Liquid crystal display

• US 7,630,036 B2
• Filed: 11/17/2006
• Issued: 12/08/2009
• Est. Priority Date: 11/18/2005
• 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: Oka, Shinichiro, Komura, Shinichi, Adachi, Masaya
• Primary Examiner(s): STAHL, MICHAEL J
• Application Number:
  US11/600,858
• Publication Number:
  US 20070115409A1
• Time in Patent Office: 1,117 Days
• Field of Search: None
• US Class Current: 349/114
• 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 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/134318 having a patterned common electrode
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• 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
• CPC Class Codes: G02F 2201/40 Arrangements for improving the aperture ratio

Abstract

A liquid crystal display having a plurality of pixels includes a liquid crystal layer disposed between first and second substrates, and first and second polarization plates disposed on the side opposite to the side where the liquid crystal layer is disposed with respect to the first and second substrates. The second substrate includes a pixel electrode on the side of the liquid crystal layer. Each of the plurality of pixels includes a reflection area and a transmission area. A ratio of the common electrode occupying the aperture in the reflection area is smaller than a ratio of the common electrode occupying the aperture of the transmission area.

Claims

1. A liquid crystal display including a plurality of pixels, comprising:

a first substrate;

a second substrate;

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

a first polarization plate disposed on the side opposite to the side where the liquid crystal layer is disposed with respect to the first substrate; and

a second polarization plate disposed on the side opposite to the side where the liquid crystal layer is disposed with respect to the second substrate;

wherein the second substrate includes a pixel electrode on the side of the liquid crystal layer;

wherein the first substrate includes a common electrode on the side of the liquid crystal layer;

wherein each of the plurality of pixels includes a reflection area and a transmission area;

wherein a ratio of the common electrode occupying the aperture in the reflection area is smaller than a ratio of the common electrode occupying the aperture of the transmission area;

wherein a ratio of the pixel electrode occupying the aperture in the reflection area is smaller than a ratio of the pixel electrode occupying the aperture of the transmission area; and

wherein the ratio of the common electrode and the pixel electrode occupying the aperture in the transmission area is 100%.

2. A liquid crystal display according to claim 1, wherein the liquid crystal layer includes liquid crystal molecules having the major axes which are aligned substantially vertically to the first and second substrates when voltage is not applied.

3. A liquid crystal display according to claim 1, wherein the liquid crystal layer includes liquid crystal molecules having the major axes which are aligned substantially horizontally to the first and second substrates when voltage is not applied, and

a pre-tilt angle of the liquid crystal layer is equal to or larger than 0 degree and smaller than 10 degrees, and

a twist angle of the liquid crystal molecules between the first and second substrates being equal to or larger than 0 degree and smaller than 90 degrees.

4. A liquid crystal display according to claim 1, further comprising signal lines and scanning lines disposed on the second substrate and thin film transistors disposed at places where the signal lines and the scanning lines intersect each other.

5. A liquid crystal display according to claim 1, further comprising a color filter disposed on the side where the liquid crystal layer is disposed with respect to the first substrate.

6. A liquid crystal display according to claim 1, wherein the first substrate or the second substrate or both of them are comprised of one of glass, plastic, and polyether sulphone.

7. A liquid crystal display according to claim 1, further comprising one or more retardation films disposed between the first substrate and the first polarization plate and between the second substrate and the second polarization plate.

8. A liquid crystal display according to claim 7, wherein the retardation films have a phase difference of ¼

wavelength.

9. A liquid crystal display according to claim 7, wherein the retardation films includes a first retardation film having a phase difference of ¼

wavelength and a second retardation film having ½

wavelength, and

the first retardation film is disposed between the liquid crystal layer and the second retardation film,

the second retardation film being disposed between the first polarization plate or the second polarization plate and the first retardation film.

10. A liquid crystal display according to claim 7, wherein the retardation films include a negative C-plate.

11. A liquid crystal display according to claim 1, further comprising a reflecting plate disposed in the reflection area and

an insulating layer disposed between the common electrode or the pixel electrode and the reflecting plate.

12. A liquid crystal display according to claim 11, wherein the reflecting plate is made of nonconductive material.

13. A liquid crystal display according to claim 1, wherein at least one of the pixel electrode and the common electrode in the reflection area comprises an inter-digital electrode.

14. A liquid crystal display according to claim 1, wherein at least one of the pixel electrode and the common electrode in the reflection area comprises an inter-digital electrode, and

comprising one or more slits disposed substantially parallel to the longitudinal direction of the inter-digital electrode.

15. A liquid crystal display according to claim 1,

wherein the ratio of the common electrode and the pixel electrode occupying the aperture in the reflection area is equal to or larger than 40% and smaller than 60%.

16. A liquid crystal display according to claim 6, wherein at least one of a plastic and a polyether sulphone substrate is covered with a surface comprising silicon nitride.