JPS5987605A - Magnetic reproducer - Google Patents

Abstract

PURPOSE:To obtain a reproduction head which can work with high sensitivity even with a small track width by having a reproduction head which contains a magnetic recording medium and constitutes a high frequency resonance circuit and at the same time providing a magnetic material having its high frequency characteristics varied by a signal magnetic field given from the recording medium. CONSTITUTION:A magnetic layer 4 having 200-2,000Angstrom thickness made of YIG, etc. and having its high frequency characteristics and high frequency loss varied by a signal magnetic field is formed to a recording layer 3. A reproduction head 5 is constituted so that a high frequency resonance circuit having its resonance current path set in the thickness direction of a recording medium 1 is constituted with an external conductor 6, a needle-shaped electrode 7 and a conductor 11. When a signal is reproduced, the head 5 is driven to inject the high frequency energy of a microwave band to the high frequency resonance circuit from a high frequency oscillator 14. In this case, the magnetic resonance of a magnetic material which is produced by a relation between a frequency of high frequency energy and a magnetic field is applied to make it possible to make use of a change of the magnetic material having large high frequency characteristics. Thus the high frequency voltage obtained from said resonance circuit receives modulation. Then this change of the high frequency voltage is detected by a peak wave detecting circuit 18 to obtain a reproduction output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic reproducing device that reproduces signals by utilizing changes in the high frequency characteristics of a magnetic material due to a signal magnetic field from a magnetic recording medium.

[Technical background of the invention and its problems]

Magnetic recording and reproducing systems are currently widely used in VTRs, various disk memories, and tape memories, but as the amount of information increases and devices become smaller, there is a demand for further improvements in recording density. . However, since the conventional apparatus uses a magnetic flux sensitive head such as a ring head for reproduction, when the track width is narrowed to increase the recording density, the reproduction output level decreases, making reproduction with a good S/N ratio difficult.

Therefore, the inventors have already proposed a method for reproducing signals using changes in the high frequency characteristics of a magnetic material due to a magnetic field (signal magnetic field) based on a recorded signal from a magnetic recording medium, as a method for more sensitive reproduction. are doing. That is, a chip of a magnetic material such as permalloy whose magnetic permeability and high frequency loss change with changes in the magnetic field is placed facing the surface of the magnetic recording medium, and this magnetic chip is used as an element of a high frequency resonant circuit. Inject high frequency energy into the In this case, when the characteristics of the magnetic material change due to changes in the signal magnetic field,
Since the resonant frequency and Q of the high frequency resonant circuit change, the high frequency voltage appearing at the output of this resonant circuit also changes accordingly. Therefore, by detecting this change in high frequency voltage via a detection circuit, a signal reproduction output can be obtained.

In this method, the reproduction output level depends only on the high-frequency energy injected into the resonant circuit from a high-frequency oscillator, etc., and does not depend on the track as in conventional magnetic flux-sensitive heads. It is possible to obtain a high level, high S/N reproduction output even with an extremely narrow track width.

However, with the above configuration, the dimension in the track width direction (width dimension) of the magnetic chip is as small as the track width, and the dimension in the direction perpendicular to the magnetic recording medium surface (thickness dimension) is also as small as the track width. You have to use something extremely small. The width dimension of the magnetic chip is limited to prevent crosstalk from adjacent tracks.

In addition, the limitation on the thickness dimension is that if it is too large, the signal magnetic field concentrated near the surface of the recording medium will reach only a small part of the magnetic chip, making it impossible to sufficiently change the characteristics of the magnetic chip, resulting in reproduction sensitivity. This is because it decreases. This tendency becomes more pronounced as the recording wavelength becomes shorter, so if the thickness of the magnetic material is large, the reproduction frequency characteristics (bandwidth) will deteriorate.

For this reason, magnetic chips need to have extremely fine shapes, which not only makes processing difficult, but also causes wear due to contact with the recording medium, which shortens their lifespan significantly. There were 0 problems [Objective of the Invention] The object of the invention is to be able to reproduce signals magnetically recorded with an extremely narrow track width with high sensitivity, to easily manufacture a reproducing head, and to extend the life of the reproducing head. The purpose of the present invention is to provide a magnetic reproducing device that can perform the following functions.

[Summary of the invention]

The present invention configures a reproducing head that includes a magnetic recording medium to form a high-frequency resonant circuit, and provides high-frequency characteristics that are applied to a signal magnetic field from the recording medium on at least one of the recording medium and the recording medium abutting portion of the reproducing head. A magnetic material that changes is provided, and high frequency energy is injected into the high frequency resonant circuit, and a change in the high frequency voltage appearing in the output is detected to reproduce the signal recorded on the recording medium. [Effects of the Invention] According to the present invention, since the high frequency resonance circuit of the T1 raw head is formed including the magnetic recording medium, the reproduction head can be manufactured easily and its lifespan can be extended. be able to.

That is, since the reproducing head can be constructed so that a resonant current flows through the recording medium, it may be mainly composed of, for example, needle-shaped electrodes. The magnetic material is provided on the recording medium or at the tip of the needle-like electrode, both of which are technically easy.

For example, the former can be easily formed to a desired thickness using a film forming technique such as sputtering. In the latter case, for example, a magnetic film is deposited on the side surface of the acicular substrate, and a conductive film is deposited on the part of the magnetic film except for the tip of the magnetic film to reduce changes in the high frequency characteristics of this part. By doing this, the same results as using a minute magnetic chip can be obtained. In this case, since the magnetic film is formed on the side surface of the acicular substrate perpendicular to the surface of the recording medium, there is an advantage that it can be used for a long period of time even if it wears out.

[Embodiments of the invention]

FIG. 1 shows the configuration of a magnetic reproducing apparatus according to an embodiment of the present invention. In the figure, a magnetic recording medium 1 has barium ferrite or cobalt film (C) on a base layer 2.
In this example, a recording layer 3 is formed on the recording layer 3.
Yttrium garnet (YIG) or permalloy (Ni
-Fe), etc., with a thickness of approximately 2001 to 2000X.
In the case of YIG, it can be formed by rubbing YIG powder, and in the case of permalloy, it can be formed by sputtering.On the other hand, the reproducing head 5 has a needle-like electrode 7 provided as an inner conductor inside a cylindrical outer conductor 6. It is mainly composed of coaxial resonators. Here, the needle-like electrode 7 has a tungsten film 9 of 0.1% on one side of the needle-like base 8 made of glass or the like in this example.
A conductive film 10. is formed to a thickness of about μ to 0.3 μ on the surface of the portion of the tungsten film 9 other than the tip portion 9a to reduce high frequency loss in this portion. For example, a copper film is entirely formed, and its tip is connected to the lower end opening 6 of the outer conductor 6.
A conductor II that protrudes from a and is in contact with the recording medium 1 is provided on the back side of the recording medium I, facing the outer conductor 6 and the needle-like electrode 1, and is further provided on the outside A permanent magnet I2 (an electromagnet may be used) for generating a bias DC magnetic field is arranged as necessary. In this way, the reproducing head 5 is constructed so that the outer conductor 6, the needle-like electrode 7, and the conductor 11 form a high-frequency resonant circuit with the resonant current path in the thickness direction of the recording medium 1. 0 To reproduce the signal recorded on the recording medium 1, the reproducing head 5 is moved relative to the recording medium 1 as shown by the arrow 13.0 Then, a high frequency oscillator 14 is connected to the high frequency resonance u path, that is, the coaxial resonator. For example, from 500MHz to 1001
High frequency energy in the microwave band of about 000O is injected. In this case, the signal magnetic field from the recording medium 1 changes the high frequency characteristics of the magnetic layer 4, such as high frequency loss and magnetic permeability, but in particular, the magnetic resonance of the magnetic material caused by the relationship between the frequency of the applied high frequency energy and the magnetic field is applied. Especially Eli,
This large change in the high frequency characteristics of the magnetic material can be utilized. As a result, the high frequency voltage obtained from the high frequency resonant circuit is modulated. Therefore, the change in this high frequency voltage can be controlled by, for example, the diode 15, the resistor 16, and the capacitor fl.
By detecting with the peak detection circuit 18 consisting of
Signal regeneration output can be obtained.

According to this embodiment, the level of the signal reproduction output 19 depends on the power energy of the oscillator 14, and even if the track width is narrow, a signal reproduction output with a sufficient level and a good S/N ratio can be obtained.

In addition, by reducing the film thickness 'k, J- of the tungsten film 9, it is possible to reproduce signals recorded at high density in the track length direction, such as in perpendicular magnetization recording, with high sensitivity. Because of these factors, it becomes possible to perform ultra-high density recording and reproduction, which was previously impossible.

Furthermore, since the magnetic film 4 is formed on the surface of the recording medium 1, it can be easily formed thinly and the signal magnetic field can be detected with high sensitivity. Further, an oil film layer is provided on the surface of the magnetic film 4, and the electrode 7 and the magnetic film 4 are coupled by the capacitance therebetween.

Next, some other embodiments of this invention will be described.

In the embodiment shown in FIG. 2, an ordinary recording medium 1 without a magnetic film 4 (FIG. 1) whose high frequency characteristics change depending on the signal magnetic field is used, and instead of the magnetic film 4 (FIG. 1), the acicular substrate 8 of the acicular electrode 7 is used. This is formed in place of a similar magnetic MN20'fc tungsten film 9 on the side surface of the magnetic film 20, and a conductive film 10 is also formed on the surface of the portion other than the tip 20a of this magnetic film 20 to reduce high frequency loss. are doing. In this embodiment, the signal magnetic field from the recording medium 1 changes the high frequency characteristics mainly of the tip 20a of the magnetic film 20, which changes the high frequency voltage appearing at the output of the high frequency resonant circuit. By detecting changes in the high frequency voltage, a signal reproduction output can be obtained from the portable circuit IIF.

Note 1. The needle-shaped electrode 7 in FIG. 2 may have a structure in which a magnetic film 20 is sandwiched between conductive films 10a and 10b, as shown in FIG.

FIGS. 4 and 5 show examples in which the needle electrode 7 is also used as the main pole of a perpendicularly magnetized head. That is, in FIG. 4, an excitation coil 2 is mounted on a magnetic pushpiece 21 on the back side of the recording medium 1, facing the needle electrode 7 having the same structure as in FIG.
A sub-pole excitation type perpendicular magnetization head, in which a sub-magnetic pole 23 formed by winding 2 is disposed, and a magnetic film 20f of a needle-shaped electrode 7, particularly a magnetic material such as permalloy, is used as a main pole.

In this case, by supplying the recording signal current 24 to the excitation coil 22, the recording layer 3 of the recording medium 1 can be magnetized in the perpendicular direction (thickness direction) to perform high-density recording.

It is also possible to use the perpendicular magnetization head as an erasing head by flowing an AC or DC erasing current instead of the recording signal current.

On the other hand, in FIG. 5, in order to use the acicular electrode 7 as a main pole excitation type perpendicular magnetization head, a magnetic material film 2 such as permalloy is used.
A ferrite film 25 is formed on top of the magnetic material film 20 so that the tip portion 20h that contributes to reproduction of the magnetic film 20 is exposed, and then an excitation coil 26 is wound around the excitation coil 26. I try to let it flow.

In this case, it is possible to magnetically shield the portion of the needle electrode 7 other than the tip 20& of the magnetic film 2o with a copper film 27 or the like to prevent the influence of unnecessary high frequency loss of the needle electrode 7 during reproduction. desirable.

As described above, according to the present invention, a part of the reproducing head can also be used as a perpendicular magnetization type recording head or erasing head.

Next, in the embodiment shown in FIG. 6, a coil 28 is wound around the reproducing electrode 7, preferably near the tip, and an auxiliary resonant circuit 30 is formed by this coil 28 and a capacitor 29 connected, for example, in parallel. By causing this sub-resonant circuit 30 to oscillate and resonate with the high-frequency energy from the device 14, the reproduction sensitivity is completely improved. In other words, in this embodiment, the sub-resonant circuit 30 is supplied with high-frequency energy. The high-frequency magnetic field generated by this is strongly applied to the magnetic film 20 together with the signal magnetic field from the recording medium 1, which causes a large change in high-frequency loss due to magnetic resonance absorption of the magnetic film 20, and the signal reproduction output increases accordingly. 19 also increases. According to experiments conducted by the inventors, it has been confirmed that the signal reproduction output tl is improved by 10 times compared to the case where the sub-resonant circuit 30 is not provided.

This invention can be implemented with various other modifications. For example, in each of the above embodiments, a magnetic material whose high frequency characteristics change depending on the signal magnetic field is formed on the recording medium 1 in FIG.
In FIGS. 6 to 6, it is formed on the needle-like substrate 7 side, but it may be formed on both sides.

Further, in the embodiment, the conductor 11 is arranged on the back side of the recording medium 1, but instead, by including a conductive material in the recording medium 1 or by providing a conductor layer overlapping with the recording layer 3, it is possible to create a recording island. The body I may be made electrically conductive. When the recording medium 1 has conductivity in this way, in order to avoid electrical contact with the needle-like electrode 7, an insulating layer or an oil film layer is applied to the surface, and this insulating layer is used as an interlayer electric shield. It is also possible to form a capacitance and include this capacitance in the high frequency resonant circuit.

Furthermore, the magnetic reproducing device according to the present invention can be applied not only to perpendicular magnetization recording but also to normal longitudinal recording.

[Brief explanation of the drawing]

1 to 6 are diagrams showing the configuration of a magnetic reproducing device according to an embodiment of the present invention, respectively. I... Magnetic recording medium, 2... Pace layer, 3... Recording layer, 4, 20... Magnetic layer whose high frequency characteristics change depending on the signal magnetic field, 5... Reproduction head, 6... - Outer conductor of coaxial resonator, 7... Needle electrode, 8... Needle base, 9
°°"Tungsten film, 10-... conductive film, 11...
Conductor (ground plate), 12... Permanent magnet, 14... High frequency oscillator, 18... Peak detection circuit, 19... Signal regeneration output collar 23... Sub magnetic pole, 24... Recording signal Current, 25... Ferrite film, 26... Excitation coil,
22...Copper film, 28...Coil, 29...
Capacitor, 30... Sub-resonant circuit. Figure 4 6 Figure 5 Figure 6 (Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of the case Patent Li857-196377 2, Name of the invention Magnetic reproducing device 3, Person making the amendment Relationship to the case Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. 5, Voluntary amendment 6, Specification subject to amendment (1) 1 Cobalt film” on page 8, line 18 of the specification is corrected to “cobalt chrome.” (2) Same No. ``Tungsten film'' on page 9 @ line 14 is written as ``permalloy film.''"Tungstenfilm" in the 12th ladle of page 11 is referred to as "permalloy film". (5) "Tungsten film" in line 9 of page 12 is referred to as "permalloy film".
"Permalloy membrane" and pulled up. (6) On page 15 of the same fA, lines 13 to 14, [The frequency characteristics change due to defeat. ” to join. (7) "Tungsten film" on page 16, line 16 is corrected to "permalloy film".

Claims (1)

Scope of Claims: (1) An apparatus for reproducing signals recorded on a magnetic recording medium by utilizing changes in high frequency characteristics of a magnetic material due to a signal magnetic field from a magnetic recording medium, including a high frequency In addition to configuring the reproducing head that forms a resonant circuit,
A magnetic material is provided on at least one of the recording medium and a portion of the reproducing head that is still in contact with the recording medium, high frequency energy is injected into the high frequency resonant circuit, and a change in high frequency voltage appearing in the output is detected. A magnetic reproducing device characterized in that it reproduces signals recorded on a recording medium. (2) A patent claim characterized in that the reproducing head includes a needle-like electrode whose tip comes into contact with the recording medium, and a conductor disposed on the back side of the recording medium to face the needle-like electrode. The magnetic reproducing device according to item 1. (3) The magnetic head according to claim 1, wherein the reproducing head includes a needle-shaped electrode whose tip is brought into contact with the recording medium, and the recording medium is electrically conductive. Reproducing device 0 (4) The needle-like electrode has a magnetic film whose high frequency characteristics change depending on the signal magnetic field applied to the side surface of the needle-like base, and a conductive film on the surface of the magnetic film except for the tip. The second claim characterized in that
3. The magnetic reproducing device according to item 3 or 3. (5) Fully couple the sub-resonant circuit to the needle-like electrode, make this sub-resonant circuit resonate with the injected high-frequency energy, and change the high-frequency characteristics of the high-frequency magnetic field generated by the resonant current flowing through the sub-resonant circuit depending on the signal magnetic field. Claims 2 to 3 are characterized in that the magnetic material is added to the magnetic material
Magnetic reproducing device 0 according to any one of Clauses 4 (6) Claims characterized in that the sub-resonant circuit includes a coil wound around a needle-like electrode and a capacitor connected to the coil. 6. The magnetic reproducing device according to item 5. (7) The recording medium has an insulating layer on the surface,
2. The magnetic reproducing device according to claim 1, wherein the high frequency resonant circuit includes a capacitance formed by the insulating layer. (8) The acicular electrode is also used as a main pole constituting a sub-pole excitation type perpendicular magnetization head together with a sub-pole having an excitation coil provided on the back side of the recording medium opposite thereto. Claims 2 to 6 of the claims
2. The magnetic reproducing device according to any one of paragraphs. (9) The sword-shaped electrode is also used as the main pole of a main pole excitation type perpendicular magnetization head by being wound with an excitation coil. The magnetic reproducing device according to any one of the above.