Abstract:
A portable electronic device includes a housing including an outer surface and an inner surface. A core electronic component is configured to be provided inside of the housing. A transparent material is provided at the outer surface of the housing. A solar cell is provided on the inner surface of the housing and spaced apart from the transparent material by a predetermined distance. The transparent material is configured to receive light from an external source and direct the light to the solar cell.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application claims priority to U.S. Patent Application No. 60/417,302, filed on Oct. 8, 2002, which is incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a solar cell charger used in a portable device. 
     Recently, all types of electrical equipment have been miniaturized and converted to portable devices, e.g., notebook computer, personal digital assistant, mobile phone, and the like. These portable device require use of batteries for obvious reasons. A single-use batteries (e.g., dry-cell batteries) and rechargeable batteries (e.g., nickel-cadmium batteries) are well known battery power sources. 
     Today&#39;s portable electronic devices generally use rechargeable batteries for its convenience. Rechargeable batteries may be charged using alternating current (AC current) or solar energy. The alternating current requires a power socket that is connected to a power source. Accordingly, devices that use the AC currents to recharge generally cannot be used in outdoors. For this reason, it may be necessary to carry a spare battery if the portable device is to be used for extended time away from a power source. 
     Rechargeable solar energy batteries, however, can be charged generally anywhere, both indoors or outdoors, as long as there is light, thereby providing a greater flexibility to users. In addition, solar-cell batteries do not require any AC current conversion circuitry since only direct current is used, which simplifies circuitry and reduces manufacturing cost. 
     A typical solar cell based charger includes a solar cell, namely a photovoltaic device, batteries, associated electrical circuits, and the casing of the assembly. The solar cell  30  is generally mounted on the side of a container  10 , as shown in  FIG. 1 . A core electronic component is provided within the container. When the core electronic component is inserted into the container via an opening  15 , its batteries are charged with electrical energy by the battery module  20  of the container  10 . The battery module  20  is charged by the solar cell  30 . The battery module  20  contains power management electronic circuitry to operate as desired in these applications. 
     In a conventional technology, a solar cell is mounted on one of the external surfaces of the container, as shown in  FIG. 1 . In order for the solar cell to capture as much sun light as possible, it is desirable to cover as much of the surfaces of the container as possible with solar cells. The solar cell  30 , having a lateral dimension of X, covers substantially all of the upper surface of the container  11  that has a lateral dimension Y. However solar cell material is more costly than the plastics, polymer, or metal that are generally used to make the container. In addition, solar cell material, especially, the semiconductor based solar cell, is brittle and may easily scratch or break in the daily handling of such a container. 
     BRIEF SUMMARY OF THE INVENTION 
     In one embodiment, a portable electronic device includes a housing including an outer surface and an inner surface. A core electronic component is configured to be provided inside of the housing. A transparent material is provided at the outer surface of the housing. A solar cell is provided on the inner surface of the housing and spaced apart from the transparent material by a predetermined distance. The transparent material is configured to receive light from an external source and direct the light to the solar cell. 
     In another embodiment, a housing for an electronic component includes an outer surface; an inner surface that is spaced apart from the outer surface by a first distance; and a light concentrator provided at the outer surface of the housing, the light concentrator including a first side and a second side. The inner surface is configured to receive a solar cell, the solar cell facing the first side of the light concentrator. The light concentrator is configured to focus light from an external source to the solar cell. 
     In yet another embodiment, a portable electronic device includes a housing including an outer surface and a lens provided at the outer surface of the housing; a solar cell component provided inside of the housing and spaced apart from the lens by a predetermined distance, the solar cell component having a smaller surface area than the lens; a battery module coupled to the solar cell component to store energy received from the solar cell; and an electronic circuit configured to perform a given function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a container to hold a portable electronic device. 
         FIG. 2 . illustrates a concept of using a light concentrator in conjunction with the a solar cell according to one embodiment of the present invention. 
         FIG. 3  illustrates a housing for a portable electronic device according to one embodiment of the present invention. 
         FIG. 4 . illustrates a top plan view of the housing of  FIG. 3  according to one embodiment of the present invention. 
         FIG. 5  illustrates a solar cell charger circuit for a portable electronic device according to one embodiment of the present invention. 
         FIG. 6  illustrates a housing for a portable electronic device according to another embodiment of the present invention. 
         FIG. 7  illustrates a housing with a curved lens for a portable electronic device according to another embodiment of the present invention. 
         FIG. 8  illustrates a housing with a skylight structure for a portable electronic device according to another embodiment of the present invention. 
         FIG. 9  illustrates a portable electronic device including a housing and an electronic component according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiments of the present invention relates to a portable electronic device that uses solar energy. A container of the portable device is provided with a smaller solar cell area without significantly compromising the energy charging capabilities of the device. The embodiments use the concept of light concentrators to reduce the size of the solar cell. 
       FIG. 2  illustrates the concept of providing an optical light concentrator or lens  40  between the incident light and a solar cell  50 . Although the solar cell  50  is illustrated as a single cell for illustrative convenience, the solar cell  50  may include a plurality of cells in series or in array. The lens  40  can be a Fresnel type lens that is flat and can be produced from transparent, low cost polymer material. The lens  40  concentrates the light on a solar cell of smaller dimension than the lens. For example, a lateral dimension Z of the lens is several times larger than a lateral dimension W of the solar cell  50 . In another embodiment, a ratio of Z to W is 1.2, 1.3, 1.5, 1.7, 1.9, 2.0, 2.5, 3.0, or greater. 
     The use of a lens requires a separation space between the lens and the solar cell according to the depth of focus (or focal distance) of the lens. That separation space is represented as H in  FIG. 2 . 
       FIG. 3  illustrates a portable electronic device  100  according to one embodiment of the present invention. The device  100  may be a phone, personal digital assistant, calculator, or the like. The device  100  includes a core electronic component  102  and a portable electronic device container  160 . A solar cell  151  is provided inside the container and facing a lens  140 . The lens is formed on an outer surface of the container  160 . The lens concentrates light onto the solar cell. The lens is a distance H1 away from the solar cell for desired effective light concentration, thus enabling the solar cell to operate at higher conversion efficiency for charging a container battery module (battery component)  163  of the container. 
     By using a low cost lens as part of the container and a smaller size solar cell, the container may be manufactured at a lower price. In addition, by placing the solar cell inside of the container  160 , the solar cell is protected from mechanical damages due to impact or scratches resulting from daily handling of the container. A structural guide or spacer  162  are built inside of the container  160  to protect the solar cell  151  from a core electronic component  102  that may be inserted therein via an opening  165 . Other techniques can be used, like a transparent plastic barrier or layer  166  that covers fully or partially the solar cell. 
     In one embodiment, the device  100  may be used while the component  102  is docked into the container or undocked from the container. That is, the core component  102  is itself a self-contained, operating electronic device. When the component  102  is docked into the container, an internal battery module  104  of the component is charged by the container battery module  163 . The component  102  may also be used while undocked from the container. The container battery module  163  may be charged during such a time.  FIG. 4  illustrates a top view of the container with the lens  140  as part of the container  161 . 
       FIG. 5  illustrates a battery charger circuit  170  of the device  100  according to one embodiment of the present invention. The circuit  170  includes a solar battery component  172  and a diode  174  for preventing a reverse flow of energy generated by the solar battery component  172 , and an overvoltage or overcurrent protection circuit  176 . A battery component  178 , e.g., lithium ion battery, stores the energy from the solar battery component  172  via the diode and protection circuit. In certain application, the protection circuit is not needed. A switch  180  is turned on to charge an internal battery component  182  that is provided within the core electronic component. In one embodiment, the docking of the core component automatically forms an electrical connection between the core component and the battery component  178 . 
       FIG. 6  illustrates a container  261  including a plurality of lens  241  and  242  and a plurality of solar cells  271  and  272  according to one embodiment of the present invention. The lenses and solar cells are separated by a distance H1. A container battery module  264  is provided inside the container. The container has an opening  265  for docking or undocking a core electronic component (not shown). The material of the lens can be optimized for the desired product in color or transparency to give it the desired graphic effect for specific consumer markets. 
       FIG. 7  illustrates a container  361  including a contoured or curved lens  343  according to one embodiment of the present invention. Light is focused onto a solar cell  373 . In this embodiment, a lateral dimension of the lens is greater than a lateral dimension of the solar cell. 
       FIG. 8  illustrates a container  466  for use in larger electronic instruments or equipment according to one embodiment of the present invention. The container surface can be structured like a “skylight” with part of it shaped as a lens  444  of desired configuration. Only a portion of the area that receives light may be provided with a solar cell  474  if the remaining portion of the entire area is needed for other uses, e.g., for various electronic components of the electric equipment. Portions  445  and  446  of the container  466  are also made of a transparent material but are not used as lenses in this embodiment. These portions are merely used as skylights to provide illumination to an area  469  that is part of the internal cavity of the container  466 . A container battery module  468  is provided inside the container to store the energy generated by the solar cell  474 . 
       FIG. 9  illustrates an portable electronic device  500  including a housing  502  and an electronic component  504  according to one embodiment of the present invention. The housing includes a lens  506  provided on an outer surface of the housing and a divider  510  provided inside the housing. The divider  510  separates the housing into two compartments: a solar cell compartment  512  and a main compartment  514 . The solar cell compartment  512  includes a solar cell  508  that is provided below the lens  506 , separated by an optimum distance H1 for focusing light onto the solar cell. A housing battery module  516  is provided within the solar cell compartment. In other applications, the battery module  516  may be provided in the main compartment. 
     The main compartment  514  stores the electronic component  504  that performs core functions of the device  500 . The electronic component  504  is configured to be docked into or undocked from the main compartment in the present embodiment. When the component is docked into the compartment, an internal battery module  518  provided inside of the electronic component  504  couples to the housing battery module to receive energy from the housing battery module. 
     In another embodiment, the electronic component  504  is securely attached to the housing  502 , so that the device  500  is configured to be used with the component  504  provided inside of the housing. In such an embodiment, the device  500  may not require the internal battery module  518  or the divider  510 , or both. 
     The present invention has been described in terms of the specific embodiments above. These embodiments are used merely to illustrate the invention and may be modified or altered without departing from the scope of the present invention. Accordingly, the scope of the invention is defined using the appended claims.