Patent ID: 6850026

Claim:
A stepping motor driver for controlling a phase of a voltage applied to the motor with reference to a rotational angle of a rotor comprising: an angle computing means that receives rotor position detection signals from a rotor position detection means and calculates a detected angle representing said rotational angle of said rotor; and a lead angle controller that generates a corrected command angle based on the difference between a command angle given from outside and said detected angle, wherein said lead angle controller includes means for calculating an angle deviation that is the difference between said command angle and said detected angle, means for comparing said angle deviation with a predetermined value, means for outputting said command angle as said corrected command angle if said angle deviation is less than said predetermined value, and for outputting a value obtained by adding an approximated lead angle to said detected angle as said corrected command angle if said angle deviation is greater than, or equal to, said predetermined value, and wherein said phase of said voltage applied to the motor is controlled according to said corrected command angle.