System and method for producing white light using LEDs

• US 20050200295A1
• Filed: 03/11/2004
• Published: 09/15/2005
• Est. Priority Date: 03/11/2004
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Ng, Kee Yean, Lee, Joon Chok, Lim, Kevin Len Li
• Granted Patent: US 7,009,343 B2
• Time in Patent Office: Days
• US Class Current: 315/150
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 1/133624 characterised by their spectral emissions
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback

Abstract

A system and method for generating white light involves using a combination of white, red, green, and blue LEDs to produce white light and adjusting the emitted light in response to feedback signals. A light system has a light source that includes at least one white LED and multiple color LEDs and a spectral feedback control system configured to detect light that is output from the light source and to adjust the light that is output from the light source in response to the light detection. The spectral feedback control system may include a color sensor configured to provide color-specific feedback signals, a controller configured to generate color-specific control signals in response to the color-specific feedback signals, and a driver configured to generate color-specific drive signals in response to the color-specific control signals.

Claims

1. A light system comprising:

a light source that includes at least one white light emitting diode (LED) and multiple color LEDs; and

a spectral feedback control system configured to detect light that is output from the light source and to adjust the light that is output from the light source in response to the light detection.

2. The light system of claim 1 wherein the spectral feedback control system is configured to control the color LEDs on a per-color basis.

3. The light system of claim 2 wherein the at least one white LED includes at least one phosphor-converted white LED and wherein the color LEDs include red, green, and blue LEDs.

4. The light system of claim 2 wherein the spectral feedback control system further includes a color sensor configured to provide color-specific feedback signals for use in controlling the colored LEDs on a per-color basis.

5. The light system of claim 4 wherein the at least one white LED is a phosphor-converted white LED.

6. The light system of claim 1 wherein the spectral feedback control system includes a controller configured to control the colored LEDs on a per-color basis to maintain luminance and chrominance characteristics of the light that is output from the light source.

7. The light system of claim 1 wherein the spectral feedback control system includes a color sensor configured to provide color-specific feedback signals.

8. The light system of claim 7 wherein the spectral feedback control system includes a controller configured to generate color-specific control signals in response to the color-specific feedback signals.

9. The light system of claim 8 wherein the spectral feedback control system includes a driver configured to generate color-specific drive signals in response to the color-specific control signals.

10. The light system of claim 1 wherein the spectral feedback control system includes:

a color sensor configured to provide color-specific feedback signals;

a controller configured to generate color-specific control signals in response to the color-specific feedback signals; and

a driver configured to generate color-specific drive signals in response to the color-specific control signals.

11. A method for operating a light system comprising:

providing drive signals to a light source that includes at least one phosphor-converted white light emitting diode (LED) and multiple color LEDs;

detecting light that is generated in response to the drive signals;

generating feedback signals in response to the detected light; and

adjusting the drive signals that are provided to the light source.

12. The method of claim 111 wherein detecting the light includes generating color-specific feedback signals.

13. The method of claim 12 wherein adjusting the drive signals includes adjusting the drive signals for the color LEDs on a per-color basis in response to the color-specific information.

14. The method of claim 13 wherein the drive signals for the color LEDs are adjusted to maintain luminance and chrominance characteristics of the detected light.

15. A light system comprising:

an LCD panel;

a light source, in optical communication with the LCD panel, which includes at least one phosphor-converted white light emitting diode (LED) and multiple color LEDs; and

a spectral feedback control system configured to detect light that is output from the light source and to adjust the light that is output from the light source in response to the light detection.

16. The LCD backlight system of claim 15 wherein the spectral feedback control system is configured to control the color LEDs on a per-color basis.

17. The LCD backlight system of claim 16 wherein the color LEDs include red, green, and blue LEDs.

18. The LCD backlight system of claim 16 wherein the spectral feedback control system further includes a color sensor configured to provide color-specific feedback signals for use in controlling the color LEDs on a per-color basis.

19. The LCD backlight system of claim 15 wherein the spectral feedback control system includes a controller configured to control the color LEDs on a per-color basis to maintain luminance and chrominance characteristics of the light that is output from the light source.

20. The LCD backlight system of claim 15 wherein the spectral feedback control system includes:

a color sensor configured to provide color-specific feedback signals;

a controller configured to generate color-specific control signals in response to the color-specific feedback signals; and

a driver configured to generate color-specific drive signals in response to the color-specific control signals.