Polarization splitting backlight module

• US 6,631,031 B2
• Filed: 11/30/2000
• Issued: 10/07/2003
• Est. Priority Date: 12/31/1999
• Status: Expired due to Fees

• Current Assignee: Chih-Kung Lee
• Original Assignee: Chih-Kung Lee
• Inventors: Wu, Chyan-Chyi, Lee, Chih-Kung, Tang, Ching-Heng
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US09/728,714
• Publication Number:
  US 20010033417A1
• Time in Patent Office: 1,041 Days
• Field of Search: 359/485, 359/487, 359/494, 359/495, 359/497, 362/31, 362/558, 362/560, 362/19, 349/61, 349/62, 349/64, 349/65, 349/67
• US Class Current: 359/485.03
• CPC Class Codes: F21V 9/14 for producing polarised light
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/285 comprising arrays of elements, e.g. microprisms
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• 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 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

A polarization splitting backlight module for efficiently emitting polarized light beams is disclosed. The polarization splitting backlight module of the present invention comprises a light source, an under plate, a substrate, a phase retardation reflective film, a scattering structure, a thin film and an upper cover. The light beams emitted from the non-polarized light source are introduced into the substrate, and after scattering, reflection, phase retardation and polarization splitting, the light beams will pass through the upper cover being of a single polarization state so as to be utilized by electro-optical systems, such as liquid crystal displays. The present invention converts light beams into a single polarization state, and thereby the efficiency of polarization splitting, as well as the brightness, are higher than that of a conventional backlight module.

Claims

1. A polarization splitting backlight module, comprising:

a substrate having a ridged upper surface and a lower surface;

a scattering structure disposed on the lower surface of the substrate;

a phase retardation film of high reflectivity, disposed under the scattering structure;

an upper cover having a ridged lower surface, substantially complementary to the upper surface of the substrate and facing therewith, and an upper surface; and

a light source located at the lateral side of the substrate.

2. The polarization splitting backlight module of claim 1, further comprising an anti-reflective film disposed on the upper surface of the upper cover.

3. The polarization splitting backlight module of claim 1, further comprising reflective films disposed on the lateral side-surface of the substrate.

4. The polarization splitting backlight module of claim 1, wherein the ridge angle between two neighboring ridges on the ridged lower surface of the upper cover is in a range from 45 degrees to 135 degrees.

5. The polarization splitting backlight module of claim 1, wherein the upper surface of the upper cover is substantially flat.

6. The polarization splitting backlight module of claim 1, wherein the phase retardation reflective film is a dry film formed by an optical-precision application process.

7. The polarization splitting backlight module of claim 1, wherein the lower surface of the substrate is substantially flat.