Liquid crystal displays with laminated diffuser plates

• US 7,710,511 B2
• Filed: 10/06/2005
• Issued: 05/04/2010
• Est. Priority Date: 10/15/2004
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Fabick, Ryan T., Ko, Byung-soo, Kim, Sang-Dae, Lee, Ji-Hwa, Kim, Ji-Hyung, Laumer, James W., Gehlsen, Mark D., Epstein, Kenneth A., Rivard, Linda M.
• Primary Examiner(s): Dudek; James A
• Application Number:
  US11/244,666
• Publication Number:
  US 20060082699A1
• Time in Patent Office: 1,671 Days
• Field of Search: 349/64, 349/98, 349/115
• US Class Current: 349/64
• CPC Class Codes: G02F 1/133507 Films for enhancing the luminance
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• 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 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 2201/086 UV absorbing

Abstract

In a liquid crystal display (LCD), for example an LCD monitor or an LCD-TV, a number of light management films, including a diffuser layer, lie between the light source and the LCD panel to provide bright, uniform illumination. In some embodiments, the diffuser layer is attached to the lower side of the LCD panel. Some, or all, of the light management layers may be attached together as a laminated stack of films. In some embodiments, the diffuser layer is formed with a recessed region on one side and another optical film positioned within the recessed region.

Claims

1. A liquid crystal display (LCD) unit, comprising:

a plurality of light sources;

an LCD panel comprising an upper plate, a lower plate and a liquid crystal layer disposed between the upper and lower plates, the lower plate facing the light source, the lower plate comprising an absorbing polarizer; and

an arrangement of light management films disposed between the plurality of light sources and the LCD panel so that the plurality of light sources illuminates the LCD panel through the arrangement of light management films, the arrangement of light management films being attached to the lower plate of the LCD panel, the arrangement of light management films comprising at least a first diffuser layers,

wherein a value of σ

/x is less than 2.5%, where x is the level of illumination light passing from the arrangement of light management films to the LCD panel, averaged across the LCD panel, and a is the root mean square deviation in the level of illumination light across the arrangement of light management films.

2. A unit as recited in claim 1, wherein the arrangement of light management films comprises at least one other layer in addition to the diffuser layer, the films of the arrangement of light management films being attached together.

3. A unit as recited in claim 2, wherein the arrangement of light management films further comprises a reflective polarizer.

4. A unit as recited in claim 2, wherein the arrangement of light management films further comprises a prismatic brightness enhancing layer.

5. A unit as recited in claim 2, wherein the arrangement of light management films further comprises a stack of least a prismatic brightness enhancing layer and a reflective polarizer.

6. A unit as recited in claim 1, wherein the arrangement of light management films provides a spatially uniform diffusion characteristic.

7. A unit as recited in claim 1, wherein diffusion for light passing through the arrangement of light management films limits the single-pass transmission to approximately 72%-95%.

8. A unit as recited in claim 7, wherein the single-pass transmission is in the range of about 85%-90%.

9. A unit as recited in claim 7, wherein the single pass transmission through the first diffuser layer and any other diffuser in the arrangement of light management films is in the range of about 72%-95%.

10. A unit as recited in claim 1, wherein the value of σ

/x is less than 2%, and the diffuser plate has a single pass transmission of at least 75%.

11. A unit as recited in claim 1, further comprising a controller coupled to control an image displayed by the LCD panel.

12. A unit as recited in claim 11, wherein the controller comprises a computer.

13. A unit as recited in claim 11, wherein the controller comprises a television controller.

14. A unit as recited in claim 1, wherein the light source is positioned to back light the LCD panel.

15. A liquid crystal display (LCD) unit, comprising:

a plurality of light sources;

an LCD panel; and

an arrangement of light management layers disposed between the plurality of light sources and the LCD panel so that the plurality of light sources illuminates the LCD panel through the arrangement of light management layers, the arrangement of light management layers comprising a diffuser plate and at least one of a brightness enhancing layer and a reflective polarizer attached together, the diffuser plate comprising a substantially transparent substrate attached to a first diffusing layer that diffuses light propagating from the one or more light sources towards the LCD panel,

wherein a value of σ

/x is less than 2.5%, where x is the level of illumination light passing from the arrangement of light management films to the LCD panel, averaged across the LCD panel, and σ

is the root mean square deviation in the level of illumination light across the arrangement of light management films.

16. A unit as recited in claim 15, wherein the at least one of a brightness enhancing layer and a reflective polarizer is attached to the diffuser plate.