Patent ID: 6380757
Filing Date: 2002-04-30
Classification: G01R

Abstract:
Position detection circuitry for a motor drive system including a DC motor and a drive control circuit for selectively coupling said DC motor to a power source, comprising:a sensor responsive to a current through said DC motor for producing voltage pulses corresponding to pulses in such current; a pulse recognition circuit coupled to said sensor for filtering and amplifying voltage pulses received at a pulse recognition circuit input; a pulse counting circuit responsive to filtered and amplified pulses produced by said pulse recognition circuit, for forming standard pulses in coincidence with the filtered and amplified pulses, and counting such standard pulses to provide a pulse count representative of motor position; and a start pulse rejection circuit responsive to an output of said drive control circuit for rendering at least one of the pulse recognition circuit and the pulse counting circuit inoperative for a predetermined time interval upon the coupling of said DC motor to said power source so that start-up voltage pulses produced by said sensor upon the coupling of said DC motor to said power source do not affect said pulse count.