Video playback system with flutter tolerant clamping

Claim 1

In a transducer system including a broadcast television receiver having a horizontal deflection circuit for generating an output horizontal sweep frequency signal, a horizontal control circuit for controlling the frequency of said horizontal deflection circuit, a picture signal circuit for transmitting a video picture signal, and a video display unit having a horizontal sweep connected with said horizontal deflection circuit and having a video intensity control connected with said video signal circuit for display of a picture transmitted thereto, a record medium having a recorded signal comprising video picture signals occurring during successive line scan intervals and perioDic horizontal synchronizing signals occurring at the beginning of the respective line scan intervals, a playback system for scanning said record medium and electrically reproducing said recorded signal with a degree of flutter substantially exceeding that of a broadcast television signal as received by said receiver, circuit means connected with said playback system, and with said horizontal control circuit and with said picture signal circuit, for transmitting the reproduced horizontal synchronizing signals to said horizontal control circuit such that the horizontal sweep of the display unit responds to and follows the flutter in the reproduced horizontal synchronizing signals, and for transmitting the reproduced video picture signal to the intensity control of the display unit. wherein the improvement comprises said circuit means including an output circuit point and a coupling capacitor for coupling the output of the playback system with the picture signal circuit via said output circuit point and a shunt clamping circuit connected with said output circuit point for controlling the direct current potential at said output circuit point at the beginning of each line scan interval, the clamping circuit including a first branch connected between said horizontal deflection circuit and said output circuit point for supplying a clamping pulse of predetermined duration from said horizontal deflection circuit to said output circuit point at the beginning of each line scan interval, and a second branch connected with said output circuit point and comprising a diode and potential establishing means in series for establishing a reference potential at said output circuit point in response to each of said clamping pulses, and said first branch having series resistance therein of substantial value to control the degree of clamping action.