Television field-recognition apparatus

Claim 1

TELEVISION FIELD-RECOGNITION APPARATUS COMPRISING, IN COMBINATION: A SOURCE OF MIXED TELEVISION SYNCHRONIZING SIGNALS INCLUDING HORIZONTAL SYNCHRONIZING SIGNALS AND VERTICAL SYNCHRONIZING SIGNALS EACH COMPRISING A TRAIN OF BROAD PULSES, SAID VERTICAL SYNCHRONIZING SIGNALS BEING DIFFERENTLY TIMED WITH RESPECT TO SAID HORIZONTAL SYNCHRONIZING SIGNALS IN ODD AND IN EVEN FIELDS; CIRCUIT MEANS OPERATING WHEN FED WITH A SIGNAL INCLUDING VERTICAL SYNCHRONIZING SIGNALS TO YIELD OUTPUT IMPULSES CORRESPONDING TO THE LEADING EDGE OF THE FIRST BROAD PULSE OF A VERTICAL SYNCHRONIZING SIGNAL; MEANS FOR APPLYING SAID TELEVISION SYNCHRONIZING SIGNAL TO SAID CIRCUIT MEANS; FURTHER CIRCUIT MEANS OPERATING WHEN FED WITH A SIGNAL INCLUDING HORIZONTAL SYNCHRONIZING SIGNALS TO DEVELOP A TWO-VALUED SIGNAL HAVING A FIRST VALUE DURING A PERIOD APPROXIMATING THE FIRST HALF OF EACH HORIZONTAL PERIOD AND HAVING A SECOND VALUE AT OTHER TIMES; MEANS FOR APPLYING SAID MIXED SYNCHRONIZING SIGNALS TO SAID FURTHER CIRCUIT MEANS; GATE MEANS HAVING FIRST AND SECOND INPUTS AND AN OUTPUT AND OPERATING TO YIELD A SIGNAL AT SAID OUTPUT WHEN AN IMPULSE IS APPLIED TO SAID FIRST INPUT ONLY WHEN A SIGNAL APPLIED TO SAID SECOND INPUT HAS A PREDETERMINED ONE OF SAID VALUES; MEANS FOR APPLYING SAID OUTPUT IMPULSES TO SAID FIRST INPUT; AND MEANS FOR APPLYING SAID TWO-VALUED SIGNAL TO SAID SECOND INPUT, WHEREBY SAID GATE MEANS YIELDS SIGNALS CORRESPONDING WITH A PREDETERMINED SET OF SAID ODD OR EVEN FIELDS.