Backlight device for dual-view display

• US 20090103008A1
• Filed: 09/26/2008
• Published: 04/23/2009
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: TPO Displays Corporation (InnoLux Corporation)
• Inventors: Louwsma, Hendrik, Nasu, Kousuke
• Granted Patent: US 8,363,181 B2
• Time in Patent Office: Days
• US Class Current: 349/64
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

The present invention provides a backlight for dual-view display, comprising: a light source; a light-guide plate, which allows the incoming of light from the light source and uniformly guides and diffuses the light; a diffusing sheet, which is placed between the light-guide plate and liquid crystal panel; two prism sheets, which are placed between the diffusing sheet and the liquid crystal panel; and a reflective sheet, wherein the face where the prism is formed on the prism sheet on the diffusing sheet side amongst the two prism sheets faces the diffusing sheet, and the prism axis (the ridge line of the prism) is placed as to be parallel to a longitudinal direction with respect to the liquid crystal screen; the face where the prism is formed on the prism sheet on the liquid crystal panel side faces the liquid crystal panel, and the prism axis (the ridge line of the prism) is placed as to be the same as the lateral directions with respect to the liquid crystal screen; the prism tip angle of the prism sheet on the diffusing sheet side is 80° to 95°, and the prism tip angle of the prism sheet on the liquid crystal panel side is 70° to 100°.

Claims

1. A backlight device for a dual-view display having a liquid crystal panel and showing a liquid crystal screen, comprising:

a light source;

a light-guide plate guiding and diffusing a light from the light source

a diffusing sheet disposed between the light-guide plate and the liquid crystal panel;

a first prism sheet and a second prism sheet disposed between the diffusing sheet and the liquid crystal panel, wherein the first prism sheet has a prism forming surface facing the diffusing sheet and the second prism sheet has a prism forming surface facing the liquid crystal panel; and

a reflective sheet;

wherein the first prism sheet has a prism axis parallel to a longitudinal direction of the liquid crystal screen and has a tip angle ranged from 80°

to 95°

, and the second prism sheet has a prism axis parallel to a lateral direction of the liquid crystal screen and has a tip angle ranged from 70°

to 110°

.

2. The backlight device according to claim 1, wherein the tip angle of the first prism sheet is ranged from 89°

to 90°

.

3. The backlight device according to claim 1, wherein the tip angle of the second prism sheet is ranged from 80°

to 100°

.

4. The backlight device according to claim 1, wherein the first and second prism sheets have a respective plane surface facing to each other, and either one or both of the surfaces are matte-finished.

5. The backlight device according to claim 4, wherein the surface of the first prism sheet is matte-finished.

6. The backlight device according to claim 1, wherein the dual-view display further includes a polarizer having a transmission axis, and the first prism sheet and the second prism sheet are disposed in such a way that the respective prism axes thereof are orthogonal to each other and are rotated an angle ranged from ±

35′

to ±

45′

with respect to the transmission axis of the polarizer.

7. The backlight device according to claim 6, wherein the polarizer is a polarizer of reflective type.

8. A liquid crystal display device comprising the backlight device according to any of claims 1 to 7.

9. An automotive dual-view display using the liquid crystal display device of claim 8.