Video tape reproducing apparatus capable of preventing influence of noise-bar

A video tape reproducing apparatus comprising:

• drop-out detection circuit for detecting a drop out generated in a low-frequency carrier wave FM signal contained in a reproduced signal when a video tape is reproduced in a special mode, wherein
• said drop-out detection circuit comprises:
• an envelope reduction detection circuit which detects a period in which the envelope of the low-frequency carrier wave FM signal is smaller than a predetermined amplitude so as to output a pulse signal;
• and
• a pulse-width elongation circuit for elongating the trailing edge of the pulse signal output from said envelope reduction detection circuit, said pulse-width elongation circuit being structured such that when a next pulse signal is supplied from said envelope reduction detection circuit in a period in which said pulse-width elongation circuit is elongated the trailing edge of the pulse, said pulse-width elongation circuit elongates the pulse width by using the trailing edge of the new pulse signal;
• a noise-bar period detection circuit for detecting a period of a noise bar in response to an output signal from said drop-out detection circuit so as to output a noise-bar detection signal;
• and
• at least one reproduced-signal processing circuit which is controlled in the period of the noise bar in response to the noise-bar detection signal output from said noise-bar period detection circuit.

A video tape reproducing apparatus comprising:

• a drop-out detection circuit for detecting drop out generated in a low-frequency carrier wave FM signal contained in a reproduced signal when a video tape is reproduced in a special mode,
• said drop-out detection circuit comprising:
• an envelope reduction detection circuit which detects a period in which the envelope of the low-frequency carrier wave FM signal is smaller than a predetermined amplitude so as to output a pulse signal;
• and
• a pulse-width elongation circuit for elongating the trailing edge of the pulse signal output from said envelope reduction detection circuit, said pulse-width elongation circuit being structured such that when a next pulse signal is supplied from said envelope reduction detection circuit in a period in which said pulse-width elongation circuit is elongated the trailing edge of the pulse, said pulse-width elongation circuit elongates the pulse width by using the trailing edge of the new pulse signal;
• a noise-bar period detection circuit for detecting a period of a noise bar in response to an output signal from said drop-out detection circuit so as to output a noise-bar detection signal;
• at least one reproduced-signal processing circuit which is controlled in the period of the noise bar in response to the noise-bar detection signal output from said noise-bar period detection circuit;
• a demodulation circuit for demodulating the low-frequency carrier wave FM signal;
• a delay circuit for delaying signal demodulated by said demodulation circuit by one horizontal period;
• and
• a switch circuit for inserting the signal delayed by said delay circuit into a portion in which the drop out has been generated in response to an output signal from said drop-out detection circuit.

A signal processing circuit for processing a reproduced signal reproduced from a video tape, comprising:

• a drop-out detection circuit configured to detect drop out of the low-frequency carrier wave FM signal contained in the reproduced signal, said drop-out detection circuit outputting a drop-out detection signal in response to the drop out, wherein said drop-out detection circuit comprising:
• an envelope reduction detection circuit configured to detect a period in which the envelope of the low-frequency carrier wave FM signal contained in the reproduced signal is smaller than a predetermined amplitude so as to output a pulse signal;
• and
• a pulse-width elongation circuit configured to elongate the trailing edge of the pulse signal output from said envelope reduction detection circuit by one horizontal period or more, said pulse-width elongation circuit being structured such that when a next pulse signal is supplied from said envelope reduction detection circuit in a period in which said pulse-width elongation circuit is elongating the trailing edge of the pulse signal, said pulse-width elongation circuit elongating the pulse width by using the trailing edge of the new pulse signal as a reference so as to generate the drop-out detection signal;
• a noise-bar period detection circuit configured to detect a period of a noise bar in response to the drop-out detection signal supplied from the drop-out detection circuit, said noise-bar period detection circuit outputting a noise-bar detection signal corresponding to the period of the noise bar;
• and
• at least one reproduced-signal processing circuit controlled, in the period of the noise bar, in response to the noise-bar detection signal supplied from the noise-bar period detection circuit.