Abstract:
A solar-powered LED street light that can immediately report its power data. The disclosed LED street light has a solar cell, a switch power supply unit, and a power cable data communicating unit. The mains power cable of the LED street light connects to the switch power supply unit for providing it with DC power. The solar cell has a solar board, a battery and a charge controller. The charge controller can also provide the LED street light with DC power. The charge controller has a power data digital output interface for connecting with the power cable data communicating unit, outputting the power data of the solar cell to the power cable data communicating unit. Through the mains power cable, the status of solar cell of each LED lamp is monitored.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a solar-powered LED street light and, in particular, to a solar-powered LED street light that immediately reports its power data. 
     2. Description of Related Art 
     As natural resources and energy will be used up soon, it becomes important to save fossil energy and develop new everlasting energy. Therefore, countries all over the world are making efforts in this direction for public constructions. Taking the street light as one example, there are more LED street lights because the LED lamp has the advantage of low power consumption. Electrical power can be greatly saved if we widely adopt the LED street lights. 
     Since the LED street light uses DC power and is installed outdoors, most of them are equipped with solar cells. This can save the electrical power usage. Although including solar cells is good, it is quite expensive to maintain them. Generally speaking, the solar-powered LED street light also requires mains power in addition to the solar cells so that the power supply can be alternated. For maintenance personnel, the solar cells are more likely to be damaged than home-used ones because they are exposed outdoors. In order to check whether a solar cell is damaged, the maintenance technician usually has to use a galvanometer or some detector to measure it. Alternatively, the maintenance technician can determine whether it is damaged by downloading the solar cell power data. Apparently, such a maintenance process is too slow. During the time after the solar cell is damaged and before it is repaired, the LED street light has to rely on the mains power. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, an objective of the invention is to provide a solar-powered LED street light that immediately reports its power data to a remote end. This helps shortening the maintenance time. 
     To achieve the above-mentioned objective, the disclosed solar-powered LED street light comprises: 
     an LED lamp; 
     a solar cell, which include a solar board, a charge controller and a battery; wherein the charge controller is electrically connected between the solar board and the battery and is connected to the LED lamp so as to convert and output the electrical power in the battery to the LED lamp, the charge controller having a power data digital output interface; 
     a switch power unit, which is connected to an AC power source and whose output terminal is connected to the LED lamp, for converting the AC power into DC power and outputting it to the LED lamp; 
     a power cable data communicating unit, which is coupled to the AC power and electrically connected to the power data digital output interface of the charge controller to extract the power data of the solar cell, the power data being modulation processed and coupled into the AC power of the power cable so that they are transmitted out. 
     The charge controller of the solar cell in the solar-powered LED street light is further connected to the power cable data communicating unit, through which the power data thereof are loaded into the power cable and transmitted outward. A remote power cable communicating host extracts the power data reported from each solar-powered LED street light. Therefore, the solar cell of each LED street light can be centrally controlled and immediately determined to be working or not. 
     Another objective of the invention is to provide a solar-powered LED street light with real-time road images. The above-mentioned LED street light is further provided with a video camera that has a video data output terminal connected with the power cable data communicating unit. The power cable data communicating unit loads the road images captured by the video camera on the LED street light and sends them outwards. Thereby, the remote power cable communicating host can extract the road images captured by the video camera on each LED street light. This achieves the objective of monitoring the road conditions in real time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a solar-powered LED street light in accordance with the first embodiment; 
         FIG. 2  is a plan view of a solar-powered LED street light in accordance with the second embodiment; 
         FIG. 3  is a circuit diagram for  FIG. 1 ; 
         FIG. 4  is a circuit diagram for  FIG. 2 ; 
         FIG. 5  is a circuit block diagram of a partial digital pulse width modulator in accordance with the present invention; and 
         FIG. 6  shows the connection structure of a power cable network and a remote power cable communicating host in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to  FIG. 1 , a solar-powered LED street light  10  comprises a lamppost  101 , an LED lamp  11 , a solar cell  12 , a mains power cable  102 , a switch power supply unit  20 , and a power cable data communicating unit  30 . With further reference to  FIG. 2 , the second embodiment of the solar-powered LED street light  10   a  further includes a video camera  13  being adjacent to the LED lamp  11 . 
     With reference to  FIGS. 3 and 6 , the solar cell  12  includes a solar board  121 , a battery  122  and a charge controller  123 . The solar board  121  is mounted on the lamp post  101  to absorb solar power and convert the solar power into DC power for output. The battery  122  is fixed on the lamp post  101 . The charge controller  123  is mounted on the lamp post  101  and electrically connects among the solar board  121 , the LED lamp  11  and the battery  122  to convert the DC power into the charging power for charging the battery  122 . The charge controller  123  may controls the battery  122  to output the power to the LED lamp  11 . The charge controller  123  may include a power data digital output interface  123   a , which may be a serial port such as the RS-232 or USB interface. 
     Since the charge controller  123  is electrically connected to the solar board  121 , the battery  122  and the LED lamp  11 , the charge controller  123  can check the status of the battery  122 . If the stored power in the battery  122  is low, the DC power output from the solar board  121  is adjusted to charge the battery  122 . When the LED lamp  11  should be turned on due to dim environmental light, the battery  122  output power to activate the LED lamp  11 . 
     The switch power supply unit  20  is connected to the mains power cable  102  to obtain an alternating power (AC). The output terminal of the switch power supply unit  20  connects to the LED lamp  11 . The switch power supply unit  20  converts the AC power into DC power, which is then output to the LED lamp  11  as its operating voltage. In this embodiment, the switch power supply unit  20  is a forward power circuit. However, the switch power supply unit  20  may be alternatively implemented as a flyback power circuit or a buck power circuit. To provide DC power to the power cable data communicating unit  30 , the switch power supply unit  20  further includes at least one DC to DC converter  26 . The DC to DC circuit can be a buck power circuit. The input terminal of the DC to DC converter connects to the DC output terminal of the switch power supply unit  20 , bucking the output voltage to a low DC voltage and supplying the low DC voltage to the power cable data communicating unit  30  as its operating voltage. 
     The power cable data communicating unit  30  is coupled to the mains power cable  102 , and is electrically connected with the power data digital output interface  123   a  of the charge controller  123 . The power cable data communicating unit  30  obtains the power data of the battery  122 , modulates and couples the data into the Mains power cable  102 . The power data of the solar cell  12  of the LED lamp  11  is transmitted out via the Mains power cable  102 . 
     The power cable digital communicating unit  30  comprises an analog front transceiving unit  31 , a digital processing unit  32 , a digital communicating interface  33 , and an electric isolator  34 . 
     The analog front transceiving unit  31  electrically connects to the DC to DC converter  26  and couples to the mains power cable  102 . 
     The digital processing unit  32  electrically connects to the DC to DC converter  26  and the analog front transceiving unit  31  to receive external data signals from the mains power cable  102  via the analog front transceiving unit  31 , or to process and modulate the data and couple them to the mains power cable  102  via the analog front transceiving unit  31  for sending them out. 
     The digital communicating interface  33  electrically connects to the power data digital interface  123   a  of the charge controller  123  to obtain the power data of the battery  122  and outputs the power data to the digital processing unit  32 . In this embodiment, the digital communicating interface  33  is a serial port such as the RS-232 or USB interface. 
     It is clear from the above description the charge controller  123  of the solar cell  12  of the solar-power LED street light  10  is connected to the power cable digital communicating unit  30 . The power data of the solar cell  12  is transmitted out via the mains power cable  102 . In this case, if a remote power cable communicating host  40  connects to a mains power network, it can readily extract the power data returned from all solar-powered LED street lights  10 . The all statuses of the solar-powered LED street lights  10  can be centrally managed and used to determine whether individual solar cells  122  are normal or damaged. 
     With reference to  FIGS. 4 and 6 , in this second embodiment, the solar-powered street light  10   a  further includes a video camera  13  that has a video data output terminal  131  and a power terminal Vcc. The video data output terminal  131  is electrically connected with the digital communicating interface  33  of the power cable digital-communicating unit  30 . The power terminal Vcc is connected to another DC to DC converter  27  of the switch power supply. The power digital communicating unit  30  processes and adjusts road images captured by the video camera  13  on the LED street light  10   a . The images are then loaded into the mains power cable  102  and transmitted outward. Therefore, the remote power cable communicating host  40  can receive the road images provided by the video cameras  13  on the LED street lights  10   a , readily monitoring the road conditions. 
     With further reference to  FIGS. 4 and 5 , the switch power supply circuit  20  may be a forward power circuit in this embodiment. The switch power supply circuit  20  includes a full wave rectifying filter  21 , a power factor correction controller  22 , a transformer T 1 , an active switch  23  connected to the primary side of the transformer T 1  in series, a digital pulse width (PWM) modulator  24 , and a photo coupler  25 , HCNR200. 
     The digital PWM modulator  24  has at least one digital interface  241  (e.g., I 2 C interface), a reference voltage modulating unit  242 , an operating amplifier  245 , a gain adjusting unit  243 , a driver  244 , a voltage feedback terminal V FB  and a driving output terminal OUT. 
     The photo coupler  25  directly connects between the voltage feedback terminal V FB  of the digital PWM modulator  24  and the voltage output terminal Vout of the forward flyback power circuit, thereby reflecting the DC voltage Vout thereof to the digital PWM modulator  24 . Since the digital PWM modulator  24  has a digital interface  241 , an electric isolator  34  can be used to obtain the command of adjusting the reference voltage output from the digital processing unit  32 , thereby adjusting an internal reference voltage. Afterwards, the feedback voltage and the modulated reference voltage are compared by the operating amplifier  245 . The gain of the comparison result is adjusted by the gain adjusting unit  243  and then output to the driver  244 . The driver  244  outputs a pulse width signal via the driving output terminal OUT based on the comparison result. This adjusts the conduction time of the driving active switch  23  and stabilizes the output voltage. 
     The power cable data communicating unit  30  and the switch power supply unit  20  do not have a common ground. The output terminal (I 2 C interface) of the digital processor  32  of the power cable data communicating unit  30  is connected to a digital interface of the digital PWM modulator  24  via the electric isolator  34  such as a transformer for changing the internal reference voltage of the digital PWM modulator  24  and accordingly changing the pulse width. Therefore, to increase the voltage and current on the secondary side of the transformer T 1  of the switch power supply unit, one simply increases the reference voltage on its internal reference voltage input terminal V REF . 
     Therefore, the digital processing unit  32  of the power cable data communicating unit  30  can receive the command of adjusting the brightness of the LED lamp  11  sent from the remote power cable communicating host  40 . The reference voltage of the digital PWM modulator  24  is adjusted via the electric isolator  34 , thereby increasing or reducing the brightness of the LED lamp  11 . In order for the video camera  13  on the LED street light  10   a  to obtain better road condition images, the remote power cable communicating host  40  can send out a control command to increase the illuminating light of the LED lamp  11 . 
     In summary, the solar-powered street light is more convenient for maintenance. With a video camera, the invention does not only achieve the effect of monitoring road conditions, it can also control the brightness of the LED lamp by reporting the power data of the solar cell via the power cable data communicating unit. The road images can thus be clearer. 
     Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.