International Standard Electric Corporation

Kenneth A Arton

Peter F Blomley

George H Rokos

Edward J Whittaker

Andrew Paul Lefevre

Alexander Douglas Odell

John M Young

An integrated circuit for a telephone instrument provides the basic (POT) service requirement. The transmit and receive channels of the circuit may be fed via controlled attenuators incorporated in a first ancillary circuit to provide hands-free operation. The circuit also includes a current-limited power supply whereby connection to a second ancillary circuit, including an audio amplifier, may be effected to provide loudspeaker operation.

Telephone instrument circuit

In a matrix array liquid crystal display on silicon with an a.c. drive involving periodic reversal of the potential of the counter-electrode this reversal is liable to produce a significant r.m.s. error voltage at each reversal. The OFF element error voltage is effectively eliminated by blanking all picture elements at the commencement of each reversal, and the ON error voltage more evenly shared by making this reversal occur after a non-integral number of frame scans.

Matrix addressing of display devices

This invention relates to a Schmitt trigger circuit, and particularly to a Schmitt trigger circuit comprising MOS transistors. The all MOS transistor Schmitt trigger circuit has a first MOS input inverting amplifier regeneratively coupled with a further MOS transistor to provide the requisite positive feedback voltage, and a second MOS input inverting amplifier, not in the feedback loop but having the feedback voltage also applied thereto, the output being taken from the second inverter. Separation of output from the feedback loop gives flexible control of input triggering points and output characteristics. This circuit is intended for use in a MOS IC telephone switching cross-point switch.

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Harlow, United Kingdom

Kenneth A Arton