LIGHT SOURCE APPARATUS AND DRIVING APPARATUS THEREOF

• US 20090015172A1
• Filed: 06/05/2008
• Published: 01/15/2009
• Est. Priority Date: 07/11/2007
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute, UPEC Electronics Corporation
• Inventors: Huang, Jui-Feng, Chung, Lung-Pin
• Granted Patent: US 7,888,888 B2
• Time in Patent Office: Days
• US Class Current: 315/246
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A light source driving apparatus to drive at least one light source module includes a switch unit for coupling in series with an AC power source and the light source module; a clock synchronization unit for coupling to the AC power source and to provide a clock synchronization signal in accordance with an AC voltage of the AC power source; a control unit coupled to receive the clock synchronization signal and to provide to the switch unit an adjusting signal according to a timing of the clock synchronization signal; and a feedback unit coupled to the control unit and to detect a load state of the light source module, the feedback unit configured to provide to the control unit a feedback signal having a value representative of the detected load state of the light source module. The control unit is configured to modulate a pulse width of the adjusting signal according to the feedback signal and a preset brightness value of the light source module, the switch unit responsive to the adjusting signal to open and close to apply the AC voltage to the light source module in accordance with the modulated pulse width.

Claims

1. A light source driving apparatus to drive at least one light source module, the light source driving apparatus comprising:

a switch unit for coupling in series with an AC power source and the light source module;

a clock synchronization unit for coupling to the AC power source and to provide a clock synchronization signal in accordance with an AC voltage of the AC power source;

a control unit coupled to receive the clock synchronization signal and to provide to the switch unit an adjusting signal according to a timing of the clock synchronization signal; and

a feedback unit coupled to the control unit and to detect a load state of the light source module, the feedback unit configured to provide to the control unit a feedback signal having a value representative of the detected load state of the light source module;

wherein the control unit is configured to modulate a pulse width of the adjusting signal according to the feedback signal and a preset brightness value of the light source module, the switch unit responsive to the adjusting signal to open and close to apply the AC voltage to the light source module in accordance with the modulated pulse width.

2. The light source driving apparatus of claim 1 wherein the light source module comprises a light emitting diode string.

3. The light source driving apparatus of claim 1 further including a rectifier coupled to receive and rectify the AC voltage as a first voltage and provide a second AC voltage, the switch unit coupled to the rectifier to receive the second AC voltage.

4. The light source driving apparatus of claim 3 wherein the rectifier is a bridge rectifier.

5. The light source driving apparatus of claim 3 wherein the rectifier includes first and second output terminals on which to provide the second AC voltage, the switch unit including a switching element for coupling in series between one of the first and second output terminals and the light source module.

6. The light source driving apparatus of claim 5 wherein one of the first and second output terminals is grounded.

7. The light source driving apparatus of claim 1 wherein the clock synchronization unit comprises:

a voltage divider for coupling to the AC voltage to provide a divided voltage;

a variable resistor for coupling between first and second voltages to provide a variable output voltage; and

a comparator coupled to receive the divided voltage and the variable output voltage and to provide the clock synchronization signal based on a comparison of the divided voltage and the variable output voltage.

8. The light source driving apparatus of claim 7 wherein the voltage divider includes two resistors for coupling in series between the AC voltage and ground.

9. The light source driving apparatus of claim 7 wherein the first voltage is a reference voltage and the second voltage is ground.

10. The light source driving apparatus of claim 1 wherein the control unit comprises:

a microcontroller, coupled to the clock synchronization unit, the switch unit, and the feedback unit, the microcontroller being configured to convert the preset brightness value into a value representative of a driving current for comparison with the feedback signal, the microcontroller providing the adjusting signal according to a result of the comparison.

11. The light source driving apparatus of claim 1 wherein the switch unit comprises:

a first transistor having first and second terminals for coupling in series between the AC power source and the light source module and a third terminal, the first transistor being responsive to a signal applied to the third terminal thereof to control the conductivity between its first and second terminals; and

a second transistor having a first terminal coupled to the third terminal of the first transistor, a second terminal for coupling to a predetermined voltage, and a third terminal, the second transistor being responsive to a signal applied to the third terminal thereof to control the conductivity between its first and second terminals, the third terminal of the second transistor coupled to receive the adjusting signal from the control unit.

12. The light source driving apparatus of claim 11 wherein the switch unit further comprises:

a first resistor coupled across the first and third terminals of the first transistor;

a second resistor coupled in series between the third terminal of the first transistor and the first terminal of the second transistor;

a third resistor coupled in series between the third terminal of the second transistor and the control unit; and

a fourth resistor coupled between the third terminal of the second transistor and the predetermined voltage.

13. The light source driving apparatus of claim 12 wherein the predetermined voltage is ground.

14. The light source driving apparatus of claim 11 wherein the first transistor is an MOS transistor.

15. The light source driving apparatus of claim 11 wherein the second transistor is a bipolar junction transistor.

16. The light source driving apparatus of claim 1 wherein the feedback unit comprises an integrating circuit.

17. The light source driving apparatus of claim 16 further including a current sensing resistor for coupling in series with the light source module;

wherein the integrating circuit comprises;

a first resistor coupled at one end between the current sensing resistor and at the other end to the control unit; and

a second resistor, a capacitor, and a diode coupled in parallel together between the second end of the first resistor and a predetermined voltage.

18. The light source driving apparatus of claim 17 wherein the predetermined voltage is ground.

19. A light source driving apparatus to drive a plurality of light source modules, the light source driving apparatus comprising:

a first switch unit for coupling in series with an AC power source and a first one of the light source modules;

a second switch unit coupled in parallel with the first switch unit and in series with the AC power source and a second one of the light source modules;

a clock synchronization unit for coupling to the AC power source and to provide a clock synchronization signal in accordance with an AC voltage of the AC power source;

a control unit coupled to receive the clock synchronization signal and to provide to the first and second switch units first and second adjusting signals, respectively, according to a timing of the clock synchronization signal; and

first and second feedback units coupled to the control unit and to detect a load state of the first and second light source modules, respectively, the first and second feedback units configured to provide to the control unit first and second feedback signals, respectively, having values representative of the respective detected load states of the first and second light source modules;

wherein the control unit is configured to modulate a pulse width of each of the first and second adjusting signals according to the first and second feedback signals, respectively, and a preset brightness value of each of the first and second light source modules, the first and second switch units respectively responsive to the first and second adjusting signals to open and close to respectively apply the AC voltage to the first and second light source modules in accordance with the modulated pulse widths of the first and second adjusting signals.

20. A light source driving apparatus to drive first, second, and third light source modules, the light source driving apparatus comprising:

a first switch unit for coupling in series with an AC power source and the first light source module;

a second switch unit coupled in parallel with the first switch unit and in series with the AC power source and the second light source module;

a third switch unit coupled in parallel with the first switch unit and the second switch unit and in series with the AC power source and the third light source module;

a clock synchronization unit for coupling to the AC power source and to provide a clock synchronization signal in accordance with an AC voltage of the AC power source;

a control unit coupled to receive the clock synchronization signal and to provide to the first, second, and third switch units first, second, and third adjusting signals, respectively, according to a timing of the clock synchronization signal; and

first, second, and third feedback units coupled to the control unit and to detect a load state of the first, second, and third light source modules, respectively, the first, second, and third feedback units configured to provide to the control unit first, second, and third feedback signals, respectively, having values representative of the respective detected load states of the first, second, and third light source module;

wherein the control unit is configured to modulate a pulse width of each of the first, second, and third adjusting signals according to the first, second, and third feedback signals, respectively, and a preset brightness value of each of the first, second, and third light source modules, the first, second, and third switch units respectively responsive to the first, second, and third adjusting signals to open and close to respectively apply the AC voltage to the first, second, and third light source modules in accordance with the modulated pulse widths of the first, second, and third adjusting signals.

21. A light source driving apparatus, comprising:

a light source module;

a switch unit coupled in series with an AC power source and the light source module;

a clock synchronization unit for coupling to the AC power source and to provide a clock synchronization signal in accordance with an AC voltage of the AC power source;

a control unit coupled to receive the clock synchronization signal and to provide to the switch unit an adjusting signal according to a timing of the clock synchronization signal; and

a feedback unit coupled to the control unit and to detect a load state of the light source module, the feedback unit configured to provide to the control unit a feedback signal having a value representative of the detected load state of the light source module;

wherein the control unit is configured to modulate a pulse width of the adjusting signal according to the feedback signal and a preset brightness value of the light source module, the switch unit responsive to the adjusting signal to open and close to apply the AC voltage to the light source module in accordance with the modulated pulse width.

22. The light source driving apparatus of claim 21 wherein the light source module comprises a light emitting diode string.

23. The light source driving apparatus of claim 21 further including a rectifier coupled to receive and rectify the AC voltage as a first voltage and provide a second AC voltage, the switch unit coupled to the rectifier to receive the second AC voltage.

24. The light source driving apparatus of claim 23 wherein the rectifier is a bridge rectifier.

25. The light source driving apparatus of claim 23 wherein the rectifier includes first and second output terminals on which to provide the second AC voltage, the switch unit including a switching element for coupling in series between one of the first and second output terminals and the light source module.

26. The light source driving apparatus of claim 25 wherein one of the first and second output terminals is grounded.

27. The light source driving apparatus of claim 21 wherein the clock synchronization unit comprises:

a voltage divider for coupling to the AC voltage to provide a divided voltage;

a variable resistor for coupling between first and second voltages to provide a variable output voltage; and

a comparator coupled to receive the divided voltage and the variable output voltage and to provide the clock synchronization signal based on a comparison of the divided voltage and the variable output voltage.

28. The light source driving apparatus of claim 27 wherein the voltage divider includes two resistors for coupling in series between the AC voltage and ground.

29. The light source driving apparatus of claim 27 wherein the first voltage is a reference voltage and the second voltage is ground.

30. The light source driving apparatus of claim 21 wherein the control unit comprises:

a microcontroller, coupled to the clock synchronization unit, the switch unit, and the feedback unit, the microcontroller being configured to convert the preset brightness value into a value representative of a driving current for comparison with the feedback signal, the microcontroller providing the adjusting signal according to a result of the comparison.

31. The light source driving apparatus of claim 21 wherein the switch unit comprises:

a first transistor having first and second terminals for coupling in series between the AC power source and the light source module and a third terminal, the first transistor being responsive to a signal applied to the third terminal thereof to control the conductivity between its first and second terminals; and

a second transistor having a first terminal coupled to the third terminal of the first transistor, a second terminal for coupling to a predetermined voltage, and a third terminal, the second transistor being responsive to a signal applied to the third terminal thereof to control the conductivity between its first and second terminals, the third terminal of the second transistor coupled to receive the adjusting signal from the control unit.

32. The light source driving apparatus of claim 31 wherein the switch unit further comprises:

a first resistor coupled across the first and third terminals of the first transistor;

a second resistor coupled in series between the third terminal of the first transistor and the first terminal of the second transistor;

a third resistor coupled in series between the third terminal of the second transistor and the control unit; and

a fourth resistor coupled between the third terminal of the second transistor and the predetermined voltage.

33. The light source driving apparatus of claim 22 wherein the predetermined voltage is ground.

34. The light source driving apparatus of claim 31 wherein the first transistor is an MOS transistor.

35. The light source driving apparatus of claim 31 wherein the second transistor is a bipolar junction transistor.

36. The light source driving apparatus of claim 21 wherein the feedback unit comprises an integrating circuit.

37. The light source driving apparatus of claim 36 further including a current sensing resistor coupled in series with the light source module;

wherein the integrating circuit comprises;

a first resistor coupled at one end between the current sensing resistor and at the other end to the control unit; and

a second resistor, a capacitor, and a diode coupled in parallel together between the second end of the first resistor and a predetermined voltage.

38. The light source driving apparatus of claim 37 wherein the predetermined voltage is ground.

39. A light source driving apparatus to drive at least one light source module, the light source apparatus comprising:

a switch unit for coupling in series with an AC power source and the light source module;

a clock synchronization unit for coupling to the AC power source and to provide a clock synchronization signal in accordance with an AC voltage of the AC power source;

a control unit coupled to receive the clock synchronization signal and to provide to the switch unit an adjusting signal according to a timing of the clock synchronization signal;

a feedback unit coupled to the control unit and to detect a load state of the light source module, the feedback unit configured to provide to the control unit a feedback signal having a value representative of the detected load state of the light source module; and

a sensor unit to detect a brightness of light emitted from the light source module when driven and to provide to the control unit a signal representative of the detected brightness;

wherein the control unit is configured to modulate a pulse width of the adjusting signal according to the feedback signal, a preset brightness value of the light source module, and the detected brightness, the switch unit responsive to the adjusting signal to open and close to apply the AC voltage to the light source module in accordance with the modulated pulse width.

40. The light source driving apparatus of claim 39 wherein the control unit is further configured to modulate the pulse width of the adjusting signal to cause the detected brightness to approach the preset brightness.

41. The light source driving apparatus of claim 39 wherein the light source module emits light of only one color.

42. A light source driving apparatus to drive a plurality of light source modules, the light source apparatus comprising:

a first switch unit for coupling in series with an AC power source and a first one of the light source modules;

a second switch unit coupled in parallel with the first switch unit and in series with the AC power source and a second one of the light source modules;

a clock synchronization unit for coupling to the AC power source and to provide a clock synchronization signal in accordance with an AC voltage of the AC power source;

a control unit coupled to receive the clock synchronization signal and to provide to the first and second switch units non-overlapping first and second adjusting signals, respectively, according to a timing of the clock synchronization signal; and

first and second feedback units coupled to the control unit and to detect a load state of the first and second light source modules, respectively, the first and second feedback units configured to provide to the control unit first and second feedback signals, respectively, having values representative of the respective detected load states of the first and second light source modules, each of the first and second light source modules being configured to only emit light of first and second colors, respectively;

a color sensor unit to detect a brightness of the first color light and the second color light when emitted by the first and second light sources, respectively, and to provide to the control unit signals respectively representative of the detected brightness of the emitted first and second color lights;

wherein the control unit is configured to modulate a pulse width of each of the first and second adjusting signals according to the first and second feedback signals, respectively, a preset brightness value of each of the first and second light source modules, and the detected brightness of the emitted first and second color light, the first and second switch units respectively responsive to the first and second adjusting signals to open and close to respectively apply the AC voltage to the first and second light source modules in accordance with the modulated pulse widths of the non-overlapping first and second adjusting signals, so that the first and second light source modules are driven to light at non-overlapping times.

43. The light source driving apparatus of claim 42 wherein the control unit is further configured to modulate the pulse width of the adjusting signal to cause the detected brightnesses of the emitted first and second color light to approach the preset brightnesses for the first and second color light.