JPH0196812A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To optimize a gap width at the time of recording and reproducing and to improve the S/N of a device by providing a means to form the gap part of the head core of a recording and reproducing device with the gap forming member of a double layer or above and change a magnetic head, in which one layer is composed of a superconductor, and the gap forming member of the superconductor to a normal conducting condition. CONSTITUTION:A magnetic head 1 is composed by bonding head cores 2 and 3 and a gap part 1a a little separated to the tip part of both cores 2 and 3 is formed. To the gap part 1a, a gap forming member 6 composed of two layers of a glass 4 of a nonmagnetic material and a superconductor 5 is filled. The conductor 5 is included in the core 3, a terminal part 5a protruded on the surface of the core 3 is connected to a critical current generating device 8, and the conductor 5 is changed to a superconducting condition and a non-conducting condition by the control of the generating device 8. The recording current is supplied to a coil 7 wound to one edge of the core 3 and at the time of recording and reproducing, the gap width of the head 1 is optimumly designed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a recording and reproducing apparatus that records and reproduces signals on a magnetic recording medium using a magnetic head.

2. Description of the Related Art A VTR is a typical product that records signals on a magnetic recording medium. In order to record long programs on a VTR, it is necessary to shorten the recording wavelength as much as possible.The shortest recording wavelength is determined by the gap width of the playback head, so the gap width of the playback head is currently as narrow as 0.3 μm. Currently, most VTRs share a recording head and a reproducing head, so the gap width of the magnetic head is generally determined from the shortest recording wavelength as described above.

Problems to be Solved by the Invention If this happens, recording will be performed using a magnetic head with a narrow gap width. During recording, it is desirable to increase the residual magnetization of the magnetic layer as much as possible.In other words, it is necessary to increase the volume of residual magnetization.The volume is the product of the track width, wavelength, and magnetization depth. The magnetization depth becomes shallower as the gap width becomes narrower, so when it comes to recording, it is said that the gap width of the magnetic head should be wider than the gap width of the read head, which is determined by the shortest recording wavelength. It is most efficient to configure the recording head and the reproducing head independently, but for home use, a dual-purpose head must be used at least from the cost standpoint.

Therefore, the purpose of the present invention is to use a dual-purpose head, but switch between a wide gap width during recording and a narrow gap width during playback, and perform recording and playback under optimal conditions for each. The present invention provides a recording/playback device.

Means for Solving the Problems The present invention provides a magnetic head in which the gap portion of the head core is formed of two or more layers of gap forming members, at least one of which is made of a superconductor, and a gap forming member made of the superconductor. This is a recording/reproducing device having means for changing to a normal conductor state.

Operation When a superconductor gap forming member configured in the gap portion of a magnetic head is recorded in a superconducting state, due to the Meissner effect, no magnetic field passes through the superconductor gap forming member, and the actual gap width of the magnetic head becomes the same as that of the superconductor gap forming member. During regeneration, the superconductor becomes a normal conductor, the Meissner effect disappears, and the actual gap width becomes narrow.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

- Figure 2 is a plan view of the magnetic head, and Figure 1 is Figure 2A.
FIG. 3 is a partially enlarged view of the gap portion seen from the direction. The magnetic head 1 is constructed by bonding a helad core (a) 2 and a head core (b) 3. A gap portion 1a is formed at the tips of these two herad cores with a slight distance between them, and the gap portion 1a is filled with a gap forming member 6 made of two layers of non-magnetic glass 4 and superconductor 5. . The superconductor 5 is contained in the head core (b) 3, and the terminal portion 5a further protrudes from the surface of the head core (b) 3. A critical current generator 8 is connected to the terminal portion 5a, and under the control thereof, the superconductor 5 is changed into a superconductor state and a normal conductor state. Further, a coil 7 for passing a recording current is wound around one end of the head core (b) 3, and the current necessary for recording is supplied to the head cores (a) 2 and (b) 3.

Next, we will explain the case where this magnetic head is used in a recording/reproducing device that arranges a plurality of magnetic heads on a guide drum, winds a magnetic tape at a predetermined angle, and rotates the guide drum at high speed to record and reproduce video signals. do. In the recording mode, a predetermined recording current is supplied to the coil 7, and the recording current generates a magnetic field in the head cores (a) 2 and (b> 3).Most of the magnetic field is generated by a closed loop magnetic field in the head core 2.3 as shown by arrow C. However, the gap portion 1a at the tip of the head core
In this case, a leakage flux of d occurs. Recording is performed by magnetizing the magnetic tape in contact with the gap portion 1a by this leakage magnetic flux. In this recording mode, the critical current generator 8 does not operate and the superconductor 5 maintains its superconducting state.
Due to the Meissner effect (complete demagnetization effect in which no external magnetic field enters the superconductor) unique to superconductors, no magnetic field is generated in the superconductor 5 even when a recording current is passed through the coil 4. As a result, the gap forming member has a two-layer structure of the superconductor 5 and the glass 4, and the gap width becomes the dimension a shown in FIG. Therefore, the leakage magnetic flux d is generated far from the front surface of the head tip, and as a result, residual magnetic flux is formed deep in the thickness direction of the magnetic tape, and the residual magnetization volume becomes thick.

In the regeneration mode, the superconductor 5 is now transferred from the critical current generator 8.
A current that exceeds the critical current density of the material is applied to the terminal portion 5.
a to change the superconductor 5 from a superconducting state to a normal conducting state. Therefore, the superconductor 5 of the gap forming member 6
Since the magnetic field passes through the inside of the gap, the gap width becomes the dimension b in FIG.

Therefore, the signals recorded on the magnetic tape are read with a narrower gap than during recording. Then, the leakage magnetic flux generated from the magnetic tape forms a magnetic path in the Herad core 2.3,
A current is induced in the coil 7 to obtain a reproduction signal.

The critical current can be easily supplied from the outside to the magnetic head 1 on the rotating head drum by a current supply means such as a rotary transformer or a slip ring brush. Even if multiple magnetic heads are placed on a rotating head drum,
Since one current supply means can supply current to all the magnetic heads, the number of required channels of the rotary transformer does not depend on the number of magnetic heads.

Note that the following may be used as the superconducting material.

5r-Ba-YCLJO308-δ (room temperature) Y-Ba-
Cu-0 (near 90) Er-Ba-Cu-0 (thin film) Effects of the invention According to the present invention, during reproduction, the gap width is determined from the shortest recording wavelength, and during recording, the gap width is wider than that gap width. Therefore, the gap width of the magnetic head, which conventionally was uniquely determined by the specifications of the read head, can be designed as the optimal gap width for playback and recording.As a result, During recording, the maximum amount of residual magnetic flux can be achieved with the same recording current, resulting in a large amount of magnetic flux leaking from the magnetic tape.Then, during playback, the magnetic flux flowing through the magnetic head also increases, and the voltage induced in the coil becomes high. /N good signal can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a front view of the magnetic helad gap, and FIG. 2 is a plan view of the magnetic head. 1... Magnetic head, 2... Head core (a), 3.
...Head core (b), 5...Superconductor, 8...Critical current generator.

Claims (1)

[Claims] A recording head comprising a magnetic head in which a gap portion of a head core is formed of two or more layers of gap forming members, at least one layer of which is made of a superconductor, and a means for changing the gap forming member of the superconductor to a normal conductor state. playback device.