Transflective liquid crystal display device

• US 20030223022A1
• Filed: 04/07/2003
• Published: 12/04/2003
• Est. Priority Date: 04/17/2000
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Baek, Heum-Il
• Granted Patent: US 7,307,680 B2
• Time in Patent Office: Days
• US Class Current: 349/113
• 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 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n

Abstract

A transflective LCD device improves a light transmittance in both the transmissive mode and the reflective mode and improves efficiency in the use of the light regardless of wavelength. To properly control the ON/OFF-switch of the blue wavelength band or the red wavelength band, the transflective LCD device adopts a half wave plate (λ/2) and changes the optic axes of the polarizers and the retardation film.

Claims

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

first and second substrates facing and spaced apart from each other;

a first polarizer formed under the first substrate;

a retardation film and a second polarizer that are formed in series on the second substrate;

a backlight device being adjacent to the first polarizer;

a common electrode on a surface of the second substrate facing the first substrate;

a pixel electrode formed on the first substrate and corresponding to each pixel, the pixel electrode is divided into a transmissive portion and a reflective portion;

a liquid crystal layer interposed between the first and second substrates, wherein a thickness of the liquid crystal layer between the common electrode and the transmissive portion of the pixel electrode is more than 1.5 and less than 2.5 times larger than a thickness of the liquid crystal layer between the common electrode and the reflective portion of the pixel electrode; and

wherein a slow axis of the retardation film is disposed at an angle “

θ

”

from a transmissive axis of the second polarizer; and

wherein a transmissive axis of the first polarizer is disposed at the angle “

2θ

”

from the transmissive axis of the second polarizer.

2. The transflective LCD device according to claim 1, further comprising alignment layers formed between the liquid crystal layer and the first and second substrates.

3. The transflective LCD device according to claim 1, wherein the common electrode is transparent.

4. The transflective LCD device according to claim 1, wherein molecules of the liquid crystal layer are arranged in a horizontal direction when a voltage is not applied to the common and pixel electrodes.

5. The transflective LCD device according to claim 4, wherein an orientation direction of the liquid crystal layer is disposed at an angle “

2θ

+45°

”

from the transmissive axis of the second polarizer.

6. The transflective LCD device according to claim 4, wherein an optical retardation of the liquid crystal layer between the common electrode and the transmissive portion of the pixel electrode ranges from 250 nm to 300 nm.

7. The transflective LCD device according to claim 4, wherein an optical retardation of the liquid crystal layer between the common electrode and the reflective portion of the pixel electrode ranges from 110 nm to 160 nm.

8. The transflective LCD device according to claim 1, wherein molecules of the liquid crystal layer are arranged in a vertical direction when a voltage is not applied to the common and pixel electrodes.

9. The transflective LCD device according to claim 8, wherein the molecules of the liquid crystal layer are arranged in a horizontal direction when the voltage is applied to the common and pixel electrodes.

10. The transflective LCD device according to claim 8, wherein an orientation direction of the liquid crystal layer is disposed at an angle “

2θ

+45°

”

from the transmissive axis of the second polarizer.

11. The transflective LCD device according to claim 8, wherein an optical retardation of the liquid crystal layer between the common electrode and the transmissive portion of the pixel electrode ranges from 250 nm to 300 nm.

12. The transflective LCD device according to claim 8, wherein an optical retardation of the liquid crystal layer between the common electrode and the reflective portion of the pixel electrode ranges from 110 nm to 160 nm.

13. The transflective LCD device according to claim 1, wherein an optical retardation of the retardation film ranges from 250 nm to 300 nm.

14. The transflective LCD device according to claim 1, wherein the angle “

θ

”

ranges from 10°

to 15°

.

15. The transmissive LCD device, comprising:

first and second substrates facing and spaced apart from each other;

a first polarizer formed under the first substrate;

a retardation film and a second polarizer that are formed in series on the second substrate;

a backlight device being adjacent to the first polarizer;

a liquid crystal layer interposed between the first and second substrates;

a common electrode on a surface of the second substrate facing the first substrate, the common electrode is formed of transparent conductive material;

wherein a slow axis of the retardation film is disposed at an angle “

θ

”

from a transmissive axis of the second polarizer; and

wherein a transmissive axis of the first polarizer is disposed at the angle “

2θ

”

from the transmissive axis of the second polarizer.

16. The transmissive LCD device according to claim 15, further comprising alignment layers formed between the liquid crystal layer and the first and second substrates.

17. The transmissive LCD device according to claim 15, wherein molecules of the liquid crystal layer are arranged in a horizontal direction when a voltage is not applied to the common and pixel electrodes.

18. The transmissive LCD device according to claim 17, wherein an orientation direction of the liquid crystal layer is disposed at an angle “

2θ

+45°

”

from the transmissive axis of the second polarizer.

19. The transmissive LCD device according to claim 17, wherein an optical retardation of the liquid crystal layer between the common electrode and the pixel electrode ranges from 250 nm to 300 nm.

20. The transmissive LCD device according to claim 15, wherein molecules of the liquid crystal layer are arranged in a vertical direction when a voltage is not applied to the common and pixel electrodes.

21. The transmissive LCD device according to claim 20, wherein the molecules of the liquid crystal layer are arranged in a horizontal direction when the voltage is applied to the common and pixel electrodes.

22. The transmissive LCD device according to claim 20, wherein an orientation direction of the liquid crystal layer is disposed at an angle “

2θ

+45°

”

from the transmissive axis of the second polarizer.

23. The transmissive LCD device according to claim 20, wherein an optical retardation of the liquid crystal layer between the common electrode and the pixel electrode ranges from 250 nm to 300 nm.

24. The transmissive LCD device according to claim 15, wherein an optical retardation of the retardation film ranges from 250 nm to 300 nm.

25. The transmissive LCD device according to claim 15, wherein the angle “

θ

”

ranges from 10°

to 17.5°

.

26. The reflective LCD device, comprising:

first and second substrates facing and spaced apart from each other;

a retardation film and a polarizer that are formed in series on the second substrate;

a liquid crystal layer interposed between the first and second substrates;

a common electrode on a surface of the second substrate facing the first substrate, the common electrode is formed of a transparent conductive material;

a pixel electrode formed on the first substrate and corresponding to each pixel, the pixel electrode is formed of a conductive material; and

wherein a slow axis of the retardation film is disposed at an angle “

θ

”

from a transmissive axis of the polarizer.

27. The reflective LCD device according to claim 26, further comprising alignment layers formed between the liquid crystal layer and the first and second substrates.

28. The reflective LCD device according to claim 26, wherein molecules of the liquid crystal layer are arranged in a horizontal direction when a voltage is not applied to the common and pixel electrodes.

29. The reflective LCD device according to claim 28, wherein an orientation direction of the liquid crystal layer is disposed at an angle “

2θ

+45°

”

from the transmissive axis of the polarizer.

30. The reflective LCD device according to claim 28, wherein an optical retardation of the liquid crystal layer between the common electrode and the pixel electrode ranges from 110 nm to 160 nm.

31. The reflective LCD device according to claim 26, wherein molecules of the liquid crystal layer are arranged in a vertical direction when a voltage is not applied to the common and pixel electrodes.

32. The reflective LCD device according to claim 31, wherein the molecules of the liquid crystal layer are arranged in a horizontal direction when the voltage is applied to the common and pixel electrodes.

33. The reflective LCD device according to claim 31, wherein an orientation direction of the liquid crystal layer is disposed at an angle “

2θ

+45°

”

from the transmissive axis of the polarizer.

34. The reflective LCD device according to claim 31, wherein an optical retardation of the liquid crystal layer between the common electrode and the pixel electrode ranges from 10 nm to 160 nm.

35. The reflective LCD device according to claim 26, wherein an optical retardation of the retardation film ranges from 250 nm to 300 nm.

36. The reflective LCD device according to claim 26, wherein the angle “

θ

”

ranges from 10°

to 15°

.