JPH11307383A - Manufacture of rotary transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture method of a rotary transformer, with which a distance between coils is reduced, a connection degree between transformers can be improved and superior transmission efficiency can be obtained. SOLUTION: A core 1 where a plurality of circular grooves 1a and 1b are formed on a surface is formed of a magnetic material. The core 1 is installed in a state, where the surface faces upward and adhesive 4, and coils 3A and 3B are installed in the circular grooves 1a and 1b. A surface plate 6 is loaded on the surface of the core 1 via a separation film before adhesive 4 is cured. The top/bottom of the core 1 are inverted in a state, where the surface plate 6 is closely adhered and is put in a high temperature chamber in this state. Then, adhesive 4 is cured, the core 1 is taken out from a thermostatic chamber after adhesive 4 has been cured and the separation film and the surface plate 6 are taken out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a rotary transformer used in a magnetic recording / reproducing apparatus such as a video tape recorder (VTR) and a data streamer (DS), and in particular, a high degree of coupling between the transformers. The present invention relates to a method for manufacturing a rotary transformer capable of obtaining transmission efficiency.

[0002]

2. Description of the Related Art A rotary transformer is used for transmitting a signal from a recording / reproducing amplifier to a rotary magnetic head used in a VTR, a DS or the like by an electromagnetic induction action. In this rotary transformer, as shown in FIG. 7, a core 1 having a plurality of (two) annular grooves 1a and 1b formed concentrically on one surface, and arranged in the annular grooves 1a and 1b of the core 1. And coils 3A and 3B. And in such a rotary transformer, the core 1 is formed of a magnetic material,
After the adhesive 4 is filled in the annular grooves 1a and 1b of the formed core 1, the coils 3A and 3B are mounted and the adhesive 4 is cured.

[0003] In recent years, technological innovations to reduce the size, weight, and quality of VTRs and DSs have been remarkable.
Higher recording density and shorter recording wavelength have been developed. For example, with respect to magnetic heads, the number of magnetic heads is increased, optimization is performed by specializing the functions of individual magnetic heads, and C / N (carriage) of the total signal input / output is performed.
er to noise ratio). For this reason, a rotary transformer used for a magnetic head for transmitting a signal is required to have high transmission efficiency and to improve crosstalk characteristics between channels.

On the other hand, in order to improve the transmission efficiency of the rotary transformer, it is necessary to increase the degree of coupling between the transformers. As a method of increasing the degree of coupling, it is necessary to improve the positional accuracy of the surface of the magnetic material and to use a rectangular wire for the coil. Increasing the coil width by using it to increase the opposing area, and making the coil groove shallow to reduce the distance between opposing transformers, etc. It is known that it can greatly contribute.

[0005]

However, in the above-described rotary transformer shown in FIG. 7, the coil is easily lifted from the adhesive melted at the time of manufacturing, and the coil or the adhesive is hardened in the core 1 in a state where the adhesive is cured. May protrude from the surface. When the above-described method of reducing the distance between the transformers is employed for the purpose of improving the coupling between the transformers, if the coils or the adhesive protrude, the coils may come into contact with each other or between the coils and the core during use (interference). However, there is a problem that rotation unevenness and noise are generated. In particular, a rotary transformer has a narrow distance between opposing transformers of 25 μm to 50 μm, and even a slight protrusion may cause a hit, and therefore a solution to the problem has been strongly demanded.

On the other hand, as a countermeasure against the above problem, conventionally, the depth of the coil groove is set to about twice the diameter of the wire used for the coil, but the lifting of the coil is completely prevented. It was difficult. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a method of manufacturing a rotary transformer capable of reliably preventing a coil from being lifted, having a small distance between transformers, having a high degree of coupling between transformers, and obtaining excellent transmission efficiency. The purpose is to do.

[0007]

To achieve the above object, a method for manufacturing a rotary transformer according to the present invention comprises:
An annular groove is formed on the surface of the annular core, the core is held in a state where the annular groove is opened upward, an adhesive is filled in the annular groove, and a coil is loaded. Place the platen on the surface, then turn the platen and the core upside down before the adhesive cures, position the core on the platen, and place the core on the platen The adhesive was cured in a state where was positioned.

In the method of manufacturing a rotary transformer according to the present invention, after an adhesive and a coil are loaded in an annular groove of a core, a platen is placed on the annular groove opening surface of the core to close the annular groove opening. In this state, the core is turned upside down to cure the adhesive. For this reason, the coil can be positioned at the top of the annular groove and bonded, and the adhesive or the coil is prevented from protruding by the platen, so that the adhesive or the coil does not protrude from the annular groove, and the distance between the coils is reduced. And the degree of bonding can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 illustrate a method of manufacturing a rotary transformer according to an embodiment of the present invention. FIG. 1 is an exploded perspective view of the rotary transformer, FIG. 2 is a partial cross-sectional view of the rotary transformer, and FIG. FIGS. 4 and 5 are partially enlarged views of FIG. 2, and are cross-sectional views showing an outline of a manufacturing process of the rotary transformer.

First, a rotary transformer will be described with reference to FIGS. 1, 2 and 3. Reference numeral 1 denotes a core made of a magnetic material, and two annular grooves 1a and 1b are formed concentrically on the surface of the core 1. Is formed. This core 1 has an annular groove 1a,
The coils 3A and 3B are attached to 1b by bonding with an adhesive 4. As shown in detail in FIG. 3, the rotary transformer includes annular grooves 1a, 1b of coils 3A, 3B.
The positions near the opening surface and the positions near the opening surfaces of the annular grooves 1a and 1b of the adhesive 4 are located on the same plane as the opening surfaces of the annular grooves 1a and 1b, and the coils 3A and 3B and the adhesive 4 It does not protrude (protrude) from the opening surfaces 1a and 1b (described later), and the distance between the coils can be reduced.

This rotary transformer is manufactured as described below. That is, first, the core 1 having the annular grooves 1a and 1b is formed from a magnetic material, and the core 1 is placed with the opening surfaces of the annular grooves 1a and 1b positioned upward, and bonded in the annular grooves 1a and 1b. Agent 4 and the coils 3A, 3B are placed on the adhesive 4 in the annular grooves 1a, 1b.
Is loaded. As the adhesive 4, a well-known adhesive can be used, but desirably, an expandable adhesive, an adhesive containing magnetic powder, an expandable adhesive containing magnetic powder, a thermosetting adhesive, or An adhesive sheet containing any of these adhesives on a substrate is used.

Subsequently, as shown in FIG. 4, a release film 5 is put on the surface of the core 1 in close contact with the core 1, and a surface plate 6 is placed on the release film 5. The release film 5
Use of a thermoplastic resin film such as a polyester film, desirably a film that has been subjected to a release treatment with silicon or a fluorine compound, and a platen 6 in which the flatness of the surface on the release film 5 side is defined, Preferably, a material made of ceramic is used.

Next, as shown in FIG. 5, the core 1 is turned upside down with the release film 5 and the platen 6 in close contact with each other, and the weight plate 7 is placed on the core 1 (on the back surface of the core 1). The adhesive 4 is placed on a thermostat bath and cured. When the adhesive 4 has hardened, the core 1 is taken out of the thermostat and the weight plate 7 is removed to obtain the rotary transformer shown in FIGS.

In the rotary transformer manufactured as described above, when the adhesive 4 is cured, the core 1 has the annular grooves 1a, 1a.
b is opened downward, and the openings of the annular grooves 1a and 1b are closed by the release film 5 and the platen 6, so that the adhesive 4 and the coils 3A and 3B do not protrude from the annular grooves 1a and 1b. The coils 3A and 3B are fixed to the upper portions of the annular grooves 1a and 1b (see FIG. 3). Therefore, the distance between the coils is reduced, and the distance between the coils can be further reduced, so that excellent transmission efficiency can be obtained.

[0015]

Next, an embodiment will be described. 1. Example 1 Foaming adhesive 4 is poured into annular grooves 1a and 1b of core 1, and coils 3A and 3B are placed on foaming adhesive 4,
A ceramic platen 6 is placed with the release film 5 interposed between the surfaces of the core 1 (see FIG. 4). Thereafter, the core 1 is turned over while being in close contact with the surface plate 6 and the like, the weight plate 7 is placed on the core 1, and the adhesive 4 is foamed and cured using a thermostat or the like. Then, after the adhesive 4 is cured, the core 1 is taken out of the thermostat and the weight plate 7 is removed.

2. Example 2 An ordinary thermosetting liquid adhesive was used as the adhesive 4 in Example 1 above. Others are the same as the first embodiment. 3. Example 3 The magnetic powder was added to the adhesive 4 in Example 1 in a weight ratio of 20%.
The mixture was used to a certain extent. Others are the same as the first embodiment.

When the coupling coefficients of Examples 1, 2, 3 and the comparative example (see FIG. 7) manufactured by the conventional manufacturing method were compared, the result shown in FIG. 6 was obtained. It was demonstrated that the examples were excellent, and specifically, that the examples obtained a coupling coefficient higher than that of the comparative example by 0.01 or more. However, the characteristic values in FIG. 6 are coupling characteristics between transformers obtained by fixing the distance between the transformers to 38 μm and short-circuiting the channel adjacent to the evaluation channel.

In the above-described embodiment, the other case where a transformer is formed is not particularly described, but the present invention can be applied to only one side of a set of transformers, and a considerable effect can be obtained. can get.

[0019]

As described above, according to the method for manufacturing a rotary transformer according to the present invention, the coil is housed together with the adhesive in the annular groove of the core, and the platen is placed on the opening surface of the annular groove. With the platen in close contact with the platen, it is turned upside down and the adhesive is cured in this state, so that the coil and the adhesive do not protrude from the annular groove, the distance between the coils can be reduced, and the coupling can be improved. Excellent transmission efficiency is obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view schematically showing a rotary transformer manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a sectional view schematically showing a part of the rotary transformer.

FIG. 3 is an enlarged view of a portion A in FIG. 2;

FIG. 4 is a schematic sectional view showing an outline of one step of the manufacturing method.

FIG. 5 is a schematic cross-sectional view showing an outline of a step that follows the step of FIG.

FIG. 6 is a graph showing a coupling coefficient of the rotary transformer according to the embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view showing an outline of one process of a conventional method for manufacturing a rotary transformer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Core, 1a, 1b ... Annular groove, 3A, 3B ... Coil, 4 ... Adhesive, 5 ... Release film, 6 ... Surface plate, 7 ... Weight plate.

Claims (6)

[Claims] An annular groove is formed on the surface of an annular core, the core is held in a state where the annular groove is opened upward, an adhesive is filled in the annular groove, and a coil is loaded. Next, a platen is placed on the surface of the core, and then, before the adhesive is cured, the platen and the core are turned upside down to position the core on the platen. A method for manufacturing a rotary transformer, wherein the adhesive is cured while the core is positioned on a board. 2. The rotary according to claim 1, wherein a weight plate is placed on the core while the core is positioned on the surface plate, and the adhesive is cured while a load is applied by the weight plate. Transformer manufacturing method. 3. The adhesive according to claim 1, wherein the adhesive is a foamable adhesive, a magnetic powder-containing adhesive, a magnetic powder-containing foamable adhesive, a thermosetting adhesive, or any one of these adhesives as a base material. The method for producing a rotary transformer according to claim 1, comprising an adhesive sheet contained in (1). 4. The rotary according to claim 1, wherein after the coil is loaded in the annular groove of the core, a release film is put on the surface of the core, and the platen is placed on the release film. Transformer manufacturing method. 5. The method of manufacturing a rotary transformer according to claim 1, wherein a plurality of annular grooves are formed concentrically on said core, and separate coils are respectively loaded in said annular grooves. 6. The platen according to claim 1, wherein said platen is made of ceramic.
A method for producing the rotary transformer according to the above.