| 摘要 |
PURPOSE:To make it possible for a hand touching a lens-barrel to feel torque by performing frequency scanning again along with phase control when start of motor can not be confirmed through frequency scanning. CONSTITUTION:When an oscillation wave motor 9 does not start even if a microcomputor 1 performed frequency scanning gradually from high frequency to low frequency through a frequency divider/phase shifter 4 and the like, frequency scanning is performed again from the highest frequency within a setting range while furthermore phase control is performed by means of comparators 19, 20, and the like thus sustaining the frequency above the resonance frequency. When the movable part of a lens 14 is retained by hand, frequency begins to increase through phase control but the frequency begins to decrease, on the other hand, because the motor 9 is accelerated. Consequently, the frequency is settled within a predetermined range and the motor 9 is imparted with a constant frequency continuously and the control for starting the motor 9 sustains for a while. |
