Patent Publication Number: US-6663255-B1

Title: Re-usable self-illuminating sign

Description:
BACKGROUND OF INVENTION 
     The phenomenon of chemiluminescence has been known for some time. This phenomenon is the basis of a number of inventions, including novelty items such as light sticks, glow bracelets and necklaces, and light wands, which may be seen at concerts, theme parks, etc. during the early evening and nighttime hours. The usual method of operation of these items is to bend, shake, or otherwise cause an internal, frangible container to break, resulting in the mixing of chemicals which exhibits a chemiluminescence reaction. These items are very inexpensive, and are essentially “throw away” items, as they cannot be reused. The basis for such items is described in U.S. Pat. No. 3,584,211, which discloses the “light stick”, in which a cylindrical container holds one chemical, and an internal, frangible, smaller cylindrical container contains a second chemical. When the cylinder is bent sufficiently, the internal container breaks, allowing the two chemicals to mix, causing the desired reaction. These novelty glow products typically continue to produce light for between 6 and 10 hours after being activated. 
     Chemiluminescence is used for more serious applications as well. These include safety applications under conditions where power sources, such as batteries, are not appropriate. For instance, divers use items similar to glow sticks to make them visible during night dives. 
     The present invention combines the light-producing qualities of chemiluminescent devices with the light-retaining qualities of photoluminescent materials. U.S. Pat. Nos. 4,992,302, and 6,008,012 describe methods for making photoluminescent powders, which can be incorporated in other materials, such as plastics, making the plastics themselves photoluminescent. Such materials may continue to glow for up to 10 hours after being exposed to light. 
     In the present invention chemiluminescent light sticks are combined with photoluminescent plastic to produce illuminated signs which are inexpensive, reusable, and do not require external power sources. As such, they are useful as toys, novelties, and safety devices. 
     SUMMARY OF INVENTION 
     It is an object of the present invention to provide a which contains its own source of illumination, and which is simple and inexpensive to build. 
     It is a further object of this invention that such a sign be re-usable. 
     In accordance with one aspect of the present invention, the source of the light is a chemiluminescent light stick. 
     In accordance with a second aspect of the invention, the light contains a display panel which is impregnated with photoluminescent powder. 
     In accordance with a third aspect of the invention the display panel has a mask on its face with cutouts through which the light created by the photoluminescent powder may be seen. 
     In accordance with a fourth aspect of the invention the display panel is part of a cylindrical body with triangular cross section. 
     In accordance with a fifth aspect of the invention the light stick fits snugly within the body, and is retained therein by friction. 
     In accordance with a sixth aspect of the invention the mask is formed on the display panel by stamping. 
     In accordance with an eighth aspect of the invention the mask is formed on the display panel by screening. 
     In accordance with a final aspect of the invention the body is formed from a single sheet of material impregnated with the photoluminescent powder, which contains tabs and slots to hold the body together when assembled. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     These, and further features of the invention, may be better understood with reference to the accompanying specification and drawings depicting the preferred embodiment, in which: FIG. 1 depicts a perspective view of the sign. 
     FIG. 2 depicts a perspective view of a light stick used as the source of illumination in the sign. 
     FIG. 3 depicts a sheet of material cut to shape, and with bend lines, tabs and slots which can be folded into the shape of the sign. 
    
    
     DETAILED DESCRIPTION 
     The present invention, in its preferred embodiment utilizes a light stick as a source of light, together with a plastic sheet impregnated with a photoluminescent powder, which stores and retransmits the light of the glow stick distributed over the surface of the sheet. The sheet thus becomes a photoluminescent surface. A mask covering the photoluminescent surface has cut-out portions so that the effect produced is that of an illuminated sign. 
     The light stick is of the type described in U.S. Pat. No. 3,584,211, wherein two chemicals are combined when the light stick is bent sufficiently to fracture a frangible container holding one of the chemicals, the resulting chemical reaction producing light by the well-known chemiluminescence. 
     The typical light stick is between 4 and 6 inches in length. There is no inherent limit to the length of the glow stick, and extended forms, including wands and necklaces are commonly available. However, the increase in diameter beyond about ½ inch becomes impractical because the amount of chemical involved becomes economically unfeasible. The inclusion of the photoluminescent surface in the present invention allows the illuminating effect of the light stick to be spread substantially uniformly over a surface are much larger than that of the light stick, producing a glowing sign several inches in width. 
     A sign in accordance with the preferred embodiment of the invention is shown in FIG.  1 . The body  2  of the sign has a triangular cross section, and is formed of a soft, translucent plastic material. The glow stick  6  has a diameter of ½ inch, and is 4 inches in length. The glow stick is shown in FIG. 2, and has a body  12  which is ½ inch in diameter, and a cap  10  about {fraction (3/16)} inch larger in diameter than the body. A suspension tab  14  is commonly found in such light sticks, but serves no purpose in the present invention. 
     The dimensions of the triangular sign body are such that the glow stick is snugly retained by friction. Thus the glow stick (also called a light stick), which is not reusable, may be replaced when the life of the chemiluminescent reaction expires. 
     The sign display surface  4  has a mask with the words “GLOWING RESULTS” cut out, so that the light of the photoluminescent surface shows through. 
     The sign body is formed from a single sheet of material in the preferred embodiment, as shown in FIG.  3 . The body is separated into thirds by the upper fold line  20  and the lower fold line  22 . The  2  display panel  4  is adjacent to the upper body  2  and the lower body  26 . Two tabs  18  in the lower body mate with slots  16  in the upper body, so that the body, when folded along the fold lines, retains the body in the form of a cylinder with triangular cross section. Friction may be used to keep the tabs within the slots, or adhesive, or heat bonding may be used as alternatives. 
     In an alternative embodiment the sign body and display are extruded or molded in a single piece. In a still further embodiment, the display panel is formed separately from the body, which need not be impregnated with the photoluminescent powder, although the display panel is so impregnated. 
     Although only the surface  2  need be photoluminescent, it has been found that making the entire sheet of FIG. 3 photoluminescent simplifies the manufacturing process. 
     The mask may be applied by a number of different methods, including screening, stamping, etc. 
     A typical sign made in accordance with this invention is about four to six inches in length, and two inches in width. There is no inherent limit to the length of the sign, however, and light wands are available in lengths up to several feet. 
     While the invention has been described with reference to specific embodiments, it will be apparent that improvements and modifications may be made within the purview of the invention without departing from the scope of the invention defined in the appended claims.