Video signalling processing apparatus with noise protection

Claim 2

Signal-processing apparatus including in combination input circuit means; isolation circuit means having an input connection connected to the input circuit means and having a first output connection and a second output connection, said isolation circuit means being operable to produce a signal applied to the input connection by the input circuit means at the first and second output connections; peak detection means connected to the first output connection of the isolation circuit means, said peak-detection means including a charge storage means and circuit means, said circuit means being operable to charge the charge storage means to the peak voltage of the signal at the first output connection of the isolation circuit means; first comparison circuit means having a first input connection, a second input connection, and an output terminal; means connecting the second output connection of the isolation circuit means to the first input connection of the first comparison circuit means; means connected to the charge storage means and to the secoNd input connection of the first comparison circuit means for providing at the second input connection a voltage proportional to and less than the voltage on the charge storage means; said first comparison circuit means being operable to produce a first signal level at the output terminal when the voltage of the signal at its first input connection is less than the voltage at its second input connection and being operable to produce a second signal level at the output terminal when the voltage of the signal at its first input connection is greater than the voltage of the signal at its second input connection; second comparison circuit means having a first input connection connected to the input circuit means, a second input connection connected to the charge storage means, and an output connection, said second comparison circuit means being operable to produce a predetermined signal condition at its output connection when the voltage of the signal applied to its first input connection by the input circuit means is greater than the voltage at its second input connection; and switching circuit means connected to the output connection of the second comparison circuit means and associated with the isolation circuit means, said switching circuit means being operable to prevent the signal at the input connection of the isolation circuit means from being produced at the first and second output connections of the isolation circuit means in response to the presence of the predetermined signal condition at the output connection of the second comparison circuit means.

Claim 3

Signal-processing apparatus in accordance with claim 1 wherein: said charge storage means is a storage capacitance; and said circuit means of the peak-detection means is a differential amplifier circuit means having a first conduction condition during which current flows into said storage capacitance and a second conduction condition during which the circuit means provides a high impedance to current flow from the storage capacitance; said circuit means of the peak-detection means being biased to operate in the first conduction condition when the voltage at the first output connection of the isolation circuit means is greater than the voltage on the storage capacitance and being biased to operate in the second conduction condition when the voltage on the storage capacitance is greater than the voltage at the first output connection of the isolation circuit means.

Claim 4

Signal-processing apparatus in accordance with claim 2 wherein said first comparison circuit means includes: a first differential amplifier circuit means having a first conduction condition and a second conduction condition; and an output circuit means connected to the first differential amplifier circuit means and to the output terminal and being operable to produce the first signal level at the output terminal when the first differential amplifier circuit means is in the first conduction condition and being operable to produce the second signal level at the output terminal when the first differential amplifier circuit means is in the second conduction condition; said first differential amplifier circuit means being biased to operate in the first conduction condition when the voltage of the signal at the first input connection of the first comparison circuit means is less than the voltage at the second input connection of the first comparison circuit means and being biased to operate in the second conduction condition when the voltage of the signal at the first input connection of the first comparison circuit means is greater than the voltage of the signal at the second input connection of the first comparison circuit means.

Claim 5

Signal-processing apparatus in accordance with claim 3 wherein: said switching circuit means is operable when in a first conduction condition to permit the signal at the input connection of the isolation circuit means to be produced at the first and second output connEctions of the isolation circuit means and is operable when in a second conduction condition to prevent the signal at the input connection of the isolation circuit means from being produced at the first and second output connections of the isolation circuit means; and including: means for normally biasing the switching means to the first conduction condition; and circuit means connecting the output connection of the second comparison circuit means to the switching circuit means, said circuit means being operable to bias the switching means to the second conduction condition in response to the predetermined signal condition being present at the output connection of the second comparison circuit means and being operable to restore the switching circuit means to the normally biased first conduction condition a predetermined period of time after the predetermined signal condition appears at the output connection of the second comparison circuit means.

Claim 6

Signal-processing apparatus in accordance with claim 4 wherein: said second comparison circuit means includes a second differential amplifier circuit means having a first conduction condition and a second conduction condition, said second differential amplifier circuit means being operable to produce a first voltage level at the output connection of the second comparison circuit means when in the first conduction condition and being operable to produce a second voltage level at the output connection of the second comparison circuit means when in the second conduction condition, and means connecting the input circuit means to the first input connection of the second comparison circuit means and the storage capacitance to the second input connection of the second comparison circuit means and being operable to bias the second differential amplifier circuit means to the first conduction condition when the voltage at the first input connection of the second comparison circuit means is less than the voltage at the second input connection of the second comparison circuit means and being operable to bias the second differential amplifier circuit means to the second conduction condition when the voltage at the first input connection of the second comparison circuit means is greater than the voltage at the second input connection of the second comparison circuit means; said circuit means connecting the output connection of the second comparison circuit means to the switching circuit means includes a resistance-capacitance arrangement operable to bias the switching circuit means to the second conduction condition when the voltage at the output connection of the second comparison circuit means changes from the first voltage level to the second voltage level and to maintain the switching circuit means in the second conduction condition until the capacitance of the resistance-capacitance arrangement charges to a predetermined value; and said second comparison circuit means also includes means connected to the output connection of the second comparison circuit means and operable to discharge the capacitance of the resistance-capacitance arrangement when the voltage at the output connection changes from the second voltage level to the first voltage level.

Claim 7

Signal processing apparatus in accordance with claim 5 wherein said input circuit means includes: a differential amplifier circuit means having an input connection for applying input signals thereto and being operable to produce output signals at the input connection of the isolation circuit means and at the first input connection of the second comparison circuit means.

Claim 8

Signal processing apparatus in accordance with claim 6 wherein said isolation circuit means includes: a gating circuit means having an input terminal and being operable in response to a predetermined signal condition at the input terminal to prevent the signal at the input connection of the isolation circuit means from being produced at the first output connection of the isolation circuit means while permitting the signal to be produced at the second output connection of the isolation circuit means.

Claim 9

Video signal processing apparatus for separating the synchronizing pulses from the composite video signal in a television receiver including in combination: an input circuit means adapted to receive a composite video signal including the picture signal and synchronizing pulses; isolation circuit means having an input connection connected to the input circuit means and having a first output connection and a second output connection, said isolation circuit means being operable to produce the composite video signal at the first and second output connections; peak-detection means connected to the first output connection of the isolation circuit means, said peak-detection means including a charge storage means and circuit means, said circuit means being operable to charge the charge storage means to the peak voltage of the synchronizing pulses of the composite video signal at the first output connection of the isolation circuit means; synchronizing pulse comparator means having a first input connection, a second input connection and an output terminal; means connecting the second output connection of the isolation circuit means to the first input connection of the synchronizing pulse comparator means for providing the composite video signal at said first input connection; means connected to the charge storage means and to the second input connection of the synchronizing pulse comparator means for providing at said second input connection a voltage proportional to and less than the voltage on the charge storage means and greater than the maximum voltage of the picture signal portion of the composite video signal applied at the first input connection of the synchronizing pulse comparator means; said synchronizing pulse comparator means being operable to produce a first signal level at the output terminal when the voltage of the composite video signal at its first input connection is less than the voltage at its second input connection and being operable to produce a second signal level at the output terminal when the voltage of the composite video signal at its first input connection is greater than the voltage of the signal at its second input connection; noise comparator means having a first input connection connected to the input circuit means, a second input connection connected to the charge storage means, and an output connection, said noise comparator means being operable to produce a predetermined signal condition at its output connection when the voltage of the signal applied to its first input connection by the input circuit means is greater y a predetermined amount than the voltage at its second input connection, indicating the presence of noise in the input circuit means; and switching circuit means connected to the output connection of the noise comparator means and associated with the isolation circuit means, said switching circuit means being operable to prevent the composite video signal from being produced at the first and second output connections of the isolation circuit means in response to the presence of the predetermined signal condition at the output connection of the noise comparator means.

Claim 10

Video signal processing apparatus for separating the synchronizing pulses from the composite video signal in a television receiver including in combination: an input circuit means adapted to receive a composite video signal including the picture signal and synchronizing pulses; isolation circuit means having an input connection connected to the input circuit means and having a first output connection and a second output connection, said isolation circuit means being operable to produce the composite video signal at the first and second output connections; peak-detection means connected to the first output connection of the isolation circuit means, said peak-detection means including a charge storage means and circuit means, said circuit means being operable to charge the charge storage means to the peak voltage of the synchronizing pulses of the composite video signal at the first output connection of the isolation circuit means; synchronizing pulse comparator means having a first input connection, a second input connection and an output terminal; means connecting the second output connection of the isolation circuit means to the first input connection of the synchronizing pulse comparator means for providing the composite video signal at said first input connection; means connected to the charge storage means and to the second input connection of the synchronizing pulse comparator means for providing at said second input connection a voltage proportional to and less than the voltage on the charge storage means and greater than the maximum voltage of the picture signal portion of the composite video signal applied at the first input connection of the synchronizing pulse comparator means; said synchronizing pulse comparator means being operable to produce a first signal level at the output terminal when the voltage of the composite video signal at its first input connection is less than the voltage at its second input connection and being operable to produce a second signal level at the output terminal when the voltage of the composite video signal at its first input connection is greater than the voltage of the signal at its second input connection; noise comparator means having a first input connection connected to the input circuit means, a second input connection connected to the charge storage means, and an output connection, said noise comparator means being operable to produce a predetermined signal condition at its output connection when the voltage of the signal applied to its first input connection by the input circuit means is greater y a predetermined amount than the voltage at its second input connection, indicating the presence of noise in the input circuit means; and switching circuit means connected to the output connection of the noise comparator means and associated with the isolation circuit means, said switching circuit means being operable to prevent the composite video signal from being produced at the first and second output connections of the isolation circuit means in response to the presence of the predetermined signal condition at the output connection of the noise comparator means.

Claim 11

Video signal processing apparatus in accordance with claim 8 wherein: said charge storage means is a storage capacitance; and said circuit means of the peak-detection means is a differential amplifier circuit means having a first conduction condition during which current flows into said storage capacitance and a second conduction condition during which the circuit means provides a high impedance to current flow from the storage capacitance; said circuit means of the peak-detection means being biased to operate in the first conduction condition when the voltage at the first output connection of the isolation circuit means is greater than the voltage on the sTorage capacitance whereby the storage capacitance tends to become charged to the voltage of the synchronizing pulses of the composite video signal produced at the first output connection of the isolation circuit means, and being biased to operate in the second conduction condition when the voltage on the storage capacitance is greater than the voltage at the first output connection of the isolation circuit means whereby the charge in the storage capacitance does not tend to become dissipated through the circuit means when the storage capacitance has been charged to the voltage of the synchronizing pulses produced at the first output connection of the isolation circuit means and the picture signal portion of the composite video signal is being produced at the first output connection of the isolation circuit means.

Claim 12

Video signal processing apparatus in accordance with claim 9 wherein said synchronizing pulse comparator means includes: a first differential amplifier circuit means having a first conduction condition and a second conduction condition; and an output circuit means connected to the first differential amplifier circuit means and to the output terminal and being operable to produce the first signal level at the output terminal when the first differential amplifier circuit means is in the first conduction condition and being operable to produce the second signal level at the output terminal when the first differential amplifier circuit means is in the second conduction condition; said first differential amplifier circuit means being biased to operate in the first conduction condition when the voltage of the composite video signal at the first input connection of the synchronizing pulse comparator means is less than the voltage proportional to the voltage of the synchronizing pulses to which the storage capacitance is charged at the second input connection of the synchronizing pulse comparator means, and being biased to operate in the second conduction condition when the voltage of the composite video signal at the first input connection of the synchronizing pulse comparator means is greater than the voltage proportional to the voltage of the synchronizing pulses to which the storage capacitance is charged at the second input connection whereby the first signal level is present at the output terminal when the picture signal portion of the composite video signal is present at the first input connection of the synchronizing pulse comparator means and the second signal level is present at the output terminal when synchronizing pulses of the composite video signal are present at the first input connection of the synchronizing pulse comparator means.

Claim 13

Video signal processing apparatus in accordance with claim 10 wherein: said switching circuit means is operable when in a first conduction condition to permit the composite video signal to be produced at the first and second output connections of the isolation circuit means and is operable when in a second conduction condition to prevent the composite video signal from being produced at the first and second output connections of the isolation circuit means; and including: means for normally biasing the switching means to the first conduction condition; and circuit means connecting the output connection of the noise comparator means to the switching circuit means, said circuit means being operable to bias the switching means to the second conduction condition in response to the predetermined signal condition being present at the output connection of the noise comparator means and being operable to restore the switching circuit means to the normally biased first conduction condition a predetermined period of time after the predetermined signal condition appears at the output connection of the noise comparator means, said predetermined period of time being less than the period of time of each set of vertical synchronizing pulses of the composite video signal.

Claim 14

VidEo signal processing apparatus in accordance with claim 11 wherein: said noise comparator means includes a second differential amplifier circuit means having a first conduction condition and a second conduction condition, said second differential amplifier circuit means being operable to produce a first voltage level at the output connection of the noise comparator means when in the first conduction condition and being operable to produce a second voltage level at the output connection of the noise comparator means when in the second conduction condition, and means connecting the input circuit means to the first input connection of the noise comparator means and the storage capacitance to the second input connection of the noise comparator means and being operable to bias the second differential amplifier circuit means to the first conduction condition when the voltage of the composite video signal at the first input connection of the noise comparator means is less than the voltage of the synchronizing pulses to which the storage capacitance is charged at the second input connection of the noise comparator means, and being operable to bias the second differential amplifier circuit means to the second conduction condition when the voltage at the first input connection of the noise comparator means is greater by a predetermined amount than the voltage of the synchronizing pulses to which the storage capacitance is charged at the second input connection of the noise comparator means whereby the second voltage level is present at the output connection of the noise comparator means when noise having a voltage greater than the voltage of the synchronizing pulses is present in the composite video signal; said circuit means connecting the output connection of the noise comparator means to the switching circuit means includes a resistance-capacitance arrangement operable to bias the switching circuit means to the second conduction condition when the voltage at the output connection of the noise comparator means changes from the first voltage level to the second voltage level and to maintain the switching circuit means in the second conduction condition until the capacitance of the resistance-capacitance arrangement charges to a predetermined value, the capacitance of the arrangement charging to the predetermined value said predetermined period of time after the voltage at the output connection of the noise comparator means changes from the first voltage level to the second voltage level; and said noise comparator means also includes means connected to the output connection of the noise comparator means and operable to discharge the capacitance of the resistance-capacitance arrangement when the voltage at the output connection changes from the second voltage level to the first voltage level.

Claim 15

Video signal processing apparatus in accordance with claim 12 wherein said input circuit means includes: a differential amplifier circuit means having an input connection for applying detected composite video signals thereto and being operable to produce amplified composite video signals at the input connection of the isolation circuit means and at the first input connection of the noise comparator means.