MOTOR DRIVE METHOD FOR AUTOMATIC FOCUS DEVICE

摘要

PURPOSE:To obtain timewise fluctuation of a video signal efficiently due to the vibration of lens by vibrating or moving stepwise a focusing mechanism in an optical axis direction and controlling its deflecting period and a high frequency component extracting period properly. CONSTITUTION:A master lens 2 of a zoom lens 1 is moved and vibrated along the optical axis direction to apply focusing. A video signal from an image pickup element 3 is fed to a video signal processing circuit 5 via a camera circuit 4. The high frequency component of the video signal is extracted by an extraction circuit 6 and the vibration frequency component of the master lens 2 is given to a synchronizing detector 8 and a focus discrimination circuit 9 via a band pass filter 7. The output is fed to a direction discriminator 10 and a feeding pulse generator 11 and a pulse generator 13 generates a pulse used for the vibration or movement of a pulse motor 15. Thus, the pulse motor 15 is driven in a way that the period extracting the high frequency component is a deviation required period of the master lens 2 or over.