Patent ID: 6555985
Filing Date: 2003-04-29
Classification: H02P

Abstract:
A stepping motor control device, comprising:a stepping motor including a rotor having magnetic poles equally spaced in a circumferential direction at intervals of an angle of &thgr;Â°, and M-phase excitation coils (M is an integer greater than or equal to two, and the M-phase does not include a reverse phase); driving means for supplying a driving current having a plurality of levels to the excitation coil in accordance with command values; command value generating means for generating the command value, where the driving current takes a different value having at least K levels (K is an integer); rotational angle detecting means for generating n pulses (n is an integer satisfying n&gE;MÂ·K) corresponding to rotation of the rotor; and excitation switching timing generating means for selecting pulses from the n pulses of the rotational angle detecting means in a predetermined order, and generating an excitation switching timing in the K levels to each M-phase excitation coil, wherein in accordance with an output of the excitation switching timing generating means, the command value generating means switches between a first command value for supplying a positive first driving current to the excitation coils, a second command value for supplying a negative second driving current whose direction is reverse to that of the first driving current to the excitation coils, and a third command value for supplying a third driving current taking a value between the first and second driving currents to the excitation coils, where K is three or more, and generates a command value which causes a lead angle in excitation to be increased in such a direction as to compensate a delay in excitation due to inductance of the excitation coils, and thereafter, generates a command value which causes a lead angle in excitation to be smaller than that lead angle.