Liquid crystal display

• US 20060290846A1
• Filed: 05/24/2006
• Published: 12/28/2006
• Est. Priority Date: 06/24/2005
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Jae-Hyun
• Granted Patent: US 7,750,995 B2
• Time in Patent Office: Days
• US Class Current: 349/113
• CPC Class Codes: G02F 1/133541 Circular polarisers
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 2203/01 transmissive
• CPC Class Codes: G02F 2203/09 transflective

Abstract

Disclosed is a liquid crystal display. In the LCD, a reflective polarizer and an optical retarder are provided between an absorbing polarizer and a backlight unit. This structure recycles light that would ordinarily be removed by absorption in conventional LCDs to be used for the display, so that light efficiency and display luminance of the LCD may be improved.

Claims

1. A liquid crystal display comprising:

a display panel;

a reflective polarizer provided under the display panel transmitting light that is linearly polarized in a first direction and reflecting light that is linearly polarized in a second direction perpendicular to the first direction;

an optical retarder provided under the reflective polarizer; and

a backlight unit provided under the optical retarder, said backlight unit comprising a light source for supplying light to the display panel, wherein the reflective polarizer includes a substrate and a plurality of metal lines formed on a surface of the substrate, and an interval between two adjacent metal lines is narrower than a wavelength of visible light supplied by the backlight unit, and

the metal lines of the reflective polarizer are parallel to each other in the second direction.

2. The liquid crystal display of claim 1, further comprising a first absorbing polarizer provided between the display panel and the reflective polarizer.

3. The liquid crystal display of claim 2, wherein a transmission axis of the first absorbing polarizer is in the first direction.

4. The liquid crystal display of claim 3, further comprising a second absorbing polarizer coupled to an upper surface of the display panel.

5. The liquid crystal display of claim 4, wherein a transmission axis of the second absorbing polarizer is in the second direction.

6. The liquid crystal display of claim 1, wherein the optical retarder has a slow axis and a fast axis, and a phase difference between the two axes is a quarter-wave for converting circularly polarized light into linearly polarized light or linearly polarized light into circularly polarized light.

7. The liquid crystal display of claim 6, wherein the fast axis or the slow axis of the optical retarder is formed at angle of ±

45°

relative to the first direction or the second direction.

8. The liquid crystal display of claim 1, wherein the backlight unit includes a reflective plate for reflecting light toward the display panel.

9. A liquid crystal display comprising:

a display panel;

a reflective polarizer provided under the display panel transmitting light that is linearly polarized in a first direction and reflecting light that is linearly polarized in a second direction perpendicular to the first direction; and

a backlight unit provided under the reflective polarizer, said backlight unit comprising a light source for supplying light to the display panel,

wherein the reflective polarizer includes a substrate, a plurality of metal lines, and an optical retardation film formed under the metal lines, and

wherein the metal lines are parallel to each other in the second direction, and an interval between two adjacent metal lines is narrower than a wavelength of visible light supplied by the backlight unit.

10. The liquid crystal display of claim 9, further comprising a first absorbing polarizer provided between the display panel and the reflective polarizer.

11. The liquid crystal display of claim 10, wherein a transmission axis of the first absorbing polarizer is in the first direction.

12. The liquid crystal display of claim 11, further comprising a second absorbing polarizer coupled to an upper surface of the display panel.

13. The liquid crystal display of claim 12, wherein a transmission axis of the second absorbing polarizer is in the second direction.

14. The liquid crystal display of claim 9, wherein the optical retardation film has a slow axis and a fast axis, and a phase difference between the two axes is a quarter-wave for converting circularly polarized light into linearly polarized light or linearly polarized light into circularly polarized light.

15. The liquid crystal display of claim 14, wherein the fast axis or the slow axis of the optical retardation film is formed at an angle of ±

45°

relative to the first direction or the second direction.

16. The liquid crystal display of claim 15, wherein the substrate of the reflective polarizer is placed on the plurality of metal lines or under the optical retardation film.

17. The liquid crystal display of claim 9, wherein the optical retardation film is obtained by curing liquid crystal.

18. The liquid crystal display of claim 9, wherein the backlight unit further includes a reflective plate for reflecting light toward the display panel.