CCD imager with modified scanning circuitry for increasing vertical field/frame transfer time

摘要

A CCD imager is used in a television camera which generates signals for use with a particular television standard, such as the proposed U.S. HDTV production standard. The imager includes a light-sensitive A register which generates signal in the form of charge during an integrating interval, a B charge storage register into which the charge is transferred during a pull-down interval, and a horizontal shift register coupled to the last row of the B register, into which the charges are simultaneously coupled, and serially read. The video signals produced by the imager are subject to distortion caused by incomplete charge transfer in the pull-down interval and crosstalk noise resulting from gating the clock signals to the horizontal shift register on and off. Vertical transfer distortion is reduced by reading the horizontal lines from the horizontal shift register with reduced intervals between the active portions, which allows the pull-down interval to be increased. The increased pull-down interval allows use of a lower frequency signal for the vertical transfer clock signal. Crosstalk noise is reduced by applying the horizontal shift register clock to the horizontal shift register continuously.