Electrical resolver means

Claim 1

A SHAFT ANGLE ELECTRICAL RESOLVER FOR DERIVING A PORTION OF A TRIGONOMETRIC FUNCTION OF A GIVEN SHAFT ANGLE COMPRISING A SHAFT, A FLAT SURFACE HAVING A RESISTIVE COATING PLACED THEREON OF A PREDETERMINED UNIFORM RESISTIVITY PER UNIT AREA, A PAIR OF SPACED PARALLEL CONDUCTIVE ELECTRODES FASTENED TO AND CONDUCTIVELY COOPERATING WITH SAID RESISTIVE COATED SURFACE, A WIPER ARM PIVOTALLY MOUNTED ON SAID RESISTIVE COATED SURFACE AND ELECTRICALLY INSULATED THEREFROM AND ROTATABLE IN ACCORDANCE WITH SAID SHAFT ANGLE, A WIPER CONTACT MOUNTED ON THE END OF SID WIPER ARM FOR MAINTAINING A SLIDABLE CONDUCTIVE CONTACT ON SAID RESISTIVE COATING, THE POSITION OF SAID PIVOTAL MOUNTING AND THE LENGTH OF SAID WIPER ARM BEING SELECTED SO THAT SAID WIPER CONTACT MAKES EFFECTIVE CONDUCTIVE CONTACT ALTERNATELY WITH THE TWO PARALLEL ELECTRODES AT 180 DEGREES ANGULAR POSITIONS OF SAID SHAFT, SAID SHAFT DRIVING SAID WIPER BEING ROTATABLE THROUGH 360 DEGREES, A SOURCE OF ELECTRICAL ENERGY BEING CONDUCTIVELY CONNECTED ACROSS SAID PAIR OF ELECTRODES, A SUMMING AMPLIFIER HAVING AT LEAST TWO SUMMING INPUTS, ONE OF SAID SUMMING INPUTS BEING CONDUCTIVELY CONNECTED TO SAID WIPER CONTACT, THE OTHER OF SAID SUMMING INPUTS BEING CONNECTED TO AN ELECTRICAL ENERGY SOURCE EQUAL IN VOLTAGE AND OPPOSITE IN POLARITY TO THAT PRESENT IN THE RESISTIVE COATING IMMEDIATELY ADJACENT SAID SHAFT POSITION OF SAID WIPER ARM, THE OUTPUT OF SAID SUMMING AMPLIFIER MEANS PROVIDING AN ELECTRICAL SIGNAL WHICH IS A SINUSOIDAL FUNCTION OF THE ANGULAR POSITION OF SAID SHAFT.