Liquid crystal display apparatus

• US 7,688,406 B2
• Filed: 04/04/2006
• Issued: 03/30/2010
• Est. Priority Date: 05/25/2004
• 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: Tanno, Junji, Morimoto, Masateru, Ochiai, Takahiro, Itou, Osamu, Imayama, Hirotaka
• Primary Examiner(s): Dudek; James A
• Application Number:
  US11/397,087
• Publication Number:
  US 20060192912A1
• Time in Patent Office: 1,456 Days
• Field of Search: 349/114, 349/141
• 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 1/133565 inside the LC elements, i.e. between the cell substrates
• CPC Class Codes: G02F 1/133631 with a spatial distribution of the retardation value
• 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 display of a transflective IPS system in which a lateral electric field is applied to a liquid crystal layer. Polarization films are arranged on the entire surface of a transmissive display unit and a reflective display unit in a manner similar to a transmissive IPS system. An inner retardation layer whose retardation is equal to a half wave is formed in the reflective display unit. A retardation of the liquid crystal layer of the reflective display unit is set to a quarter wave. Thus, a reflective display can be performed in a wide range of environment from a light place to a dark place and a transmissive display of a wide viewing angle and high picture quality can be performed.

Claims

1. A liquid crystal display, comprising:

a first substrate;

a second substrate;

a liquid crystal layer arranged between said first and second substrates;

thin-film transistors provided at intersecting portions of a plurality of signal lines and a plurality of scanning lines;

a pixel electrode formed on the second substrate and having a slit;

a common electrode arranged between the second substrate and the pixel electrode and superposed with the pixel electrode;

a first polarization film arranged on an opposite side of a side where the liquid crystal layer of the first substrate is arranged; and

a second polarization film arranged on an opposite side of a side where the liquid crystal layer of the second substrate is arranged,

wherein the liquid crystal layer is driven by applying an electric field to the pixel electrode and the common electrode, the electric field being parallel to a surface of the first substrate and a surface of the second substrate,

wherein a reflective display unit and a transmissive display unit are provided in a pixel as a region surrounded by the signal line and the scanning line,

wherein a retardation film is arranged between the first polarization film and the liquid crystal layer and arranged only on a position corresponding to the reflective display unit,

and wherein the liquid crystal layer has a homogeneous alignment, the transmissive axis of the first polarization film is parallel to a liquid crystal alignment direction, and an angle between a slow axis azimuth of the retardation film and the transmissive axis of the first polarization film lies within a range from 20°

or more to 25°

or less or a range from 60°

or more to 75°

or less.

2. The liquid crystal display according to claim 1, wherein a transmissive axis of the first polarization film is orthogonal with that of the second polarization film.

3. The liquid crystal display according to claim 1, wherein the pixel electrode is formed in pectinate and the common electrode is formed tabularly.