| 摘要 |
PURPOSE:To reduce the power consumption and to prevent overload on a driving machine system by finding a power turning-on/off ratio in which a gear row can be first driven at the time of a maximum voltage value which a supply voltage can take and surely starting a motor in this ratio and determining the upper limit value of the power turning-on/off ratio which can be used in accordance with the value of the power turning-on/off ratio at this start time. CONSTITUTION:With respect to adjustment of the driving force of a motor 3, the power supplied to the motor 3 is periodically turned on and off, and a ratio of the turning-on period to the turning-off period is changed. In this case, power is supplied to the motor 3 in the power turning-on/off ratio, in which a gear row 4 can be first driven at the time of a maximum voltage value which the supply voltage can take at the time of starting to drive a distance ring, to try driving of the motor 3; and when rotation of the motor 3 is not detected, the power turning-on/off ratio is gradually changed till rotation of the motor is detected, and the power turning-on/off obtained at the time of detecting rotation is defined as the second turning-on/off ratio, and the third turning-on/off ratio determined in accordance with the second turning-on/off ratio is set as the upper limit to supply power to the motor for the purpose of driving a lens. Thus, overload on the driving transmission system such as the gear row 4 is prevented. |
