JPH0595564A - Magnetic recording and reproducing method, magnetic recording device and magnetic reproducing device - Google Patents

Abstract

PURPOSE:To correct a time base even during a 1H period in the case of recording and reproducing MUSE signals and to share those signals with the standard television signals of NTSC, PAL and SECAM or the like. CONSTITUTION:In the case of recording the MUSE signals, the pilot signals of continuous waves out of the band of the MUSE signal are added and afterwards, the frequency is modulated. Then, a prescribed synchronizing signal is added to a band lower than that of an FM signal and magnetically recorded and in the case of reproduction, these synchronizing signal and pilot signal are separated. Based on both signals, a clock signal for write is prepared, the demodulated MUSE signal is written in a buffer memory (86) used as a TBC, and time base correction is executed. Four magnetic heads (56, 58, 60 and 62) are fitted to a rotary drum having 41mm diameter at 90 deg. intervals, and the signals are shared with the standard signal of the NTSC or the like by rotating the drum at 1800rpm in the case of MUSE and rotating it at 2700rpm in the case of NTSC(VHS) after winding a tape over 270 deg..

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 method and a magnetic recording / reproducing apparatus, and more particularly to a MUSE signal and NTSC.
The present invention relates to a magnetic recording / reproducing device capable of recording / reproducing by switching signals such as.

[0002]

2. Description of the Related Art Various HDTV VTRs for recording and reproducing MUSE signals used for HDTV developed by NHK or MTR VTRs have been proposed.

FIG. 8A is a waveform diagram of a band-compressed high-definition signal (hereinafter referred to as MUSE signal), in which a positive signal is used as a synchronizing signal. If the MUSE signal including the positive polarity sync signal is recorded on the VTR as it is, the sync signal cannot be separated during reproduction, and thus the sync signal cannot be used for jitter correction. Therefore, FIG.
As shown in (b), the MUSE signal is time-axis-compressed in units of 1H to provide a blanking period, in which a negative sync signal and a burst signal for jitter detection are inserted and added. That is, the VTR is used for recording in the same manner as the sync signal and burst signal in the NTSC signal. This method is based on Mitsubishi Electric Technical Report Vol. 60.N
o. 11 (published in 1986), "High-definition VTR broadband recording technology".

As another recording / reproducing system using the VTR of the MUSE signal, the latter half of the signal is delayed by a predetermined period so as to provide a blanking period at the signal position for rotary head switching at the time of recording, and then at the position for rotary head switching at the time of reproduction. There is one that corrects the skew. This method is shown in "Prototype of home-use high-definition VTR" in the 1987 National Conference of Television Society, and is as follows.

By delaying the latter half of the video signal of each field by 16H and providing a blanking period of 16H at the center of each field, the vertical blanking period is shortened by 16H, but a blanking period of about 20H still remains. In the two blanking periods provided in each field, a positive horizontal sync signal (referred to as pseudo H) that is phase-synchronized with the horizontal sync signal of the video is inserted to maintain continuity of synchronization. The rotation of the heads is controlled so that the switching between the two rotary heads is performed during this blanking period, and recording / reproduction is performed. During reproduction, the pseudo H period is deleted and the continuity of horizontal synchronization is maintained to remove rotary head switching noise and skew.
The horizontal sync signal recorded in the VTR is only the positive sync signal. In the pseudo H period, the horizontal sync signal is reliably detected,
In the video signal period following the pseudo H period, horizontal sync is detected by utilizing the shape and periodicity of the positive horizontal sync signal.

[0006]

Among the above two prior arts, the method of adding a negative sync signal similar to NTSC is
Assuming that the system and the system in which the blanking period is provided at the switching position of the rotary head is the B system, each of the A and B systems has the following problems. That is, it is difficult to correct the jitter (velocity error) within one horizontal period in both A and B systems. Further, in the A system, since the MUSE signal is compressed on the time axis, the band of the recorded video signal is widened to the higher side. Furthermore, in the A method, S / N due to FM deviation
Will deteriorate. Next, in the method B, since the skew correction is the main purpose, if there is a lot of jitter at a position other than the rotary head switching position, it may be difficult to detect the synchronization signal, and therefore it may be difficult to correct the jitter. is there. or,
It is not possible to directly record a signal such as a voice that has entered the vertical blanking period. Therefore, a separate voice head is required.

Therefore, the present invention overcomes the drawbacks of both the conventional A and B methods and achieves 1H in recording / reproducing MUSE signals.
It is possible to correct the time axis within the
It is an object of the present invention to provide a magnetic recording / reproducing method that can be shared with standard television signals such as C, PAL, and SECAM, and a magnetic recording device and a magnetic reproducing method used for the same.

[0008]

In order to achieve the above-mentioned object, according to the present invention, when recording a MUSE signal, an input MUSE is used.
The pilot signal of the specified frequency is superimposed outside the video signal band of the signal, and the synchronization signal of the specified frequency is superimposed on the frequency band that is lower than the frequency-modulated signal of the resulting multiplexed signal, and the resulting frequency is obtained. A multiplex signal is applied to a magnetic head to separate the sync signal from a signal reproduced from a magnetic recording medium to obtain a reproduction sync signal, and the reproduced signal is demodulated to obtain a reproduction multiplex signal. To obtain the reproduced pilot signal by separating the pilot signal from
A time axis correction is performed by writing from the reproduction multiplexed signal and the pilot signal to a buffer memory in synchronization with a clock signal of a predetermined frequency, and reading the demodulated video signal from the buffer memory with another stable clock signal. did.

Therefore, as means for use in the recording system of this method, means for expanding the input MUSE signal in the time axis, means for converting the signals obtained by the time axis expansion into signals of a plurality of channels, and the plurality of channels. Means for superimposing a pilot signal of a predetermined frequency on the outside of each video signal band of the signal, means for frequency-modulating the resulting multiplex signals of a plurality of channels, and more than the frequency-multiplexed multiplex signals. NTSC, PAL or S, means for superimposing a synchronization signal of a predetermined frequency on a low frequency band, means for applying the frequency multiplexed signals of a plurality of channels obtained by the superposition to a plurality of magnetic heads for recording on a magnetic recording medium.
Means for frequency-modulating one luminance signal of an input standard signal including an ECAM signal, means for frequency-converting a color signal of the standard signal into a frequency band lower than that of the frequency-converted luminance signal, and the frequency-converted color Provided is a magnetic recording device having means for superimposing a signal on the frequency-modulated luminance signal, and means for giving a color under system signal obtained by the superposition to the plurality of magnetic heads to record the signals on a magnetic recording medium. To be done.

Further, as means for use in the reproducing system of this method, means for separating a synchronizing signal superimposed at the time of recording from a reproducing signal containing MUSE signals of a plurality of channels reproduced from a magnetic recording medium by a plurality of magnetic heads, Means for demodulating the reproduction signal to obtain a reproduction multiplex signal, means for separating the pilot signal superimposed at the time of recording from the reproduction multiplex signal, and generating a clock signal of a predetermined frequency from the synchronization signal and the pilot signal Means, a buffer memory means for writing the demodulated video signal in the reproduction multiplexed signal in synchronization with the clock signal, a means for generating a clock signal for reading the recorded contents of the buffer memory means, and the plurality of magnetic fields. One of the standard signals including NTSC, PAL or SECAM signals reproduced from the magnetic recording medium by the head. Separating the color signal, means for converting the separated chrominance signal to a higher frequency, the magnetic reproducing apparatus is provided with a means for superimposing one of the luminance signal of the standard signal.

[0011]

In the magnetic recording / reproducing method, the magnetic recording apparatus and the magnetic reproducing apparatus of the present invention, the pilot signal and the synchronizing signal, which are superposed at the time of recording as described above, are separated from the reproduced signal at the time of reproducing, and a predetermined frequency is used by using these two signals. The clock signal is generated, the demodulated signal is written to the memory in synchronization with this clock signal, and then the other stable clock signal is read, so that the time axis correction can be performed accurately even within the range of 1H. It can be carried out.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are block diagrams showing an embodiment of a magnetic recording apparatus and a magnetic reproducing apparatus for carrying out the magnetic recording / reproducing method of the present invention. It goes without saying that the magnetic recording device and the magnetic reproducing device shown in FIGS. 1 and 2 can be integrated to form a magnetic recording / reproducing device, but here, the recording system and the reproducing system will be described separately. Hereinafter, they are simply referred to as a recording system and a reproducing system.

The input terminal NTSC IN has NTSC, P
It is assumed that one of standard signals such as AL and SECAM is input, and the MUSE signal used for high-definition is input to the other input terminal MUSE IN. Here, it is assumed that the NTSC signal is input as the standard signal. Two switches SW1, SW2 connected to these input terminals
And the other two switches SW3 and SW4 set the recording system to NT.
It is for switching between the SC mode and the MUSE mode, and it is preferable to use the interlocking one. These switches SW1, SW2, SW3, SW4 are NTSC
On the side, the NTSC signal is given to the VHS / MUSE recording processing circuit 24 and the COLOR / SYNC circuit 42. The VHS / MUSE recording processing circuit 24 frequency-modulates the Y (luminance) signal in the NTSC signal to obtain an FM signal, while the COLOR / SYNC circuit 42 has the switch SW3 of N.
On the TSC side, the C (color) signal in the NTSC signal is VHS
It is converted to the low frequency band according to a predetermined color under system such as (registered trademark). These signals are frequency-multiplexed with each other by an adder 24 to be signals of a predetermined color under system, and are passed through a recording amplifier 46 and a head switching circuit 48, as shown in FIG.
The four magnetic heads 56, 58, 60, 62 mounted on the rotating drum shown in FIG. 50 is a drum servo circuit, input NTSC
A drum motor (not shown) that drives the rotary drum is controlled in response to the signal synchronization signal. This drum servo circuit 5
The head switching pulse is generated by the head switching pulse generation circuit 52 using the signal of 0 and is given to the head switching circuit 48. Since the circuit components described above are basically the same as the recording system of a conventional VTR of, for example, the VHS system, no further description will be given.

On the other hand, the MUSE signal applied to the input terminal MUSE IN is divided into signals of 2 channels for each field, that is, 4 channels in total through the A / D converter 10, the MUSE signal processing circuit 12, and the D / A converter 14 group. To be done. The MUSE signal processing circuit 12 performs predetermined digital signal processing. Pilot signal generation circuit 32
Is a circuit for generating a continuous signal of a predetermined frequency in synchronization with the synchronizing signal of the input MUSE signal. This pilot signal is used for jitter correction in the reproduction system described later with reference to FIG. Assuming that the frequency band of the input MUSE signal is 8.1 MHz, the band of the recording signal per channel is the channel division number 2 and the drum rotation speed ratio of 2: 3 to 8.1 MHz × 1/2 × 2 / 3 = 2.7
It becomes MHz. Horizontal sync frequency of MUSE signal fH = 3
480fH × 1/3 × 3/5 = based on 480fH which is 480 times (the number of samples of the MUSE signal) 480 times 3.75 kHz
If it is 96 fH, the pilot signal will be 3.24 MHz. The diameter of the rotary drum is 4 as shown in FIG.
It is 1 mm and the magnetic tape is wound over 270 °. The rotation speed of the rotating drum is set to 1800 rpm in the MUSE mode and 2,700 rpm in the NTSC mode by switching the switch SW4.

FIG. 4 is a spectrum diagram showing the frequency relationship between the channel-divided MUSE signal and the pilot signal having a frequency of 96 fH. The pilot signal is adder 1
MUSE recording processing circuits 24, 26, which are respectively superposed on the MUSE signals divided by 6, 18, 20, and 22,
Given to 28 and 30. Of these, circuit 24 is NTS
It is also used as a C-based VHS. The MUSE recording processing circuits 24, 26, 28, 30 have an emphasis circuit, a frequency modulation circuit, etc., and have basically the same configuration as that for VHS. In this embodiment, the same pilot signal is added and superposed on each channel. However, it is more preferable that four different pilot signals are generated by performing fine phase control in consideration of H arrangement and magnetic tape speed. Is.

MUSE recording processing circuits 24, 26, 28,
The output FM signal of 30 has adders 34, 36, 38, 40
At, the synchronization signal output from the COLOR / SYNC circuit 42 is superimposed. That is, switch SW3 is MUSE
When set to the side, the COLOR / SYNC circuit 42 receives the input MU.
For example, a ternary sync signal as shown in FIG. 6 synchronized with the horizontal sync signal of the SE signal is generated. The frequency of this synchronizing signal is 40 fH × 1/4 = 10 fH = 337.5 kHz, which is lower than the frequency-modulated MUSE signal band as shown in FIG. The synchronization signal is superimposed on this band because the MUSE signal is the TCI signal and the VH
Since it is not necessary to add the low-frequency converted C signal to the frequency-modulated Y signal like the S signal, the additional band of the C signal in VHS can be used as the additional band of the synchronization signal.

4-channel FM with sync signal added
The signals are sequentially applied to the four magnetic heads 56, 58, 60 and 62 via the recording amplifier group 46 and the head switching circuit 48.

Next, the reproducing system shown in FIG. 2 will be described.
The magnetic heads 56, 58, 60 and 62 are shown as the same heads by using the same numbers as those of the recording system, but it goes without saying that they can be read-only machines. Switch SW5,
SW6, SW7, and SW8 are for switching between the MUSE mode and the NTSC mode as in the reproducing system. Drum servo circuit 50
A, switch SW5, head switching pulse generation circuit 52
A, head switching circuit 48A is for sequentially selecting one of the heads as in the recording system, and is also for NTSC and MUS.
With E, the speed of the rotary drum is switched as in the recording system. The clock signal generation circuit 64 is the drum servo circuit 50.
The reference clock is sent to A. The preamplifier group 66 amplifies the reproduction signal from the selected head and has four preamplifiers. Preamplifier group 6
The output signal of 6 is given to the P / S (parallel-serial) conversion circuit 68, and in the case of reproduction of an NTSC signal, a parallel sequential signal of 4 channels is converted into a serial signal. A clock signal for P / S conversion is sent from the drum servo circuit 50A. The serial signal is applied to the VHS / MUSE reproduction processing circuit 72, FM demodulated therein, and then applied to the NTSC processing circuit 80 via the switch SW8. The COLOR / SYNC circuit 70 converts the C signal of the VHS signal into a high frequency band in the NTSC mode, and separates the sync signal superimposed during recording in the MUSE mode. This mode switching is performed by the switch SW6. Therefore, in the NTSC mode, the high frequency converted C signal is applied to the NTSC processing circuit 80 via the switch SW7 and is superimposed on the FM demodulated Y signal to produce a composite video signal at the NTSC signal output terminal NTSC.
It is output from OUT. It should be noted that the Y / C separated state can be output as necessary.

The MUSE reproduction processing circuits 74, 76 and 78 are the same as those other than the VHS system portion of the VHS / MUSE reproduction processing circuit 72, and are for FM demodulating the MUSE signal. Each of these reproduction processing circuits 72, 74, 7
The output signals of 6 and 78 are supplied to the A / D converter group 84 and also to the clock signal generation circuit 82. The clock signal generation circuit 82 has a BPF for separating the pilot signal superimposed at the time of recording, and creates a write clock signal using the synchronization signal separated by the COLOR / SYNC circuit 70 described above as a reference signal. Is. This write clock signal is the pilot signal of 3.24 MHz (96 fH) as shown in FIG.
It is 5/3 times, that is, 5.4 MHz (160 fH). This write clock signal is used by the A / D converter group 8
As a sampling clock of 4 and T for time base correction
It is used for writing an A / D converted signal to the buffer memory 86 used as a BC (time base collector). COLOR / S as a writing standard
The 1H cycle write reference pulse obtained by the YNC circuit 70 is used.

In the TBC 86, digital signals sequentially written in 4 channels (2 fields × 2 channels) are read using a stable 480 fH clock for reading generated by the clock signal generation circuit 88, thereby converting serial data. Conversion and time axis correction, that is, jitter removal is performed. The output signal of TBC86 is MUSE
After a predetermined digital signal processing is performed by the signal processing circuit 90, it is converted into an analog MUSE signal by the D / A converter 92, and is output from the output terminal MUSE OUT as a MUSE output signal via an LPF (not shown).

In the above embodiment, the pilot signal is 96f.
I set it to H, but at frequencies other than this,
160 as a write clock signal to be given to the TBC 86
Any frequency that can generate a frequency of fH and can be frequency-modulated within the VHS signal band may be used. Further, the frequency was set to 10 fH as the synchronizing signal superimposed at the time of recording, but another frequency may be used as long as it is within the VHS color signal band and is an integral multiple of fH. Further, although this synchronizing signal uses a ternary signal in consideration of accuracy in the embodiment, it may be the same as the horizontal synchronizing signal in the NTSC system.

[0022]

As is apparent from the above description in detail, in the present invention, the continuous wave pilot signal and the synchronization signal added at the time of recording are separated at the time of reproduction, and the write clock signal to the TBC is generated by these signals. Since it is made, the velocity error can be corrected at the time of writing, and the residual jitter is reduced. Further, since the sync signal of the MUSE signal is detected at the time of reproduction by using the sync signal added at the time of recording, the detection can be stably performed, and the MUSE signal is time-axis compressed as in the conventional example. Since the sync signal is not added, the band of the MUSE signal does not expand. Further, when compared with the conventional example in which a 30% negative polarity sync signal is added, the S / N ratio is improved by about 3 dB when frequency modulation is performed with the same deviation.

Further, in the present invention, since the sync signal is added to the MUSE signal in the band of the color signal of the VHS signal, the band of the sync signal is lower than that of the FM signal, and therefore the sync signal of the magnetic recording / reproducing is generated. The dropout is small and the sync signal can be stably reproduced. Further, in addition to the above features, both MUSE signals and standard system signals such as NTSC can be recorded / reproduced by simply switching the mode, so that it is highly useful as a home VTR.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing an embodiment of a reproducing system of the present invention.

FIG. 3 is a plan view showing a relationship among a rotary drum, a magnetic head, and a magnetic tape used in an embodiment of the present invention.

FIG. 4 is a spectrum diagram showing a frequency relationship between a pilot signal and a MUSE signal in the present invention.

FIG. 5: Sync signal and frequency modulation MUSE in the present invention
It is a spectrum figure which shows the frequency relationship of a signal.

FIG. 6 is a timing chart of the recording system according to the present invention.

FIG. 7 is a timing chart of the reproducing system in the present invention.

[Explanation of symbols]

10 AD Converter 12 MUSE Signal Processing Circuit 13 Switch Circuit 14 D / A Converter Group 16, 18, 20, 22, 34, 36, 38, 40 Adder 24 VHS / MUSE Recording Processing Circuit 26, 28, 30 MUSE Recording Processing Circuit 32 pilot signal generation circuit 42,70 COLOR / SYNC circuit 46 recording amplifier group 48,48A head switching circuit 52,52A head switching pulse generation circuit 50,50A drum servo circuit 56,58,60,62 magnetic head 64,82,88 Clock signal circuit 66 Preamplifier group 68 P / S conversion circuit 72 VHS / MUSE reproduction processing circuit 74, 76, 78 MUSE reproduction processing circuit 80 NTSC processing circuit 84 A / D converter group 86 TBC (buffer memory) 90 MUSE signal processing circuit 92 D / Converter

[Procedure amendment]

[Submission date] September 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 8

[Correction method] Added

[Correction content]

FIG. 8 is a waveform diagram showing time axis compression of a MUSE signal.

Claims (3)

[Claims] 1. A pilot signal having a predetermined frequency is superimposed outside a video signal band of an input MUSE signal, the resulting multiplexed signal is frequency-modulated, and the predetermined frequency is synchronized with a frequency band lower than the frequency-modulated signal. The signals are superposed, the frequency-multiplexed signal obtained as a result is given to a magnetic head to record on a magnetic recording medium, and the sync signal is reproduced from the signal reproduced from the magnetic recording medium by the magnetic head or a separate magnetic head. To obtain a reproduction sync signal, demodulate the reproduced signal to obtain a reproduction multiplexed signal, separate the pilot signal from the reproduction multiplexed signal to obtain a reproduction pilot signal, and reproduce the reproduction synchronization signal and the pilot. A clock signal having a predetermined frequency is generated from the signal and the demodulated video signal in the reproduction multiplexed signal is written in the buffer memory in synchronization with the clock signal. A magnetic recording / reproducing method for performing time-axis correction by reading the demodulated video signal from the buffer memory with another fixed clock signal. 2. A means for expanding the input MUSE signal in the time axis, a means for converting the signal obtained by the time axis expansion into a signal of a plurality of channels, and a video signal band outside each of the signals of the plurality of channels. Means for superimposing a pilot signal of a predetermined frequency on the result, means for frequency-modulating the resulting multiplex signals of a plurality of channels, and a synchronization signal of a predetermined frequency in a frequency band lower than the plurality of frequency-modulated multiplex signals. NTSC, P, a means for superimposing a plurality of channels, a means for applying the frequency-multiplexed signals of a plurality of channels obtained by the superposition to a plurality of magnetic heads and recording them on a magnetic recording medium,
Means for frequency-modulating one luminance signal of an input standard signal including an AL or SECAM signal, means for frequency-converting a color signal of the standard signal into a frequency band lower than the frequency-modulated luminance signal, and the frequency-converted Magnetic recording apparatus having means for superimposing a color signal on the frequency-modulated luminance signal, and means for applying a color under system signal obtained by the superposition to the plurality of magnetic heads to record it on a magnetic recording medium. .. 3. A means for separating a synchronization signal superimposed at the time of recording from a reproduction signal containing MUSE signals of a plurality of channels reproduced from a magnetic recording medium by a plurality of magnetic heads,
Means for demodulating the reproduction signal to obtain a reproduction multiplex signal, means for separating the pilot signal superimposed at the time of recording from the reproduction multiplex signal, and generating a clock signal of a predetermined frequency from the synchronization signal and the pilot signal Means, buffer memory means for writing the demodulated video signal in the reproduction multiplexed signal in synchronization with the clock signal, means for generating a clock signal for reading the recorded contents of the buffer memory means, and the plurality of magnetic fields. NTSC, PAL or SEC reproduced from the magnetic recording medium by the head
Means for separating a color signal from one of the standard signals including an AM signal, means for converting the separated color signal into a high frequency, means for demodulating one luminance signal of the standard signal, and the demodulated luminance signal And a means for superimposing the color signal converted to the high frequency on the magnetic reproducing apparatus.