JPS5866314A - Rotary transformer - Google Patents

Abstract

PURPOSE:To contrive the improvement of magnetic characteristics and magnetic efficiency by a method wherein a finely split magnetic film having higher initial permeability than the initial permeability of a substrate is provided at the opposite face of a rotary section and a fixed section. CONSTITUTION:A rotary transformer is composed of a rotor 8 and a stator and both of them are faced with a slight interval each other. A finely split magnetic film 15 having higher initial permeability than that of a core 1 is formed on the core 10 of this rotor 8. In this way, the improvement of magnetic characteristics can be contrived. This film 15 is also coated with an insulating layer 16. Furthermore, windings 17, 18 are provided in spiral shape on the upper face of the layer 16. The eddy current is split and is remarkably reduced by providing such the finely split magnetic film on a substrate. Therefore, the frequency dependence on the permeability can remarkably be improved and the magnetic coupling factor with a fixed section and a rotary section can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method of attaching a pair of substrates made of a magnetic material and provided with windings to a rotating part and a fixed part, respectively, and arranging the pair of substrates and the windings to face each other. The present invention relates to a rotary transformer that transmits signals between a part and the fixed part without contact, and is particularly suitable for use in a rotating head drum of a VTR.

The rotary head drum of a VTR is provided with a rotary transformer for transmitting recording signals and reproduction signals between the rotary drum and the fixed drum without contact. A rotary transformer uses magnetic inclination, and Figure 1 shows the transformer core (
1) shows a cross-sectional view of FIG. Note that the transformer core (1) shown in FIG. 1 is provided on the fixed drum side, and the same core is provided facing the rotating drum side, thereby forming a rotary transformer.

The rotary transformer core (1) shown in FIG. 1 is made of, for example, a ferrite material and molded into an annular shape, and has two concentric grooves (2) and (3) formed on its surface for mounting a coil. This transformer core (1) is fixed concentrically to the stationary drum and the rotating drum, respectively. Annular windings (4) and (5) for the A head and B head are mounted in these coil mounting grooves (2) and (3), respectively.

The reason why ferrite material is used as the transformer core (1) is that ferrite material has high magnetic permeability and good frequency characteristics.

The characteristics of rotary transformers and ferrites commonly used at present are as shown in Tables 1 and 2 below.

However, in the conventional two-channel rotary transformer, at least one
It is necessary to have a facing area of 50 mm2 or more. Note that the opposing area refers to the area of the magnetic path corresponding to each channel, and can be simply expressed as the area between the first channel winding and the second channel winding (indicated by the diagonal line S in Figure 2). (area of the part shown in ). For this reason, it is difficult to reduce the outer diameter of the rotary transformer to a diameter of 30 mm or less.

By the way, in order to cope with the miniaturization and multichannelization of rotary transformers, ferrite materials, which are currently used as transformer cores, are used.
Furthermore, a rotary transformer with a facing area of 100 mm2 or less is required.

However, with the shape and material of the conventional rotary transformer (in the case of 2 channels), its outer diameter is 20 m in diameter.
The reality is that it is extremely difficult to reduce the value to m or less in terms of characteristics.

The present invention was invented in view of the above-mentioned circumstances, and uses ferrite material as a transformer core, and provides divided magnetic films on the opposing surfaces of the rotating part and the fixed part, thereby improving magnetic time and magnetic properties. The present invention aims to provide a rotary transformer that can improve efficiency, be smaller in size, and have multiple channels.

An embodiment in which the present invention is applied to a rotary transformer used in a rotary head drum of a VTR will be described below with reference to FIGS. 3 to 10.

As shown in Fig. 3, the rotary transformer of this embodiment has a rotor (rotating part) (8) and a stator (fixed part) as in the conventional case.
(9). Note that the rotor (8) is disposed on the lower surface of a rotating drum (not shown), while the stator (9)
) are arranged on the upper surface of the stationary drum, and both face each other with a small gap between them. These rotor (8) and stator (9) have a core made of ferrite (
10) and (11), respectively, and these cores (10
) (11) are formed with through holes (12) and (13) each having a circular cross section, into which the rotating shaft is inserted.

Next, the structures of the rotor (8) and stator (9) will be explained in more detail, but since the structures of both are the same, the structure of only the rotor (8) will be explained here, and the structure of the stator (9) will be explained in more detail. Explanation regarding this will be omitted.

First, as shown in FIGS. 3 and 5, the rotor (8)
A divided magnetic film (15) made of permalloy, sendust, alperm, etc. having a higher initial magnetic permeability than ferrite and having a thickness of 5 to 10 μm is formed on the core (10). The reason why the magnetic film (15) made of a magnetic material having an initial magnetic permeability higher than that of ferrite is provided on the ferrite core is to improve the magnetic properties. However, when this magnetic film (15) is formed uniformly, the specific resistance of the magnetic film (15) is small (20
50 μΩcm), the frequency characteristics of magnetic permeability deteriorate due to eddy current loss. Therefore, in this embodiment, in order to increase the apparent resistivity and reduce the eddy current loss, the seventh
As shown in the figure, for example, several micrometers (for example, 2 micrometers) in concentric circles.
) is divided in the order of . The reason why the divided width of the magnetic film (15) is on the order of several μm is that the skin depth of the magnetic film has frequency dependence as shown in FIG.

Moreover, as shown in FIG. 5, this magnetic film (15) is made of SiO2
It is covered with an insulating layer (16) consisting of etc. Further, on the upper surface of this insulating layer (16), windings (17) and (18) are provided on concentric circles, and these windings (17) (
18) are each formed in a spiral shape. Further, an insulating layer (19) is formed on the upper surface of the above-mentioned insulating layer (16), and this insulating layer (19) forms the windings (17) (18).
) are each coated. In addition, both ends of the winding wire (17) and both ends of the winding wire (18) are marked with the marks shown in FIGS. 4 to 6.
As shown in the figure, thin film electrodes (21a), (21b), and (22a) provided by vapor deposition, sputtering, etc.
(22b) are electrically connected. That is, the fifth
As shown in the figure, the valley lead portions (23a) to (24b) of the electrodes (21a) to (22b) are connected to the window portions (24b) of the insulating layer (19).
It is connected to both ends of the winding wire through the core (10), and the other end has an electrode plate part (10) located away from the core (10).
25a) to (26b) are formed. Although not shown, the two terminals of the A head are connected to the above-mentioned electrode plate part (2).
5a) and (25b) respectively by lead wires, and the two terminals of the B head connect 1 to the electrode plate part (26a).
) and (26b) respectively by lead wires.

In order to prevent the adhesion of dust and short circuit between the electrodes (21a) to (22b), the electrode (21a) is covered with a protective film (27) (see FIG. 9G) made of Si3-4, SiO2, etc. ) to (22b) are coated.

The procedure for manufacturing the rotary transformer configured as described above will be explained.

First, a ferrite substrate is processed into a disk shape, and then, as shown in FIG. 9A, a thin magnetic film (made of permalloy, sendust, alperm, etc.) made of permalloy, sendust, alperm, etc. 15) is formed uniformly. Thereafter, this magnetic film (15) is divided into concentric circles, for example, in units of several μm (for example, 2 μm), as shown in FIGS. 7 and 9B, using a fine processing technique such as dry etching. Next, an insulating layer (16) made of SiO2 or the like is formed on the ferrite substrate (10) as shown in FIG. 9C, and the above-described divided magnetic film (15) is covered with this insulating layer (16). . After this, Figures 4 and 9
As shown in Figure D, spiral windings (17) and (18) are formed concentrically at predetermined locations on the upper surface of the insulating layer (16) by vapor deposition, sputtering, or the like.

Further, as shown in FIG. 9E, the windings (17) and (18) are covered with an insulating layer (19) made of SiO2 or the like.

Next, as shown in FIG. 9F, conductive electrodes (21a) to
(22b) and the windings (17) and (18)
One ends of the lead parts (25a) to (24b) of the electrodes (21a) to (22b) are electrically connected through windows (20) provided at locations of the insulating layer (19) corresponding to both ends of the electrodes (21a) to (22b). do. Finally, cover the electrodes (21a) to (22b) with a protective film (
27).

According to the rotary transformer configured as described above, the upper surface of the ferrite core (10) is made of a magnetic material such as permalloy, sendust, or alperm, which has a higher initial magnetic permeability than ferrite, and is divided into pieces on the order of several μm (for example, 2 μm). Since the magnetic film (15) is provided, it is possible to improve magnetic properties and magnetic efficiency. That is, as is clear from the graph of FIG. 10, which shows the frequency dependence of magnetic permeability of conventional ferrite, a uniformly formed magnetic film, and a divided magnetic film, in the case of a divided magnetic film,
Very high magnetic permeability is maintained over a wide frequency band. Therefore, the coupling coefficient of the rotary transformer can be increased. Furthermore, since the magnetic film is divided, the substantial facing area (surface area) of the rotary transformer can be increased. Therefore, even if the facing area of the ferrite core (10) is made small, predetermined characteristics can be obtained.

As a result, it becomes possible to downsize the rotary transformer and increase the number of channels.

In addition, in this example, the windings (17) (18) and the electrodes (
By configuring 21a) to 22b with thin conductive films, it is possible to reduce eddy current loss, thereby further increasing the overall magnetic efficiency.

Further, FIG. 11 shows a second embodiment of the present invention, in which both the windings (17) and (18) and the divided magnetic film (15) are connected to the ferrite core (10
) and these windings (17) (18)
are arranged between predetermined divided magnetic films. Note that in this case as well, the winding wire (
17) An insulating layer (18) that insulates the magnetic film (15)
16) is formed, and one end of the lead portions (25a) to (24b) of the electrodes (21a) to (22b) is connected to the winding wire (17) through the window (20) provided in the insulating layer (16).
(18) are respectively connected to both ends.

Then, the protective film (27) is applied to the electrodes (21a) to (22).
b) is coated.

Even in the case of the configuration as described above, the same operation and effect as in the first embodiment described above can be achieved.

Although the present invention has been described above with reference to Examples, the present invention is not limited to these Examples, and various modifications and changes can be made based on the technical idea of the present invention.

For example, in the embodiments described above, the magnetic film (15) has a concentric divided pattern, but it may also have a lattice pattern as shown in FIG. 12, or a radial pattern as shown in FIG. . Further, as shown in FIG. 14, a dividing pattern may be a combination of a grid pattern and a radial pattern, and it is also possible to employ various other dividing patterns.

As described above, the present invention provides a method in which a pair of substrates made of a magnetic material and provided with a winding are attached to a rotating part and a fixed part, respectively, and the pair of boards and the winding are arranged opposite to each other. In the rotary transformer, the rotary transformer is configured to transmit signals between the substrates without contact, and the opposing surface of at least one of the pair of substrates has an initial magnetic permeability higher than the initial magnetic permeability of the substrate and a plurality of partitions. A magnetic film is formed which is subdivided into two, and the winding wire and the magnetic film are arranged in a state where they are insulated from each other. Therefore, according to the present invention, since a magnetic film with high magnetic permeability and finely divided into many sections is provided on a magnetic material substrate,
Eddy currents are separated and eddy current losses are significantly reduced. Therefore, the frequency dependence of magnetic permeability can be greatly improved,
The magnetic coupling coefficient between the fixed part and the rotating part can be increased. Moreover, since the magnetic film is divided, the substantial facing area (surface area) of the rotary transformer can be increased. As a result, even if the facing area of the magnetic base material is reduced, predetermined characteristics can be obtained, and as a result, the rotary transformer can be significantly downsized and multi-channeled.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional rotary transformer core for a VTR, FIG. 2 is a plan view of the same, and FIGS. 3 to 10 are for explaining a first embodiment of the present invention. 3 is an assembled vertical sectional view of the rotary transformer of the present invention, FIG. 4 is a plan view of the rotor of the rotary transformer, FIG. 5 is a partially enlarged sectional view for explaining the structure of the rotor, and FIG. 6 is a winding Fig. 7 is a plan view showing the connection relationship between wires and electrodes, Fig. 7 is a plan view showing the divided shape of the magnetic film deposited on the ferrite core, and Fig. 8 is the relationship between permalloy skin depth and frequency. 9A to 9G are cross-sectional views showing the procedure for manufacturing a rotary transformer according to an embodiment of the present invention.
The figure is a graph showing the frequency dependence of magnetic permeability of ferrite, a uniformly formed magnetic film, and a divided magnetic film. Fig. 11 is a cross-sectional view similar to Fig. 5 showing the second embodiment of the present invention. , and FIGS. 12 to 14 are plan views showing modified examples of the division pattern of the magnetic film, respectively. In addition, in the symbols used in the drawings, (8)...Rotor (9)...Stator (10) (11)...Ferrite core (15)...
Magnetic film (16)... Insulating layer (17) (18)... Winding wire. Agent Masaru Tsuchiya Figure 1 2 3 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Frequency fL <MHz) Figure 10 Frequency (Mlh) Figure 9 Figure 1 □ Figure """" ”′°°−”°°“°°′. (Spontaneous) Procedural Amendment Director-General of the Japan Patent Office 1, Indication of Case F@1561F-Patent Application No. 164669 2, Relationship with Title of Invention Case Patent Applicant Coro The number of inventions increased by the amendment?, ?i@IE'')" 1 Detailed description of the invention in the specification - and Drawing 8, contents of the amendment (1), page 4 of the specification, Table 2J [ Correct specific resistance PJ to "specific resistance p". (2), same page 4, line 3 "Opposing area J of 150- or more
Correct it to "the opposing area in each channel of 150- or more" 〇(3), page 7, lines 13-15, "...
It is formed in... '' are provided concentrically as shown in FIG. ” I am corrected. C41, 4th drawing! i! J. Amend Figures 5 and 6 as attached. 1 or more - No 4 Sword 2 1 No. 5 Figure 5 Figure 6

Claims (1)

[Claims] A pair of substrates made of a magnetic material and provided with a winding are attached to a rotating part and a fixed part, respectively, and the pair of boards and the winding are arranged to face each other, and a signal is transmitted between the rotating part and the fixed part. In a rotary transformer for contactless transmission, at least one of the pair of substrates has an inner surface having an initial magnetic permeability higher than the initial magnetic permeability of the substrate and is subdivided into a large number of sections. What is claimed is: 1. A rotary transformer characterized in that a magnetic film is formed therein, and the winding wire and the magnetomotive film are arranged in a mutually insulated state.