JP2594945B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus using a superconducting quantum interferometer, and in particular, a magnetic recording / reproducing apparatus capable of detecting weak signals and signals from a magnetic head with high sensitivity. About.

[Conventional technology]

The development of high-density magnetic recording has been remarkable, and in recent years, research on perpendicular magnetic recording suitable for high-density magnetic recording has progressed. In conventional in-plane magnetic recording, recording density has also increased due to improvements in magnetic heads and recording media. I have.

When linear recording density and track density are increased,
Since the area of the recording medium per bit or per wavelength decreases, the reproduction output decreases. It has been clarified that when recording is performed by perpendicular magnetic recording, signals with a linear recording density of up to 500 KBPI can be recorded. (No. 10
Proceedings of the Annual Meeting of the Japan Society of Applied Magnetics (1986), p.335) [Problems to be Solved by the Invention] When this recorded signal is reproduced, the magnetic flux generated from the signal magnetization of the medium is weak. However, there is a problem that the output is significantly reduced as compared with the low recording density.

The present invention solves such a problem, so that a recording signal having a very high linear recording density and track density can be reproduced.
It is an object of the present invention to provide a magnetic recording / reproducing apparatus having extremely sensitive detection means.

[Means for solving the problem]

In order to solve the above problems, in the magnetic recording and reproducing apparatus of the present invention, a superconducting quantum interferometer (Supe
r Conducting Quntum Interference Device, SQU for short
ID). A superconducting quantum interferometer utilizes a phenomenon in which a superconducting current flowing through a superconducting ring including one or two Josephson junctions changes according to the amount of magnetic flux passing through the ring, and the amount of magnetic flux is highly sensitive. An element to be measured.

Since this superconducting quantum interferometer utilizes a superconducting state, the device has to be made of a superconducting material, and the whole device has to be cooled to a very low temperature so as to be in the superconducting state. However, recent advances in research and development of superconducting materials have been remarkable, and materials that become superconducting at about 95 ° K are being developed. By using such a high-temperature superconducting substance, it becomes possible to reproduce a signal with ultra-high sensitivity using a superconducting quantum interferometer.

(Operation)

The magnetic recording device according to the present invention includes at least a coil for converting a reproduction signal into a magnetic flux and a superconducting ring which forms a superconducting quantum interferometer interlinking with the coil. In order to efficiently transmit the magnetic flux from the coil to the superconducting ring, it is effective to interpose a magnetic path made of a magnetic material. Further, by employing a configuration having a cooling element utilizing the Peltier effect, it is effective in efficiently cooling a necessary portion and maintaining a superconducting state.

The superconducting quantum interferometer used in the present invention includes a DC type including two Josephson junctions and an AC type including one Josephson junction. The direct current type needs to form two Josephson junctions, which is disadvantageous in process as compared with the alternating current type including one Josephson junction, but has an advantage that the circuit configuration is simple. On the other hand, the AC type only needs to form one Josephson junction, which is advantageous in the process, but has a complicated circuit configuration. Any type can be used for the magnetic recording / reproducing apparatus of the present invention, and each advantage can be selected and used.

The superconducting quantum interferometer used in the magnetic recording / reproducing apparatus of the present invention has a very high sensitivity to an external magnetic flux, and therefore has a problem that it is weak to noise such as a leakage magnetic flux other than an external signal and electromagnetic waves. have. In order to solve this problem, in the magnetic recording and reproducing apparatus of the present invention, it is desirable to provide a shield around the superconducting quantum interferometer.
As the shield material, a high magnetic permeability material such as a conventional Ni-Fe alloy (permalloy) or an amorphous alloy can be used. Since a magnetic flux does not penetrate into a superconducting material, it is most preferable to use a superconducting material as a shielding material.

Further, in the magnetic recording apparatus of the present invention, a bias coil disposed so as to link the magnetic flux with the superconducting quantum interferometer element is provided, and an AC bias current is supplied to the bias coil, thereby making it easier to detect a signal. It is possible.

As the superconducting material used in the magnetic recording device of the present invention,
For example, it is possible to use a material having a phase shift such as (Sr _x La _{1 -x} ) ₂ CuO ₄ (x = 0.05 to 0.1) or (Ba _{1 -x} Y _x ) ₃ Cu ₂ O ₇ ( _{x to} 0.3). I can do it. In particular, the latter is a preferable material because it becomes a superconductive state at a high temperature of 95 ° K.

In the magnetic recording / reproducing apparatus of the present invention, the superconducting quantum flux interferometer can detect weak signals and signals from the magnetic head with extremely high sensitivity by being inserted between the magnetic head and the signal detection circuit. Among magnetic recording / reproducing devices, VTRs and other devices have a head mounted on a high-speed rotating silling for recording / reproducing, and signal transmission components such as a rotary transformer are inserted between the head and the recording / detection circuit. I have. In the magnetic recording / reproducing apparatus of the present invention, by constituting this rotary transformer with the above-described superconducting quantum flux interferometer, the reproducing sensitivity can be greatly improved.

The magnetic recording / reproducing apparatus of the present invention is not limited to a VTR,
Audio tape recorders, rigid disk drives,
The present invention is applicable to a magnetic recording / reproducing apparatus including a recording medium and a magnetic head, such as a floppy disk device and a magnetic tape storage device for a computer.

〔Example〕

Next, the magnetic recording / reproducing apparatus of the present invention will be described in detail with reference to examples.

FIG. 1 shows an example of a DC superconducting quantum interferometer used in the magnetic recording apparatus of the present invention. A superconducting ring 12 is constituted by a superconducting material 10 and two Josephson junctions 11, and a magnetic ring 13 such as ferrite is installed so as to penetrate the superconducting ring. Wind the difference wire 14 that transmits the signal. A signal detection line 15 is provided on the superconducting ring. With such a configuration, a weak signal from the magnetic head is transmitted to the magnetic ring 13.
The current that is converted into a magnetic flux that flows through the signal detection line 15 is modulated by the amount of magnetic flux that flows through the magnetic ring 13. Since the current flowing through the superconducting ring is sensitively modulated even with an extremely weak magnetic flux amount penetrating the superconducting ring, by using the superconducting quantum interferometer as in the present invention, the weak current from the head is reduced. Signals can be detected with extremely high sensitivity.

FIG. 2 shows another example of the DC superconducting quantum interferometer used in the magnetic recording / reproducing apparatus of the present invention.
(A) is a plan view, and (B) is a sectional view taken along line A and A 'of (A). A superconducting ring 12, made of a superconducting material as in FIG.
Reference numeral 16 formed by the Josephson junction 11, the magnetic ring 13, the difference line 14, and the signal detection line 15 is an insulating material. In this embodiment, the above-described superconducting quantum interferometer is formed on the substrate 17. By incorporating a cooling element using the Peltier effect or the like in the substrate portion, the portion using the superconducting material is efficiently cooled. It becomes possible.

FIG. 3 shows another example of a DC superconducting quantum interferometer used in the magnetic recording / reproducing apparatus of the present invention. (A) is a plan view, and (B) is a sectional view taken along the line AA 'of (A). This embodiment is an example in which the above-mentioned magnetic ring 13 is not provided, and the difference line 14 for transmitting a signal from the magnetic head and the superconducting ring 12 are directly coupled. Since the superconducting quantum interferometer has extremely high sensitivity to magnetic flux, it can be configured as in this embodiment. Further, as shown in (b), by providing the magnetic shield 18 as if covering the superconducting ring, it is possible to prevent noise generated from external leakage magnetic flux or radio waves. As the magnetic shielding material, a conventional high magnetic permeability material can be used, but it is desirable to use a superconducting material in order to enhance the shielding effect. Insulating materials 16 and 19 are provided to insulate these shielding materials from the superconducting ring and the difference wire.
In FIG. 3A, the magnetic shield shown in FIG.
18, the insulating material 16 is omitted.

FIG. 4 is an example of an AC superconducting quantum flux interferometer used in the magnetic recording apparatus of the present invention. (A) is a plan view,
(B) is a sectional view taken along the line AA 'of (a). In this embodiment, a superconducting ring 12 including one Josephson junction 11, a magnetic ring 13, a difference line 14, and a high-frequency coil 20 for detecting a signal are provided. Also, as shown in FIG. 3, the magnetic shield 18 is configured to cover the superconducting ring. In FIG. 4 (a), the magnetic shield 18 and the insulating material 19 shown in (b) are omitted.

The difference line 14 and the high-frequency coil 20 shown in FIGS.
Has shown the case of one turn, but it is of course possible to make many turns.

Fig. 5 shows an example in which a head is mounted on a rotating cylinder and a signal is recorded and reproduced on a tape, such as a VTR, using a superconducting quantum interferometer as a rotary transformer used for signal transmission. It is. (A) is a cross-sectional view on the center of the rotation axis of the cylinder.
FIG. 4 shows a plan view of the plane B ′. In the present embodiment, the portion that rotates together with the cylinder rotation shaft 21 is
3 'and a winding 14 for transmitting a signal from the magnetic head, and a portion fixed to the stator 22 is a rotating magnetic ring 13 ".
And a superconducting ring 12 including one or two Josephson junctions 11, and a rotating part and a fixed part are combined to form a superconducting quantum interferometer. In the embodiment, a plurality of signals can be transmitted and detected by installing a plurality of the superconducting quantum interferometers in the rotation axis direction. Magnetic shield 18 to magnetically separate each superconducting quantum interferometer
Is preferably provided between the superconducting quantum interferometers. When the difference line 23 is provided on the stator side and the Josephson junction constitutes two DC superconducting quantum flux interferometers, the bias coil is used, and the Josephson junction is one AC superconducting quantum flux interferometer. When a magnetic flux interferometer is configured, it can be used as a high-frequency coil for signal detection. At the time of signal reproduction, a magnetic flux is induced in the rotating magnetic ring 13 ′ by a signal current flowing through the difference line 14,
This magnetic flux passes through the minute air gap 24 and the fixed magnetic ring 13 ″
Is transmitted to Since this magnetic flux penetrates the superconducting ring 12, in the case of DC type, the signal detection line connected to the superconducting ring
15 and by the high frequency coil 23 in the case of the AC type. When recording the signal, the difference line 23
The recording signal can be transmitted to the difference line 14 on the magnetic head side in the same manner as a normal rotary transformer by supplying a recording current to the magnetic head.

FIG. 5 shows another example using a superconducting quantum flux interferometer instead of a rotary transformer. As shown in FIG. 5, a difference line 14 on the head side rotating with the cylinder rotating shaft 21, a rotating magnetic ring 13 ′, a superconducting ring 12 and a fixed magnetic ring 13 ″ fixed to the stator 22, The magnetic shield 18 constituted by the wire 23 is fixedly installed on either the rotating side or the fixed side.

In the example shown in FIG. 5, the axial flow increases with the number of channels, whereas in the example shown in FIG. 6, the diameter needs to be increased in order to increase the number of channels. Either example can be used depending on the device used. 5 and 6, the cooling element using the Peltier effect or the like is incorporated in the portion of the stator 22.
It is possible to efficiently cool portions of the superconducting material.

〔The invention's effect〕

As described above, in a magnetic recording device, by using a superconducting quantum flux interferometer in a portion for detecting a signal from a magnetic head, a weak reproduced signal can be detected with extremely high sensitivity, and a high-density signal can be detected. Magnetic recording becomes possible. In particular, in a device in which a head is mounted on a rotating cylinder such as a VTR, a highly sensitive signal can be reproduced by using a superconducting quantum flux interferometer instead of a rotary transformer.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of a superconducting quantum flux interferometer used in the magnetic recording apparatus of the present invention, and FIGS. 2 to 4 are implementations of the superconducting quantum flux interferometer used in the magnetic recording apparatus of the present invention. FIGS. 5 and 6 show an embodiment of a superconducting quantum flux interferometer used in place of a rotary transformer. 10: Superconducting material 11: Josephson junction 12: Superconducting ring 13: Magnetic ring 14: Difference line 15: Signal detection line 17: Substrate 18: Magnetic shield 20: High frequency coil 21 …… Cylinder rotating shaft 22 …… Stator

Continued on the front page (72) Inventor Takeo Yamashita 1-280 Higashi-Koigabo, Kokubunji-shi, Hitachi, Ltd. Central Research Laboratory Co., Ltd. References JP-A-59-178601 (JP, A) JP-A-61-280584 (JP, A) JP-A-63-259817 (JP, A)

Claims (5)

(57) [Claims] 1. A rotor having a magnetic head, a stator to which at least a part of a rotation shaft of the rotor is fitted, and opposed to each other with a gap between the rotor and the stator. And a magnetic ring on the rotor side, a differential wire for transmitting a signal from the magnetic head is wound on the magnetic ring on the rotor side, and a magnetic wire on the stator side is connected to the differential wire on the magnetic ring on the stator side. A magnetic recording / reproducing apparatus, wherein grooves are formed facing each other and a superconducting ring including a Josephson junction is embedded in the grooves. A plurality of magnetic rings opposed to each other with a gap provided between each of the rotor and the stator;
A superconducting ring including a Josephson junction is formed in each of the magnetic rings on the rotor side, and the groove is formed in each of the magnetic rings on the stator side. The magnetic recording / reproducing apparatus according to claim 1, wherein the magnetic recording / reproducing apparatus is embedded. 3. The magnetic ring according to claim 1, wherein the magnetic ring on the stator side is provided with a difference line magnetically coupled to the superconducting ring. The magnetic recording and reproducing apparatus according to claim 1. 4. The apparatus according to claim 1, wherein a magnetic shield is provided on a side of said magnetic ring.
Item 7. A magnetic recording / reproducing apparatus according to any one of the above items. 5. A magnetic recording / reproducing apparatus according to claim 1, wherein a cooling element is incorporated in said stator.