Patent ID: 6509709
Filing Date: 2003-01-21
Classification: H02P

Abstract:
A stepping motor controller comprising;an excitation signal generator that receives input pulse signals and generates excitation signals for controlling excitation sequence for a winding of a stepping motor, a switching circuit that receives said excitation signals and controls said excitation sequence for said winding of said stepping motor by a plurality of switching devices, a PWM constant current control circuit for controlling current flowing through said switching circuit to be a predetermined current set value, and a current sensor for detecting current flowing through said winding, characterized in that said stepping motor controller further comprises a motor detector portion comprising; a motor detector circuit that periodically transmits a control signal for generating a constant current for a predetermined time between said excitation signals for detecting the current resistance of the winding of the motor, a constant current generator that receives said control signal and generates said constant current to be supplied to said winding, a reference voltage generator that generates a reference voltage, a voltage comparator circuit that compares said reference voltage with a voltage drop at said winding indicative of said current resistance, and a current value setting signal generator circuit that transforms an output of said voltage comparator circuit into a current value setting signal for said PWM constant current control circuit, wherein an output of said current value setting signal generator circuit is connected to a current value setting terminal of said PWM constant current control circuit.