JPH03145107A - Rotary transformer - Google Patents

Abstract

PURPOSE:To make it possible to obtain a small-sized and highly reliable rotary transformer at a high yield rate with excellent productivity by a method wherein a core is formed with a magnetic part, consisting of magnetic material, and a non-magnetic part consisting of non-magnetic material, and a coil is arranged on the above-mentioned core. CONSTITUTION:Magnetic core parts 5, 6 and 7, to be formed as a frame body, are provided in the same number as the coil corresponding to the required channel number in such a manner that they are concentrically arranged on one side face 1a of a coil 1 at the prescribed intervals. Also, the above- mentioned magnetic core parts 5, 6 and 7 are provided with circular winding grooves 5a, 6a and 7a which will be used for arrangement of coils 2, 3 and 4, and the coils 2, 3 and 4 are provided in the above-mentioned winding grooves 5a, 6a and 7a. Besides, the cross-section of the magnetic core parts 5, 6 and 7 is formed almost in a horizontal U-shaped. A core 1 is formed by integrally molding the magnetic core parts 5, 6 and 7 and a non-magnetic core parts 8 by two-color molding using the same injection molding machine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary transformer used in a rotating magnetic head device such as a video tape recorder or a digital audio recorder.

(Summary of the Invention) The present invention provides a rotary transformer that transmits and receives signals between a circuit provided on a rotating side and a circuit provided on a stationary side, in which a magnetic path portion is made of a magnetic material and the other portions are made of a non-magnetic material. By using a color-molded core, the present invention aims to provide a rotary transformer that is small, highly reliable, and highly productive.

[Prior Art] A rotary transformer is a connection means for transmitting a signal obtained from a rotating magnetic head provided on the rotating side to a fixed side circuit in a rotating magnetic head device such as a video tape recorder or a digital audio tape recorder. It is widely used as

Generally, a rotary transformer is formed by fitting, for example, an annular coil into each S-wire groove provided concentrically on one side of a substantially disk-shaped magnetic core according to the number of channels. It consists of a rotor and a stator, which are arranged opposite to each other with a small gap between them. and,
Between each coil of the rotor provided on the rotating side and the stator provided on the stationary side! For example, a rotating magnetic head connected to the rotor and, for example, a reproducing circuit connected to the stator are connected by magnetic coupling to transmit video signals, digital audio signals, etc.

The above-mentioned rotor and stator are usually made by pressing magnetic powder such as ferrite using a mold or the like to form annular @ wire grooves in a concentric shape and at the same time forming an outer shape into a substantially disk shape.
This is formed by burning it out at a high temperature, and then fitting and arranging a coil produced in a separate process into the above-mentioned winding groove.

By the way, since the rotor and stator are made of magnetic material such as ferrite as mentioned above, mutual interference is likely to occur between the coils arranged in each winding groove, which may lead to noise generation and changes in inductance. There is. For this reason, conventionally, in order to prevent crosstalk between these channels, an annular groove was formed between adjacent winding grooves concentrically with these winding grooves, and an insulating wire material, that is, a short ring was formed here. I am trying to set it up.

However, if the short ring groove is provided in the magnetic core, the magnetic core will inevitably become larger, making it impossible to support video tape recorders and the like that require miniaturization. Therefore, in order to miniaturize the magnetic core, it is possible to make the intervals between the winding grooves and the short ring grooves as narrow as possible, but if they are too narrow, the wall thickness between the grooves will become too thin and the manufacturing process will be delayed. 9. Chips may occur, for example, when releasing a mold or installing a coil.

As a result, not only variations in inductance occur, but also yields and productivity deteriorate.

(T!l!1 that the invention seeks to solve) Therefore, the present invention has been proposed in view of such conventional circumstances, and includes:
The purpose of this invention is to provide a rotary transformer that is small and highly reliable, and further aims to provide a rotary transformer that has a high yield and excellent productivity.

[Means for Solving the Problems] The rotary transformer of the present invention has been proposed to achieve the above-mentioned object, and has a magnetic path portion made of a magnetic material and a non-magnetic portion made of a non-magnetic material. It is equipped with a core formed by color molding, and a coil is disposed on the core.

In the present invention, a core in which the magnetic path portion is formed of a magnetic material and the other portion is formed of a non-magnetic material is produced by two-color molding. Two-color molding is a technique widely used in, for example, molding of cassette halves, in which the magnetic path portion and the non-magnetic portion are molded using different molding materials using the same injection molding machine. That is, a Φ mold for two-color molding is first arranged to correspond to the shape of the magnetic path portion and the magnetic material is injected, and then the mold is moved to match the shape of the non-magnetic portion and the non-magnetic material is injected. As a result, the magnetic path portion and the non-magnetic portion are integrally formed using the same injection molding machine. Note that depending on the structure of the mold, the non-magnetic portion may be injection molded first, and then the magnetic path portion may be injection molded.

In the core obtained by injection molding, the magnetic powder is pressurized evenly in all directions within the mold, so there is little residual stress, and the distribution of packing density is homogeneous, preventing the occurrence of cracks. suppressed. Furthermore, since injection molding is a molding method that allows the production of very fine shapes, it is suitable for molding cores with complex shapes.

By the way, as the magnetic material constituting the magnetic path portion, a kneaded mixture of magnetic powder and polymeric material can be used.

As the magnetic powder, for example, Mn that has been sintered into spinel
-Zn ferrite-, Ni-Zn ferrite, Ni-C
Metal oxide powders such as u-Zn, metal powders such as iron and nickel, or metal alloy powders such as carbonyl iron and sendust can be used, and these may be used alone or in combination of two or more. Among these, metal oxide powders such as Mn-Zn ferrite and Ni-Zn ferrite are particularly suitable.

On the other hand, thermoplastic resin is suitable as the polymer material.

Such thermoplastic resins include, for example, polypropylene,
Polyethylene, polyamide, polycarbonate, polybutadiene terephthalate, polyphenylene sulfide, polystyrene, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, polyethylene terephthalate, polymethyl methacrylate, polyacetal, polytetrafluoroethylene, polyvinyl acetate, polyvinyl butyral, Vinyl chloride/hinyl acetate copolymer, polychlorotrifluoroethylene, diallyl phthalate resin, polyisobutylene, polyurethane, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, styrene butadiene, thermotropic liquid crystal Examples include resin.

It is preferable to mix a lubricant and a plasticizer into the mixed material made of these materials in order to improve fluidity during molding.

Examples of lubricants include cadmium stearate, cadmium laurate, cadmium ricinoleate, cadmium naphthenate, cadmium 2-ethylhexoate, barium stearate, barium laurate, barium ricinoleate, barium naphthenate, and 2-ethylhexoin. barium acid, calcium stearate, calcium laurate, calcium ricinoleate, zinc stearate,
Examples include metal soaps such as zinc laurate, zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, lead naphthenate, tin stearate, and magnesium stearate. Among these, barium stearate, calcium stearate, zinc stearate, lead stearate, and magnesium stearate are more preferred.

Plasticizers include dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, butyl lauryl phthalate,
Examples include phthalic acid lubricants such as ditridecyl phthalate and butylbenzyl phthalate, and phosphoric acid lubricants such as tricresyl phosphate and trioctyl phosphate.

Further, a coupling agent may be used for the purpose of improving the adhesion between the magnetic powder and the thermoplastic resin.

Suitable examples of the coupling agent include titanate coupling agents and silane coupling agents.

On the other hand, as the non-magnetic material, for example, a mixture of non-magnetic ferrite powder and a polymer material, a mixture of ceramic powder and a polymer material, etc. can be used, or a polymer material alone may be used. As the polymer material, any of those mentioned above can be used.

In the above case, the magnetic path portion is formed using, for example, magnetic powder that has been turned into spinel from the bottom of a mine, and is used as the core of a rotary transformer as it is, but is not limited to this, for example, magnetic powder that has not been turned into spinel The magnetic path portion may be formed using powder, which is later fired to form a magnetic material. In this case, it is desirable to use a material for the non-magnetic portion that has a thermal shrinkage rate comparable to that of the magnetic path portion, and for example, it is preferable to use Cera ξ/Nx powder or the like.

[Effect]

In the rotary transformer of the present invention, since the core is composed of a magnetic path portion made of a magnetic material and a non-magnetic portion made of a non-magnetic material, the non-magnetic portion is connected to the coil disposed in each of these magnetic path portions. prevent mutual interference between

In addition, the core is formed by two-color molding, which allows the magnetic path part and the non-magnetic part to be integrally molded using the same injection molding machine, so the gap between the magnetic path part and the non-magnetic part can be extremely narrow. However, this part will not be damaged.

〔Example〕

Hereinafter, specific embodiments to which the present invention is applied will be described with reference to the drawings.

The rotary transformer of the present invention, as shown in FIG.
It is composed of a substantially disk-shaped core (1) and coils (2), (3), and (4) disposed in the core (1).

The core (1) consists of a magnetic path portion made of magnetic material and a non-magnetic portion made of non-magnetic material, and these magnetic path portion and non-magnetic portion are integrally molded by two-color molding. .

In this example, Mn, which is made into spinel by firing into a magnetic material, is used.
- A kneaded product obtained by kneading Zn ferrite into a binder was used, and a kneaded product obtained by kneading a non-magnetic ceramic powder and a polymer material as a non-magnetic material was used. The proportions of the magnetic powder and the binder at this time were 91% by weight and 9.1% by weight, respectively. The reason for specifying it in this way is to simultaneously satisfy the i3m ratio and kneadability.

As shown in FIG. 2, the magnetic path portion is a portion in which the annular coils (2), (3), and (4) are disposed, and is formed in an annular shape as a frame with a substantially U-shaped cross section. has been done. A magnetic core portion (5) formed as the frame body (
6).

(7) are provided in the same number as the number of coils corresponding to the required number of channels (3 channels in this example), and are arranged concentrically at predetermined intervals on the negative side surface (1a) of the core (1). It is provided. In addition, these magnetic core parts (5)
, (6), <7) is the above coil (2),
(3).

(4) An annular winding groove (5a) for arranging the winding groove (5a),
(6a).

(7a), and these winding grooves (5a),
Coils (2) and (3) in (6a) and (7a)
, (4) are arranged to form a magnetic path. In addition, the above magnetic core parts (5) and (6)
, (7) winding grooves (5a), (6a), (7)
It is sufficient for the thicknesses T, T2 of both side walls where a) is formed to be approximately 0.511III because of the need to ensure the cross-sectional area of the magnetic path.

In the above example, the magnetic core parts (5), (6), (
7) has a substantially U-shaped cross-section, but as shown in FIG. 3, for example, these magnetic core parts (5), (
6), both side walls of (7) (5b), (5c),
(6b), (6c), (7b), (7c
) may be inclined to have a substantially trapezoidal cross-sectional shape. In this way, the magnetic core parts (5), (6),
Both side walls of (7) (5b), (5c), (6b
), (6c), (7b), and (7c) form a so-called reverse taper with respect to the non-magnetic core portion (8) described below, and the magnetic core portions (5), (6), (7) and the non-magnetic core The connection with part (8) becomes more reliable.

Therefore, the magnetic core parts (5), (6), (7
) will not be removed from the non-magnetic core portion (8).

On the other hand, the non-magnetic portions include the magnetic core portions (5) and (6).
).

This is the part excluding (7). That is, the non-magnetic core part (8) excluding these magnetic core parts (5), (6), <7) is the magnetic core part (5), (6), (
An annular groove (9) with a substantially rectangular cross section corresponding to the shape of 7),
(10) and (11) are provided concentrically on the - side (la) to form a substantially disk shape.

In the core (1) formed in this way, the annular grooves (9) and (1
0) and the annular grooves (10) and (11), the respective partition walls (8a) and partition walls (8b) are arranged in the magnetic core portions (5), (6) and (7). 2)
, (3), and (4) to prevent mutual interference. That is, the partition wall (8a)
, (8b) is formed from a non-magnetic material, so it functions similarly to a short ring and prevents crosstalk between channels. The core (1) also includes magnetic core parts (5), (6), (7) and a non-magnetic core part (8).
) can be integrally molded in the same injection molding machine, so the partition wall (8a)
, (8b), not only can the thickness T, , T, be made extremely thin, but also sufficient strength can be obtained in this part, so that it will not break.

Note that the thicknesses Tx and Ta of the partition walls (8a) and (8b) are
If it is about 0.1 mm, it is sufficient in terms of strength and prevention of crosstalk.

Therefore, in the core (1) of this embodiment, there is no need for a short ring, there is no need to provide a short ring groove for arranging this, and the thickness of the partition wall for preventing crosstalk is made extremely thin. what you can do,
At the same time, it is possible to reduce the size of the transformer, and at the same time, provide a highly reliable rotary transformer that is free from damage.It is also possible to reduce the number of parts and manufacturing processes, and to expect a significant improvement in productivity.

By the way, in order to manufacture a rotary transformer using the magnetic core (1) stolen as described above, the magnetic core (1) is arranged facing each other with a small gap on the rotating side and the stationary side. Ru.

A rotary transformer configured in this way transmits video signals and digital signals through electromagnetic coupling between the coils of the magnetic core (rotor) placed on the rotating side and the magnetic core (stator) placed on the stationary side. It is designed to transmit audio signals, etc.

As described above, in this embodiment, the present invention was applied to a so-called flat rotary transformer in which substantially disk-shaped cores are arranged facing each other with a small gap. The present invention can also be applied to a so-called vertical rotary transformer in which the rotary transformers are arranged facing each other.

For example, as shown in FIG. 4, the number of coils (in this example, 7 The magnetic core part (13
) are formed into an annular shape and are arranged at predetermined intervals in the height direction by two-color molding of the non-magnetic core part (12) and the magnetic core part (13) to produce an outer core (14). .

On the other hand, as shown in FIG. 4, the core (16) provided on the inside is the outer wall (
These non-magnetic core parts (
17) and the magnetic core part (18) are produced by two-color molding.

In this way, the adjacent magnetic core parts (13), (
Crosstalk between the coils (15) and (19) arranged in the magnetic core parts (13) and (18)
) are prevented by the non-magnetic core parts (12) and (17) that separate them. Also, this core (14), (16)
Needless to say, a small and highly reliable rotary transformer can be provided in the same manner as in the above embodiment.

[Effects of the Invention] As is clear from the above description, in the rotary transformer of the present invention, the non-magnetic portion serves as a short ring, so crosstalk between channels can be prevented without using the short ring. In addition, short ring groove machining can be eliminated.

Therefore, it is possible to provide a highly reliable rotary transformer that can be made smaller, reduce the number of parts, and be free from damage.

In addition, in the rotary transformer of the present invention, the magnetic path part and the non-magnetic part are integrally molded by two-color molding, so the core can be manufactured with a high yield just by molding, which greatly simplifies the manufacturing process. It is possible to improve productivity as well as improve productivity.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing one embodiment of a rotary transformer to which the present invention is applied, Fig. 2 is an enlarged sectional view of the core, and Fig.
The figure is an enlarged sectional view showing another example of the core, and FIG. 4 is an enlarged sectional view showing another example of the rotary transformer to which the present invention is applied. 1.14.17 ... Core 2.34 ... Coil

Claims (1)

[Claims] A rotary transformer comprising a core formed by two-color molding of a magnetic path part made of a magnetic material and a non-magnetic part made of a non-magnetic material, and a coil arranged in the core.