Abstract:
A solar-powered lighting system includes a substrate, wherein at least one solar chip is disposed on one lateral side of the substrate, and at least one light source is disposed on one lateral side of the substrate. Solar light enters the substrate and propagates therein. Solar light energy is collected by the at least one solar chip which transforms the solar light energy into electrical power for the at least one light source to emit light to the substrate, before propagating therein and leaving the substrate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/176,040, filed on May 6, 2009. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The invention relates to a multifunction solar-powered lighting system, and in particular relates to a multifunction solar-powered lighting system, wherein solar light is guided to solar chips by a substrate to generate electrical power which is provided to a light source to emit light to the substrate. 
     2. Description of the Related Art 
     A conventional solar-powered signboard is shown in  FIG. 1 . A solar chip module  7  is disposed above the signboard  5 . During the day, solar light enters the solar board  7  to generate electrical power. The electrical power is provided to a light source  9  at night. In such a structure, however, the solar chip module  7  and the signboard  5  must be separated, which may hinder design and appearance of the signboard. 
     SUMMARY 
     An embodiment of a solar-powered lighting system of the invention comprises a substrate, wherein at least one solar chip disposed on one lateral side of the substrate, and at least one light source disposed on one lateral side of the substrate. Solar light enters the substrate, and is propagated therein, so that solar light energy may be collected by the at least one solar chip to transform the solar light energy into electrical power for the at least one light source to emit light to enter the substrate, propagate therein and leave the substrate. 
     Preferably, the at least one light source comprises at least one light emitting diode. 
     Preferably, the substrate comprises at least one light diffusion layer and a plurality of light guiding layers adjacent to the light diffusion layer. Solar light enters the substrate and is diffused by the light diffusion layer. The diffused solar light is reflected by an interface of the light diffusion layer and the light guiding layer to be collected by the at least one solar chip. A portion of the solar light enters the light guiding layers and is reflected by the interface of the light guiding layers, and the reflected light is collected by the at least one solar chip. The light emitted from the light source is emitted to the substrate and is guided by the light diffusion layer and the light guiding layers to leave the substrate. 
     Preferably, the light diffusion layer has a haze of 5˜99. 
     The light guiding layers are preferably made of acrylic material, polycarbonate, polyethylene terephthalate, polyurethane, polyimide, silicon resin or glass. 
     The light diffusion layer is preferably made of acrylic material, polycarbonate, polyethylene terephthalate, polyurethane, polyimide or silicon resin. 
     Preferably, the light diffusion layer comprises light scattering particles. 
     Preferably, the light diffusion layer comprises a mixed material of two materials with different index of refractions. 
     Preferably, the light diffusion layer is an optical composite structure. 
     The solar-powered lighting system of the invention further comprises a power accumulator connected to the at least one solar chip and the at least one light source. The electrical power generated by the at least one solar chip is saved in the power accumulator, and the saved electrical power is provided to the at least one light source. 
     The substrate has a first surface and a second surface opposite to the first surface, and solar light passes through the first surface to enter the substrate and the emitted light from the at least one light source passes through the first surface to leave the substrate. 
     The solar-powered lighting system of the invention further comprises a pattern layer disposed in the substrate, on the first surface of the substrate or on the second surface of the substrate, wherein the light from the at least one light source is emitted to the pattern layer, before leaving the substrate. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  is a schematic view of a conventional solar-powered signboard; 
         FIGS. 2   a  and  2   b  depict an embodiment of a solar-powered lighting system of the invention, wherein  FIG. 2   a  is an exploded view, and  FIG. 2   b  is a assembled view; 
         FIGS. 3   a  and  3   b  depict another embodiment of a solar-powered lighting system of the invention, wherein  FIG. 3   a  is an exploded view, and  FIG. 3   b  is a assembled view; 
         FIG. 4  is a cross section view along line A-A of  FIG. 2   b;    
         FIG. 5  depicts a light diffusion layer of the solar-powered lighting system of the invention; 
         FIG. 6  depicts solar light being guided by a light diffusion layer and a light guiding layer; 
         FIGS. 7   a  and  7   b  depict an application of the solar-powered lighting system; 
         FIGS. 8   a  and  8   b  depict another application of the solar-powered lighting system; and 
         FIGS. 9   a  and  9   b  depict another application of the solar-powered lighting system. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     Referring to  FIGS. 2   a ,  2   b ,  3   a  and  3   b , a solar-powered lighting system comprises a substrate  100  which has a multi-layer structure. The detailed structure of the substrate  100  is described in the following paragraphs. 
     In  FIGS. 2   a  and  2   b , three solar chips  70  are disposed on three adjacent lateral surface of the substrate  100 . The solar chips  70  are serially connected and connected to a power accumulator  90 . A light source  80  is disposed on the other lateral surface of the substrate  100 . The light source  80  is a light emitting diode in this embodiment. 
     When the substrate  100  is disposed outdoors as a signboard, during the day, solar light enters the substrate  100 , and propagates in the substrate  100  having the multi-layer structure, so that solar light energy may be collected by the solar chips  70 . Solar light energy is transformed into electrical power which is saved in a power accumulator  90  connected to the at least one light source  80 . At night, the power accumulator  90  provides electrical power for the at least one light source  80  to emit light. The light from the at least one light source  80  enters the substrate  100  and is emitted to a pattern or text (not shown) in or on the substrate  100 , and then is guided by the multi-layer structure of the substrate  100  to leave the substrate  100 , which makes the pattern or text visible at night. 
     Referring to  FIGS. 3   a  and  3   b , four solar chips  70  are disposed on four lateral surface of the substrate  100 . Light sources  80  (light emitting diodes) are joined to the at least one solar chips  70  which are serially connected to a power accumulator  90 . The at least one solar chips  70  can be arranged in one row or two rows. If the capacity of the accumulator  90  is small or the area of the substrate  100  is small, only one row of solar chips  70  is needed. Solar light enters the substrate  100 , and propagates in the substrate  100 , so that solar light energy may be collected by the solar chips  70 . Solar light energy is transformed into electrical power which is saved in a power accumulator  90  connected to the light source  80 . At night, the power accumulator  90  provides electrical power for the light source  80  to emit light. The light from the light source  80  enters the substrate  100  and is emitted to a pattern or text (not shown) in or on the substrate  100 , and then is guided by the multi-layer structure of the substrate  100  to leave the substrate  100 , which makes the pattern or text visible at night. 
     Referring to  FIG. 4 , the solar-powered lighting system comprises a substrate  100 , wherein solar chips  70  are disposed on one lateral surface of the substrate  100 , and light sources  80  are disposed on another lateral surface of the substrate  100 . The substrate  100  comprises a first surface  101  and a second surface  102  opposite to the first surface  101 . Solar light passes through the first surface  101  to enter the substrate  100 . Light from the at least one light source  80  also passes through the first surface  101  to leave the substrate  100 . The lateral surfaces, on which the solar chips  70  and light sources  80  are respectively disposed, are perpendicular to the first and second surfaces  101  and  102 . 
     In this embodiment, a pattern layer  50  is disposed on the second surface  102 . A desired pattern or text is formed on the pattern layer  50 . Light from the light source  80  is emitted to the pattern layer  50  and is reflected by the pattern layer  50  to make the pattern or text visible. Although the pattern layer  50  is disposed on the second surface  102  in this embodiment, the pattern layer  50  may also be disposed on the first surface  101  or in the substrate  100 . When the pattern layer  50  is disposed on the first surface  101  or in the substrate  100 , the pattern or text of the pattern layer  50  covers a portion of the first surface  101  to allow solar light to enter the substrate  100 . 
     A detailed structure of the substrate  100  will now be described. The substrate  100  comprises a light diffusion layer  10  and light guiding layers  20 ,  30  and  40 . Solar light L enters the light diffusion layer  10 .  FIG. 2  depicts a more detailed structure of the light diffusion layer  10 . Light scattering particles  12  are distributed in the light diffusion layer  10 . When solar light L enters the light diffusion layer  10 , solar light is scattered by the light scattering particles  12 . The scattered light is reflected by the interface of the light diffusion layer  10  so that solar light energy may be collected by the solar chips  70 . The particles  12  are preferably transparent but have different index of refractions from the material of the light diffusion layer  10 . 
     A portion of the solar light L penetrates the light diffusion layer  10  to enter the light guiding layer  20  as shown in  FIG. 3 . Since the index of refraction of the light diffusion layer  10  is different from the light guiding layers  20 ,  30  and  40 , the solar light is refracted when the solar light enters the light guiding layer  20 , and the refracted light is reflected by the interface of the light guiding layer  20  so that solar light energy may be collected by the solar chips  70 . 
     The light guiding layers  20 ,  30  and  40  are made of acrylic material, polycarbonate, polyethylene terephthalate, polyurethane, polyimide, silicon resin or glass. The light diffusion layer is made of acrylic material, polycarbonate, polyethylene terephthalate, polyurethane, polyimide or silicon resin. 
     The solar chips can be III-V column solar chips, single crystal silicon solar chips, poly crystal silicon solar chips or CIGS solar chips. 
     The solar-powered lighting system of the invention has many applications, some of which are illustrated in Table 1. 
     
       
         
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Effeteness 
                 Substrate Haze 
                 Application Category 
               
               
                   
                   
               
             
             
               
                   
                 Excellent 
                 80~99 
                 Windows, Skylights, 
               
               
                   
                   
                   
                 Warning Devices 
               
               
                   
                 High 
                 60~80 
                 Windows, French Windows, 
               
               
                   
                   
                   
                 Signboards, Warning 
               
               
                   
                   
                   
                 Devices, Art Glass 
               
               
                   
                 Medium 
                 40~60 
                 Skylights, French Windows, 
               
               
                   
                   
                   
                 Signboards, Route Marks, 
               
               
                   
                   
                   
                 Art Glass 
               
               
                   
                 Low 
                 20~40 
                 French Windows, 
               
               
                   
                   
                   
                 Signboards, Flat Display 
               
               
                   
                   
                   
                 Devices, Route Marks, 
               
               
                   
                   
                   
                 Art Glass 
               
               
                   
                 Very Low 
                  5~20 
                 French Windows, 
               
               
                   
                   
                   
                 Signboards, 
               
               
                   
                   
                   
                 Flat Display Devices, 
               
               
                   
                   
                   
                 Art Glass, 
               
               
                   
                   
                   
                 Planar Light Sources 
               
               
                   
                   
               
             
          
         
       
     
     A suitable application for high haze substrates may be warning devices, whereas a suitable application for low haze substrates may be planar light sources or flat display devices. 
       FIGS. 7   a  and  7   b  illustrate the solar-powered lighting system of the invention being applied to a signboard.  FIG. 7   a  illustrates the light source being turned off;  FIG. 7   b  illustrates the light source being turned on. The substrate comprises light diffusion plates having a haze of 31, a length of 445 mm, a width of 235 mm, a thickness of 3 mm and two glass plates with a thickness of 5 mm. Sixteen solar chips and eight LEDs with 0.1 W of power are disposed around the substrate. The electrical power generated by the solar-powered lighting system is 1.14 W. It is noticed, that the pattern layer (pattern and text) is formed in the first surface. 
       FIGS. 8   a  and  8   b  illustrate the solar-powered lighting system of the invention being applied to a traffic sign.  FIG. 8   a  illustrates the light source being turned off;  FIG. 8   b  illustrates the light source being turned on. The substrate comprises a PC light diffusion plate having a haze of 41, a length of 95 mm, a width of 95 mm, a thickness of 3 mm and two glass plates with a thickness of 5 mm. Eight solar chips and four LEDs with 0.05 W of power are disposed around the substrate. The electrical power generated by the solar-powered lighting system is 0.16 W. It is noted, that the pattern layer (pattern and text) is formed in the first surface. 
       FIGS. 9   a  and  9   b  illustrate the solar-powered lighting system of the invention being applied to an electronic book.  FIG. 9   a  illustrates the light source being turned off;  FIG. 9   b  illustrates the light source being turned on. The substrate comprises a PC light diffusion plate having a haze of 14, a length of 155 mm, a width of 85 mm, a thickness of 3 mm and two glass plates with a thickness of 5 mm. Eight solar chips and eight LEDs with 0.05 W of power are disposed around the substrate. The electrical power generated by the solar-powered lighting system is 0.04 W. It is noted that the pattern layer (pattern and text) is formed in the first surface. 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.