JPH01134709A - Magnetic head and its manufacture - Google Patents

Abstract

PURPOSE:To efficiently equalize a waveform by means of a magnetic head itself by providing an auxiliary gap by means of a conductive film formed in the vicinity of the gap. CONSTITUTION:The title head is equipped with cores 1 and 11 in which a magnetic flux corresponding to a current to flow to a coil flows, a first conductive film 3 formed in the vicinity of a gap 20 of the cores 1 and 11, a magnetic film 4 formed between the gap 20 and first conductive film 3, and a second conductive film 13 to prepare a closed loop with the first conductive film 3 and to be formed so that at least one part of the magnetic flux can pass in the closed loop. When the current is made to flow to the coil wound around the core 1, the magnetic flux prepared by an induced current is circulated between magnetic films 4 and 14 and the cores 1 and 11. The magnetic flux outflows from either of the magnetic films 4 and 14 and the cores 1 and 11, and it inflows the other in jumping on the first conductive film 3. A direction in which the magnetic flux flows is made opposite to the direction of the magnetic flux in the gap. Thus, the waveform can be efficiently equalized by the magnetic head itself.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head suitable for use in a magnetic recording/reproducing device typified by R-DAT, and a method for manufacturing the same.

[Summary of the invention]

In the present invention, in the conductive film formed near the gap,
An induced current corresponding to the current flowing through the coil is caused to flow, so that the conductive film substantially forms an auxiliary gap, and the waveform equalization is performed by the magnetic head itself.

[Background technology]

A magnetic head used in a magnetic recording/reproducing device such as an R-DAT has differential characteristics. Therefore, when an ideal rectangular pulse (Fig. 11(a)) is recorded on a magnetic tape,
When an ideal magnetic head reproduces this, differential pulses corresponding to the rising and falling edges (FIG. 2(b)) are output. However, since various losses exist in an actual recording/reproducing system, high frequency components are removed, and the output waveform becomes distorted (Figure 11 (C)).
). Integrating such a pulse with a widened base results in the first
A waveform as shown in FIG. 1(d) is generated, and when this is compared with a predetermined reference level, a pulse as shown in FIG. 1(e) is obtained. As is clear from comparing FIG. 11(e) with FIG. 11(a), the original pulses recorded on the magnetic tape are not accurately reproduced.

Waveform equalization is necessary to prevent this.

Conventionally, in order to perform this waveform equalization, the amplitude of the high frequency component of the reproduced signal output from the magnetic head was increased using an amplitude circuit.
A phase shift circuit is used to compensate for the phase shift that occurs at this time.

[Problem that the invention seeks to solve]

As described above, since the conventional method only electrically equalizes the waveform of the output signal of the magnetic head, a correction error remains, and an attempt to reduce this error results in a complicated and expensive circuit.

Therefore, the present invention aims to reduce the burden on the electric circuit by allowing the magnetic head itself to perform waveform equalization without making the magnetic head complicated or large.

[Means for Solving the Problems-1] The magnetic head of the present invention includes a core through which a magnetic flux corresponding to the current flowing in the coil flows, a first conductive film formed near the gap between the core, and a conductive film formed in the vicinity of the gap and the first conductive film. a magnetic film formed between the first conductive film and the first conductive film, and a second conductive film formed to form a closed loop with the first conductive film so that at least a part of the magnetic flux passes through the closed loop. It is characterized by

[Operation-1] A coil is wound around the core, and when a current flows through the coil, magnetic flux corresponding to the current flows through the core. This magnetic flux is released into the gap via the magnetic film and flows into the magnetic film of the other core. Since a part of the magnetic flux passes through the closed loop, an induced current corresponding to this magnetic flux flows within the closed loop. Magnetic flux generated by this induced current travels between the magnetic film and the core. This magnetic flux flows out from one of the magnetic film and the core, jumps over the first conductive film, and flows into the other. The direction in which this magnetic flux flows is opposite to the direction of magnetic flux in the gap.

Therefore, waveform equalization can be efficiently performed by the magnetic head itself without making the magnetic head complicated or large.

[Means for solving the problem-2] The method for manufacturing a magnetic head of the present invention includes preparing a pair of cores, forming a first conductive film near the gap forming portion of each core, and A magnetic film is formed on the first conductive film, a pair of cores are bonded so that the magnetic films face each other with a gap, and a portion of the core is electrically connected to the first conductive film. A feature is that a second conductive film is formed around the periphery.

[Operation-2] A first conductive film is formed near the gap forming portion of the core. A magnetic film is formed on the first conductive film, and a spacer for forming a gap is further formed thereon as necessary. A pair of cores that have been subjected to the same treatment are joined with an adhesive or the like, if necessary, with their magnetic films (spacers) facing each other. A second conductive film is formed around the joined cores. The first conductive film and the second conductive film are electrically connected to form a closed loop.

The coil may be wound into a coil before or after joining.

Therefore, a magnetic head having a waveform equalization function can be manufactured through simple steps.

〔Example〕

3 and 4 show the manufacturing process of the magnetic head of the present invention. First, a pair of cores made of, for example, an oxide magnetic material are prepared. A groove 2 for winding a coil is formed in one core 1.

A conductive film 3 made of copper or the like is provided in the magnetic gap forming portion of the core 1.
is formed by vapor deposition, sputtering, plating, etc. (
Figure 3(a)). A magnetic film 4 is formed on the conductive film 3 by vapor deposition, sputtering, plating, or the like. The rear portion 5 of the magnetic film 4 is formed so as to be in direct contact with the core 1 (FIG. 3(b)). A spacer 6 made of a non-magnetic material such as glass is further formed on the magnetic film 4 to a thickness half the gap width by vapor deposition, sputtering, plating, etc. (FIG. 3(C)). ).

Similarly, a conductive film 13, a magnetic film 14, and a spacer 16 are formed on the other core 11 (FIG. 4). A groove may also be formed in the core 11, but if sufficient space can be secured by the groove 2 of the core 1, the groove can be omitted. bring into contact.

Next, spacer 6 (magnetic film 4) and spacer 16 (magnetic film 1)
4) The core 1 and the core 11 are joined so that they face each other and a gap 20 of a predetermined width is formed, and if necessary, the cores 1 and 11 are bonded with glass 21 (FIG. 4(a)). core 1 and core 1
1 is formed to have a predetermined length so that a plurality of magnetic heads can be manufactured from one block. Then, a groove 23 is formed on the upper surfaces of the joined cores 1 and 11, thereby forming a protrusion 22 having a predetermined width W (FIG. 4(b)). This width W is set to a value corresponding to the track width. A conductive film 24 made of, for example, copper is formed on the projections 22 and grooves 23 thus formed by vapor deposition, antibattering, plating, thermal spraying, etc. (FIG. 4(c)).

In this case, first, for example, a predetermined metal film is formed by vapor deposition, sputtering, etc., and electroplating is performed using this as an electrode, so that the film can be formed relatively quickly.

The block on which the conductive film 24 is formed is sliced at the center of the groove 23 (FIG. 4(d)). The surface on which the conductive film 24 of the head chip formed by slicing is formed is polished until a predetermined curvature and a predetermined gap depth are obtained (FIG. 4(e)). In this way, a magnetic tape contact surface is formed. A conductive film 24 formed around the outer periphery of the core 1.11 and a conductive film 3 formed near the gap 20.
13 are in direct contact for electrical continuity.

A coil is wound around the bed chip thus formed. If the cores 1 and 11 are sliced in advance to a predetermined width, they may be joined after the coils are wound.

FIG. 1 shows a perspective view of the head chip formed in this manner, with its center sliced.

Next, the flow of magnetic flux in the magnetic head of the present invention will be explained with reference to FIGS. 2 and 5. In Figure 2, 3
1 is the coil wound around core 1, 32 is the coil wound around core 11
The coil that is wound on.

For simplicity, the coil 31 is
．． Although 32 is wound in a single layer, it may be wound a predetermined number of times as necessary. The coils 31 and 32 are connected in series so that the magnetic fluxes generated when current flows therein are in the same direction (so that they are added). coils 31 and 32
can omit one of them.

When a current is passed through the coil 31 in a counterclockwise direction in the figure, a current r, (=rz) flows in the coil 32 in a clockwise direction in the figure.

At the center of the loop of the coil 31, a magnetic flux Φ
is generated, and a magnetic flux Φ is generated at the center of the loop of the coil 32 due to the current I2.

A part of the magnetic flux Φ□ is transferred from the core 1 to the magnetic WX4 via the rear part 5.
and is emitted from the magnetic film 4 into the gap 20.

The magnetic flux Φg released into the gap 20 flows into the magnetic film 14 and is transmitted to the core 11 from the rear part 15 thereof. core 1
The magnetic flux flowing into the core 1 is returned to the joined core 1 at the rear thereof.

In this way, the magnetic flux Φ1 circulates.

This also applies to the magnetic flux Φ2.

On the other hand, a part of the magnetic flux Φ1 flows out from the core 1 as a magnetic flux Φ3 and flows into the core 11 as a magnetic flux Φ. The magnetic flux Φ3 is a closed loop a, b, formed by the conductive film 24 and the conductive film 3.
Since the current flows through the closed loops a to d, an induced current flows in the direction of reducing the magnetic flux Φ□ (clockwise in the figure).

The magnetic film 4 also normally has conductivity, but the conductive film 3 has much higher conductivity, so most of the current I3 flows within the conductive film 3.

Similarly, an induced current I4 flows in closed loops a', b', C', and d' formed by the conductive film 24 and the conductive film 13.

The current I flows in the conductive film 3 in the width direction of the magnetic head (b-c direction). Therefore, as shown in FIG. 5, an induced magnetic flux is generated by the electric current generator 3, and this magnetic flux is transmitted to the core 1. Rear 5. It circulates through the loop of the magnetic film 4. That is, since the magnetic flux flowing out from the magnetic film 4 jumps over the conductive film 3 and flows into the core 1, the conductive film 3 constitutes a kind of gap g1. The direction of magnetic flux in this gap g is opposite to the direction of magnetic flux in gap go (20).

The above also applies to the current I4.

The two loops a to d and d' to d' are bb' and c
-c' are interconnected, but b and b' as well as C
Since the potentials at and C' are equal, between b-b' and c
No current flows between -c'.

Therefore, as shown in FIG. 6, the original gap 20 (g
, ), an auxiliary gap g□ spaced apart by a distance l, ■□, which allows the magnetic flux to flow out in the opposite direction to the gap 20.
, g2 will be substantially formed.

For simplicity, the magnetic path efficiency is 1 (the magnetic permeability of the core 1.11 is infinite), the resistivity of the conductive film 3.13.24 is O, and the current flowing through the coil is I (if the number of turns is N, it is 1 wire). (N times the current i flowing through the coil), then the gap g. The magnetic potential difference across the gap gi-gz is proportional to -I/2. Gap length (width) of each gap
is sufficiently smaller than the recording wavelength λ, and let the relative speed between the magnetic tape and the magnetic head be υ.

ω=2πυ/λ (1). When the magnetic tape is magnetized in the longitudinal direction, the magnetic flux ΦC passing through the head coil is ΦC=Φ, (Cog
(11t-(1/2) cos((L) (tel, /
v )) - (L/2)cos(ω(t-1□/υ))
] ...(2) becomes. ■ In the case of □=1□ (=1), equation (2) becomes as follows.

ΦC=ΦLICO5ωt(1-cos(lω/υ))
---(3) When formula (3) is expressed in a graph, the amplitude characteristics are as shown in FIG.

Assuming the frequency transfer function T(jω), T(jω)=1-cos(1(11/t
+) ・Fist Fist (4). (
Equation 4) indicates that the value of ω is between O and πυ/1, which is a high-frequency enhancement characteristic that attenuates the amplitude of low-frequency signals and enhances the amplitude of high-frequency signals. This indicates that no phase change occurs because there is no phase change.

If 1□≠1□, equation (2) has an imaginary term, so a phase change will occur.

When current flows through the coil 31 (32), magnetic flux flows through the core 1 (11), and this magnetic flux causes an induced current to flow through the closed loops a to d (a+ to d'), so the coils 31 (32),
It can be considered that the core 1 (11) and the closed loops a to d (a' to d') constitute a transformer as shown in FIG. The equivalent circuit of this transformer is the 9th
It will look like the figure. Here, R and L are the closed loop resistance and inductance, K is the coupling coefficient, ■ is the current flowing in the coil,
is the current flowing in the closed loop. From FIG. 9, the following equation holds true.

I'/I=jωL K/(jωL+R)...(5)(
5) Angular frequency ω from formula. It can be seen that the value I'/I becomes smaller at frequencies lower than (=R/L). In other words, this angular frequency ω. At higher frequencies, an induced current I' flows and the gap g, as described above. , gl, and g2 perform playback that emphasizes high-frequency components, and the angular frequency ω. At lower frequencies, the induced current flow does not flow sufficiently, and regeneration similar to the conventional case is performed only by the gap g0.

Taking all of the above into account, the relationship between the reproduction efficiency (relative sensitivity) S of the magnetic head and the angular frequency ω is shown in FIG. As the values R and K change, the characteristics also change. Therefore, by appropriately selecting the gap length of the gap g0, the film thickness of the magnetic film 4.14, the material and film thickness of the conductive film 3.13, etc., Nyquist's first criterion etc. can be satisfied (approximately satisfied). Predetermined characteristics can be set.

〔effect〕

As described above, according to the present invention, since the auxiliary gap is formed by the conductive film formed near the gap, efficient waveform equalization by the magnetic head itself is possible without complicating the structure. Become. Therefore, the burden on the electrical waveform equalization circuit is reduced and its configuration is simplified. Furthermore, the manufacturing process is simple, and inexpensive magnetic heads can be mass-produced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the magnetic head of the present invention with its center sliced, FIG. 2 is a perspective view illustrating the flow of magnetic flux, and FIGS. 3 and 4 are perspective views illustrating the manufacturing process. Figure 5 is a sectional view explaining the flow of magnetic flux, Figure 6 is an illustration of the gap, Figure 7 is a characteristic diagram of the magnetic flux,
Figure 8 is a circuit diagram explaining the induced current, and Figure 9 is a circuit diagram explaining the induced current.
10 is a characteristic diagram of its reproduction efficiency, and FIG. 11 is a waveform diagram illustrating the characteristics of a conventional magnetic head. 1... Core 2... Groove 3... Conductive film 4... Magnetic film 5... Rear part 6... Spacer 11... Core 13... Conductive film 14... Magnetic film 15 ... Rear part 16 ... Spacer 2o ... Gap 21 ... Glass 22 ... Protrusion 23 ... Groove 24 ... Conductive film 31, 32 ... Coil patent applicant Pioneer Corporation

Claims (2)

[Claims] (1) A core through which a magnetic flux corresponding to the current flowing in the coil flows, a first conductive film formed near a gap between the core, and a magnetic field formed between the gap and the first conductive film. 1. A magnetic head comprising: a second conductive film; and a second conductive film formed to form a closed loop with the first conductive film so that at least a part of the magnetic flux passes through the closed loop. (2) Prepare a pair of cores, form a first conductive film near the gap forming part of each core, form a magnetic film on the first conductive film, and form the magnetic film in the gap A pair of the cores are joined so as to face each other via the core, and a second conductive film is formed around the core so that a part of the core is electrically connected to the first conductive film. A method of manufacturing a magnetic head.