Patent Publication Number: US-2005139256-A1

Title: Solar cell assembly for use in an outer space environment or a non-earth environment

Description:
BACKGROUND  
      Solar cell panels have been used to generate electricity from sunlight. Further, solar cells and solar cell panels comprising a plurality of solar cells have been used in Earth and non-Earth applications when access to other electrical power sources is limited.  
      In particular, space satellites, spacecraft, and other devices used in non-Earth applications have utilized solar cell panels to provide power from sunlight for powering devices, such telecommunication devices. For purposes of discussion, the term “outer space” means space outside of the Earth&#39;s atmosphere. Further, the term “non-Earth application” means any device or system that is designed to function in outer space or on an extraterrestrial body such as a moon or a planet.  
      Photons that contact the solar cell panels directly generate electrical energy, wherein other photons only generate heat energy that remains unused. A problem associated with solar cell panels used in a non-Earth environment is that the panels often reach temperatures in excess of a desired operating temperature that decreases the electrical conversion efficiency of the solar cell panels. This occurs in part, because in space there is no atmosphere to allow thermal convection to cool the solar cell panels and to protect the solar cell panels from undesirable radiation in space.  
      Accordingly, it is desirable to provide a solar cell assembly that can be utilized in a space environment or a non-Earth environment wherein excess heat energy is capable of being radiated away from the solar cell assembly in order to maintain a temperature of the solar cell assembly within an optimal temperature operating range.  
     SUMMARY  
      A solar cell assembly for use in an outer space environment or a non-Earth environment is provided. The solar cell assembly includes a photovoltaic conversion layer configured to produce an electrical current when receiving photons on a first side of the photovoltaic conversion layer. The solar cell assembly further includes a thermally conductive layer thermally coupled to a second side of the photovoltaic conversion layer. Finally, the solar cell assembly includes a heat radiating layer coupled to the thermally conductive layer to radiate heat energy from the photovoltaic conversion layer.  
      A method for controlling a temperature of a solar cell assembly used in an outer space environment or a non-Earth environment is provided. The assembly includes a first side and a second side opposite the first side. The method includes receiving a plurality of photons on the first side of the solar cell assembly. The method further includes converting energy from a first portion of the plurality of photons into electrical energy. Finally, the method includes radiating heat energy from the second side of the solar cell assembly using a radiating layer thermally coupled to the second side.  
      Other systems and/or methods according to the embodiments will be or become apparent to one with skill in the art upon review of the following drawings and detailed description. It is intended that at all such additional systems and methods be within the scope of the present invention, and be protected by the accompanying claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  illustrates a space satellite having solar cell panels;  
       FIG. 2  is a top plan view of a solar cell array having a plurality of solar cell assemblies;  
       FIG. 3  is an enlarged portion of a solar cell assembly of the solar cell array of  FIG. 2 ;  
       FIG. 4  is another enlarged portion of a solar cell assembly of the solar cell array of  FIG. 2 ;  
       FIG. 5  is a cross-sectional view of a portion of a solar cell assembly constructed in accordance with an exemplary embodiment of the present invention;  
       FIG. 6  is a view illustrating layers of a solar cell assembly constructed in accordance with an exemplary embodiment of the present invention;  
       FIG. 7  is a cross-sectional view of a portion of a solar cell assembly constructed in accordance with another exemplary embodiment of the present invention;  
       FIG. 8  is a cross-sectional view of a portion of a solar cell assembly constructed in accordance with still another exemplary embodiment of the present invention;  
       FIG. 9  is a bottom view of the solar cell array of  FIG. 2 ;  
       FIG. 10  is a flowchart illustrating portions of a method for manufacturing solar cell assemblies in accordance with exemplary embodiments of the present invention;  
       FIG. 11  is an illustration of an expanding thermal plasma deposition system used for manufacturing exemplary embodiments of the present invention;  
       FIG. 12  is a graph illustrating the operating efficiency of a solar cell assembly versus a temperature of the solar cell assembly; and  
       FIG. 13  is a graph illustrating the temperature of a solar cell assembly versus the thickness of an emissivity layer in the solar cell assembly.  
    
    
     DETAILED DESCRIPTION  
      Referring generally to  FIG. 1 , a telecommunications satellite  10  is illustrated. Satellite  10  is provided to illustrate just one possible use of exemplary embodiments of the present invention. Satellite  10  is designed for use in non-Earth applications such as being placed in orbit around Earth for use in applications known to those skilled in the art of satellites and spacecraft. In order to provide power to the satellite, solar panels  12  and  14  are provided and positioned to face the sun in order to generate, store and use power. In accordance with an exemplary embodiment of the present invention, the solar cells and/or solar cell panels comprising a plurality of solar cells for use in any non-Earth application are constructed in accordance with the teachings disclosed herein. In particular, each of the solar panels includes a solar cell array  16 , shown in  FIG. 2 , for powering the satellite. It should be noted that solar panels  12  and  14  could be utilized with any device or system (e.g., spacecraft, space lab) in a non-Earth environment for generating electricity to power the device or system.  
      Referring now to  FIG. 2 , each solar cell array  16  includes a plurality of solar cell assemblies electrically coupled together. The number of solar cell assemblies is not intended to be limited, the number and configuration of which will depend on the intended application. For exemplary purposes, solar cell assemblies  18 ,  20 ,  22 ,  24 ,  26 , and  28  are illustrated. The design of the various solar cell assemblies are substantially the same and electrically coupled to one another in a similar manner.  
      Referring to  FIGS. 3-5 , a solar cell assembly is illustrated. Each solar cell assembly, (e.g.,  18 ,  20 ,  22 ,  24 ,  26 , and  28 ) in the array  16  generally includes a stainless steel substrate  30 , a solar cell  32  including a photovoltaic conversion, an internal grid line  34 , electrical contacts  36 ,  38 , a flexible substrate  40 , a heat radiating layer  42 , an emissivity layer  44 , a transparent electrically conductive layer  46 , a self-cleaning layer  48 , and isolation barriers  50 ,  52 . It should be noted that each of the foregoing components that form the solar cell assembly are configured to be substantially flexible as well as being capable of holding a particular configuration after being manipulated or bent. This is particularly useful for space or non-Earth applications wherein the solar cell array is constructed, manipulated into a smaller configuration for storage during transportation into space and then un-furled into a deployed state or configuration for generating power once the solar cell assembly is deployed into space. For example, solar cell assembly  18  can be configured to be rolled-up or manipulated into a smaller configuration (e.g., cylindrical roll or other configuration having a diameter or outer configuration of about 1 inch inner or greater). The aforementioned dimensions are merely provided as examples and are not intended to limit the scope of the present invention. Accordingly, solar cell assembly  18  is configured to be flexibly manipulated, and hold its manipulated shape or an unfurled shape (e.g., rolled and un-rolled).  
      As shown, stainless steel substrate  30  is disposed over an aperture  54  extending through substrate  40 . In particular, an area of stainless steel substrate  30  can be greater than an area of aperture  54  so that the stainless steel substrate  30  can be fixedly attached to a surface  41  of substrate  40  over aperture  54 . Stainless steel substrate  30  can be fixedly attached to surface  41  using a high-temperature glue, for example. Further, stainless steel substrate  30  can have a thickness of about 5 millimeters (mm) so as to provide considerable flexibility therein. Substrate  30  could be constructed with a thickness less than or greater than about 5 mm depending upon a desired flexibility or a desired thermal conductivity of stainless steel substrate  30 . The particular configurations illustrated in  FIGS. 3-5  are provided as examples and the present invention is not intended to be limited to the specific configurations illustrated in the Figures.  
      The solar cell  32  is provided to generate an electrical current in response to photons contacting solar cell  32 . Solar cell  32  is fixedly attached to stainless steel substrate  30 . As shown more clearly in  FIG. 3 , solar cell  32  includes a photovoltaic conversion layer  33 , an electrical contact layer  36  constructed from indium tin oxide on an upper surface of layer  33 , and an electrical contact reflector layer  33  constructed from silver or zinc oxide on a bottom surface of layer  33 . Electrical contact layer  36  is electrically coupled to contact  38  disposed on an isolation barrier  52 . When photons contact photovoltaic conversion layer  33  a voltage potential is created between layers  33 ,  35 . Referring to  FIG. 6 , photovoltaic conversion layer  33  can comprise a plurality of sub-layers. In particular, photovoltaic conversion layer  33  may comprise: (i) a p3 sub-layer comprising a P-type semiconductor sub-layer, (ii) an i3 sub-layer comprising an intrinsic semi-conductor sub-layer, (iii) an n3 sub-layer comprising a N-type semiconductor sub-layer, (iv) a p2 sub-layer comprising a P-type semiconductor sub-layer, (v) an i2 sub-layer comprising an intrinsic semiconductor sub-layer, (vi) an n2 sub-layer comprising a N-type semiconductor sub-layer, (vii) a p1 sub-layer comprising a P-type semiconductor sub-layer, (viii) an i1 sub-layer comprising an intrinsic semi conductor sub-layer, and a (ix) an n1 sub-layer comprising a N-type semiconductor sub-layer.  
      Referring to  FIG. 12 , a graph illustrating an operating efficiency of a solar cell  32  versus a temperature of the solar cell is illustrated. In particular, line  134  represents the efficiency of solar cell  32  and a line  132  represents the temperature of solar cell  32 . The intersection point  135  of line  132  and line  134  represents one desired operating temperature for solar cell  32 . As shown, the desired temperature is approximately 85° C. in this embodiment. Accordingly, solar cell  32  can most efficiently produce electricity when solar cell  32  has an internal temperature range between 50° C. and 110° C. Further, both emissivity layer  44  and heat radiating layer  42  are utilized for maintaining a temperature of solar cell  32  within a desired temperature range.  
      Referring to  FIGS. 2 and 4 , grid line  34  is provided to collect and conduct electrons flowing through solar cell  32 . As shown grid line  34  is disposed on solar cell  32  and is electrically coupled to contacts  36 ,  38 . Grid line  34  can be constructed from silver (Ag) or aluminum (Al). It should be noted that although only one grid line is shown in  FIG. 4 , solar cell assembly  18  includes: (i) a plurality of upper grid lines collecting and conducting electrons flowing proximate an upper side of solar cell  32 , and (ii) a plurality of lower grid lines collecting and conducting electrons flowing proximate a lower side of solar cell  32 , as shown in  FIG. 2 . Grid line  34  is configured to be substantially flexible.  
      Referring to  FIG. 4 , emissivity layer  44  is provided to absorb a portion of energy of photons contacting layer  44  and to radiate the absorbed energy away from solar cell  32 . By radiating the absorbed energy, solar cell  32  can be maintained within an optimal temperature range. In particular, emissivity layer  44  is configured to absorb the energy from light wavelengths greater than or equal to 5 microns and to radiate the absorbed heat energy away from solar cell  32 . It should be noted that light wavelengths greater then or equal to 5 microns lack sufficient energy to break free “electron-hole” pairs in solar cell  32  to create an electrical current. Thus, any light wavelengths greater than or equal to 5 microns contacting solar cell  32  merely generate heat within solar cell  32 . Thus, emissivity layer  44  is provided to absorb and radiate the energy from light wavelengths in this undesirable wavelength range and to allow light wavelengths less than 5 microns (e.g., wavelengths between 2-800 nm) to contact solar cell  32  to generate electricity.  
      Emissivity layer  44  can have an emissivity greater than or equal to 0.8. The term “emissivity” means the relative power of a surface to emit heat by radiation, and in particular, the ratio of the radiant energy emitted by a surface to that emitted by a black body having the same area and temperature. Emissivity layer  44  can be constructed from silicon oxides such as SiO 2 , silicon nitrides such as Si 3 N 4 , silicon oxynitrides, silicon oxycarbides, silicon carbides, silicon nitrocarbides, silicon oxynitrocarbides, and the like. Further, emissivity layer  44  can have a thickness of 10 microns or greater and may be disposed over substantially an entire top surface of solar cell array  16 . An example of a suitable emissivity layer and a method of making the emissivity layer is found in International Application WO 01/75486 A2.  
      It should be noted that as space satellites orbit the Earth, the satellites come into contact with electrons floating through space. In particular, solar panel assemblies, e.g.,  18 ,  20 ,  22 ,  24 ,  26 , and  28 , on the satellites come into contact with the electrons that adhere to an outer surface of the solar panel assemblies. After a significant amount of electrons adhere to the solar panel assemblies, an electro-static discharge can occur through solar cells in the solar panel assemblies that can damage the solar cells therein.  
      The transparent electrically conductive layer  46  is provided to capture electrons that are traveling in space that contact the solar panel assemblies. The transparent electrically conductive layer  46  conducts the electrons away from the solar cell  32  to prevent electro-static discharge therein. Conductive layer  46  can be constructed from indium tin oxide (ITO) or zinc oxide. Conductive layer  46  is preferably disposed over emissivity layer  44  at a thickness of about 30 to about 100 nanometers (nm) and may be disposed over substantially the entire top surface of the solar cell array  16 . Conductive layer  46  also reflects light wavelengths greater than or equal to 5 microns contacting layer  46  away from solar cell  32 . Layer  46  is configured to be substantially flexible.  
      In the illustrated embodiment, self-cleaning layer  48  is provided to remove dust or dirt that can adhere to solar cell array  16  when satellite  10  is at a relatively low Earth orbit. Self-cleaning layer  48  can be disposed over layer  46  and may comprise a layer of titanium dioxide (TiO 2 ) that is substantially flexible. While not wanting to be bound by theory, it is believed that the self-cleaning layer  48  attracts water particles, such as may be present at low Earth orbits, which then moves underneath any dust or dirt contacting layer  48  so that the dust or dirt will no longer bond to layer  48 . Thereafter, as satellite  10  moves through space, the dust and dirt floats off of layer  48 . It should be noted that in an alternate embodiment of assembly  18  (not shown), self-cleaning layer  48  could be removed from the assembly.  
      It should be noted that on known solar cell assemblies, the solar cell assemblies are mounted on a rigid frame for holding the various components of the assemblies. Thus, the solar cell assemblies are not flexible. Further, the rigid frames are relatively heavy which results in relatively high costs to transport the solar cell assemblies from Earth to an outer space environment or a non-Earth environment. Further, because the solar cell assemblies cannot be rolled-up, a relatively large transport vehicle (e.g., rocket) having a large cargo area must be utilized to transport the known solar cell assemblies from Earth to an outer space environment or a non-Earth environment.  
      Referring to  FIGS. 2, 4 , and  8 , flexible substrate  40  is provided to support solar cell assemblies  18 ,  20 ,  22 ,  24 ,  26 ,  28  and is configured to be rolled-up for transport into a space environment or a non-Earth environment. As shown, substrate  40  includes apertures  54 ,  56 ,  58 ,  60 ,  62 ,  64  extending therethrough. Further, solar cell assemblies  18 ,  20 ,  22 ,  24 ,  26 ,  28  are disposed on one side of substrate  40  over apertures  54 ,  56 ,  58 ,  60 ,  62 ,  64 , respectively. As shown, a periphery of each of solar cell assemblies  18 ,  20 ,  22 ,  24 ,  26 ,  28  is larger than a periphery of each of apertures  54 ,  56 ,  58 ,  60 ,  62 ,  64  respectively. Solar cell assemblies  18 ,  20 ,  22 ,  24 ,  26 ,  28  include radiating layers  42 ,  72 ,  74 ,  76 ,  78 ,  80  extending through apertures  54 ,  56 ,  58 ,  60 ,  62 ,  64 , respectively, to conduct heat energy away from the assemblies.  
      Flexible substrate  40  can be constructed from a thermally non-conductive polyimide identified by the trademark “KAPTON H” or the trademark “KAPTON E”, manufactured by DuPont Corporation. Because the KAPTON® product is a thermally non-conductive polyimide, the inventors herein have recognized that the heat radiating layers can be disposed through the KAPTON® layer  40  to radiate excess heat generated in solar cell  32  (and the other solar cells in solar cell array  16 ) from a backside of solar cell array  16 .  
      In alternate embodiments, substrate  40  can be constructed from films of one or more of the following materials: (i) polyethyleneterephthalate (“PET”), (ii) polyacrylates, (iii) polycarbonate, (iv) silicone, (v) epoxy resins, (vi) silicone-functionalized epoxy resins, (vii) polyester such as polyester identified by the trademark “MYLAR” manufactured by E.I. du Pont de Nemours &amp; Co., (viii) a material identified by the trademark “APICAL AV” manufactured by Kanegaftigi Chemical Industry Company, (ix) a material identified by the trademark “UPILEX” manufactured by UBE Industries, Ltd.; (x) polyethersulfones “PES,” manufactured by Sumitomo, (xi) a polyetherimide identified by the trademark “ULTEM” manufactured by General Electric Company, and (xii) polyethylenenaphthalene (“PEN”).  
      In other alternate embodiments, substrate  40  can be constructed from stainless steel. The stainless steel may have an insulating coating or may not have an insulating coating depending upon desired thermal characteristics of substrate  40 . Alternately, flexible substrate  40  can be constructed from a relatively thin glass that is reinforced with a polymeric coating, such as a glass manufactured by Schott Corporation, for example.  
      Referring to  FIG. 4 , heat-radiating layer  42  is provided to radiate excess heat away from solar cell  32  to maintain an optimal operating temperature range of solar cell  32 . As shown, layer  42  is operably coupled to stainless steel substrate  30 . Because substrate  30  is thermally conductive, excess heat energy from solar cell  32  is conducted through stainless steel layer  32  to heat radiating layer  42 . Thereafter, heat-radiating layer  40  to radiates the excess heat energy into space. Heat radiating layer  42  can comprise a black body radiating layer. In particular, layer  42  can comprise a layer of chromium oxide applied through aperture  54  to a bottom surface of stainless steel substrate  30 . As shown, heat- radiating layer  42  may have a thickness substantially equal to the thickness of flexible substrate  40 . In an alternate embodiment, a second stainless steel substrate (not shown) could be fixedly attached between substrate  30  and heat radiating layer  42 .  
      The isolation barriers  50 ,  52  are provided to electrically isolate contacts  36 ,  38 , respectively, in assembly  18 . It should be noted that solar cell assembly  18  includes a plurality of such isolation barriers. In particular, each electrical contact proximate an upper surface of solar cell assembly  18  is coupled to a corresponding isolation barrier. Further, each electrical contact proximate a lower surface of solar cell assembly  18  is coupled to a corresponding isolation barrier.  
      Referring to  FIG. 13 , a graph illustrating the operating temperature of solar cell assembly  18  is illustrated. In particular, the graph indicates that a temperature of solar cell assembly  18  can be maintained between about 80° C. and about 90° C. when utilizing emissivity layer  44  of at least 10 microns in thickness and heat radiating layer  42 . It should be noted that a temperature of solar cell assembly  18  could be maintained at a range less than or greater than 80° C.-90° C. depending on the desired operating characteristics of assembly  18 .  
      Referring to  FIG. 7 , another exemplary embodiment of a solar cell array (e.g. solar cell array  216 ) is illustrated. The primary difference between solar cell array  216  and solar cell array  16  is that solar cell array  216  has an annular recess about the aperture in flexible substrate that is configured to receive the stainless steel substrate, whereas solar cell array  16  has a stainless steel substrate that rests on top of an aperture in the flexible substrate.  
      As shown, flexible substrate  240  has an aperture  254  including aperture portions  96 ,  98 . Aperture portion  96  is configured to receive at least a portion of stainless steel substrate  30 . Aperture portion  96  has a periphery smaller than stainless steel substrate  30  such that substrate  30  rests on a ledge  100  defined by aperture portions  96 ,  98 . Aperture portion  96  is configured to receive heat radiating layer  42 .  
      Referring to  FIG. 8 , another exemplary embodiment of a solar cell array (e.g. solar cell array  316 ) is illustrated. The primary difference between solar cell array  316  and solar cell array  16  is that solar cell array  316  has emissivity layer  344 , a transparent conductive layer  346 , and a self-cleaning layer  348  that does not cover the entire top surface of solar cell array  316 . Whereas solar cell array  16  has an emissivity layer  44 , a conductive layer  46 , and a self-cleaning layer  48  that covers substantially the entire top surface of solar cell array  16 .  
      As shown, solar cell array  316  has an emissivity layer  344 , a conductive layer  346 , and a self-cleaning layer  348  that covers the solar cell assemblies (e.g., solar cell assemblies  318  and  322 ) but leaves a portion of flexible substrate  40  uncovered. As shown, flexible substrate  40  has a region  109  between solar cell assemblies  318 ,  322  that is not covered by layers  344 ,  346 ,  348 .  
      Referring to  FIG. 11 , before providing a detailed description of how a solar cell array can be made, a brief description of an expanding thermal plasma deposition system  110  that can be utilized to apply layers  44 ,  46 ,  48  to a solar cell will be explained. System  110  includes a plasma ejection device  111 , a reagent supply device  120 , and an argon supply device  126 .  
      Plasma ejection device  111  includes a body portion  112 , a nozzle portion  114 , a cathode member  115 , and a voltage supply  118 . An aperture  113  extends through body portion  112  and nozzle portion  114 . Aperture  113  is provided to allow an argon gas from argon supply device  126  to be communicated therethrough. Cathode member  115  is disposed in aperture  113 .  
      Voltage source  118  is electrically connected between cathode member  115  and nozzle portion  114 . When argon supply device  126  supplies argon gas through aperture  113 , the argon gas is electrically charged by cathode member  115 .  
      Reagent supply device  120  is provided to supply reagent compound particles that will be subsequently coated on a portion of solar array  16 . For example, reagent supply device  120  could supply one or more of: (i) silicon oxides, (ii) silicon nitrides, (iii) silicon oxynitrides, (iv) silicon oxycarbides, (v) silicon carbides, (vi) silicon nitrocarbides, (vii) silicon oxynitrocarbides—that can be used by system  110  to form emissivity layer  44  on a solar cell. Further, for example, reagent supply device  120  could supply indium tin oxide (ITO) or zinc oxide that can be used by system  110  to form transparent electrically conductive layer  46  on a solar cell. Further, for example, reagent supply device  120  could supply titanium dioxide to form self-cleaning layer  48  on a solar cell.  
      During operation of system  110  when plasma ejection device  111  is disbursing ionized argon particles and reagent supply device  120  is supplying reagent particles, the ionized argon particles attach to the reagent particles and the combined particles are directed toward a surface of solar cell array  16 . As the argon particles and reagent particles contact the surface solar cell array  16 , the reagent particles adhere to the surface of solar cell array  16 . It should be noted that system  110  has a relatively fast rate of applying a desired layer or layers to a solar cell assembly. For example, system  110  can deposit layers at greater than 1 micrometer/minute with a deposition temperature of less than 200 degrees Celsius.  
      Referring to  FIG. 10 , a method for making a solar cell array will now be described. It should be noted that the method for making the solar cell array is directed to adding the following layers: (i) emissivity layer  44 , (ii) transparent electrically conductive layer  46 , (iii) self-cleaning layer  48 , and (iv) heat radiating layer  42 —to a plurality of solar cell assemblies each including a stainless steel substrate, a solar cell, grid lines, and electrical contacts.  
      At step  130 , a plurality of solar cell assemblies are disposed on flexible substrate  40 . The solar cell assemblies are electrically coupled together with external grid lines and positioned over corresponding apertures in flexible substrate  40 .  
      At step  132 , a heat radiating layer is applied to a bottom surface of each of the plurality of solar cell assemblies through each of the corresponding apertures in flexible substrate  40 .  
      At step  134 , an emissivity layer  44  is deposited on the plurality of solar cell assemblies disposed on flexible substrate  40 . Emissivity layer  44  can be deposited on the plurality of solar cell assemblies utilizing thermal plasma deposition system  110  or a sputtering system known to those skilled in the art.  
      At step  136 , transparent electrically conductive layer  46  is deposited on emissivity layer  44 . Conductive layer  44  can be deposited on the plurality of solar cell assemblies utilizing thermal plasma deposition system  110  or a sputtering system known to those skilled in the art.  
      At step  138 , self-cleaning layer  48  can be deposited on conductive layer  46 . Self-cleaning layer  48  can be deposited on the plurality of solar cell assemblies utilizing thermal plasma deposition system  110  or a sputtering system known to those skilled in the art.  
      The solar cell assemblies and a method for controlling a temperature of the solar cell assemblies described herein represent a substantial advantage over known solar cell assemblies and methods. In particular, the solar cell assemblies are configured to radiate excess heat energy from the solar cell assemblies from the backside of the assemblies. Accordingly, an operating temperature of the solar cell assembly can be maintained within an optimal operating temperature range in a space environment or in a non-Earth environment.  
      While the invention is described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made an equivalence may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to the teachings of the invention to adapt to a particular situation without departing from the scope thereof. Therefore, is intended that the invention not be limited the embodiment disclosed for carrying out this invention, but that the invention includes all embodiments falling with the scope of the intended claims. Moreover, the use of the term&#39;s first, second, etc. does not denote any order of importance, but rather the term&#39;s first, second, etc. are us are used to distinguish one element from another. CLAIMS