Switching of thermochromic and pressure sensitive films with sur

Details Switching of thermochromic and pressure sensitive films with sur Switching of thermochromic and pressure sensitive films with sur

Filed on

1979-04-23

Date issued

1980-11-25

Examiner

Trafton, David L.

Patent Class

Communications: electrical

SubClass

Land vehicle alarms or indicators

SubSubClass

Internal alarm or indicator responsive to a condition of the...

Other Related Categories

340783, 340713, 350353, 350358, 358235, G09F 900

Type

Patent

Status

active

Patent number

042361567

Description

ABSTRACT:
An apparatus for "fast erase" of thermochromic information displays is provided. A piezoelectric substrate (10) has a thin film (18) of vanadium dioxide deposited on the surface thereof. The film undergoes marked increases in reflectance at any region thereof experiencing thermal heating in excess of its predetermined transition temperature. An ultrasonic surface acoustic wave transducer (11) is provided which includes a pair of electrodes (12, 14) spaced apart in substantially parallel relation on the surface of the substrate (10) such that application of an RF signal across the electrodes (12, 14) causes deformation of the substrate to generate surface acoustic waves on the surface thereof and in the film to counteract built-in strains in the film to erase images written into the film.
A solid state information display using pressure sensitive material is also disclosed. A thin film of samarium sulphide (30) is deposited on the surface of a piezoelectric substrate (10) such as lithium niobate. The film undergoes marked increases in reflectance at any region thereof subjected to a pressure in excess of a predetermined threshold pressure. Three surface acoustic wave transducers (34, 36, 38) are provided on the substrate (10) positioned relative to the film such that eastwardly, westwardly and northwardly traveling surface waves are produced in the film. A video signal generator (40) is provided for each of the transducers with delay units (42) for launching pulses at preselected times in the film such that a point of pressure in excess of the threshold pressure can be selectively created to increase the reflectance of the film at that point.

REFERENCES:
patent: 3438022 (1969-04-01), Jeeg et al.
patent: 3633996 (1972-01-01), Lean et al.
patent: 3736044 (1973-05-01), Lean et al.
patent: 3789421 (1974-01-01), Chivian et al.
patent: 3831165 (1974-08-01), Chivian et al.
patent: 4009488 (1977-02-01), Smith
patent: 4065791 (1977-12-01), Kowel et al.
patent: 4069507 (1978-01-01), Defranould et al.

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