JPH0851039A - Rotary transformer - Google Patents

Abstract

PURPOSE:To suppress mixing of noise into a signal being transmitted by arranging annular conductive members farther on the outer circumferential side of an outermost signal transmission coil and/or farther on the inner circumferential side of an innermost signal transmission coil. CONSTITUTION:The rotary transformer comprises a pair of magnetic disc cores 61a, 61b having air core parts 60a, 60b facing each other through a gap (g) of about several tens mum. Two channel signal transmission coils 71a, 71b, 72a, 72b and short rings 8a, 8b for reducing interchannel crosstalk are arranged on the facing surfaces. Annular conductive thin films 91a, 91b of several mum thick made of Cu, for example, are arranged farther on the outer circumferential side of the signal transmission coils 72a, 72b arranged on the outer circumferential side. Since a leakage flux intruding into the magnetic cores 61a, 61b is shielded by the annular conductive thin films 91a, 91b and does not reach the signal transmission coils 72a, 72b, noise voltage is not induced.

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 for transmitting a recording / reproducing signal in a magnetic recording device such as a video tape recorder (hereinafter abbreviated as VTR) having a rotary magnetic head device.

[0002]

2. Description of the Related Art A general sectional structure of a rotary magnetic head device for a VTR is shown in FIG. In FIG. 3, 1 is a fixed drum, 2 is a support shaft fixed to the fixed drum by bearing means, 3 is a rotary drum rotatably supported by bearing means of the support shaft, and 4 is a rotary drum. The fixed magnetic head 5a is a magnet rotor fixed to the supporting shaft by a motor constituent member for rotating the rotary drum, 5b is a motor stator fixed to the fixed drum by the motor constituent member, and 6a is A rotary rotary transformer attached to the rotary drum and a fixed rotary transformer 6b fixed to the fixed drum.

FIG. 4 shows a sectional structure of the rotary transformers 6a and 6b. This rotary transformer has an air core 60
a pair of disc-shaped magnetic cores 61a, 61 having a, 60b
b are opposed to each other with a gap g of several tens of μm between the plate surfaces, and two channel signal transmission coils 71a, 71
b, 72a, 72b and short rings 8a, 8b for reducing crosstalk between channels are arranged.

By the way, miniaturization and weight reduction of magnetic recording devices such as VTRs are being promoted, and accordingly, the distance between the drum rotating motor and the rotary transformer arranged in the rotary magnetic head device is increased. When it becomes smaller, there arises a problem that the magnetic flux leaking from the core of the motor stator enters the core of the rotary transformer to induce a noise voltage in the coil for signal transmission of the rotary transformer.

To solve this problem, Japanese Patent Laid-Open No. 4-21631
Japanese Unexamined Patent Publication No. 6 discloses a technique of arranging a member having high magnetic permeability between a rotary transformer and a drum rotating motor. However, this configuration not only increases the number of parts but also downsizes the device. It goes against the trend.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and is caused by a magnetic flux leaking from a drum rotating motor in a signal being transmitted between rotary transformers. It suppresses the mixing of noise.

[0007]

In the disk-shaped rotary transformer according to the present invention, a ring-shaped rotary transformer is provided on the outermost side of the outermost signal transmission coil and / or on the innermost side of the innermost signal transmission coil. A conductive member is arranged, and in the cylindrical rotary transformer according to the present invention, an annular conductive member is arranged above the uppermost signal transmitting coil and / or below the lowermost signal transmitting coil. It

[0008]

According to the rotary transformer of the present invention, even if the leakage magnetic flux from the core of the motor stator enters the core of the rotary transformer, the leakage magnetic flux is shielded by the annular conductive member and is transmitted to the signal transmission coil. The noise voltage is not induced because the noise voltage is not reached.

[0009]

1 is a sectional view showing the structure of a rotary transformer according to an embodiment of the present invention. This rotary transformer has an air core 6
A pair of disc-shaped magnetic cores 61a, 6 having 0a, 60b
1b faces each other with a gap g of several tens of μm between the plate surfaces,
Two-channel signal transmission coils 71a, 7 are provided on the facing surface.
1b, 72a, 72b and short rings 8a, 8b for reducing crosstalk between channels are arranged, and Cu is further provided on the outer peripheral side of the signal transmitting coils 72a, 72b on the outer peripheral side.
A ring-shaped conductive thin film 9 made of a conductive material such as
1a and 91b are arranged. The annular conductive thin films 91a and 91b are the core 61a of the rotary transformer,
It is formed on the facing surface of 61b by a vacuum deposition method, a sputtering method, or the like.

Now, the effect of noise reduction by the annular conductive thin films 91a and 91b will be described with reference to the rotary magnetic head device shown in FIG.

In the rotary magnetic head device, when a motor drive circuit (not shown) operates to energize the coil of the motor stator 5b, magnetic flux is induced in the core of the motor stator, and the magnetic flux of the motor stator is generated. It also leaks to the outside. Since this leakage magnetic flux has a property of passing through a substance having a high magnetic permeability, the cores 61a and 61b of the rotary transformer are
In the conventional rotary transformer in which the annular conductive thin film is not provided, the leakage magnetic flux reaches the signal transmission coils 72a and 72b and induces a noise voltage in the coils. On the other hand, in the rotary transformer according to the present invention, the leakage magnetic flux penetrating the cores 61 and 61b is shielded by the annular conductive thin films 91a and 91b, and the leakage magnetic flux is transmitted to the signal transmission coil 72a and the signal transmission coil 72a.
Since it does not reach 72b, no noise voltage is induced.

As another embodiment of the present invention, the annular conductive thin films 91a and 91b may be replaced with annular conductive wires 92a and 92b as shown in FIG.

On the other hand, depending on the relative arrangement of the motor and the rotary transformer, the leakage magnetic flux may enter from the inner peripheral side of the rotary transformer. In that case, the annular conductive thin film or the annular conductive wire is introduced. It is effective to arrange the innermost circumference of the rotary transformer. Further, it is effective to dispose the ring-shaped conductive thin film or ring-shaped conductive wire on the outermost circumference and the innermost circumference of the rotary transformer against the leakage magnetic flux entering from the outer circumference side and the inner circumference side of the rotary transformer. is there.

Further, in the case of a cylindrical rotary transformer, the ring-shaped conductive thin film or the ring-shaped conductive wire is further provided above the uppermost signal transmission coil and / or further below the lowermost signal transmission coil. It is effective to place it on the lower side.

[0015]

According to the present invention, it is possible to suppress the external noise to the signal being transmitted through the rotary transformer without adding a new component.

[Brief description of drawings]

FIG. 1 is a sectional view of a rotary transformer according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a rotary transformer according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a rotary magnetic head device incorporating a rotary transformer according to an embodiment of the present invention and a conventional example.

FIG. 4 is a cross-sectional view of a conventional rotary transformer.

[Explanation of symbols]

61a, 61b Rotary transformer magnetic cores 71a, 71b Rotary transformer signal transmission coil (inner peripheral side channel) 72a, 72b Rotary transformer signal transmission coil (outer peripheral side channel) 8a, 8b Short for reducing crosstalk between channels Rings 91a, 91b Ring-shaped conductive thin films 92a, 92b Ring-shaped conductive wires

Claims (3)

[Claims] 1. In a disk-shaped rotary transformer, an annular conductive member is arranged on the outer peripheral side of the outermost signal transmission coil and / or on the inner peripheral side of the innermost signal transmission coil. This is a rotary transformer. 2. In a cylindrical rotary transformer, an annular conductive member is arranged above the uppermost signal transmission coil and / or below the lowermost signal transmission coil. A rotary transformer. 3. The rotary transformer according to claim 1, wherein the annular conductive member is made of a conductive thin film.