Video signal recording and reproducing apparatus including a noise reduction circuit

Claim 1

A video signal recording and reproducing apparatus including a noise reduction circuit, said apparatus comprising: a frequency modulator for frequency-modulating a recording video signal which is to be recorded; recording means for recording an output frequency modulated recording video signal of said frequency modulator onto a recording medium; demodulating means including first means for reproducing the recorded frequency modulated video signal from the recording medium and second means for demodulating the reproduced frequency modulated video signal back into the original video signal; a noise reduction circuit for reducing a noise component in the output reproduced video signal of said demodulating means by pre-emphasizing portions of the video signal at the time of the recording and correspondingly de-emphasizing the pre-emphasized video signal portions at the time of the reproduction, said noise reduction circuit comprising a first delay circuit having a delay time of one horizontal scanning period for producing a delayed reproduced video signal from an output video signal of said first or second means of said demodulating means, a first differential amplifier supplied directly with the output reproduced video signal of said demodulating means and with the output delayed reproduced video signal of said first delay circuit, a first limiter for amplitude-limiting an output signal of said first differential amplifier, and a subtracting circuit for performing a subtraction between the output reproduced video signal of said demodulating means and an output signal of said first limiter; a second differential amplifier supplied directly with said recording video signal to one input terminal thereof; a second delay circuit for delaying said recording video signal by a delay time of one horizontal scanning period, and for supplying a delayed recording video signal to another input terminal of said second differential amplifier; a second limiter for amplitude-limiting an output video signal component of said second differential amplifier, to a limiting level which is approximately in the same range as a limiting level of said first limiter; an adding circuit for adding an output limited video signal component of said second limiter to said recording video signal, a common differential amplifier being used as said first and second differential amplifiers, a common delay circuit being used as said first and second delay circuits, a common limiter being used as said first and second limiters; and circuit means for selectively supplying the output limited video signal component of said common limiter to said subtracting circuit with the phase thereof inverted at the time of the recording, and for selectively supplying the output signal of said common limiter to said subtracting circuit with the phase thereof unchanged at the time of the reproduction, so that said subtracting circuit can also be used as said adding circuit.