Optical disc memory system utilizing a smectic chiral liquid crystal

[54] OPTICAL DISC MEMORY SYSTEM

UTILIZING A SMECTIC CfflRAL LIQUID
CRYSTAL

[75] Inventor: Shunpei Yamazaki, Tokyo, Japan

[73] Assignee: Semiconductor Energy Laboratory Co., Ltd., Kanagawa, Japan

[21] Appl. No.: 874,102

[22] Filed: Jun. 13,1986

[51] Int. CI." G11B 11/14; G11C 13/04

[52] U.S. CI 369/13; 369/110;

365/108; 365/117

[58] Field of Search 350/351, 350 S, 334,

350/335, 349, 340, 341, 330; 365/108, 117; 369/13, 110, 111, 100; 360/114, 59

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OTHER PUBLICATIONS

MoL Cryst. Liq. Cryst, vol. 94, 1983, N. A. Clark et al.,
"Ferroelectric Liquid Crystal Electro-Optics Using the
Surface Stabilized Structure", pp. 213-234.
H. Birecki et al., "Erasable Optical Liquid Crystal Disc
Memory", SPIE, 420, 194 (1983).

Primary Examiner—Alan Faber

Assistant Examiner—Hoa T. Nguyen

Attorney, Agent, or Firm—Gerald J. Ferguson, Jr.

[57] ABSTRACT

An improved magneto-optical disc memory recording and reading system with a ferroelectric liquid crystal (FLC) is shown. As FLC a chiral smectic liquid crystal is employed to exhibit a bistability between a pair of substrates which have easy polarization axes normal to each other. Informations to be recorded are written on the disc in terms of a binary system by use of the bistability.

4 Claims, 4 Drawing Sheets