| 摘要 |
PURPOSE:To make a master lens group or a part of it perform minute modulating operation and focusing operation by providing a driving element that moves a movable lens in the direction of the optical axis while giving the lens minute vibration. CONSTITUTION:A master lens group 11 that forms a zoom lens with a focus ring 12 can be moved freely in the direction of optical axis by a driving element 13 having a rotor 15. By switching the electrode of a stator 14 of a surface waveform ultrasonic motor, being a driving element 13, the direction of rotation of the rotor 15 is changed, and the master lens group 11 causes minute vibration longitudinally, and the focus position on the image pickup face of an image pickup device 16 changes minutely, and the higher harmonic component of video signals causes minute change periodically. The amount and direction of out-of-focus is calculated by a signal processing circuit 17, and the master lens group 11 is vibrated minutely by the driving element 13 and at the same time, the amount of amplitude is made larger in the direction of out-of-focus, and thereby, the master lens group 11 is moved in the direction of focusing. Thus, the focusing can be made automatically. |
