Abstract:
A light emitting diode (LED) driving device with control based on LED setting resistance is disclosed. The LED driving device is applied to an LED lighting fixture having a setting resistor and is configured to modulate output voltage and output current according to the setting resistor to fit the power requirement of the LED lighting fixture. The LED driving device includes a power conversion module and a driving module. The driving module includes a microprocessor and controlling unit. The microprocessor is electrically connected to the LED lighting fixture for sensing the setting resistor and generates a controlling signal in accordance with the sensed setting resistor to the controlling unit. The controlling unit is electrically connected to the microprocessor and the power conversion module and configured to drive the power conversion module to modulate output current and output voltage according to the controlling signal.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Field of the Invention 
         [0002]    The present invention relates to driving device, and in particular to a light emitting diode driving device. 
         [0003]    Description of Related Art 
         [0004]    Light emitting diodes (LEDs) have high luminous efficiency, long service time, widely operation temperature and environmental mercury-free, making them beyond the incandescent and fluorescent light bulbs, and led lighting field into a new solid-state lighting era. 
         [0005]    General lighting fixtures, such as incandescent lamps, fluorescent bulbs or lamps are usually driven by alternative current (AC) electric power, however, the LEDs are driven be direct current (DC) electric power. Thus, an essential condition for replacing incandescent lamps, fluorescent bulbs or lamps with LED lighting fixture is that the LED lighting fixture can directly connected to AC electric power. 
         [0006]    LEDs are semiconductor devices with low turn on voltage, and can emit light when an electrical current is passed through it in a specific direction. Moreover, LEDs are also current dependent devices with their light output intensity being directly proportional to the forward current flowing therethrough. Since the LEDs cannot have totally same parameters (such as internal resistance) even in the same manufacturing process, the same type of lighting fixtures with the LEDs cannot provide light with the same luminous intensity. 
       SUMMARY OF THE INVENTION 
       [0007]    An object of the present invention is to provide a light emitting diode (LED) driving device, which is used for driving an LED lighting fixture, the LED driving device can applied to different LED lighting fixtures, and makes the LED lighting fixtures have the same luminosity. 
         [0008]    According to one aspect of the present disclosure, a LED driving device applied to an LED lighting fixture having a setting resistance includes a power conversion module and a driving module. The driving module includes a microprocessor and a controlling unit. The microprocessor is electrically connected to the LED lighting fixture, and the controlling unit is electrically connected to the microprocessor and the power conversion module. 
         [0009]    The microprocessor senses the setting resistance of the LED lighting fixture and sends a controlling signal according to the setting resistance to the controlling unit, and the controlling unit receives the controlling signal and drives the power conversion module to modulate output current and output voltage according to the controlling signal. 
         [0010]    The LED driving device modulates output voltage and output current according to the setting resistance of the LED light fixture, so that the LED light fixture not only can effective be drived but also achieve the effect of energy conservation. 
     
    
     
       BRIEF DESCRIPTION OF DRAWING 
         [0011]    The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, may be best understood by reference to the following detailed description of the invention, which describes an exemplary embodiment of the invention, taken in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a circuit diagram of a light emitting diode (LED) driving circuit according to a first embodiment of the present disclosure; 
           [0013]      FIG. 2  is a circuit diagram of a driving component according to the first embodiment of the present disclosure; and 
           [0014]      FIG. 3  is a circuit diagram of an LED driving device according to a second embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    A preferred embodiment of the present invention will be described with reference to the drawings. 
         [0016]    Reference is made to  FIG. 1 , which is a circuit diagram of a light emitting diode (LED) driving device according to a first embodiment of the present invention. The LED driving device  1  is applied to an LED lighting fixture  3  with a maximum output power of 60 watts. In particular, the LED driving device  1  is applied to the LED lighting fixture  3  with the maximum output power of 50 watts. The LED light fixture  3  can be light tube, road lamp, light bulb or other lighting apparatus having LED. 
         [0017]    The LED driving device  1  includes a power conversion module  10 , a pulse width modulating unit  12 , and a driving module  14 . The LED lighting fixture  3  is electrically connected to the driving module  14  and receives an electric power outputted by the LED driving device  1 . 
         [0018]    The power conversion module  10  includes a rectifying unit  100  and a conversion unit  102 . The rectifying unit  100  is electrically connected to an alternative current (AC) electric power (not otherwise herein labeled) and used for converting the AC electric power into a direct current (DC) electric power, the DC electric power is then transmitted to the conversion unit  102 . The rectifying unit  100  can be a bridge rectifier, and the conversion unit  102  can be an isolating transformer having a primary winding  104  and a secondary winding  106 . The rectifying unit  100  is electrically connected to the primary winding  104  of the conversion unit  102 , and the driving unit  14  is electrically connected to the secondary winding  106  of the conversion unit  102 . 
         [0019]    The driving module  14  includes a controlling unit  140 , a microprocessor  142 , and a plurality of resistance sensing terminals R+ and R−. The controlling unit  140  is electrically connected to the secondary winding  106  of the power conversion unit  10 , and the microprocessor  142  is electrically connected to the pulse width modulating unit  12  and the controlling unit  140 . One side of each of the resistance sensing terminal R+, R− is electrically connected to the microprocessor  142 , and the other side of each of the resistance terminal R+, R− is electrically connected to the LED lighting fixture  3  for sensing a setting resistance of the LED lighting fixture  3 . The sensed setting resistance is then transmitted to the microprocessor  142 . The LED driving device  1  further includes an optical isolator  16  arranged between the microprocessor  142 , the controller  140 , and the pulse width modulating unit  12 . The optical isolator  16  includes a lighting emitting side  160  and a light receiving side  162 , the light emitting side  160  is electrically connected to the microprocessor  142  and the controlling unit  140 , and the light receiving side  162  is electrically connected to the pulse width modulating unit  12 . 
         [0020]    The controlling unit  140  includes a driving component  1400 , a first resistor R 1 , a second resistor R 2 , a third resistor R 3 , a fourth resistor R 4 , a fifth resistor R 5 , a sixth resistor R 6 , a seventh resistor R 7 , an eighth resistor R 8 , and a ninth resistor R 9 . The driving unit  1400 , the first resistor R 1 , the second resistor R 2 , and a resistance unit  144  collectively form a constant-current controlling circuit, wherein the resistance unit  144  formed by the third resistor R 3  and the fourth resistor R 4  electrically connected in parallel. The driving unit  1400 , the fifth resistor R 5 , the sixth resistor R 6 , the seventh resistor R 7 , the eighth resistor R 8 , and the ninth resistor R 9  collectively form a constant-voltage controlling unit. 
         [0021]    Reference is made to  FIG. 2 , which is a circuit diagram of a driving component according to the first embodiment of the present disclosure. The driving component  1400  includes a first operational amplifier OP 1  and second operational amplifier OP 2 , not only the first operational amplifier OP 1  but also the second operation amplifier OP 2  includes an inverting input end, a non-inverting input end, and an output end. 
         [0022]    The inverting input end of the second operational amplifier OP 2  is electrically connected to the first resistor R 1 , and the non-inverting input end thereof is electrically connected to the second resistor R 2 , the third resistor R 3 , and the fourth resistor R 4  via a first internal resistor Ra. The output end of the second operational amplifier OP 2  is electrically connected to the pulse width modulating unit  12  via the optical isolator  16 . 
         [0023]    With refer again to  FIG. 1 , one end of the second resistor R 2  is electrically connected to the driving component  1400  and the resistance unit  144 , and the other end thereof is electrically connected to the microprocessor  142 . One end of the resistance unit  144  is electrically connected to the driving component  1400 , and the other end thereof is electrically connected to the secondary winding  106  of the power conversion module  10 . 
         [0024]    The inverting end of the first operational amplifier OP 1  is electrically connected to the fifth resistor R 5 , the sixth resistor R 6 , and the seventh resistor R 7 , the non-inverting end thereof is electrically connected to the non-inverting end of the second operational amplifier OP 2  via the second internal resistor Rb. The output end of the first operational amplifier OP 1  is electrically connected to the pulse width modulating unit  12  via the optical isolator  16 . The non-inverting end of the first operational amplifier OP 1  can also be electrically connected to a constant-voltage source VDD, such as a DC power source which can provide an electric power with 2.5 volts. 
         [0025]    One end of the sixth resistor R 6  is electrically connected to the driving component  1400 , and the other end thereof is electrically connected to ground. One end of the seventh resistor R 7  is electrically connected to the driving component  1400 , and the other end thereof is electrically connected to the secondary winding  106  of the conversion unit  102 . One end of the eighth resistor R 8  is electrically connected to the microprocessor  142 , and the other end thereof is electrically connected to the fifth resistor R 5 . One end of the ninth resistor R 9  is electrically connected to the fifth resistor R 5  and the eighth resistor R 8 , and the other end thereof is electrically connected to ground. 
         [0026]    The microprocessor  142  senses the setting resistance of the LED lighting fixture  3  via the resistance sensing terminals R+ and R−, and generates a controlling signal according to the Table 1 via the current output terminal RA 1 , and then sends the controlling signal to the controlling unit  140 , such that the output current and output voltage of the LED driving device  1  can be modulated by the pulse width modulating unit  12  which receives a driving signal generated by the controlling unit  140  according to the controlling signal. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Setting 
                 Output 
                 Output 
                 Maximum 
                 Maximum 
               
               
                 Resistance 
                 Current 
                 Voltage 
                 Output 
                 Output 
               
               
                 (KOhm) 
                 (A) 
                 (V) 
                 Voltage (V) 
                 Power (W) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0.832 
                 0.503 
                 20~50 
                 50 
                 25.2 
               
               
                 0.866 
                 0.518 
                 20~50 
                 50 
                 25.9 
               
               
                 1 
                 0.535 
                 20~50 
                 50 
                 26.8 
               
               
                 1.3 
                 0.57 
                 20~50 
                 50 
                 28.5 
               
               
                 1.5 
                 0.592 
                 20~50 
                 50 
                 29.6 
               
               
                 2 
                 0.642 
                 20~50 
                 50 
                 32.1 
               
               
                 2.55 
                 0.693 
                 20~50 
                 50 
                 34.7 
               
               
                 2.7 
                 0.703 
                 20~50 
                 50 
                 35.2 
               
               
                 3.3 
                 0.746 
                 20~50 
                 50 
                 37.3 
               
               
                 3.6 
                 0.77 
                 20~50 
                 50 
                 38.5 
               
               
                 3.9 
                 0.79 
                 20~50 
                 50 
                 39.5 
               
               
                 4.3 
                 0.813 
                 20~50 
                 50 
                 40.7 
               
               
                 4.7 
                 0.833 
                 20~50 
                 50 
                 41.7 
               
               
                 6.2 
                 0.905 
                 20~50 
                 50 
                 45.3 
               
               
                 7.5 
                 0.954 
                 20~50 
                 50 
                 47.4 
               
               
                 8.2 
                 0.972 
                 20~50 
                 50 
                 48.6 
               
               
                 9.1 
                 0.995 
                 20~50 
                 50 
                 49.8 
               
               
                 9.53 
                 1.01 
                 20~50 
                 50 
                 50.5 
               
               
                 10 
                 1.02 
                 20~50 
                 50 
                 51 
               
               
                 11 
                 1.045 
                 20~48 
                 48 
                 50.2 
               
               
                 13 
                 1.08 
                 20~45 
                 45 
                 48.6 
               
               
                 15 
                 1.113 
                 20~44 
                 44 
                 49 
               
               
                 20 
                 1.17 
                 20~42 
                 42 
                 49.1 
               
               
                 24 
                 1.203 
                 20~41 
                 41 
                 49.3 
               
               
                 30 
                 1.239 
                 20~40 
                 40 
                 49.6 
               
               
                 33 
                 1.25 
                 20~40 
                 40 
                 50 
               
               
                 43 
                 1.283 
                 20~39 
                 39 
                 50 
               
               
                 51 
                 1.3 
                 20~37 
                 37 
                 48.1 
               
               
                 82 
                 1.34 
                 20~36 
                 36 
                 48.2 
               
               
                 120 
                 1.36 
                 20~36 
                 36 
                 49 
               
               
                 620 
                 1.388 
                 20~36 
                 36 
                 50 
               
               
                 820 
                 1.39 
                 20~36 
                 36 
                 50 
               
               
                   
               
             
          
         
       
     
         [0027]    The LED driving device  1  of the present disclosure modulates output voltage and output current according to the setting resistance of the LED light fixture  3 , so that the LED driving device  1  can provide enough electric power to the LED light fixture  3 , and dissipation of electric energy can be effectively reduced to achieve the effect of energy conservation. 
         [0028]    Reference is made to  FIG. 3 , which is a circuit diagram of the LED driving device according to a second embodiment of the present disclosure. The LED driving device  1   a  is similar to the LED driving device  1  mentioned in the first embodiment, and the same reference numbers are used in the drawings and the description to refer to the same parts. It should be noted that controlling unit  14  of the LED driving device  1   a  further includes an integrated circuit  146  and a variable resistor  148 , and there is no second resistor R 2  in the LED driving device  1   a . The integrated circuit  146  is electrically connected to the microprocessor  142 , and the variable resistor  148  is electrically connected to the integrated circuit  146  and the resistance unit  144 . As can be shown in  FIG. 3 , the variable resistor  148  is electrically connected to the resistance unit  144  in series. In the practical application, however, the variable resistor  148  can be electrically connected to the resistance unit  144  in parallel. 
         [0029]    The microprocessor  132  senses the setting resistance of the LED lighting fixture  3  via the resistance sensing terminals R+ and R−, generates a controlling signal according to the Table 1 for changing the resistor value of the variable resistor  148 , such that an equivalent resistance of the resistance unit  144  and the variable resistor  148  is then changed. In this manner, the output current of the LED driving device  1   a  is changed by the driving signal generated by the controlling unit  140  according to the equivalent resistance. The function and relative description of other components of the LED driving device  1   a  are the same as that of first embodiment mentioned above and are not repeated here for brevity, and the LED driving device  1   a  can achieve the functions as the LED driving device  1  does. 
         [0030]    Although the present invention has been described with reference to the foregoing preferred embodiment, it will be understood that the invention is not limited to the details thereof. Various equivalent variations and modifications can still occur to those skilled in this art in view of the teachings of the present invention. Thus, all such variations and equivalent modifications are also embraced within the scope of the invention as defined in the appended claims.