Method and circuit for controlling opening/closing of a camcorder iris

Abstract

A circuit for controlling the opening and closing of a camcorder iris diaphragm including a luminance signal detector for detecting a luminance signal from an image signal of an object received therein, a buffer for buffering the luminance signal from the luminance signal detector, a signal converter for converting the luminance signal from the buffer into a DC signal having a mean value level of the luminance signal, a differential amplifier for amplifying a level difference between the DC signal from the signal converter and a predetermined reference signal, a motor driver for receiving an output signal from the differential amplifier, as a negative (-) drive voltage signal, and a predetermined motor voltage signal, as a positive (+) drive voltage signal, and applying a level difference therebetween as a motor drive voltage signal to an iris motor, and a clipper connected for blocking the DC signal from the signal converter to the differential amplifier when its level is above a predetermined level and passing it from the signal converter to the differential amplifier when its level is below the predetermined level. Therefore, by preventing an oscillating operation of the iris diaphragm, the camcorder can take a picture of an object such as a light source of high brightness, without a separate mechanism such as a neutral density (ND) filter.