System and method for producing white light using a combination of phosphor-converted with LEDs and non-phosphor-converted color LEDs

• US 20060066266A1
• Filed: 11/14/2005
• Published: 03/30/2006
• Est. Priority Date: 03/11/2004
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Ng, Kee Yean, Lee, Joon Chok, Li Lim, Kevin Len
• Granted Patent: US 7,256,557 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: G02F 1/133603 with LEDs
• 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: G02F 2201/58 Arrangements comprising a monitoring photodetector
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• 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 phosphor-converted white LEDs and non-phosphor-converted color LEDs to produce white light and adjusting the emitted light in response to feedback signals. Generating white light using a combination of phosphor-converted white LEDs and non-phosphor-converted color LEDs produces white light with an improved CRI and a wide SPD. Adjusting the emitted light in response to feedback allows luminance and chrominance characteristics of the white light to be controlled as the performance of the LEDs changes over time. The emitted light can be adjusted on a per-color basis and/or on a per-group basis, where a group of LEDs includes a combination of at least one phosphor-converted white LED and at least one non-phosphor-converted color LED.

Claims

1. A light system comprising:

a light source that includes at least one phosphor-converted white light emitting diode (LED) and at least one non-phosphor-converted color LED; and

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

2. The light system of claim 1 wherein the at least one phosphor-converted white LED comprises an LED that emits white or off-white light.

3. The light system of claim 2 wherein the at least one non-phosphor-converted color LED comprises an LED that emits one of red, green, blue, cyan, and amber light.

4. The light system of claim 1 wherein the spectral feedback control system further includes a color sensor configured to provide color-specific feedback signals for use in controlling the LEDs.

5. The light system of claim 1 wherein the spectral feedback control system further includes a color sensor configured to provide color-specific feedback signals for use in controlling the non-phosphor-converted color LEDs on a per-color basis.

6. The light system of claim 1 wherein the spectral feedback control system further includes a color sensor configured to provide color-specific feedback signals for use in controlling the LEDs on a per-group basis.

7. The light system of claim 6 wherein a group comprises a combination of at least one phosphor-converted white LED and at least one non-phosphor-converted color LED.

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

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

10. The light system of claim 9 wherein a group comprises a combination of at least one phosphor-converted white LED and at least one non-phosphor-converted color LED.

11. 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 control signals in response to the color-specific feedback signals; and

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

12. 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.

13. 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 group-specific control signals in response to the color-specific feedback signals; and

a driver configured to generate group-specific drive signals in response to the group-specific control signals;

wherein a group comprises a combination of at least one phosphor-converted white LED and at least one non-phosphor-converted color LED.

14. 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 at least one non-phosphor-converted color LED to generate white light;

detecting the white 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 in response to the feedback signals.

15. The method of claim 14 wherein generating feedback signals comprises generating color-specific feedback signals.

16. The method of claim 15 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 feedback signals.

17. The method of claim 15 wherein adjusting the drive signals includes adjusting the drive signals for the LEDs on a per-group basis in response to the color-specific feedback signals.

18. The method of claim 14 wherein adjusting the drive signals includes adjusting the drive signals for the LEDs on a per-group basis in response to the color-specific feedback signals, wherein a group comprises a combination of at least one phosphor-converted LED and at least one non-phosphor-converted color LED.

19. 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 at least one non-phosphor-converted color LED; and

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

20. The light system of claim 19 wherein the at least one phosphor-converted LED comprises an LED that emits white or off-white light.

21. The light system of claim 20 wherein the at least one non-phosphor-converted color LED comprises an LED that emits one of red, green, blue, cyan, and amber light.

22. The light system of claim 21 wherein the spectral feedback control system is configured to control the color LEDs on a per-color basis.

23. The light system of claim 21 wherein the spectral feedback control system is configured to control the LEDs on a per-group basis, wherein a group comprises a combination of at least one phosphor-converted white LED and at least one non-phosphor-converted color LED.