Liquid crystal device and electronic apparatus

• US 20080204640A1
• Filed: 10/30/2007
• Published: 08/28/2008
• Est. Priority Date: 02/22/2007
• Status: Active Grant

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Epson Imaging Devices Corporation (Seiko Group)
• Inventors: Wada, Hiroshi
• Granted Patent: US 8,355,101 B2
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133784 by rubbing
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]

Abstract

A liquid crystal device includes a first substrate and a second substrate facing each other, a liquid crystal layer disposed between the first substrate and the second substrate, an aligning film which is disposed on a liquid crystal layer side surface of the second substrate and on which a rubbing processing is performed, a plurality of sub-pixels arranged in planar regions of the first substrate and the second substrate, a first electrode and a second electrode which are disposed on a liquid crystal layer side surface of the first substrate and which generate an electric field therebetween, in which the second electrode includes a plurality of electrode line-shaped portions arranged in parallel to each other and spaced apart from each other, each sub-pixel includes a reflective display region in which a light reflective film is disposed and a transmissive display region in which a light reflective film is not disposed, wherein a layer thickness adjusting film, which allows the liquid crystal layer to have different layer thicknesses in the reflective display region and in the transmissive display region, is disposed between the second substrate and the aligning film, the layer thickness adjusting film has a step portion with a step plane extending in a thickness direction of the layer thickness adjusting film near a boundary portion between the reflective display region and the transmissive display region, when an angle between a direction in which a rubbing processing is performed and an extending direction of the step plane is defined as α, 0°≦α≦20°, and ends of liquid crystal molecules, which are on a leading side of rubbing, are arranged so as to direct toward the step plane when a voltage is applied across the first electrode and the second electrode.

Claims

1. A liquid crystal device, comprising:

a first substrate and a second substrate facing each other;

a liquid crystal layer disposed between the first substrate and the second substrate;

an aligning film which is disposed on a liquid crystal layer side surface of the second substrate and on which a rubbing processing is performed; and

a plurality of sub-pixels arranged in planar regions of the first substrate and the second substrate;

a first electrode and a second electrode which are disposed on a liquid crystal layer side surface of the first substrate and which generate an electric field therebetween,

wherein the second electrode includes a plurality of electrode line-shaped portions arranged in parallel to each other and spaced apart from each other, wherein each sub-pixel includes a reflective display region in which a light reflective film is disposed and a transmissive display region in which a light reflective film is not disposed, wherein a layer thickness adjusting film, which allows the liquid crystal layer to have different layer thicknesses in the reflective display region and in the transmissive display region, is disposed between the second substrate and the aligning film, wherein the layer thickness adjusting film has a step portion with a step plane extending in a thickness direction of the layer thickness adjusting film near a boundary portion between the reflective display region and the transmissive display region, wherein when an angle between a direction in which a rubbing processing is performed and an extending direction of the step plane is defined as a, 0°

≦

α

≦

20°

, and wherein ends of liquid crystal molecules, which are on a leading side of rubbing, are arranged so as to direct toward the step plane when a voltage is applied across the first electrode and the second electrode.

2. The liquid crystal display according to claim 1, wherein liquid crystals have a positive dielectric anisotropy, wherein the transmissive display region and the reflective display region are arranged in a longitudinal direction of each sub-pixel, and wherein the extending direction of the electrode line-shaped portions has an angle to a lateral direction of the sub-pixels in a plan view viewed in a direction from a liquid crystal layer side, in which the angle is in a range from 0°

to 45°

in clockwise direction or in a range from 0°

to 45°

in counter-clockwise direction.

3. The liquid crystal device according to claim 1, wherein when an angle between a rubbing direction and the extending direction of the electrode line-shaped portion is defined as β

, 5°

≦

β

≦

20°

, wherein when the angle between the rubbing direction and an extending direction of the step plane is defined as α

, α

≠

0°

, and wherein the rubbing processing is performed in a direction approaching the step plane from an opposite side of the step plane.

4. The liquid crystal device according to claim 3, wherein the electrode line-shaped portions and the step plane extend in a direction parallel to a lateral direction of the sub-pixels.

5. The liquid crystal device according to claim 4, wherein the step plane and the electrode line-shaped portion are parallel to each other.

6. The liquid crystal display according to claim 1, wherein an angle between the rubbing direction and the extending direction of the electrode line-shaped portion is defined as β

, 5°

≦

β

≦

20°

, and wherein when an angle between the rubbing direction and the extending direction of the step plane is defined as α

, α

=0°

.

7. The liquid crystal device according to claim 6, wherein when an angle between the electrode line-shaped portion and the lateral direction of the sub-pixel is defined as δ

, δ

=0°

, wherein when an angle between the extending direction of the electrode line-shaped portion and the extending direction of the step plane is defined as ∈

, 5°

≦

∈

≦

20°

, and wherein the angle α

between the rubbing direction and the extending direction of the step plane is 0°

.

8. The liquid crystal device according to claim 6, wherein when an angle between the electrode line-shaped portion and the lateral direction of the sub-pixel is defined as δ

, 5°

≦

δ

≦

20°

, wherein when an angle between the electrode-line shaped portion and the extending direction of the step plane is defined as ∈

, 5°

≦

∈

≦

20°

, and wherein the angle α

between the rubbing direction and the extending direction of the step plane is 0°

.

9. The liquid crystal device according to claim 6, wherein the second electrode includes two domains in which inclined directions of the electrode line-shaped portions in different domains are different from each other, in which the electrode line-shaped portions have an angle in clockwise direction to the lateral direction of the sub-pixel in a plan view viewed in a direction from a liquid crystal layer side in either one domain of the two domains, and the electrode line-shaped portions have an angle in counter-clockwise direction to the lateral direction of the sub-pixel in a plan viewed in a direction from the liquid crystal layer side in the other domain of the two domains, wherein an angle δ

between the electrode line-shaped portion and the lateral direction of the sub-pixel is in a range expressed by 5°

≦

δ

≦

20°

, wherein an angle ∈

between an extending direction of the electrode line-shaped portion and an extending direction of the step plane is in a range expressed by 5°

≦

∈

≦

20°

, and wherein the angle α

between the rubbing direction and the extending direction of the step plane is 0°

.

10. The liquid crystal device according to claim 6, wherein one pixel includes sub-pixels having colored films of different colors, which are arranged in the lateral direction of the sub-pixel, wherein the layer thickness adjusting film is formed so as to have a shape corresponding to each pixel, wherein an angle δ

between the electrode line-shaped portion and the lateral direction of the sub-pixel is in a ranged expressed by 5°

≦

δ

≦

20°

, wherein an angle ∈

between an extending direction of the electrode line-shaped portion and an extending direction of the step plane is in a range expressed by 5°

≦

∈

≦

20°

, wherein the angle α

between the rubbing direction and an extending direction of the step plane is 0°

, and wherein the step plane extends in a straight line form in one pixel.

11. The liquid crystal device according to claim 1, wherein the step plane is an inclined plane where a layer thickness of the layer thickness adjusting film continuously changes.

12. The liquid crystal device according to claim 1, wherein the first electrode is a plane-shaped electrode having a portion overlapping the electrode line-shaped portion of the second electrode.

13. The liquid crystal device according to claim 1, wherein the layer thickness adjusting film is disposed in a band form over a plurality of sub-pixels.

14. The liquid crystal device according to claim 1, wherein layer thickness adjusting film is formed including a phase shifting film, and a retardation value Δ

nd of the phase shifting film is a half wavelength.

17. An electronic apparatus having the liquid crystal device according to claim 1.

15. A liquid crystal device, comprising:

a first substrate and a second substrate facing each other;

a liquid crystal layer disposed between the first substrate and the second substrate;

an aligning film which is disposed on a liquid crystal layer side surface of the second substrate and on which a rubbing processing is performed;

a plurality of sub-pixels arranged in planar regions of the first substrate and the second substrate; and

a first electrode and a second electrode disposed on a liquid crystal layer side surface of the first substrate and which generates an electric field therebetween;

wherein the second electrode includes a plurality of electrode line-shaped portions arranged in parallel to each other and spaced apart from each other, wherein each sub-pixel includes a reflective display region in which a light reflective film is disposed and a transmissive display region in which a light reflective film is not disposed, wherein a layer thickness adjusting film which intends to make the liquid crystal layer have different layer thicknesses in the reflective display region and the transmissive display layer is disposed between the second substrate and the aligning film, wherein the layer thickness adjusting film includes a step portion having a step plane extending in a thickness direction of the layer thickness adjusting film near a boundary portion of the reflective display region and the transmissive display region, wherein when an angle between the rubbing direction and an extending direction of the step plane is defined as α

, 0°

≦

α

≦

20°

, and wherein the step plane is disposed at a position where ends of liquid crystal molecules, which are disposed on a leading side in a rubbing direction and move when a voltage is applied across the first electrode and the second electrode in the transmissive display region, abut against.

16. A liquid crystal device, comprising:

a first substrate and a second substrate facing each other;

a liquid crystal layer disposed between the first substrate and the second substrate;

an aligning film on which a rubbing processing is performed and which is disposed on a liquid crystal layer side surface of the second substrate;

a plurality of sub-pixels arranged in planar regions of the first substrate and the second substrate,

a first electrode and a second electrode disposed on a liquid crystal side surface of the first substrate and which generates an electric field therebetween,

wherein the second electrode has a plurality of electro line-shaped portions arranged in parallel with each other and spaced apart from each other, wherein each sub-pixel includes a reflective display region in which a light reflective film is disposed and a transmissive display region in which the light reflective film is not disposed, wherein a layer thickness adjusting film is disposed between the second substrate and the aligning film in order to make the liquid crystal layer have different layer thicknesses in the reflective display region and in the transmissive display region different, wherein the layer thickness adjusting film has a step portion having a step plane extending in a layer thickness direction of the layer thickness adjusting film near a boundary portion of the reflective display region and the transmissive display region, wherein liquid crystal molecules in the liquid crystal layer are initially aligned at a pre-tilt angle to a surface of the aligning film, and wherein the step plane is arranged at a position where ends of the liquid crystal molecules, which are separated from the surface of the aligning film, of both ends of the liquid crystal molecules aligned at the pre-tilt angle when an electric field is generated between the first electrode and the second electrode, move in the transmissive display region.