JPH11205746A - Multiplex magnetic recording method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record an analog information signal and a digital information signal in a magnetic recording medium by multiplexing and to execute multiplex recording which can be given speedy reproduction of an optional speed rate. SOLUTION: Concerning a luminance signal separated and taken out at an analog signal processing circuit 3, at the time of a second mode, high frequency components equal to or higher than a prescribed cut off frequency are removed by a low-frequency filter 5, then supplied for an FM modulator 7 through a change-over switch 4 switch-connected to a terminal 4b, given frequency division multiplex with a low frequency conversion and carrying chrominance signal from the circuit 3 by mixing circuit 8 and then recorded in a magnetic tape 13 by a rotary head A. A digital signal from a digital signal processing circuit 10 is over-write-recorded in an analog video signal recording track by a rotary head D.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex magnetic recording method and a multiplex magnetic recording apparatus, and more particularly to a multiplex magnetic recording method and a multiplex magnetic recording apparatus for multiplexing an analog information signal and a digital information signal and recording the multiplexed information on a magnetic recording medium. About.

[0002]

2. Description of the Related Art In recent years, MPEG (Moving Picture Exper
ts Group), satellite broadcasting using digital signals compressed and coded based on the standards (hereinafter referred to as MPEG transport stream) has begun, and the development of a helical scan VTR that records the MPEG transport stream as it is for recording is announced. Have been.

On the other hand, among helical scan type VTRs, there is known a VTR for recording an analog information signal and a digital signal on the same magnetic tape (Japanese Patent Laid-Open Publication No. Hei 6-1994).
233318, JP-A-6-14343).
The invention described in Japanese Patent Application Laid-Open No. Hei 6-233318 discloses the first 2
Analog video signal recording tracks are alternately formed on magnetic tape with guard bands sandwiched by rotating heads for recording,
Digital video signal recording tracks are sequentially formed on the magnetic tape in the guard band by the second two recording rotary heads.

The invention described in Japanese Patent Application Laid-Open No. Hei 6-14343 discloses a method in which an analog video signal is recorded by forming sequential tracks on a magnetic tape using a first two recording rotary heads, Digital video signals are sequentially recorded on the recording tracks by two recording rotary heads. here,
Analog video signals are recorded over the entire magnetic layer of the magnetic tape, but digital video signals recorded later are recorded only on the upper layer of the magnetic layer on the same track.
Since the previously recorded analog video signal recording portion remains in the lower layer portion of the magnetic layer, an analog video signal and a digital video signal can be recorded at the same track position.

[0005]

SUMMARY OF THE INVENTION However, the above MP
In a conventional magnetic recording device (helical scan type VTR) that records an EG transport stream as it is,
For trick play, the received MPEG transport stream cannot be used, and data for trick play is generated, and a special position for trick play different from the recording position of the received MPEG transport stream is used. Must be recorded independently, and the apparatus becomes expensive. For example, the M generated from the received MPEG transport stream
A predetermined number of data blocks of PEG data must be distributedly recorded at a part of each track at a track interval according to the speed ratio of the special reproduction along the head scanning trajectory during the special reproduction. In addition, this conventional apparatus cannot perform special reproduction at a speed ratio other than the speed ratio of the recorded special reproduction data.

Further, in the conventional apparatus described in Japanese Patent Application Laid-Open No. 6-233318, since the analog video signal and the digital video signal are recorded on different tracks, the tape use efficiency is low. On the other hand, in the conventional apparatus described in Japanese Patent Application Laid-Open No. 6-14343, since the analog video signal and the digital video signal are multiplex-recorded on the same track, the tape use efficiency is good, but in reality, the reproduced image quality is significantly deteriorated. And cannot withstand practical use. In other words, the analog video signal overwritten by the digital video signal has a low-pass tendency in which the reproduction output decreases and the reproduction output decreases as the high-frequency signal increases in space loss. The reproduction system detects that the phase of the carrier wave at the high frequency of the video signal is inverted (hereinafter simply referred to as inversion), and the reproduced image quality is significantly deteriorated.

[0007] The present invention has been made in view of the above points,
An object of the present invention is to provide a multiplex magnetic recording method and a multiplex magnetic recording apparatus capable of multiplexing an analog information signal and a digital information signal and recording the multiplexed information on a magnetic recording medium, and performing multiplex recording capable of high-speed reproduction at an arbitrary speed ratio. I do.

It is another object of the present invention to provide a multiplex magnetic recording method and a multiplex magnetic recording apparatus capable of multiplex-recording an analog video signal having good reproduction image quality on a digital information signal.

[0009]

In order to achieve the above object, a multiplex magnetic recording method according to the present invention comprises first and second azimuth angles different from each other and attached to a rotating surface of a rotating body so as to face each other. Using a rotating head alternately, a magnetic recording medium running obliquely over a predetermined angle range around the outer peripheral side surface of the rotating body and running at a constant speed has a second analog video signal with a frequency component higher than a predetermined frequency removed. One track is sequentially formed and recorded, and the first and second rotary heads have different azimuth angles, and have different azimuth angles from each other.
And using the third and fourth rotary heads alternately mounted at different positions from the second rotary head to overwrite and record the second track by the digital information signal after forming the first track. It is something to do.

In order to achieve the above object, a multiplex magnetic recording apparatus according to the present invention comprises first and second azimuth angles different from each other, which are attached to a rotating surface of a rotating body so as to face each other.
A first track is sequentially formed by an analog video signal on a magnetic recording medium which is wound obliquely over a predetermined angle range around an outer peripheral side surface of a rotating body and runs at a constant speed by using the rotating heads alternately. Azimuth angles are different from those of the first and second rotary heads, and are different from each other. In a multiplex magnetic recording apparatus that uses a third and fourth rotary heads attached at positions alternately to overwrite and record a second track based on a digital information signal after the formation of the first track, an analog image is recorded. High frequency reduction means for reducing or removing a frequency component of a signal higher than a predetermined frequency as compared with normal recording, and high frequency reduction means for recording only an analog video signal. Switching means for selecting an input analog video signal and selecting an output analog video signal of the high frequency reduction means when recording the analog video signal and the digital information signal and supplying the selected analog video signal to the first and second rotary heads; It is configured.

According to the method and apparatus of the present invention, when multiplexing an analog video signal and a digital information signal, the high frequency of the analog video signal is reduced or eliminated and the analog video signal is sequentially recorded on the analog video signal track.
Recording that enables reproduction of an analog video signal can be performed without inverting the frequency modulation luminance signal.

In the method and apparatus according to the present invention, the analog video signal is a frequency division multiplexed signal of the low-frequency conversion carrier chrominance signal and the frequency-modulated luminance signal, and has the same video information as the video data in the digital information signal. The content of the digital information signal is such that an MPEG transport stream is converted into a predetermined format and recorded, so that an MPEG transport stream such as a satellite broadcast can be directly recorded on a digital information signal recording track and used for special reproduction. A video signal for special reproduction of digital information can be recorded on an analog video signal recording track without providing a circuit for generating a video signal.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a multiplex magnetic recording apparatus according to the present invention. Referring to FIG. 1, an NTSC color video signal as an example of an analog video signal input from an input terminal 1 is supplied to an analog signal processing circuit 3 and transmitted with a luminance signal in the same manner as in the existing VHS VTR signal processing. The chrominance signal is separated from the chrominance signal, and the chrominance subcarrier frequency is changed from 3.58 MHz to 62.
After being frequency-converted into a low-frequency conversion carrier color signal of 9 kHz,
It is supplied to the synthesis circuit 8.

The separated luminance signal is supplied to terminals 4a and 4b of the changeover switch 4. Here, the changeover switch 4 is connected to the terminal 4a in the first mode for recording only the analog video signal, and is connected to the terminal 4b in the second mode for multiplex-recording the analog video signal and the digital information signal. Connected to. Accordingly, in the first mode, the luminance signal separated and taken out by the analog signal processing circuit 3 is directly supplied to the FM modulator 7 through the changeover switch 4 connected to the terminal 4a, and the second mode is outputted. Sometimes low pass filter (LPF)
5, a predetermined cutoff frequency (for example, 1 to 2 MHz)
z) After the high frequency components above are removed, the high frequency components are supplied to the FM modulator 7 through the changeover switch 4 connected to the terminal 4b.

The FM modulator 7 frequency-modulates the input luminance signal in the baseband to generate a frequency-modulated luminance signal having a carrier shift frequency of 3.4 MHz to 4.4 MHz. The frequency-modulated luminance signal is supplied to the synthesizing circuit 8, where it is frequency-division multiplexed with the low-frequency conversion carrier chrominance signal from the analog signal processing circuit 3, and then amplified by the recording amplifier 9 to form a rotary transformer (not shown). The recording head is supplied to the rotary head A for recording an analog video signal through the recording medium, and the analog video signal recording track is sequentially formed on the magnetic tape 13 and recorded.

On the other hand, the MPEG input from the input terminal 2
The MPEG transport stream compressed and encoded according to the system is supplied to the digital signal processing circuit 10, where it is encoded in the same manner as the D-VHS encoder, and a predetermined number of data blocks (described later) are sequentially recorded on the track. In order to record a sync block, a digital signal (video signal,
(Including an audio signal and other information), and are further scrambled, and then synthesized with a sync pattern or an amble pattern in a time-series manner.

The digital signal which has undergone such signal processing and has a predetermined signal format is supplied to a modulator 11 and modulated by a modulation method suitable for magnetic recording and reproduction, and then amplified by a recording amplifier 12. Is supplied to a rotary head D for digital video signal recording via a rotary transformer (not shown), whereby the analog video signal recording track on the magnetic tape 13 is overwritten and recorded. Although the analog video signal input to the input terminal 1 and the information content of the MPEG transport stream input to the input terminal 2 may be different, in this embodiment, the analog video signal input to the input terminal 1 is different. The signal is sent to the MPE by a decoder (set top box) not shown.
This is an analog video signal obtained by decoding the G transport stream, and has the same information content as the MPEG transport stream input to the input terminal 2.

The analog video signal recording rotary head A is provided with two rotary heads A1 and A2 having different azimuth angles provided opposite to each other (adjacent to each other by 180 °) on the rotating surface of the rotary drum 15. The rotary head D for recording digital information signals includes two rotary heads D1 and D2 having different azimuth angles and provided on the rotating surface of the rotary drum 15 so as to face each other. The rotating head A1 is about 90 degrees with respect to the rotating head D2, and the rotating head A2 is about 90 degrees with respect to the rotating head D1.
It is provided ahead of the rotation direction by about °.

Further, the azimuth angles of the rotary heads A1 and A2 are standardized by the VHS (registered trademark) method.
6 ° and -6 °, and the track width is 3
6 μm. The azimuth angles of the rotary heads D1 and D2 are set to + 30 ° and −30 °, and the track widths are each set to 32 μm.

The rotary heads A1 and A2 are mounted on the rotary drum 15 at the same height, and the rotary heads D1 and D2 are mounted on the rotary drum 15 at the same height. The relative height positions of the rotary heads A1 and A2 and the rotary heads D1 and D2 are determined by forming analog video signal recording tracks by the rotary heads A1 and A2, and then setting digital signal recording tracks by the rotary heads D2 and D1. It is sufficient if the relative height position allows overwrite recording on the analog video signal recording track, and the track center lines of both tracks may not be coincident.

The rotating drum 15 is driven by a motor (not shown) counterclockwise in FIG.
A cylindrical rotating body that rotates at 97 rps. The outer circumferential side surface of the rotating drum 15 is provided below the rotating drum 15 (in a direction perpendicular to the paper surface) over an angle range slightly larger than 180 ° of the rotating drum 15. The magnetic tape 13 is wound obliquely by being guided by a tape guide formed on a fixed drum (not shown) which is arranged to face the space. The magnetic tape 13 runs at a constant speed in a predetermined direction during recording while maintaining the wound state.

Thus, in the first mode in which only the analog video signal is recorded, the analog video signal recording tracks are alternately formed on the magnetic tape 13 by the rotary heads A1 and A2 in the same manner as in the conventional helical scan VTR. Records are formed.

On the other hand, in the second mode in which the analog video signal and the digital information signal are multiplex-recorded, the first track is extended to the deep portion of the magnetic layer on the magnetic tape 13 by the rotary head A1 having an azimuth angle of + 6 °. Forming
After recording the frequency division multiplexed signal of the low frequency component of the luminance signal and the low-frequency conversion carrier chrominance signal, the surface of the magnetic layer of the magnetic tape 13 is formed on the first track by the rotating head D2 having an azimuth angle of -30 °. A second track is formed in the portion to record a digital information signal in a predetermined format.

Subsequently, a third track is formed by the rotary head A2 having an azimuth angle of -6 ° up to a deep portion of the magnetic layer on the magnetic tape 13, and a low-frequency component of a luminance signal and a low-frequency conversion carrier color signal are formed. After recording the frequency division multiplexed signal with the third head by the rotating head D1 having an azimuth angle of + 30 °.
The fourth track is formed on the surface layer of the magnetic layer of the magnetic tape 13 at the track portion of (3) to record a digital information signal of a predetermined format. Hereinafter, the same operation as described above is repeated, and tracks are formed at a track pitch of, for example, 29 μm. Therefore, the analog video signal recording portion on the surface layer of the magnetic layer of the magnetic tape 13 is erased by the digital information signal recording portion which is overwritten later, but the analog video signal recording portion on the deep portion of the magnetic layer remains as it is. Therefore, it can coexist with the digital information signal recording unit.

Each of the digital information signal recording tracks is provided with a fixed amount of data area called a sync block corresponding to a data block.
1, D2). FIG. 3 shows an example format of this sync block. As shown in the figure, the sync block has a 2-byte synchronization signal (Sy) for reproducing the sync block.
nc) area 21 and 3-byte address information (ID)
Area 22, a 3-byte header storage area 23 for storing various information, a 96-byte substantial data storage area 24, and an 8-byte parity area 25 for error correction of the sync block information. Are chronologically combined to form a total of 112 bytes.

FIG. 4 shows an example of a track format of each of the digital information signal recording tracks on the magnetic tape 13. As shown in the figure, one track includes a margin area 31, a preamble area 32, a subcode area 33, a postamble area 34, and an IBG area 3.
5, a preamble area 36, a main data area 37, an error correction code area 38, a postamble area 39, and a margin area 40, and are composed of 356 sync blocks in total.

When reproducing the analog video signal and the digital information signal multiplex-recorded on the magnetic tape 13 in this manner, two opposite analog video signals having the same configuration as the rotary heads A1 and A2 shown in FIG. Reproduction is performed using a reproduction rotary head and two opposed rotary heads for digital information signal reproduction having the same configuration as the rotary head D (D1, D2).

Here, since the azimuth angle of the digital information signal recording track is significantly different from the azimuth angle of the rotary head for reproducing the analog video signal recording track, the azimuth loss causes the digital information to be recorded by the rotary head for reproducing the analog video signal recording track. The signal is hardly reproduced, and can be reproduced only by the rotary head for reproducing the digital information signal recording track. Therefore, when reproducing the information content in which the MPEG transport stream is recorded as it is, it is possible to reproduce with high quality using only the rotary head for reproducing the digital information signal recording track.

Similarly, the azimuth angle of the analog video signal recording track is significantly different from the azimuth angle of the rotary head for reproducing the digital information signal recording track. The signal is hardly reproduced, and can be reproduced only by the rotating head for reproducing the analog video signal recording track. The analog video signal recording track is reproduced only during special reproduction such as high-speed reproduction.

Here, since the analog video signal is overwritten by the digital information signal, the reproduction output is lower than when the overwrite recording is not performed, and the high frequency component is reduced. However, in this embodiment, since the high-frequency component is removed and recorded by the low-pass filter 5, the inversion of the FM signal can be prevented.

Although the image quality of the analog video signal is slightly reduced by the reduction of the reproduction output and the removal of the high frequency components, the analog video signal is used for searching and confirming the recorded contents in a short time. Since it is used during high-speed reproduction, practically sufficient image quality can be obtained as a high-speed reproduction image. Moreover, in this embodiment, since the analog video signal recording track has the video content continuously recorded on the sequential analog video signal recording track, a high-speed reproduction image can be obtained at any high-speed reproduction at any speed ratio. it can.

As a VTR having a mode for multiplex recording an analog video signal and a digital information signal,
By simply adding only the low-pass filter 5 and the changeover switch 4 of FIG. 1, the other circuit parts and rotating heads can be used, so that a substantial special reproduction of the recorded digital signal can be performed with an extremely simple configuration. Further, the low-pass filter 5 is provided with an emphasis circuit for emphasizing the high frequency of the recording frequency of the luminance signal in the analog video signal recording system for recording only the analog video signal. (Not used).

[0033]

As described above, according to the present invention,
When multiplexing an analog video signal and a digital information signal, the high frequency band of the analog video signal is reduced or eliminated and the analog video signal is recorded on a sequential analog video signal track. In addition, a special reproduction video signal of the video content in the digital information signal can be obtained with a practically sufficient image quality.

Further, according to the present invention, since the high frequency of the analog video signal is reduced or eliminated and recorded on the sequential analog video signal track, it is not necessary to provide a dedicated special reproduction video signal generation circuit. With a simple configuration,
It is possible to record a video signal that can be specially reproduced at an arbitrary speed ratio.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a state in which a rotary head according to an embodiment of the present invention is mounted on a rotary drum.

FIG. 3 is a diagram showing an example of a format of a sync block of a digital information signal recorded by the apparatus of FIG. 1;

FIG. 4 is a diagram showing an example of a format of a digital information signal recording track recorded by the apparatus shown in FIG.

[Description of Signs] 1 Analog video signal input terminal 2 MPEG transport stream input terminal 3 Analog signal processing circuit 4 Changeover switch 5 Low-pass filter (LPF) 7 FM modulator 8 Synthesis circuit 9, 12 Recording amplifier 10 Digital signal processing circuit DESCRIPTION OF SYMBOLS 11 Modulator 12 Recording amplifier 13 Magnetic tape 15 Rotating drum A, A1, A2 Rotating head for recording analog video signal D, D1, D2 Rotating head for recording digital information signal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 9/804 H04N 9/79 J 9/808 9/80 B 9/83

Claims (6)

[Claims] 1. The method according to claim 1, wherein the first and second rotating heads having opposite azimuth angles are attached to a rotating surface of the rotating body so as to be inclined over a predetermined angle range on the outer peripheral side surface of the rotating body. First tracks are sequentially formed by an analog video signal from which a frequency component higher than a predetermined frequency has been removed and recorded on a magnetic recording medium wound around and running at a constant speed, and the first and second rotations are performed. A third and a third heads, which have different azimuth angles from the heads and have different azimuth angles from each other, are attached to positions different from the first and second rotary heads in opposition to the rotating surface of the rotating body. 4. A multiplex magnetic recording method, comprising: using a rotary head of No. 4 alternately to overwrite and record a second track by a digital information signal after the formation of the first track. 2. The digital video signal according to claim 1, wherein the analog video signal is a frequency-division multiplexed signal of a low-frequency conversion carrier color signal and a frequency-modulated luminance signal, and has the same video information content as video data in the digital information signal. 2. The multiplex magnetic recording apparatus according to claim 1, wherein a high frequency component higher than the predetermined frequency of the signal is removed and recorded, and the digital information signal is recorded by converting an MPEG transport stream into a predetermined format. Recording method. 3. An outer peripheral side surface of the rotating body is inclined over a predetermined angle range by alternately using first and second rotating heads having different azimuth angles mounted opposite to each other on a rotating surface of the rotating body. A first track based on an analog video signal is sequentially formed and recorded on a magnetic recording medium that is wound around and travels at a constant speed, and the azimuth angles are different from those of the first and second rotary heads, respectively. And alternately using third and fourth rotating heads, which have different azimuth angles and are attached to different positions from the first and second rotating heads, facing the rotating surface of the rotating body. A multiplex magnetic recording apparatus for recording a second track based on a digital information signal by overwriting after the formation of the first track and recording the same. High frequency reduction means for reducing or removing than at the time of normal recording, and when recording only the analog video signal, select the input analog video signal of the high frequency reduction means, the analog video signal and the A multiplex magnetic recording apparatus comprising: a switching unit that selects an analog video signal output from the high frequency frequency reduction unit and supplies the analog video signal to the first and second rotary heads when recording a digital information signal. 4. The analog video signal is a frequency-division multiplexed signal of a low-frequency conversion carrier color signal and a frequency-modulated luminance signal, and has the same video information content as video data in the digital information signal. The digital information signal is M
4. The multiplex magnetic recording apparatus according to claim 3, wherein the PEG transport stream is converted into a predetermined format and recorded. 5. The low-pass filter circuit according to claim 3, wherein the high-frequency reducing unit is a low-pass filter circuit that reduces or removes a frequency component of the analog video signal having a frequency equal to or higher than a predetermined frequency as compared with a normal recording. 5. The multiplex magnetic recording apparatus according to 4. 6. The high frequency frequency reducing means is means for disabling an emphasis circuit for high frequency frequency emphasis used when recording only the analog video signal when recording the digital information signal. 5. The multiplex magnetic recording apparatus according to claim 3, wherein: