Patent Publication Number: US-2011048656-A1

Title: Blind device using solar cells

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. non-provisional patent application claims priority under  35  U.S.C. §119 of Korean Patent Application No. 10-2009-0080496, filed on Aug. 28, 2009, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention disclosed herein relates to a blind device using solar cells, and more particularly, to a blind device using solar cells, which improves the generating efficiency of the solar cells. 
     Recently, the importance of development of next generation clean energy resources is being emphasized because of issues such as the global warming due to carbon dioxide emission form fossil fuels, accidents of nuclear power plants, and radioactive contamination due to radioactive waste. Specifically, photovoltaic power generating systems (solar cells) using unlimited and semi-permanent sunlight are being regarded with much interest as next generation energy generating systems. 
     Such a solar cell is a semiconductor device that directly converts sunlight into electricity by using the photovoltaic effect in which light is irradiated on a semiconductor diode with p-n junction to generate electrons. The amount of voltage obtained from a unit solar cell is about 1 V or less, which is insufficient for any practical use. Thus, a solar cell module for generating power is manufactured by connecting a plurality of solar cells to each other in series and in parallel to generate predetermined voltage and current. 
     Such solar cell modules are extensively developed for various fields including plate type fixed generating facilities. For example, collapsible portable solar cell modules, curtains for adjusting light intensity, and blind devices including solar cells on blind slats to generate electricity have been developed. In this case, when solar cells are fully opened, a generating operation is effectively performed. However, when a portion of solar cells is collapsed or overlapped because of an insufficient space or the adjustment of light intensity, the portion shaded from light cannot generate electricity. When solar cells are connected to each other in series, a non-generating solar cell functioning as a resistor degrades the generating efficiency of a whole system, and heat generated from the non-generating solar cell may reduce the service life of the system and damage the system. 
     A bypass diode may be used in a typical plate type fixed solar cell module to form a circuit configured to bypass a solar cell having low generating capacity due to performance degradation or shadow. Typically, a unit solar cell has an electromotive force ranging from about 0.5 V to about 1 V, which is similar to a voltage drop value of a diode, so that it is inefficient to dispose a bypass diode on each cell. Thus, a bypass diode may correspond to a plurality of cells connected in series. In this case, voltage drop, which inevitably occurs in a diode, causes power loss through a bypass. 
     Specifically, in the case of a module including many slat type panels, such as a blind, when the panels respectively provided with bypass diodes overlap each other according to use condition, voltage drop occurs through the bypass diodes. When a bypass diode is attached to two or more slat type panels, some of the panels cause power loss and are heated according to overlapping state of the panels. 
     SUMMARY OF THE INVENTION 
     The present invention provides a blind device using solar cells, which minimizes power loss. 
     Embodiments of the present invention provide blind devices using solar cells, the blind devices including: a plurality of solar cell panels; and a plurality of electric wires connecting the solar cell panels to each other in series, wherein each of the solar cell panels includes: a first electrode and a second electrode on a surface; and a bypass device short-circuiting the first and second electrodes when light is not incident to the solar cell panel. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying figures are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the figures: 
         FIG. 1  is a schematic view illustrating an interconnection structure of solar cell panels and a current flow according to embodiments of the present invention; 
         FIG. 2  is a cross-sectional view illustrating a blind device using solar cells, according to an embodiment of the present invention; 
         FIG. 3  is a cross-sectional view illustrating a blind device using solar cells, according to another embodiment of the present invention; 
         FIG. 4  is a cross-sectional view illustrating a blind device using solar cells, according to another embodiment of the present invention; 
         FIG. 5  is a cross-sectional view illustrating a blind device using solar cells, according to another embodiment of the present invention; and 
         FIGS. 6 through 8 , and  FIGS. 9A and 9B  are schematic views illustrating applications of blind devices using solar cells, according to embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals refer to like elements throughout. 
     In the following description, the technical terms are used only for explain a specific exemplary embodiment while not limiting the present invention. The terms of a singular form may include plural forms unless referred to the contrary. The meaning of “include,” “comprise,” “including,” or “comprising,” specifies a property, a region, a fixed number, a step, a process, an element and/or a component but does not exclude other properties, regions, fixed numbers, steps, processes, elements and/or components. 
     Additionally, the embodiment in the detailed description will be described with sectional views and/or plan views as ideal exemplary views of the present invention. In the figures, the dimensions of layers and regions are exaggerated for clarity of illustration. Areas exemplified in the drawings have general properties, and are used to illustrate a specific shape of a device. Thus, this should not be construed as limited to the scope of the present invention. 
     Hereinafter, a blind device using solar cells according to the embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a schematic view illustrating an interconnection structure of solar cell panels  12  and  13  of a blind device according to an embodiment of the present invention. Referring to  FIG. 1 , the solar cell panels  12  and  13  include a plurality of solar cells  10 . The solar cell panels  12  and  13  connect the solar cells  10  in series to generate large solar energy. The solar cell panels  12  and  13  are connected to external terminals  1  through electric wires  20  to supply energy generated from the solar cell panels  12  and  13  to an external device (not shown). 
     The solar cell  10  includes an n-type semiconductor and a p-type semiconductor that are attached to each other. When light is incident to the solar cell  10 , the light is absorbed around a p-n junction interface to generate electron-hole pairs. Then, holes are moved to the p-type semiconductor, and electrons are moved to the n-type semiconductor through a built-in electric field, so as to generate a current. The current generated in the solar cell  10  receiving light flows through the solar cells  10 . For example, the solar cell  10  may include one of silicon, cadmium telluride, copper indium gallium selenide (CIGS), copper indium selenide (CIS), gallium arsenide, optical absorption dyes, and organic semiconductors. 
     The blind device according to the current embodiment includes the solar cell panels  12  and  13 . The solar cell panels  12  and  13  may include a generating panel (which is also denoted by  12 ) that receives light, and a non-generating panel (which is also denoted by  13 ) that does not receive light. Each of the solar cell panels  12  and  13  may include a bypass device to bypass the non-generating panel  13 . 
       FIG. 2  is a cross-sectional view illustrating a blind device using solar cells according to an embodiment of the present invention. 
     Referring to  FIG. 2 , the blind device according to the current embodiment includes the solar cell panels  12  and  13 , and the electric wires  20  electrically connecting the solar cell panels  12  and  13 . 
     The solar cell panels  12  and  13  may be attached to plastic blind slats, or may constitute blind slats, respectively. Each of the solar cell panels  12  and  13  includes a bypass device  24  and first and second electrodes  21  and  22  that are spaced apart from each other on the front side of each of the solar cell panels  12  and  13 . According to the current embodiment, conductive patterns functioning as the bypass devices  24  are disposed on the back sides of the solar cell panels  12  and  13 . 
     The solar cell panels  12  and  13  are connected to each other in series through the electric wires  20 . That is, the electric wires  20  may connect the first electrode  21  of one of the solar cell panels  12  and  13  to the second electrode  22  of another of the solar cell panels  12  and  13 . The electric wires  20  may adjust the distances and the angles between the solar cell panels  12  and  13  to adjust the amount of incident light. 
     According to the current embodiment, the first and second electrodes  21  and  22  are embedded in the solar cell panels  12  and  13 , and thus, their surfaces are flush with surfaces of the solar cell panels  12  and  13 . According to the current embodiment, the first and second electrodes  21  and  22  may protrude to be reliably in contact with the conductive patterns functioning as the bypass devices  24 . 
     When the solar cell panels  12  and  13  adjacent to each other are in contact with each other, the conductive patterns functioning as the bypass devices  24  short-circuits the first and second electrodes  21  and  22  of the non-generating panel  13  that does not receive light. That is, when the generating panel  12  is in contact with the non-generating panel  13 , the generating panel  12  may cover a surface of the non-generating panel  13 . The conductive pattern of the generating panel  12  may short-circuit the first and second electrodes  21  and  22  of the non-generating panel  13 . The conductive pattern, which is formed of conductive material, may be adhered to the back sides of the solar cell panels  12  and  13  through insulating adhesives  23 . Alternatively, the conductive pattern may be formed of conductive material having low resistance. 
     When light is incident to the solar cell panels  12  and  13  spaced apart from each other, the respective solar cell panels  12  and  13  generate electricity that flows to the external terminal  1  along the solar cell panels  12  and  13 . 
     When the solar cell panels  12  and  13  adjacent to each other are in contact with each other, the non-generating panel  13 , which is not exposed to light, does not generate electricity. At this point, the first and second electrodes  21  and  22  of the non-generating panel  13  are in contact with the conductive pattern  24  of the generating panel  12  to cause a short circuit. That is, the first and second electrodes  21  and  22  of the non-generating panel  13 , and the conductive pattern  24  attached to the back side of the generating panel  12  form a bypass. Thus, according to the current embodiment, a generated current may bypass the non-generating panel  13  to flow to the external terminal  1 . 
     That is, since the blind device according to the current embodiment includes a bypass bypassing the non-generating panel  13  through physical contact between the solar cell panels  12  and  13 , a contact point having a sufficiently low resistance value is formed between the first and second electrodes  21  and  22 . Accordingly, resistance increase due to a current path through the non-generating panel  13  can be prevented, and current bypass through the conductive pattern  24  can reduce voltage drop, relative to current bypass through a diode. Thus, loss of energy generated at the solar cell panels  12  and  13  is reduced to improve the generating efficiency of the solar cells. 
       FIG. 3  is a schematic view illustrating a blind device using solar cells, according to an embodiment of the present invention. 
     Referring to  FIG. 3 , mechanical switches  30  as bypass devices are provided to the solar cell panels  12  and  13 , respectively. 
     Each of the solar cell panels  12  and  13  includes the first and second electrodes  21  and  22  spaced apart from each other, and the mechanical switch  30  on a surface. For example, the mechanical switch  30  may be a push switch including a push button. The solar cell panels  12  and  13  are connected to each other in series through the electric wires  20 . That is, the first electrode  21  of the generating panel  12  may be connected to the second electrode  22  of the non-generating panel  13  through the electric wire  20 . 
     The electric wires  20  may adjust the distances and the angles between the solar cell panels  12  and  13  to adjust the amount of incident light. 
     The mechanical switches  30  may be turned on/off according to physical pressure generated by contact between the solar cell panels  12  and  13  adjacent to each other. The mechanical switch  30  between the first and second electrodes  21  and  22  of the solar cell panels  12  and  13  is connected in series to the first and second electrodes  21  and  22 . The mechanical switches  30  are turned on by pressing force generated when the adjacent solar cell panels  12  and  13  are in contact with each other. When the adjacent solar cell panels  12  and  13  are spaced apart from each other, the pressing force is removed, so that the mechanical switches  30  are turned off. 
     The mechanical switches  30  are embedded in the solar cell panels  12  and  13 , and thus, their surfaces are flush with surfaces of the solar cell panels  12  and  13 . Alternatively, the mechanical switches  30  may protrude from the surfaces of the solar cell panels  12  and  13  such that the mechanical switches  30  are reliably in contact with the solar cell panels  12  and  13 . Since the mechanical switches  30  have no conductive material exposed to the outside, external contamination, short circuits, and electric shocks are reduced. 
     According to the current embodiment, when light is incident to the solar cell panels  12  and  13  in the state where the solar cell panels  12  and  13  are spaced apart from each other, the solar cell panels  12  and  13  generate electricity. A generated current flows to the external terminal  1  along the solar cell panels  12  and  13  that are connected in series. When the solar cell panels  12  and  13  are in contact with each other, the non-generating panel  13  that is not exposed to light does not generate electricity, and the mechanical switch  30  is turned on by the contact between the solar cell panels  12  and  13 . Accordingly, the first electrode  21 , the mechanical switch  30 , and the second electrode  22  form a bypass in the non-generating panel  13 . 
       FIG. 4  is a schematic view illustrating a blind device using solar cells, according to another embodiment of the present invention. 
     Referring to  FIG. 4 , the blind device according to the current embodiment includes a bypass device  40  including a magnet switch  42  and a permanent magnet  44  on each of the solar cell panels  12  and  13 . The magnet switch  42  reduces troubles due to repeated on/off operations of a switch, and inaccurate operations. 
     More particularly, each of the solar cell panels  12  and  13  includes, on its front side, the first and second electrodes  21  and  22  that are spaced apart from each other. The permanent magnet  44 , generating a magnetic field having a predetermined intensity, may be attached to a surface of each of the solar cell panels  12  and  13 , and the magnet switch  42  may be attached to another surface thereof. The magnet switch  42  may be disposed at an end portion of each of the solar cell panels  12  and  13 , and the permanent magnet  44  may be disposed at another end portion thereof. The magnet switch  42  of one of the solar cell panels  12  and  13  adjacent to each other may face the permanent magnet  44  of another one. 
     The solar cell panels  12  and  13  may be connected to each other in series through the electric wires  20 . That is, the first electrode  21  of the generating panel  12  is connected to the second electrode  22  of the non-generating panel  13  through the electric wire  20 . 
     The magnet switch  42  has a structure in which a contact point is short circuited in a magnetic field and a current flows through the contact point. The region of the contact point is sealed to prevent the ingress of foreign substances. The magnet switch  42  is operated just by bring the solar cell panels  12  and  13  closer to each other without applying physical pressure. When the distance between the solar cell panels  12  and  13  is less than a predetermined value, the magnet switch  42  may form a bypass between the first and second electrodes  21  and  22  of the non-generating panel  13 . 
     The permanent magnet  44  generates a magnetic field having a sufficient intensity for operating the magnet switch  42  adjacent to the permanent magnet  44 . The permanent magnet  44  may include a magnetic field shielding member to prevent the magnetic field generated in the permanent magnet  44  from operating the irrelevant magnet switch  42  through the solar cell panels  12  and  13 . The permanent magnets  44  of adjacent ones of the solar cell panels  12  and  13  are disposed on different vertical lines or different horizontal lines to prevent malfunctions of the magnet switches  42 . In other words, the permanent magnets  44  of odd-numbered ones of the solar cell panels  12  and  13  may be disposed on first end portions of the solar cell panels  12  and  13 , and the permanent magnets  44  of even-numbered ones of the solar cell panels  12  and  13  may be disposed on second end portions of the solar cell panels  12  and  13 . 
     The permanent magnets  44  and the magnet switches  42  may be embedded in the solar cell panels  12  and  13 , and thus, their surfaces are flush with surfaces of the solar cell panels  12  and  13 . Alternatively, the permanent magnets  44  and the magnet switches  42  may protrude from the surfaces of the solar cell panels  12  and  13 . 
     The solar cell panels  12  and  13  are connected to each other in series through the electric wires  20  that may adjust the distances and the angles between the solar cell panels  12  and  13 . 
     According to the current embodiment, when light is incident to the solar cell panels  12  and  13  in the state where the solar cell panels  12  and  13  are spaced apart from each other, the solar cell panels  12  and  13  generate electricity. Generated currents flow to the external terminal  1  along the solar cell panels  12  and  13  that are connected in series. 
     When the solar cell panels  12  and  13  are in contact with each other, the non-generating panel  13  that is not exposed to light does not generate electricity, and the magnet switch  42  of the non-generating panel  13  is turned on by the permanent magnet  44  of the generating panel  12 . Accordingly, the first electrode  21 , the magnet switch  42 , and the second electrode  22  form a bypass in the non-generating panel  13 . 
       FIG. 5  is a schematic view illustrating a blind device using solar cells, according to another embodiment of the present invention. 
     Referring to  FIG. 5 , the blind device according to the current embodiment includes passive devices  52  and electrical switches  54 , as bypass devices, at the solar cell panels  12  and  13 . That is, according to the current embodiment, bypass devices  50  each may include the passive device  52  sensing light to control the operation of the electrical switch  54 , and the electrical switch  54  controlled by the passive device  52 . 
     In particular, the passive devices  52  may be photodiodes or phototransistors that use incident light to generate currents, or solar cells that are operated independently from the solar cell panels  12  and  13 . 
     The electrical switch  54  is connected in series between the first and second electrodes  21  and  22 , and is turned on/off by the passive device  52 . For example, the electrical switch  54  may be a semiconductor device such as a relay and a transistor. 
     The passive device  52  and the electrical switch  54  may be discrete devices, or be integrated in a semiconductor chip. 
     The bypass devices  50  of the solar cell panels  12  and  13  may be disposed on vertical or horizontal lines that are different from each other. That is, the bypass devices  50  of odd-numbered ones of the solar cell panels  12  and  13  may be disposed on first end portions of the odd-numbered ones, and the bypass devices  50  of even-numbered ones of the solar cell panels  12  and  13  may be disposed on second end portions of the even-numbered ones. 
     According to the current embodiment, when light is incident to the solar cell panels  12  and  13  in the state where the solar cell panels  12  and  13  are spaced apart from each other, the solar cell panels  12  and  13  generate electricity. Generated currents flow to the external terminal  1  along the solar cell panels  12  and  13  that are connected in series. 
     The solar cell panels  12  and  13  are connected to each other in series through the electric wires  20  that may adjust the distances and the angles between the solar cell panels  12  and  13 . 
     When the solar cell panels  12  and  13  are in contact with each other, light is not incident to the passive device  52  of the non-generating panel  13 . The passive device  52 , which does not receive light, turns the electrical switch  54  on to short-circuit the first and second electrodes  21  and  22  of the non-generating panel  13 . That is, the first electrode  21 , the electrical switch  54 , and the second electrode  22  form a bypass in the non-generating panel  13 . 
     The solar cell panels  12  and  13  are connected to each other in series through the electric wires  20  that may adjust the distances and the angles between the solar cell panels  12  and  13 . 
     Hereinafter, applications of blind devices  100 ,  200 ,  300 , and  400  using solar cells according to embodiments of the present invention will now be described with reference to  FIGS. 6 through 8 , and  FIGS. 9A and 9B . 
       FIG. 6  is a schematic view illustrating the blind device  100  that is horizontally disposed.  FIG. 7  is a schematic view illustrating the blind device  200  that is vertically disposed. 
     Referring to  FIG. 6 , the blind device  100  includes the solar cell panels  12  and  13  that are parallel to the ground. The solar cell panels  12  and  13  are connected to connection wires that adjust the length of the blind device  100  and the angles of the solar cell panels  12  and  13 . That is, the connection wires are adjusted to vertically move and tilt the solar cell panels  12  and  13  at a predetermined angle. In addition, the connection wires may be the electric wires  20  electrically connecting the solar cell panels  12  and  13 , and be connected to the external terminals  1 . 
     Each of the solar cell panels  12  and  13  includes the first and second electrodes  21  and  22 , and the bypass device  24 . 
     The solar cell panels  12  and  13  may be attached to surfaces of blind slats  110 , respectively. In this case, each of the solar cell panels  12  and  13  may be attached to the front surface of the blind slat  110 , and the bypass device  24  may be attached to the rear surface of the blind slat  110 . 
     When the solar cell panels  12  and  13  vertically move and cover a surface of the non-generating panel  13  disposed on the lower side, the non-generating panel  13  does not generate electrical energy. In addition, when the solar cell panels  12  and  13  vertically move, the adjacent solar cell panels  12  and  13  may be in contact with each other. Accordingly, the bypass device  24  of the generating panel  12  disposed on the upper side short-circuits the first and second electrodes  21  and  22  of the non-generating panel  13  disposed on the lower side. Thus, the current of the non-generating panel  13  flows to the generating panel  12  through the bypass device  24  without flowing through the solar cells. 
     Referring to  FIG. 7 , the blind device  200  includes the solar cell panels  12  and  13  that are vertical to the ground. The solar cell panels  12  and  13  are connected to connection wires that laterally move the solar cell panels  12  and  13  and adjust the angles of the solar cell panels  12  and  13 . The solar cell panels  12  and  13  are connected to each other in series through the electric wires  20  that may be the connection wires adjusting the positions and angles of the solar cell panels  12  and  13 . 
     When the adjacent solar cell panels  12  and  13  laterally move and overlap each other, the bypass device  24  short-circuits the first and second electrodes  21  and  22  of the non-generating panel  13  with a surface shaded from light. Thus, the current of the non-generating panel  13  flows to the generating panel  12  through the bypass device  24  without flowing through the solar cells. 
     When surfaces of the solar cell panels  12  and  13  are shaded from light, currents flow through the first and second electrodes  21  and  22  and the bypass devices  24  connected in series, without flowing through the solar cell panels  12  and  13  having the surfaces shaded from light. 
       FIG. 8  is a schematic view illustrating the blind device  300  that is collapsible. 
     Referring to  FIG. 8 , the solar cell panels  12  and  13  of the collapsible blind device  300  may be completely opened when in use, and the solar cell panels  12  and  13  may overlap each other when not is use or partially in use. 
     The collapsible blind device  300  may include a plurality of blind slats  310  having outer surfaces to which the solar cell panels  12  and  13  are attached. The blind slats  310  adjacent to each other are connected to each other such that light incident surfaces of the solar cell panels  12  and  13  face each other. 
     The outer surfaces of the solar cell panels  12  and  13  are provided with the first and second electrodes  21  and  22  that are spaced apart from each other. Further, the outer surfaces of the solar cell panels  12  and  13  are provided with the bypass devices  24  that correspond to the first and second electrodes  21  and  22 . That is, the first and second electrodes  21  and  22  of one of the solar cell panels  12  and  13  may face the bypass device  24  of the adjacent one of the solar cell panels  12  and  13 . 
     When the blind slats  310  are opened, light is incident to the solar cell panels  12  and  13  of the collapsible blind device  300  to generate currents that flow to the external terminal  1  along the solar cell panels  12  and  13  connected in series. 
     When the blind slats  310  are collapsed, the bypass devices  24  short-circuit the first and second electrodes  21  and  22  of the adjacent solar cell panels  12  and  13 , and currents generated from the generating panels  12  receiving light flow to the external terminal  1  through the bypass devices  24 . 
       FIGS. 9A and 9B  are schematic views illustrating the blind device  400  that is a roll type blind device. 
     Referring to  FIGS. 9A and 9B , the blind device  400  includes a blind sheet  410  formed of flexible plastic or flexible fabric, and the solar cell panels  12  and  13  are attached to a surface of the blind sheet  410 . A roller  420  is rotated to roll the blind sheet  410  up or down. The blind device  400  may include control wires to roll the blind sheet  410  up and down. The control wires may be the electric wires  20  connecting the solar cell panels  12  and  13  in series. 
     Each of the solar cell panels  12  and  13  includes the first and second electrodes  21  and  22 , and the bypass device  24 , and may be flexible to be rolled up together with the blind sheet  410 . 
     When the blind sheet  410  is fully rolled down, light is incident to all of the solar cell panels  12  and  13  to generate currents that flow to the external terminal  1  along the solar cell panels  12  and  13  connected in series. 
     When the blind sheet  410  is partially rolled up, light is not incident to the non-generating panel  13  wound around the roller  420 , and the vertically adjacent solar cell panels  12  and  13  may overlap each other. That is, the bypass device  24  short-circuits the first and second electrodes  21  and  22  of the non-generating panel  13  wound around the roller  420 . Accordingly, currents generated from the solar cell panels  12  and  13  receiving light flow to the external terminal  1  through the bypass devices  24 , without flowing through the non-generating panel  13 . 
     According to the embodiments of the present invention, each of the solar cell panels constituting the blind device includes the bypass device to electrically connect only the generating panels receiving light to each other, thereby preventing power loss due to the non generating panels shaded from light. 
     The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.