JPH0547881B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a magnetic recording method, and particularly to a magnetic recording method suitable for performing high-density magnetic recording.

(Description of Prior Art) In general, in order to increase the recording density in a magnetic recording device, it is necessary to reduce the track pitch. However, as the track pitch becomes smaller, leakage signals from adjacent tracks, so-called crosstalk components, will increase in the reproduced signal unless the trace position of the head is accurately aligned on the track during reproduction. Therefore, no matter how small the track pitch was, there was a limit depending on the mechanical accuracy.

Furthermore, in recent years, many methods have been proposed for recording a video signal and an accompanying audio signal on the same recording medium. For example, methods have been proposed in which a video signal and an audio signal are frequency multiplexed, or an audio signal is time-base compressed and inserted into the horizontal blanking period of the video signal. However, these methods generally require very complicated signal processing, which is not desirable. There is also a method of providing a track exclusively for audio signals on the same recording medium, but this has been a hindrance to high-density recording.

(Object of the Invention) In view of the above-mentioned problems, the present invention aims to provide a magnetic recording method that can realize high-density recording by effectively utilizing so-called azimuth loss without performing complicated signal processing. purpose.

(Explanation of Examples) Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a diagram showing the head arrangement of a magnetic recording/reproducing apparatus as an embodiment using the method of the present invention. In FIG. 1, 1 is a multi-head for video signal recording, and each head 1a, 1b, 1c, 1
A video signal is recorded by d. There are spacers 1a', 1b', and 1c' between each head, and when a video signal is recorded by the multihead 1, the portion traced by these spacers 1a', 1b', and 1c' is a guard band. becomes. 2 is a multi-head for recording audio signals, and each head 2a,
2b records, for example, a stereo audio signal. Heads 1a to 1d and heads 2a and 2b have different magnetization directions as shown by 3 in the figure, and are arranged so that a track is formed by heads 2a and 2b between tracks formed by heads 1a, 1b, 1c and 1d. has been done. 4 is an arrow indicating the running direction of the recording medium.

FIG. 2 is a diagram showing the recording system of the apparatus whose head configuration is shown in FIG. 1. In FIG. 2, 5 is a video signal input terminal, 6 is an analog-digital converter (A/D converter), 7 is a recording processor, 8a,
8b, 8c, 8d are amplifiers, 9a, 9b, 9
Terminals c and 9d supply signals to the heads 1a, 1b, 1c and 1d, 10a and 10b are terminals into which signals of one channel of the stereo audio signal are respectively input, 11a and 11b are FM modulators, 12a and 11b are FM modulators, respectively. 12b is an amplifier, 13a, 13
Terminals b supply signals to the heads 2a and 2b, respectively.

In this configuration, the analog video signal applied to the terminal 5 is A/D converted by the A/D converter 6 at a sampling frequency of 14.3 MHz (four times the frequency of the color subcarrier of the NTSC signal),
This is an 8-bit NRZ (non-return-to-zero) signal. Furthermore, it is distributed (rate down) into 4 tracks of digital signals in the recording processor 7,
After adding synchronization data necessary for digital recording, parity words for error correction, etc. to each signal, the signals are digitally modulated and supplied to recording amplifiers 8a, 8b, 8c, and 8d. The outputs of amplifiers 8a, 8b, 8c, and 8d are recorded on recording media by heads 1a, 1b, 1c, and 1d, respectively. Furthermore, recording amplifiers 8a, 8b, 8
In this example, the transmission bit rate at the outputs of bits c and 8d is 28.6 Mbit/S.

On the other hand, two-channel (L, R) stereo audio signals are supplied to terminals 10a and 10b, respectively, and are processed by FM modulators 11a and 11b, for example, with carrier frequencies of 8MHz and 10MHz, and a frequency deviation width of ±200K.
Hz FM modulation signal, recording amplifiers 12a, 1
2b, the head 2a, via the terminals 13a, 13b.
2b is recorded on the recording medium.

FIG. 3 is a diagram showing the spectral distribution of the recording signal by the apparatus shown in FIG. 2. In FIG. 3, reference numeral 14 represents the envelope curve of the spectrum level with respect to the frequency normalized by the information transmission frequency (28.6 MHz in this embodiment) when interleaved NRZI is used as the digital modulation method of the video signal. As shown in the figure, the frequency spectrum when a wideband video signal is digitally modulated generally has a wide range of spread.

On the other hand, 15 and 16 represent frequency spectra when 8 MHz and 10 MHz carriers are respectively FM modulated with each channel signal of the stereo audio signal. In the case of an audio signal, since it is generally a narrow band, it can be considered that the spectrum spread is only by the frequency deviation width (±200 KHz in this example).

When reproducing a signal recorded in this manner, if the trajectory traced by the reproducing head deviates from the recording track to be traced, crosstalk occurs between adjacent tracks. In the above example, since the magnetization directions are different in adjacent tracks, the amount of crosstalk is reduced due to azimuth loss.

The azimuth loss La is calculated by setting the head width to W, the azimuth angle to θ, and the recording wavelength to λ.La=20logsin(πW/λtanθ)/(πW/λ)tan
θ. Therefore, if the relative speed between the head and the recording medium is constant, La increases as the frequency increases. For example, if the track width W is 60 μm and the azimuth angle θ is 14 degrees, the crosstalk from the track where the audio signal is recorded to the track where the video signal is recorded will be 0.8 μm when the recording wavelength of the 8 MHz carrier is Then, La = -35 dB, which poses no practical problem. Of course, the crosstalk of the 10MHz carrier component will be reduced because the azimuth loss will further increase.

On the other hand, regarding crosstalk from a track where a video signal is recorded to a track where an audio signal is recorded,
For signal components above the carrier frequency, there is no problem as in the case described above, but for signal components in a low frequency band, reduction of crosstalk due to azimuth loss cannot be expected. But as mentioned above
Since the FM modulated audio signal has a narrow band, crosstalk components in the low frequency band can be easily removed using a filter or the like.

FIG. 4 is a block diagram showing the reproduction system of the apparatus shown in FIG. 2. Each head 1a to 1d, 2a, 2b
Tracks recorded with the same head shall be played back with the same head. 17a, 17b, 17c, 17d are terminals to which reproduction signals from the heads 1a, 1b, 1c, 1d are supplied, respectively; 18a, 18b, 18c, 18
d is a playback amplifier, 19 is a playback processor, 2
0 is digital-to-analog conversion (D/A conversion)
21 is an output terminal for the reproduced video signal, 22a,
22b are terminals to which reproduction signals from the heads 2a and 2b are supplied, respectively; 23a and 23b are amplifiers, respectively;
24a and 24b have center frequencies of 8MHz and 10M, respectively.
Hz bandpass filter (BPF), 25a, 25
b are FM demodulators, and 13a and 13b are terminals to which reproduced audio signals of the L channel and R channel are output, respectively.

The digital signals reproduced by the heads 1a, 1b, 1c, 1d are sent to reproduction amplifiers 18a, 18b,
18c and 18d, demodulation and error correction are performed for each signal in the reproduction processor 19, and the signal is multiplexed to become an NRZ signal.
The A converter 20 performs D/A conversion to generate the original analog video signal, which is output from the terminal 21. On the other hand, the FM modulated audio signals of each channel reproduced by the heads 2a and 2b are sent to the reproduction amplifier 23.
a, 23b, and after unnecessary band components are removed in BPF 24a, 24b as described above,
The original audio signals are converted to the original audio signals by the FM demodulators 25a and 25b, and reproduced stereo audio signals are obtained from the terminals 26a and 26b.

According to the above-mentioned configuration, for each track in the track group (first track group) on which video signals are recorded, there is a track group (second track group) on which audio signals are recorded arranged between the tracks. Since the magnetization direction of each track in the track group is different and the energy spectrum of the modulation signal of the audio signal is concentrated in the high range, when these are played back, the audio signal is recorded from the track where the video signal is recorded. Crosstalk from the track where the audio signal is recorded to the track where the video signal is recorded is attenuated by azimuth loss. Therefore, the track pitch can be made smaller than the so-called mechanical tracking accuracy, which is very effective for high-density recording.

It should be noted that the above-described embodiments do not limit the scope of the present invention, and the type of signal, the signal form of the recording signal, the head configuration, etc. can be changed as appropriate. For example, when applying the present invention to a VTR, two video signal rotary heads with the same azimuth angle are used to sequentially form diagonal tracks while recording the video signal using a well-known low frequency conversion recording method. The present invention can be easily carried out by a method such as forming an audio-dedicated track with an audio rotary head whose azimuth angle is different from the above-described video signal rotary head and recording in the same recording signal form as in the above-described embodiment. Applicable.

(Description of Effects) As explained above using the embodiments, according to the magnetic recording method of the present invention, by skillfully utilizing the azimuth loss and its characteristics, the track pitch can be made smaller than mechanical accuracy. High-density recording can be achieved without complex signal processing.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the head arrangement of a magnetic recording/reproducing apparatus as an embodiment using the method of the present invention, FIG. 2 is a diagram showing the recording system of the apparatus whose head configuration is shown in FIG. 1, and FIG. is a diagram showing the spectrum distribution of the recorded signal by the recording system shown in Figure 2, and Figure 4 is a diagram showing the spectrum distribution of the recording signal by the recording system shown in Figure 2.
FIG. 2 is a diagram showing a reproduction system corresponding to the recording system shown in the figure. 1a, 1b, 1c, and 1d are heads forming each track of the first track group, 2a and 2b are heads forming each track of the second track group, 7 is a recording processor, and 11a and 11b are each heads. FM modulator, 14 is head 1a, 1b, 1
15 is the spectrum distribution of the signal recorded by the head 2a, and 16 is the spectrum distribution of the signal recorded by the head 2b.

Claims (1)

[Scope of Claims] 1 A digitally modulated signal is recorded in a first track group, a frequency modulated signal is recorded in a second track group, and each track in the first track group is After formation,
A magnetic recording method characterized in that each track of the second track group is formed between them, and each adjacent track of the first and second track groups has a different magnetization direction.