Abstract:
A solar-charged power source for use in powering an electronic device, such as a game camera, comprises a housing, a photovoltaic cell provided on an upper surface of the housing, a battery and electronic circuitry, including a microcontroller, contained within the housing. A display is mounted on an outer surface of the housing and provides a user selectable indication of a microcontroller determined condition of the power source including the current charge state of the battery, a real time solar value indicating the electrical current production of the photovoltaic cell, a computed daily solar average and a weekly solar average of the current produced by the photovoltaic cell, based on the energy consumption requirements of the powered device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of prior U.S. Provisional application Ser. No. 61/021,184, filed Jan. 15, 2008, the disclosure of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to photovoltaic power cells. More particularly, the invention relates to a solar charged battery source for use in powering an electronic product, such as a game camera. More specifically, the battery source enables a user to select a location for optimal use of the solar panel based on real time and historical performance information. 
       SUMMARY OF THE INVENTION 
       [0003]    Briefly described, the present invention is a solar-charged power source for supplying electrical energy to an electronic device, such as a game camera. The invention comprises a photovoltaic cell for converting a light from a source, namely the sun, into electricity; a battery for storing at least a portion of the electricity converted by the photovoltaic cell; and an electrical circuit in communication with the battery, photovoltaic cell, and the electronic device; the electrical circuit comprising a microcontroller for managing electricity generated by the photovoltaic cell between the power source, battery and electronic device. The photovoltaic cell, the battery, and the electrical circuit are mounted in a housing having a bracket pivotally attached thereto for mounting the power source to a supporting structure. The pivotal attachment of the housing to the bracket permits adjustment of the housing so that the photovoltaic cell may be positioned to optimally receive light thereon. 
         [0004]    The microcontroller of the solar-charged power source is in electrical communication with an electronic display panel, such as an LCD, providing a user with an indication of a plurality of conditions to determine the operational status of the device. A first of the conditions is an indication of the intensity of the light received from the source by the photovoltaic cell, so that the photovoltaic cell may be positioned for optimum light reception and performance. A second of the plurality of conditions provides the user an indication of the charge condition of the battery associated with the device. A third of the plurality of conditions is an indication of the electricity converted by the photovoltaic cell during a predetermined period, typically the predetermined period is approximately twenty four hours. A fourth condition is an indication of the electricity converted by the photovoltaic cell during a plurality of predetermined periods, such as a seven day period, for a weekly average value. The displayed condition may be based on a user selection, or alternatively may it be automatically displayed based on instructions in the microprocessor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a top perspective view of the solar charged power source. 
           [0006]      FIG. 2  is a bottom perspective view of the solar-charged power source. 
           [0007]      FIG. 3  is a schematic view of the internal circuitry of the solar-charged power source. 
           [0008]      FIG. 4  is a flowchart illustrating process implemented by the microcontroller of the solar-charged power source. 
           [0009]      FIG. 5  is a side perspective view illustrating the display for the solar-charged power source. 
           [0010]      FIG. 6  is a side perspective view of the solar-charged power source. 
           [0011]      FIG. 7  is a back plan view of the solar-charged power source. 
           [0012]      FIG. 8  is a top end view of the solar-charged power source. 
           [0013]      FIG. 9  is a right side view of the solar-charged power source. 
           [0014]      FIG. 10  is a left side view of the solar-charged power source. 
           [0015]      FIG. 11  is a frontal view of the solar-charged power source. 
           [0016]      FIG. 12  is a bottom end view of the solar-charged power source. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Looking to  FIGS. 1 and 2 , a solar charged battery device  10  to provide electrical current for the operation of electronic equipment  12  is illustrated. In particular, the device  10  serves as an external power source providing electric current to various electronic products  12 , such as digital game cameras used in the field. The device  10  includes a solar panel  14  or cell that is mounted to a housing  16 . The housing  16  is pivotally connected to a base bracket  18 . Base bracket  18  may be attached in a variety of ways such as through the use of conventional connectors similar to U-bolts or bungee straps to a variety of secure bases such as a tree, limb, stump, pole, or similar solid member. In particular, the housing  16  may be pivotally connected to the bracket  18  using wing-nuts  20 , such that the relative position between the housing  16  and the bracket  18  may be adjusted and locked to achieve an optimal angle at the specific location where the device is mounted for the purposes described herein. 
         [0018]    The housing  16  contains an electrical circuit  22  that includes the solar panel  14 , an output junction  25 , and a battery  24 , such as a rechargeable 12-volt battery. The solar panel  14 , which may be any photovoltaic cell known in the art, is designed to convert light into electricity that is to be supplied to both the rechargeable battery  24  and an electronic product. Thus in this particular application, while the solar panel  14  is exposed to light during the day, it will provide electricity for operation of a game camera as well as recharging the battery  24 . 
         [0019]    The electric circuit  22  includes a microcontroller  26  or integrated circuit that is in electrical communication with both the solar panel  14  and the battery  24 . The microcontroller  26  is used to for various functions, with one function being to monitor the amount of current generated by the solar panel  14 , and provide corresponding information to the user via a display  28 , such as a liquid crystal display (LCD), so that the device  10  may be positioned in the most desirable location possible for receiving the required light. In particular, the solar cell  14  is connected to the microcontroller  26  across a resistive load R 5 , which provides values of the current to be interpolated by the microcontroller  26  as described herein. Further, the microcontroller  26  includes an integrated LCD driver to transmit the monitored information to the display  28 . Although a variety of microcontrollers  26  may be used as described herein, the model known to operate suitably is a Microchip PIC16F91X. 
         [0020]    The microcontroller  26  manages the solar energy effectively to power the camera, keep an internal battery  24  charged, and maintain a correct charge on an internal battery  24  so as not to overcharge it. That is, the microcontroller  26  will measure the charge on the battery  24  over a period of time to determine whether current generated by the solar cell  14  is to be directed to the power source  24  or to the product  12 . The microcontroller  26  has four functions to assist the user, including: 
         [0021]    1) The microcontroller  26  is connected to an electronic display  28  on the device  10  acting as a solar meter that measures the intensity of the solar energy being received, so the user can place the unit in the most effective place. 
         [0022]    2) The microcontroller  26  keeps up with the charge on the internal battery  24 . It will let the user know what the current state of charge is in the battery  24 . 
         [0023]    3) The microcontroller  26  tracks the daily amount (over a predetermined period, such as a 24 hour period) of power that the solar panel  14 s of the device  10  produce, and it displays this information to the user. 
         [0024]    4) The microcontroller  26  tracks the weekly average of power that the device  10  has produced over the last week per day. 
         [0025]    Thus, the microcontroller  26  provides four readouts to the user, namely, (1) real-time solar charge, (2) internal charge, (3) daily solar charge, and (4) weekly solar charge. These readouts are displayed to the user to assist the user in tracking the actual performance of the device  10  in the field based on the position of the device  10 . The first three readouts analyze the amount of current produced by the solar panel  14 , while the internal charge readout determines the energy stored via the battery  24  connected to the solar panel  14 . 
         [0026]    Looking at the circuit diagram of  FIG. 3 , the solar cell  14  is connected to the battery  24  and output port  25  used to provide electricity to the game camera  12 . Battery  24  is also connected being connected to output port  25  to provide electricity to the game camera  12  or other electronic product. A rubber plug strip covers the external power port  25 , which is easily detached to allow the user to plug in a cable  27  connecting the device  10  with the product  12 . The solar cell  14 , via D 3 , and battery  24 , via D 4 , are additionally connected to the On/Off switch  32 . Voltage regulator  33  is positioned between the microcontroller  26  and on off switch  32 . Voltage regulator  33  is preferably comparable to one of the XC6202 series, a highly precise, low power consumption, high voltage, positive voltage regulator consisting of a current limiter circuit, a driver transistor, a precision reference voltage and an error correction circuit. Output voltage supplied to the circuit by Voltage regulator  33  is +5 volts. 
         [0027]    The solar panel  14  is connected to the microcontroller/integrated circuit  26  via transistor Q 9  at pin RA 3 , with a load resistor R 5  of 49.9 ohms shunted between Q 9  and the microcontroller  26 . The microcontroller  26  therefore monitors the voltage drop over this resistor when Q 9  is conducting thereby indicating the current generated by solar cell  14 . RA 3  is the input to an analog to digital converter in microcontroller  26 . Using this information, the microcontroller  26  is programmed to calculate a Real-Time Solar (RTS) value, a Daily Solar Average (DSA) value, and a Weekly Solar Average (WSA) value of current produced by the solar cell  14 . The RTS value indicates the dynamic level of current produced when the solar panel  14  is connected across load R 5 . Using a 70 mA solar panel  14 , the minimum acceptable solar output current indication is 82 counts on the 10-bit analog/digital converter of the microcontroller  26  (which is 0.4V across a 49.9 ohm resistor or about 8+/−4 mA). During testing, it was found that a good high current (not the maximum) could be 614 counts on the 10-bit A/D converter of the microcontroller  26  (which is 3.0V across 49.9 ohms or about 60 mA+/−4 mA). While the actual solar-generated charge retained in the battery  24  is somewhat dependant on the type of battery  24  used in the design (e.g., internal resistance, current charge level) and typically a sealed lead acid (“SLA”) battery only retains about 70% of the energy delivered), this RTS value is a true representation of the current generation capabilities of the solar panel  14  in real-time to assist the user in selecting the optimal location for generating current. 
         [0028]    The calculation for the RTS value, scaled from 0 to 100, with 100 corresponding to a desired current production of 60 mA, is performed by the microcontroller  26  using the following formula: 
         [0000]      (A/D_Count−82)*100)/532. 
         [0000]    Based on the electronic equipment expected to be used with the present device  10 , solar currents that are 60 mA or over are indicated as an interpolated value of “100” (or an ideal spot to position the solar panel  14 ). Of course, the use of other equipment with this device  10  that requires more current for operation will adjust the RTS value. That is, if the equipment requires 350 mA, then the RTS value corresponding to 100 would be equivalent to 350 mA rather than 60 mA. 
         [0029]    The microcontroller  26  will also calculate the DSA value. Specifically, the value of A/D counts across the 49.9 ohm resistor R 5  are read every minute by the microcontroller  26  via the connection at pin RA 3 . This A/D value is converted to a milliamps value accurate to one decimal place and then added to a DSA accumulator also maintained in the microcontroller  26 . The conversion is based on empirical data collected from several solar panels  14 . As a side note, since this conversion is based on data collected from the solar panels  14 , the solar panels  14  must be in tolerance in order for the display to be accurate. After 1440 minutes (one 24-hour day), the Daily Solar Sum accumulator is divided by a value such as 1440 (corresponding to the number of minutes in the day), to determine the Daily Solar Average value available from the solar cell. Recall that some of this energy goes to the battery  24  and some of the energy goes to the product (e.g., the camera). 
         [0030]    To get the power savings needed on the device  10 , the microcontroller  26  selected for the device  10  has a low frequency, un-calibrated oscillator. This oscillator has a nominal frequency of 31 Khz; however, it can drift based on temperature and other factors. This means that timers based on the oscillator can vary based on temperature as well as from microcontroller  26  to microcontroller  26 . The DSA value is designed to be the average for the previous 24 hours. However, in worse case extremes, the average can drift without the use of additional components. In such cases, the timing can drift based on temperatures and other extraneous factors, and the “Day” could be the average from the previous 15-30 hours depending on drift of the oscillator. Since the length of the monitored “Day” can vary, the Daily Average is described as the running average for the predetermined “Day” and not necessarily defined as a standard 24-hour day. 
         [0031]    Finally, the microcontroller  26  also calculates the WSA value using a WSA accumulator, which is the average of seven daily averages. That is, the microcontroller  26  will add the DSA value for a predetermined number of days and divide the total by the number of days. The WSA value is dependant on the calculations of the Daily Solar Average, and will thus be adjusted as the DSA value is adjusted. Microcontroller  26  outputs the selected data to LCD  28  via jumper X. 
         [0032]    The process implemented by the microcontroller  26  of the device  10  is illustrated in the flow chart shown in  FIG. 4 . Initially, the device  10  is turned on by the user via the external On/Off button  32 , shown in  FIGS. 3 and 5 . The microcontroller  26  will configure the oscillator, timers, watchdog timer (used to wake-up the circuit  22  when in sleep mode), and LCD (step  100 ), and further initialize the process variables (step  102 ), such as clearing out all accumulator variables maintained by the microcontroller  26 , including the Daily Solar Average and Weekly Solar Average. The microcontroller  26  will then check the battery  24  and solar cell  14  operating information and update the totals (step  104 ). Initially, the device  10  will operate in Real-Time Solar Mode, and a one-minute timer maintained by the microcontroller  26  is initiated (step  106 ). The microcontroller  26  will read the Real Time Solar value and show the value on the display  28  for the user to read (step  108 ). If the mode button  34  is pressed or if the one-minute period has expired as checked by the microcontroller  26  (step  110 ), the microcontroller  26  will transition to the Internal Charge mode and update the display  28  with the Internal Charge of the battery  24  (step  112 ). If the mode button  34  is not pressed in step  110 , then step  108  is repeated. The microcontroller  26  will then go into sleep mode for a predetermined period, which in the embodiment described herein, is 168 milliseconds (step  114 ). 
         [0033]    At the end of the predetermined period, the microcontroller  26  will check to see if the mode button  34  is pressed (step  116 ). If so, then the mode will be incremented to Daily Solar Average mode (step  120 ). The microcontroller  26  will then check whether the mode is greater than the Weekly Solar average (step  122 ), and if not, the Daily Solar Average will be shown on the display  28  (step  124 ), and the process with then return to step  118 . If the mode is greater than the Weekly Solar Average at step  120 , then the process will return to step  106 . If the mode button  34  is not pressed by the user, the microcontroller  26  will check the one-minute timer to determine whether one-minute (or some other preset time limit) has expired. 
         [0034]    If the mode button  34  is not pressed at step  116 , then the microcontroller  26  will check the one-minute timer to see if one minute has expired (step  118 ). If so, the microcontroller  26  transitions to step  126  to read the battery  24  and solar values and update the Daily Solar Average. At step  128 , the microcontroller  26  checks to see if it has received one days worth of samples (i.e., 1,440 samples). If no, then the display  28  is updated (step  136 ) and the microcontroller  26  returns to step  114 . If the microcontroller  26  has collected one days worth of samples at step  128 , the microcontroller  26  will calculate the Solar Daily Average to be stored in a weekly array (step  130 ). The microcontroller  26  will then check to see if it has one week&#39;s samples (i.e., 10,080 samples) for the preceding week (step  132 ). If so, at step  134 , the weekly data is added together and divided by the predetermined period set for the week (conventionally seven days), and the display  28  is updated with the Weekly Solar Average (step  136 ). This process will continue until the user once again selects the On/Off button  32 , turning the device  10  off and further clearing and resetting the various variables maintained by the microcontroller  26  monitoring the real-time, daily and weekly charges of the device  10 . 
         [0035]    To recap, as the microcontroller  26  proceeds through each mode, the LCD will display the correct mode for the user as well as the value corresponding to the mode. The Real-Time Solar Mode variable indicates the amount of real-time solar energy that is being received by the device  10 . During setup, this screen can be used to position the solar panel  14  in the optimal position. Anywhere from 4 to 8+ hours of direct sun is required for optimal performance depending on camera model. Direct Sun is a Real Time Solar value of 50 or greater. The Real Time Solar screen will remain active for one minute before changing to the Internal Charge screen. To make active again after one minute, press the Mode button  34  until the Real Time Solar screen is displayed. 
         [0036]    In the Internal Charge Mode, the device  10  internally retains a solar charge so that it can continue to deliver energy to the camera through the night or on cloudy days. If this value drops below 50 on the display  28 , the device  10  may not be receiving enough solar energy and the user should consider selecting a sunnier location. Also, if the Internal Charge drops below 50 on the display  28 , it may be advantageous to do a complete re-charge on the unit. In this case, with power ON and the camera disconnected, set the device  10  in the direct sunlight for up to 8 hours or until the internal charge value is greater than 90. 
         [0037]    In the Daily Solar Average Mode, the device  10  tracks the amount of solar energy it receives each day. In the Weekly Solar Average Mode, the Weekly Solar Average is the average Solar Energy Level over the past week. In both the Daily and Weekly Solar Average modes, the variables are cleared and reset when the device  10  is turned off. 
         [0038]    Thus, this device  10  provides: the combination of a solar panel  14 , a rechargeable battery  24  and management microcontroller  26  and software; the “real-time solar” meter to aid the user in setting up the device  10  in the best location; the ability to show the internal battery  24  charge; the ability to track weekly and daily averages of electrical current produced by the device  10  to also aid the user in the optimal placement of the product; and the ability to correctly maintain a battery  24  charge in the device  10  and not overcharge the battery  24 . 
         [0039]    The device  10  manages the power produced by the solar panel  14  to directly power the camera or other product as well as charge the internal battery  24  of the device  10  to run the camera through the night or for a period of days of rain or bad weather when a solar panel  14  alone could not supply power to run the game camera. It provides the user with a readout for optimal solar panel  14  placement. It further provides the user the ability to see the state of charge of the battery  24  state of charge, and displays the actual electrical current produced by the panel  14  on a daily and weekly average. 
         [0040]    Referring again to  FIG. 4 , a jumper switch  36  may additionally be connected to the microcontroller  26  to conserve power used by the microcontroller  26  in biasing the LCD  28 . That is, the jumper switch  36  is typically connected to ground, and the resistors R 18 , R 19 , and R 20  are used to control the bias of the LCD  28 . When the switch  36  is turned to the on-position, power is taken off of these resistors R 18 , R 19 , and R 20 . While this is not necessary for proper operation of the device  10 , it may nonetheless assist the user in conserving the power generated by the solar cell  14 . 
         [0041]    Additional features may be incorporated into the device  10  to monitor the current production and use. For example, the microcontroller  26  may additionally calculate how much solar power is needed for the electronic product  12  based on the power being consumed daily on average. That is, the microcontroller  26  will monitor the outgoing current drawn by the electronic product  12  during a predetermined period (such as one day) and save that value as a reference value. This reference value is then compared with the Daily Solar Average (or comparable value) to determine if the solar cell  14  is producing the required current at its location. If so, the microcontroller  26  will transmit a message on the display  28  that the location is acceptable for proper use. If not, the microcontroller  26  will transmit a message on the display  28  that the device  10  needs to be moved to a new location. 
         [0042]    It should be understood that the portion of the circuit actually involved in charging battery  24  and powering device  12  has been illustrated in  FIG. 4 , but has not been verbally described in as much as the features claimed herein are not dependant upon those particulars. While a single embodiment of the present invention is shown in the drawings, it is not intended that the invention be so limited but rather that the invention be defined by the appended claims when given their full and broadest scope.