Liquid crystal display device

• US 20060092356A1
• Filed: 10/04/2005
• Published: 05/04/2006
• Est. Priority Date: 10/29/2004
• Status: Abandoned Application

• Current Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Morimoto, Masateru, Ochiai, Takahiro, Imayama, Hirotaka, Itou, Oasamu
• Application Number:
  US11/242,042
• Publication Number:
  US 20060092356A1
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133541 Circular polarisers
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/1396 the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell G02F1/141 takes precedence
• CPC Class Codes: G02F 1/1398 the twist being below 90°
• CPC Class Codes: G02F 2413/04 Number of plates greater than or equal to 4

Abstract

The present invention provides a transmission-type, partial-transmission-type or a semi-transmission-reflection-type lateral electric field driving liquid crystal display device which can obtain the favorable transmissivity even when a circulatory polarized light is incident on a liquid crystal layer from a back surface side. In a liquid crystal display device which includes a first substrate which has a pixel electrode and a counter electrode, a second substrate which is arranged to face the first substrate in an opposed manner, a liquid crystal layer which is sandwiched between the first substrate and the second substrate, an upper polarizer which is arranged at a front surface side than the liquid crystal layer, and a lower polarizer which is arranged at a back surface side than the liquid crystal layer, the liquid crystal display device further includes a lower phase difference film which is arranged between the liquid crystal layer and the lower polarizer and converts a linearly polarized light to a circularly polarized light and an upper phase difference film which is arranged between the liquid crystal layer and the upper polarizer, the liquid crystal layer is driven by an electric field which is generated between the pixel electrode of the first substrate and the counter electrode of the first substrate, and a twist angle of the liquid crystal layer is within a range of 50° to 120° to perform a black display when a voltage is not applied.

Claims

1. A liquid crystal display device comprising:

a first substrate which has a pixel electrode and a counter electrode;

a second substrate which is arranged to face the first substrate in an opposed manner;

a liquid crystal layer which is sandwiched between the first substrate and the second substrate;

an upper polarizer which is arranged at a front surface side than the liquid crystal layer; and

a lower polarizer which is arranged at a back surface side than the liquid crystal layer, wherein

the liquid crystal display device further includes a lower phase difference film which is arranged between the liquid crystal layer and the lower polarizer and converts a linearly polarized light to a circularly polarized light and an upper phase difference film which is arranged between the liquid crystal layer and the upper polarizer,

the liquid crystal layer is driven by an electric field which is generated between the pixel electrode of the first substrate and the counter electrode of the first substrate, and

a twist angle of the liquid crystal layer is within a range of 50°

to 120°

to perform a black display when a voltage is not applied.

2. A liquid crystal display device according to claim 1, wherein the twist angle of the liquid crystal layer is set to a value which falls within a range of 60°

to 80°

when the voltage is not applied.

3. A liquid crystal display device according to claim 1, wherein the liquid crystal display device includes a reflection region which performs a display by reflecting light which is incident from the front surface side and a transmission region which performs a display by allowing light which is incident from the back surface side to pass therethrough.

4. A liquid crystal display device according to claim 3, wherein the reflection region includes a reflection layer which reflects the light which is incident from the front surface side in place between the lower phase difference film and the liquid crystal layer.

5. A liquid crystal display device according to claim 3, wherein a layer thickness of the liquid crystal layer in the reflection region and a layer thickness of the liquid crystal layer in the transmission region are substantially equal.

6. A liquid crystal display device according to claim 1, wherein a semi-transmission-reflection film which is semitransparent and has both of a transmission characteristic and a reflection characteristic is arranged in place between the lower phase difference film and the liquid crystal layer.

7. A liquid crystal display device according to claim 1, wherein the liquid crystal display device is capable of performing a reflection display in which a display is performed by reflecting light which is incident from the front surface side and a transmission display in which a display is performed by allowing light which is incident from the back surface side to pass through, and a relationship 0.75 dt≦

dr≦

1.1 dt is established when a layer thickness of the liquid crystal layer at a place where the reflection display is performed is set as dr and a layer thickness of the liquid crystal layer at a place where the transmission display is performed is set as dt.

8. A liquid crystal display device according to claim 7, wherein a relationship 0.9 dt≦

dr≦

1.1 dt is established.

9. A liquid crystal display device according to claim 7, wherein the place where the reflection display is performed and the place where the transmission display is performed are arranged at places different from each other in a plan view.

10. A liquid crystal display device according to claim 7, wherein the place where the reflection display is performed and the place where the transmission display is performed have at least one portion thereof overlapped to each other in a plan view.

11. A liquid crystal display device according to claim 1, wherein the liquid crystal display device includes a backlight which is arrange data back surface side than the lower polarizer.