JPH03198487A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent a signal pattern, which is peculiar for a signal excepting for a video signal and hard to be observed, from being reproduced by discriminating whether a signal recorded to a magnetic recording medium is the video signal or not, and reproducing only the video signal. CONSTITUTION:A video synchronizing counter 8 counts a synchronizing pulse outputted from a signal separator circuit 7 which separates the synchronizing pulse from the output of a video signal processing circuit 5. When the count value is from 262 to 282, the reproduced signal is discriminated as the video signal, an output permit signal is inputted to a video output circuit 6 and reproducing is permitted. Thus, since the video signal can be discriminated by counting the number of the synchronizing pulses outputted from the signal separator circuit 7 and only the video signal can be reproduced, the signal pattern, which is peculiar for the signal excepting for the video signal and hard to be observed, can be prevented from being reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording and reproducing device that determines that a signal to be reproduced is a video signal and reproduces only the video signal. An example of a recording and reproducing apparatus will be explained based on the block diagram of a video floppy reproducing apparatus shown in FIG.

A conventional floppy playback device includes a magnetic head 2 that picks up a signal recorded on a video floppy 1, a playback amplification circuit 3 that amplifies the FM signal picked up by the magnetic head 2, and an FM demodulation of the FM signal amplified by the playback amplification circuit 3. F bl demodulation circuit 4° Video signal processing circuit that performs video signal processing of the FM demodulated signal 5. and a video output circuit 6 that outputs the video signal processed by the video signal processing circuit 5.

The operation of the conventional video floppy playback device will be described below.

When playing back signals recorded on a video floppy disk,
Transfer the signal recorded on video floppy 1 to 1a head 2.
The picked-up FM signal is amplified by a regenerative amplifier circuit 3, demodulated by an FM demodulation circuit 4, processed by a video signal processing circuit 5, and outputted by a video output circuit 6 to a TV monitor, video printer, etc. Connect and play.

Problems to be Solved by the Invention However, in the configuration described in T, video floppy l
When playing back the signal recorded on the video floppy 1
When the recorded signal is a signal other than a video signal, for example an audio signal, there is a problem in that when the signal is reproduced on a television monitor, a signal pattern peculiar to the audio signal is reproduced, making it very unsightly.

The present invention has been made to solve the above problem, and aims to provide a magnetic recording/reproducing device that prevents the reproduction of unique signal patterns other than video signals.

Means for Solving the Problems In order to solve the problems, the magnetic recording and reproducing apparatus of the present invention has the following features:
The apparatus includes a reproducing means for reproducing a signal recorded on a magnetic recording medium, and a video signal determining means for determining whether the output signal of the reproducing means is a video signal.

A second invention provides the video signal discriminating means of the first invention described in F,
A signal separation means for separating a synchronization pulse from an output signal of the reproduction means, and determining whether the output signal of the reproduction means is a video signal by determining whether or not the synchronization pulse separated by the signal separation means is a video synchronization pulse. A third invention comprises a determining means for determining whether or not the signal is rejected, and a third invention is characterized in that the determining means of the second invention includes a counting time for setting a time for counting the number of synchronizing pulses separated by the signal separation means. counting the number of synchronous pulses of the signal separating means during the time set by the setting means and the counting time setting means, and if the counted value is within a predetermined value, the synchronous pulse of the signal separating means is imaged. It consists of a counting means for distinguishing it from a synchronous pulse. Further, a fourth invention provides a first counting means for counting the time width of the synchronizing pulses separated by the signal separation means and outputting only the synchronizing pulses having a predetermined time width. , counting time setting means for setting a time for counting the number of synchronous pulses of the signal separation means, and counting the number of output pulses of the first counting means during the time set by the counting time setting means. , if the count value is within the predetermined value.

The second counting means distinguishes the synchronizing pulse of the signal separation means from the video synchronizing pulse.

According to the configuration of the first aspect of the invention, when a signal recorded on a magnetic recording medium is reproduced, it is determined whether the reproduced signal is a video signal or not, and it becomes possible to reproduce and output only the video signal.

Further, according to the configuration of the second invention, the synchronization pulse separated from the reproduction signal by the signal separation means is determined to be a video synchronization pulse, whereby the reproduction signal is determined to be a video signal. Due to the configuration of the number of synchronization pulses of the signal separation means.

Alternatively, the number of synchronization pulses selected by the pulse time width is counted during a set time, and if the counted value is within a predetermined value, the synchronization pulse of the signal separation means is determined to be a video synchronization pulse.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings. It should be noted that the same components as those of the conventional example shown in FIG.

FIG. 1 is a block diagram of a video floppy playback device showing an embodiment of the present invention.

The video floppy device of the present invention differs from the conventional regenerative amplifier circuit 3. FM demodulation circuit 4. The video signal processing circuit 5 and the video output circuit 6 are newly provided with a signal separation circuit 7 that separates a synchronization pulse from the output signal of the video signal processing circuit 5, and a signal separation circuit 7.
A synchronous pulse counter that counts the number of synchronous pulses separated by , and when the count value becomes the same from 262 to 282, it determines that the reproduced signal is a video signal and outputs a permission signal to permit the output of the video output circuit 6. 8 and a count time setting circuit 9 for setting the time counted by the synchronous pulse counter 8 to one vertical synchronization period.

In addition, the number of pulses to be determined as a video signal is set from 262 to 282.
The reason for this is that the normal number of video synchronization pulses is 272 (NTSC system) within one vertical synchronization period, and when a noisy video signal is input to the signal separation circuit 7, the signal separation circuit 7 Since pulses in the noise part of the output may occur and the video signal may be misjudged as not being a video signal, the limit is set to 282 with a margin, and when a normal audio signal is played back, the signal separation circuit The number of output pulses of 7 is several times as large as when reproducing a video signal, but if there are many silent parts in one track, there is a possibility that the number of output pulses will be less than when reproducing a video signal, so the lower limit was set to 262.

The operation of the video floppy playback device having the configuration described in E will be explained.

The synchronization pulse output from the signal separation circuit 7.

The video synchronization pulse counter 10 counts and when the count value is between 262 and 282, the reproduced signal is determined to be a video signal and an output permission signal is input to the video output circuit 6I to permit reproduction.

In this way, by counting the number of output synchronization pulses of the signal separation circuit 7, it is possible to distinguish the video signal, and only the video signal can be reproduced, thereby preventing the reproduction of unsightly signal patterns peculiar to signals other than video signals. be able to. Furthermore, the discrimination accuracy can be improved compared to detecting a video signal from an analog playback signal, and the circuit can be simplified.

Another embodiment of the present invention will be described based on the block diagram of a video floppy playback device shown in FIG.

Note that the same components as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

The video floppy playback device shown in FIG. 2 counts the time width of the synchronization pulses output from the signal separation circuit 7,
A pulse time counter 10 is provided that outputs only pulses within a period of 4 μsec to 6 μsec.

The video synchronous pulse counter 8 is configured to count the output pulses of the pulse time counter 10. 4μs
By extracting a pulse with a period of 6 μsec from ec, the output of the signal separation circuit 10 is inhibited when an audio signal is reproduced, and only the horizontal synchronizing pulse is extracted, thereby preventing misjudgment due to noise.

The operation of the video floppy playback apparatus shown in FIG. 2 will be explained below.

The time width of the synchronization pulse output from the signal separation circuit 7 is counted by the pulse time counter 10, and the time width is counted from 4 μSec to 6
Output only pulses with a period of μSec and count them with the video synchronization pulse counter 10, and the count value will be between 262 and 282.
If the reproduced signal is determined to be a video signal, an output permission signal is input to the video output circuit 6 to permit reproduction.

In this way, it is possible to prevent misjudgment of the video signal due to noise that is output from the signal separation circuit 7 within the time set by the count time setting circuit 9.

Discrimination accuracy can be improved.

Effects of the Invention As described above, according to the first invention, by determining whether the signal recorded on the magnetic recording medium is a video signal, it is possible to reproduce only the video signal, and it is possible to reproduce signals other than the video signal, For example, when an audio signal is reproduced, it is possible to prevent unsightly signal patterns peculiar to the audio signal from being reproduced.

Further, according to the second invention, by determining whether or not the synchronizing pulse of the signal separation means is a video synchronizing pulse, it is possible to obtain an effect that the determination accuracy is better than that of detecting a video signal from an analog playback signal. I can do it.

Furthermore, according to the third invention, the circuit can be greatly simplified by counting the number of synchronizing pulses of the signal separating means, and according to the fourth invention, the time width of the synchronizing pulse of the signal separating means By counting , it is possible to obtain the effect of further improving the discrimination accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a video floppy playback device showing an embodiment of the magnetic recording and playback device of the present invention. FIG. 2 is a block diagram of a video floppy playback device showing another embodiment of the magnetic recording and playback device of the present invention. FIG. 3 is a block diagram of a conventional video floppy playback device. 1...Video floppy, 2...Magnetic head, 3.
... Regenerative amplifier circuit, 4... FM demodulation circuit, 5... Video signal processing circuit, 6... Video output circuit, 7... Signal separation circuit %8... Video synchronization pulse counter, 9.・
・Count time setting circuit, 10.--Pulse time counter.

Claims (1)

[Scope of Claims] 1. A magnetic recording and reproducing apparatus comprising a reproducing means for reproducing a signal recorded on a magnetic recording medium, and a video signal determining means for determining whether an output signal of the reproducing means is a video signal. 2. The video signal discriminating means includes a signal separating means for separating the synchronizing pulse from the output signal of the reproducing means, and a signal separating means for separating the synchronizing pulse from the output signal of the reproducing means by determining whether or not the synchronizing pulse separated by the signal separating means is a video synchronizing pulse. 2. The magnetic recording and reproducing apparatus according to claim 1, further comprising determining means for determining whether the output signal is a video signal. 3. The determination means includes a counting time setting means for setting a time for counting the number of synchronization pulses separated by the signal separation means, and a counting time setting means for setting the time for counting the number of synchronization pulses separated by the signal separation means, and a count time setting means for setting the time for counting the number of synchronization pulses separated by the signal separation means, and a count time setting means for setting the time for counting the number of synchronization pulses separated by the signal separation means, and a count time setting means for setting the number of synchronization pulses of the signal separation means during the time set by the counting time setting means. 3. The magnetic recording and reproducing apparatus according to claim 2, further comprising a counting means for counting the number of signals and determining the synchronizing pulse of the signal separating means as a video synchronizing pulse if the counted value is within a predetermined value. 4. The determination means includes a first counting means that counts the time width of the synchronization pulses separated by the signal separation means and outputs only synchronization pulses with a predetermined time width; a counting time setting means for setting the counting time;
The number of output pulses of the first counting means during the time set by the counting time setting means is counted, and if the counted value is within a predetermined value, the synchronization pulse of the signal separation means is set as the video synchronization pulse. 3. The magnetic recording and reproducing apparatus according to claim 2, further comprising second counting means for determining.