Flat panel display lighting system

• US 5,461,547 A
• Filed: 07/20/1993
• Issued: 10/24/1995
• Est. Priority Date: 07/20/1993
• Status: Expired due to Term

• Current Assignee: Credit Managers Association Of California
• Original Assignee: Precision Lamp, Inc. (Lumen Technologies, Inc.)
• Inventors: Ciupke, Werner W., DuNah, Richard E., Redmond, William F.
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): Cariaso, Alan B.
• Application Number:
  US08/095,753
• Time in Patent Office: 826 Days
• Field of Search: 359/40, 359/41, 359/48, 359/49, 359/50, 359/64, 359/70, 362/26, 362/27, 362/31, 362/293, 362/327, 362/330, 362/390
• US Class Current: 362/617
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A flat panel display lighting system is disclosed wherein a thin, flat light guide has two spaced major surfaces with light introduced into one edge of the guide. Light is extracted from the light guide by the facets in a plurality of parallel microgrooves disposed to intersect the light introduced into the light guide. A liquid crystal display is placed adjacent to the light guide to be backlit or frontlit.

Claims

1. A thin, large-area lighting system comprising:

a thin, transparent, rectangular light guide having first and second parallel major surfaces, said first major surface having a plurality of uniform, spaced v-shaped parallel microgrooves each extending continuously across a substantial portion of said first major surface and a plurality of planar surface portions between said microgrooves, said light guide having a uniform thickness, said microgrooves having a longitudinal axis;

means for introducing light into said light guide from at least one edge in a direction generally perpendicular to said longitudinal axis of said microgrooves,

said microgrooves having surfaces which form an angle with respect to the first major surface which, when taken together with the index of refraction of the material of said light guide, internally reflects substantially all the light striking said surfaces of said microgrooves toward the second major surface at a first angle of incidence for emission from said second major surface,

said planar surface portions being configured for internally reflecting a substantial portion of light striking said planar surface portions toward said second major surface at a second angle of incidence for internal reflection by said second major surface along said light guide.

2. A thin, large-area lighting system as in claim 1 including reflective means adjacent to said first major surface for reflecting light which leaves the light guide back into the light guide and toward said second major surface to enhance the emitted light intensity.

4. A thin large area lighting system as in claims 1, 2 or 3 wherein the angle formed by said microgroove surfaces is between 45-55 degrees with respect to a direction perpendicular to the first major surface.

5. A lighting system as in claim 4 wherein the grooves microgrooves are equally spaced.

6. A thin, large-area lighting system as in claim 1 in which the light guide material is tinted for the desired light color.

7. A lighting system as in claims 1, 2 or 3 wherein the thickness of the light guide is approximately 1 mm and the depth of the microgrooves is between 2.5-10 μ

m with the spacing between microgrooves between 100-250 μ

m.

8. A lighting system as in claims 1, 2 or 3 wherein said means for introducing light into said light guide comprises:

an elongated, incandescent lamp adjacent to said one edge,

a reflector extending from the edge of the light guide around said incandescent lamp to reflect light from said lamp into the light guide, and

a flexible transparent material substantially filling the space between said lamp, said reflector and the edge of said light guide serving to cushion the lamp against shock and efficiently couple the light into the light guide.

9. A lighting system as in claim 8 wherein the flexible transparent material is tinted to provide colored light.

3. A thin, large-area lighting system comprising:

a thin, transparent, rectangular light guide having first and second parallel major surfaces, said first major surface having a plurality of uniform, spaced v-shaped parallel microgrooves extending continuously across a substantial portion of said first major surface and a plurality of planar surface portions between said microgrooves, said microgrooves having a longitudinal axis;

means for introducing light into said light guide from at least one edge in a direction generally perpendicular to said longitudinal axis of said microgrooves,

said microgrooves having surfaces which form an angle with respect to the first major surface which, when taken together with the index of refraction of the material of said light guide, internally reflects substantially all the light within said light guide toward the second major surface at a first angle of incidence for emission from said second major surface,

said planar surface portions being configured for internally reflecting a substantial portion of light striking said planar surface portions toward said second major surface at a second angle of incidence for internal reflection by said second major surface along said light guide, and

reflecting means adjacent to said second major surface for reflecting light toward said first major surface where the reflected light is emitted from said first major surface between said microgrooves.

10. An illuminated LCD system including a thin, large-area lighting system comprising:

a thin, transparent, rectangular light guide having first and second parallel major surfaces, said first major surface having a plurality of v-shaped parallel microgrooves extending across said first major surface, said microgrooves having a longitudinal axis;

means for introducing light into said light guide from at least one edge in a direction generally perpendicular to said longitudinal axis of said microgrooves;

said microgrooves having surfaces which form an angle with respect to the first major surface which, when taken together with the index of refraction of the material of said light guide, internally reflects substantially all the light within said light guide toward the second major surface for emission from said second major surface; and

a front-lit LCD having a front surface in contact with said second major surface and a reflecting back surface which reflects light introduced into the front surface to display information in the display, whereby the display is illuminated from the front and the display information is viewed through the light guide.

11. An illuminated LCD system comprising:

a thin, transparent, rectangular light guide having first and second parallel major surfaces, said first major surface having a plurality of spaced v-shaped parallel microgrooves extending continuously across a substantial portion of said first major surface and a plurality of planar surface portions between said microgrooves, said light guide being of a uniform thickness, said microgrooves having a longitudinal axis;

means for introducing light into said light guide from at least one edge in a direction generally perpendicular to said longitudinal axis of said microgrooves;

said microgrooves having a uniform configuration with each of said microgrooves having surfaces which form an angle with respect to said first major surface which, when taken together with the index of refraction of the material of said light guide, internally reflects substantially all the light striking said surfaces of said microgrooves toward the second major surface at a first angle of incidence for emission from said second major surface;

said planar surface portions being configured for internally reflecting a substantial portion of light striking said planar surface portions toward said second major surface at a second angle of incidence for internal reflection by said second major surface along said light pipe; and

a backlit LCD placed with the back surface of said LCD adjacent to said second major surface.

12. An illuminated LCD system as in claim 11 wherein a diffuser is placed between said second major surface and said LCD.

13. An illuminated LCD system as in claim 11 wherein the LCD is transmissive.

14. An illuminated LCD system as in claim 11 including reflective means adjacent to said first major surface for reflecting light which leaves the light guide back into the light guide and toward said second major surface to enhance the emitted light intensity.

15. An illuminated LCD system comprising:

a thin, transparent, rectangular light guide having first and second parallel major surfaces, said first major surface having a plurality of v-shaped parallel microgrooves extending continuously across a substantial portion said first major surface and a plurality of planar surface portions between said microgrooves, said microgrooves having a longitudinal axis;

means for introducing light into said light guide from at least one edge in a direction generally perpendicular to said longitudinal axis of said microgrooves;

said microgrooves having a uniform shape and size with each of said microgrooves having surfaces which form an angle with respect to said first major surface which, when taken together with the index of refraction of the material of said light guide, internally reflects substantially all the light within said light guide toward the second major surface at a first angle of incidence for emission from said second major surface;

said planar surface portions being configured for internally reflecting a substantial portion of light striking said planar surface portions toward said second major surface at a second angle of incidence for internal reflection by said second major surface along said light guide, and

a backlit LCD placed with the back surface of said LCD adjacent to said first major surface; and

reflecting means adjacent to said second major surface for reflecting light emitted from the second major surface toward said first major surface for emission from said first major surface between said microgrooves where the reflected light illuminates the LCD.

16. An illuminated LCD system as in claim 15 wherein a diffuser is placed between said first major surface and said LCD.

17. An illuminated LCD system as in claim 16 wherein the LCD is transmissive.