Patent ID: 7283428

Claim:
A step motor drive unit comprising: a step motor having a stator, a coil wound in the stator and a rotor rotatably held in the stator; and a drive circuit for supp1lying a drive pulse whose polarity alternately differs to the coil and which generates a magnetic flux whose polarity alternately differs in the stator by supplying the drive pulse to the coil from the drive circuit, thereby rotation-driving the rotor in the same direction by a predetermined angle at a time by each of the magnetic flux whose polarity differs; and a control means which, after detecting the fact that the rotor was not rotated by a first normal drive pulse of a predetermined energy and rotation-driving the rotor by a correction drive pulse whose energy is larger than the 1st normal drive pulse, rotation-drives the rotor by a second normal drive pulse whose polarity differs from the correction drive pulse and whose energy is larger than the first normal drive pulse and smaller than the correction drive pulse.