JPH0344363B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic reproducing device that performs reproduction by utilizing changes in characteristics of a magnetic material due to changes in a magnetic field formed by a magnetic recording medium.

[Technical background of the invention and its problems]

Conventionally, magnetic reproducing devices that reproduce signals recorded on magnetic recording media use ring-shaped magnetic heads.
The structure is such that the electromotive force induced by this is extracted as a reproduction output. However, this method is disadvantageous for high-density recording and reproduction because the reproduction output level and its S/N largely depend on the recording track width.
Currently, the recording track width is 20μ and the S/N ratio is about 43dB.

Therefore, the inventors have already proposed a magnetic reproducing device based on a new principle in Japanese Patent Application No. 110340/1983. This device is equipped with a magnetic material that detects changes in the magnetic field from a magnetic recording medium as changes in characteristics such as magnetic permeability and high-frequency loss, and uses changes in the impedance of an impedance element such as an inductance element or a capacitance element containing this magnetic material. It performs regeneration. That is, a tuning circuit is configured using the impedance element as part of a tuning element, and a high-frequency excitation signal from a high-frequency oscillator is supplied to this impedance element. in this case,
When the characteristics of the magnetic body change due to the magnetic field from the magnetic recording medium, and the impedance of the impedance element changes accordingly, the resonant frequency and Q (sharpness) of the tuned circuit change accordingly.
The high frequency signal output from the tuned circuit changes. Therefore, by detecting a change in the high frequency signal output through a detection circuit, a reproduced output corresponding to the signal recorded on the magnetic recording medium can be obtained.

According to this method, even the slightest change in the magnetic field formed by the magnetic recording medium is detected as a change in the characteristics of the magnetic material, and is extracted as a playback output.Since the playback output energy is supplied from a high-frequency oscillator, high-level and A reproduction output with a good S/N ratio can be obtained, and even if the recording track width is narrowed to 20 μm or less, sufficient reproduction can be performed.

As described above, although the system proposed in Japanese Patent Application No. 110340/1983 is in principle more suitable for high-density recording and reproduction than conventional magnetic reproducing devices, there is still a limit to its high density. In other words, in order to increase the recording density, it is possible to narrow the recording track width and shorten the recording wavelength, but in that case, if you try to reproduce using the above method, the width of the magnetic material must be made smaller to match the recording track width. However, it is also necessary to reduce the thickness of the magnetic material in accordance with the short recording wavelength. The reason for reducing the thickness of the magnetic material is that the magnetic field formed by the magnetic recording medium is stronger near the surface, and the shorter the recording wavelength is, the stronger the magnetic field is.
In other words, this tendency is stronger as the recording signal frequency is higher, and as the thickness increases, the magnetic field only reaches a portion of the magnetic material, and changes in the characteristics of the magnetic material due to changes in the magnetic field become smaller.

As described above, in order to perform higher density recording and reproduction, it is necessary to reduce the size of the magnetic body as much as possible, and accordingly, the size of the impedance element containing this magnetic body must also be reduced. However, as the dimensions of this impedance element are reduced, the influence of its stray capacitance cannot be ignored, and this stray capacitance makes it difficult to stably supply a high-frequency excitation signal to the impedance element, and also causes problems in the tuning circuit. Q decreases. As a result,
It becomes difficult to stably and efficiently convert changes in the characteristics of a magnetic material due to the magnetic field from a magnetic recording medium into electrical signals.

[Purpose of the invention]

The purpose of this invention is to provide a reproduction output with a sufficiently high S/N ratio even when the recording track width is very narrow.
It is an object of the present invention to provide a magnetic reproducing device that can be easily obtained.

[Summary of the invention]

This invention forms an inductance element that includes a conductive magnetic material as an interelectrode substance that detects a magnetic field formed by a magnetic recording medium, and forms a capacitance element that holds this inductance element between electrodes. By coupling a high-frequency excitation signal to the inductance element through the inductance element, the high-frequency excitation signal is supplied to a tuning circuit in which the inductance element is configured as a part of a tuning element, and magnetism due to a change in the magnetic field detected by the magnetic body is supplied. It is characterized in that the signal recorded on the magnetic recording medium is reproduced by detecting a change in the high frequency signal output of this tuning circuit due to a change in the characteristics of the body.

〔Effect of the invention〕

According to the present invention, for an inductance element that includes a conductive magnetic material as an interelectrode material that detects a signal magnetic field formed by a magnetic recording medium, the inductance element is held between electrodes, that is, it is provided so as to surround this inductance element. Because the high-frequency excitation signal is coupled through the capacitance, even if the dimensions of the magnetic material are reduced to accommodate ultra-high density recording and reproduction, the influence of the stray capacitance of the inductance element can be ignored due to the capacitance of the capacitance element. It becomes like this. Therefore, the high frequency excitation signal can be stably coupled to the inductance element, and the Q of the tuned circuit is not lowered.
Furthermore, the capacitance element has the effect of shielding electromagnetic fields other than the signal magnetic field and preventing them from acting on the inductance element.

Therefore, even in extremely high-density recording and reproduction where the recording track width is 20 .mu.m or less, there is no decrease in reproduction sensitivity, and reproduction output with a high level and good S/N ratio can be obtained.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention. In the figure, an inductance element 1 has plate-shaped metal electrodes 3a and 3b on both sides of a plate-shaped conductive magnetic body 2.
This inductance element 1 is formed by depositing the electrodes 6a and 6 of the capacitance element 4.
It is provided embedded in the dielectric 5 between the holes 5a and 5b. The inductance element 1 and the tuning capacitance element 7 constitute a first LC parallel tuning circuit 8. On the other hand, the capacitance element 4 similarly constitutes a second tuning circuit 10 together with the tuning inductance element 9. This second tuning circuit 10 is connected to a high frequency oscillator 12 via a matching circuit 11. Therefore, a high frequency excitation signal from the high frequency oscillator 12 is supplied to the inductance element 1 via the capacitance element 4. The first tuning circuit 8 includes a diode 13 and a resistor 1.
4 and a capacitor 15.
6.

In the magnetic reproducing device configured in this way,
When the inductance element 1 and the capacitance element 4 are opposed to the magnetic recording medium 18 on which a signal is recorded as shown in the figure, a magnetic field (signal magnetic field) that changes according to the recording signal from the magnetic recording medium 18 is applied to the magnetic body 2. , This changes the magnetic permeability or high frequency loss of the magnetic body 2. If a material whose magnetic permeability or high-frequency loss changes greatly with changes in the magnetic field, such as thinned permalloy, sendust, or amorphous magnetic alloy, is used as the magnetic body 2, the change in the magnetic permeability or high-frequency loss of the magnetic body 2 will Then, an inductance element 1 using this magnetic material 2 as an interelectrode material
The apparent inductance of the first tuned circuit 8 changes greatly, and as a result, the impedance of the first tuned circuit 8 composed of the inductance element 1 and the capacitance element 7 changes, so the voltage across the first tuned circuit 8 also changes. Change. That is, the high frequency excitation signal coupled to the inductance element 1 from the high frequency oscillator 12 is subjected to amplitude modulation in the first tuning circuit 8 by the signal magnetic field from the magnetic recording medium 18. Therefore, the high frequency signal output from the first tuning circuit 8 that has received this modulation is detected by the detection circuit 16.
By detecting the signal, the signal reproduction output Vout can be obtained.

With such a configuration, the stray capacitance of the inductance element 1 can be ignored due to the large capacitance of the capacitance element 4. Furthermore, since the stray capacitance of the capacitance element 4 is sufficiently smaller than the original capacitance, it can also be ignored. Therefore, the high-frequency excitation signal can be stably coupled and supplied from the high-frequency oscillator 12 to the inductance element 1, and the Q of the first tuned circuit 8 can be suppressed from decreasing due to the influence of stray variables of the inductance element 1. Therefore, even signals recorded at high density on a very narrow track can be reproduced at a sufficient level and with a good S/N ratio.

FIG. 2 shows another embodiment of this invention,
One electrode 3b of the inductance element 1 in FIG. 1 is connected to one electrode 6b of the capacitance element 4.
By using the same structure, the structure is simplified and the number of manufacturing steps is reduced.

The present invention is particularly advantageous when applied to a multichannel magnetic reproducing apparatus that simultaneously reproduces data from a plurality of recording tracks. 3 to 6 show examples thereof, in which a plurality of inductance elements 1 are provided in one capacitance element 4. In this case, each of the inductance elements 1 will be supplied with a high frequency excitation signal via the common capacitance element 4.

Therefore, compared to the case where high-frequency excitation signals are individually coupled and supplied to the inductance element 1, there is no variation in the coupling degree for each channel, and variation in reproduction output level can also be suppressed. Moreover,
The structure of the excitation circuit including the coupling part and the high-frequency oscillator 12 is simple, and the wiring is simplified, which is advantageous in terms of process, and the advantage is that integrated circuit technology such as LSI can be effectively utilized.

The embodiment shown in FIG. 3 is a multi-channel version of the structure of the embodiment shown in FIG. 1, whereas the embodiment shown in FIG. The body 2 is integrally formed.

The embodiment shown in FIG. 5 is similar to the embodiment shown in FIG. 2, in which one electrode 3b of the inductance element 1 is shared with one electrode 6b of the capacitance element 4, resulting in a multi-channel structure.

In the embodiment shown in FIG. 6, each magnetic body 2 of the inductance element 1 in FIG. 5 is further formed integrally.

As is clear from the figures, the structure and manufacturing process are successively simplified in the order of FIGS. 3, 4, 5, and 6.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention;
FIG. 2 is a cross-sectional view showing the main structure of another embodiment of the invention, FIG. 3 is a diagram showing an embodiment in which the invention is applied to a multi-channel magnetic reproducing device, and FIGS.
The figure is a cross-sectional view showing the main structure of another embodiment in which the present invention is applied to a multi-channel magnetic reproducing device. 1... Inductance element, 2... Conductive magnetic material,
3a, 3b... Electrode, 4... Capacitance element, 5
... Dielectric, 6a, 6b... Electrode, 8... First tuning circuit, 10... Second tuning circuit, 12... High frequency oscillator, 16... Peak detection circuit.

Claims (1)

[Scope of Claims] 1. An inductance element including a conductive magnetic material as an interelectrode material for detecting changes in a magnetic field formed by a magnetic recording medium; a tuning circuit configured with this inductance element as part of a tuning element; a capacitance element holding an inductance element between its electrodes; excitation means for coupling a high frequency excitation signal to the inductance element via the capacitance element; A magnetic reproducing apparatus comprising means for detecting a change in high frequency signal output and reproducing a signal recorded on the magnetic recording medium. 2. The magnetic reproducing device according to claim 1, wherein one electrode of each of the inductance element and the capacitance element is made common. 3. The magnetic reproducing device according to claim 1 or 2, characterized in that a plurality of inductance elements are provided between the electrodes of the capacitance element. 4. The magnetic reproducing device according to claim 1, wherein the excitation means couples a high frequency excitation signal to the inductance element via a tuning circuit in which a capacitance element is a part of the tuning element.