JPS62219204A - Magnetic reproducing device - Google Patents

Abstract

PURPOSE:To form a magnetic reproducing device having excellent characteristic by connecting a high frequency oscillator and a detecting circuit to a resonance circuit using coupling of weak induction. CONSTITUTION:When a resonance circuit 4 of high Q is formed, Q of the resonance circuit 4 remains high even when inductance elements 21, 22 and a detecting circuit 8 are connected. Accordingly, when high frequency magnetic characteristic of magnetic substance 1 is changed by a signal magnetic field 7, Q and resonance frequency of the resonance circuit 4 change largely. Thereby, high frequency signals supplied to the resonance circuit 4 are subjected to large amplitude modulation. By detecting the signals by the inductance element 22 and passing through a detector circuit 8, the signals of large amplitude modulation can be reproduced.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a magnetic reproducing device for reproducing magnetically recorded signals, and in particular to a magnetic reproducing device for reproducing magnetically recorded signals, and in particular for detecting changes in the high frequency characteristics of a magnetic material due to changes in a signal magnetic field formed by a magnetic recording medium. The present invention relates to a magnetic reproducing device that is used to reproduce signals.

[Technical background of the invention and its problems]

A magnetic recording and reproducing device that is equipped with a magnetic material that detects changes in the signal magnetic field from a magnetic recording medium as changes in characteristics such as magnetic permeability and high-frequency loss, and that reproduces signals by utilizing changes in the inductance of a coil wound around this magnetic material. has been proposed (for example, Japanese Patent Laid-Open No. 57-36407).

FIG. 3 is a circuit diagram showing the operating principle of this magnetic recording/reproducing device. A resonant circuit 4 consisting of a coil 2 coupled to a magnetic body 1 for detecting a signal magnetic field and a tuning capacitor 3,
The high frequency (No. 8) from the high frequency oscillator 5 is supplied to the resonant circuit 4 through the coupling capacitor 6. The resonance frequency and sharpness Q change, and the high frequency signal undergoes amplitude modulation.The amplitude modulated signal is detected by a detection circuit 8 (here, as an example, a peak detection circuit consisting of a diode 9, a capacitor 10, and a resistor 11 is shown). A reproduced signal is obtained from the terminal 12 by detecting the signal.

In order to improve the sensitivity of this magnetic recording/reproducing device, it is necessary to increase the sharpness Q of the resonant circuit 4. However, in the circuit of FIG. 3, the resonant circuit 4 and the high-frequency oscillator 5 are coupled through a capacitor 6 (for example, a capacitance of 0.5 pF), and the resonant circuit 4 and the detection circuit 8 are directly coupled, so that the resonant circuit 4 Even if the Q of the resonant circuit 4 is increased, the Q of the resonant circuit 4 will decrease because these couplings are too strong. Therefore, in order to improve the sensitivity of this magnetic recording and reproducing device, it was necessary to couple the high frequency oscillator 5 and the detection circuit 8 so as not to reduce the Q of the resonant circuit 4.

[Purpose of the invention]

An object of the present invention is to provide a magnetic reproducing device with excellent characteristics that solves the above-mentioned problems.

[Summary of the invention]

The magnetic reproducing device according to the present invention is configured by connecting a high frequency oscillator and a detection circuit to a resonant circuit using a weakly inductive coupling.

〔Effect of the invention〕

According to the present invention, since weak inductive coupling is used when connecting the high frequency oscillator and the detection circuit to the resonant circuit, the original Q of the resonant circuit is not lowered by the connection. Therefore, a magnetic reproducing device having a high Q resonance circuit can be constructed, and highly sensitive signal reproduction becomes possible.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a circuit of one embodiment, in which a magnetic body 1 and a coil 2
A resonant circuit 4 composed of a tuning capacitor 3 and a tuning capacitor 3 is coupled to a high frequency oscillator 5 through a coupling inductance element 21.

Also, a diode 9, a capacitor 10. A detection circuit 8 consisting of a resistor 11 is also coupled to the common circuit 4 through a coupling inductance element 22. At this time, the inductance elements 21 and 22 and the resonant circuit generator are designed so that the inductive coupling between the inductance elements 21 and 22 and the resonant circuit 4 does not become strong. As a result, even if the high frequency oscillator 5, the detection circuit 8, and the resonant circuit 4 are coupled together, the Q of the resonant circuit 4 will not be lowered. Therefore, in the magnetic reproducing device of the circuit shown in FIG. 1, if the resonant circuit 4 with a high Q is created, the Q of the resonant circuit 4 will remain high even if the inductance elements 21 and 22 and the detection circuit 8 are connected. When the high frequency magnetic characteristics of 1 change due to the signal magnetic field 7, the Q of the resonant circuit 4 changes.
The resonance frequency changes greatly. Therefore, this resonant circuit 4
The high frequency signal supplied to the resonant circuit 4 undergoes large amplitude modulation, and this signal is detected by the inductance element 22.
By passing the signal through the detection circuit 8, a signal with large amplitude modulation can be reproduced.

FIG. 2 shows the configuration of a magnetic reproducing device according to another embodiment of the present invention. In the figure, a reproducing head 32 is formed on a non-magnetic insulating head substrate 31, and the following v
c. That is, a thin film-like magnetic material 1 is deposited near the tip of the substrate 31, and the i! A substantially U-shaped high-frequency coil 2 made of a thin film conductor is attached so that the coil 2 has a substantially U-shaped shape. A tuning capacitor 3 is connected to both ends of the coil 2, and the coil 2 and capacitor 3 constitute a resonant circuit 4.

An inductance element 21 for supplying a high frequency signal to this resonant circuit 4 and an inductance element 22 for detecting an output voltage from this resonant circuit 4 are arranged and created at symmetrical positions with the resonant circuit 4 in between. There is. This is because when the inductance elements 21 and 22 are placed adjacent to each other, the high frequency signal output from the inductance element 21 is transmitted to the resonant circuit 4.
This is because it is directly detected by the inductance element 22 without passing through. Since the approximately U-shaped inductance elements 21 and 22 can be made from thin film conductors, the coil 2
At the same time, it can be formed on the substrate 31. A high frequency oscillator 5 is connected to the inductance element 21 . The high frequency oscillator 5 has a frequency approximately equal to the resonant frequency of the resonant circuit 4;
For example, it is assumed that oscillation occurs at a frequency in the 2nd band or the 2nd band. Further, the detection circuit 8 is connected to the inductance element 22Vc.

For the detection circuit, a peak detection circuit consisting of a diode 9, a capacitor 10, and a resistor 11 as shown in the figure is used, for example.

As shown in the figure, the read head 32 configured as described above connects the end surface of the substrate 31 on the side where the magnetic material 1 is formed to the magnetic recording medium 4.
The recording track 42 is placed opposite to the recording track 42 on the top of the recording track 42 . When the magnetic recording medium 41 is run in the direction of the arrow 43 in this state, the magnetic body l receives the recording signal magnetic field from the magnetic recording medium 41,
In other words, a change in the magnetic field due to recording magnetization from the recording track 42 changes the high frequency magnetic characteristics, that is, the high frequency complex magnetic permeability.

A high frequency signal from a high frequency oscillator 5 is supplied to the resonant circuit 4 through a weak inductive coupling between the inductance element 21 and the coil 2. A high frequency magnetic field is generated from the coil 2 by this high frequency signal, and this high frequency magnetic field is applied to the magnetic body 1. As mentioned above, the high-frequency complex magnetic permeability (complex magnetic permeability for the high-frequency magnetic field generated from the coil 2) of the magnetic body 1 changes depending on the recording signal magnetic field. The resonant frequency and Q of the resonant circuit 4 change, and as a result, its high frequency signal output changes. Therefore, the change in the high frequency signal output is controlled by the coil 2.
The magnetic recording medium 4 is detected by the inductance element 22 which has a weak inductive coupling with the
1 (, the playback output for No. 4 is on terminal 1
This can be obtained from 2.

At this time, since the coupling between the coil 2 and the inductance elements 21 and 22 is weak inductive coupling, the Q of the resonant circuit 4 is not lowered by these couplings. Therefore, if the resonant circuit 4 is designed to have a high Q, the change in the high frequency signal in the resonant circuit 4 due to the change in the recording signal magnetic field will have a high Q.
It gets bigger because of it. Therefore, highly sensitive signal reproduction is possible.

FIG. 4 shows the configuration of a magnetic reproducing device according to another embodiment of the present invention, in which the output impedance between both terminals of the inductance element 21 of the same magnetic head 32 as in FIG. 2 is approximately equal to the output impedance of the high-frequency oscillator 5. A resistor 51 is connected thereto. By connecting the resistor 51, the output impedance of the high frequency oscillator 5 and the impedance between the terminals of the inductance element 21 are matched, and the efficiency with which the high frequency signal from the high frequency oscillator 5 is supplied to the inductance element 21 is improved.

FIG. 5 shows the configuration of a magnetic reproducing apparatus according to another embodiment of the present invention, in which capacitors 521r and m
IA, this inductance element 21 and capacitor 5
The resonant frequency of the resonant circuit constituted by 2 and the oscillation frequency of the high frequency oscillator 5 are made to almost match. By connecting the capacitor 52 to the inductance element 21 to form a resonant circuit, a high frequency signal from the high frequency oscillator 5 is concentrated in this resonant circuit VC. Therefore, a high frequency signal is efficiently supplied to the resonant circuit 41C.

FIG. 6 shows the configuration of a magnetic reproducing apparatus according to another embodiment of the present invention, in which a capacitor 53 is connected to the inductance element 22 of the magnetic head 32, which is the same as that shown in FIG. When detecting the high frequency signal modulated by the resonant circuit 4 with the inductance element 22 and using it as an input signal of the detection circuit 8, the input signal of the detection circuit 8 can be increased by connecting the capacitor 53 to the inductance element 22 and causing resonance. can do.

It goes without saying that the embodiments shown in FIGS. 4, 5, and 6 may be used in combination as necessary.

[Brief explanation of drawings]

zi diagram is a diagram showing a circuit of a magnetic reproducing device according to one embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a magnetic reproducing device according to another embodiment of the present invention, and FIG. 3 is a diagram showing a conventional circuit. Figure, Figure 4,
FIGS. 5 and 6 are diagrams showing the configuration of other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Magnetic material, 2... Coil, 3... Tuning capacitor, 4... Resonance circuit, 5... High frequency oscillator, 7
...Signal magnetic field, 8...Detection circuit, 12...Reproduction output terminal, 21.22...Coupling inductance element,
31... Head substrate, 32... Magnetic head, 41.
...Magnetic recording medium, 51...Resistance, 52.53...
Condensed length. Figure 1 Figure 3 Figure 2

Claims (5)

[Claims] (1) A magnetic material whose high-frequency characteristics change depending on the recording signal magnetic field from a magnetic recording medium; a resonant circuit that is coupled to this magnetic material and applies a high-frequency magnetic field to the magnetic material by being supplied with a high-frequency signal; a detection circuit that detects a change in high-frequency signal output from a resonant circuit due to a change in high-frequency magnetic properties of the magnetic material and reproduces the signal recorded on the magnetic recording medium; 1. A magnetic reproducing device characterized in that inductive coupling is used for coupling between a high frequency oscillator that generates oscillator and the resonant circuit, and for coupling between the resonant circuit and the detection circuit. (2) An inductance element that supplies a high-frequency signal from the high-frequency oscillator to the resonant circuit, and an inductance element that detects the high-frequency signal of the resonant circuit and supplies it to the detection circuit are arranged in symmetrical positions across the resonant circuit, 2. A magnetic reproducing device according to claim 1, wherein these three parts are formed on the side surface of a supporting base. (3) The magnetic reproducing device according to claim 1, wherein a resistor approximately equal to the output impedance of the high-frequency oscillator is connected between both terminals of an inductance element that supplies a high-frequency signal from the high-frequency oscillator to the resonant circuit. (4) A capacitor is connected between both terminals of an inductance element that supplies a high-frequency signal from a high-frequency oscillator to a resonant circuit, and the resonant frequency of the resonant circuit composed of this inductance element and the capacitor is approximately equal to the oscillation frequency of the high-frequency oscillator. A magnetic reproducing device according to claim 1. (5) A magnetic reproducing device according to claim 1, wherein a capacitor is connected to an inductance element for detecting a high frequency signal of a resonant circuit to cause resonance, and this resonant voltage is used as an input voltage of the detection circuit.