| 摘要 |
PURPOSE:To prevent heat generation of a control motor and to enhance reliability of a copying apparatus, by detecting the movement region of a zoom lens, etc, and turning off the power supply of excitation of a numerical control motor for moving the lenses during suspension. CONSTITUTION:Rotation of a screw driven by a numerical control motor moves a zoom lens system linearly in the optical axis direction together with its holding mechanism through screw engagement. The movement region of said system is detected with a detection piece 14 moving unitedly with the holding mechanism, and with a fixed detector 15. A detection signal is turned to a high or low level in accordance with the standard of an equal size region, a magnification region, and a size reduction region. After the system is temporarily returned to the standard equal size position using this signal change, the numerical control motor is adjusted by pulses of desired step numbers to stop the system at the desired position. At that time, the excitation current of the motor is cut off, heat generation of the motor to be suppressed, and reliability of all the copying apparatus to be prevented from lowering. |
