JPS6344308A - Magnetic head - Google Patents

Abstract

PURPOSE:To form symmetrical recording magnetization by supplying recording currents asymmetrically to recording coils divided into two parts and compensating the asymmetry of the recording magnetization by the interference of an erasing magnetic flux with recording magnetic fluxes. CONSTITUTION:Since a current supplying circuit 20 supplies the recording currents asymmetrically to the coils 7, 8, the magnetic energies generated by the coils 7, 8 are different from each other. The recording magnetic flux A' in the same direction as the direction of the erasing magnetic flux E, therefrom, decreases and the recording magnetic flux B' in the direction different therefrom increases. Since the erasing magnetic flux E in the specified direction by an erasing head 2 exists at this time, the magnetic flux A' increases and the magnetic flux B' decreases if the magnetic flux E interferes with the magnetic fluxes A', B'. The interference of the magnetic flux E is thereby eventually cancelled so that the magnetic fluxes A', B' are equal to each other in the directions different from each other. The asymmetry of the recording magnetization is compensated by the interference of the erasing magnetic flux with the recording magnetic fluxes in the above-mentioned manner; therefore, the symmetrical magnetization is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is most suitable for application to a magnetic head for a floppy disk device, for example, and includes a recording head and an eraser disposed close to the recording head. The present invention relates to a magnetic head comprising a head.

[Summary of the invention]

In the present invention, the first coil and the second coil are connected by a center tap.
A recording head that has a recording coil divided into two coils and alternately generates recording magnetic flux in different directions, and an erasing head that is arranged close to this recording head and generates an erasing magnetic flux in a fixed direction. For example, in a magnetic head for a floppy disk device, recording current is supplied asymmetrically to the first coil and the second coil, so that the recording magnetic flux in the same direction as the erasing magnetic flux is transmitted in the same direction as the erasing magnetic flux. By making the recording magnetic flux smaller than the recording magnetic flux in a different direction, it is possible to compensate for the asymmetric recording magnetization caused by the interference of the erasing magnetic flux with the recording magnetic flux, and to make the recording magnetization symmetrical.

[Conventional technology]

Traditionally, magnetic heads for floppy disk drives have been able to reproduce normally (continued) even if there is a misalignment (off-track) between the center of the magnetic head and the center of the recording trunk of the disk.
In order to ensure data compatibility, both sides of a recording track are erased during recording (writing) to ensure a constant gap (guard band) between adjacent recording tracks. And this kind of magnetic head has
There are two types: a tunnel erase head that has an erase gap on both sides behind the recording/playback gap, and a strado) Li' (raze hend) that has an erase gap on both sides of the record/playback gear knob.
A laminate type in which erased cores are laminated on both sides of a recycled core,
There is also a bulk type in which an erasing core is placed adjacent to the rear of a recording/reproducing core.

Therefore, as an example of a conventional magnetic head, the most commonly used tunnel erase head, the halky type, is shown in Figure 7.
This will be explained with reference to FIG.

First, as shown in FIGS. 7 and 8, this magnetic head 1 is composed of a recording/reproducing head 2 and an erasing head 3. As shown in FIGS. A recording/reproducing coil 5 is wound around the recording/reproducing core 4 of the recording/reproducing head 2, and this recording/reproducing coil 5 is connected to a first coil 7 and a second coil by a center tap 6.
The coil 8 is divided into two. These first coils 7
The number of turns of the second coil 8 and the number of turns of the second coil 8 are configured to be equal to each other. At the rear of the recording/reproducing core 4 (backward in the direction of disk movement indicated by arrow a), a thickness of several tens of μm is provided.
Erasing cores 10 are arranged adjacent to each other with a spacer 9 made of glass having a diameter of
1 is wound.

A pair of erase gaps 1 are formed in the erase core 10.
2 are located on both rear sides of the recording/reproducing gap 13 formed in the recording/reproducing core 4. Note that the distance between the gaps 12 and 13 is, for example, about 600 μm. Furthermore, the recording/reproducing core 4 and the erasing core 1O are front cores 4a, 10a and back cores 4b, 10b, respectively.
and the spacers 9 are also the front spacers 9.
a and a back spacer 9b.

In this magnetic head 1, during recording, a recording current is alternately passed from the center tap 6 to the first coil 7 and the second coil 8, and the recording/reproducing core 4 is caused by the magnetomotive force of both coils 7.8. recording magnetic flux A in mutually different directions,
B is generated alternately. and recording/playback gap 13
A recording magnetized recording track 14 (shaded area in FIG. 7) is formed on the disk at a portion. And at the same time as this record,
A DC erasing current is passed through the erasing coil 11, and the magnetomotive force of the erasing coil 11 generates an erasing magnetic flux E in a certain direction in the erasing core 10, so that both sides of the recording track 14 are erased in the erasing gap 12. has been done.

[Problem that the invention seeks to solve]

By the way, one of the important characteristic items of the magnetic herad 1 mentioned above is peak shift. This peak shift is caused by the fact that when only one pulse is written to the disk, the output waveform becomes one independent waveform, but when multiple pulses are written at different intervals, the independent waveforms interfere with each other, resulting in a peak in the composite waveform. This means that the part is shifted from the written position. And the peak shift is DB6 pattern (110110110------
-------1M pattern) and its inverted pattern B6D pattern (101101101----
−・−・−1W pattern) is the worst case and the maximum.

Here, if the recorded waveform is symmetrical, (M peak shift) - (W peak shift).

However, conventionally, the recording current supplied to the first coil 7 and the second coil 8 of the recording/reproducing head 2 is
As shown in the figure, the + side and the example are symmetrical, and Figure 9 (a
), the absolute values of recording magnetic fluxes A and B in different directions become equal. At this time, as shown in FIG. 9(b), since there is an erasing magnetic flux E in a certain direction due to the erase throat 3, this erasing magnetic flux E interferes with the recording magnetic fluxes A and B, and as shown in FIG. ), the recording magnetic flux A in the same direction as the erasing magnetic flux E increases, and the i3 magnetic flux B in the direction different from the erasing magnetic flux E decreases. Therefore, the recording waveform is not symmetrical due to the influence of the erase magnetic flux E during recording, and for example (
M peak shift) < (W peak shift).

On the other hand, in this type of floppy disk device, a data pulse train read by the magnetic head 1 is separated into data and a clock by a data window. At this time, the time margin before and after the read data relative to the width of the data window is called a time margin, and this time margin needs to have a sufficient margin for the peak shift so that there is no read error. However, if the peak shift increases due to the influence of the erase magnetic flux E during recording, it becomes impossible to secure a specified time margin in the W pattern, which is the worst case.

Another important characteristic item of the magnetic head 1 is override, and the difference between this override and peak shift is that if the peak shift is decreased, the override will worsen, and if the override is improved, the peak shift will be decreased. There is an increasing relationship. For this reason, in the past, there was a problem that the peak shift increased due to the influence of the erase magnetic flux E, so that only a magnetic head with good override could be used.

By the way, magnetic heads for floppy disk drives include the aforementioned bulk type, laminate type, and straddle erase head, but direct current erasure is used to asymmetric recording magnetization due to interference of erase magnetic flux with recording magnetic flux. The above problems are unavoidable with any type of magnetic head.

In particular, in the bulk type magnetic head 1 described above, since the recording/reproducing core 4 and the erasing core 10 are arranged adjacent to each other along the direction of magnetic flux, the interference becomes particularly noticeable. Moreover, recently there is a strong demand for lowering the cost of the magnetic head 1, so the back spacer 9b between the back cores 4b and 10b and the front spacer 9a between the front cores 4a and 10a may be omitted, and in this case the interference becomes even more pronounced. become.

Therefore, the present invention aims to compensate for the asymmetric recording magnetization caused by the interference of the erase magnetic flux with the recording magnetic flux, and to make the recorded magnetization symmetrical.

[Means for solving problems]

In the magnetic head described above, the present invention provides a recording current that is asymmetrically supplied to the first coil and the second coil so that the magnetic energies generated by the first coil and the second coil are different from each other. A current supply circuit is provided so that the recording magnetic flux in the same direction as the erasing magnetic flux is smaller than the recording magnetic flux in a direction different from the erasing magnetic flux.

[Effect]

According to the present invention, since the recording current is asymmetrically supplied to the first coil and the second coil, the magnetic energies generated by the first coil and the second coil are different from each other.

As a result, the recording magnetic flux in the same direction as the erasing magnetic flux decreases, and the recording magnetic flux in a direction different from the erasing magnetic flux increases. When erase magnetic flux in a certain direction interferes with these recording magnetic fluxes, the decreased recording magnetic flux increases, and the increased recording magnetic flux decreases.As a result, the interference of the erase magnetic fluxes is canceled, and the erase magnetic fluxes in different directions The recording magnetic flux can be made equal.

〔Example〕

Hereinafter, an embodiment in which the present invention is applied to a magnetic head for a floppy disk device will be described with reference to FIGS. 1 to 6B. The magnetic head of this embodiment is a bulk type tunnel erase head, and the same parts as those of the conventional example explained in the [Prior Art] section are given the same reference numerals and their explanation will be omitted. do. The circuit also shows a simple equivalent circuit when writing.

First, FIG. 1 shows a first embodiment, in which a current supply circuit 20 is provided in a recording/reproducing head 2 of a magnetic head 1. In FIG. This current supply circuit 20 includes resistors 21 and 22 connected in series to the first coil 7 and second coil 8 of the recording/reproducing coil 5, respectively, and a resistor connected in parallel to the recording/reproducing coil 5. 23 and a switching element 24 provided between the resistors 21 and 22.

Here, the resistors 21 and 22 are current limiting resistors that determine the amount of recording current, the resistor 23 is a write damping resistor that determines the rise of the recording current, and the switching element 24 directs the recording current to the first coil 7. and the second coil 8. and resistance 21.22
The value of RA, R.

Then, these are configured such that RA≠R1, and here, for example, RA>Rs. Then, by alternately passing a recording current from the center knob 6 to the first coil 7 and the second coil 8, recording magnetic fluxes A' and B' in different directions are alternately generated in the recording/reproducing core 4. let Simultaneously with this recording, a DC erasing current is passed through the erasing coil 11 to generate an erasing magnetic flux E in a fixed direction in the erasing core 10.

According to the magnetic herad 1 of the first embodiment, since the resistances 21 and 22 of the current supply circuit 20 satisfy RA > RB, the amount of recording current is determined by these resistances 21 and 22, and the second As shown in the figure, the current amount of the recording current is +
The two sides are asymmetrical, and the magnetic energy generated by the first coil 7 is smaller than the magnetic energy generated by the second coil 8. This results in Figure 3 (
As shown in a), the recording magnetic flux A' in the same direction as the erasing magnetic flux E decreases, and the recording magnetic flux B' in a direction different from the erasing magnetic flux E increases. At this time, as shown in FIG. 3(b), since there is an erasing magnetic flux E in a certain direction due to the erasing head 3, if this erasing magnetic flux E interferes with the recording magnetic fluxes A' and B', as shown in FIG. As shown in (C), the recording magnetic flux A' increases and the recording magnetic flux B' decreases. As a result, the interference of the erase magnetic flux E is canceled, and the recording magnetic fluxes A' and B' in different directions become equal.

As mentioned above, the erasing magnetic flux E with respect to the recording magnetic fluxes A' and B'
compensates for the asymmetric recording magnetization caused by the interference of
Peak shift can be reduced. Even if the data pattern is the worst, it is possible to reliably secure a specified time margin by suppressing peak shifts.

Furthermore, by preventing the asymmetric recording magnetization and reducing the peak shift, it becomes possible to use a magnetic head with worse override. In addition, in the magnetic head river of the example, the back spacer 9b between the back cores 4b and 10b
Moreover, even if the front spacer 9a between the front cores 4a and 102 is omitted, the interference of the erasing magnetic flux E can be canceled, so that the cost of the magnetic helad 1 can be reduced.

Next, FIG. 4 shows a second embodiment, in which a current supply circuit 26 is provided in the recording/reproducing head 2 of the magnetic head 1. In FIG. This current supply circuit 26 includes a resistor 29.30 connected in parallel to the recording/reproducing coil 5 via diodes 27, 28 in opposite directions, and a switching element 31.
and a resistor 32. Here resistance 2
9 and 30 are write damping resistors that determine the rise of the recording current, the switching element 31 switches the recording current between the first coil 7 and the second coil 8, and the resistor 32 controls the current of the recording current. It is a current limiting resistor that determines the amount of current. And the resistance of 29.30 is Rc
, RI, these are constructed such that Rc≠R9, and here, for example, Re>RD.

According to the magnetic head 1 of the second embodiment, since the resistance 29.30 of the current supply circuit 26 satisfies RC>RD,
These resistors 29 and 30 determine the rise of the recording current, and as shown in FIG. The energy is smaller than the magnetic energy produced by the second coil 8. As a result, the interference of the erasing magnetic flux E is canceled and the recording magnetic fluxes A' and B' in different directions become equal, as explained in FIGS. 3(a) to 3(c).

Note that even if the circuit portion of resistor 29.30, which is the write damping resistor shown in FIG. 4, is changed to resistor 33.34 or resistor 35.36 as shown in FIG. 6A or 6B, the same operation will occur. can be made to do so. Furthermore, here,
When the value of resistor 33.34 is RE and RF, RC=Rt
, RD = 1/ (1/RE + 1/RF), and if the values of resistor 35.36 are RG and RH, then RC =
1/(1/Rc+1/R□), Ro=RH.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various effective changes can be made based on the technical idea of the present invention.

For example, the magnitudes of the first coil and second coil, as well as the current limiting resistance and write damping resistance shown in the examples are relative, and these may be adjusted as appropriate depending on the direction of the recording current and the direction of the erasing magnetic flux. Be changed. Further, in the embodiment, a bulk type tunnel erase head is shown, but a laminate type or straddle erase head can be similarly applied.

Note that the present invention is not limited to magnetic heads for floppy disk drives, but can be applied to various magnetic heads that record on various magnetic recording media.

〔Effect of the invention〕

According to the present invention, a recording current is asymmetrically supplied to a first coil and a second coil of a recording head for generating recording magnetic flux in different directions, and the recording current is supplied in the same direction as the erasing magnetic flux by the erasing head. Since the recording magnetic flux is made smaller than the recording magnetic flux in a direction different from the direction of the erasing magnetic flux, it is possible to compensate for the asymmetric recording magnetization caused by the interference of the erasing magnetic flux with the recording magnetic flux and make the recorded magnetization symmetrical. .

Therefore, it is possible to prevent an increase in peak shift due to asymmetric recording magnetization and to reduce the peak shift. Even in the worst case of the data pattern, by reducing the peak shift, a specified time margin can be ensured, read errors can be prevented, and recording and reproduction characteristics can be significantly improved.

In addition, by preventing asymmetry of recording magnetization and reducing peak shift, it becomes possible to use magnetic heads with worse override characteristics, which improves the yield of magnetic heads that are selected based on override characteristics and increases the The cost can be reduced.

Furthermore, the present invention does not compensate for the asymmetry of recorded magnetization during reading, nor does it compensate for the absolute value of the peak value during writing, so compatibility with recording media does not become a problem. That is, since the direction of the peak shift can be predicted in advance based on the data pattern, there is a so-called write compensation in which the pattern is shifted in the opposite direction to the shift direction during reading during writing. However, since the correction value of this write compensation remains on the recording medium, for example, if a device that performs write compensation reads data from a recording medium that has not undergone write compensation, there is a high possibility that a read error will occur.

However, according to the present invention, which performs compensation by making the recording current asymmetric, compatibility with the recording medium does not become a problem.

[Brief explanation of the drawing]

1 to 6A show an embodiment in which the present invention is applied to a magnetic head for a floppy disk device, and FIG. 1 is a front view of the main parts of the magnetic head in the first embodiment and its current flow. Supply circuit diagram, Figure 2 is the same recording current waveform diagram as above,
FIG. 3 is an explanatory diagram for explaining compensation for asymmetric recording magnetization, in which (a) is a recording data waveform diagram, (b) is a diagram showing erasing magnetic flux, and (c) is a recording magnetization waveform diagram. be. Fourth
The figure is a front view of the main parts of the magnetic head in the second embodiment and its current supply circuit diagram, Figure 5 is a recording current waveform diagram of the same as above, and Figures 6A and 6B are circuit diagrams of a modification of the same as above. . 7 to 10 show a conventional example of a magnetic head for a floppy disk uiZ, in which FIG. 7 is a plan view of the main parts of the magnetic head, FIG. 8 is a front view of the same, and FIG. is an explanatory diagram for explaining asymmetric recording magnetization, and (a
) is a recording data waveform diagram, (b) is a diagram showing erase magnetic flux, (
C) is a waveform diagram of recording magnetization, and FIG. 10 is a recording current waveform diagram of the same as above. In addition, in the symbols used in the drawings, 1-m-・--Magnetic head 2--・・--------------・-- Recording/reproducing head 3-- ...--Erasing head 5--
・－－－１－－－－・－・－Recording/reproduction coil 6－・・
−・−−−−1−−・−・−Center tap 7−・−・
−1−−−−−−−−−・−First coil 8−−−−−
−−・・−−−−−−First coil 11・−−−
−−−1−−−−・Erasing coil 20.26−・−1−
-------・Current supply circuit 2L22-----1 current limiting resistor 29.30--1-11 write damping abrasive resistor E---1- ·········································−········−·······−······−······−·····−······−·······−···················−···················−
−−−・−−−−−−・Recording magnetic flux.

Claims (1)

[Claims] A recording head having a recording coil divided into a first coil and a second coil by a center tap and alternately generating recording magnetic flux in different directions; and an erase head arranged to generate an erase magnetic flux in a certain direction, the first coil and the second coil are arranged so that the magnetic energies generated by the first coil and the second coil are different from each other. A current supply circuit is provided to supply a recording current asymmetrically to the coil, and the recording magnetic flux in the same direction as the erasing magnetic flux is smaller than the recording magnetic flux in a direction different from the erasing magnetic flux. magnetic head.