LIGHT EMITTING DIODE CIRCUIT AND ARRANGEMENT AND DEVICE

• US 20090284174A1
• Filed: 04/20/2007
• Published: 11/19/2009
• Est. Priority Date: 05/02/2006
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Sauerlander, Georg, Ackermann, Bernd
• Granted Patent: US 8,076,872 B2
• Time in Patent Office: Days
• US Class Current: 315/294
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

Disclosed are light emitting diode circuits employing first sub-circuits including first light emitting diodes and connected in parallel with second sub-circuits including second light emitting diodes and switches for, in conducting states, switching on the second light emitting diodes and switching off the first light emitting diodes and for, in non-conducting states, switching off the second light emitting diodes and switching on the first light emitting diodes. The first sub-circuits and the second sub-circuits have different signal characteristics such as different minimum threshold voltages to be realized by using different kinds of light emitting diodes, by using different total numbers of serial light emitting diodes, or by adding threshold voltage elements to the first sub-circuits.

Claims

1. A light emitting diode circuit comprising

a first sub-circuit comprising at least one first light emitting diode and connected to a pair of terminals, comprising a first terminal and a second terminal and

a second sub-circuit comprising at least one second light emitting diode and connected to the pair of terminals in parallel with the first sub-circuit, the second sub-circuit further comprising a first switch for, in a conducting state, switching on the second light emitting diode and switching off the first light emitting diode and for, in a non-conducting state, switching off the second light emitting diode and switching on the first light emitting diode.

2. The light emitting diode circuit of claim 1, wherein a first end of the first switch is connected to the first terminal and a second end of the first switch is connected to a part of the second sub-circuit comprising the second light emitting diode and extending between the second end of the first switch and the second terminal.

3. The light emitting diode circuit of claim 1, wherein the first and second light emitting diodes emit light of different colors.

4. The light emitting diode circuit of claim 1, further comprising:

a third sub-circuit comprising at least one third light emitting diode and connected to the pair of terminals in parallel with the first and second sub-circuits, third sub-circuit further comprising a second switch for, in a conducting state, switching on the third light emitting diode and switching off the first light emitting diode and for, in a non-conducting state, switching off the third light emitting diode and, switching on the first light emitting diode when the first switch is in the non-conducting state.

5. The light emitting diode circuit of claim 4, wherein a first end of the second switch is connected to the first terminal and a second end of the second switch is connected to a part of the third sub-circuit comprising the third light emitting diode, and extending between the second end of the second switch and the second terminal.

6. The light emitting diode circuit of claim 4, wherein the first, second, and third light emitting diodes emit light of different colors.

7. The light emitting diode circuit of claim 1, wherein the first sub-circuit and the second sub-circuit have different signal-characteristics.

8. The light emitting diode circuit of claim 7, wherein the different signal-characteristics include different minimum threshold voltages.

9. The light emitting diode circuit of claim 7, wherein the first sub-circuit comprises a plurality of first light emitting diodes and the second sub-circuit comprises a plurality of second light emitting diodes, and wherein a sum of forward voltages of the plurality of first light emitting diodes is larger than a sum of forward voltages of the plurality of second light emitting diodes.

10. The light emitting diode circuit of claim 7, wherein the first sub-circuit further comprises a threshold voltage element serially connected to the first light emitting diode.

11. A light emitting diode device comprising the light emitting diode circuit of claim 1 and further comprising a power supply (22-25) connected to the pair of terminals.

12. The light emitting diode device of claim 11, wherein the power supply comprises first and second transistors driven via a driver circuit, a first main electrode of the first transistor being coupled to one side of a voltage source, a second main electrode of the first transistor being coupled to a first main electrode of the second transistor and to one side of an inductor, a second main electrode of the second transistor being coupled to the other side of the voltage source and to one of the pair of terminals, and the other side of the inductor (25) being coupled to the other terminal of the pair of terminals.

13-14. -14. (canceled)

15. A method for controlling light emitting diodes of a light emitting diode circuit comprising (i) a first sub-circuit comprising at least one first light emitting diode and connected to a pair of terminals, and (ii) a second sub-circuit comprising at least one second light emitting diode connected to the pair of terminals in parallel with the first sub-circuit second sub-circuit further comprising a switch, the method comprises the steps of:

bringing the switch in a conducting state for switching on the second light emitting diode and switching off the first light emitting diode, and

bringing the switch in a non-conducting state for switching off the second light emitting diode and switching on the first light emitting diode.

16-17. -17. (canceled)