Angular position detector.

摘要

A transducer formed of one or more electrode arrays is positioned in confronting relation and parallel to the plane of rotation of one or more rotating members. A plurality of phase modulated, two-phase, square wave drive signals of the same amplitude and frequency are applied to each electrode. The signals are combined at a central node or electrode to form, as a result of the signal, the superposition of the algebraic sum of all drive signal pairs. Samples of the resultant signal taken at the same frequency and of a duration of less than one-half the duration of the drive signal period provide a multi-step, synchronously detected signal. The detected signal is a multi-step approximation to a sine wave, the phase angle thereof relative to a timing point being proportional to the angular position of the rotating member. The amplitudes and phase shifts of the multi-step detected signal are then reduced to a plurality of vectors, from which two orthogonal vectors are produced which may be mathematically reduced to the amplitude and phase angle of the aforesaid sine wave. The phase angle is transformed or converted into a binary representation of the hand position. The amplitude of the sine wave is utilized in conjunction with a stored look-up table to generate a binary compensation value for the aforesaid binary representation, which compensation is representative of a variance in the detected signal as a result of the distance between the transducer and the rotating member. A second binary interdial compensation value is generated to correct for errors in the mechanical misalignments of certain ones of the rotating members which would normally lead to ambiguities in the dial readings. The entire procedure is controlled by a unique program which incorporates a special numerical code which ultimately provides an output signal that is the BCD equivalent of the integer value representative of the position of the rotating member.