Chroma phase modulator

A chroma phase modulator comprising:

• conversion means for converting a composite video signal (Y + A sinX) to a digital signal;
• extracting means for extracting a chroma signal-A sinX from an output signal of said conversion means;
• first delay means for delaying the phase of the chroma signal-A sinX extracted by said extracting means by 90.degree. to output a chroma signal A cosX;
• second delay means for delaying the chroma signal-A sinX by a predetermined time to output a chroma signal A sinX;
• detecting means for detecting a phase modulation amount .theta. of the chroma signal A sinX extracted by said extracting means, said detecting means generating a clock signal based on the detected phase modulation amount .theta. and applying it to said conversion means;
• outputting means for outputting coefficients -(1-cos.theta.) and sin.theta. in accordance with the phase modulation amount .theta. (.theta. is any value to satisfy -.pi./2 <
• .theta. <
• .theta./2) detected by said detecting means;
• first multiplying means for multiplying the chroma signal A cosX output from said first delay means and the coefficient sin.theta. output from said outputting means;
• second multiplying means for multiplying the chroma signal A sinX output from said second delaying means and the coefficient -(1-cos.theta.) output from said outputting means;
• first adder means for adding outputs of said first and second multiplying means;
• and
• second adder means for adding an output of said first adder means and the composite video signal output from said conversion means.

A time base corrector using a chroma phase modulator comprising:

• playback means for playing a composite video signal back from a recording medium;
• conversion means for converting the composite video signal from said playback means to a digital signal;
• time base correcting means for correcting a time bas of the composite video signal from said conversion means;
• extracting means for extracting a chroma signal-A sinX from the composite video signal output from said time base corrector;
• first delay means for delaying the phase of the chroma signal-A sinX extracted by said extracting means by 90.degree. to output a chroma signal A cosX;
• second delay means for delaying the chroma signal-A sinX by a predetermined time to output a chroma signal A sinX;
• detecting means for detecting a phase modulation amount .theta. of the chroma signal-A sinX extracted by said extracting means, said detecting means generating a clock signal based on the detected phase modulation amount .theta. and applying it to said conversion means;
• outputting means for outputting coefficients -(1-cos.theta.) and sin.theta. in accordance with the phase modulation amount .theta.(.theta. is any value to satisfy -.pi./2 <
• .theta. <
• .theta./2) detected by said detecting means;
• first multiplying means for multiplying the chroma signal A cosX output from said first delay means and the coefficient sin.theta. output from said outputting means;
• second multiplying means for multiplying the chroma signal A sinX output from said second delaying means and the coefficient -(1-cos.theta.) output from said outputting means;
• first adder means for adding outputs of said first and second multiplying means;
• and
• second adder means for adding an output of said first adder means and the composite video signal output from said conversion means.

A hue control device using chroma phase modulator comprising:

• conversion means for converting a composite video signal (Y + A sinX) to a digital signal;
• extracting means for extracting a chroma signal-A sinX from an output signal of said conversion means;
• first delay means for delaying the phase of the chroma signal-A sinX extracted by said extracting means by 90.degree. to output a chroma signal A cosX;
• second delay means for delaying the chroma signal-A sinX extracted by said extracting means by a predetermined time to output a chroma signal A sinX;
• detecting means for detecting a phase modulation amount .theta. of the chroma signal-A sinX extracted by said extracting means, said detecting means generating a clock signal based on the detected phase modulation amount .theta. and applying it to said conversion means;
• outputting means for outputting coefficients -(1- cos.theta.) and sin.theta. in accordance with the phase modulation amount .theta.(.theta. is any value to satisfy -.pi./2 <
• .theta. <
• .theta./2) detected by said detecting means;
• first multiplying means for multiplying the chroma signal A cosX output from said first delay means and the coefficient sin.theta. output from said outputting means;
• second multiplying means for multiplying the chroma signal A sinX output from said second delaying means and the coefficient -(1- cos.theta.) output from said outputting means;
• first adder means for adding outputs of said first and second multiplying means;
• second adder means for adding an output of said first adder means and the composite video signal output from said conversion means;
• burst detecting means for detecting a burst signal contained in the composite video signal (Y + A sinX);
• and
• gate means for supplying a phase modulation amount .theta. to said coefficient outputting means, said gate means being disabled against the supply of the phase modulation amount to said coefficient outputting means when the burst signal is detected by said burst detecting means.