Liquid crystal display device having a chiral additive and angularly displaced polarizers

• US 4,664,482 A
• Filed: 03/12/1986
• Issued: 05/12/1987
• Est. Priority Date: 03/15/1985
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Hasegawa, Shinji, Kando, Yasuhiko, Nakagomi, Tamihito
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Gallivan, Richard F.
• Application Number:
  US06/838,712
• Time in Patent Office: 426 Days
• Field of Search: 350/337, 350/346, 350/347 E, 350/341
• US Class Current: 349/101
• CPC Class Codes: G02F 1/1397 the twist being substantially higher than 90°, e.g. STN-, SBE-, OMI-LC cells

Abstract

A liquid crystal display device wherein a nematic liquid crystal having a positive dielectric anisotropy and added with a chiral material is sealed between a pair of upper and lower substrates so as to constitute a helical structure twisted within a range between 200° and 260° along a direction of thickness thereof, and polarizing axes or absorption axes of a pair of polarizing plates disposed on the upper and lower substrates are angularly displaced by a predetermined angle or predetermined angles from major axes of liquid crystal molecules adjacent to the upper and lower substrates, respectively.

Claims

1. A liquid crystal display device wherein a nematic liquid crystal having a positive dielectric anisotropy and added with a chiral material is sealed between a pair of upper and lower substrates with electrodes thereon and orienting layers formed on the electrodes and exposed surfaces thereof so as to constitute a helical structure twisted within a range between 200°

and 260°

along a direction of thickness thereof, and polarizing axes or absorption axes of a pair of polarizing plates disposed on said upper and lower substrates are angularly displaced by a predetermined angle or predetermined angels from major axes of liquid crystal molecules adjacent to said upper and lower substrates, respectively.

2. A device according to claim 1, wherein said absorption axis or said polarizing axis of each of said polarizing plates and a direction of a corresponding one of said major axes of the liquid crystal molecules adjacent to said upper and lower substrates constitute an included angle falling within a range between 20°

and 70°

.

3. A device according to claim 1, wherein a product Δ

n·

d of a thickness d (μ

m) of a liquid crystal layer and its optical anisotropy Δ

n falls within a range from 0.7 μ

m to 1.2 μ

m.

4. A device according to claim 1, wherein said orienting layers are formed by rubbing surfaces coated by polyimide resin of electrodes and exposed surfaces.

5. A liquid crystal display device wherein a nematic liquid crystal having a positive dielectric anisotropy and added with a chiral material is sealed between a pair of upper and lower substrates with electrodes thereon and orienting layers formed on the electrodes and exposed surfaces thereof so as to constitute a helical structure twisted within a range between 200°

and 260°

along a direction of thickness thereof, polarizing axes or absorption axes of a pair of polarizing plates disposed on said upper and lower substrates are angularly displaced by an angle between 20° and

70°

from major axes of liquid crystal molecules adjacent to said upper and lower substrates, respectively, and a product Δ

n·

d of a thickness d (μ

m) and an optical anisotropy Δ

n of a liquid crystal layer falls within a range from 0.7 μ

m to 1.2 μ

m.

6. A device according to claim 5, wherein said orienting layers are formed by rubbing surfaces coated by polyimide resin of electrodes and exposed surfaces.