Liquid crystal display device for transflector having opening in a first electrode for forming a liquid crystal domain and openings at first and second corners of the domain on a second electrode

• US 7,385,660 B2
• Filed: 12/07/2004
• Issued: 06/10/2008
• Est. Priority Date: 12/08/2003
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kume, Yasuhiro, Tamai, Kazuhiko, Onishi, Noriaki, Kurihara, Takashi, Nagae, Nobukazu
• Primary Examiner(s): Nelms; David
• Assistant Examiner(s): Heyman; John
• Application Number:
  US11/005,322
• Publication Number:
  US 20050140916A1
• Time in Patent Office: 1,281 Days
• Field of Search: 349/114, 349/119
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/133753 with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
• CPC Class Codes: G02F 1/13394 spacers regularly patterned on the cell subtrate, e.g. walls, pillars G02F1/133377 takes precedence
• CPC Class Codes: G02F 1/134318 having a patterned common electrode
• 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

The liquid crystal display device includes a first substrate 1110a, a second substrate 1110b placed to face the first substrate, and a liquid crystal layer 1120 interposed between the first substrate and the second substrate. The liquid crystal display device has a plurality of pixels each including a first electrode 1111 formed on the first substrate, a second electrode 1131 formed on the second substrate, and the liquid crystal layer interposed between the first electrode and the second electrode. The second electrode 1131 has at least one opening 1114 formed at a predetermined position in the pixel, the first substrate has a shading region in gaps between the plurality of pixels, and a wall structure 1115 is placed regularly on the surface of the first substrate facing the liquid crystal layer in the shading region. The liquid crystal layer has at least one liquid crystal domain having axisymmetric alignment formed when at least a predetermined voltage is applied, and the center axis of the axisymmetric alignment of the at least one liquid crystal domain is formed in or near the at least one opening.

Claims

1. A liquid crystal display device comprising

a first substrate, a second substrate placed to face the first substrate, and a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the liquid crystal display device has a plurality of pixels each including a first electrode formed on the first substrate, a second electrode formed on the second substrate, and the liquid crystal layer interposed between the first electrode and the second electrode,

the second electrode has at least one opening formed at a predetermined position in the pixel, the first substrate has a shading region in gaps between the plurality of pixels, and a wall structure is placed regularly on the surface of the first substrate facing the liquid crystal layer in the shading region,

the liquid crystal layer has at least one liquid crystal domain having axisymmetric alignment formed when at least a predetermined voltage is applied, and the center axis of the axisymmetric alignment of the at least one liquid crystal domain is formed in or near the at least one opening, and

wherein the second electrode comprises the at least one opening defined therein at approximately a center axis of a first one of the domains, and the first electrode has cut-out portions and/or openings defined therein at at least first and second corners of the first domain.

2. The liquid crystal display device of claim 1, wherein when a voltage giving a relative transmittance of 10% is applied across the liquid crystal layer interposed between the first electrode and the second electrode, the potential at the at least one opening in the second electrode is lower than a threshold voltage of the liquid crystal layer.

3. The liquid crystal display device of claim 1, wherein the size Wh of the at least one opening satisfies the condition 2 μ

m≦

Wh≦

20 μ

m.

4. The liquid crystal display device of claim 1, wherein a support for defining the thickness of the liquid crystal layer is formed in the shading region located in gaps between the plurality of pixels.

5. The liquid crystal display device of claim 1, wherein the first electrode includes a transparent electrode defining a transmission region and a reflective electrode defining a reflection region, and the thickness dt of the liquid crystal layer in the transmission region and the thickness dr of the liquid crystal layer in the reflection region satisfy the relationship 0.3 dt<

dr<

0.7 dt.

6. The liquid crystal display device of claim 1, wherein the first electrode includes a transparent electrode defining a transmission region and a reflective electrode defining a reflection region, the at least one liquid crystal domain includes a liquid crystal domain formed in the transmission region, and

the first electrode has a plurality of cuts formed point-symmetrically with respect to the opening.

7. The liquid crystal display device of claim 5, wherein a transparent dielectric layer is selectively formed on the second substrate in the reflection region.

8. The liquid crystal display device of claim 7, wherein the transparent dielectric layer has a function of scattering light.

9. The liquid crystal display device of claim 5, further comprising a color filter layer formed on the second substrate, wherein the optical density of the color filter layer in the reflection region is lower than that in the transmission region.

10. The liquid crystal display device of claim 1, further comprising:

a pair of polarizing plates placed to face each other via the first substrate and the second substrate; and

at least one biaxial optical anisotropic medium layer placed between the first substrate and one of the pair of polarizing plates and/or between the second substrate and the other polarizing plate.

11. The liquid crystal display device of claim 1, further comprising:

a pair of polarizing plates placed to face each other via the first substrate and the second substrate; and

at least one uniaxial optical anisotropic medium layer placed between the first substrate and one of the pair of polarizing plates and/or between the second substrate and the other polarizing plate.

12. A liquid crystal display device comprising

a first substrate, a second substrate placed to face the first substrate, and a liquid crystal layer interposed between the first substrate and the second substrate,

wherein the liquid crystal display device has a plurality of pixels each including a first electrode formed on the first substrate, a second electrode formed on the second substrate, and the liquid crystal layer interposed between the first electrode and the second electrode,

the first substrate has a shading region in gaps between the plurality of pixels, and a wall structure is placed regularly on the surface of the first substrate facing the liquid crystal layer in the shading region,

the first electrode has at least one first opening formed at a predetermined position in the pixel,

the second electrode has at least one second opening formed at a predetermined position in the pixel,

the liquid crystal layer has at least one liquid crystal domain having axisymmetric alignment formed when at least a predetermined voltage is applied, and the center axis of the axisymmetric alignment of the at least one liquid crystal domain is formed in or near at least one of the at least one first opening and the at least one second opening, and

wherein the second electrode comprises the at least one second opening defined therein at approximately a center axis of a first one of the domains, and the first electrode has cut-out portions and/or openings defined therein at at least first and second corners of the first domain.

13. The liquid crystal display device of claim 12, wherein one end of the center axis of axisymmetric alignment of the at least one liquid crystal domain is in or near the at least one first opening, and the other end is in or near the at least one second opening.

14. The liquid crystal display device of claim 12, wherein the at least one first opening and the at least one second opening are placed to at least overlap each other via the liquid crystal layer.

15. The liquid crystal display device of claim 12, wherein when a voltage giving a relative transmittance of 10% is applied across the liquid crystal layer interposed between the first electrode and the second electrode, the potential at at least one of the at least one first opening and the at least one second opening is lower than a threshold voltage of the liquid crystal layer.

16. The liquid crystal display device of claim 15, wherein when a voltage giving a relative transmittance of 10% is applied across the liquid crystal layer interposed between the first electrode and the second electrode, the potentials at the at least one first opening and the at least one second opening are lower than the threshold voltage of the liquid crystal layer.

17. The liquid crystal display device of claim 12, wherein the size Wh′

of the at least one first opening and the at least one second opening satisfies the condition 1 μ

m≦

Wh′

≦

18 μ

m.

18. The liquid crystal display device of claim 12, wherein a support for defining the thickness of the liquid crystal layer is formed in the shading region located in gaps between the plurality of pixels.

19. The liquid crystal display device of claim 12, wherein the first electrode includes a transparent electrode defining a transmission region and a reflective electrode defining a reflection region, and the thickness dt of the liquid crystal layer in the transmission region and the thickness dr of the liquid crystal layer in the reflection region satisfy the relationship 0.3 dt<

dr<

0.7 dt.

20. The liquid crystal display device of claim 12, wherein the first electrode includes a transparent electrode defining a transmission region and a reflective electrode defining a reflection region, the at least one liquid crystal domain includes a liquid crystal domain formed in the transmission region, the at least one first opening and/or the at least one second opening include an opening corresponding to the center axis of the liquid crystal domain formed in the transmission region, and

the first electrode has a plurality of cuts formed point-symmetrically with respect to the opening.

21. The liquid crystal display device of claim 19, wherein a transparent dielectric layer is selectively formed on the second substrate in the reflection region.

22. The liquid crystal display device of claim 21, wherein the transparent dielectric layer has a function of scattering light.

23. The liquid crystal display device of claim 19, further comprising a color filter layer formed on the second substrate, wherein the optical density of the color filter layer in the reflection region is lower than that in the transmission region.

24. The liquid crystal display device of claim 12, further comprising:

a pair of polarizing plates placed to face each other via the first substrate and the second substrate; and

at least one biaxial optical anisotropic medium layer placed between the first substrate and one of the pair of polarizing plates and/or between the second substrate and the other polarizing plate.

25. The liquid crystal display device of claim 12, further comprising:

a pair of polarizing plates placed to face each other via the first substrate and the second substrate; and

at least one uniaxial optical anisotropic medium layer placed between the first substrate and one of the pair of polarizing plates and/or between the second substrate and the other polarizing plate.