylic, or other industrial coatings of suitable durability and aesthetic value may be used, as well as conventional paints or glosses. Material  108  may be provided in a variety of colors, of varying opacity. Preferably, material  108  is completely opaque, so as to cover the surface material of substrate  102  with a desired color or appearance. Material  108  may be applied in a number of ways. As depicted in segment  100 , material  108  is rolled on using a commercially available coating machine. Alternatively, material  108  may be painted on manually, be sprayed or sputtered on, or may be applied as an adhesive sheet. 
     In segment  100 , materials  104  and  106  are applied in separate steps. In alternative embodiments, however, materials  104  and  106  may be applied together in a single step, especially where they comprise the same material having the same characteristics. The combined layers of materials  104  and  106  provide a significant advantage in improving the overall reflectivity of the product. Although the combined thickness of layers  104  and  106  can vary over a wide range, their combined thickness is typically within the range of 1.2 to 1.4 mils. This provides a significant improvement in the reflectivity over conventional methods, where the overall thickness of the reflective material is usually within the range of about 0.8 mils. In alternative embodiments of the present invention, where only material  104  or  106  is applied in a single layer, that layer is applied to a thickness within the range of 1.2 to 1.4 mils. 
     Again, the film coating comprising materials  104  and  106  is disposed on the backside surface of substrate  102  (i.e., the surface that is formed into the inner surface of a finished channel letter coil product). The coating comprising material  108  is disposed as a topcoat on the outer surface of substrate  102 . 
     After material  104  is applied, segment  100  may be heated, if necessary, to form and set it in place. In one embodiment of the invention, heating of about 420° F.-500° F., for about 25 seconds, is sufficient. Persons skilled in the art will understand that heating temperatures and times will vary depending upon factors such as the specific type of thermo-set material used. This process is repeated after material  106  is applied. Alternatively, heating may be done only after both materials  104  and  106  are applied, depending upon their composition and the desired characteristics of segment  100 . Persons skilled in the art will also recognize that, due to the heating of segment  100 , the composition and characteristics of material  108  may dictate whether it is applied before, after, or concurrent with materials  104  and  106 . 
     After materials  104 ,  106 , and  108  are securely disposed upon substrate  102 , segment  100  is then rolled to form coil  200 , as depicted in  FIG. 2 . Coil  200  now comprises finished channel letter coil material, ready for forming into finished channel letter coil products without requiring further application of reflective coatings or paints. The user may thereby produce signs of standard luminosity that require lower power, or may produce signs of standard power that provide increased luminosity. Depending upon the specific application, however, a user may optionally apply further coatings or paints to effect a desired cosmetic effect (e.g., unusual color, etc.). 
     While the invention has been described in reference to illustrative embodiments, the description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.