LED array and LED module with chains of LEDs connected in parallel

• US 6,803,732 B2
• Filed: 12/20/2002
• Issued: 10/12/2004
• Est. Priority Date: 12/20/2001
• Status: Expired due to Fees

• Current Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Blümel, Simon, Kraus, Robert
• Primary Examiner(s): TRAN, THUY V
• Application Number:
  US10/324,431
• Publication Number:
  US 20030116773A1
• Time in Patent Office: 662 Days
• Field of Search: 315/149-151, 315/158-159, 315/291, 315/293, 315/302, 315/307, 315/308, 362/800
• US Class Current: 315/307
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 31/12 structurally associated with, e.g. formed in or on a common substrate with, one or more electric light sources, e.g. electroluminescent light sources, and electrically or optically coupled thereto semiconductor devices with at least one potential barrier or surface barrier adapted for light emission H01L33/00; amplifiers using electroluminescent element and photocell H03F17/00; electroluminescent light sources per se H05B33/00
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/30 Driver circuits
• CPC Class Codes: H05B 45/58 involving end of life detection of LEDs
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An LED array has a plurality of LED chains, which each have at least one LED and are connected in parallel. The LED array has at least one output for feeding back radiation generated to a power supply unit. Preferably, at least one reference LED chain is connected in parallel with the LED chains and a photosensitive component is provided, the photosensitive component detecting the radiation emitted by the reference LED chain. The photosensitive component generates a measurement signal in a manner dependent on the radiation generated by the reference LED chain, which signal serves for providing feedback to the power supply unit.

Claims

1. An LED array, comprising:

a plurality of LED chains each having at least one LED and connected in parallel with each other; and

at least one output for feeding back radiation generated to a power supply unit;

at least one reference LED chain connected in parallel with said LED chains;

a photosensitive component for detecting radiation emitted by said reference LED chain, said photosensitive component generating a signal in dependence on a radiation emitted by said reference LED chain for assisting in generating a measurement signal available at said output;

a converter circuit directly connected to said photosensitive component and receiving the signal, said convener circuit generating the measurement signal in dependence on the signal; and

said LED chains having a common main radiating direction and said reference LED chain having a reference radiating direction, said common main radiating direction being different from said reference radiating direction.

2. The LED array according to claim 1, wherein said photosensitive component detects only the radiation emitted by said reference LED chain.

3. The LED array according to claim 1, further comprising an encapsulation with a radiation exit opening formed therein, only the radiation generated by said LED chains being emitted through said radiation exit opening.

4. The LED array according to claim 1, further comprising regulating configurations with a respective one of said regulating configurations connected in series with a respective one of said LED chains or with said reference LED chain, said regulating configurations serving for setting currents in said LED chains and in said reference LED chain in accordance with a predetermined current distribution.

5. The LED array according to claim 4, wherein said regulating configurations contain current amplification circuits for impressing a current into said LED chains and said reference LED chain, respectively, in accordance with the predetermined current distribution.

6. The LED array according to claim 5, wherein each of said current amplification circuit has a regulating input for regulating the current in an associated one of said LED chains and said reference LED chain, said regulating input of each of said current amplification circuits are connected to one another.

7. The LED array according to claim 1, wherein the LED array serves for generating a light signal in a traffic signal.

8. The LED array according to claim 7, wherein the traffic signal is for a traffic light or a rail signal.

9. An LED module, comprising:

a power supply unit; and

an LED array according to claim 1 with said at least one output connected to said power supply unit for feeding back radiation generated to said power supply unit.

10. The LED module according to claim 9, wherein:

said power supply unit has output terminals;

said LED array has supply terminals connected to said output terminals of said power supply unit and said LED array generates a measurement signal; and

said power supply unit has a control input for controlling an output-terminal operating voltage for said LED array, said control input receiving the measurement signal.

11. The LED module according to claim 10, wherein the output-terminal operating voltage is regulated using the measurement signal in such a way that the radiation generated by said LED chains is approximately constant.

12. The LED module according to claim 11, wherein a decrease in radiation efficiency in said LED chains, which decrease occurs with advancing aging, is compensated for by regulating the output-terminal operating voltage.

13. The LED module according to claim 9, wherein:

said power supply unit has output terminals;

said LED array has Supply terminals connected to said output terminals of said power supply unit and generates a measurement signal; and

said power supply unit has a control input for controlling an output-terminal operating current for said LED array, said control input receiving the measurement signal.

14. The LED module according to claim 13, wherein the output-terminal operating current is regulated using the measurement signal in such a way that the radiation generated by said LED chains is approximately constant.

15. The LED module according to claim 14, wherein a decrease in radiation efficiency in said LED chains, which decrease occurs with advancing aging, is compensated for by regulating the output-terminal operating current.

16. The LED module according to claim 9, wherein the LED module serves for generating a light signal for a traffic signal.

17. The LED module according to claim 16, wherein the traffic signal is part of a traffic light or a rail signal.

18. An LED array, comprising:

a plurality of LED chains each having at least one LED and connected in parallel with each other; and

at least one output for feeding back radiation generated to a power supply unit;

at least one reference LED chain connected in parallel with said LED chains;

a photosensitive component for detecting radiation emitted by said reference LED chain, said photosensitive component generating a signal in dependence on a radiation emitted by said reference LED chain for assisting in generating a measurement signal available at said output;

a converter circuit directly connected to said photosensitive component and receiving the signal, said converter circuit generating the measurement signal in dependence on the signal; and

a screen covering only said reference LED chain and said photosensitive component.

19. The LED array according to claim 18, wherein said screen has a side with a diffusely reflecting surface, said side facing said reference LED chain.

20. The LED array according to claim 18, wherein said photosensitive component detects only the radiation emitted by said reference LED chain.

21. The LED array according to claim 18, further comprising an encapsulation with a radiation exit opening formed therein, only the radiation generated by said LED chains being emitted through said radiation exit opening.

22. An LED module, comprising:

a power supply unit; and

an LED array according to claim 18 with said at least one output connected to said power supply unit for feeding back radiation generated to said power supply unit.

23. The LED module according to claim 22, wherein:

said power supply unit has output terminals;

said LED array has supply terminals connected to said output terminals of said power supply unit and said LED array generates a measurement signal; and

said power supply unit has a control input for controlling an output-terminal operating voltage for said LED array, said control input receiving the measurement signal.

24. The LED module according to claim 23, wherein the output-terminal operating voltage is regulated using the measurement signal in such a way that the radiation generated by said LED chains is approximately constant.

25. The LED module according to claim 24, wherein a decrease in radiation efficiency in said LED chains, which decrease occurs with advancing aging, is compensated for by regulating the output-terminal operating voltage.

26. The LED module according to claim 22, wherein:

said power supply unit has output terminals;

said LED array has supply terminals connected to said output terminals of said power supply unit and generates a measurement signal; and

said power supply unit has a control input for controlling an output-terminal operating current for said LED array, said control input receiving the measurement signal.

27. The LED module according to claim 26, wherein the output-terminal operating current is regulated using the measurement signal in such a way that the radiation generated by said LED chains is approximately constant.

28. The LED module according to claim 27, wherein a decrease in radiation efficiency in said LED chains, which decrease occurs with advancing aging, is compensated for by regulating the output-terminal operating current.

29. The LED module according to claim 22, wherein the LED module serves for generating a light signal for a traffic signal.

30. The LED module according to claim 29, wherein the traffic signal is part of a traffic light or a rail signal.

31. An LED array, comprising:

a plurality of LED chains each having at least one LED and connected in parallel with each other; and

at least one Output for feeding back radiation generated to a power supply unit;

at least one reference LED chain connected in parallel with said LED chains;

a photosensitive component for detecting radiation emitted by said reference LED chain, said photosensitive component generating a signal in dependence on a radiation emitted by said reference LED chain for assisting in generating a measurement signal available at said output;

a converter circuit directly connected to said photosensitive component and receiving the signal, said converter circuit generating the measurement signal in dependence on the signal;

wherein said converter circuit has an output coupler with an input and an output, said converter circuit generating a voltage in a manner dependent on the radiation detected by said photosensitive component with which said input of said output coupler is driven, and said output of said output coupler is connected to said output for feeding back radiation generated to the power supply unit.

32. The LED array according to claim 31, wherein:

said photosensitive component is a photodiode having an anode side and a cathode side;

said converter circuit has a resistor connected in series with said photodiode;

said converter circuit further has a transistor with a base, an emitter and a collector, a zener diode connected to said emitter, and a collector resistor connected to said collector, said base connected to one of said anode side and said cathode side of said photodiode;

said input of said output coupler connected to said collector and said emitter of said transistor.

33. The LED array according to claim 31, wherein said output coupler is an optocoupler.

34. An LED module, comprising:

a power supply unit; and

an LED array according to claim 31 with said at least one output connected to said power supply unit for feeding back radiation generated to said power supply unit.

35. The LED module according to claim 34, wherein:

said power supply unit has output terminals;

said LED array has supply terminals connected to said output terminals of said power supply unit and said LED array generates a measurement signal; and

said power supply unit has a control input for controlling an output-terminal operating voltage for said LED array, said control input receiving the measurement signal.

36. The LED module according to claim 35, wherein the output-terminal operating voltage is regulated using the measurement signal in such a way that the radiation generated by said LED chains is approximately constant.

37. The LED module according to claim 36, wherein a decrease in radiation efficiency in said LED chains, which decrease occurs with advancing aging, is compensated for by regulating the output-terminal operating voltage.

38. The LED module according to claim 34, wherein:

said power supply unit has output terminals;

said LED array has supply terminals connected to said output terminals of said power supply unit and generates a measurement signal; and

said power supply unit has a control input for controlling an output-terminal operating current for said LED array, said control input receiving the measurement signal.

39. The LED module according to claim 38, wherein the output-terminal operating current is regulated using the measurement signal in such a way that the radiation generated by said LED chains is approximately constant.

40. The LED module according to claim 39, wherein a decrease in radiation efficiency in said LED chains, which decrease occurs with advancing aging, is compensated for by regulating the output-terminal operating current.

41. The LED module according to claim 34, wherein the LED module serves for generating a light signal for a traffic signal.

42. The LED module according to claim 41, wherein the traffic signal is part of a traffic light or a rail signal.