Flat panel energized by blue LED for generating white light

• US 7,248,310 B2
• Filed: 11/30/2004
• Issued: 07/24/2007
• Est. Priority Date: 04/04/2001
• Status: Expired due to Fees

• Current Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Inventors: Mueller-Mach, Regina, Mueller, Gerd O.
• Primary Examiner(s): Lebentritt; Michael
• Assistant Examiner(s): Roman; Angel
• Application Number:
  US11/001,278
• Publication Number:
  US 20050104076A1
• Time in Patent Office: 966 Days
• Field of Search: 349/61, 349/62, 349/70, 349/71
• US Class Current: 349/71
• CPC Class Codes: G02F 1/133617 Illumination with ultraviolet light; Luminescent elements or materials associated to the cell
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence

Abstract

A color, transmissive LCD uses a backlight that supplies a uniform blue light to the back of the liquid crystal layer in an LCD. The blue light, after being modulated by the liquid crystal layer, is then incident on the back surface of phosphor material located above the liquid crystal layer. A first phosphor material, when irradiated with the blue light, generates red light for the red pixel areas of the display, and a second phosphor material, when irradiated with the blue light, generates green light for the green pixel areas of the display. No phosphor is deposited over the blue pixel areas.

Claims

1. A light producing device comprising:

an LED that emits visible blue light of a first wavelength; and

a substantially flat plate separated from the LED and receiving light from the LED, the plate comprising a first phosphor material that converts the light of the first wavelength to red light, and having a second phosphor material that converts the light of the first wavelength to green light,

the plate having a surface area receiving light from the LED that is larger than a light emitting surface area of the LED,

the plate allowing the light of the first wavelength to pass through so that the red, green, and blue light are emitted by the plate to create colors with visible red, green, and blue components.

2. The device of claim 1 wherein the first wavelength includes 460 nm.

3. The device of claim 1 wherein a combination of the red, green, and blue light produces white light.

4. The device of claim 1 further comprising a liquid crystal device for modulating at least the blue light.

5. The device of claim 1 wherein the first phosphor material and the second phosphor material are deposited an the plate in a pattern.

6. The device of claim 1 wherein the plate has areas where there is no phosphor deposited to allow the blue light to pass through.

7. The device of claim 1 wherein the plate provides diffusion of the blue light.

8. The device of claim 1 further comprising a light guide having an edge, and wherein the LED is optically coupled to the edge of the light guide, the light guide having diverters that divert the blue light to impinge upon the plate.

9. The device of claim 8 further comprising lenses on the light guide to collimate a light output from the light guide.

10. The device of claim 1 wherein the light producing device forms a display in a television.

11. The device of claim 1 wherein the light producing device forms a display in a cell phone.

12. The device of claim 1 wherein there is no phosphor on the plate for converting the visible blue light to a different wavelength of visible blue light.

13. The device of claim 1 wherein a combination of the red, green, and blue light produces colors with any combination of red, green, and blue components.

14. The device of claim 1 further comprising a plurality of LEDs that emit visible blue light of the first wavelength.

15. A method of generating light with visible red, green, and blue components comprising:

energizing an LED that cmits visible blue light of a first wavelength; and

irradiating a substantially flat plate separated from the LED with light from the LED, the plate comprising a first phosphor material that converts the light of the first wavelength to red light, and having a second phosphor material that converts the light of the first wavelength to green light, the plate having a surface area receiving light from the LED that is larger than a light emitting surface area of the LED, the plate allowing the light of the first wavelength to pass through so that the red, green, and blue light are emitted by the plate to create colors with visible red, green, and blue components.

16. The method of claim 15 wherein the first wavelength includes 460 nm.

17. The method of claim 15 wherein a combination of the red, green, and blue light produces white light.

18. The method of claim 15 further comprising modulating at least the blue light with a liquid crystal device.

19. The method claim 15 wherein the first phosphor material and the second phosphor material are deposited on the plate in a pattern.

20. The method of claim 15 wherein the plate has areas where there is no phosphor deposited to allow the blue light to pass through.

21. The method of claim 15 wherein the plate provides diffusion of the blue light.