Vertical alignment mode reflective-transmissive liquid crystal display with multi cell gap

• US 20050134771A1
• Filed: 11/24/2004
• Published: 06/23/2005
• Est. Priority Date: 11/27/2003
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Cha, Sung-Eun, Kim, Sang-Woo, Kim, Jae-Hyun, Lee, Jae-Young, Park, Won-Sang, Lim, Jae-Ik
• Granted Patent: US 7,528,914 B2
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence

Abstract

A vertical alignment mode reflective-transmissive liquid crystal display (LCD) includes the first substrate having an upper surface and a lower surface and the second substrate having an upper surface and a lower surface and facing the first substrate. A cell is formed between the upper surface of the first substrate and the lower surface of the second substrate. The cell has a plurality cell-gaps. A vertically aligned liquid crystal layer is disposed in the cell. The reflective region of the LCD has a cell-gap ranging from about 1.8 μm to about 2.2 μm, and the transmissive region of the LCD has a cell-gap ranging from about 3.6 μm to about 4.0 μm. The first optical film assembly including the first polarizer is disposed on the lower surface of the first substrate. The second optical film assembly including the second polarizer is disposed on the upper surface of the second substrate. An absorption axis of the first polarizer is substantially perpendicular to that of the second polarizer.

Claims

1. A liquid crystal display (LCD) having a reflective region and a transmissive region, comprising:

a first substrate having an upper surface and a lower surface;

a second substrate having an upper surface and a lower surface and facing the first substrate;

a cell formed between the upper surface of the first substrate and the lower surface of the second substrate, the cell having a plurality cell-gaps; and

a vertically aligned liquid crystal layer disposed in the cell,

wherein the reflective region has a first cell-gap ranging from about 1.8 μ

m to about 2.2 μ

m, and the transmissive region has a second cell-gap ranging from about 3.6 μ

m to about 4.0 μ

m.

2. The LCD of claim 1, wherein the first cell-gap is about 2 μ

m.

3. The LCD of claim 1, wherein the second cell-gap is about 3.8 μ

m.

4. The LCD of claim 1, wherein the LCD has a threshold voltage equal to or less than about 2.0 V.

5. The LCD of claim 4, wherein the threshold voltage is about 1.7 V.

6. The LCD of claim 4, wherein the LCD has a saturation voltage equal to or less than about 4.4 V.

7. The LCD of claim 6, wherein the saturation voltage is about 4.0 V.

8. The LCD of claim 1, further comprising:

a first optical film assembly disposed on the lower surface of the first substrate and comprising a first polarizer; and

a second optical film assembly disposed on the upper surface of the second substrate and comprising a second polarizer,

wherein an absorption axis of the first polarizer is substantially perpendicular to that of the second polarizer.

9. The LCD of claim 8, wherein the first optical film assembly comprises:

a first λ

/4 retardation film disposed on the lower surface of the first substrate;

a first λ

/2 retardation film disposed on the first λ

/4 retardation film; and

the first polarizer disposed on the first λ

/2 retardation film.

10. The LCD of claim 9, wherein the second optical film assembly comprises:

a second λ

/4 retardation film disposed on the upper surface of the second substrate;

a second λ

/2 retardation film disposed on the second λ

/4 retardation film; and

the second polarizer disposed on the second λ

/2 retardation film.

11. The LCD of claim 10, wherein a slow axis of the second λ

/4 retardation film is slanted at an angle of about 15°

counterclockwise with respect to the absorption axis of the second polarizer.

12. The LCD of claim 10, wherein a slow axis of the second λ

/2 retardation film is slanted at an angle of about 75°

counterclockwise with respect to the absorption axis of the second polarizer.

13. The LCD of claim 11, wherein a slow axis of the first λ

/4 retardation film and the slow axis of the second λ

/4 retardation film form an angle ranged from about 80°

to about 100.

14. The LCD of claim 13, wherein the slow axis of the first λ

/4 retardation film is substantially perpendicular to that of the second λ

/4 retardation film.

15. The LCD of claim 12, wherein a slow axis of the first λ

/2 retardation film and the slow axis of the second λ

/2 retardation film form an angle ranged from about 80°

to about 100°

.

16. The LCD of claim 15, wherein the slow axis of the first λ

/2 retardation film is substantially perpendicular to that of the second λ

/2 retardation film.

17. The LCD of claim 10, wherein the second optical film assembly further comprises a compensation film formed between the second substrate and the second λ

/4 retardation film.

18. The LCD of claim 17, wherein the compensation film is an A-plate or a C-plate.

19. The LCD of claim 1, wherein the vertically aligned liquid crystal layer comprises liquid crystal having a pre-tilt angle equal to or greater than about 45°

.

20. The LCD of claim 1, further comprising a backlight assembly disposed below the lower surface of the first substrate.