JPS63113906A - Step-up type magnetic head - Google Patents

Abstract

PURPOSE:To obtain a step-up type magnetic head with high transmission efficiency by forming a head signal winding part including a transformer primary circuit and a head magnetic circuit part by the thin film technology and applying transformer secondary winding as balanced winding so as to obtain a high step ratio to the decided inductance. CONSTITUTION:A nonmagnetic block 16a made of glass placed at the tip and a ferromagnetic substance 11 such as an Mn-Zn ferrite forming the lower base 9 are incorporated by glass bonding, and a 1-turn coil 12 made of Cu or Al underlying a head lower magnetic substance 10 from the surface of the block 16a to the surface of the ferromagnetic substance 11 is formed by vacuum vapor deposition or the like to cover it by a head upper magnetic substance 13. Moreover, a nonmagnetic insulation layer 15 is provided on the magnetic substance 13 and an intermediate magnetic layer 14 is provided to the other part, the surface is made flat and the ferromagnetic block 17 provided with a nonmagnetic block 16b and a secondary winding slot 18 and the upper base 20 are bonded by glass on the layer 14.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a wire-wound magnetic head integrally incorporating a step-up transformer, and particularly to a video head-shaped magnetic head.

BACKGROUND OF THE INVENTION Conventionally, this type of magnetic head is as shown in FIG.
A head configuration in which a step-up transformer is coupled to a one-turn (or several turns at most) wire-wound head is known. This type of configuration aims to increase the output per turn by minimizing the number of signal windings and downsizing the magnetic circuit linked to them.) The low absolute output due to the low number of windings is This is to be compensated for by an up transformer. FIG. 9 shows a conventional example suitable for two types of video heads (Japanese Patent Publication No. 53-16687).

In the same figure, 1 and 2 are magnetic helad cores that are brought together to form a head gas op 3, and 4 is a half of a transformer core, which is brought together at the rear of the said herad core 1 to form a transformer core with a substantially ring magnetic path. are doing. 6 is a metal layer embedded in a groove that divides the helad core into a front gap portion and a back gap portion. A one-turn coil 6 passes through the inner groove 7 of the transformer core 4, and its end is connected to the end of the metal layer 5 to form a one-turn closed coil interlinking with the head magnetic circuit and the transformer magnetic circuit. There is. 8 is a secondary coil of the transformer. In this way, the head configuration is equivalent to that shown in FIG. 7.

This problem arises because the head core and the vicinity of the 1-turn winding have a so-called bulk configuration, so the head magnetic circuit and the 1-turn winding are sufficiently small to reduce the 1-turn inductance and DC resistance of the head. In addition, the primary coil of the transformer, 2
The problem is that the coupling coefficient of the transformer cannot be obtained sufficiently high because the secondary coil arrangement is inappropriate. I will explain why these become a problem when considering a highly efficient head.

Now, consider the circuit shown in FIG. 10 as a simple equivalent circuit of the head shown in FIG. However, the DC resistance and stray capacitance of the secondary coil are omitted. Here, Ll and L2 are the self-inductances of the primary and secondary coils of the transformer, respectively, M is the mutual inductance between the primary and secondary coils, and LH
is the one-turn head inductance, r is the one-turn DC resistance including both the head winding and the transformer primary coil,
Ei is a regenerative electromotive force induced in the head winding, and Eo is a secondary output of the transformer.

Now, the quantities that are important in practical use for such a head are the inductance L of the entire head including the transformer, the real part of the impedance Re (Z), and the transmission efficiency G = Eo/E
It is i.

L determines the high frequency usage limit of the head, and L at a sufficiently high frequency is L = LH - N2 + 12 (2 at t-) from Figure 10.
・・・・・・・・・・・・(1) is calculated. Here, N is the number of transformer secondary windings (ie, step-up ratio), and K is the coupling coefficient of the transformer. M in the first equation
The first term (L) is an inductance that inevitably occurs regardless of the performance of the transformer, but the second term is an amount added when the transformer is not ideal.

Since N needs to be as large as possible for the L value that is conveniently permissible, LH should be sufficiently small, and the degree of coupling of the transformer should be increased to make K sufficiently close to "1" so that the first equation It is necessary to make the second term as small as possible.

Next, Re(Z) determines impedance noise, and the lower the better. At frequencies higher than the low cutoff frequency, Re(Z) is calculated as LH x Ll
If this is the case, the second equation is approximately equal to 1, and the one-turn resistance r on the primary side is observed to be approximately the square of the step-up ratio from the secondary side. Therefore, r needs to be sufficiently low.

Furthermore, the transmission efficiency G becomes at frequencies above the low cutoff, and if LH and Ll are also set, GΣ becomes -N...
(5), and the transmission efficiency decreases by the step-up ratio N to K. Therefore, K needs to be sufficiently close to "1".

Problems to be Solved by the Invention In order for the head characteristics to have high performance when including the step-up transformer, it is necessary that the inductance and DC resistance of one turn of the head be sufficiently small, and that the coupling of the transformer be sufficiently small. It is necessary that the coefficient be sufficiently close to .degree. 1", and in the conventional example, these points are not sufficiently satisfied.

SUMMARY OF THE INVENTION An object of the present invention is to provide a step-up magnetic head that can have a high step-up ratio for a predetermined inductance, has low resistance, little impedance noise, and has high transmission efficiency.

Means for Solving the Problems The step-up magnetic head of the present invention includes a thin film head magnetic circuit formed on a lower substrate, and an upper substrate that includes at least a part of a ferromagnetic thin film formed in the lower substrate. A transformer magnetic circuit constructed with

a closed thin film coil formed on the lower substrate so as to interlink with both the head magnetic circuit and the transformer magnetic circuit, and a transformer secondary winding interlink with the transformer magnetic circuit; The secondary winding is divided into a part that goes around the upper substrate and a part that goes around the lower board, and is wound in a balanced manner using bulk winding, and further, the lower board has the ferromagnetic thin film inlaid with a non-magnetic material. at least a portion of the ferromagnetic thin film, and the film surface of the ferromagnetic thin film is substantially orthogonal to both the substrate surface of the lower substrate and the recording medium facing surface of the magnetic head. Features.

Function: With this configuration, the head magnetic circuit section and the head signal winding section are formed using thin film technology and can be miniaturized to the necessary minimum size, making it possible to minimize the head inductance and the DC resistance of the signal winding. Furthermore, by forming the transformer secondary winding into a balanced winding configuration, it is possible to increase the coupling coefficient K, which provides tighter coupling between the primary and secondary windings. In this way, as the head characteristics including the transformer part,
In terms of inductance, N can be made larger than the allowable value of fcL determined for practical use, and in terms of Re■, it can be made much smaller, and in terms of transmission efficiency, it is closer to the step-up ratio itself. I can do it.

Furthermore, since the transformer magnetic circuit in the lower substrate is provided by a ferromagnetic thin film having a film surface perpendicular to the surface of the lower substrate, it is easy to make the magnetic path thickness smaller than the inner diameter of the coil. Therefore, it is easy to reduce the number of magnetic circuits that are not linked to the transformer primary winding, and the coupling between the primary and secondary windings can be made tighter. In addition, with such a configuration, it is easy to form a multilayer structure using eight ferromagnetic thin films, so that a transformer magnetic circuit with excellent high frequency characteristics can be constructed.

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 7.

1 and 2 show the entire magnetic head of the present invention, with FIG. 1 being a plan view and FIG. 2 being a sectional view taken along line FiA-A'.

However, in FIG. 1, the upper part of the line BB' in FIG. 2 and the secondary coil of the transformer are omitted for drawing purposes.

In Figures 1 and 2, 9 (part below C-C')
The lower substrate of the magnetic head is a ferromagnetic thin film 11 sandwiched between non-magnetic materials 16c and further bonded with non-magnetic materials 16ai. When attempting to mass produce a large number of heads connected in the direction DD' in FIG. 1, the shape of the lower substrate will be as shown in FIG. 3. Glass bonding is suitable for these connections. The ferromagnetic thin film 11 constitutes a lower magnetic body of the transformer. Note that this magnetic film 11
The membrane plane is perpendicular to the plane of the paper in FIG. 1, and parallel to the plane of the paper in FIG.

A head lower magnetic body 1o is formed on the lower substrate, and a closed one-turn coil 12 is formed by connecting the magnetic film 10 and the magnetic film 10, 11 as shown in the figure. The vicinity of the part of the coil 12 where the head magnetic circuit K is connected is the one-turn signal winding ak of the head.
The area near the magnetic circuit K of the transformer constitutes a primary one-turn winding of the transformer. Next, a non-magnetic gap layer (not shown) of a predetermined thickness is formed on the head lower magnetic body 10 at a portion where the Herad gap is formed.
The upper magnetic body 13 of the head magnetic circuit is formed of a ferromagnetic thin film. On the other hand, the intermediate magnetic layer 14 is formed of a ferromagnetic thin film on the ferromagnetic thin film 11 of the transformer. A nonmagnetic insulating layer 15 is formed to fill the recesses created by forming each of the above thin film patterns, and the upper surface is polished to form the intermediate magnetic layer 15.
Processing is performed so that a plane indicated by B-B' with 4 appearing on the surface is obtained.

In each of the above thin film processes, the ferromagnetic film part is a vacuum deposited film or sputtered film of permalloy or amorphous magnetic alloy, the coil layer is a vacuum deposited film or sputtered film of Cu or AI, and the insulating layer film is a vacuum deposited film or sputtered film of Cu or AI. S
102 and A12o3 are suitable.

Next, the part above B-B/ in FIG.
Also, the planes B-B' are polished so that they are the same plane. Glass, forsterite, barium titanate, etc. are suitable for the non-magnetic part, Mn--Zn ferrite, etc. are suitable for the ferromagnetic block part, and glass bonding is suitable for joining the two.

The head upper substrate prepared in this way and the head lower substrate on which the thin film process has been completed are joined at the position shown in FIG. Glass bonding is preferred for bonding, but if there is an adverse effect on the magnetic thin film, bonding with an organic adhesive or the like may be used.

After the head formed in this manner is subjected to predetermined external processing, etc., bulk winding is performed to form the secondary coil 19 of the transformer. This secondary coil 19 is divided into an upper magnetic circuit and a lower magnetic circuit of the transformer, and wires are connected so as to form a balanced winding. The recording medium contacting surface of the magnetic head is a surface indicated by 20, and the substrate surfaces of the father upper substrate and lower substrate are planes indicated by BB' and CC', respectively.

As is clear from the above description of the embodiment, the one-turn head portion consists of a head upper magnetic body 13, a lower magnetic body 10, and a
The transformer section is composed of a turn coil 12, and the transformer part includes a transformer magnetic circuit consisting of a bulk ferromagnetic block 17, an intermediate magnetic layer 14, and a transformer lower magnetic body 11, and a one-turn coil 12 and a multi-turn secondary coil 19 interlinked with the transformer magnetic circuit. Consisted of.

The head magnetic circuit and single-turn winding can be formed to the minimum required size using thin film technology, so
Turn inductance and DC resistance of one turn can all be kept to a minimum. In addition, since the transformer secondary winding is formed as a balanced winding at a position close to the primary winding, it is possible to achieve higher coupling between both transformer windings than in the conventional example. When all of the magnetic flux that interlinks with the winding also interlinks with the secondary winding, the coupling coefficient is 1''
).

Furthermore, since the lower magnetic material of the transformer is arranged as a thin film so as to be perpendicular to the lower substrate surface and the surface in contact with the medium, the magnetic path D-
It is easy to make the thickness of the D' force direction (FIG. 1) smaller than the inner dimension of the thin film coil.

For this reason, even if the bulk ferromagnetic baroque 17 is a continuous integral piece in the direction perpendicular to the plane of the paper of FIG. 2, the total number of transformer magnetic circuits that do not interlink with the coil 12 can be reduced.

For explanatory purposes, Figures 1 and 2 show the one-turn head part in a larger scale than the other parts, but in reality, for example, when applied to a video head for a rotary cylinder, the external appearance of the head is drawn in a practical dimensional ratio. The result will be something like the one shown in Figure 4. It can be seen that the external appearance is very similar to a so-called video head type, and that it can be easily introduced into a rotary head type recording/reproducing apparatus.

FIG. 5 shows another embodiment of the present invention, and since it specifically relates to the lower substrate, only that part is shown. In this example, the ferromagnetic thin film 11a in the lower substrate is formed as a laminate of a ferromagnetic thin film and an insulating layer, thereby providing a transformer magnetic circuit with low eddy current loss. When adopting such a configuration, in order to further reduce eddy current loss, the transformer magnetic circuit in the upper substrate is also provided with a laminated structure similar to that of the lower substrate, and the configuration shown in Fig. 6 is adopted. is preferred.

In each of the above embodiments, the /'i1 turn head portion is constructed as a so-called ring-shaped head, but a one-turn perpendicular recording head shown in FIG. 7 may also be used here. In the figure, 23 is a main magnetic pole for recording and reproducing, 24 is an auxiliary magnetic pole, and 12 is a one-turn coil.

In such a perpendicular recording head, the magnetic path is more open than that of the talling type head shown in FIGS. 1 and 2, so the magnetic circuit... The efficiency improvement is particularly remarkable when it is made smaller, and the effect of making it into one turn and combining it with a step-up transformer is great.

Further, in the above embodiment, the head portion has one turn, but it can also be configured to have several turns, and in this case as well, the features of the present invention described above can be exhibited.

For actual coil production, a well-known thin film coil formation technique can be used.

As described in the detailed description of the invention, in the step-up magnetic head of the present invention, the head magnetic circuit portion and the head signal winding portion including the entire transformer primary circuit are formed using thin film technology, and the transformer secondary winding is balanced winding. Therefore, it is possible to obtain a step-up type magnetic head with a high level of inductance for a predetermined inductance, and a step-up type magnetic head with low resistance, little impedance noise, and high transmission efficiency. Further, according to the present invention, a particularly suitable configuration can be adopted as a rotating head type video head.

Furthermore, in the present invention, since the transformer magnetic circuit is provided by a ferromagnetic thin film that is substantially orthogonal to the thin film configuration plane, it is possible to reduce the magnetic path that does not interlink with the primary coil, and it is possible to increase the coupling coefficient of the transformer. . Furthermore, with this configuration, it is easy to form the transformer magnetic circuit into a laminated structure, and a step-up head with low eddy current loss can be obtained.

[Brief explanation of the drawing]

1 and 2 are a plan view-2 sectional view showing one embodiment of the present invention, FIG. 3 is a perspective view showing the lower substrate, and FIG.
The figures are a plan view showing the external appearance of the head of the present invention, FIG. 5 is a partial perspective view showing a lower substrate in another embodiment of the present invention, and FIG.
The figure is a partial perspective view showing a state in which the upper and lower substrates are joined, FIG. 7 is a partial cross-sectional view showing another embodiment of the present invention, and FIG. 8 is a principle diagram of a step-up type magnetic head. ,
9 is a sectional view showing a conventional example, and FIG. 10 is an equivalent circuit diagram of a step-up type magnetic head. 9...Head lower substrate, 10...Head lower magnetic body, 11.11a...Transformer lower magnetic body, 12...1 turn coil, 13.・・・
...Head upper magnetic body, 14...Transformer intermediate magnetic layer, 16...Nonmagnetic insulating layer, 16a, 1
6b, 16c...Nonmagnetic block, 17, 17
a...Tran 2. Upper magnetic body, 18...
- Winding groove for transformer secondary winding, 19...Transformer secondary winding. Name of agent: Patent attorney Toshio Nakao and 1 other person9-
11th end of the month 1st 1st 12I/9---Trans 2nd Pengya Ai: rS2 Figure 3 Figure 4 Figure 10, /2. /, 3 Figure 5 E) Figure 6 // Sawa Figure 7 Figure 8 Figure 9

Claims (6)

[Claims] (1) A thin film head magnetic circuit formed on a lower substrate, a transformer magnetic circuit configured together with the upper substrate and including at least a part of the first ferromagnetic thin film formed in the lower substrate, and the head magnetic circuit and a closed thin film coil formed on the lower substrate so as to interlink with both of the transformer magnetic circuits, and a transformer secondary winding interlinked with the transformer magnetic circuit, and this secondary winding is formed on the upper substrate. The step-up magnetic head is divided into a part that revolves around a lower substrate and a part that goes around a lower substrate and is balanced-wound using bulk winding, the lower substrate sandwiching the first ferromagnetic thin film between non-magnetic materials. has at least a part of the structure,
The step-up magnetic head is characterized in that the film surface of the first ferromagnetic thin film is substantially perpendicular to both the substrate surface of the lower substrate and the recording medium facing surface of the magnetic head. (2) The step-up magnetic head according to claim 1, wherein the thin film coil is configured to interlink with both the head magnetic circuit and the transformer magnetic circuit in one turn. (3) A step-up magnetic head according to claim 1, wherein at least one of the upper substrate and the lower substrate is configured to include a bulk ferromagnetic portion forming a part of a transformer magnetic circuit. . (4) A step-up magnetic head according to claim 1, wherein the first ferromagnetic thin film is a plurality of layers laminated with an insulating layer interposed therebetween. (5) The upper substrate has a second ferromagnetic thin film constituting a part of the transformer magnetic circuit, and the film surface of the second ferromagnetic thin film is the substrate surface of the upper substrate and the recording head of the magnetic head. 2. The step-up magnetic head according to claim 1, wherein the magnetic head is substantially perpendicular to both surfaces in contact with the medium. (6) A step-up magnetic head according to claim 5, wherein the second ferromagnetic thin film is laminated in multiple layers with an insulating layer interposed therebetween.