JPS60151804A - Reproducing system of magnetic recording signal - Google Patents

Abstract

PURPOSE:To reproduce magnetic recording signals of an extra-high density with good frequency characteristics by not impressing directly a signal magnetic field to a magnetic field detecting element but converting the signal magnetic field temporarily to an electromotive force with a conventional ring magnetic head or the like and converting a current based on this electromotive force to a magnetic field and impressing this magnetic field to the magnetic field detecting element to detect the signal magnetic field including a magnetic field based on high frequency components with a high sensitivity. CONSTITUTION:When a magnetic field is impressed to a magnetic material 15 from a coil 14, the high frequency characteristic of the magnetic material 15, the permeability of the magnetic material 15, or the magnetic resonance state of the magnetic material 15 to a high frequency energy from a high frequency oscillator 18 is changed in accordance with variation of this magnetic field. Then, a high frequency voltage, namely, a resonance output voltage which appears in the output of a resonance circuit consisting of the magnetic material 15 and a resonance capacity 17 is changed. This resonance output voltage is detected by a peak detecting circuit 23 consisting of a diode 20, a capacitor 21, and a resistance 22 or the like to obtain a voltage output changing in accordance with variation of the high frequency characteristic of the magnetic material, namely, a reproduced output corresponding to signals recorded on a magnetic recording medium 11.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a magnetic recording signal reproducing method for reproducing signals recorded at high density on a magnetic recording medium with high sensitivity [Technical background of the invention and its problems] Magnetism The recording method is currently widely used in VTRs, audio tape recorders, various disk memories, tape memories, etc., but as the amount of information increases and devices become smaller, further improvements in recording density are required. It has become. However, since conventional devices use a magnetic flux-sensitive head, typically a ring-type magnetic head, for reproduction, narrowing the track width to increase recording density lowers the reproduction output level, making it difficult to reproduce with good S/N ratio. The problem was that it was difficult.

Therefore, the inventors proposed a high-sensitivity reproduction method that reproduces magnetically recorded signals by utilizing changes in the high-frequency characteristics of a magnetic material caused by a magnetic field (signal magnetic field) based on recorded signals from a magnetic recording medium. There is.

FIG. 1 shows an example of a magnetic recording signal reproducing apparatus using this method. That is, a thin film magnetic material 2, such as a permalloy thin film, whose high frequency characteristics change upon application of a magnetic field, is placed opposite the recording magnetic surface of the magnetic recording medium 1. This magnetic material 2 constitutes a resonant circuit together with a resonant capacitor 4 connected to it via a thin film conductor 3, and high frequency energy in the microwave band is injected into this resonant circuit from a high frequency oscillator 5 via a high frequency coupling capacitor 6. be done. In this case, when a signal magnetic field from the magnetic recording medium 1 is applied to the magnetic body 2, the magnetic body 2 changes in high frequency characteristics in response to changes in the signal magnetic field, such as changes in magnetic permeability or high frequency loss, or from a high frequency oscillator 5. , which causes a change in the magnetic resonance state at the frequency of the radio frequency energy, which changes the resonant output voltage of the resonant circuit. Therefore, by detecting the output voltage of this resonant circuit with a peak detection circuit 10 comprising, for example, a diode 7, a capacitor 8, and a resistor 9, a reproduced output of the signal recorded on the magnetic recording medium 1 can be obtained.

In this method, the reproduction output level depends only on the high-frequency energy injected from the high-frequency oscillator 5 into the resonant circuit, and does not depend on the track width 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, since this reproduction method is a magnetic field detection type,
In particular, it was difficult to achieve high reproduction sensitivity for recorded signals with high frequency components, and there were some difficulties in terms of frequency characteristics. this is,
This is generally caused by the fact that high frequency components of the signal magnetic field from the magnetic recording medium are concentrated near the surface of the medium. That is, as the recording frequency increases, the recording wavelength on the magnetic recording medium becomes shorter, and accordingly, the strength of the signal magnetic field decreases exponentially as the distance from the medium surface increases.

Therefore, in order to reproduce high-frequency signals with good sensitivity, the dimensions of the magnetic body 2 in FIG. 1, particularly the dimension d in the thickness direction of the magnetic recording medium 1, must be made sufficiently small, for example, about 5 μm or less. However, processing the magnetic material 2 into such a fine shape is not only technically difficult, but also has the problem of shortening the lifespan due to wear, and also has the problem of increasing the demagnetizing field that is harmful to playback. .

The same problem also applies to a reproduction method using a magnetoresistive element whose electrical resistance changes depending on the magnetic field instead of the magnetic material 2.

[Objective of the Invention] An object of the present invention is to detect the signal magnetic field from a magnetic recording medium as a change in the high frequency characteristics of a magnetic material or a change in the resistance of a magnetoresistive element and to reproduce a magnetic recording signal. Detects magnetic fields based on frequency components with high sensitivity,
The object of the present invention is to provide a magnetic recording signal reproducing method that makes it possible to reproduce ultra-high-density magnetic recording signals with good frequency characteristics. Do not apply directly to the body or magnetic field detection element consisting of a magnetoresistive element.
It is characterized in that it is first converted into an electromotive force using a conventional ring-shaped magnetic head, and then the current based on the electromotive force is converted back into a magnetic field and applied to the magnetic field detection element.

[Effects of the Invention] According to the present invention, the signal magnetic field from the magnetic recording medium is first converted into an electromotive force, and then converted back into a magnetic field and applied to the magnetic field detection element, resulting in a high frequency The component signal magnetic field can also be detected with high sensitivity. That is, conversion from a signal magnetic field to an electromotive force is performed using, for example, a conventional ring-shaped magnetic head.
By reducing the magnetic gap of this head, the signal magnetic field can easily detect magnetic fields with high frequency components concentrated near the surface of the magnetic recording medium. Therefore, highly sensitive reproduction can be performed over a wide frequency band, and the frequency characteristics are significantly improved. Further, according to the present invention, the dimensions of the magnetic body are not required to be particularly minute, unlike those for directly detecting a signal magnetic field, so that the demagnetizing field is small, which also contributes to improving the reproduction sensitivity.

Furthermore, since the magnetic material does not come into direct contact with the magnetic recording medium, the problem of wear is reduced and the service life can be extended.

Furthermore, when a ring-shaped magnetic head is used as a means of converting the signal magnetic field into electromotive force, it can also be used for recording purposes, so despite the remarkable improvement in playback characteristics, the signal magnetic field can be converted into magnetic material or magnetic resistance. This method has the advantage that the configuration is not particularly complicated compared to a method in which detection is performed directly using an element.

Embodiment of the Invention FIG. 2 shows the configuration of a magnetic recording signal reproducing apparatus according to an embodiment of the invention.

In FIG. 2, reference numeral 11 denotes a magnetic recording medium such as a magnetic tape, and a ring-shaped magnetic head 12 is placed such that the tip (magnetic gap) 11a is in contact with the magnetic surface of the magnetic recording medium 11.
is located. A current based on the electromotive force induced by the signal magnetic field from the magnetic recording medium 11 flows through the coil 13 wound around the core of the ring-shaped magnetic head 12 .

This current is supplied to a coil 14 wound around a magnetic material 15, and this coil 14 generates a magnetic field. This magnetic field changes in accordance with the signal recorded on the magnetic recording medium 11, similar to the signal magnetic field from the magnetic recording medium 11, and is applied to the magnetic body 15.

The magnetic material 15 is a thin film magnetic material such as a permalloy thin film or a YIG thin film, and its high frequency characteristics change depending on the magnetic field applied from the coil 14. This magnetic body 15 is connected to a resonant capacitor 17 via a thin film conductor 16, and constitutes a resonant circuit with this resonant capacitor 17. This resonant circuit includes a high frequency oscillator 18 and a high frequency coupling capacitor 19.
High frequency energy of approximately several tens of MHz to 100 MHz or higher is injected through the injector.

When a magnetic field is applied to the magnetic body 15 from the coil 14, the magnetic body 15 causes a change in high frequency characteristics due to a change in the magnetic field, such as a change in permeability or high frequency characteristics, or a change in the high frequency oscillator 18.
It causes a change in the magnetic resonance state in response to high frequency energy from. As a result, the high frequency voltage appearing at the output of the resonant circuit composed of the magnetic body 15 and the resonant capacitor 17, that is, the resonant output voltage changes. Therefore, this resonant output voltage is applied to the diode 20. as in the case of FIG. A voltage output that changes according to changes in the high frequency characteristics of the magnetic material 15, that is, a reproduction output corresponding to the signal recorded on the magnetic recording medium 11, is detected by a peak detection circuit 23 etc. consisting of a capacitor 21 and a resistor 22. can be obtained.

9- In this embodiment, the depth d' of the magnetic gap 12a of the ring-shaped magnetic head 12 corresponds to the dimension d of the magnetic body 2 in the thickness direction of the magnetic recording medium in FIG. Magnetic fields are effectively detected. According to recent magnetic head manufacturing technology, this magnetic gap 12
It is relatively easy to set the depth d' of a to about several micrometers, and it is technically much simpler than setting the dimension d of the magnetic body 2 to about this size.

In this way, the signal magnetic field from the magnetic recording medium 11 is detected by the ring-shaped magnetic head 12 with the same sensitivity for high frequency component magnetic fields as for low frequency component magnetic fields, so the electromotive force corresponding to this signal magnetic field is If the current based on the signal is taken out from the coil 13, converted into a magnetic field again by the coil 14, and applied to the magnetic body 15, high reproduction sensitivity can be obtained over a wide frequency band compared to the case where the signal magnetic field is directly applied to the magnetic body. It is possible to improve the characteristics.

Furthermore, since the ring-shaped magnetic head 12 is mainly composed of a bulk magnetic core, it has extremely less wear and a longer life compared to the case where the WI film 10-magnetic material is in direct contact with the magnetic recording medium 11. It is.

Furthermore, since the magnetic body 15 detects not the signal magnetic field existing near the surface of the magnetic recording medium 11 but the magnetic field converted via the ring-shaped magnetic head 12 and the coils 13 and 14, It does not need to be particularly small in size, as it only needs to be within the range of the generated magnetic field. Therefore, the demagnetizing field is reduced, and the reproduction sensitivity over the entire frequency band can be further increased.

FIG. 3 shows another embodiment of the present invention, which is an example applied to a tensor magnetic permeability (hereinafter referred to as tensor μ) coupling type reproducing device.

Generally, when a pair of coils are arranged orthogonally in a microwave circuit, no coupling occurs between the two coils, but there is a magnetic material in the microwave circuit, and the microwave frequency and applied magnetic field are applied to it. When the relationship causes magnetic resonance, coupling occurs between both coils through the magnetic material.

This connection is called a tensor μ connection. The inventors have already proposed a method for reproducing magnetic recording signals that utilizes this tensor μ coupling, and have obtained good results experimentally, but the embodiment shown in FIG. is applied.

In FIG. 3, a coil 31 and a resonant capacitor 32 that resonates with the coil 31 are newly provided, and high frequency (microwave) energy from a high frequency oscillator 18 is supplied to this coil 31 via a high frequency coupling capacitor 19. Here, the thin film conductor (coil) 16 and the coil 31 are arranged orthogonally to each other as shown in the figure.

With this configuration, as described above, there is no electromagnetic coupling between the thin film conductor 16 and the coil 31 unless the magnetic body 15 is in a magnetic resonance state. However, due to the signal magnetic field from the magnetic recording medium 11, a current based on an electromotive force flows from the coil 13 of the ring-shaped magnetic head 12 to the coil 14, and this coil 1
4 and the high frequency from the high frequency oscillator 18 (
When the microwave (microwave) energy causes magnetic resonance, the thin film conductor 16 and the coil 31 are strongly coupled by tensor μ coupling due to this magnetic resonance, and this coupling generates a high frequency voltage at the output of the resonant circuit. Therefore, by detecting this high frequency voltage with the detection circuit 23 in the same manner as before, a reproduced output can be obtained.

In this reproduction method using tensor μ coupling, the coupling is almost zero outside the magnetic resonance state, and coupling occurs only when magnetic resonance occurs or is close to it by applying a magnetic field to the magnetic body 15. The magnetic field applied to the magnetic body 15, in other words, the change in the signal magnetic field from the magnetic recording medium 11 can be extracted as a larger change in the reproduction output, making it possible to reproduce with an extremely good S/N ratio, and to achieve ultra-high density reproduction. This is particularly advantageous for reproducing magnetically recorded signals.

FIG. 4 shows an embodiment in which the present invention is applied to a reproduction method using an MRH (magnetoresistive head), in which a coil 14 that generates a magnetic field by a current from a coil 13 of a ring-shaped magnetic head 12 is made of a permalloy film or the like. The magnetic field is wound around a magnetoresistive element 31 made of a magnetoresistive thin film, and the change in electrical resistance of the magnetoresistive element 41 caused by the magnetic field generated by the coil 14 is converted into a voltage change 13- for reproduction. That is, the magnetoresistive element 4
1 is connected to thin film electrodes 42 and 43, and the electrode 42
is grounded, and the electrode 43 is connected to the DC current 8I4 via the resistor 45.
Connected to 4. When the resistance of the magnetoresistive element 41 changes, the voltage generated across the magnetoresistive element 41 changes accordingly, and by extracting this voltage through the capacitor 46, a reproduced output can be obtained. In this embodiment as well, the thin film-like magnetoresistive element 41 is connected to the magnetic recording medium 11.
Since there is no need for direct contact with the material, the problem of wear can be solved.

FIG. 5 shows a modified example of the configuration shown in FIG. 4, in which thin wires made of a magnetoresistive material such as permalloy are folded or bundled as the magnetoresistive element 51.

In this way, MRH with better sensitivity can be achieved.

In each of the above embodiments, the coil 1 of the ring-shaped magnetic head 12
The case where the coil 14, which generates a magnetic field by receiving the current from 3, is directly wound around the magnetic material 15 or the magnetoresistive element 41°51 has been described, but as shown in FIG. A second ring-shaped magnetic head wound around a core made of a magnetic material may be constructed, and a magnetic body 15 similar to that described in FIG. 2 may be provided in close proximity to the magnetic gap 61a of this head. In this way, a magnetic field generated intensively in the magnetic gap 61a of the second ring-shaped magnetic head 61 can be applied to the magnetic material, so that changes in high frequency characteristics such as magnetic resonance can be caused more effectively. It has the advantage of being able to

It goes without saying that in this embodiment, the first ring-shaped magnetic head 12 can also be used as a recording head.

Furthermore, similar effects can be expected when the MRH is configured by placing a magnetoresistive element close to the magnetic gap 61a of the second ring-shaped magnetic head 61.

As explained above, according to the present invention, signal magnetic fields with high frequency components can be detected with higher sensitivity compared to methods in which the signal magnetic field is applied to a magnetic material or a magnetoresistive element, so the reproduction sensitivity and frequency characteristics are significantly improved. Effects can be obtained.

In the above-described embodiment, a ring-type magnetic head was used as a means for converting the signal magnetic field from the magnetic recording medium into an electromotive force, but the present invention is not limited to this. The same effect can be obtained if it can be converted into electromotive force by

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the basic principle of a magnetic recording signal reproducing method that utilizes changes in the high frequency characteristics of a magnetic material due to a signal magnetic field from a magnetic recording medium, and Figs. 2 to 6 show details of this invention. FIG. DESCRIPTION OF SYMBOLS 11... Magnetic recording medium, 12... Ring-type magnetic head for signal magnetic field detection, 13... Coil of magnetic head,
14... Coil for magnetic field generation, 15... Magnetic material (magnetic field detection element), 16... Thin film conductor, 17... Resonance capacitor, 18... High frequency oscillator, 19... For high frequency coupling Capacitor, 23... Peak detection circuit, 31... Coil, 32... Resonance capacitor, 41.51... Magnetoresistive element (magnetic field detection element), 61... Ring-shaped magnetic head for generating magnetic field. . Applicant's agent Patent attorney Takehiko Suzue 17- Figure 1

Claims (1)

[Claims] (1) means for converting a signal magnetic field from a magnetic recording medium into an electromotive force; a means for converting a current based on this electromotive force into a magnetic field; It is characterized by comprising a magnetic field detection element whose electrical resistance changes, and means for converting the high frequency characteristics or the change in electrical resistance of the magnetic field detection element into an electrical signal and reproducing the signal recorded on the magnetic recording medium. A magnetic recording signal reproduction method. (2>vA The magnetic recording signal reproducing method according to claim 1, wherein the means for converting the signal magnetic field of the magnetic recording medium into an electromotive force is a ring-type magnetic head. (3) Magnetic recording Magnetic recording according to claim 2, characterized in that the ring-shaped magnetic head for converting a signal magnetic field from a medium into an electromotive force is also used as a head for recording signals on a magnetic recording medium. Signal reproduction method. (4) The magnetic field detection by the magnetic field detection element utilizes changes in tensor magnetic permeability due to magnetic resonance at high frequencies due to the applied magnetic field.
The magnetic recording signal reproducing method described in . (5) The means for converting a current based on an electromotive force converted from a signal magnetic field from a magnetic recording medium into a magnetic field is provided so that when this current is supplied to a coil, a magnetic field is generated from the magnetic gap part. It is a ring type magnetic head,
2. The magnetic recording signal reproducing system according to claim 1, wherein the magnetic field detection element is arranged near the magnetic gap of the ring-shaped magnetic head.