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Structure for Piezoelectric Echo Storage with Selective Erasure

IP.com Disclosure Number: IPCOM000086573D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 36K

Publishing Venue

IBM

Related People

Melcher, RL: AUTHOR [+3]

Abstract

This layered structure permits selective writing and erasing over portions of the entire piezoelectric crystal.

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Structure for Piezoelectric Echo Storage with Selective Erasure

This layered structure permits selective writing and erasing over portions of the entire piezoelectric crystal.

Heretofore, a number of structures have been developed in which phonons can be used in conjunction with a piezoelectric crystal and a second microwave electric field to produce holograms and holographic echoes [1,2,3]. However, there are two objections to the prior structures. In the first place, the second pulse covers the entire crystal which dissipates substantial energy. Secondly, selective erasing is difficult and generally cannot be done without impairing information not intended for erasure.

In the structure shown in Fig. 1, there are alternately deposited layers of metal film and piezoelectric material. Fabrication is by evaporation or chemical deposition. The storage region consists of alternate layers of metallic ground planes and piezoelectric crystal material, e.g., CdS. The metallic films are typically a few hundred angstroms thick, consisting, e.g., of copper or of a superconducting material such as Pb. The crystal regions are typically 50 microns thick to accommodate one or more bits of information from the acoustic pulse. An array of transducers on the front surface acts as the source of input information while adjacent ground planes are used to provide the second pulse (pump or write pulse). For this structure, information is processed in parallel from the array of transducers at the front surface. Information is stored by applying a pump pulse to two adjacent sets of metal planes, at a time consistent with the acoustic pulse reaching the region between the same two planes.

In this manner, the crystal stores information in a plane, with information arriving at a later time being stored, for example, in between successive planes, and successively closer to the transducer plane (Fig. 2). Timing pulses are shown for freezing in (storing)...