Abstract:
A simulated sunlight generating device for generating a simulated sunlight required for evaluating performance of solar cells includes a plurality of driving units, a plurality of light-emitting units, and a plurality of adjusting units. The driving units drive the light-emitting units to emit light. The adjusting units enable the light of the light-emitting units to not only propagate along the same light route but also be added up and combined to form the simulated sunlight of an intended wavelength with ease of installation, ease of maintenance, low costs, high flexibility, and high efficiency.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 100116316 filed in Taiwan, R.O.C. on May 10, 2011, the entire contents of which are hereby incorporated by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to simulated sunlight generating devices, and more particularly, to a simulated sunlight generating device for generating a simulated sunlight by adding up and combining light rays emitted from a plurality of light-emitting units. 
       BACKGROUND OF THE INVENTION 
       [0003]    To conduct indoors a test on a solar cell composed of a plurality of cells according to the prior art, it is necessary to simulate sunlight required for the evaluation of the performance of the solar cell in utilizing sunlight. 
         [0004]    Referring to  FIG. 1 , there is shown a schematic view of a conventional simulated sunlight generating device. The simulated sunlight-based test involves driving a light-emitting diode array  2  to emit a high-brightness light L for functioning as the simulated sunlight. The light-emitting diode array  2  comprises a plurality of light-emitting diodes  22 . The light-emitting diodes  22  each emit the light L. The light L emitted from each of the light-emitting diodes  22  travels a distance d before reaching cells  42  of a solar cell  4  to undergo a test. The distance d, however, opens up a possibility that the light L from any one of the light-emitting diodes  22  misses one of the cells  42 , or, in other words, the possibility that one of cells  42  does not necessary receive the full illumination intensity of the light L from the light-emitting diodes  22 , for reasons below. The light-emitting diodes  22  each emit the light L by a scattering angle θ. If each of the cells  42  is to receive the light L from all the light-emitting diodes  22 , each of the cells  42  will have to be present within the range of angle covering all the scattering anglesθ 0 . In practice, it is impossible for any one of the cells  42  to fall within the range of angle covering all the scattering angles θ of the light-emitting diodes  22 . The above drawbacks of the prior art cannot be overcome by reducing the distance d between the light-emitting diodes  22  and the solar cell  4  or positioning the light-emitting diodes  22  immediately above the cells  42 , respectively. 
         [0005]    Accordingly, it is imperative to provide a simulated sunlight specific to one and only one cell or even specific to a solar cell in its entirety. To this end, the present invention provides a simulated sunlight generating device that is easy to install and maintain, incurs low costs, and is highly flexible and efficient. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an objective of the present invention to provide a simulated sunlight generating device for generating a simulated sunlight by adding up and combining light rays emitted from a plurality of light-emitting units. 
         [0007]    Another objective of the present invention is to provide a simulated sunlight generating device for generating a simulated sunlight required for the evaluation of the performance of a solar cell in utilizing sunlight. 
         [0008]    In order to achieve the above and other objectives, the present invention provides a simulated sunlight generating device for generating a simulated sunlight, comprising: a plurality of driving units for generating a plurality of driving currents; a plurality of light-emitting units connected to the driving units for emitting light of corresponding wavelength and illumination intensity based on the driving currents, respectively; and a plurality of adjusting units disposed at a light-emitting route of the light-emitting units for changing light-emitting directions of the light-emitting units, respectively, and enabling the light of the light-emitting units to not only propagate along a same light route but also be added up and combined to form the simulated sunlight. 
         [0009]    Unlike the prior art, the present invention provides a simulated sunlight generating device for generating simulated sunlight of the same wavelength and illumination intensity per unit area to optimize simulation of sunlight. In addition to optimization, the simulation of sunlight, as effected by the simulated sunlight generating device of the present invention, features variability and flexibility, because the light-emitting units are separately driven and thereby can be different from each other in terms of the wavelength of the light rays emitted, such that the emitted light rays of different wavelengths can be added up or combined to generate the simulated sunlight of one, some, or all of the wavelengths. Furthermore, the simulated sunlight is generated in a light-emitting direction after light rays emitted from the light-emitting units have been added up or combined by the adjusting units; hence, the simulation of sunlight demonstrates high efficiency and high directivity. By contrast, as disclosed in the prior art, conventional light-emitting units generate the simulated sunlight in a light-emitting direction directly, and thus the simulation of sunlight is inefficient due to variation in the characteristics of the light-emitting units. Accordingly, the present invention provides a simulated sunlight generating device that is easy to install and maintain, incurs low costs, and is highly flexible and efficient. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Objectives, features, and advantages of the present invention are hereunder illustrated with specific embodiments in conjunction with the accompanying drawings, in which: 
           [0011]      FIG. 1  (PRIOR ART) is a schematic view of a conventional simulated sunlight generating device; 
           [0012]      FIG. 2  contains a schematic view of the architecture of a simulated sunlight generating device and a graph of light intensity versus wavelength according to an embodiment of the present invention; and 
           [0013]      FIG. 3  contains a schematic view of the architecture of another simulated sunlight generating device and a graph of light intensity versus wavelength according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    Referring to  FIG. 2 , there are shown a schematic view of the architecture of a simulated sunlight generating device and a graph of light intensity versus wavelength according to an embodiment of the present invention. As shown in  FIG. 2 , designed to generate a simulated sunlight SSL, a simulated sunlight generating device  10  comprises a plurality of driving units  122 - 128 , a plurality of light-emitting units  142 - 148 , and a plurality of adjusting units  162 - 168 . This embodiment is exemplified by four said driving units, four said light-emitting units, and four said adjusting units. 
         [0015]    The driving units  122 - 128  generate a plurality of driving currents I 1 -I 4 . The illumination intensity and wavelength of light emitted from the light-emitting units  142 - 148  being driven depend on the strength of the driving currents I 1 -I 4 . With the light-emitting units  142 - 148  being driven by the driving units  122 - 128  separately, the strength of the driving currents I 1 -I 4  is adjusted to equalize the illumination intensity of the light emitted. It is because the service life or modulation of the light-emitting units  142 - 148  depends on their driving characteristics and constituent materials. 
         [0016]    The light-emitting units  142 - 148  are connected to the driving units  122 - 128 , respectively. The light-emitting units  142 - 148  emit light L 1 -L 4  of wavelength λ 1 -λ 4  according to the driving currents I 1 -I 4 . For example, the light-emitting units  142 - 148  are light-emitting diodes, organic light-emitting diodes, or a combination thereof. In an embodiment, the light-emitting units emit light of wavelengths corresponding to that of the three primary colors (RGB). For example, in an embodiment, the simulated sunlight generating device  10  comprises driving units, light-emitting units, and adjusting units, wherein the RGB wavelengths of the simulated sunlight generated by the simulated sunlight generating device  10  are namely the red light wavelength 600nm˜700 nm, the green light wavelength 500˜600 nm, and the blue light wavelength 400nm˜500 nm. Hence, given the RGB wavelengths of the simulated sunlight thus generated, the simulated sunlight SSL thus generated is white visible light. After the light L 1 -L 4  generated by the light-emitting units  142 - 148  have been added up, the wavelength of the simulated sunlight SSL includes the wavelength of visible light and the wavelength of invisible light, wherein the wavelength of the simulated sunlight SSL ranges between 240 nm and 2400 nm. 
         [0017]    The adjusting units  162 - 168  are disposed at a light-emitting route of the light-emitting units  142 - 148 . The adjusting units  162 - 168  change the light-emitting directions of the light-emitting units  142 - 148 , respectively. The adjusting units  162 - 168  enable the light L 1 -L 4  of the light-emitting units  142 - 148  to not only propagate along the same light route but also be added up and combined to form the simulated sunlight SSL. For example, the adjusting units  162 - 168  veer the light L 1 -L 4  to a vertical direction simultaneously and confine the light L 1 -L 4  to the light route. Furthermore, the adjusting units  162 - 168  are beam splitters and/or reflectors. For example, in this embodiment, the reflectors change the light-emitting directions of the light L 1 -L 4  from the light-emitting units  142 - 148 , such that the light-emitting directions end up in the light route due to reflection. 
         [0018]    Referring to  FIG. 3 , there are shown a schematic view of the architecture of another simulated sunlight generating device and a graph of light intensity versus wavelength according to another embodiment of the present invention. As shown in  FIG. 3 , a simulated sunlight generating device  10 ′ generates the simulated sunlight SSL. In addition to the plurality of driving units  122 - 128 , the plurality of light-emitting units  142 - 148 , and the plurality of adjusting units  162 - 168  mentioned in the previous embodiment, the simulated sunlight generating device  10 ′ further comprises a plurality of condensation units  182 - 188  and/or a detection unit  20 . The condensation units  182 - 188  are disposed between the light-emitting units  142 - 148  and the adjusting units  162 - 168  for condensing the light L 1 -L 4  such that the light L 1 -L 4  thus condensed are focused on one of the adjusting units  162 - 168 . For example, the condensation units  182 - 188  are implemented in the form of a single lens or a lens assembly. A point to note is that, for a manufacturing-related reason, the light L 1 -L 4  may manifest directivity badly or have a large scattering angle, thereby compromising the condensation of the light L 1 -L 4 . Hence, the efficiency of the generation of the simulated sunlight SSL is enhanced, when the condensation units  182 - 188  condense and focus the light L 1 -L 4  on the adjusting units  162 - 168 . In another embodiment, the condensation units  182 - 188  are directly disposed on the light-emitting units  142 - 148  to achieve the aforesaid function and effect. 
         [0019]    The adjusting units  162 - 168  are beam splitters and/or reflectors. The beam splitters facilitate the detection of at least one of the light L 1 -L 4  or illumination intensity of the simulated sunlight SSL by the detection unit  20 , such that the status of the light L 1 -L 4  can be dynamically analyzed. This embodiment is exemplified by the detection of the illumination intensity of the simulated sunlight SSL. 
         [0020]    Unlike the prior art, the present invention provides a simulated sunlight generating device for generating simulated sunlight of the same wavelength and illumination intensity per unit area to optimize simulation of sunlight. In addition to optimization, the simulation of sunlight, as effected by the simulated sunlight generating device of the present invention, features variability and flexibility, because the light-emitting units are separately driven and thereby can be different from each other in terms of the wavelength of the light rays emitted, such that the emitted light rays of different wavelengths can be added up or combined to generate the simulated sunlight of one, some, or all of the wavelengths. Furthermore, the simulated sunlight is generated in a light-emitting direction after light rays emitted from the light-emitting units have been added up or combined by the adjusting units; hence, the simulation of sunlight demonstrates high efficiency and high directivity. By contrast, as disclosed in the prior art, conventional light-emitting units generate the simulated sunlight in a light-emitting direction directly, and thus the simulation of sunlight is inefficient due to variation in the characteristics of the light-emitting units. Accordingly, the present invention provides a simulated sunlight generating device that is easy to install and maintain, incurs low costs, and is highly flexible and efficient. 
         [0021]    The present invention is disclosed above by preferred embodiments. However, persons skilled in the art should understand that the preferred embodiments are illustrative of the present invention only, but should not be interpreted as restrictive of the scope of the present invention. Hence, all equivalent modifications and replacements made to the aforesaid embodiments should fall within the scope of the present invention. Accordingly, the legal protection for the present invention should be defined by the appended claims.