JPS59207010A - magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The industrial field of application is a multi-channel digital magnetic recording and reproducing device that writes digital data onto a magnetic recording medium such as a magnetic tape, magnetic disk, or magnetic drum using a multi-track magnetic head. Regarding.

Conventional Structure and Problems In order to write on a digital recording medium, a magnetic head has conventionally been driven with a recording current waveform that is the same as the digital waveform. In recent years, a multi-track magnetic head called a thin-film 1-ki head, which is typical of the commercial world, has been developed and is being put into practical use.However, this thin-film magnetic head has fewer turns than conventional bulk heads, so the recording current value is low. needs to be made larger.

In addition, since the degree of bond is large, the tarost difference between tracks is d. Furthermore, it has high nitrification which increases recording density.
There are many types of magnetic flux reversal intervals ranging from short ones to long ones, and the peak position of the reproduction 1 to judge the information P1" and O" is the g where the magnetic flux reversal density is high.
This results in a peak shift that is pushed toward the lower part from the B minute.

In order to suppress the peak shift, a method has conventionally been adopted in which a correction is added to the conventional method of driving the recording head. The first example of this correction method is shown in FIG.

(A) is digital data, and CB) is an MFM-modulated modulation waveform for that data. The peak softness is the lower part of the magnetic flux reversal density, that is, (
B) Level reversal occurs in the form of being pushed from the short part to the long part. This is indicated by the hourglass shape indicated by the broken line D1 in FIG. Therefore, the inversion value tki''z of the short level inversion interval adjacent to the long level inversion interval part of the modulation drum shape is shifted to the opposite side of the peak shift as shown in 1. As a result, the real i D2 The peak position will be reproduced correctly as shown in .

A second example of the mljl square is shown in FIG. 2 ('7) to (-C).

(E) is digital data, and (F) is an MFM-modulated modulation waveform for that data. Utilizing the above-mentioned tendency of peak soft occurrence, two adjacent level inversions like (0) are placed in the center of the long part of the level inversion interval, causing a peak shift and placing the information peak in the correct position. shift until The result is shown by the solid line H2.

Although it is sufficient to drive the recording head with the above correction height, in the case of a thin film magnetic head, it is necessary to increase the recording current value. If the recording current value is increased with the above waveform, the power consumption in the head resistor will increase, the increase in crystallinity of the head sound 1) will increase, and this will lead to thermal destruction. Therefore, in the past, for example, the following method was used to prevent the modulation drum shape subjected to MFM modulation from causing thermal damage.

FIG. 3 (7) to 3) show a method of recording data using a film-forming magnetic head.

(1) is digital data, and (J)) is a modulation waveform that has been subjected to MFM transformation for that data. In the conventional method, the same recording current waveform as the modulation waveform of (J) was written on the recording medium using the direct method, but with a thin film magnetic head, the amplitude of the recording current must be large.
Since there is no head, the amount of power consumed by the head increases, and the heat generated by the head becomes a problem. Therefore, the head is driven by the recording current waveform of (K) or the recording current waveform of (L) with respect to the modulation waveform of (J), and de1 writing to the medium is performed as described in i. (This is called the pulse train recording undercurrent waveform, and the pulse width is t for the pulse repetition period t.
The narrower p is, the less force is required, and the heat generated by the head is reduced. A similar young fruit can be obtained by narrowing the pulse widths t and Q of the recording current waveform shown in (L).

Although head heat generation can be reduced by using the above-mentioned method, multi-trunk 41J, which has multiple heads integrated,
In the case of an Efa head, the recording current is distributed to a plurality of heads at the same time, and a recording current that is twice as large as the number of heads is required. Unfortunately, because multiple heads operate at the same time, crosstalk between trunks during recording becomes particularly large between adjacent tracks.

In order to increase the flow of the recording current at the same time, it has been proposed to use the recording current waveform of (L) and to flow the recording current of (L) by shifting the phase of one modulated word by the pulse width for each track. There is. In this case, the pulse width tq is given by tQ=-, where the number of tracks is N and the data discrimination w in the D key is the wind radius TW.

In the case of the MFM modulation shown in FIG. 3 (Tw=Q.6T), since currents flow in the magnetic nodes of different tracks at different times, the occurrence of crosstalk can also be avoided.

However, in the above method, when the number of tracks increases, that is, when N increases, the pulse width tQ
becomes narrower, making it impossible to record in accordance with the modulated waveform.

'There is dirt. In addition, when the modulation waveform is adjusted as shown in FIG. 1 or 2 in order to perform high-density recording, tracks in which pulses are generated simultaneously are generated. For this reason, the track aN is controlled) 1 (or crosstalk occurs, making it unsuitable for dense recording.And to make the phase different across all tracks, it is necessary to A circuit for setting timing is required, which complicates the circuit configuration.Crosstalk is a major problem between 14 adjacent tracks, and there is no need to shift the timing at which the recording current flows across all tracks.

Purpose of invention 4X Genmei is electrolytic corrosion necessary for recording? The purpose of the present invention is to achieve a reduction in transmission noise, a reduction in crosstalk between adjacent tracks, and suppression of peak shift.

PURCHASE OF THE INVENTION The present invention has a plurality of modulation (B) paths for changing digital data, and a level inversion interval of each modulation signal from each modulation circuit is written and counted in pulses 1 for creating one word. ,
The number of pulses of the write signal is determined corresponding to the level inversion interval of the modulation signal, and a plurality of pulses are converted into a write signal consisting of a predetermined width and a predetermined number of pulses of direct current, and a peak shift is suppressed. It has a write circuit and a thin film magnetic head having multiple tracks for writing each write signal onto a recording medium, and the multiple tracks are all divided into multiple groups, and the writing has as many different phases as the number of groups. 11tfi the JlJ path that generates the pulse signal for signal creation.
D. One writing word of the same phase is given to the heads of tracks in the L river group, and pulse waves for creating one writing word of different phases are given to the heads of tracks of different groups. By inclining the phase of the write signal, pulse currents of the write signals of the heads of trunks of different groups are prevented from being generated simultaneously, and peak shifts are suppressed.

DESCRIPTION OF THE EMBODIMENTS FIGS. 4 and 7 are block diagrams of the recording system of a magnetic recording and reproducing apparatus according to an embodiment of the invention, and FIGS. 5 and 6 are waveform diagrams of each part thereof. I will explain.

From the magnetic head 3-1 to the magnetic head 3-N, set N1 to M (M<N)
+ Divide into solid groups. In this grouping, magnetic heads in the same group are separated so that they do not overlap. That is, the head of each group is s−(
Mxi-1)+1)+3(MX(11)
+ 2) + ... 3-(MX (i-1) ten tan) is divided into Ml-solid dallepe. (
However, 1 is a positive integer) The data corresponding to each of the N low-temperature heads is 1t1, where the modulation clock and data are input.
2+-...1-H modulation circuit converts the signal into a modulation signal necessary for recording on a recording medium. In the non-implemented example, the MFM modulation is old, so for example, Fig.
Modulation 1 for data combed by lJ by 1+(tsu)6-2
The words are as shown in (a)Ryo-12 and (ni)Ryo-2. Conventionally, this modulation signal waveform was
The correction shown in Box 2 of Figure 1 was applied and amplified to send a write current to the magnetic head, but as shown in the conventional example, head heat generation and crosstalk were serious problems. Become. Therefore, the modulation signal waveform is converted into a pulse train write current waveform in the write (b) path to make the pulse phase different, and the level inversion interval of the modulation signal is counted by the pulse train creation pulse signal, and the level of the modulation No. 100 is The background noise is reduced and the peak shift is suppressed in accordance with the inversion interval.

In the pulse generation circuit 4, pulse signals 5-1, 5-2, . ...generates a river s-M. Here, the repetition period of each pulse word is set to be an integer fraction of the data window ll@Tw during demodulation, and is set to be an integer fraction of the time interval required for peak shift suppression. In the embodiment shown in FIG. 5, the pulses 4tp of the pulse signal are set to Tw so that M pulses do not overlap. That is, tp is set so that t'p
The pulse signals 6-1, 5-2, . . . 5-M created in the write circuit 2-(MX (11)+
1), 2 (MX (i 1) +2)+...
...Input to 2-(MX (i-1) +M).

Let's save here! The l path is expressed by a general formula with 1 as a variable. For example, in the case of M==3, the pulse signal et al-1 will be applied to the write circuit 2-1.2-4, and the pulse signal 5-2 will be applied to the write circuit 2-2.2-5. . In the circuit, the level reversal interval of the modulation number 1g is counted using the manually inputted modulation (G waveform and pulse signal), and 2T and T are ・4 at the level reversal interval of the modulation number 100.
In the case of contact, the number of pulses of the same polarity of the pulse train write current for T is reduced by the number necessary for peak shift suppression, and the number of pulses of the same polarity of the pulse train write current for 2T is increased by the number of pulses, Create a pulse train write current.

The operation of the write circuit will be explained using FIG. 6, which is a waveform diagram of each part, and FIG. 7, which is a block diagram. Modulation signal 7
-1 is supplied to the count start pulse generation circuit 16, and is a command 1 word 9- for counting pulse 1 stroke number 5-1.
1 is created. The level reversal interval counting detection circuit 1γ starts counting by the count start pulse 9-1.
The level reversal interval is detected by the operation shown below.
Output a and 1O-1b. Level reversal interval detection 1
When the count start pulse is consecutive T (pulse signal period x 6) and 2T (pulse signal period x 12), that is, when the pulse count value is held as 6 and then as 12. The level inversion interval detection signal 1O-1b is output when the count start pulse is 21"ν T
It is output when 12 is held in the pulse count value and then 6 is held in the pulse count value. The level inversion interval detection signal 1O-1b is delayed by seven pulse signal periods by the delay circuit 18 to obtain a signal 11-1. 1O-1
a and 11-11. (It is input to the OR gate 19 and is logically summed to create a correction pulse 12-1. In order to tie the correction pulse and the modulation 1 word, the modulation signal
The optical delay circuit 15 modulates the pulse signal period to 13
A delayed modulation signal 13-1 is created by delaying the signal twice as long. An exclusive OR gate 2o performs an exclusive OR operation on the delay modulation signal 13-1 and the correction pulse 12-1 to generate a pulse train write current control signal f signal 14-1. Pulse signal 5-1 and pulse train write current control signal 14
-1 is used to create a pulse train τν and a writing current in the writing 1 miya number creation circuit 21. In the write signal generation path, when the pulse train write current control side 1100 No. 14-1 is at the h-gh level, the number of pulses is increased in the direction of the lE pole, and when it is at the low level, the negative pole is Amplify in the direction. As a result, a pulse train drawing current 8-1 is obtained. The write current has the peak shift suppressing effect shown in FIG. 1 because the polarity change position of the pulse moves in a direction that suppresses the peak shift.

A write current indicated by 8-1 is supplied to the magnetic head 3-1 by the pulse number 5-1 from the pulse generation circuit 4 by the write circuit 2-1 as described above. The magnetic head 3-2 adjacent to the magnetic head 3-1 has a modulation 1 word 7-2 corresponding to the input data 6-2 and a magnetic head 3-2.
The write current indicated by 8-2 created as described above is supplied by the write circuit 2-2 by the pulse signal 5-2 which is in a different group from that of 1 and has a different phase.

With this configuration, (M-
1) Since no write current flows through all the magnetic heads at the same time, the write current is seven times as large as when N magnetic heads operate at the same time.

And, since the circumscribed tracks do not operate at the same time, crosstalk occurs only between (M-1) separated tracks, but crosstalk decreases as the distance between heads increases, so crosstalk is reduced. That will happen. Trench modulation can implement peak shift pressure by counting the level reversal interval of the signal and increasing or decreasing the number of polarity pulses of the pulse train write current.

Instead of shifting the phase of the modulation number 1 of each track, we created a pulse signal for creating a write current with a different phase, and the phase of the write DC was made different, and the polarity of the polarity was changed. Since the level inversion position of the write signal is determined by increasing or decreasing the number of pulses, that is, by using the pulse of the pulse signal as a unit, the write current of different groups (magnetic heads) can be simultaneously set to prevent peak shift suppression. There is no flow, and there is no need to provide a delay circuit to set the timing for each magnetic head, simplifying the circuit configuration.

Next, a second embodiment of the present invention will be described with reference to FIGS. 8 and 11 showing block diagrams of the recording system, and FIGS. 9 and 10 showing hourglass diagrams of each part thereof. (The N magnetic heads 3-1 to 3-N are divided into two groups: even-numbered stones and round-numbered stones. The data corresponding to each magnetic head is stored in the modulation circuit 1-1 in the same way as above. . . 1-N, and the write circuit 23-1. . . . 23
-N is supplied. The non-example also uses MFM modulation. A pulse signal for creating a pulse train write current waveform is generated in the pulse generation circuit 24. The repetition period of the pulse signal is the data window width T during demodulation.
It is set to be an integer fraction of w, and is set to be an integer fraction of the time interval required for peak shift suppression.

w In the non-example, the repetition period is set to -, and the pulse duty is set to 50. The pulse 1 word 25-1 from the pulse generation circuit 24 is supplied to the write circuit corresponding to the odd-numbered magnetic head, and the pulse signal 25-2, which is an inversion of this pulse 1 word 26-1, is supplied to the even-numbered magnetic head. The signal is supplied to a write circuit corresponding to the head. In the write circuit, the level inversion interval of one modulation word is counted based on the input modulation one word waveform and the pulse signal, and when the level inversion interval of the modulation signal is 2T, the pulse train write current is continuous for 2T. Reverse the polarity of the pulse located in the middle of the pulse to create a -C pulse train write DC.

The operation of the write circuit will be explained using FIG. 10, which is a waveform diagram of each part, and FIG. 11, which is a block diagram. Modulation 1
The word 7-1 is supplied to the count start pulse generation circuit 32, and a command signal 27-1 for counting the pulse signal 25-1 is generated. Level reversal interval counting detection circuit 3
3 starts counting with a count start pulse 27-1, and when the count reaches the total, outputs a level inversion interval detection signal 28-1. In the case of an MFM modulated signal, the level inversion interval is T,1
．． There are three types, 5T and 2T, and the number of pulses between them is 11 and 6.9.12, respectively, and the above count value 1.
1 means that it has been detected that the level inversion interval is 2T. The nil Ne level inversion interval detection signal 28-1 is used as a correction pulse to invert the 17-character of the pulse located at the center of the pulse train of the pulse train write current for the level inversion interval 2T. For this purpose, the modulation signal 29-1 is changed to a delay of 5 times the pulse signal period by the tl circuit 1, and a delayed modulation signal 29-1 is created, and a level inversion interval detection signal (correction pulse) is generated. Take the timing with 28-1. Delayed modulation signal 29-
1 and the correction pulse 28-1 in an exclusive OR gate 34 to create a pulse train write DC control signal 30-1. A pulse train write current is created in the write signal creation circuit 21 using the pulse 1 word 25-1 and the pulse train write current control signal 3o-1. In the nuclear write signal generation circuit, when the pulse train write DC control signal 30-1 is at High level, the pulse signal is amplified in the positive direction, and the L
When it is at the OW level, it is amplified in the negative direction. As a result, a pulse train write current 26-1 is obtained. Since the write current changes the polarity of a small number (two in the non-example) of pulses at the center of the portion where the level inversion interval is long, it has the peak shift suppressing effect shown in FIG. 2.

A write direct current indicated by 26-1 is supplied to the magnetic head 3-1 by the write circuit 23-1 as described above in response to the pulse signal 26-1 from the pulse generating circuit 24. In the magnetic head 3-2, when no current flows through the adjacent magnetic heads 3-1, 3-3, the write current becomes a write current as shown by 26-2 (%, 26-2).

With this configuration, 11B on both sides of the magnetic head
Since the write current no longer flows through the memory head at the same time, the write current becomes A compared to the case where the N line moves by 1 at the time of one line. Most of the crosstalk is from adjacent tracks, and since the adjacent tracks do not operate at 101, crosstalk is reduced. Sword modulation 1
To perform peak shift suppression by counting the level inversion intervals of words and inverting the 1"11 circle of a small number of pulses in the center of the pulse train of the pulse train feeding current corresponding to the long level inversion intervals. It is possible to change the position of the modulation signal of each track by writing in the company's style without actually measuring it. 1. The phase of the write current is made different by using the pulse store name obtained by the process, and the level inversion position of the write No. 1u is completely determined using the pulse of the pulse No. 1 as a unit. ,
The injected currents of different groups of magnetic heads do not flow at the same time due to correction for peak soft suppression, and there is no need to provide a delay circuit to set the timing for each magnetic head [Simple jo path configuration] becomes.

The write circuit having the configuration of the second embodiment can be applied to the first embodiment, and the write circuit of the first embodiment can be applied to the second embodiment.
It goes without saying that this method can be applied to actual field examples.

In either embodiment, the recorded data is recorded as a known frame structure as shown in FIG.

Next, an example of a reproducing system of a magnetic recording/reproducing apparatus according to the present invention will be shown. The reproduced signal from the gelatinization head is converted into a digital modulation waveform by an amplifier circuit and a waveform shaping circuit, and reproduced data and a reproduced clock are obtained from the waveform by a demodulation circuit. supplying the reproduced data, 1''] raw click to a memory circuit;
Absorbs jitter in playback data and aligns timing.

The configuration example of the memory circuit for timing alignment is shown in the first example.
It is shown in Figure 5. This FIG. 13 shows the structure of the memory provided corresponding to the playback signal outputted from each track. 37-a, 37-b, 37-C of J
The write clock supplied during the period of 7J<High level and 38-2L, 38-b, 38-
It is driven by the read clock supplied during the High level Wj indicated by c. Here, in FIG. 14, only the track of the reference phase (zero) of the 1u write-in pulse is shown.

The playback data from each track is shown in frame memo 1J35-A, 35-B, 35-C for each frame shown in Figure 12.
are sequentially written by the regenerated clock. ■The timing of reading is 37 for the J2 frame memories 35-A, 35-B, and 35-C shown in FIG.
-a, 37-b, 37-c. NW export of data from frame memory is at write timing 3
7-a, 37-b, 37-C, 38-a, 38-
b, 38-c and T.

Timing control of reading and loading is performed by a control path 36.

When each head of each track of the recording head and the reproducing head is configured in-line, when Ichinomiya recorded in the above method is reproduced, the reproduced signal of each trunk is determined by the phase difference of the pulse phase. There is a phase difference between them. Therefore, between the four tangent tracks, the write timing to each frame memory is shifted by this pulse phase difference. In the second embodiment described above, this phase difference is Tw/3. The phase difference across all tracks does not exceed M times the phase difference between adjacent tracks, that is, does not exceed one data period.

To match the phase of data between each track,
In order to correct the phase shift of each track, a different one-bit number (M-1) of soft registers may be provided, but as shown in FIGS. Phase matching can be performed using frame memory.

In this case, 1 is frame memory 16-A, 15-B.
The write clocks of 11F and 15-C- are generated from the reproduced clock and are shifted between the tracks recorded by the M group heads, but the read clock (11F-C- is applied with a common phase to all tracks and has the same timing).
Column data is blue. For this reason, the readout tarokkD
Start typing should be at least out of phase between all trunks.
(M-1) - It is necessary to separate from the end timing of the write clock by at least τ (τ:, 41 is the amount of phase shift between tracks). - Since the number of bits constituting one frame in the crotch is approximately 2o○~400, 1o is appropriate, so the frame memory is If the design is such that the read clock common to all tracks is fully applied after one frame Jvj from the end of one frame writing to Jvj, opening from JQ will not occur.

Effects of the Invention According to the invention, in a recording/reproducing device using a thin-film magnetic head, when writing to a digital boot controller in a multi-channel manner, the increase in density increases the number of channels and the number of magnetic heads for writing. Even in the event of a write error, it is possible to guarantee correct writing to suppress peak softness, and reduce the current required for writing, and crosstalk is also reduced because magnetic heads of adjacent L/ranks do not operate at the same time. can. Furthermore, since the tie ε puffer setting is set by the pulse 1 word generation circuit, there is no need to provide a delay circuit for setting the timing for each magnetic head, so the circuit configuration is extremely simple, and the effect is a dog.

[Brief explanation of drawings]

Figures 1 (a) to 3), Figure 2 (7) to (the slopes are waveform diagrams for explaining the conventional method of correcting peak soft suppression), and Figures 3 (7) to (the slopes are for thin-film magnetic head FIG. 4 is a block diagram of the recording system of an embodiment of the magnetic recording/reproducing apparatus according to the invention, and FIG.
ykJ~ (4 is a waveform diagram for explaining the operation of the same embodiment, Figure 6 is a waveform diagram for explaining the operation of the write circuit used in the same example, and Figure 7 is a waveform diagram for explaining the operation of the write circuit used in the same embodiment FIG. 8 is a block diagram of the recording system of another embodiment of the invention, FIG. 9 (power to tide) is a waveform diagram for explaining the operation of the same embodiment, and FIG. ) to (a) are waveform diagrams for explaining the operation of the write circuit used in the same example, FIG. 11 is a block diagram of the same circuit, and FIG. 12 is a diagram showing the signal configuration of the digital data of the present invention. FIG. 13 is a block diagram showing the configuration of the frame memory, and FIG. 14 (7) to (knob i + -
1: A waveform diagram showing typing of write and i-exit clocks. : J -----'-, - 1-1,・1-Jl ・Soujo ITi circuit 1. ．． '-1
, 2J・°. 3-1. -・・ 3-N ・ Thin mun non 7
circuit.・ ・ ′. -6: ] Figure 1 8 @ Figure 2 Figure 4 8 Begging - Figure 11 Figure 12

Claims (3)

[Claims] (1) A plurality of modulation circuits that modulate digital data, a plurality of write circuits that convert each modulation signal from each of the modulation circuits into a write signal consisting of a pulse stream of a predetermined width, and the storage signal. It has a plurality of magnetic heads for writing on a poisonous air recording medium, and the magnetic heads are
The magnetic heads in the same group are divided into (a positive integer of 2 or more) and arranged so that they do not overlap, and are equipped with a circuit that generates M pulse signals whose phases are mutually different and whose pulse periods do not overlap. , within the same group, when driving the magnetic head with a (bl-phase pulse signal and a different pulse signal for each group), the level inversion interval of one modulation word is counted with the pulse signal, and the modulation signal is 1. A magnetic recording and reproducing apparatus, characterized in that the number of pulses of the same polarity of a write signal is determined in accordance with a level inversion interval of . (2) The number of pulses of the same polarity of the write signal is determined by increasing the number of pulses of the same polarity of the write signal corresponding to the long level inversion interval when the modulation signal has a long and short level inversion interval. 2. The magnetic recording/reproducing apparatus according to claim 1, wherein the setting is made by reducing the number of pulses of the same polarity corresponding to short points. (3) The number of pulses of the same polarity of the write signal is a modulation signal. This is set by inverting the a-polarity of a small number of pulses located in the center of the pulse train of the write signal corresponding to the long level inversion interval of the signal to reduce the number of pulses of the same polarity. The magnetic recording and reproducing device according to scope 1.