JPH06104122A - Rotary transformer - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a rotary transformer that is mounted as a signal transmission component of a rotary head cylinder and that can significantly reduce the cost without requiring highly accurate polishing. To do. [Structure] Winding groove 1 around which the signal coil 18 is wound on the outer peripheral surface
7 has an inner magnetic body 16 and a signal coil 2 on the inner peripheral surface.
At least one material of the outer magnetic body 21 having the winding groove 24 for winding 3 is made of resin ferrite.
When resin ferrites are used for both, the number of signal transmission systems is reduced, and when resin ferrites are used for only one, the magnetic permeability of the other sintered ferrite is increased. As a result, the structure can be configured without performing high-precision polishing without lowering the characteristic value, so that a significant cost reduction can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary transformer used as a signal transmission component of a rotary head cylinder such as a video tape recorder or a digital audio tape recorder.

[0002]

2. Description of the Related Art In recent years, magnetic recording / reproducing devices such as video tape recorders are highly competitive in price reduction. Therefore, cost reduction is strongly demanded for electronic parts used in magnetic recording / reproducing devices. The rotary transformer, which is one of them, is no exception.

A conventional rotary transformer will be described below. 7 and 8 are a plan view and a cross-sectional view of a conventional rotary transformer, 1 is a cylindrical inner magnetic body made of sintered ferrite with high accuracy and high magnetic permeability, and a plurality of windings are provided on the outer peripheral surface thereof. A groove 2 and a vertical groove 3 are formed. A signal coil 4 is wound around the winding groove 2, and a short ring groove 6 in which a short ring 5 for preventing crosstalk between the signal coils 4 is wound and housed is formed at a required position between the signal coils 4. Has been done.

A constant space 7 is provided on the outer circumference of the inner magnetic body 1.
A cylindrical outer magnetic body 8 made of sintered ferrite having high precision and high magnetic permeability is arranged so as to face each other, and a plurality of winding grooves 9 and vertical grooves 10 are provided on the inner peripheral surface of the outer magnetic body 8. The signal coil 4 of the inner magnetic body 1 is formed in the winding groove 9.
The signal coil 11 that faces is wound.

With such a structure, one of the inner magnetic body 1 and the outer magnetic body 8 is fixed and the other is rotated to transmit a signal between the signal coils 4 and 11.

Further, in such a rotary transformer, the signal is taken out from the inner magnetic body 1 as shown in FIG.
The terminal plate 13 having the terminal pins 12 is attached to the outer peripheral portion of the upper end of the terminal to connect the lead wire of the signal coil 4, and the terminal plate 15 having the terminal pins 14 is attached to the outer peripheral portion of the lower end of the outer magnetic body 8.
Was attached and the lead wire of the signal coil 11 was connected.

[0007]

However, in the above-mentioned conventional structure, since the sintered ferrite having high precision and high magnetic permeability is used for both the inner magnetic body 1 and the outer magnetic body 8, the polishing is performed to obtain the precision. There is a problem that it takes a lot of time to process and it is difficult to assemble it. That is, magnetic permeability μ =
About 60 to 60 is used for sintered ferrite.
The inner magnetic body 1 and the outer magnetic body 8 must be assembled so as not to cause misalignment so as to secure a slight gap 7 of μm, and therefore, highly accurate polishing and assembling are required. .

Particularly, the polishing cost is 60 to 7 of the material cost.
It accounts for 0%, which is a major impediment to cost reduction. When misalignment occurs, the characteristic value changes significantly as shown in FIG. 3, and the inner magnetic body 1 and the outer magnetic body 8 come into contact with each other. If one of them is rotating at a high speed, there is a problem of causing destruction.

The present invention eliminates the above-mentioned conventional drawbacks, and an object of the present invention is to provide a rotary transformer which does not require high-precision polishing and is inexpensive and free from misalignment.

[0010]

In order to solve the above problems, the present invention provides a cylindrical inner magnetic body having a plurality of winding grooves for winding a signal coil on the outer peripheral surface, and an outer periphery of the inner magnetic body. Is provided with an outer magnetic body having a plurality of winding grooves for winding the signal coil on the inner peripheral surface, and at least one of the inner magnetic body and the outer magnetic body is formed of a resin ferrite molded body. is there.

[0011]

With the above construction, since at least one of the magnetic bodies can be made of resin ferrite that is formed only without requiring polishing, it is possible to provide a rotary transformer that is inexpensive and has no misalignment.

[0012]

Embodiments of the rotary transformer of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing an embodiment of the rotary transformer of the present invention. 16 is an inner magnetic body made of resin ferrite, which is formed in a cylindrical shape and has two winding grooves 17 formed on the outer peripheral surface. And the winding groove 1 of this inner magnetic body 16
A signal coil 18 is wound around 7. Further, on the outer peripheral surface of the inner magnetic body 16, two vertical grooves (not shown) for drawing out the lead wire of the signal coil 18 are provided from the upper end to the lower end, and the signal coil 18 is wound. A short ring groove 20 around which a short ring 19 is wound to prevent crosstalk between adjacent signal coils 18 is provided between the line grooves 17.

Reference numeral 21 denotes an outer magnetic body made of a cylindrical resin ferrite, which is arranged on the outer circumference of the inner magnetic body 16 with a certain gap 22. The outer magnetic body 21 has an inner peripheral surface on which a signal of the inner magnetic body 16 is provided. Two winding grooves 24 around which the signal coil 23 is wound are formed at positions corresponding to the coils 18. Further, two vertical grooves (not shown) for drawing out the lead wire of the signal coil 23 are also formed on the inner peripheral surface.

The both magnetic bodies 16 and 21 are formed by molding using resin ferrite having a composition of 90% of sintered ferrite powder, 9.5% of polyphenylene stylate resin, and 0.5% of stabilizer. Therefore, in order to reduce the magnetic permeability of the material by using this resin ferrite, the number of wound signal coils 18 and 23 should be reduced to two to ensure the characteristic value of the signal transmission system. ing. Although two signal coils 18 and 23 are shown in the drawing, it is also possible to have three or more.

Next, another embodiment shown in FIG. 2 will be described. In this embodiment, the inner magnetic body 16 is made of sintered ferrite, the outer magnetic body 21 is made of resin ferrite, and the number of signal coils 18, 23 wound around the magnetic bodies 16, 21 is the same. With four winding grooves 17, 2
4 is also configured by 4 pieces each.

As shown in both of the above embodiments, when at least one of the inner magnetic body 16 and the outer magnetic body 21 is formed by molding resin ferrite, a conventional structure in which only sintered ferrite is formed in FIG. Compared to
Since the magnetic permeability of resin ferrite is low, the change in magnetic resistance due to misalignment is small, and therefore misalignment characteristics can be obtained in combination, and the mounting accuracy can be greatly eased compared to the conventional case.

Next, another embodiment shown in FIG. 4 will be described. This embodiment is a development of the embodiment shown in FIG. 1 and includes an inner magnetic body 16 made of resin ferrite.
Is provided with a protrusion 25 on a part of the upper end of the terminal pin 26 for connecting the lead wire of the signal coil 18 to the protrusion 25.
The terminal board is integrated with the plant. Further, a protruding portion 27 is provided on a part of the lower end of the outer magnetic body 21 made of resin ferrite, and a terminal pin 28 for connecting a lead wire of the signal coil 23 is planted on the protruding portion 27 to form a terminal plate integrated type. It was done.

In the embodiment shown in FIG. 4, each of the inner magnetic body 16 and the outer magnetic body 21 has four signal coils 18,
23 shows what is wound.

With the above-mentioned structure, it is not necessary to separately assemble the terminal plates into the magnetic bodies 16 and 21, so that the assembling property can be greatly improved and the cost can be further reduced. .

Next, the embodiment shown in FIGS. 5 and 6 will be described. 5 and 6, reference numeral 29 denotes a cylindrical inner holder, and inner magnetic members 16a, 16 formed on the outer peripheral surface of the inner holder 29 in a substantially semi-cylindrical shape by resin ferrite.
b is linked. These two inner magnetic bodies 16a, 1
A gap forming a vertical groove 30 is formed at the abutting portions at both ends of 6b. Also, the two inner magnetic bodies 16a, 1
A winding groove 17 around which a plurality of signal coils 18 are wound and a vertical groove 31 extending over the upper and lower ends are formed on the outer peripheral surface of 6b.

Further, 32 is a cylindrical outer holder, and outer magnetic members 21a and 21b made of a substantially semi-cylindrical resin ferrite molded body are joined to the inner peripheral surface of the outer holder 32. The abutting portions of both ends of the two outer magnetic bodies 21a and 21b are configured to be displaced by about 90 degrees from the abutting portions of the inner magnetic bodies 16a and 16b, and a gap serving as a vertical groove 33 is formed in the abutting portions. Has been formed. A winding groove 24 around which a plurality of signal coils 23 are wound is formed on the inner peripheral surfaces of the outer magnetic bodies 21a and 21b, and a vertical groove 34 for drawing out a lead wire for drawing out the signal 23 is formed.
Are formed.

The short ring groove 2 around which the short ring 19 is wound is formed on the outer peripheral surfaces of the inner magnetic bodies 16a and 16b.
0 is also formed.

The inner holder 29 and the outer holder 3 are also provided.
2 may be made of metal such as aluminum or synthetic resin such as polyphenylene stylate resin.

With the above structure, the inner magnetic bodies 16a, 16b and the outer magnetic bodies 21a, 21b can be molded more easily and can be manufactured at a low cost.

Although the inner magnetic bodies 16a and 16b and the outer magnetic bodies 21a and 21b are formed in a substantially semi-cylindrical shape, they may be formed in an arc shape obtained by dividing a cylinder into three or four parts. One of the magnetic bodies is a resin magnet,
The other may be made of sintered ferrite.

Further, in the above embodiment, both the inner magnetic bodies 16a and 16b and the outer magnetic bodies 21a and 21b are molded with resin ferrite, but only one of the inner magnetic body and the outer magnetic body is formed. The resin ferrite may be used, and the other one may be sintered ferrite.

[0028]

As described above, according to the present invention, since at least one of the inner magnetic body and the outer magnetic body is molded by using resin ferrite, highly precise polishing is not required, and it is possible to greatly improve the productivity. While reducing costs,
Since the magnetic permeability of resin ferrite is significantly lower than that of sintered ferrite, the magnetic resistance during assembly of the rotary transformer is less likely to change due to misalignment, and the effect of preventing characteristic differences due to misalignment is also obtained. be able to.

Further, as compared with the case where only sintered ferrite is used, the damage such as cracking and chipping is reduced, and the yield can be improved, which is a great industrial value.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a rotary transformer of the present invention.

FIG. 2 is a sectional view showing the other embodiment.

FIG. 3 is a characteristic diagram showing misalignment characteristics of the present invention and a conventional rotary transformer.

FIG. 4 is a sectional view of another embodiment of the present invention.

FIG. 5 is a plan view of still another embodiment of the present invention.

FIG. 6 is a sectional view of the same.

FIG. 7 is a plan view showing a conventional rotary transformer.

FIG. 8 is a sectional view of the same.

FIG. 9 is a sectional view showing another conventional example.

[Explanation of symbols]

 16, 16a, 16b Inner magnetic body 17 Winding groove 18 Signal coil 19 Short ring 20 Short ring groove 21, 21a, 21b Outer magnetic body 22 Air gap 23 Signal coil 24 Winding groove 25 Projection 26 Terminal pin 27 Projection 28 Terminal Pin 29 Inner holding body 30,31 Vertical groove 32 Outer holding body 33,34 Vertical groove

Claims (5)

[Claims] 1. A cylindrical inner magnetic body having a plurality of winding grooves for winding a signal coil on the outer peripheral surface, and a plurality of inner magnetic bodies arranged on the outer periphery of the inner magnetic body for winding the signal coil on the inner peripheral surface. A rotary transformer including an outer magnetic body having a winding groove, and at least one of the inner magnetic body and the outer magnetic body being a molded body of resin ferrite. 2. The rotary transformer according to claim 1, wherein the inner magnetic body is a sintered ferrite and the outer magnetic body is a resin ferrite molded body. 3. The rotary transformer according to claim 1, wherein a terminal plate having a terminal pin is integrally formed at an end of a magnetic body made of resin ferrite. 4. An inner magnetic body, which is formed as an inner magnetic body and an outer magnetic body, is formed by dividing the outer peripheral surface of an inner holding body into an arc shape, and is formed by dividing the inner magnetic surface of the outer holding body into an arc shape. 2. The rotary transformer according to claim 1, wherein the outer magnetic body is attached to the outer magnetic body, and at least one of the inner magnetic body and the outer magnetic body is made of resin ferrite. 5. The rotary transformer according to claim 4, wherein a vertical groove is formed in the abutting portion of the arcuate magnetic body attached to the holding body.