Colour television display apparatus

Claim 2

A circuit comprising input means for receiving a color information signal having an alternating characteristic from line to line and a line frequency synchronization signal, a first change-over switching means coupled to said input means to receive at least a portion of said color signal for compensating for said alternating characteristic, a generator having an input means for receiving only a line frequency signal, and an output means coupled to said switching means for control of the switching state of said switching means without regard to phase ambiguity between the state of the alternating characteristic and the state of said switching means, and means coupled to said switching means for correcting the results of any of said phase ambiguity without affecting the state of said switching means.

Claim 3

A circuit as claimed in claim 1 wherein said color information signal comprises a line frequency alternating phase color burst subcarrier and two color component signals, one of said components having a line frequency alternating phase said correcting means comprising frequency gated gate means coupled to said input means for providing said color burst, a first phase discriminator coupled to said gate, a subcarrier regenerator coupled to said discriminator, first and second synchronous demodulator means coupled to input means for demodulating said alternating and remaining component signals respectively, said first demodulator being coupled to said switching means for receiving said burst signal, a second phase discriminator coupled to said regenerator and said gate, and a second change-over switching means coupled to said second discriminator for control thereof.

Claim 4

A circuit as claimed in claim 2 wherein said first switching means comprises an output coupled to an input of one of said discriminators, and two inputs, one of said inputs being coupled to said regenerator, and further comprising means coupled between said remaining input and said regenerator for providing a 180.degree. phase shift.

Claim 5

A circuit as claimed in claim 2 wherein said first switching means comprises an output directly connected to an input of said first discriminator, and two inputs; said second switching means comprising two inputs coupled to said first switching means inputs respectively, and an output coupled to said second demodulator; a 90.degree. phase shifting network coupled between said first switching means output and said first demodulator, and said second discriminator being directly connected to said regenerator.

Claim 6

A circuit as claimed in claim 2 wherein the regenerator output is directly connected to said first discriminator, and further comprising a 90.degree. phase shift network coupled between said regenerator and said second demodulator, said first switching means having an output directly connected to said second phase discriminator, said second switching means having a first input directly coupled to said first switching means output, a second input, and an output directly connected to said first demodulator andn means for providing a 180.degree. phase shift coupled between said first switching means output and said second switching means second input.

Claim 7

A circuit as claimed in claim 2 wherein said first switching means comprises a pair of inputs coupled to said input means to receive said component and burst signals, and an output coupled to said first demodulator, said gate being coupled between said first switching means output and said first discriminator; said regenerator being directly connected to said first discriminator and to said second modulator; a 90.degree. phase shift network coupled between said regenerator and to said first demodulator; a second gate coupled between one of said first switching means inputs and said second discriminator; said second discriminator having an input coupled to said first discriminator and an output coupled to control said second switching means, and said second switching means having a pair of inputs coupled to said first switching means inputs respectively, and an output coupled to said second demodulator.

Claim 8

A circuit as claimed in claim 2 wherein said first switching means comprises a first input coupled to said input means for receiving said component and burst signals, a second input, and an output; a first 180.degree. phase shifting means coupled between said input means and said second input; a second line frequency keyed gate coupled between said output and said second discriminator; said second switching means having a first input coupled to said output, a second input, and an output coupled to said first demodulator; a second 180.degree. phase shifting means coupled between said first switching means output and said second switching means second input; said regenerator being coupled to said second discriminator and to said first demodulator; and a 90 degree phase shifting means coupled between said regenerator and said second demodulator.

Claim 9

A circuit as claimed in claim 1 said correcting means comprising an identification signal means coupled to said input means for supplying a burst signal of one half the line frequency, a half line frequency phase detector having inputs coupled to said identification means and to said change-over generator respectively, and a correction second change-over switching means having a control input coupled to said half line frequency phase detector.

Claim 10

A circuit as claimed in claim 8 wherein said second switching means comprises a phase change-over switch coupled to said change-over signal generator.

Claim 11

A circuit as claimed in claim 8 further comprising a color demodulator having an input and wherein said color signal comprises a PAL signal and said second switching means comprises a phase switching means coupled to said demodulator input.

Claim 12

A circuit as claimed in claim 1 wherein said color signal comprises a PAL signal, said correcting means comprising first and second synchronous demodulators coupled to said input circuit, first and second subcarrier regenerators coupled to said demodulators respectively, and said change-over switching means comprising a first phase switching means independnet of identification signals coupled between said input means and said second demodulator.

Claim 13

A circuit as claimed in claim 11 further comprising a second phase switching means switching in accordance with said first phase switching means and coupled between said input means and said second regenerator.