Patent Publication Number: US-2011073748-A1

Title: Light sensing device for solar tracking system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a light sensing device, more particularly to a light sensing device for solar tracking system. 
     2. Description of the Related Art 
     A stationary solar panel may only receive sunlight with a predetermined angle. The incident angle of sunlight with respect to the solar panel varies with latitude, season and time resulting from the revolution and rotation of the earth, so the stationary solar panel may be lack of efficiency in receiving sun&#39;s energy. A light tracking controller has been developed to resolve this issue. The light tracking controller utilizes light sensors located at different positions on a solar panel. The light sensors generate electric potential when the light sensors are illuminated. The solar panel may be controlled by a control chip to rotate automatically according to potential differences between the light sensors. 
     However, a conventional light tracking controller is insensitive to the variation of the position of the sun because the light sensors directly receive sunlight within a wide incident angle, so the tacking accuracy is affected. Besides, the cost of utilizing a CMOS as a light sensor is high, which is a disadvantage to commercial applications. Accordingly, developing a light sensor sensitive to light angle with low cost is a current goal to be achieved. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to provide a light sensing device for solar tracking system utilizing a light guiding element with an elongate light receiving face thereby being sensitive to the incident angle of sunlight to improve the accuracy of a solar tracking system. 
     One embodiment of light sensing device for solar tracking system according to the present invention comprises a light blocking plate, a light blocking cover, a light guiding element and a light sensor. The light blocking plate is disposed upright. The light blocking cover with a containing space is disposed at one side of the light blocking plate, wherein the light blocking cover includes an elongate opening facing upward. The light guiding element is disposed within the containing space of the light blocking cover, wherein the light guiding element comprises an elongate light receiving face and a light outputting face and the elongate light receiving face of the light guiding element is exposed to the elongate opening of the light blocking cover for receiving a light from outside to pass from the elongate light receiving face of the light guiding element through the light outputting face of the light guiding element. The light sensor is disposed beside the light guiding element for receiving the light emitted from the light outputting face of the light guiding element and generating an electric signal. 
     One embodiment of the light sensing device for solar tracking system comprises a light blocking plate, two light blocking covers, two light guiding elements and two light sensors. The light blocking plate is disposed upright. Each of two light blocking covers with a containing space, respectively, is disposed at one side of the light blocking plate, wherein each light blocking cover includes an elongate opening facing upward. Each light guiding element is disposed within each containing space of the light blocking cover, wherein each light guiding element comprises an elongate light receiving face and a light outputting face; each elongate light receiving face of the light guiding element is exposed to each elongate opening of the light blocking cover for receiving a light from outside to pass from the elongate light receiving faces of the light guiding elements through the light outputting faces of the light guiding elements. Each light sensor is disposed beside each light guiding element for receiving the light emitted from the light outputting faces of the light guiding elements and generating two electric signals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objectives, technical contents and characteristics of the present invention can be more fully understood by reading the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein: 
         FIG. 1  is an exploded view illustrating one embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 2  is a schematic diagram illustrating one embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 3  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 4  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 5  is a schematic diagram illustrating another embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 6  illustrates an example of sensing the position of the sun; 
         FIG. 7  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 8  is a schematic diagram illustrating another embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 9  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 10  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system according to the present invention; 
         FIG. 11  is a schematic diagram illustrating another embodiment of the light sensing device for solar tracking system according to the present invention 
         FIG. 12  illustrates another example of sensing the position of the sun. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 ,  FIG. 2 , which are respectively a exploded view and a schematic diagram illustrating one embodiment of the light sensing device for solar tracking system  1  according to the present invention. The light sensing device for solar tracking system  1  comprises a light blocking plate  11 , a light blocking cover  12 , a light guiding element  13  and a light sensor  14 . The light blocking plate  11  is disposed upright. The light blocking cover  12  with a containing space is disposed at one side of the light blocking plate  11 , wherein the light blocking cover  12  is made integrally or made by a plurality of elements and the light blocking cover  12  includes an elongate opening  121  facing upward. The position of the elongate opening  121  can be, but not limited to, within the range of the light blocking plate  11  so that light comes from the side opposite to where the light blocking cover  12  is located is blocked by the light blocking plate  11  to reach the elongate opening  121 . The elongate opening  121  can be, but not limited to, defined by the light blocking plate  11  and the light blocking cover  12  or configured on the light blocking cover  12 . 
     The light guiding element  13  is disposed within the containing space of the light blocking cover  12 , wherein the light guiding element  13  comprises an elongate light receiving face  131  and a light outputting face  132  and the elongate light receiving face  131  of the light guiding element  13  is exposed to the elongate opening  121  of the light blocking cover  12  (denoted in  FIG. 1 ), as shown in  FIG. 2 , for receiving a light from outside to pass from the elongate light receiving face  131  of the light guiding element  13  (denoted in  FIG. 1 ) through the light outputting face  132  (denoted in  FIG. 1 ) of the light guiding element  13  (denoted in  FIG. 1 ). Referring to  FIG. 1  again, for example, the light guiding element  13  comprises a light guiding plate. The elongate light receiving face  131  is a side wall of the light guiding element (the light guiding plate)  13 . A plurality of reflectors (not shown) are disposed at the face opposite to the light outputting face  132 . Reflectors may be ink dots formed by means of screen printing or convex dots formed by means of photolithography. When a light enters into the light guiding element (the light guiding plate)  13  from the elongate light receiving face  131 , reflectors reflect the light to the light outputting face  132 . 
     To be continued, the light sensor  14  is disposed beside the light guiding element (the light guiding plate)  13  for receiving the light emitted from the light outputting face  132  of the light guiding element (the light guiding plate)  13  and generating an electric signal, for example, the light sensor  14  may comprise a solar panel or a structure configured by at least one photoresistance or photodiode. 
       FIG. 3  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system  1 ′ according to the present invention. The light guiding element  13  of the light sensing device for solar tracking system  1 ′ may comprise a plurality of optic fibers and the elongate light receiving face  131  is defined by one terminal of each optic fiber while another terminal of each optic fiber facing the light sensor  14 . The light sensing device for solar tracking system  1 ′ further comprises a diffusion plate  15  disposed between the light guiding element  13  (the optic fibers) and the light sensor  14  for evenly diffusing the light emitted from the light guiding element (the optic fibers)  13  to the surface of the light sensor  14 . 
       FIG. 4  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system  2  according to the present invention comprising a light blocking plate  21 , a light blocking cover  22 , a light guiding element  23 , a light sensor  24 , a reflective plate  26  and a diffusion plate  25 . The light blocking plate  21  is disposed upright. Method for disposing the light blocking cover  12  with a containing space at one side of the light blocking plate  11  can be, but not limited to, embedding at least one insert  226  on the light blocking cover  22  into at least one slot  211  on the light blocking plate  21 . 
     To be continued, the light guiding element  23  is disposed within the containing space of the light blocking cover  22 , wherein the light guiding element  23  comprises an elongate light receiving face  231  and a light outputting face  232 , for example, the light guiding element  23  comprises a light guiding plate. The elongate light receiving face  231  is a side wall of the light guiding element (the light guiding plate)  23 . A plurality of reflectors (not shown) are disposed at the face opposite to the light outputting face  232 . Reflectors may be ink dots formed by means of screen printing or convex dots formed by means of photolithography. When a light enters into the light guiding element (the light guiding plate)  23  from the elongate light receiving face  231 , reflectors reflect the light to the light outputting face  232 . The elongate light receiving face  231  of the light guiding element (the light guiding plate)  23  (denoted in  FIG. 4 ) is exposed to the elongate opening  221  of the light blocking cover  22  (denoted in  FIG. 4 ), as shown in  FIG. 5 . 
     Referring to  FIG. 4  again, the reflective plate  26  is disposed between the light blocking plate  21  and the light guiding element (the light guiding plate)  23  for improving reflective efficiency. The light sensor  24  is disposed beside the light guiding element (the light guiding plate)  23  for receiving the light emitted from the light outputting face  232  of the light guiding element (the light guiding plate)  23  and generating an electric signal, for example, the light sensor  24  may comprise a solar panel or a structure configured by at least one photoresistance or photodiode. The diffusion plate  25  is disposed between the light guiding element (the light guiding plate)  23  and the light sensor  24  for evenly diffusing the light emitted from the light guiding element (the light guiding plate)  23  to the surface of the light sensor  24 . 
     It should be noted that the light blocking cover  22  is made integrally or made by a plurality of elements, for example, the light blocking cover  22  comprises a light blocking board  223 , a light blocking cage  224  and at least one pad  225 . Two pads  225 ,  225  of the light sensing device for solar tracking system  2  are disposed on the light blocking plate  21  and each pad  225  comprises a pad positioning aperture  225   a . Two ends of the light blocking board  223  comprise two positioning aperture  223   a ,  223   a , wherein each positioning aperture  223   a  corresponds to each pad positioning aperture  225   a . A locking element  27 , such as a screw or a bolt, is configured for penetrating through each positioning aperture  223   a  and each pad positioning aperture  225   a  to fix each pad  225  on the end of the light blocking board  223 , forming an elongate opening  221  facing upward, as shown in  FIG. 5 . Besides, two pads  225 ,  225  may block a lateral direction of light and the position of the elongate opening  221  can be, but not limited to, within the range of the light blocking plate  21 . 
     As shown in  FIG. 6 , two embodiments of the light sensing device for solar tracking system  2 ,  2  according to the present invention are arranged in symmetrical configuration with respect to a symmetry axis  60  to track the position of the sun. The actuating principle is described as follows: assuming that the sun is on the symmetry axis  60  in the beginning, then two electric signals, such as currents, generated by two light sensors (not shown in  FIG. 6 ) of the light sensing device for solar tracking system  2 ,  2 , respectively, are substantially identical. When the sun deviates from the symmetry axis  60 , the two electric signals become different because illuminated areas among two light sensing devices for solar tracking system  2 ,  2  are different. According to the difference of the two electric signals, a controlling circuit (not shown) electrically connected with two light sensors controls two light sensing device for solar tracking system  2 ,  2  to rotate with respect to the symmetry axis  60  until the two electric signals become identical. In other words, the sun is on the symmetry axis  60  again and the sun tracking is accomplished. Because the elongate opening  221  of each light blocking cover  22  only allows light within small incident angle range to enter each light guiding element (not shown in  FIG. 6 ) and generate a electric signal, sun tracking becomes sensitive to the variation of the position of the sun. Besides, the light sensing device for solar tracking system  2  according to the present invention may comprise a solar panel or a structure configured by at least one photoresistance or photodiode, so the manufacturing cost is lower than that of a solar tracking system utilizing a CMOS image sensor. The actuation mechanism and principle of the light sensing device for solar tracking system  1  and  1 ′ are the same as described above. The detail descriptions are skipped herein. 
       FIG. 7  and  FIG. 8  are respectively an exploded view and schematic diagram illustrating another embodiment of the light sensing device for solar tracking system  7  according to the present invention. As shown in  FIG. 7 , the light sensing device for solar tracking system  7  comprises a light blocking plate  71 , two light blocking covers  72 ,  72 , two light guiding elements  73 ,  73  and two light sensors  74 ,  74 . The light blocking plate  71  is disposed upright. Each of two light blocking covers  72 ,  72  with a containing space, respectively, is disposed on one side of the light blocking plate  71 , wherein each light blocking cover  72  includes an elongate opening  721  facing upward. The position of each elongate opening  721  can be, but not limited to, within the range of the light blocking plate  71  so that light comes from the side opposite to where each light blocking cover  72  is located is blocked by the light blocking plate  71  to reach each elongate opening  721 . Each elongate opening  721  can be, but not limited to, defined by the light blocking plate  71  and each light blocking cover  72  or configured on each light blocking cover  72 . 
     Each light guiding elements  73  is disposed within each containing space of the light blocking cover  72 , wherein each light guiding element  73  comprises an elongate light receiving face  731  and a light outputting face  732 ; each elongate light receiving face  731  of the light guiding element  73  is exposed to each elongate opening  721  of the light blocking cover  72  (denoted in  FIG. 7 ), as shown in  FIG. 8 , for receiving a light from outside to pass from each elongate light receiving faces  731  of the light guiding element  73  (denoted in  FIG. 7 ) through each light outputting face  732  of the light guiding element  73  (denoted in  FIG. 7 ). Referring to  FIG. 7  again, for example, each light guiding element  73  comprises a light guiding plate. Each elongate light receiving face  731  is a side wall of each light guiding element (the light guiding plate)  73 . A plurality of reflectors (not shown) are disposed at the face opposite to each light outputting face  732 . Reflectors may be ink dots formed by means of screen printing or convex dots formed by means of photolithography. When a light enters into each light guiding element (the light guiding plate)  73  from each elongate light receiving face  731 , reflectors reflect the light to each light outputting face  732 . 
     To be continued, each light sensor  74  is disposed beside each light guiding element (the light guiding plate)  73  for receiving the light emitted from each light outputting face  732  of each light guiding element (the light guiding plate)  73  and each light sensor  74  generates a electric signal, for example, each light sensor  74  may comprise a solar panel or a structure configured by at least one photoresistance or photodiode. 
       FIG. 9  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system  7 ′ according to the present invention. Each light guiding element  73  of the light sensing device for solar tracking system  7 ′ may comprise a plurality of optic fibers and each elongate light receiving face  731  is defined by one terminal of each optic fiber while another terminal of each optic fiber facing the light sensor  74 . The light sensing device for solar tracking system  7 ′ further comprises a diffusion plate  75  disposed between each light guiding element (the optic fibers)  73  and each light sensor  74  for evenly diffusing the light emitted from each light guiding element (the optic fibers)  73  to the surface of each light sensor  74 . 
       FIG. 10  is an exploded view illustrating another embodiment of the light sensing device for solar tracking system  10  according to the present invention comprising a light blocking plate  101 , two light blocking covers  102 ,  102 , two light guiding elements  103 ,  103 , two light sensors  104 ,  104 , two reflective plates  106 ,  106  and two diffusion plates  105 ,  105 . The light blocking plate  101  is disposed upright. Method for disposing each light blocking cover  102  with a containing space at one side of the light blocking plate  101  can be, but not limited to, embedding at least one insert  1026  on each light blocking cover  102  into at least one slot  1011  on the light blocking plate  101 . 
     To be continued, each light guiding element  103  is disposed within the containing space of each light blocking cover  102 , wherein each light guiding element  103  comprises an elongate light receiving face  1031  and a light outputting face  1032 , for example, the light guiding element  103  comprises a light guiding plate. The elongate light receiving face  1031  is a side wall of each light guiding element (the light guiding plate)  103 . A plurality of reflectors (not shown) are disposed at the face opposite to the light outputting face  1032 . Reflectors may be ink dots formed by means of screen printing or convex dots formed by means of photolithography. When a light enters into each light guiding element (the light guiding plate)  103  from the elongate light receiving face  1031 , reflectors reflect the light to the light outputting face  1032 . The elongate light receiving face  1031  of each light guiding element (the light guiding plate)  103  (denoted in  FIG. 10 ) is exposed to the elongate opening  1021  of each light blocking cover  102  (denoted in  FIG. 10 ), as shown in  FIG. 11 . 
     Referring to  FIG. 10  again, each reflective plate  106  is disposed between the light blocking plate  101  and each light guiding element (the light guiding plate)  103  for improving reflective efficiency. Each light sensor  104  is disposed beside each light guiding element (the light guiding plate)  103  for receiving the light emitted from the light outputting face  1032  of each light guiding element (the light guiding plate)  103  and generating an electric signal, for example, each light sensor  104  may comprise a solar panel or a structure configured by at least one photoresistance or photodiode. Each diffusion plate  105  is disposed between each light guiding element (the light guiding plate)  103  and each light sensor  104  for evenly diffusing the light emitted from each light guiding element (the light guiding plate)  103  to the surface of each light sensor  104 . 
     It should be noted that each light blocking cover  102  is made integrally or made by a plurality of elements, for example, each light blocking cover  102  comprises a light blocking board  1023 , a light blocking cage  1024  and at least one pad  1025 . Two pads  1025 ,  1025  of the light sensing device for solar tracking system  10  are disposed on the light blocking plate  101  and each pad  1025  comprises a pad positioning aperture  1025   a . Two ends of the light blocking board  1023  comprise two positioning aperture  1023   a ,  1023   a , wherein each positioning aperture  1023   a  corresponds to each pad positioning aperture  1025   a . A locking element  107 , such as a screw or a bolt, is configured for penetrating through each positioning aperture  1023   a  and each pad positioning aperture  1025   a  to fix each pad  1025  on the end of the light blocking board  1023 , forming an elongate opening  1021  facing upward, as shown in  FIG. 11 . Besides, two pads  1025 ,  1025  may block a lateral direction of light and the position of each elongate opening  1021  can be, but not limited to, within the range of the light blocking plate  101 . 
     As shown in  FIG. 12 , the actuating principle of the embodiment of the light sensing device for solar tracking system  10  according to the present invention is described as follows: assuming that the sun is on the extension line of the light blocking plate  101  in the beginning, and then two electric signals, such as currents, generated by two light sensors (not shown in  FIG. 12 ) of the light sensing device for solar tracking system  10  are substantially identical. When the sun deviates from the extension line of the light blocking plate  101 , the two electric signals become different because illuminated areas among two light guiding elements (not shown in  FIG. 12 ) of light sensing device for solar tracking system  10  are different. According to the difference of the two electric signals, a controlling circuit (not shown) electrically connected with two light sensors controls a motor (not shown) attached to the light sensing device for solar tracking system  10  to rotate until the two electric signals become identical. In other words, the sun is on the extension line of the light blocking plate  101  again and the sun tracking is accomplished. Because the elongate opening  1021  of each light blocking cover  102  only allows light within small incident angle range to enter each light guiding element (not shown in  FIG. 12 ) and generate a electric signal, sun tracking becomes sensitive to the variation of the position of the sun. Besides, the light sensing device for solar tracking system  10  according to the present invention may comprise a solar panel or a structure configured by at least one photoresistance or photodiode, so the manufacturing cost is lower than that of a solar tracking system utilizing a CMOS image sensor. The actuation mechanism and principle of the light sensing device for solar tracking system  7  and  7 ′ are the same as described above. The detail descriptions are skipped herein. 
     To sum up, the difference of electric signals between light sensors of the light sensing device for solar tracking system according to the present invention is utilized to track the sun, besides the elongate light receiving face of the light guiding element make the light sensing device sensitive to the variation of the position of the sun, so as to improve the accuracy of the sun tracking system. 
     The embodiments described above are to demonstrate the technical contents and characteristics of the preset invention to enable the persons skilled in the art to understand, make, and use the present invention. However, it is not intended to limit the scope of the present invention. Therefore, any equivalent modification or variation according to the spirit of the present invention is to be also included within the scope of the present invention.