LED backlight using discrete RGB phosphors

• US 20080116468A1
• Filed: 11/22/2006
• Published: 05/22/2008
• Est. Priority Date: 11/22/2006
• Status: Abandoned Application

• Current Assignee: Gelcore (General Electric Company)
• Original Assignee: Gelcore (General Electric Company)
• Inventors: Soules, Thomas F., Stadelman, Larry, Radkov, Emil Vergilov
• Application Number:
  US11/603,804
• Publication Number:
  US 20080116468A1
• Time in Patent Office: Days
• US Class Current: 257/89
• 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 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence

Abstract

An LED backlight apparatus includes a plurality of radiation emitting diodes, each diode emits radiation having a peak wavelength of about less than 430 nm. Each diode is located on a back surface of a housing. The housing may have an opening. A screen covers the opening and the screen includes a discrete pattern of phosphor coated red light emitting pixels, a second discrete pattern of phosphor coated green light emitting pixels, and a third discrete pattern of phosphor coated blue light emitting pixels. The emitted radiation may excite the phosphor coated pixels. The apparatus may also include a radiation regulating element proximate the screen and further include a diffuser proximate the diodes.

Claims

1. A diode backlight apparatus comprising:

a plurality of radiation emitting diodes, each emits radiation having a peak wavelength of about less than 430 nm, located on a back surface of a housing;

the housing having an opening;

a screen covering the opening, the screen includes a discrete pattern of phosphor coated red light emitting pixels, a second discrete pattern of phosphor coated blue light emitting pixels, and a third discrete pattern of phosphor coated green light emitting pixels;

a radiation regulating element proximate the screen; and

a diffuser proximate the diodes.

2. The apparatus of claim 1 wherein the radiation regulating element comprises a shutter.

3. The apparatus of claim 2 wherein the shutter comprises a type of shutter selected from the group of mechanical shutter, digital light processor, micro-electro-mechanical system and electro-optical shutter.

4. The apparatus of claim 1 wherein the radiation regulating element comprises an actuated polarizing filter.

5. The apparatus of claim 1 wherein the diffuser comprises a refractory diffuser.

6. The apparatus of claim 1 wherein the red light emitting pixels, the green light emitting pixels, and the blue light emitting pixels comprise a plurality of pixels and a ratio of the plurality of diodes to the plurality of pixels comprises less than about 1:

1.

7. The apparatus of claim 1 further comprising a UV filter located above the screen.

8. The apparatus of claim 1 wherein the apparatus having a thickness of less than about seven (7) inches.

9. The apparatus of claim 1 wherein the diodes comprise power LEDs.

10. The apparatus of claim 1 wherein the phosphor coated pixels further include one or more pigments.

11. The apparatus of claim 1 wherein a peak wavelength of the one or more pixels of the discrete pattern of red light emitting pixels comprises between about 610 nm to about 660 nm.

12. The apparatus of claim 11 wherein red light emitting pixels comprise a material selected from oxysulfides doped with Eu³⁺, oxyfluorides doped with Mn⁴⁺, complex fluorides doped with Mn⁴⁺, nitridosilicates doped with Eu²⁺, and combinations thereof.

13. The apparatus of claim 12 wherein the material has the chemical formula of at least one of 3.5MgO*0.5MgF₂*GeO₂:

Mn⁴⁺, La₂O₂S;

Eu³⁺, K₂[TiF₆];

Mn⁴⁺, CaAlSiN₃;

Eu²⁺, and combinations thereof.

14. The apparatus of claim 1, wherein a peak wavelength of the one or more pixels of the discrete pattern of green light emitting pixels comprises between about 500 nm to about 560 nm.

15. The apparatus of claim 14 wherein the green light emitting pixels comprise a material selected from thiogallates doped with Eu²⁺, silicates doped with Eu²⁺, sulfides doped with Cu⁺, aluminates doped with Eu²⁺, and combinations thereof.

16. The apparatus of claim 15 wherein the material comprises one selected from SrGa₂S₄:

Eu²⁺, Ba₂SiO₄;

Eu²⁺, ZnS;

Cu⁺, SrAl₂O₄;

Eu²⁺ and BaMgAl₁₀O₁₇;

Eu²⁺, Mn²⁺, and combinations thereof.

17. The apparatus of claim 1 wherein a peak wavelength of the one or more pixels of the discrete pattern of blue light emitting pixels comprises between about above 440 nm to about 470 nm.

18. The apparatus of claim 17 wherein the blue light emitting pixels comprise a material selected from halophosphates doped with Eu²⁺, sulfides doped with Ag⁺, BaMgAl₁₀O₁₇:

Eu²⁺, and combinations thereof.

19. The apparatus of claim 18 wherein the material comprises one selected from Sr₅(PO₄)₃Cl:

Eu²⁺, ZnS;

Ag⁺, and combinations thereof with or without BaMgAl₁₀O₁₇;

Eu²⁺.

20. The apparatus of claim 1 wherein a transmittance of the diffuser comprises at least about 80%.

21. The apparatus of claim 1 wherein the peak wavelength comprises a wavelength in a range of 390 to 420 nm.

22. The apparatus of claim 1 wherein the screen includes a mask around the discrete pattern of red, green, and blue emitting pixels.

23. A diode backlight apparatus comprising:

a plurality of radiation emitting diodes, each diode emits radiation having a peak wavelength of about less than 430 nm, located on a back surface of a housing;

the housing having a thickness of about five (5) inches or less and an opening;

a screen covering the opening, the screen includes a discrete pattern of phosphor coated red light emitting pixels, a second discrete pattern of phosphor coated blue light emitting pixels, and a third discrete pattern of phosphor coated green light emitting pixels;

a radiation regulating element proximate the screen, and

a diffuser proximate the diodes.

24. A LED backlight apparatus comprising:

a plurality of LEDs, each LED having a peak wavelength of about less than 430 nm, located on a back surface of a housing;

the housing having an opening;

a screen covering the opening, the screen includes a discrete pattern of phosphor coated red light emitting pixels, a second discrete pattern of phosphor coated green light emitting pixels, and a third discrete pattern of phosphor coated blue light emitting pixels; and

a radiation regulating element proximate the screen.