JPH0774038A - Manufacture of rotary transformer - Google Patents

Abstract

PURPOSE:To obtain a manufacturing method, of a rotary transformer, which can automate a manufacturing process, which can reduce manufacturing costs and which can accommodate the smaller size and the higher density of coils due to the smaller size of the rotary transformer. CONSTITUTION:Ring-shaped recessed grooves 3A to 3E are formed on one face of a disc-shaped ferrite core 1, ring-shaped conductor metal foils are bonded to the ring-shaped recessed grooves 3A to 3E, and spiral coils 6A to 6E are formed of the ring-shaped conductor foils by an etching operation. Thereby, the higher density of the spiral coils is realized, and their manufacturing process can be automated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a rotary transformer, particularly in a magnetic recording / reproducing apparatus, in which a recording signal is supplied to the rotary magnetic head from the outside or the recording signal is derived from the outside. The present invention relates to a method for producing a rotary transformer suitable for use in.

[0002]

2. Description of the Related Art Conventionally, the following types of rotary transformers are known.

In the rotary transformer assembly proposed by the present applicant in Japanese Utility Model Publication No. 62-18013, a concentric circular groove is formed on one surface of a disk-shaped ferrite core constituting a rotor core or a stator core, and a wire rod is formed in the circular groove. A configuration in which a winding formed by winding is provided is disclosed.

Further, Japanese Patent Laid-Open No. 2-30 proposed by the present applicant
No. 8505, a core for a rotary transformer in which a sheet-shaped coil body formed by punching out a polymer sheet of a resin or the like having a conductor pattern in the same shape as the annular groove is fixed to the annular groove of a similar disk-shaped ferrite core. A device and method of making the same are disclosed.

Further, in JP-A-59-127812, a circular groove having a desired coil pattern is formed in advance in a disk-shaped ferrite core, the groove is filled with a conductor paste, and then the disk-shaped ferrite core. There is disclosed a method for manufacturing a rotary transformer, in which a coil is formed by firing and baking the conductor paste.

Further, in Japanese Patent Laid-Open No. 4-42908, a spiral groove having a desired coil pattern is previously formed in a disk-shaped ferrite core, and the groove is filled with molten metal or metal powder. A method of manufacturing a rotary transformer is disclosed in which a coil is formed by cooling after melting (sintering).

[0007]

By the way, the manufacturing method of the rotary transformer shown in each of the conventional examples has the following problems.

First, in the manufacturing method in which the coil is formed by using the wire material and arranged in the groove, it takes time and effort to form the coil,
The number of man-hours required for manual work increases, and automation is difficult.

Further, when a sheet-shaped coil body formed by forming a conductor pattern on a polymer sheet such as resin is used, there is a drawback that the manufacturing cost becomes high. There is a limit to the miniaturization.

Further, in the case where a groove of a coil pattern is formed in advance in a ferrite core and the groove is filled with a conductive paste or a molten metal to form a coil, it is practical to process the groove corresponding to the coil pattern. It is difficult, and at present it is considered difficult to commercialize.

In view of the above points, the present invention can realize the automation of the manufacturing process and the reduction of the manufacturing cost, and can cope with the miniaturization or high density of the coil (conductor pattern) accompanying the miniaturization of the rotary transformer. It is intended to provide a method for manufacturing a rotary transformer.

[0012]

In order to achieve the above object, a method of manufacturing a rotary transformer according to the present invention is such that at least one annular groove is provided on one surface of a disk-shaped magnetic core, and the annular groove is formed. A ring-shaped conductor metal foil is adhered to and the conductor pattern is formed by the ring-shaped conductor metal foil by etching.

Further, it is also possible to form a plating layer on the conductor pattern.

[0014]

In the method of manufacturing the rotary transformer of the present invention, the circular conductor metal foil bonded to the circular groove of the disk-shaped magnetic core is etched to form a spiral shape or the like which becomes a coil in the circular groove. Since the conductor pattern is formed and the process can be automated, it is suitable for mass production and the manufacturing cost can be reduced. Further, the number of turns and the line width of the conductor pattern to be the coil can be freely set by etching, and the coil can be downsized or the density can be increased. Therefore, as compared with the conventional method of arranging the coil or sheet-shaped coil body made of a wire rod in the annular groove or the method of forming the coil by filling the groove of the coil pattern with the conductive paste or the molten metal, It is easy to manufacture and low cost, and it is also suitable for downsizing and thinning of rotary transformers.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a rotary transformer according to the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of the present invention. 1 and 2, reference numeral 1 denotes a disc-shaped ferrite core that serves as a rotor core or a stator core of a rotary transformer, a through hole 2 is formed in the center thereof, and a plurality of concentric circular annular recesses are formed on one surface. Grooves 3A to 3E are formed. The groove width of each of the annular concave grooves 3A to 3E is set to an arbitrary width according to a desired coil pattern according to the application. A high resistance ferrite is used as the ferrite core.

Next, annular copper foils 5A to 5E, which are annular conductor metal foils corresponding to the respective sizes of the annular concave grooves 3A to 3E of the disk-shaped ferrite core 1, are prepared. The circular copper foils 5A to 5E are formed into a circular ring shape (formed in the same shape as the circular groove) by etching the copper foil in accordance with the size of each of the circular groove 3A to 3E. It is a thing. Then, as shown in FIG. 3, the annular copper foils 5A to 5E are fitted into the bottom surfaces of the annular recessed grooves 3A to 3E corresponding thereto, respectively, and fixed by adhesion. The bottom surface of the annular groove 3A to 3E or the annular copper foil 5A
Adhesives are applied to 5E to 5E in advance.

Then, as shown in FIG. 4, the circular copper foils 5A to 5E are etched by a photo-etching method, and spiral copper foil coils 6A to 6A as desired conductor patterns are formed on the bottom surfaces of the circular concave grooves 3A to 3E. 6E are formed respectively. That is, a photoresist is applied to the upper surfaces of the annular copper foils 5A to 5E, the photoresist layer is exposed with a spiral pattern that circulates for several turns, and the portions other than the spiral pattern portion covered with the photoresist layer are removed by etching. Then spiral copper foil coil 6A
To 6E are formed respectively. In the case of FIG. 4, the spiral copper foil coils 6A to 6E are annular concave grooves 3A to 3E.
The number of turns varies depending on the groove width, and the wider the groove width, the greater the number of turns.

After that, the spiral copper foil coils 6A to 6
Solder plating is applied to the exposed portions of E to prevent copper corrosion, and final spiral coils are formed. In FIG. 5, the spiral coil 8A portion in which the solder plating layer 7 is applied to the exposed portion of the spiral copper foil coil 6A is shown in an enlarged manner, but the same applies to other copper foil coils.

From the above, the plurality of annular concave grooves 3A to 3A
A stator or a rotor of a rotary transformer having spiral coils each having a spiral copper foil coil 6A to 6E on which solder plating 7 is applied on the bottom surface of E is obtained. The stator and the rotor of the rotary transformer are arranged close to each other so that the surfaces on which the annular groove is formed face each other, the stator is fixed, and the rotor is set to be rotatable by being attached to the rotating shaft.

Although not shown in the drawing, through-holes penetrating from the bottoms of the annular recessed grooves 3A to 3E to the back surface of the ferrite core 1 are provided in the annular recessed grooves 3A to 3E of the disk-shaped ferrite core 1. They are formed in pairs,
The through hole serves as a lead-out end of each spiral coil.

According to the above-mentioned embodiments, the annular copper foil 5A which fits the shapes of the annular concave grooves 3A to 3E by the etching method.
To 5E are formed, the shape of the annular recessed grooves 3A to 3E can be easily accommodated, and a small ferrite core can also be accommodated. In addition, each spiral coil (which is plated on the spiral copper foil coils 6A to 6E) is processed into a desired conductor pattern by photoetching the above-mentioned circular copper foils 5A to 5E adhered to the bottom surfaces of the circular recessed grooves 3A to 3E. Since the coil is formed as described above, the number of windings and the line width of the coil can be freely set, and the density of the spiral coil can be easily increased, which is suitable for downsizing and thinning of the rotary transformer. further,
Since each of the above steps can be automated, it is suitable for mass production, and the manufacturing cost can be reduced.

The annular copper foils 5A to 5E can be formed by a punching method other than the etching method depending on the size of the annular concave grooves 3A to 3E and the required accuracy.

In the above embodiment, the disk-shaped ferrite core is provided with five annular recessed grooves, but the number of the annular recessed grooves can be appropriately changed according to the specifications of the rotary transformer. Similarly, the number of turns and the line width of the spiral coil can be appropriately changed according to the specifications of the rotary transformer. Also,
Although the copper foil is used as the annular conductor metal foil, other conductor metal foils may be used. Further, although solder is used as the plating material applied to the spiral copper foil coils 6A to 6E, other plating materials may be used.

Although the embodiment of the present invention has been described above, it is obvious to those skilled in the art that the present invention is not limited to this and various modifications and changes can be made within the scope of the claims. Let's do it.

[0026]

As described above, according to the method for manufacturing a rotary transformer of the present invention, at least one annular groove is provided on one surface of the disk-shaped magnetic core, and the annular conductor is formed in the annular groove. Since the metal foil is bonded and the conductor pattern is formed by the annular conductor metal foil by etching, the process can be automated, suitable for mass production, and the manufacturing cost can be reduced. In addition, the number of turns, the line width, and the like of the conductor pattern serving as the coil can be freely set, and the coil can be downsized or the density can be increased. Therefore, an inexpensive rotary transformer suitable for miniaturization and thinning can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing a disk-shaped ferrite core used in an example of a method for manufacturing a rotary transformer according to the present invention.

FIG. 2 is a sectional view showing a disk-shaped ferrite core.

FIG. 3 is a partial cross-sectional view showing a step of adhesively fixing an annular copper foil to the bottom surface of the annular concave groove of the disk-shaped ferrite core.

FIG. 4 is a partial cross-sectional view showing a step of forming a spiral copper foil coil on the bottom surface of the annular concave groove of the disk-shaped ferrite core by subjecting the annular copper foil to photoetching.

FIG. 5 is a partial enlarged cross-sectional view showing a step of forming a spiral coil by performing solder plating on the spiral copper foil coil.

[Explanation of symbols]

 1 Discoidal Ferrite Core 2 Through Hole 3A to 3E Circular Groove 5A to 5E Circular Copper Foil 6A to 6E Spiral Copper Foil Coil 7 Solder Plating Layer 8A Spiral Coil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichiro Kawamura 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Inventor Koji Kinoshita 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Within the corporation

Claims (2)

[Claims] 1. A disk-shaped magnetic core is provided with at least one annular groove on one surface thereof, an annular conductor metal foil is adhered to the annular groove, and a conductor pattern is formed on the annular conductor metal foil by etching. A method of manufacturing a rotary transformer, which comprises forming the rotary transformer. 2. The method for manufacturing a rotary transformer according to claim 1, wherein a plating layer is formed on the conductor pattern.