Synchronizing signal separation circuit

Claim 2

A synchronizing signal separation circuit for use in a television receiver having horizontal and vertical synchronization requirements comprising: amplifier means for separating synchronizing signals from video information signals and providing an output containing both vertical and horizontal synchronizing signals; passive high pass filter means responsive to said amplifier means output to pass only horizontal synchronizing signals; active low pass filter means comprising a switching transistor in a common emitter configuration having an input and an output, said input coupled to said amplifier means output; and a capacitor connected in shunt with said input.

Claim 3

The circuit of claim 1 wherein said amplifier means comprises threshold means responsive to incoming signals to pass only those signals having a magnitude exceeding a first predetermined value and limiter means for limiting the magnitude of the signals passed by said amplifier means to less than a second predetermined value.

Claim 4

The circuit of claim 2 wherein said amplifier means further comprises means for inverting the signals passed by said threshold and said limiting means.

Claim 5

The circuit of claim 1 further comprising resistance means in parallel with said capacitor, the time constant of said resistance means and capacitor parallel circuit being sufficiently short that the horizontal synchronizing signals are insufficient to charge said capacitor to a voltage sufficient to trigger said switching transistor.

Claim 6

In a synchronizing signal separation circuit for a television receiver having means for separating vertical and horizontal synchronizing signals from received video signals, an improved circuit for providing an output synchronizing signal only in response to the vertical synchronizing signals at its input comprising: a threshold device having an input and an output and adapted to provide an output pulse only when the voltage at its input exceeds a predetermined threshold level; and a resistor and a capacitor connected in parallel, said parallel combination connected in parallel with said threshold device input and having a time constant sufficiently small to prevent the voltage across said capacitor exceeding said predetermined threshold in response to the receipt of horizontal synchronizing pulses, said time constant being sufficiently long that a burst of vertical synchronizing pulses builds up a voltage on said capacitor which exceeds said predetermined threshold.

Claim 7

In a synchronizing signal separation circuit for a television receiver having means for separating vertical and horizontal synchronizing signals from received video signals, an improved circuit for providing an output synchronizing signal only in response to the vertical synchronizing signals at its input comprising: a threshold device having an input and an output and adapted to provide an output pulse only when the voltage at its input exceeds a predetermined threshold level; and a resistor and a capacitor connected in parallel, said parallel combination connected in parallel with said threshold device input and having a time constant sufficiently small to prevent the voltage across said capacitor exceeding said predetermined threshold in response to the receipt of horizontal synchronizing pulses, said time constant being sufficiently long that a burst of vertical synchronizing pulses builds up a voltage on said capacitor which exceeds said predetermined threshold.