Patent ID: 6900612

Claim:
A method of driving a stepping motor, the method comprising: providing a stepping motor including a permanent magnet type rotor with a plurality of poles secured to a rotating shaft and a stator having stator magnetic poles with stator magnetic pole teeth in which excitation windings are wound around a plurality of magnetic poles in a star or delta connection, wherein the rotor is magnetized in different directions alternately circumferentially to satisfy the following equation: M=4F/3 where M is the number of poles of the rotor and F is the number of the stator magnetic poles, the rotor is cylindrical in shape with the stator rotatably disposed inside, disposed opposing the surfaces of the stator magnetic pole teeth through an air gap which is of a uniform dimension throughout the circumference between the surfaces of the stator magnetic pole teeth of the stator and the rotor, and the surface magnetic flux distribution thereof has a substantially sinusoidal wave form circumferentially; and a driving means to impress a driving signal in a three-phase single-two-phase excitation mode to three excitation feeding terminals and to control rotation of the stepping motor by a signal from a leakage flux detector which detects magnetic flux leaking from a notch provided in a rotor yoke: driving the stepping motor by impressing the driving signal in the three-phase single-two-phase excitation mode to the three excitation feeding terminals in a star or delta connection wound on a plurality of magnetic poles of the stepping motor, detecting signals from the leakage flux detector and comparing a changing speed of the signals from the leakage flux detector with the driving signal of the stepping motor to generate a comparison result; stopping supply of the driving signal of the stepping motor when the comparison result is equal to or greater than a certain value, supplying the driving signals again after a predetermined time, repeating stopping and supplying processes of the driving signal for a predetermined number of times; and issuing a warning when normal rotation is not obtained.