Liquid crystal display device

• US 20010043297A1
• Filed: 06/25/2001
• Published: 11/22/2001
• Est. Priority Date: 01/21/2000
• Status: Active Grant

• Current Assignee: Citizen Holdings Co., Ltd. (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Arai, Makoto
• Granted Patent: US 6,717,641 B2
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 2203/02 reflective
• CPC Class Codes: G02F 2203/09 transflective

Abstract

A TN liquid crystal cell constituted by sandwiching a nematic liquid crystal which is aligned at a twist angle of about 90° between a first and a second transparent substrate each of which has transparent electrodes is used, an absorption-type polarizing film is provided on the outside, which is the visible side, of the second substrate, and a reflection-type polarizing film, a scattering layer, and a mirror reflector are provided in order on the outside, which is the opposite side to the visible side of the TN liquid crystal cell, of the first substrate, thereby constituting a liquid crystal display device for performing a reflection display of information of character and image in an achromatic metallic tone within a bright diffused white background.

Claims

1. A liquid crystal display device comprising:

a TN liquid crystal cell constituted by sandwiching a nematic liquid crystal which is aligned at a twist angle of about 90°

between a first and a second transparent substrate each having transparent electrodes;

an absorption-type polarizing film provided on the outside, which is the visible side of said TN liquid crystal cell, of said second substrate;

a reflection-type polarizing film provided on the outside, which is the opposite side to the visible side of said TN liquid crystal cell, of said first substrate;

a scattering layer provided on the outside of said reflection-type polarizing film; and

a mirror reflector provided on the outside of said scattering layer.

2. A liquid crystal display device according to

claim 1

,

wherein said mirror reflector is a mirror transflective reflector, and a backlight is provided on the outside of said mirror transflective reflector.

3. A liquid crystal display device comprising:

an STN liquid crystal cell constituted by sandwiching a nematic liquid crystal which is aligned at a twist angle from 180°

to 270°

between a first and a second transparent substrate each having transparent electrodes;

an absorption-type polarizing film provided on the outside, which is the visible side of said STN liquid crystal cell, of said second substrate;

a retardation film provided between said absorption-type polarizing film and said second substrate;

a reflection-type polarizing film provided on the outside, which is the opposite side to the visible side of said STN liquid crystal cell, of said first substrate;

a scattering layer provided on the outside of said reflection-type polarizing film; and

a mirror reflector provided on the outside of said scattering layer.

4. A liquid crystal display device according to

claim 3

,

wherein said mirror reflector is a mirror transflective reflector, and a backlight is provided on the outside of said mirror transflective reflector.

5. A liquid crystal display device according to

claim 3

,

wherein said retardation film satisfies conditions of:

nx>

nz>

ny

where nx is a refractive index in a stretching direction of said retardation film, ny is a refractive index in a planar direction orthogonal to the stretching direction, and nz is a refractive index in a thickness direction.

6. A liquid crystal display device according to

claim 4

,

wherein said retardation film satisfies conditions of:

nx>

nz>

ny

where nx is a refractive index in a stretching direction of said retardation film, ny is a refractive index in a planar direction orthogonal to the stretching direction, and nz is a refractive index in a thickness direction.

7. A liquid crystal display device according to

claim 3

,

wherein said retardation film is a twisted retardation film, and a difference between an amount of birefringence of said STN liquid crystal cell and a retardation value of said twisted retardation film ranges from 0.15 μ

m to 0.25 μ

m.

8. A liquid crystal display device according to

claim 4

,

wherein said retardation film is a twisted retardation film, and a difference between an amount of birefringence of said STN liquid crystal cell and a retardation value of said twisted retardation film ranges from 0.15 μ

m to 0.25 μ

m.

9. A liquid crystal display device according to

claim 3

,

wherein said retardation film is a twisted retardation film, and a value of Δ

T=|Ts|−

|Tc| ranges from 0°

to 30°

where Δ

T is a difference between an absolute value of a twist angle Ts of said STN liquid crystal cell and an absolute value of a twist angle Tc of said twisted retardation film.

10. A liquid crystal display device according to

claim 4

,

wherein said retardation film is a twisted retardation film, and a value of Δ

T=|Ts|−

|Tc| ranges from 0°

to 30°

where Δ

T is a difference between an absolute value of a twist angle Ts of said STN liquid crystal cell and an absolute value of a twist angle Tc of said twisted retardation film.