JPH06205437A - Magnetic recording and reproducing device and video signal reproducing device - Google Patents

Abstract

PURPOSE:To prevent inversion of a chrominance signal and an audio signal due to a recording level of a low frequency portion of them and to prevent production of audio noise in the magnetic recording and reproducing device having 4-channel magnetic heads. CONSTITUTION:Four video signal use magnetic heads 3 are used to convert a chrominance signal into a low frequency portion of a luminance signal and to record the converted signal onto a magnetic recording medium 4 and the heads 3 are used to record an FM modulation audio signal at an intermediate band between the chrominance signal and the luminance signal onto the recording medium. Furthermore, a re-adjustment means 5 adjusts again a level of a recording current of a low frequency signal of the chrominance signal and the audio signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus and a video signal reproducing apparatus capable of obtaining a stable reproduced image.

[0002]

2. Description of the Related Art Conventionally, there is known a magnetic recording / reproducing apparatus which has four magnetic heads for video signals and records the video signals on a magnetic tape for each channel. When reproducing a video signal recorded on this magnetic tape, for example, a reproduction color signal processing circuit is provided with a two-channel ACC (automatic col).
or control) so that the reproduced image does not cause color flicker even when it is reproduced by a reproducing device having a circuit.
The color signal recording current is adjusted so that the color signal recording levels of the paired magnetic heads are the same.

Further, a conventional video signal reproducing apparatus reproduces a video signal by reading a recorded signal from a magnetic tape, demodulating it, and then performing de-emphasis processing. At this time, if the characteristics of the recorded signal or the reproduction pulse at the time of reproduction are improved, the underpulse of the luminance signal may drop to near the level of the synchronization signal.

[0004]

However, in the conventional magnetic recording / reproducing apparatus as described above, since the adjusting method is such that the level difference of the recorded color signals is always zero, the recording sensitivity is high. When the magnetic heads that are greatly different from each other are paired, the recording current of the color signal including the AFM signal (audio FM signal) largely deviates from the preset value, and the following problems occur.

(I) When the recording current of the low-frequency signal (color signal + AFM signal) becomes too large, the recording saturation level of the luminance signal decreases, or the AFM adjacent to the luminance signal band.
Since the recording level of the signal increases, inversion easily occurs.

(Ii) If the recording current of the low frequency signal becomes too small, the AFM signal is disturbed by the luminance signal, and voice noise is generated.

Further, in the conventional video signal reproducing apparatus, the undershoot pulse of the luminance signal drops to a level near the synchronizing signal due to the characteristics improvement of the signal recorded as described above and the pulse signal at the time of reproduction. In this case, there is a problem in that the monitor may erroneously determine the undershoot pulse as a synchronization signal, causing an H (horizontal) tension or a V (vertical) deviation.

The present invention has been made by paying attention to the above-mentioned problems, and prevents magnetic signal inversion and audio noise from occurring, and magnetic recording / reproducing in which a stable reproduced image can be obtained. We also provide equipment, H tension and V
It is an object of the present invention to provide a video signal reproducing device which can obtain a stable reproduced image without any deviation.

[0009]

The magnetic recording / reproducing apparatus of the present invention is configured as follows.

(1) Four magnetic heads for recording and reproducing are provided, and a color signal is converted into a low range of a luminance signal and recorded on a magnetic recording medium, and a recording current of the color signal is recorded as an audio signal. An adjusting means for adjusting with the current is provided.

(2) Four magnetic heads for recording and reproducing are provided, and a color signal is converted into a low band of a luminance signal and recorded on a magnetic recording medium, and an audio signal is banded and luminance of the color signal. Recording is performed during the signal band, and this audio signal is also recorded / reproduced by the magnetic head together with the video signal, and an adjusting means for adjusting the recording current of the color signal together with the recording current of the audio signal is provided.

Further, the video signal reproducing apparatus of the present invention is provided with a control means for performing dark clip processing on the reproduction luminance signal.

[0013]

In the magnetic recording / reproducing apparatus of the present invention, the set value for readjustment of the recording current of the color signal is set to have a certain difference, for example, the recording level difference of the color signal of the bearing magnetic head, rather than zero. By setting the readjustment value to have an upper limit and a lower limit, the low frequency recording current can be suppressed within a certain range.

Further, in the video signal reproducing apparatus of the present invention, by providing means for applying a dark clip to the luminance signal after the reproduction signal processing, even if the pulse characteristic is increased for improving the image quality, the video signal is synchronized with the sync signal level. It is possible to prevent H tension and V deviation due to erroneous determination of the monitor synchronization signal.

[0015]

1 is a block diagram showing the essential parts of a magnetic recording / reproducing apparatus according to an embodiment of the present invention. In the figure, 1
Is a signal processing circuit that performs FM modulation processing, etc., and outputs a Y signal (luminance signal), a C signal (color signal), and an AF signal.
The M signal (voice modulation signal) is input to the amplifier circuit 2. Three
Is a recording / reproducing magnetic head, 4 is a magnetic recording medium,
Reference numeral 5 is a readjusting means for readjusting the recording current of the C signal together with the recording current of the AFM signal.

On the magnetic recording medium 4, the C signal is converted into the low frequency band of the Y signal and recorded, and the AFM signal is recorded between the band of the C signal and the band of the Y signal, and this AFM is recorded. The signal is recorded and reproduced together with the video signal by the magnetic head 3 for the video signal.

Further, the readjustment means 5 makes the set value for readjustment of the recording current of the C signal to have a certain difference in the recording level difference of the paired magnetic heads 3 instead of zero. By controlling the adjustment value to have an upper limit and a lower limit, the low frequency recording current is controlled to be within a certain range.

FIG. 2 is a flow chart showing the readjustment operation in the circuit of FIG. First, in step S1, a test signal is recorded, and a track on the magnetic recording medium 4 recorded by the magnetic heads 3 of channels CH1 and CH3 is recorded on the track C.
The color signal level reproduced on H1 and the track recorded on CH2 and CH4 was reproduced on CH2 by Vc for each channel.
1, Vc2, Vc3 and Vc4. Next, step S
2. Adjusting standard value with | Vc1 / Vc3 | ≦ X [dB], | V
If c2 / Vc3 | ≦ X [dB] is not satisfied, the recording current of the C signal is readjusted in step S3.

Here, the recording currents of the color signals of the respective channels at the preset time are set to RecC1, RecC2, RecC.
3, RecC4, RecC1 ', Rec after readjustment
If C2 ′, RecC3 ′, RecC4 ′, then RecC1 ′ = α1 ′ + RecC1 [dB] α1 = (Vc1 + Vc3) / 2Vc1 RecC2 ′ = α2 ′ + RecC2 [dB] α2 = (Vc2 + Vc4) / 2Vc2 RecC3Re = C3Re = C3Re = α3 ′ dB] α3 = (Vc1 + Vc3) / 2Vc3 RecC4 '= α4' + RecC4 [dB] α4 = (Vc2 + Vc4) / 2Vc4.

However, the relationship between αi and αi 'is as follows. That is, | Vc1 / Vc3 | = | V after readjustment
c2 / Vc4 | = 2Z (0 <Z ≦ X / 2), and the readjustment value αi ′ (i = 1, 2, 3, 4) is set to | αi ′.
If a limit value of | ≦ Y is set, αi ′ = − Y− (Y + Z) <αi <−X if αi ≦ − (Y + Z), αi ′ = αi + Z −X ≦ αi ≦ X, αi ′ = 0 If X <αi <Y + Z, then αi ′ = αi−Z Y + Z ≦ αi, then αi ′ = Y.

By re-adjusting the recording level of the low frequency signal as described above, it is possible to prevent the above-mentioned inversion and also to prevent the occurrence of voice noise.

FIG. 3 is a block diagram showing the configuration of another embodiment of the present invention, showing the main part of the video signal reproducing apparatus. In the figure, 6 is a reproduction processing circuit for reproducing and outputting a Y signal (luminance signal) from a magnetic recording medium, and 7 is a reproduction Y thereof.
A gate circuit for extracting a synchronization (SYNC) signal from the signal, and the gate signal is input to the controller 8. 9
Is a slicer provided as control means for performing dark clip processing on the reproduced Y signal, and 10 is an output circuit.

In the reproducing apparatus having the above structure,
By demodulating and de-emphasis during reproduction, and subjecting the reproduced video Y signal that has been signal processed to a sync signal, and slicing using a control signal at a timing such as slicing only the video signal, The undershoot allows the monitor to output a reproduced video signal that does not cause the sync signal to be erroneously determined.

That is, by applying a dark clip to the reproduced video Y signal, it is possible to prevent the monitor from causing an H-sync erroneous determination due to an underpulse of the Y signal and causing an H tension or V deviation, which is stable. The reproduced image can be obtained.

FIG. 4 shows the output waveforms of the respective parts a and b in FIG. 3, where (a) shows the Y signal before dark clip processing and (b) shows the Y signal after dark clip processing. ing.

As a method capable of enhancing the effect equivalent to that of this embodiment, for example, a dark clip may be applied to a signal by inserting a sync signal after applying a dark clip at the pedestal level of a reproduced video signal. it can. Further, the reproduced video luminance signal may be digitally converted, and data conversion may be performed so as to obtain the same effect.

[0027]

As described above, according to the present invention, the color signal is converted into the low range of the luminance signal and recorded, and the recording current of the color signal can be readjusted together with the audio signal. There is an effect that the occurrence of inversion can be prevented, an occurrence of voice noise can be prevented, and a stable reproduced image can be obtained.

Further, according to the present invention, since the reproduction luminance signal can be subjected to the dark clip processing, erroneous determination of the synchronizing signal on the monitor is eliminated, and there is no H tension or V deviation.
There is an effect that a stable reproduced image can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the circuit of FIG.

FIG. 3 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 4 is an output waveform diagram of each part in FIG.

[Explanation of symbols]

 3 magnetic head 4 magnetic recording medium 5 readjustment means 9 slicer (control means)

Claims (3)

[Claims] 1. A recording / reproducing magnetic head is provided,
A magnetic recording / reproducing apparatus characterized in that a color signal is converted into a low range of a luminance signal and recorded on a magnetic recording medium, and an adjusting means for adjusting a recording current of the color signal together with a recording current of an audio signal is provided. . 2. A magnetic recording head having four recording and reproducing heads,
On the magnetic recording medium, the color signal is converted into the low band of the luminance signal and recorded, and the audio signal is recorded between the band of the color signal and the band of the luminance signal. A magnetic recording / reproducing apparatus comprising an adjusting means for recording / reproducing by a head and adjusting a recording current of the color signal together with a recording current of an audio signal. 3. A video signal reproducing apparatus comprising a control means for performing dark clip processing on a reproduction luminance signal.