Transflective liquid crystal display device

• US 7,834,964 B2
• Filed: 06/29/2007
• Issued: 11/16/2010
• Est. Priority Date: 07/14/2006
• Status: Expired due to Fees

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Morimoto, Masateru, Sasaki, Tohru, Ochiai, Takahiro, Miyazawa, Toshio, Maki, Masahiro
• Primary Examiner(s): Healy; Brian M.
• Assistant Examiner(s): Anderson; Guy G
• Application Number:
  US11/819,907
• Publication Number:
  US 20080013023A1
• Time in Patent Office: 1,236 Days
• Field of Search: 349113-114, 349/141, 349/110, 349/143
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/1337 Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]

Abstract

A transflective liquid crystal display device with improved display quality in which the liquid initial alignment direction of the liquid crystal layer is in a direction perpendicular to the extending direction of a clearance between the counter electrode of a transmission portion and a counter electrode of a reflection portion or in a direction within a range of ±2° in the clockwise direction perpendicular to the extending direction of the clearance in a case where the liquid crystal layer comprises positive type liquid crystals, or the liquid crystal initial alignment direction of the liquid crystal layer is in a direction parallel with the extending direction of a clearance, or a direction within a range of ±2° in the clockwise direction relative to the extending direction of the clearance in a case where the liquid crystal layer comprises negative type liquid crystals.

Claims

1. A transflective liquid crystal display device including a liquid crystal display panel having a pair of substrates and a liquid crystal layer put between the pair of substrates, in which the liquid crystal display panel has a plurality of sub-pixels each having a transmission portion and a reflection portion, and each of the plurality of sub-pixels has a pixel electrode and a counter electrode, wherein:

in each of the sub-pixels, the pixel electrode is in common with the transmission portion and the reflection portion, the counter electrode is independent between the transmission portion and the reflection portion;

a clearance extending to separate the counter electrode of the transmission portion and the counter electrode of the reflection portion;

the potential applied to the counter electrode is different between the transmission portion and the reflection portion;

the liquid crystal layer comprises positive type liquid crystals; and

the liquid crystal initial alignment direction of the liquid crystal layer is in a direction perpendicular to an extending direction of the clearance between the counter electrode of the transmission portion and the counter electrode of the reflection portion, or in a direction within a range of ±

2°

in a clockwise direction relative to the direction perpendicular to the extending direction of the clearance.

3. A transflective liquid crystal display device according to claim 1, wherein:

the counter electrode and the pixel electrode are formed on one of the pair of substrates;

the transmission portion has a normally black characteristic providing black display in a state of not applying a voltage; and

the reflection portion has a normally white characteristic providing white display in a state of not applying a voltage.

4. A transflective liquid crystal display device according to claim 3, wherein:

the counter electrode is a planar electrode;

the pixel electrode is an electrode having a plurality of linear portions and formed to one of the substrates to a layer above the counter electrode; and

the extending direction of the clearance and the extending direction of the linear portion of the pixel electrode intersect obliquely.

5. A transflective liquid crystal display device according to claim 1, wherein:

a first polarization plate is disposed on one substrate of the pair of substrates and a second polarization plate is disposed on the other substrate of the pair of substrates respectively;

the respective polarization axes of the first and second polarization plates are perpendicular to each other; and

the liquid crystal initial alignment axis of the liquid crystal layer and the polarization axis of one of the first polarization plate and the second polarization plate are aligned.

6. A transflective liquid crystal display device according to claim 1, wherein:

in each of the sub-pixels, the potential applied to the counter electrode for one of the transmission portion and the reflection portion is a potential higher than the potential applied to the pixel electrode; and

the potential applied to the counter electrode for the other of the transmission portion or the reflection portion is a potential lower than the potential applied to the pixel electrode.

7. A transflective liquid crystal display device according to claim 1, wherein for adjacent two display lines defined as one display line and the other display line, the counter electrode of the reflection portion in each of the sub-pixels of one display line, and the counter electrode of the transmission portion in each of the sub-pixels of the other display line are a common electrode.

2. A transflective liquid crystal display device including a liquid crystal display panel having a pair of substrates and a liquid crystal layer put between the pair of substrates, in which the liquid crystal display panel has a plurality of sub-pixels each having a transmission portion and a reflection portion, and each of the plurality of sub-pixels has a pixel electrode and a counter electrode, wherein:

in each of the sub-pixels, the pixel electrode is in common with the transmission portion and the reflection portion, the counter electrode is independent between the transmission portion and the reflection portion;

a clearance extending to separate the counter electrode of the transmission portion and the counter electrode of the reflection portion;

the potential applied to the counter electrode is different between the transmission portion and the reflection portion;

the liquid crystal layer comprises negative type liquid crystals; and

the liquid crystal initial alignment direction of the liquid crystal layer is in a direction parallel to an extending direction of the clearance between the counter electrode of the transmission portion and the counter electrode of the reflection portion, or in a direction within a range of ±

2°

in a clockwise direction relative to the extending direction of the clearance.

8. A transflective liquid crystal display device according to claim 2, wherein:

the counter electrode and the pixel electrode are formed on one of the pair of substrates;

the transmission portion has a normally black characteristic providing black display in a state of not applying a voltage; and

the reflection portion has a normally white characteristic providing white display in a state of not applying a voltage.

9. A transflective liquid crystal display device according to claim 8, wherein:

the counter electrode is a planar electrode;

the pixel electrode is an electrode having a plurality of linear portions and formed to one of the substrates to a layer above the counter electrode; and

the extending direction of the clearance and the extending direction of the linear portion of the pixel electrode intersect obliquely.

10. A transflective liquid crystal display device according to claim 8, wherein:

a first polarization plate is disposed on one substrate of the pair of substrates and a second polarization plate is disposed on the other substrate of the pair of substrates respectively;

the respective polarization axes of the first and second polarization plates are perpendicular to each other; and

the liquid crystal initial alignment axis of the liquid crystal layer and the polarization axis of one of the first polarization plate and the second polarization plate are aligned.