JPS5911504A - Magnetic reproducer - Google Patents

Abstract

PURPOSE:To obtain a reproduced output having a sufficiently large level with good S/N even for a very narrow recording track width, in a magnetic reproducer for reproducing signals by using the change in characteristics of a magnetic substance due to the change in a magnetic field formed with a magnetic recording medium. CONSTITUTION:The 1st capacitance element 1 is formed by covering plate- shaped metallic electrodes 3a, 3b on both sides of a plate-shaped insulating magnetic substance 2 so as to be embedded in a dielectric 5 of electrodes 6a, 6b of the 2nd capacitive element 4. The 1st capacitive element 1 constitutes the 1st LC parallel tuning circuit 8 together with a tuning inductance element 7. The 2nd capacitive element 4 forms similarly the 2nd tuning circuit 10 together with a tuning inductance element 9. The 2nd tuning circuit 10 is connected to a high frequency oscillator 12 via a matching circuit 11. Thus, a high frequency exciting signal from the high frequency oscillator 12 is coupled with the 1st capacitive element 1 via the 2nd capacitive element 4 in the form of an electric field by means of the capacitive coupling. Further, the 1st tuning circuit 8 is connected to a peak detecting circuit 16 comprising a diode 13, a resistor 14 and a capacitor 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic reproducing device that performs reproduction by making use of 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, a magnetic reproducing apparatus for reproducing mail recorded on a magnetic recording medium uses a ring-shaped magnetic head, and is configured to extract the electromotive force induced in the ring-shaped magnetic head as a reproducing 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 trunk width, and currently the recording track width is 20 μm.

The S/N is said to be at a limit of about 43 dB.

Therefore, the inventors have already proposed a magnetic reproducing device based on a new principle in Japanese Patent Application No. 110340/1982. 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.
Reproduction is performed using changes in impedance of an impedance element such as an inductance element or a capacitance element containing this magnetic material. That is, a tuning circuit is configured using the impedance element as part of a tuning collector, 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 seven impedance elements changes, the resonant frequency and Q (sharpness) of the tuned circuit change accordingly.
changes, so the high frequency signal output from the tuned circuit changes. Therefore, by detecting the change in the high frequency signal output through the detection N path, 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.The playback output energy is also supplied from a high-frequency oscillator. level and S/N
A good reproduction output can be obtained, and even if the recording track width is narrowed to 20 μm or less, sufficient reproduction can be performed.

As mentioned above, although the system proposed in % Application No. 110340/1988 is theoretically 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 reduce the recording density, it is possible to narrow the recording trunk width and shorten the recording wavelength, but in that case, if you try to use the above method for restraint, the width of the magnetic material will need to be adjusted to match the recording trunk width. In addition, it is necessary to reduce the thickness of the magnetic material to match the short recording wavelength. The reason for reducing the thickness of the magnetic material is that the magnetic field formed by a magnetic recording medium is stronger near the surface, and this tendency is stronger the shorter the recording wavelength, that is, the higher the recording signal frequency. This is because when the magnetic field becomes larger, the magnetic field only reaches a part of the amphoteric material, and the change in the characteristics of the magnetic material due to changes in the magnetic field becomes 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 the tuning circuit Q decreases. As a result, it becomes difficult to stably and efficiently convert changes in the characteristics of the magnetic material due to the magnetic field from the magnetic recording medium into electrical signals.

[Purpose of the invention]

An object of the present invention is to provide a magnetic reproducing apparatus that can obtain a sufficiently high level reproduction output with a good S/N ratio even when the recording trunk width is very narrow.

[Summary of the invention]

This invention forms a first capacitance element that includes an insulating magnetic material as an interelectrode storage device for detecting a magnetic field formed by a magnetic recording medium, and a second capacitance element that holds this first capacitance element between electrodes. a tuned N-path in which the first capacitance element is configured as part of a tuning collector by forming an element and coupling a frequency excitation signal to the first capacitance element through the second capacitance element; A current frequency excitation signal is supplied to the magnetic body, and a change in the Akane frequency signal output of this tuned circuit is detected due to a change in the characteristics of the magnetic body due to a change in the magnetic field detected by the magnetic body, and a signal recorded on the magnetic recording medium is detected. The feature is that it plays 5 times.

〔Effect of the invention〕

According to this invention, the number a magnetic field formed by the magnetic recording medium is
A first capacitance element that includes an insulating magnetic material as an interelectrode material that detects a field is held at an electrode [SAJ, that is, a second capacitance element provided to surround this first capacitance element. Since the high-frequency excitation signal is coupled through 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 first capacitance element will be reduced by the valley of the capacitance cord of M2. can be reduced by Therefore, the high frequency excitation signal can be stably coupled to the first capacitance element, and the Q of the tuning circuit is not lowered. Furthermore, the second capacitance element has the effect of shielding electromagnetic fields other than the signal magnetic field and preventing them from acting on the first capacitance element. Therefore, if the recording track width is 20 μm or less, ultra-high density recording such as 5. Even during recording and reproduction, there is no reduction in reproduction sensitivity, and reproduction output at a high level and with a good S/N ratio can be obtained.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention. In the figure, a first capacitance cable 1 is formed by attaching plate-shaped metal electrodes 3a and 3b to both sides of a plate-shaped insulating magnetic material 2. Dielectric material 5 between electrodes 6a and 6b of capacitance element 4 of No. 2
It is installed in a way that it is embedded inside. The first capacitance element 1 together with the tuning inductance element 7
LC parallel tuning circuit 8 is constructed. On the other hand, the second 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 1. Therefore, the high frequency excitation signal from the high frequency oscillator 12 is coupled to the first capacitance element 1 via the second capacitance element 4 in the form of an electric field due to capacitance coupling. The first tuning circuit 8 is connected to a peak detection circuit wJ16 consisting of a diode 13, a resistor 14, and a foundation/substrate 15.

In the magnetic reproducing apparatus configured as described above, when the first and second capacitance elements 1.4 are oriented crosswise as shown in the figure, the magnetic recording medium 18 on which a signal is recorded at -° C. A magnetic field (signal magnetic field) that changes according to the recording No. 4M is applied to the magnetic body 2, thereby changing the magnetic permeability or cylinder circumferential V loss of the magnetic body 2. If the magnetic material 2 is made of a material whose magnetic permeability and high-frequency loss change greatly in response to changes in the magnetic field, and which also has extremely low electrical conductivity, such as thin spinel or garnet thread ferrite, the permeability of the magnetic material 2 may be reduced. Due to changes in magnetic property and high frequency loss, the apparent capacitance of the first capacitance element 1 using the magnetic material 2 as an interpole material changes greatly, and as a result, the relationship between the first gear pantance element 1 and the inductance element 7 changes significantly. Since the impedance of the first F[141 times Bg composed of Bg changes, both 14 voltages of this first tuned circuit 8 also change.

That is, the high frequency excitation signal coupled from the high frequency oscillator 12 to the first capacitance element 1 is amplitude-changed W by the signal magnetic field from the magnetic recording medium 18 in the first tuning circuit 8.
You will receive many.

Therefore, by detecting the high frequency signal output from the first tuning circuit 8 that has undergone this modulation using the detection circuit 16, the signal reproduction output vout can be obtained.

With this configuration, the first capacitance cable 1
The stray capacitance of the second capacitance wire 4 is large for each t
In addition, since the second capacitance cable 4Q) is sufficiently small compared to the original number of customers, it can also be ignored.
It becomes possible to stably couple and supply the local frequency excitation link from Since the W4 circuit sv)q can be suppressed, even signals recorded in a very narrow trunk can be reproduced at a sufficient level and with a good S/N ratio.

FIG. 2 shows another embodiment of the present invention, in which one electrode 3b of the first capacitance element 1 in FIG. 1 is shared with one electrode 6b of the second capacitance element 4. The aim is to simplify the structure and reduce the number of manufacturing steps.

This invention is extremely useful, especially when applied to a multi-channel magnetic reproducing apparatus that simultaneously performs recording from a plurality of self-recording trunks. 3 to 6 show examples thereof, in which a plurality of first capacitance elements 1 are provided within one second capacitance element 4. in this case,
Each of the first capacitance elements 1 is supplied with a high frequency excitation signal via a common second capacitance element 4.

Therefore, compared to the case where the image frequency excitation signal is individually coupled and supplied to the first capacitance element 1, there is no variation in the degree of coupling 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 allows effective use of integrated N-path technology such as LSI. There is a U point.

For example, 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. Each magnetic body 2 is integrally formed.

The embodiment shown in FIG. 5 has multiple channels by making one electrode 3b of the first capacitance element 1 common to one electrode 6b of the second capacitance element 4, as in the embodiment of FIG. It is something.

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

As is clear from the figure, the structure and manufacturing process are as shown in Figure 3.
4, 5, and 6 are simplified in this order.

[Brief explanation of the drawing]

FIG. 1 shows the structure of one embodiment of the invention, and FIG. 2 shows the main structure of another embodiment of the invention. FIG. 3 is a diagram showing an embodiment in which the present invention is applied to a multi-channel magnetic reproducing device, and FIGS. 4 to 6 show other embodiments in which the present invention is similarly applied to a multi-channel magnetic reproducing device. FIG. 3 is a cross-sectional view showing the main part configuration of an example. DESCRIPTION OF SYMBOLS 1...Kx capacitance element, 2...Insulating magnetic material, 3a, 3b...Electrode, 4...pA2 capacitance element, 5.Dielectric material, 6a, 5b...Electrode, 8
...first tuned circuit", 1o...second tuned circuit,
12... Frequency booster, 16... Peak detection enclosure.

Claims (4)

[Claims] (1) A first capacitance element that includes an insulating magnetic material as an interelectrode material that detects changes in the magnetic field formed by a magnetic recording medium, and a tuning circuit that includes this first capacitance element as part of a tuning element. , a second capacitance element holding the first capacitance element between the electrodes, and a high frequency vibration excitation signal is coupled to the Ail Hd first capacitance element through the second capacitance element. It is characterized by comprising an excitation means and a means for detecting a change in the high frequency signal output of the tuning circuit due to a change in the characteristics of the magnetic body due to a change in the magnetic field and reproducing the signal recorded on the magnetic recording medium. magnetic reproducing device. (2) A magnetic reproducing device according to item 1 of the scope of Patent M*, characterized in that one electrode of each of the first capacitance element and the second capacitance element is shared. (3) A magnetic reproducing device according to claim 1 or 2, characterized in that a plurality of first capacitance elements are provided between the electrodes of the second capacitance element. (4) The excitation means couples an excitation signal to the first capacitance element via a tuning circuit in which the second capacitance element is a part of the tuning element. The magnetic reproducing device according to scope 1.