JPS6394403A - Magnetic recording method - Google Patents

Abstract

PURPOSE:To decrease the deterioration of the recorded information of a main track due to a magnetic head for a guard band by setting the magnetomotive force of a magnetic head for a guard band to the scope of 40% to 80% of the magnetomotive force of the magnetic head for the main track. CONSTITUTION:A compound magnetic head 6 is equipped with magnetic heads 7 and 8 for a main track and a magnetic head 9 for a guard band in a single body. On a magnetic ferrite substrate 10, lower part magnetic layers 11 and 16 of the heads 7 and 8 are film-formed, and through insulating layers 12 and 17, a coil conductor and further, upper part magnetic layers 13 and 18 and a protecting layer 14 are successively formed. On the heads 7 and 8, the head 9 composed of a substrate 19, a lower part magnetic layer 20, an insulating layer 21, a coil conductor, an upper part magnetic layer 22 and a protecting layer 23 is bonded. The magnetomotive force of the head 9 is set to the scope of 40% to 80% of the magnetomotive force of the heads 7 and 8 and the deterioration of the recorded information to the main track due to the head 9 can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for recording information in an annular gap called a guard band formed between annular main tracks of a magnetic disk.

More specifically, the present invention provides an appropriate magnetomotive force relationship between the magnetic head for recording information on the main track and the magnetic head for recording information on the guard band. Even if the magnetic head off-tracks the recorded main track and overlays other information on a part of it, the information recorded on the main track does not deteriorate, and the guard band retains the specified information in a sufficiently good condition. This invention relates to a method for recording and reproducing data.

<Prior Art> When recording information on a magnetic disk, such as a floppy disk, the floppy disk is rotated and information is recorded on annular tracks.

Also, generally, a guard band is provided between two adjacent tracks. The guard band is provided to absorb tracking deviations due to expansion and contraction of the floppy disk due to changes in temperature and humidity and positioning errors due to accuracy of the head tracking mechanism.

There are various types of magnetic recording devices that use floppy disks as recording media, but still image recording devices such as so-called electronic still cameras convert the image of a subject obtained through a lens into an electrical signal and record it on a floppy disk. It has been known. A floppy disk for this purpose is called a video floppy. For reproduction, there is known a device that rotates a floppy disk and reproduces an image signal recorded on a track as a still image on a display device such as a television receiver. In these devices, one field of the image signal is recorded in one round of the track. This method of reproducing one still image using image signals for one field is called field recording and reproducing. In addition, a method of recording one field of the same frame on two tracks each, constructing one frame using the image signals from the two tracks, and playing back one still image is called frame recording and playback. . According to the standards for electronic still cameras, a floppy disk has a size of 3600.
rpm and a 60 μm wide track is 100 μm
They are formed concentrically with a pitch of . The width of the guard band is nominally 40 μm, and the allowable width of the track radius due to expansion and contraction of the floppy disk is ±14 μm.

On the other hand, when displaying still images on a television receiver, etc.
It is conceivable to output audio, music, etc. corresponding to the image signal at the same time, and a method of recording this information on a guard band is disclosed in JP-A-61-129701 and JP-A-61-15.
No. 3803, respectively. In other words, the conventional track is used as the main track to record image signals, and the guard band between the main tracks is used to temporally compress and record information signals such as audio. Record the signal as desired. The information signal recorded in a temporally compressed manner is expanded to its original state during playback. The magnetic head for recording image signals on the main track and the magnetic head for recording information signals on the guard band may be provided independently, or they may be integrated as proposed in JP-A-61-129701. Sometimes I get angry.

Information signals such as audio are generally recorded on a guard band adjacent to the main track after a corresponding image signal is recorded on the main track.

Regarding the recording current, assuming that the characteristics of the main track magnetic head and the guard band magnetic head are the same, the same value of recording current is caused to flow through both heads. This is because the image signal and the time-compressed information signal have substantially the same frequency band, so the optimal current value for each recording is the same. Note that when the characteristics of the magnetic heads, such as the number of coil windings, are different, the i&speed recording current values of the main track and guard band magnetic heads are generally different, but their respective magnetomotive forces are approximately the same.

The above is the same when recording image signals on the main track and the guard band, respectively, and also when arbitrary signals in substantially the same frequency band are recorded on the main track and the guard band, respectively.

<Problems to be Solved by the Invention> By the way, as mentioned above, tracking deviation is unavoidable. Therefore, when recording information on the guard band, as shown in FIG.
Information is recorded overlapping part 3 of the image.

At this time, if information has already been recorded on the main track 2, the information in the overlapped portion 3 of the information on the main track 2 will deteriorate. In FIG. 5, 4 is a guard band, and 5 is a recording area of information recorded by the guard band recording magnetic head.

In view of the above-mentioned problems, the present invention has been devised so that even if the guard band recording magnetic head off-tracks to the main track and records other information in a part thereof in an overlapping manner, the information already recorded on the main track is not deteriorated. First, it is an object of the present invention to provide a method that can record predetermined information on a guard band sufficiently well.

Means for Solving the Problems> In the magnetic recording method according to the present invention, desired information is first recorded on the main track of a magnetic disk by a magnetic head. Next, other information is recorded on a guard band adjacent to the recorded main track using a magnetic head having a predetermined azimuth angle. However, a so-called optimum recording current is applied to the main track magnetic head. Further, a recording current is passed through the guard band magnetic head so that its magnetomotive force is in the range of 40% to 80% of the magnetomotive force of the main track magnetic head.

Note that the information recorded on the main track is mainly an image signal, but basically any signal. In addition, the information recorded in the guard band is basically an arbitrary signal, but
When an image signal is recorded on the main track, it is mainly a time-compressed audio domain signal.

Effect: If information is recorded using the guard band magnetic head overlapping a part of the main track, the information already recorded on the main track will deteriorate. It has been found that the degree of this deterioration is reduced as the magnetomotive force of the guard band magnetic head is smaller than the magnetomotive force of the main track magnetic head. Conventionally, since the optimum recording current was passed through the guard band magnetic head, the magnetomotive force of this magnetic head was on the same level as that of the main track magnetic head, resulting in severe information deterioration on the main track. Experiments have shown that if the recording current of the guard band magnetic head is lowered than the optimum value and its magnetomotive force is 80% or less of that of the main track magnetic head, the deterioration of information on the main track can be kept to an acceptable level. understood.

On the other hand, if the magnetomotive force of the guard band magnetic head is made too small, information cannot be recorded satisfactorily on the guard band. However, experiments have shown that if the magnetomotive force of the guard band magnetic head is 40% or more of that of the main track magnetic head, information can be recorded satisfactorily even on the guard band.

Note that if the optimum recording current is applied to the main track magnetic head as in the past, information is recorded extremely well in the main track in advance, and the deterioration of information caused during guard band recording is reduced.

Embodiments The magnetic recording method according to the present invention will be explained in detail with reference to FIGS. 1 to 4.

FIG. 1 is a characteristic diagram showing how the C/N of main track information and the C/N of guard band information change when the recording current of the guard band magnetic head is changed. Figure 2 shows the C/N of the main track information and the C/N of the guard band information when the amount of overlap is changed.
FIG. 3 is a characteristic diagram showing how /N changes. FIG. 3 is a diagram illustrating a measurement method in an experiment to obtain the characteristics shown in FIGS. 1 and 2. FIG. 4 is a front view showing the sliding surface of the magnetic head used in the experiment.

A floppy disk for an electronic still camera was used in the experiment, and the 50th track (located at the innermost circumference of the recording area, where the relative speed between the magnetic head and the recording medium is the smallest), which had poor conditions, was used as the main track. Measurements were taken.

The floppy disk was rotated at a standard speed of 3600 rpm, and a 3-channel composite magnetic head 6 as shown in FIG. 4 was used.

This composite magnetic head 6 integrally includes two main track magnetic heads 7.8 and one guard band magnetic head 9. Specifically, each magnetic head 7
．． 8.9 is a thin film magnetic head in which a magnetic layer, a conductive layer, and an insulating layer are each formed of thin films.

In FIG. 4, a magnetic alloy is sputtered onto a magnetic ferrite substrate 10 to form lower magnetic rtjJ11, 16 of a thin film magnetic head 7.8. An insulating layer 12.17 is formed on the lower magnetic layer 11.16, and a coil conductor (not shown) is formed thereon. A magnetic alloy is sputtered onto these laminates to form an upper magnetic layer 75.
13 and 18 are formed, and a protective layer 14 is formed thereon. On top of these magnetic heads 7.8, a thin film magnetic head 9 consisting of a substrate 19, a lower magnetic layer 20, an insulating layer 21, a coil conductor (not shown), an upper magnetic layer 22, and a protective layer 23 is made of low melting point glass. It is attached with etc.

24 is a non-magnetic protective plate, which is made of low melting point glass etc. to maintain EI.
It is glued onto II23.

The two main track magnetic heads 7.8 each have a magnetic gap portion 7& that forms a track with an azimuth angle of zero and a width of 60 μm.

It has 8a. Also, the two magnetic heads 7.8 are 40 μm thick.
The magnetic gap part 7m is formed so as to form a guard band.
, 8m and 40 μmW in the track width direction. On the other hand, the guard band magnetic head 9 has a magnetic gap portion 9a having an azimuth angle of 45 degrees and forming a track with a width of 40 μm. This magnetic head 9 is arranged so that the track formed by it is exactly adjacent to the main track formed by the two magnetic heads 7.8. Also, each magnetic head? , 8.9 are made so that the magnetomotive force is the same if the recording current is the same, the gap length is 0.33 μm, and the image signal is recorded using frequency modulation (FM). The optimum recording current for each case is 50 mAp.

Furthermore, in the experiment, a 7 MHz single frequency signal was recorded on the main track, and a 6 MHz single frequency signal was recorded on the guard band.

The reason for this is that image signals are generally recorded on the main track, and according to the standards for electronic still cameras, the luminance signal is frequency-modulated with a sync chip level of 6Mtz and a depiercing of 1.5MHz. This is 7MHz
This is because it can be represented by a single frequency signal. In addition, the audio domain signal is generally time-compressed and recorded in the guard band, and the time-compressed signal is frequency modulated with the center carrier frequency around 6MHz.
This is because it can be represented by a single frequency signal of z.

Experiment 1> The relationship between the recording current and the deterioration of the first information was determined by experiment by changing the recording current of the guard band magnetic head. Table 1 shows the measurement conditions.

Table 1 First, as shown in FIG. 3 (al), a single frequency signal of 7 MHz is recorded on the main track 2 by, for example, the inner main track magnetic head 7 of the composite magnetic head 6.The recording current at this time I1.ll is IW1 = 50 mA,
, -p and the optimum recording current. Next, assuming an overlap amount of 30 μm as the worst case of off-track, the composite magnetic head 6 is set to 30 μm as shown in FIG. 3(b).
m Move to the inner circumference side and use the guard band history head 9 to move to area 5.
A single frequency signal of 6 MHz is recorded.

After guard band recording has been performed, the signal in area 5 is reproduced with guard band magnetic head 9 without moving composite magnetic head 6 in the state shown in FIG. 3(b), and its C/N is measured. However, C is a 6 MHz signal and N is a 5 MHz noise.

This C/N is expressed as (C/N).

Next, as shown in FIG. 3(c), the composite magnetic head 6 is moved 30 μm toward the outer circumferential side and returned to the same position as shown in FIG. 3(R), and the magnetic head 7 reproduces the signal of the main track 2.
Measure the C/N. However, C is a 7MHz signal, N
is a 6MHz noise. This C/N (C/N)
It is written as.

The above measurements were performed on the recording current I1 of the guard band magnetic head 9. +2 was varied from 50 mA, - to Ion in the range of -2. The results are shown in FIG. From the same figure, even if the maximum off-track amount is 30 μm, Il and l□ are 20
mAp-, to 40 mAP-, (
C/N) l and (C/N) 2 each 48dB.

At 45 dB or more, it can be seen that even when an image signal requiring a high C/N is recorded on both the main track and the guard band, it can be recorded with practically good image quality.

I,, = 20 mA, -.

In this case, the magnetomotive force of the guard band magnetic head 9 is 40% of that of the main track magnetic head 7.8, and Il, l
, =40 m The magnetomotive force of the magnetic head 9 in the case of AP-p is 80% of that of the main track magnetic head 7°8.

Furthermore, as can be seen from Fig. 1, Il, +2 is 2 S m
AP-.

If it is below, the (C/N) will be 50 dB or more, which is suitable for even higher quality recording. Therefore, the magnetomotive force of the guard band magnetic head 9 is more preferably in the range of 40% to 50% of that of the main track magnetic head 7.8.

Experiment 2 Next, the relationship between the amount of overlap and information deterioration was determined through experiments by varying the amount of overlap. The measurement conditions and method were as follows: the amount of overlap was changed, the recording current 1lJ2 of the guard band magnetic head 9 was changed to 50m,
Everything was the same as in Experiment 1, except that there were two points, 25 mAp-P and 25 mAp-P.

The experimental results are shown in Figure 2. However, the vertical axis in Figure 2 is based on the case where the overlap is zero (C/N), (
C/N), that is, ΔCC/N].

and Δ(C/N). As can be seen from Figure 2, as the amount of overlap between the guard band magnetic head 9 and the main track increases, the attenuation of (C/N) becomes more significant. The smaller the recording current of the magnetic head 9, the more the attenuation is reduced.The tendency of attenuation with respect to the amount of overlap is the same regardless of the magnitude of the recording current.On the other hand, (C/N) is not affected by the amount of overlap.

To explain the above, in Experiment 1 and Experiment 2, the azimuth angle of the guard band magnetic head 9 was 45 degrees, but the same tendency was observed for other angles, and the magnetomotive force of the magnetic head 9 was used for the main track. 40% of magnetic head 7 or 8
By setting it to 80%, the information on the main track is not significantly degraded and the information can be recorded sufficiently well on the guard band. The azimuth angle of the magnetic head 9 is preferably in the range of about 20 degrees to about 45 degrees, more preferably in the range of about 25 degrees to about 45 degrees.

In addition, in Experiment 1, we assumed that the worst case off-track overlap would be 30 μm, but considering that electronic still camera standards allow floppy disks to expand and contract by ±14 μm, the worst case would be approximately 30 μm overlap. Conceivable.

In addition, in Experiment 1 and Experiment 2, the main track was 6.
0 μm 1 guard band is 40 μm, but there is a similar tendency with widths other than these, and the magnetomotive force of the guard band magnetic head 9 is applied to the main track magnetic head 7 or 80.
By setting it between 40% and 80%, you can record information in the guard band well enough without deteriorating the main track information too much.

<Effects of the Invention> According to the present invention, the magnetomotive force of the guard band magnetic head is reduced from 40% to 80% of the magnetomotive force of the main track magnetic head.
% range, so even if the guard band magnetic head off-tracks the recorded main track and records another piece of information overlapping part of it, the information recorded on the main track will not deteriorate much. Moreover, the predetermined information can be recorded sufficiently well on the guard base.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing how the C/N of main track information and the C/N of guard band information change when the recording current of the guard band magnetic head is changed. Figure 2 shows the C/N of the main track information and the C/N of the guard band information when the overlap flight is changed.
FIG. 3 is a characteristic diagram showing how /N changes. FIG. 3 is a diagram illustrating an experimental measurement method for obtaining the characteristics shown in FIGS. 1 and 2. FIG. 4 is a front view showing the ms plane of the magnetic head used in the experiment. FIG. S is an explanatory diagram showing a state in which different information is recorded overlapping a part of the main track. In the drawing, 1 is a magnetic disk (floppy disk), 2
1 is the main track, 3 is the overlap area, 4 is the guard band, 5 is the area where information is recorded by the guard band magnetic head, 6 is the composite magnetic head, 7 and 8 are the main track magnetic heads, 9 is the guard band This is a magnetic head for use. Patent applicant: Agent 1 Photographic Film Co., Ltd.

Claims (1)

[Claims] The first information is recorded on the main track of the magnetic disk by a magnetic head with an appropriate recording current, and then the magnetic head having a predetermined azimuth angle applies magnetomotive force to the guard band adjacent to the recorded main track. A magnetic recording method in which second information is recorded in a range of 40% to 80% of the magnetic head.