Digitalized position control for a D.C. motor

Claim 1

A position control system for a D.C. motor comprising: rotary encoder means for developing an approximate sinusoidal position indicating analog signal in response to the rotation of a D.C. motor; slice level determination means for developing first and second sliced position indicating digital signals from said approximate sinusoidal position indicating analog signal; logic control means for determining the position of the D.C. motor and the rotating direction of the D.C. motor in response to said first and second sliced position indicating digital signals developed from said slice level determination means; and motor drive means for activating said D.C. motor in response to the determination conducted by said logic control means; said slice level determination means comprising, means for comparing said sinusoidal position indicating analog signal with a plurality of discrete voltages to develop a plurality of voltage attainment outputs, each representing that said sinusoidal position indicating analog signal has exceeded a said discrete voltage, and means for combining said voltage attainment outputs to produce said first and second sliced position indicating digital signals, said first and second sliced position indicating digital signals comprising pulse signals; said logic control means comprising, an up/down counter for developing coarse position signals for determining coarse position from said first and second sliced position indicating digital signals, and sliced position detection means for determining the position of said motor from said coarse position signals and said first and second sliced position indicating digital signals.