JPS6373785A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To suppress the width of band noise generated at the time of a specific reproduction such as a fast forward reproduction, a still reproduction small and to execute a good reproduction by setting the detecting sensitivity of a drop out detector higher that at the time of an ordinary reproduction. CONSTITUTION:A sensitivity setting device 4 varies the detecting sensitivity of the drop out detector 1 and sets the detecting sensitivity at the time of the fast forward reproducing higher than that at the time of the ordinary reproduction. When the reproduced output of a video enters the detector 1 and the generation of the drop out is detected, a switch circuit 3 is switched by a pulse signal outputted from the detector 1, a video signal delaying by one horizontal synchronizing period by a delay circuit 2 is outputted and a deficient part is compensated. At the time of the fast forward reproducing, the detecting sensitivity of the detector is high, so that a period when the band noise generated in the joint part of an ordinary reproduced signal and a drop out compensating signal is buried by a reproduced signal grows longer and the width of the band noise is suppressed small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Applicability "rf] The present invention relates to a magnetic recording and reproducing apparatus having a circuit for compensating for dropout of a reproduced signal such as a reproduced video signal.

[Prior Art] FIG. 2 is a block diagram of a dropout compensation circuit in a conventional magnetic recording/reproducing device. In the figure, (1) is a detector that detects the occurrence of dropout in the reproduced signal;
2) is a delay circuit that delays the reproduced signal by one horizontal opening period;
(3) is a signal changeover switch circuit.

Next, the operation of the above configuration will be explained.

The reproduced output of the frequency modulated signal enters the dropout detector (1), and if no dropout is detected, it is output from the switch circuit (3). When the occurrence of dropout is detected, this detector (+)
The pulse signal output from the switch circuit (3) switches, and the playback signal delayed by the delay circuit (2) by one water period is transferred to the switch circuit (3).
3) is output. Therefore, the missing part of the reproduced signal is
It is compensated by the belief one horizontal opening period ago.

[Problem to be Solved by the Invention 1] In the conventional magnetic recording/reproducing device configured as described above, dropout compensation is performed using a frequency-modulated signal. This has the drawback that band-shaped noise and other disturbances occur at the joint with the signal for out-compensation, making it visually very difficult to see, especially in the case of video signals.

Particularly, during special playback such as fast-forward playback and still playback, there is a problem in that the width of the band-shaped noise is increased.

The present invention has been made to solve these problems, and an object of the present invention is to provide a magnetic recording and reproducing apparatus that can perform good reproduction by suppressing the width of band-shaped noise generated during reproduction.

[Means for Solving the Problems] The magnetic recording and reproducing apparatus according to the present invention is characterized in that a sensitivity setting device is provided for varying the detection sensitivity of the dropout detector in the dropout compensation circuit.

[Function] In the present invention, by setting the detection sensitivity of the dropout detector to be higher than that during normal playback without occurrence of dropout using the sensitivity setting device,
The period during which the band-like noise generated when dropout is detected during playback is embedded in the reproduced signal becomes longer, and therefore the width of the band-like noise becomes smaller.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram of a dropout compensation circuit in a magnetic recording/reproducing apparatus according to an embodiment of the present invention. In the figure, (1), (2), and (3) are the same components as the conventional dropout compensation circuit shown in FIG. 2, so detailed explanation thereof will be omitted.

In Fig. 1, (4) is a sensitivity setting device, which makes the detection sensitivity of the dropout detector (1) variable, and sets the detection sensitivity during fast-forward playback to be larger than during normal playback. . Specifically, the voltage applied to a terminal (not shown) is increased.

(5) is a demodulator, which demodulates the frequency modulated video signal.

Next, the operation of the dropout compensation circuit having the above configuration will be explained.

The frequency modulated video playback output enters a dropout detector (1). Here, if the occurrence of dropout is not detected, the video signal is demodulated by the demodulator (5) and output via the switch circuit (3).

When the detector (1) detects the occurrence of dropout, the pulse signal generated and output by the detector (1) is sent to the switch circuit (3). ): Switched to JSiSi line and dotted line. By this, ′j! l by extension circuit (2)
The video signal delayed by the horizontal synchronization period is outputted via the switch circuit (3), and the missing portion is compensated for by the video signal from 1*before the synchronization period.

In such a dropout compensation operation, during fast-forward playback, the dropout detection sensitivity of the detector (1) is high, so band noise generated at the joint between the normal playback signal and the signal for dropout compensation or the playback The period embedded by the signal becomes larger, and the width of band-like noise is suppressed to a smaller value.

In addition, in this embodiment, since the video signal delayed by the delay circuit is a signal demodulated by the demodulator (5), there is little attenuation even by multiple eel-back delay operations, and therefore, It is possible to make the band noise compensation period sufficiently long.

In addition, in the above embodiment, the above detector (1
), the same effect can be expected in other cases, for example, during pause 1: playback, so-called still playback.

[Effects of the Invention] As described above, according to the present invention, by setting the detection sensitivity of the dropout detector to a large value, it is possible to reduce the width of band-like noise generated in the dropout compensation operation. This makes it possible to make the noise bar visually very easy to see, especially during special playback such as fast-forward playback and still playback.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a dropout compensation circuit in a magnetic recording and reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of a dropout compensation circuit in a conventional magnetic recording and reproducing apparatus. (1)...dropout detector, (2)...delay circuit, (3)...changeover switch circuit, (4)...sensitivity setter, (5)...demodulator. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A detector that detects the occurrence of dropout in the reproduced signal, a delay circuit that delays the reproduced signal by one horizontal synchronization period, and when the detector detects the occurrence of dropout,
In a magnetic recording/reproducing device having a dropout compensation circuit including a switch circuit configured to output a reproduced signal delayed by one horizontal synchronization period by the delay circuit, the detection sensitivity of the dropout detector is made variable. A magnetic recording and reproducing device characterized by being provided with a sensitivity setting device. (2) The magnetic recording and reproducing apparatus according to claim 1, further comprising a demodulator that demodulates the reproduced signal.