Liquid crystal display apparatus

• US 7,088,409 B2
• Filed: 05/23/2005
• Issued: 08/08/2006
• 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:
  US11/135,828
• Publication Number:
  US 20050264731A1
• Time in Patent Office: 442 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 constructed by a first substrate, a second substrate, and a liquid crystal layer, said liquid crystal layer being sandwiched between said first substrate and said second substrate, said second substrate having a pixel electrode and a common electrode, an electric field substantially parallel with surfaces of said substrates being applied between said pixel electrode and said common electrode to drive said liquid crystal layer, a reflective display unit and a transmissive display unit being formed in one pixel, a first polarization film and a second polarization film being arranged outside of the first substrate and the second substrate, transmissive axes of said first polarization film and said second polarization film perpendicularly crossing each other, and either one of said transmissive axes of said first polarization film and said second polarization film being parallel with a liquid crystal alignment direction,

wherein said display has a retardation film in a portion corresponding only to said reflective display unit, said retardation film is arranged between said first polarization film and said liquid crystal layer, a retardation of the liquid crystal layer of said reflective display unit is equal to a quarter wave, and a retardation of said retardation film is equal to a half wave.

2. A display according to claim 1, wherein said liquid crystal layer has a homogeneous alignment, the transmissive axis of said first polarization film is parallel with said liquid crystal alignment direction, and an angle between a slow axis azimuth of said retardation film and the transmissive axis of said 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.

3. A display according to claim 1, wherein said retardation film is formed on the side of said first substrate near the liquid crystal layer.

4. A display according to claim 3, wherein a bireflingence of said retardation film is equal to or more than 2 times of that of said liquid crystal layer.

5. A display according to claim 4, wherein the bireflingence of said retardation film is equal to 2 times of that of said liquid crystal layer.

6. A display according to claim 1, wherein said retardation film is distributed in a part of an opaque portion of said liquid crystal display in addition to said reflective display unit.

7. A display according to claim 1, wherein said retardation film is distributed in an opaque portion of said liquid crystal display and is not come into contact with a boundary between a transparent portion and said opaque portion.