Camera pickup tube circuit for automatically suppressing excessive highlights in response to their occurrence

A tube circuit for automatically enabling the excessive highlight suppression mode of operation of a camera pickup tube in response to a video signal level indicative of excessive highlights in the viewed scene, wherein the pickup tube includes an electrode configuration with a control grid, an auxiliary grid, and a cathode, adapted to generate a high intensity beam for bombarding the tube target during the line flyback period, comprising the combination of:

• highlight detector means including level detector means formed of threshold means coupled to the tube target for detecting only the excessive video signal corresponding to the excessive highlights, and for automatically generating an enable command only in response to the existence of the excessive highlights;
• and
• control/timing means coupled to the detector means and also to input signals including vertical and horizontal blanking and deflection timing signals, and a beam current control signal for generating and introducing selected signals to the control grid, to the auxiliary grid and to the cathode in response to the enable command and to a subsequent vertical deflection timing signal to enable the excessive highlights suppression mode of operation of the pickup tube during a selected portion of the horizontal blanking interval corresponding to the line flyback period occurring after the vertical deflection timing signal.

A tube circuit for automatically enabling the excessive highlight suppression mode of operation of a camera pickup tube in response to a video signal level indicative of excessive highlights in the viewed scene, wherein the pickup tube is provided with an electrode configuration having a control grid, an auxiliary grid, and a cathode which is adapted to generate a high intensity beam for bombarding the tube target during the line flyback period, comprising:

• highlight detector means including level detector means in the form of threshold means having its input coupled to the tube target for detecting only the excessive video signal corresponding to the excessive highlights, and for automatically generating at its output an enable command only in response to the existence of the excessive highlights;
• and
• control/timing means coupled to the output of the highlight detector means and also to input signals including vertical and horizontal blanking and deflection timing signals, and a beam current control signal for generating and introducing selected signals to the control grid, to the auxiliary grid and to the cathode in response to the enable command to enable the excessive highlights suppression mode of operation of the pickup tube during a selected portion of the line flyback period, said control/timing means including;
• logic/timing pulse waveform generating means coupled to the output of the highlight detector means and including,
• means responsive to the vertical deflection timing signal for re-clocking the enable command to initiate same during the vertical blanking,
• means for generating an interrupted blanking signal,
• means for generating control grid pulse signals,
• means for generating an erase level logic signal, and
• means for generating an auxiliary grid logic signal,
• said last four signal generating means being responsive to the re-clocked enable command and to the horizontal and vertical deflection timing signals for initiating the excessive highlight suppression mode of tube operation during the selected portion of the horizontal blanking interval corresponding to the line flyback period.