Pressure sensor with a ferroelectric liquid crystal layer

• US 4,875,378 A
• Filed: 01/29/1988
• Issued: 10/24/1989
• Est. Priority Date: 02/19/1987
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Mase, Akira, Yamazaki, Shunpei
• Primary Examiner(s): ORSINO JR, JOSEPH
• Assistant Examiner(s): Chen, Hollis T.
• Application Number:
  US07/150,150
• Time in Patent Office: 634 Days
• Field of Search: 340/365 A, 310/338, 310/800, 310/311, 310/366, 310/339, 350/333, 350/350 R, 350/350 S, 73/862.04
• US Class Current: 73/862.046
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 30/857 Macromolecular compositions
• CPC Class Codes: Y10S 73/04 Piezoelectric

Abstract

A new type of pressure sensor is disclosed here. The sensor is composed of a pair of glass substrates and a ferroelectric liquid crystal which is interposed between the substrates and exhibits piezoelectric effect. Because of crystalline property in liquid phase, the piezoelectric medium can be easily disposed and aligned between the substrates in light of the orientation of the surface contiguous to the liquid crystal layer.

Claims

1. A pressure sensor comprising:

a pair of substrates;

a ferroelectric liquid crystal layer interposed between the substrates;

an electrode arrangement formed on the substrates and including at least one pair of electrodes located on the both sides of said liquid crystal layer to pick up the voltage generated across said liquid crystal layer; and

a means for detecting the voltage induced between said pair of electrodes, said voltage being induced by piezoelectric effect by piezoelectric effect.

2. A pressure sensor comprising:

a pair of substrates;

a ferroelectric liquid crystal layer interposed between said pair of substrates;

a plurality of column electrodes and one or more row electrode arranged on the opposed insides of said substrates in a matrix form; and

a detecting means connected with said column and row electrodes for detecting the piezoelectric voltage produced between particular column and row electrodes.

3. The sensor of claim 2 further comprising a driver means connected with said column and row electrodes for causing the display of a visual information in terms of the optical property of the liquid crystal.

4. The sensor of claim 3 wherein said liquid crystal layer is composed of at least a chiral smectic liquid crystal.

5. The sensor of claim 4 wherein at least one inside of said substrates is provided with an orientation control surface.

6. The sensor of claim 5 wherein said orientation control surface is produced by rubbing treatment.