| 摘要 |
PURPOSE:To furnish a synchronous motor driving unit for a clock with a sufficient self-starting capability by employing a motor driving coil consisting of a synchronous driving coil member and a starting coil member, and using the former coil member for synchronously rotating a motor in an ordinary manner with a small torque and the latter coil member for starting the motor with a large torque. CONSTITUTION:When a power source is turned on, a start detecting signal is output from an AND-gate 64 of a start controlling signal generating circuit 36. As a result, a driving pulse array of 16Hz is supplied to a second driving coil 22 for a period of time set by a counter 42 forming a timer circuit in a start controlling signal generating circuit 34, while a large combined torque from a start-driving coil consisting of drive coil members 20, 22 is supplied to a rotor. A synchronous motor then continues to be rotated stably at a constant speed with a small torque of the first drive coil member 20 constituting a synchronous driving coil member. When indicating pointers start to run, a large torque is supplied to the rotor in the same manner as in a case where a clock is started. |
