Abstract: An apparatus and a method for automatically focusing an object in a video cameras comprises a solid state image sensor for converting a light beam transmitted through a lens and an iris into an electrical signal, an amplifier for amplifying a video signal from the solid state image sensor, a video signal processor for processing the video signal amplified by the amplifier, high pass filters for high pass filtering the video signal amplified by the amplifier, a video divider for dividing the video signals filtered by the high pass filters in the unit of field, a low pass filter for low pass filtering the video signals divided by the video divider, an A/D converter for converting the video signals filtered by the low pass filter into digital signals, an integrator for integrating the digital signals from the A/D converter to output video detect data, and a microprocessor for checking a level of the video detect data from the integrator and outputting a control signal to a lens motor driver in accordance with th

Abstract: A picture interphone system uses existing an TV and camcorder without any special equipment. The system is able to record a picture of a visitor while the user is not at home or when the user wants to record the picture of the visitor. The camcorder and the TV are turned on by the signal of a switch pushed by the visitor and automatically turns off after the visitor has left.