At&t Bell Laboratories

Bell Telephone Laboratories

John Frederick Jarvis

Robert G Swartz

Bruce A Wooley

An integrated array of pressure transducers capable of producing an analog output voltage representative of the applied pressure is proposed. The individual transducing elements (16) are defined by a three-layer structure including a thin layer of piezoelectric material (10) disposed between a reference potential plate (12) and a plurality of electrodes (15) contained in a silicon substrate (14). A force applied to a localized portion of the reference plate will cause a deflection of the piezoelectric material towards the electrodes on the substrate, inducing a capacitive charge on the electrode in the localized area. This capacitance is stores at a node A associated with the transducing element, and may be interrogated by a sensing circuit (18) located in the silicon substrate. Since the induced charge is directly proportional to the applied force, a measurement of the output voltage from node A will yield a direct indication of the localized force applied to the sensor.

Analog integrated circuit pressure sensor

Continuous tone images are displayed on a bi-level display device by establishing thresholds for each display element and actuating a particular element when its intensity .phi. bears a predetermine relationship to the established threshold. Thresholds .phi..sub.T are established by determining the average intensity .phi. of picture elements in the neighborhood of a particular display element, and by constraining the average to a narrower range according to a single value function of .phi. such as ##EQU1## WHERE .phi..sub.MAX IS THE MAXIMUM INTENSITY POSSIBLE AND .gamma. IS A CONSTANT WHICH CAN BE DETERMINED SUBJECTIVELY OR WHICH CAN BE RELATED TO THE NOISE IN THE PICTURE AREA.

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Fair Haven, NJ, United States of America

John Frederick Jarvis