| 摘要 |
PURPOSE:To reduce the electric current consumption of a step motor by driving the step motor by difference driving force and then by changing the driving force in accordance with its load. CONSTITUTION:After a driving signal is applied to electromagnetic coil 5a of step motor 5, coil 5a is changed over from the closed-circuit state to the open-circuit state, load detection 6 is performed on the basis of an induced voltage generated at the point of the switching and in accordance with the state of its load, the driving signal is converted 3 into at least three kinds of driving force. In this case, when the step motor is driven by driving force other than minimum driving force and minimum one, switching from the closed-circuit state to the open-circuit state is performed at least twice after the driving signal is applied to electromagnetic coil 5a of step motor 5. On the basis of at least one of induced voltages generated every time the switching is performed in accordance with the load, the driving signal is converted into driving force one rank below and on the basis of at least one of remaining voltages, the driving signal is converted into driving force one rank above. |
