Abstract:
A photovoltaic illuminating device, comprising solar cell, electronic circuit, two rechargeable batteries, an illuminating means and a display frame to illuminate during nighttime a house&#39;s street address numerals on a roadside mailbox or its supporting post, using solar energy collected and stored in the rechargeable batteries during daytime, is disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from US Provisional Application Ser. No. 60/531,272, filed on Dec. 22, 2003, and the contents of which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Technical Field of the Invention  
         [0003]     Our present invention pertains to a photovoltaic illuminating device for a street address number on a roadside mailbox. In particular, the stand-alone device can be easily installed onto an existing mailbox or its post. It employs one thin-plate solar cell to absorb solar energy during daytime, and one or two light-emitting diodes (LED) to shed light to address numerals during nighttime.  
         [0004]     2. Description of Prior Art  
         [0005]     In US, Canada and other countries, the address number sign of a residential house is often labeled on the mailbox or its supporting post alongside the street in front of the house. It is a common experience that, in the evening and during nighttime, locating a specific address in a dark or poorly lighted neighborhood is oftentimes a difficult job. Fire departments across America all agree that one of their most difficult tasks in their nighttime emergency operations is to figure out which house the call has come from. Our present invention has been developed to solve this problem.  
         [0006]     Our reference search has revealed a few patented solar energy devices and related applications that intended to provide illuminating help for signs and other residential uses. Solar-powered illuminated mailbox address signs are disclosed in U.S. Pat. Nos. 5,460,325 and 5,522,540 to Surman, and U.S. Pat. No. 6,076,294 to Durbin.  
         [0007]     U.S. Pat. No. 5,522,540, as a Continuation-In-Part of U.S. Pat. No. 5,460,325, discloses an illuminated mailbox address assembly, and describes the mailbox structure changes required for installing the assembly. In brief, the referenced patent would require a homeowner either to adopt a new mailbox structure (for rural type mailbox) or to reconstruct an existing mailbox (for urban type mailbox) in order to install the illuminated address number assembly. In other word, replacing and restructuring the existing mailbox would be necessary for using the referenced patent.  
         [0008]     U.S. Pat. No. 6,076,294 discloses a solar-powered illuminated mailbox address plate which can be attached to one side of a mailbox. The referenced patent uses one light-emitting diode (LED) for each indicium (or digit). Thus, for an address number sign with 4 indicia, four LEDs will be used. If two address plates are needed for both side of the mailbox, 8 LEDs will be needed. The referenced patent uses a solar panel and a rechargeable lead-acid battery to provide power for illuminating.  
         [0009]     Therefore, it is desirable to create a stand-alone device that uses a minimum number of LEDs, so that the device (1) allows easy installation on an existing roadside mailbox without any structural change of the mailbox itself, (2) is energy-saving and in a compact form, and (3) is practically and commercially doable and affordable. Our present invention presents such a device that does not require replacement or reconstruction of the existing mailbox. A homeowner can install this device easily at any convenient position on an existing mailbox or its supporting post.  
       SUMMARY OF THE INVENTION  
       [0010]     Generally, as provided by this invention, a photovoltaic illuminating device consists of a commercially available thin-plate solar cell, a printed circuit board (PCB), one or two rechargeable batteries, a lighting means, and an address display means. The solar cell, the PCB and the rechargeable batteries are assembled closely together within an assembly enclosure, while the lighting means and the address display means can be either separated from or integrated with the assembly enclosure.  
         [0011]     The solar cell is placed at the top of the assembly enclosure. The PCB and the rechargeable batteries are below the solar cell and within the enclosure. During daytime, the solar cell collects and converts the solar energy to electrical energy, and charges the rechargeable batteries through the PCB. When the evening comes or the ambient light becomes insufficient to see the address number, the charged batteries discharge the electrical energy to power the lighting means to illuminate the address number. A photo sensor, connected to the PCB and integrated at the edge of the solar cell plate, controls the PCB to charge the batteries during daytime and to discharge the batteries to power the illuminating means during nighttime.  
         [0012]     The enclosure is placed at the top of the mailbox or at the top the mailbox post, via adhesive means or mounting screws. Preferably, the enclosure is tilted to allow the solar cell to face the Sun&#39;s position around the noontime, thus, colleting the maximum amount of solar energy. For this purpose, the enclosure is installed on the mailbox post via two L-shaped brackets that allow two rotational adjustment of the solar cell orientation.  
         [0013]     The lighting means, preferably a light-emitting diode (LED), is connected with the rechargeable batteries via an electrical extension wire, and is connected to an address display means. Preferably, an address display means is a hollow rectangular frame with each face being a diffuser plate (such as a semi-transparent plastic plate). An LED, electrically wired from the enclosure, is located inside one end of the frame and sheds light into the hollow frame. Preferably, another so-wired LED is installed at the opposite end of the frame and sheds light into the hollow frame from an opposite direction. Individual self-adhesive numerals (digits) stick to the outer face of each diffuser plate to form the address number. The rectangular frame is in horizontal or vertical position and is attached to the mailbox or fixed to the side of the post. Preferably, the display frame stays horizontal and is placed on the top of the mailbox. Preferably, further, the afore-mentioned assembly enclosure and the display frame are integrated together to become one solid single unit that is then placed horizontally at the top of the mailbox or attached vertically to the mailbox post.  
         [0014]     Preferably, optical fiber panels are used in the hollow space within the display frame and between the two diffuser plates. Light-emitting diodes are used to serve as light sources for the optical fiber panels. Advantage of using optical fiber panels is to provide a uniform lighting background for the address numerals on the diffuser plates.  
         [0015]     Besides the intended use of the invention, which is to provide aid for visitors to identify street addresses on mailboxes, the illuminating device immediately adds a pleasant and impressive nighttime landscaping feature to any residential neighborhood. 
     
    
     BREIF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a perspective view of one embodiment of the present invention of an illuminating device for a street address number on a roadside mailbox.  
         [0017]      FIG. 2 , in a greater scale as compared to  FIG. 1 , is an exploded view of an assembly box to house a solar cell, a photo sensor, a printed circuit board (PCB), and two rechargeable batteries.  
         [0018]      FIG. 3 , in a greater scale as compared to  FIG. 1 , is a preferred address display frame and one cross-section view of the frame.  
         [0019]      FIG. 4 , in a greater scale as compared to  FIG. 1 , is an exploded view of an address display frame using optical fiber panels as lighting background.  
         [0020]      FIG. 5  is a perspective view of another embodiment showing a vertical display frame installed on a mailbox post.  
         [0021]      FIG. 6 , in a greater scale as compared to  FIG. 1 , is a perspective view of a preferred adjustable bracket to be used to install the assembly enclosure to a mailbox post.  
         [0022]      FIG. 7  is perspective view of another embodiment showing an integrated one-unit illuminating device installed on the top of a mailbox. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]     The present invention and its preferred embodiment are described in detail in this section with reference to  FIG. 1  through  FIG. 7  as listed in the previous section. As shown in  FIG. 1 , a photovoltaic illuminating device based on the present invention is mounted on an existing mailbox  1  and its post  2 . The illuminating device consists of an assembly enclosure  3  and an address display frame  4  with an address number sign  5 . The assembly enclosure  3  is installed on the mailbox post  2  via adjustable brackets  6 . A commercially available solar cell  7  is at the top of the assembly enclosure to collect solar energy during daytime. An electrical extension wire  8  is used to connect the enclosure  3  to the address display frame  4 .  
         [0024]     As shown in  FIG. 2 , a solar cell  7  sits on the top of the assembly enclosure  3 . Water-resistant glue is used to attach the solar cell  7  firmly into a sink  10  at the top of the enclosure  3 . A photo sensor  9  is imbedded at one edge of the solar cell  7 . Alternatively, the photo sensor is installed at one top edge of the enclosure  3  or other suitable locations. A printed circuit board (PCB)  11  and two small rechargeable batteries  12 , preferably Size AA batteries, are sitting inside the assembly enclosure  3 . A hole  13  at the center of the sink  10  exists to allow wiring among the solar cell  7 , the photo sensor  9 , and the PCB  11  inside the enclosure  3 . An electrical extension wire  8  from the PCB  11  comes out from the enclosure  3  through a small hole  14  to outside the enclosure to the address display frame (not shown in  FIG. 2 ). This wiring hole is sealed with water-resistant glue. A removable endplate  15  is used to close tightly the opening of the enclosure  3  with two screws  16  that go into four matching inserts  17 . Preferably, a water-resistant sealing layer (not shown in  FIG. 2 ), made from such material as rubber, exists between the endplate  15  and the opening edge of the enclosure  3  to prevent rainwater and melting snow from entering into the enclosure.  
         [0025]     A preferred form of the display frame is shown in  FIG. 3 , where  FIG. 3   a  is a front view of the display frame  4  with address numbers  22  on both faces (only the front face number is shown in  FIG. 3   a ). Two mounting screws  19  are provided to fasten the frame to the mailbox or its post.  FIG. 3   b  is a cross-section view of A-A section, as indicated in  FIG. 3   a . As shown in  FIG. 3   b , the display frame  4  is a hollow frame, with two semi-transparent plastic plates as its two flat diffuser plates  21 . Two LEDs  18  sit at two ends of the frame  4  and are connected to the PCB  11  inside the assembly enclosure  3  by electrical extension wire  8  (as shown in  FIG. 2 ). Three Self-adhesive numerals  22  (for the three-digit address sign [321]) adhere onto the outer surface  23  of each flat diffuser plate  21 . A removable endplate  24  is provided to seal one open end of the display frame  4 .  
         [0026]     Preferably, optical fiber panels  26 , are used in the hollow space of the display frame  4 , between two diffuser plates  21 , as shown in  FIG. 4 . Light-emitting diodes  18 , as light sources, are used at end of the fiber panels  26 . The LEDs are connected to the PCB  14  inside the assembly enclosure  3  by extension wire  8  (as shown in  FIG. 2 ). The said optical fiber panels provide a uniform bright lighting background for the address numerals  22  on the diffuser plates  21 . The endplate  24  closes the frame opening tightly with two mounting screws  25 .  
         [0027]     Alternatively, the address display frame  4  takes a vertical position with address numerals  22  being aligned vertically, as showed in  FIG. 5 . The vertical address frame  4  is then installed on the mailbox post  2  via mounting screws  19 , as shown in  FIG. 5 .  
         [0028]     As shown in  FIG. 1 , an adjustable bracket set  6  is preferred to be used to install the assembly enclosure  3  on the mailbox post  2 . Via the bracket set  6 , the assembly enclosure  3  is adjusted to a tilted position that allows the solar cell  7  to face the Sun&#39;s position around the noontime when the solar radiation is the strangest.  FIG. 6  shows a desired design of the said bracket set, which consists of a horizontal arm  27  and a vertical arm  28 . One side  29  of the horizontal arm  27  is in contact with the mailbox post and fastened by an adjusting/fastening screw  30 . The horizontal arm  27  rotates with the adjusting/fastening screw  30 . The vertical arm  28  rotates with another adjusting/fastening screw  31 , as shown in  FIG. 6 . With these two rotating adjustments, the facing orientation of the solar cell  7  can be adjusted toward a desired direction. After adjustment is done, the horizontal arm  27  and the vertical arm  28  can be fastened tightly by the said screws  30  and  31 , respectively.  
         [0029]     An integrated one-unit device is mounted on the top of an existing mailbox  1  with mounting screws  19 , as shown in  FIG. 7 . The device is a sole display frame  4  with all the afore-mentioned illuminating features, but has extra hollow space to house the rechargeable batteries and the electric circuit (not shown in  FIG. 7 ). It contains the same address number sign  5 . A long rectangular solar cell  32  and the photo sensor  9  are at the top of the display frame  4 . The open end of the frame  4  is closed tightly with the endplate  24   
         [0030]     It is understood that alternative forms and arrangements of this invention, other than those described herein, exist. Such alternative forms and arrangements may be made without departing from the scope and spirit of this invention.