Method for maintaining ligh characteristics from a multi-chip LED package

• US 20030234342A1
• Filed: 06/25/2002
• Published: 12/25/2003
• Est. Priority Date: 06/25/2002
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Gaines, James M., Pashley, Michael D.
• Granted Patent: US 6,998,594 B2
• Time in Patent Office: Days
• US Class Current: 250/205
• CPC Class Codes: H05B 45/22 using optical feedback

Abstract

The present invention provides a method, system and structure for maintaining light characteristics from a multi-chip LED package. This may be done by selecting a desired light output and restricting light from a plurality of light emitting diodes in the multi-chip LED package. It may also be done by measuring the restricted light, comparing the measured output light to the desired light and by adjusting current to LEDs in the multi-chip LED package based on the measured light.

Claims

1. A method for maintaining light characteristics from a multi-chip light emitting diode (LED) package, comprising:

restricting transmitted light to at least one light sensor to produce a restricted light signal;

measuring the restricted light signal by the at least one light sensor to produce a sensed light signal;

comparing the sensed light signal to a desired light signal; and

adjusting current to at least one light emitting diode on the multi-chip LED package based on the comparison.

2. The method of claim 1, further comprising:

providing a desired light signal to a control device via an input device.

3. The method of claim 1, wherein the light sensor is selected from a group consisting of a photodiode and a photoconductor.

4. The method of claim 3, wherein the light sensor is filtered.

5. The method of claim 1, wherein restricting the transmitted light comprises positioning the at least one light sensor within an enclosure.

8. The method of claim 1, wherein the light emitting diodes within the multi-chip LED package comprise a plurality of light emitting diodes emitting red, green and blue light.

9. The method of claim 8, wherein the light sensor is unfiltered.

10. The method of claim 9, wherein measuring the transmitted light by the at least one light sensor comprises a time multiplex sampling.

11. The method of claim 1, wherein adjusting the current comprises adjusting the current to selected light emitting diodes using a control system.

12. The method of claim 1 further comprising:

measuring the temperature within the multi-chip LED package;

comparing the measured temperature to a desired temperature; and

adjusting the current to the at least one LED based on the comparison.

6. The method of claim 6, wherein the enclosure includes at least one aperature.

7. The method of claim 6, wherein the enclosure includes a white interior wall.

13. A system for maintaining light characteristics from a multi-chip light emitting diode (LED) package, comprising:

means for restricting transmitted light to at least one light sensor to produce a restricted light signal;

means for measuring the restricted light signal by the at least one light sensor to produce a sensed light signal;

means for comparing the sensed light signal to a desired light signal; and

means for adjusting current to at least one light emitting diode on the multi-chip LED package based on the comparison.

14. The system of claim 13, further comprising:

means for providing a desired light signal to a control device via an input device.

15. The system of claim 13, further comprising:

means for measuring the temperature within the multi-chip LED package;

means for comparing the measured temperature to a desired temperature; and

means for adjusting the current to the at least one LED based on the comparison.

16. A structure for maintaining light characteristics from a multi-chip light emitting diode (LED) package, comprising:

a plurality of LEDs;

at least one enclosure positioned to receive an amount of light output from the plurality of LEDs;

at least one light sensor positioned in the enclosure to measure the light output from the plurality of LEDs; and

a controller operably connected to the LED chips to control current to the LED chips based on the measured light.

17. The structure of claim 16, further comprising:

at least one temperature sensor; and

a controller operably connected to the LED chips to control current to the LED chips based on the measured temperature.