AUTOMATIC FOCUS ADJUSTMENT DEVICE

摘要

PURPOSE:To reduce power consumption and to improve the durability of the device by detecting an external disturbance of a high frequency component of a video and assigning a means to each of state of the external disturbance to designate the operating mode of the automatic focus mode thereby reducing the number of times of system operation. CONSTITUTION:An object image made incident from an image pickup lens 1 and formed onto a CCD 2 is supplied to a camera system signal processing circuit 3 as a luminance signal and inputted to an automatic focus control system 4 as a video signal. The high frequency component of the luminance signal of the video signal is extracted by a band pass filter section 41. The high frequency component passing through a low pass filter whose cut-off frequency is 200kHz-1.5MHz for the purpose of synchronization and passing through a high pass filter whose cut-off frequency is 400kHz-1.5MHz for the purpose of high focus accuracy is selected properly by a switch, and the component is rectified by a half wave rectifier and digitized by an A/D converter 42 in 3.58MHz.6-bit. The high frequency component in a focus detection area equivalent to 1/4 of the entire screen area is integrated from the high frequency component signal by an integration device 43 comprising a gate array and the result is fed to a microcomputer 44.