JPH0255869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital magnetic storage system in which digital data is written to a magnetic storage medium such as a magnetic tape, a magnetic disk, or a magnetic drum using, for example, a thin film magnetic head. The present invention relates to a multi-channel digital storage device.

At present, magnetic heads for writing and reading data on various magnetic storage media are well known, but thin-film magnetic heads in particular have fewer turns than wire-wound magnetic heads, so they are not suitable for reading data onto magnetic tapes, etc. When writing, a large write current of several amperes at maximum is required. However, if such a large write current flows through the thin film magnetic head, the thin film head will be thermally destroyed. Therefore, in the past, the following method was used to prevent the above-mentioned thermal breakdown from occurring.

FIG. 1 shows an explanatory diagram of a data writing method using a thin film magnetic head.

In the figure, 100 means 5 bits of input data.
This is 4/5MNRZI (Modified NRZI) data that has been converted to bits to prevent three or more consecutive 0s.
102 is the waveform of the 4/5MNRZI modulation signal. Note that in 102, T _nio indicates the minimum magnetization reversal interval of the 4/5MNRZI modulation signal. Further, 104 is a write current waveform flowing through a thin film magnetic head (hereinafter simply referred to as a thin film head). Write current 104
At the rising edge of the 4/5MNRZI modulation signal 102, a positive pulse is generated as the 4/5MNRZI modulation signal 102.
A negative pulse is generated at the falling edge of
If there is a 0 bit in the 4/5MNRZI data 100 and the minimum magnetization reversal interval T _nio is further extended, a pulse of the same polarity as the pulse before the 0 bit is generated when the 0 bit occurs. Note that ΔT ₀ indicates the generation period of each pulse. 106 indicates a magnetization pattern written on the magnetic tape by the thin film head.

As described above, the magnetization pattern 1 is printed on the magnetic tape.
Write current 10 to the thin film head to obtain 06
Since the period of the current flowing through the thin film head is limited by passing the current through the thin film head, less heat is generated in the thin film head, and thermal damage to the thin film head is avoided.

By the way, as is well known, the write current of well-known magnetic heads manufactured by processing bulk materials such as ferrite heads is 4/5MNRZI.
To explain with the modulation signal 102, positive and negative currents are flowing during the entire "H" period and the entire "L" period of the 4/5MNRZI modulation signal 102, respectively, and current is constantly flowing through the magnetic head. There is. In this way, the magnetization pattern shown at 106 is formed.

Next, the above description will be explained in more detail with reference to FIGS. 2 and 3.

In FIG. 2, 10 is the thin film head, 12 is the magnetic tape, gl is the gap length of the thin film head, and V is the relative velocity between the thin film head 10 and the magnetic tape 12.

In FIG. 3, reference numeral 108 indicates a single pulse of positive polarity applied to the thin film head 10. In FIG. Reference numeral 110 indicates a write current with a pulse interval T ₀ , 112 indicates a magnetic field generated by the thin film head 12 , and 114 indicates a magnetization pattern written on the magnetic tape 12 .

A positive single pulse current 108 is applied to the thin film head 10.
gl+V・on the magnetic tape 12.
A magnetization pattern with a length of ΔT ₀ is formed.

Here, T ₀ is T ₀・V＜gl＋V・ΔT ₀ (However, ΔT ₀
<T ₀ ), pulse 110a of write current 110 causes 112a and pulse 110b.
112b by pulse 110c, 112 by pulse 110c
c. The pulse 110d produces a magnetic field pattern 112d in the gap g1. Since the overlapping magnetic fields of these magnetic field patterns 112a, 112b, 112c, and 112d are overwritten with each other, the magnetic tape 1
The magnetization pattern written on 2 becomes 114.

That is, the gap length of the thin film head 10 is gl,
When the relative speed between the thin film head 10 and the magnetic tape 12 is V, the pulse interval is T ₀ and the pulse width is ΔT ₀
In order for overwriting to be possible at a write current of , it is sufficient that V·T ₀ <gl+ΔT ₀ ·V holds as described above. That is, it is sufficient that the write current has a pulse interval of T ₀ and a pulse width ΔT ₀ of T ₀ −gl/V<ΔT ₀ <T ₀ .

Next, a case where the above writing method is performed in multi-channel will be described below.

FIG. 4 shows a recording side block of an N-channel multi-channel digital storage/reproduction device. In the figure, the same members as in FIG. 2 are given the same reference numerals, and their explanations will be omitted.

Each modulation circuit 1 is supplied with a clock 116.
4-1, 14-2......14-N has data 11
8-1, 118-2, ......118-N are supplied, and these data 118-1, 118-2
......118-N is modulation circuit 14-1, 14-2
...... 4/5MNRZI modulated by 14-N and modulated signals 102-1, 102-2, 102-N
As write circuits 16-1, 16-2,...1
6-N. Write circuit 16-
Write currents 110-1, 110-2, . . . 110-N from 1, 16-2, . Magnetization patterns for N channels are formed on the magnetic tape 12.

Here, each modulation circuit 14-1, 14-2......
14-N 4/5 shown at 100 in Figure 5
Consider the case where input data corresponding to MNRZI data are supplied simultaneously.

Each modulation circuit 14-1, 14-2,...14-N
When the above input data is simultaneously supplied to , each modulation circuit 14-1, 14-2, .
5MNRZI modulation signals 102-1, 102-2,...
..., 102-N becomes 102 in FIG. These 4/5MNRZI modulation signals 102 are supplied to write circuits 16-1, 16-2, . . . 16-N, respectively. The magnetization change intervals of the 4/5MNRZI modulation signal are T _nio , 2T _nio , and 3T _nio , and the highest frequency _nax of the 4/5MNRZI modulation signal written on the tape _{is nax}
= 1/2T _nio . Therefore, the shortest writing wavelength λ _nio
is λ _nio =V/ _nax =2T _nio ·V. Usually, the gap length gl of the head is selected to be around 1/2 to 1/3 of λ _nio in consideration of gap loss and the like.

Now, thin film heads 10-1, 10-2,
......The gap length gl of 10-N is 1/2λ _nio .
That is, gl=1/2λ _nio =T _nio ·V. gl=
Since T _nio・V, T _nio・V＜gl＋V・ΔT ₀ (∵
V・ΔT ₀ > ₀ ) holds true. From this, if the gap length gl is 1/2λ _nio or more, it is possible to form a magnetization pattern by overwriting as described above for the pulse interval T _n in the write current 110.

Therefore, write circuits 16-1, 16-2,...
..., 16-N, the write current 10 in FIG.
4, a positive polarity pulse and a negative polarity pulse are generated at the rise and fall of the 4/5MNRZI modulation signal 102, respectively.
When the magnetization reversal interval becomes 2T _n or 3T _n due to the presence of a 0 bit in the MNRZI data 100, a pulse of the same polarity as the pulse before the 0 bit is generated when the 0 bit occurs. The method of generating a pulse when the latter 0 bit occurs will be described below. 4/5
Since the MNRZI modulation signal is inverted with respect to 1 of the 4/5MNRZI data 100, the time position when the above 0 bit occurs is positive polarity at the rise and fall of the 4/5MNRZI modulation signal 102, respectively. In the signal that generated pulses and negative polarity pulses, detect whether there is a negative polarity pulse at the timing after T _nio of each positive polarity pulse or 2T _nio based on the rising edge of each positive polarity pulse, and if there is no negative polarity pulse. Insert a positive pulse into. Similarly, based on the falling edge of each negative pulse, it is detected whether or not there is a positive pulse at a timing after T _nio and 2T _nio of each negative pulse, and if there is no pulse, a negative pulse is inserted.

As described above, write circuits 16-1, 1
6-2,……16-N, respectively 4/5
MNRZI modulation signals 102-1, 102-2,...
A bipolar pulse signal with a pulse interval of T _n is generated from the thin film head 10-N and amplified.
1, 10-2, . . . 10-N. The write circuits 16-1, 16-2, . . . , 16-N write the thin film heads 10-1, 10-2, .
...10-N respectively. The write current is set to 110-1, 110-2, ......11 in Fig. 5.
Shown in 0-N.

Therefore, each current waveform 110-1, 110-
At 2,110-N, if the peak value of each pulse current is I ₀ for positive polarity and -I ₀ for negative polarity, then the write current 1 of ±NI ₀ for N channels simultaneously
10 will flow.

Therefore, if more than one write is performed simultaneously on N channels, the current capacity of the device's power supply will be at the maximum ±
It is necessary to secure a capacity that allows a write current to flow by NI ₀ , and as mentioned above, the thin film head 10 has a small number of turns and requires a large current, so the power supply capacity required by the device is very small. It becomes something big.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to reduce the current capacity of the power source of the device.

In order to achieve the above object, the present invention provides a modulation circuit that modulates each of N channels of digital data, a timing circuit that gives a predetermined delay time to each modulated signal, and a predetermined delay time that is output from each timing circuit. The arbitrary pulse interval T and pulse width ΔT of the write current are such that V・T<gl+V・
Convert ΔT into a satisfying write current (where V is the relative velocity of the magnetic head and magnetic medium, and gl is the gap length of the magnetic head), that is, the pulse interval of the write current is T and the pulse width ΔT is T
At least one of the write currents is generated at a different timing from the other write currents by a write circuit that converts the write current into a write current with −gl/V<ΔT<T and outputs it to each magnetic head. This reduces the current capacity of the device's power supply.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 6 is a block diagram showing a preferred embodiment of the present invention. In the figure, the same members as those in FIG.

The characteristic feature of this embodiment is that each modulation circuit 1
N timing circuits 18-1, 18-2, . . . are provided between the write circuits 16-1, 16-2, .
...18-N is connected.

Each timing circuit 18-1, 18-2,...
18-N are modulated signals 102 supplied to each
-1, 102-2, ......102-N timing is sequentially delayed by ΔT ₀ = T _nio /N signal 12
0-1, 120-2, . . . 120-N can be output.

A preferred embodiment of the present invention has the above configuration,
The effect will be explained below.

Now, the gap length GL of the thin film head is the same as the conventional example.
gl=1/2λ _nio = T _nio・V, modulation circuit 14-1, 1
Let us consider the case where input data corresponding to the 4/5MNRZI data 100 in FIG. 5 are simultaneously supplied to 4-2 and 14-N.

When the above input data is simultaneously supplied to the modulators 14-1, 14-2, . . . 14-N, each modulation signal 102- of each modulation circuit 14-1, 14-2, . 1,102-2,...102-N
becomes the signal 102 in FIGS. 5 and 7.

Each of the above modulated signals 102-1, 102-2,...
..., 102-N are respective timing circuits 18-
1, 18-2, . . . 18-N. Timing circuits 18-1, 18-2, 18-3,...
..., 18-N (18-3 not shown) respectively input the input signals as 0, ΔT ₀ , 2ΔT ₀ , ......(1-N)
It consists of a delay circuit that delays by ΔT ₀ .
Therefore, each timing circuit 18-1, 18-
Modulated signals 102-1, 102-2, 102- respectively supplied to 2, 18-3, ...... 18-N
3,...102-N (102-3 is not shown)
are respectively 0, ΔT ₀ , 2ΔT ₀ ......, (1-N)
Output is delayed by ΔT ₀ . Here ΔT ₀ is
Set T _nio to T _nio /N, which is obtained by equally dividing T nio by the number of channels N. Each timing circuit 18-1, 18-2,...
The timing of the signals output from . . . , 18-N is sequentially shifted by ΔT ₀ , and this is
0-1, 120-2, ......, 120-N. Timing circuit output signal 120-1, 120
-2, . . . 120-N are respectively supplied to write circuits 16-1, 16-2, . . . , 16-N.

Write circuit 16-1, 16-2, ......, 1
6-N, 4/5MNRZI modulation signals 102-1, 102-2, ......102- are respectively input.
For N, the pulse interval is changed in exactly the same way as in the conventional example.
A bipolar pulse signal of T _n is created and amplified,
Thin film head 10-1, 10-2, ......, 10-
supplied to N. Write circuit 16-1, 16-
2,...16-N respectively thin film head 1
The write currents flowing through 0-1, 10-2, ......10-N are expressed as 110-1, 110-2,
......, shown in 110-N. Here, the pulse width ΔT ₀ is set to T _nio /N obtained by dividing the pulse interval T _nio into N equal parts, that is, ΔT ₀ =T _nio /N. Here, the gap length gl is gl=1/2λ _nio =T _nio・V, so T _nio・V
<gl+V·ΔT ₀ (∵V·ΔT ₀ > ₀ ) holds, and overwriting is possible with respect to the pulse interval T _nio . From this, if the gap length gl is 1/2λ _nio or larger, each write current is 110-1,110
-2,...,110-N pulse intervals are all
Since it is T _nio , it is possible to form a magnetization pattern by overwriting, and the thin film heads 10-1, 10-2,
......, 10-N, a continuous desired magnetization pattern is formed on the magnetic tape 12 for N channels.

As is clear from FIG. 7, each thin film head 10-
Write current 110-1, 110-2, 110-N flowing through 1, 10-2, 10-N
do not overlap, the current capacity of the power supply is equal to ±I ₀ and the current capacity for one channel, and will never exceed ±I ₀ .

Next, the modulation circuits 14-1, 14-2,
. . . The case where 14-N is an MFM modulation method, which is different from the above explanation, will be explained.

In FIG. 6, each MFM modulation circuit 14-1,
14-2, input data 118-1 and 118
-2, consider the case where all "1" data in FIG. 8a and all "0" data in FIG. 8b are supplied, respectively. The waveform in Figure 8c is as shown in Figure 8a.
The input data 118-1 of FIG. 8 shows the modulated signal 102-1 modulated by the modulation circuit 14-1, and the waveform in FIG. 8d shows the input data 118-1 of FIG. modulated signal 10
2-2 is shown. And in Figure 8, T
indicates the bit cell length of the data.

As is clear from FIGS. 8c and 8d, all "1" data 118-1 and all "0" data 118-2 are provided in each modulation circuit 14-1 and 14-2.
are supplied and written on the magnetic tape 12, each MFM modulation signal 102-
If the inversion positions of 1,102-2 (FIG. 8c, d) are viewed simultaneously between channels, the minimum inversion interval of the MFM modulated signal is T/2.

Here, each modulation circuit 14-1, 14-2,...
...Data 118-1, 118 in Figure 6 in 14-N
Consider the case where the input data 118 in FIG. 8 are simultaneously supplied as -2, . . . 118-N.

At this time, each modulation circuit 14-1, 14-2,...
...14-N MFM modulation signal output 102-1,
102-2,...102-N is 102 in Figure 8
becomes. Note that in this state, conventionally, the write current was at its maximum at a maximum of ±NI ₀ .

Each of the above MFM modulation signal outputs 102-1, 102
-2, ......, 102-N are timing circuits 18-1, 18-, respectively, as in the above embodiment
2, ..., 18-N, respectively 0,
ΔT ₀ , ......(1-N) ΔT ₀ is delayed and output. The outputs of timing circuits 18-1 and 18-N are shown at 120-1 and 120-N, respectively. Outputs 120-1, 120 of these timing circuits
-2, . . . , 120-N are supplied to write circuits 16-1, 16-2, . . . , 16-N, respectively. In MFM modulation, the input data is inverted at 1 and at the boundary of the 00 bit cell, so the inversion intervals are T, 1.5T, 2T, and T _nio =T.
Therefore, the highest frequency _nax of the MFM modulation signal written on the tape is _nax = 1/2T _nio = 1/2T, and the shortest writing wavelength λ _nio is λ _nio = V/ _nax = 2T _nio・V
=2T・V. Here, the gap length gl of the thin film head is the same as in the previous embodiment gl=1/2λ _nio =T _nio・V=
When T・V, T・V＜gl＋ΔT ₀・V(∵
ΔT ₀ ·V> ₀ ) holds true. From this, if the gap length gl is 1/2λ _nio or more, overwriting is possible with respect to the write current pulse interval T _nio =T. Of course, overwriting is possible for pulse intervals smaller than T _nio =T.

Therefore, write circuits 16-1, 16-2,...
16-N, as mentioned above, generates a positive pulse and a negative pulse at the rise and fall of the modulation signal (in this case, the MFM modulation signal), respectively, and then uses the rise of each positive pulse as a reference. If there is no negative pulse at a timing T time after each positive pulse, a positive pulse is inserted. Similarly, if there is no positive pulse at a timing T time after each negative pulse with reference to the falling edge of each negative pulse, a negative pulse is inserted. Write circuit 16-1, 16-
2, .
1, 10-2, . . . , 10-N to cause a write current to flow. 8e and f, write circuits 16-1 and 16-N write to the thin film head 10.
-1 and 10-N are shown. There are two types of pulse intervals for each write current: T and T/2, and the minimum pulse interval is T/2=T _nio /2.

As described above, the minimum interval between write current pulses of the MFM modulation signal of the channel itself is T/2=T _nio /2. On the other hand, the minimum interval between MFM modulated signals when channels are viewed simultaneously is also T/2=T _nio /2, as described above. What is important here is that in order to prevent the write currents of N channels from overlapping, regardless of the modulation method, the minimum inversion interval of the modulation signal when looking at the channels at the same time, and the write current of the channels themselves The smaller value of the minimum pulse interval (this is T _A ) is N
The pulse width of each write current is set to the equally divided T _A /N, and the timing circuits 18-1, 18-2,...
..., 18-N delay amount is 0, ΔT ₀ , ..., respectively.
..., (1-N) ΔT ₀ and it is sufficient to set ΔT ₀ = _TA /N. In this example, as described above, when looking at channels simultaneously,
The minimum inversion interval of the MFM modulation signal and the minimum interval of write current pulses of the MFM modulation signal of the channel itself are both T/2 = T _nio /2, so in order to prevent the write currents of N channels from overlapping, each write The current pulse width is set to ΔT ₀ =T/2/N=T _nio /2/N, and the timing circuits 18-1 and 18-
2, ..., 18-N delay amount is 0,
ΔT ₀ , ......, (1-N) ΔT ₀ may be set.

Timing circuits 18-1 and 18-N in FIG.
write currents e and f applied to thin film heads 10-1 and 10-N by write circuits 16-1 and 16-N, respectively, and ΔT ₀ =T/2/N , it can be seen that the write currents of the thin film heads do not overlap.

Next, a case will be described in which the gap length ge is set to gl=λ _nio /4=T _nio /2·V=T/2·V in order to write at a shorter wavelength. In this case, T/2·V<gl+ΔT ₀ ·V (∵ is ΔT ₀ ·V>0). From this, if the gap gl is T _nio /4 or more, overwriting is possible with respect to the write current pulse interval T _nio /2=T/2. As mentioned above, the gap length GL is usually selected around 1/2λ _nio to 1/3λ _nio , so
The above gap length is suitable for writing at shorter wavelengths.

Therefore, write circuits 16-1, 16-2,...
..., 16-N, as mentioned above, a positive polarity pulse and a negative polarity pulse are generated at the rise and fall of the modulation signal (in this case, the MFM modulation signal), respectively, and then each positive polarity pulse is If there is no negative pulse at a timing T/2, T, or 3/2 T after each positive pulse based on the rising edge, a positive pulse is inserted. Similarly, if there is no positive pulse at the timing T/2, T, or 3/2T after each negative pulse based on the falling edge of each negative pulse, a negative pulse is inserted. Write circuit 16-1, 16-2, ......, 16-N
Then, as described above, a bipolar pulse signal is created and amplified, and then sent to the thin film heads 10-1, 10-2, . . .
..., 10-N, and a write current is caused to flow. In FIG. 8g and h, write circuits 16-1 and 16-N write the thin film heads 10-1 and 10-N.
shows the write current applied to the The minimum pulse interval for each write current is T/2=T _nio /2.

In the case of this embodiment as well, the minimum inversion interval in the MFM modulation signal when looking at the channels at the same time and the minimum interval between the write current pulses of the MFM modulation signal in the channels themselves are both T/2 = T _nio /2. be. Therefore, in order to prevent the write currents of N channels from overlapping, the pulse width of each write current is set to T/2/N=T _nio /2/N, and the timing circuits 18-1, 18-2, The delay amount of ......, 18-N is respectively 0, ΔT ₀ , ......, (1-N)
It is sufficient to set ΔT ₀ to ΔT ₀ =T/2/N. FIG. 8 Write currents g and h flowing through the outputs 120-1 and 120-N of the timing circuits 18-1 and 18-N, respectively, and the thin film heads 10-1 and 10-N of FIG. 8, and ΔT ₀ =T/2 /N, it can be seen that the write currents of the thin film heads do not overlap.

The 4/5MNRZI modulation method and the MFM modulation method have been described above using two examples. However, in the write circuit of each channel, the write current can be adjusted to an arbitrary pulse interval T so that the modulation signal can be overwritten. On the other hand, in order to convert the pulse width ΔT into a write current such that T-gl/V<ΔT<T and to prevent the write currents of N channels from overlapping, it is necessary to The smaller of the minimum inversion interval of the modulation signal and the minimum interval of pulses of the write current of the channel itself, or if the above minimum inversion interval and the above minimum pulse interval are the same value, divide that value into N equal parts. Set the value as the pulse width of each write current, and set the delay amount of the timing circuits 18-1, 18-2, 18-N to 0, ΔT ₀ , ......, (1-N) ΔT ₀ respectively _. is set to the same value as the pulse width of the write current. Here, in the case of 4/5MNRZI modulation method, if you look at the channels simultaneously, 4/5
The minimum inversion interval of the MNRZI modulated signal is T _nio (see FIG. 7, 102), which corresponds to the demodulation margin (also called detection window width) of the 4/5 MNRZI modulation method. Next, in the case of the MFM modulation method, when looking at the channels simultaneously, the minimum inversion interval of the MFM modulation signal is T/2, which corresponds to the demodulation margin of the MFM modulation method.

From the above, set the smaller value of the demodulation margin of the modulation method and the minimum interval between pulses of the channel's own write current, or if the demodulation margin and the minimum interval between pulses of the channel's own write current are the same value, The value obtained by dividing the value into N equal parts is set as the pulse width of each write current, and the timing circuit 18
-1, 18-2, ..., 18-N delay amounts are respectively 0, ΔT ₀ , ......, (1-N) ΔT ₀ ΔT ₀
If is set to the same value as the pulse width of the write current, the N-channel write currents do not overlap. If the above-mentioned value divided into N equal parts is expressed as T _A , the pulse width of the write current is T _A /N, and ΔT ₀ =T _A /N.

In the above embodiment, the pulse width of the write current is T _A /N, and the delay amounts of the timing circuits 18-1, 18-2, . . . , 18-N are 0, ΔT ₀ , . . . , respectively.
..., (1-N) ΔT ₀ and ΔT ₀ is set to T _A /N, which is the same as the pulse width of the write current, but in the above embodiment, the timing circuits 18-1, 18-2, . . .
..., 18-N have the same delay amount, and if only the pulse width of the write current is selected as M×T _A /N (N is the number of channels, M is an integer satisfying N-1≧M≧2), at least one The write current is generated at a different timing from other write currents, and the current capacity of the power supply is sufficient for M channels.

Note that in the above embodiment, the timing circuit 1
Even if the delay amount of 8-1, 18-2, ..., 18-N is the same and the write current pulse width is smaller than T _A /N, the write current pulse width is smaller than T _A /N. , and the same effect can be obtained even if the width is different.

Further, in the above embodiment, the write current is shifted for each magnetic head, but the present invention is not limited to this. For example, the pulse width of the write current may be made smaller than T _A /N to Even if the timing circuits are configured to have different delay times and the N-channel write currents do not overlap, the same effect can be achieved, and at least one write current is different from the other write currents. The same effect can be obtained if the two events occur at different timings.

Further, in the above embodiment, the case of a thin film head was explained, but the write current of a well-known magnetic head manufactured by processing a bulk material such as ferrite is the "H" of the modulation signal, as described in the explanation of the conventional example. ” and “L”, positive and negative currents are flowing through the magnetic head, and the current is constantly flowing through the magnetic head. For this reason, when a well-known magnetic head is used in an N-channel multichannel digital storage/reproduction device, there is no problem of thermal damage to the magnetic head, but the current capacity of the power supply is
Channels are required. Therefore, when the above embodiment is applied to a well-known magnetic head, the same effect can be obtained and the current capacity of the power supply can be reduced.

As explained above, according to the present invention, data can be written in multi-channels on magnetic tapes, magnetic disks, magnetic drums, etc. using a thin film head and a well-known magnetic head that require a write current of several hundred mA to several A. When using a magnetic head, the modulator that modulates data and the gap length of each magnetic head are
gl, and when the relative velocity between each magnetic head and the magnetic storage medium is V, each modulation signal can be written with a pulse interval of T and a pulse width ΔT of T-gl/V<ΔT<T, allowing overwriting. At least one write current is generated at a different timing from other write currents by a write circuit that converts the current into a current and outputs it to each of the magnetic heads, and a timing circuit that delays each of the modulation signals. Therefore, it has the advantage that the required current capacity of the power supply can be reduced.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the write operation of a thin film magnetic head, Fig. 2 is an explanatory diagram of the writing state of the thin film head and magnetic tape, Fig. 3 is an explanatory diagram of the writing principle, and Fig. 4 is a diagram of conventional multi-channel digital storage. 5 is a block diagram of the recording side of the device; FIG. 4 is an explanatory diagram of the conventional example; FIG. 6 is a block diagram showing a preferred embodiment of the multi-channel digital storage device according to the present invention; FIGS. The figure is an explanatory view of the operation of the embodiment of FIG. 6, and the same members in each figure are given the same reference numerals, 10 is a thin film magnetic head, 12 is a magnetic tape,
14 is a modulation circuit, 16 is a write circuit, and 18 is a timing circuit.

Claims (1)

[Scope of Claims] 1. In a multichannel digital magnetic storage device that forms a plurality of recording tracks on a magnetic storage medium, a plurality of magnetic heads provided corresponding to each of the recording tracks; a modulation circuit that modulates each of a plurality of digital data, a plurality of timing circuits that give a predetermined amount of delay time to each of the modulation signals, a gap length g1 of each of the magnetic heads, and a relative relationship between each of the magnetic heads and the magnetic storage medium. When the speed is V, each modulation signal given a predetermined delay time output from each of the above timing circuits is applied to a write current with a pulse interval of T and a pulse width ΔT of T-g1/V<ΔT<T. A multi-channel digital device comprising a write circuit for converting and outputting the converted magnetic head to each of the magnetic heads, and generating at least one of the write currents at a different timing from other write currents. Magnetic storage device. 2 When the number of multiple magnetic heads is N, the pulse width of the write current is the smaller value of the demodulation margin of the modulation method and the minimum interval of the write current pulses, and if they are the same, the value is N. 2. The multi-channel digital magnetic storage device according to claim 1, wherein the modulated signal is sequentially delayed by the pulse width value.