Laser illuminated backlight for flat panel displays

• US 7,866,869 B2
• Filed: 10/27/2008
• Issued: 01/11/2011
• Est. Priority Date: 10/27/2008
• Status: Active Grant

• Current Assignee: Corporation For Laser Optics Research, Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Corporation For Laser Optics Research
• Inventors: Karakawa, Masayuki
• Primary Examiner(s): Alavi, Ali
• Application Number:
  US12/259,000
• Publication Number:
  US 20090109658A1
• Time in Patent Office: 806 Days
• Field of Search: 362/231, 362/612, 362/613, 349/62, 349/65
• US Class Current: 362/613
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays

Abstract

Laser lit flat panel displays are disclosed including edge-lit and direct lit backlights. In certain embodiments, laser assemblies are selected to obtain bandwidth distributions to reduce speckle.

Claims

1. A flat panel display, comprising:

a backlight including a plurality of lasing elements of at least two primary colors arranged in a plurality of laser assemblies, wherein;

the backlight comprises a light guide for substantially distributing light output by the plurality of laser assemblies across the flat panel display,

the plurality of laser assemblies are positioned about an exterior edge of the light guide,

the plurality of lasing elements of at least one of the three primary colors are selected such that each lasing element emits a laser beam with a center wavelength λ

_0i and a spectral bandwidth Δ

λ

_i,

the center wavelength of at least one of the lasing elements is wavelength-shifted with respect to the center wavelength of at least one other lasing element, and

said laser beams, when combined, have an ensemble spectrum Λ

with an overlap parameter γ

= Δ

λ

_i/ S_i with Δ

λ

_i being a mean spectral bandwidth of the lasing elements and S_i being a mean wavelength shift between the center wavelengths λ

_0i of the at least one and the at least one other lasing elements, with Δ

λ

_i and S_i selected such that γ

≧

1; and

an array of light modulators arranged across the flat panel display for modulating light emitted by the backlight.

2. The flat panel display of claim 1, wherein each laser assembly includes at least one lasing element of each primary color.

3. The flat panel display of claim 1, wherein at least one laser assembly includes a plurality of lasing elements of at least one primary color.

4. The flat panel display of claim 1, wherein the light modulators comprise a liquid crystal display (LCD) panel.

5. The flat panel display of claim 1, comprising diffusion optics corresponding to the plurality of laser assemblies.

6. The flat panel display of claim 1, wherein the plurality of laser assemblies are positioned about each exterior edge of the light guide.

7. The flat panel display of claim 1, wherein the plurality of laser assemblies are positioned at corners of the light guide.

8. The flat panel display of claim 1, wherein the plurality of laser assemblies are arranged about the light guide in a plurality of rows.

9. The flat panel display of claim 8, wherein each row of laser assemblies is configured for independent control with respect to laser assemblies in at least one other row.

10. The flat panel display of claim 9, wherein the laser assemblies are configured such that the brightness of at least one color within at least one laser assembly can be controlled independently of other colors in the laser assembly.

11. The flat panel display of claim 8, comprising a plurality of additional light guides, wherein each light guide corresponds to a row of laser assemblies.

12. The flat panel display of claim 11, comprising reflective separators positioned between the plurality of light guides.