JPS6265220A - Head device for magnetic recording and reproduction - Google Patents

Abstract

PURPOSE:To decrease the asymmetry between signals by superposing a DC bias current upon a signal recording current to be flowed to a coil for recording and reproduction when constituting a head device by winding the coil for record ing and reproduction around the 1st side core and a coil for erasure around the 2nd side core while using a center core in common. CONSTITUTION:The 1st side core 1a which has the 1st magnetic gaps 1c across a center core 21 and the 2nd side core 2a which has the 2nd magnetic gaps 2c are provided to constitute a closed magnetic path. Further the coil 6 for recording and reproduction is wound around the core 1a and the erasing coil 7 is wound around the core 2a to constitute the head device. In this constitution, not only a current 20 for signal recording, but also a DC bias current 19 are made to flow through the coil 6 in superposition relation. Consequently, leak magnetic flux is canceled to reduce variation of a recording magnetic field and decrease the asymmetry between signal gaps.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic recording/reproducing head device.

In particular, the present invention relates to a head device suitable for a flexible disk device.

[Conventional technology]

Hereinafter, the head 41crt of a flexible disk device will be explained as an example.

FIG. 8 is a sectional view showing a conventional head device for a flexible disk. In FIG.
1b) are opposed to each other via a first magnetic gap (1C). (2) is the erasing head, and the second side core (2a) and the second center core (2b) are the second magnetic gap (2C).
Opposed via t-. (3) is both heads (1).

(2) It is a non-magnetic material for magnetically separating. 1st
A recording/reproducing coil (6) through which a signal recording current flows is wound around the side core (1a), and an erasing coil (7) through which an erasing DC current flows around the second side core (2a). . The magnetization (5) recorded on the medium (4) by the recording/reproducing head (11) in a width wider than the track width is tunnel erased by the erasing head (2), and the recording remains with the original track width.At this time, Both coils f6) and +7+ of the recording/reproducing head (1) and the erasing head (2) are energized at the same time. Therefore, a non-magnetic material (3) is used to magnetically separate the recording/reproducing head (1) and the erasing head (2).
is required. However, the density of recording continues to increase.

Due to the recording format on the medium, the distance between the recording gap and the erasing gap is required to be small.

On the other hand, in consideration of head miniaturization, productivity, and cost reduction, it goes without saying that it is desirable to eliminate such separation and integrate both heads.

[Problems to be solved by the invention] However, as is the case with the conventional method, both center cores (4b) and (2b
) If the non-magnetic material (3) between the holes is removed, the following problem will occur.

As shown in FIG. 9, an alternating current signal recording mc current flows through the recording/reproducing head 11, and the magnitude of the signal magnetic field changes depending on the relative direction of the current. That is, in FIG. 9 ta), the direction of the DC current flowing through the erasing coil (7) of the erasing head (2) and the direction of the AC current flowing through the recording/reproducing coil (6) of the recording/reproducing head (11) are shown. In this case, the leakage magnetic flux (8) leaking from the erasing head (2) based on the DC current to the recording/reproducing head (11) and the magnetic flux of the recording/reproducing head (1) are In the first side core (1a) of the recording/reproducing head (1), the direction is the same and the signal writing magnetic field increases.On the other hand, as shown in Fig. 9 (bl), the erasing coil of the erasing head (2) (7) The direction of the direct current flowing through.

Recording/playback coil (6) of recording/playback head (1)
When the direction of the alternating current flowing through the two is the same, the direction from the erasing head (2) based on the direct current to the recording/reproducing head (
1) and the leakage magnetic flux (8) leaking to the recording/reproducing head (1).
1's magnetic flux (9) is in the opposite direction in the recording/reproducing head (11's first side core (1a)), and the signal writing magnetic field becomes smaller.

FIG. 10 shows the strength and distribution of the recording magnetic field at the center position of the medium in the case of tbl in FIG. 9(a), obtained by computer simulation using the finite element method.

As is clear from this figure, the distribution and strength of the recording magnetic field are very different in each case. Furthermore, FIG. 11 shows the magnetic field generated by the recording head +11, which was similarly determined by the finite element method computer simulation.1 For example, suppose that the coercive force of the medium is 630 Oersted, and the magnetization is reversed at that value.

1 for the interval of 49 signal recording currents in Fig. 12(a).
The magnetization as shown in FIG. 2(b) remains, and as shown in FIG. 12(tc), the reproduction signal intervals corresponding to the intervals 49 and 2 become asymmetrical. Hereinafter, this phenomenon will be referred to as asymmetry. Such asymmetry of the reproduced signal causes errors in reading recorded information, which is a problem in that it is not desirable from the viewpoint of vortex-tight recording and reliability.

This invention was made to solve the above-mentioned problems, and it is possible to eliminate the magnetic separation of the center core, and also to significantly reduce the asymmetry of the signal spacing when the magnetic separation is removed. The object of the present invention is to obtain a magnetic recording/reproducing head device that can be miniaturized and increased in density.

[Means for solving problems]

A magnetic recording/reproducing head device according to the present invention.

A DC bias current is added to the signal recording current of the recording/external coil so as to cancel the leakage magnetic flux of the erasing coil passing through the first side core.

[Effect]

In this invention, a DC bias current is added to the signal recording current of the recording/reproducing coil so as to cancel the leakage magnetic flux of the erasing coil passing through the first side core, so that the leakage magnetic flux is canceled and the recording magnetic field is The asymmetry of the interval of the Gai signal is reduced when the fluctuation of is small.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. @1
The figure is a cross-sectional configuration diagram illustrating an embodiment of the present invention. 2D is a center core shared by a recording/reproducing core and an erasing core. In addition, the recording/playback coil (
6) is the signal recording current plus the DC bias 'ft current. FIG. 2 is a current waveform diagram used in one embodiment of the present invention, where as is the conventional signal recording current, α
9 is superimposed on the signal recording current αl. That is, the signal recording current used in one embodiment of the present invention is a direct current bias current of 5 to 25 inches, in this case about 10%, of the signal recording current to be applied.

FIG. 3 shows a simple equivalent magnetic circuit for calculating two DC bias currents to be superimposed.

αυ is the magnetic resistance R8 of the center core, α is the magnetic resistance RR of the first side core (1a), and Q3 is the magnetic resistance Rg of the first magnetic gap of the recording/reproducing head (1).

Here, the amount of magnetic flux flowing into the first side core (1a) from the erasing head (2) is equal to the magnetic flux generated from the erasing coil (7). - As an example, calculate the parameters as shown in Figure 4, i.e. l=6m, m-6in*, n-0,6m'D (!: 4-5.92xlO/μo(1,A), R
R,,+R,+R0=6.67X10/μo(1/)(
), and the first side core (
1) The leakage magnetic flux of the erasing coil passing through can be canceled. The clay value determined by the finite element method is also about 11.5%. Therefore, by superimposing a DC bias current of 11.5% of the signal recording current, the recording magnetic field distribution at the center position of the medium is
Figure i@5 and Figure 6 are obtained by computer simulation for both the states in Figures ta) and (b). As described above, the asymmetry of the recording magnetic field can be significantly reduced by the effect of the DC bias current. - As an example, consider the degree of asymmetry, assuming that magnetization is reversed when the coercive force exceeds 6300e.

defined as the inner circumference (r) of a 15-inch flexible disk.
-2&188m) and 8rOObpi (bit pe
NRZ (n
Table 1 shows the values calculated for the 010101 signal (one returnjero).

Table 1 Furthermore, by optimally selecting the value of this DC bias current, it is possible to reduce the degree of asymmetry to almost zero.

Next, FIG. 7 shows the results of actual measurement of the effect of the DC bias current. For this example.

Asymmetry, which was longer than 160+1 seconds (deviation amount) in the absence of a DC bias current, can be eliminated by adding a DC bias current of about 11L, which is about 14% of the signal recording current.

The time could be reduced to about 25+1 seconds. Also from this example.

It is clear that adding a DC bias current of 5 to 25% of the signal recording current to the signal recording current is effective.

〔Effect of the invention〕

As described above, according to the present invention, the leakage magnetic flux of the erasing coil passing through the first side core is canceled.

Since a DC bias current is added to the signal recording current of the recording/reproducing coil, it is possible to significantly reduce the asymmetry of the signal interval when the magnetic separation of the center core is removed. This has the effect that an inexpensive magnetic recording/reproducing head device can be obtained, and a highly reliable magnetic recording/reproducing head device that can be made smaller and higher in density can be obtained.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional configuration diagram of a magnetic recording/reproducing head device according to an embodiment of the present invention, Fig. 2 is a current waveform diagram used in an embodiment of the invention, and Fig. 3 is an embodiment of the invention. FIG. 4 is a cross-sectional configuration diagram of a magnetic recording/reproducing head device used for analysis according to an embodiment of the present invention;
5 is a magnetic field distribution diagram according to an embodiment of the present invention, FIG. 6 is a magnetic field distribution diagram according to an embodiment of the present invention, and FIG. 7 is a DC bias current and asymmetry diagram according to an embodiment of the present invention)
It is an actual measurement diagram showing the relationship of IJ-. Figure 8 is a cross-sectional configuration diagram showing a conventional magnetic recording/reproducing head device, and Figure 9 illustrates the flow of magnetic flux when the non-magnetic material between the center cores is removed in a conventional magnetic recording/reproducing head device. Figure 10. FIG. 11 is a magnetic field distribution diagram in a conventional head device. Figures 12(a), (b), and (c) relate to a conventional head device. (a) is a current waveform diagram of a signal recording current, (b) is a diagram illustrating recording magnetization of a recording medium, and (C) is a diagram illustrating a reproduction signal. (1)...recording/playback head, (1a)...
First side core, (1c)...first magnetic gap, (2)...erasing head. (2a)...Second side core, (2c)...Second magnetic gap. (6)... Recording/reproducing coil, (7)... Erasing coil, Q9... DC bias m current, ■... Signal recording current, Qυ... Center core. Note that the same reference numerals in Figure 9 indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A recording/reproducing head in which a center core and a first side core face each other via a first magnetic gap, and a recording/reproducing coil through which a signal recording current flows is wound around the first side core;
And the above center core is shared and the above center core and the second
The side cores have an erasing head that faces each other through a second magnetic gap and has an erasing coil wound around the second side core through which an erasing DC current flows, and leakage magnetic flux based on the DC current of the erasing coil causes the recording and erasing. In a magnetic recording/reproducing head device that passes through the first side core of the reproducing head, a DC bias current is applied to the signal recording current of the recording/reproducing coil so as to cancel the leakage magnetic flux of the erasing coil that passes through the first side core. A magnetic recording/reproducing head device characterized by adding: (2) The value of the DC bias current is 5 to 2 of the signal recording current.
The magnetic recording/reproducing head device according to claim 1, wherein the magnetic recording/reproducing head device has a size of 5%.