Angle sensor with inductive coil coupling

Claim 1

An angle sensor comprising a rotatable transmitter part; a stationary receiver part; a support holding said rotatable transmitter part facing said stationary receiver part; and wherein the rotatable transmitter part comprises a coil which is connectable to a source of alternating current, the coil being spirally wound on said rotatable transmitter part and extending on both sides of an axis of rotation, the rotatable transmitter part being rotatable about the axis of rotation, a longitudinal axis of said coil extending transverse to said axis of rotation; the stationary receiver part comprises a field sensor for electromagnetic fields, the field sensor being located opposite to and spaced from the coil and extending on both sides of the rotational axis transverse thereto; the angle sensor further comprising a rotary transformer having a primary winding and a secondary winding; and a housing enclosing said stationary receiver part and supporting said primary winding; and wherein said coil is connected to said secondary winding; said field sensor of said stationary receiver part includes two coils; said angle sensor further comprising a circuit connected to said two coils of said stationary part, said circuit including two FET switches, a set of resistors, and two operational amplifiers; an oscillator feeding the primary winding of the rotary transformer; a phase-related scanning signal generator connected to said primary winding, said phase-related scanning signal generator being controlled by the oscillator and being connected to one control electrode each of the FET switches; and wherein each said FET switch is connected, in series with a coil of the stationary receiver part and said set of resistors, to the inputs of the operational amplifiers, a variable gain and the superimposable voltage of the operational amplifiers serving for adjustment of compensation values to an angle measurement of the angle sensor; and an output of said field sensor is connected to said circuit, said circuit having circuit components for at least partially compensating for deviations, caused by asymmetries or inaccuracies in an arrangement of the transmitter and receiver parts, of an output signal of the stationary receiver part from a fixed relationship between the angular position of the rotatable transmitter part and an output signal of the stationary receiver part, said circuit components being components for compensating for asymmetries and/or signal amplitudes and/or coil-angle stagger.