To prevent erroneous detection of a rotation situation or generation of erroneous rotation even in the case where a magnetic field is present.
A stepping motor control circuit comprises: a rotation detection section which detects a rotation situation of a stepping motor 107 by detecting an induction signal exceeding a reference threshold voltage generated in a detection resistor during a detection phase including a plurality of detection cycles each formed from a first time for forming a first closed circuit including a driving coil of the stepping motor 107 and the detection resistor for detecting an induction signal generated by the stepping motor 107, and a second time for forming a second closed circuit from a driving coil and a low impedance element; a magnetic field detection circuit 116 which detects a magnetic field; and a control section which selects a driving pulse on the basis of the rotation situation of the stepping motor 107 detected by the rotation detection section, and drives the stepping motor 107 in accordance with the selected driving pulse. The rotation detection section changes a length of the detection cycle in accordance with whether the magnetic field detection circuit 116 detects a magnetic field exceeding a predetermined intensity.
| JP2676776 | [Title of Invention] Converter |
Noriaki Uchino
Nobuyuki Kimura