JPH02263304A - Thin film magnetic reproducing head - Google Patents

Abstract

PURPOSE:To attain the magnetic reproducing with high sensitivity and a high SN ratio by preparing a 1st thin film magnetic core which detects the signal magnetic flux produced from a magnetic recording medium and a 2nd thin film magnetic core which is connected to a high frequency coil to obtain the output voltage in response to the signal magnetic flux or a magnetic film separately from each other and connecting these cores and film to each other via a coil of a closed loop. CONSTITUTION:A 1st thin film magnetic core 2 touches a magnetic recording medium and runs to detect the signal magnetic flux produced by magnetization of a recording signal. Then a signal current flows to a 1st thin film coil 4 in response to the change of the signal magnetic flux. This signal current induces the signal magnetic flux to a 2nd thin film magnetic core 3. As a result, the core 3 changes the high frequency characteristics in response to the signal magnetic flux. Thus the high frequency voltage changes in a high frequency tuning circuit in response to the signal magnetic flux when the high frequency voltage is supplied to the tuning circuit from a high frequency source 7. Therefore the signals recorded on the magnetic recording medium can be reproduced with high sensitivity and a high SN ratio with use of a peak detecting means.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a thin film magnetic reproducing head.

(Prior Art) Figure 4 shows an example of a conventional thin-film magnetic reproducing head that reproduces recorded signals by converting changes in the high-frequency characteristics of a magnetic film in response to changes in signals recorded on a magnetic recording medium into voltage changes. show.

In this example, a one-turn thin film coil 4 is linked to a closed magnetic circuit type thin film magnetic core 2 having a magnetic gap on the opposing surface 10 of a magnetic recording medium, and this coil 4 is connected in parallel with a capacitor 11 to create a high frequency tuning circuit. One of both ends of the coil 4 is grounded, and the other end is connected to a high frequency voltage source 7 via a capacitor 6 for supplying a high frequency voltage to the high frequency tuning circuit, and furthermore, the coil 4 is connected to a high frequency voltage source 7 which supplies a high frequency voltage to the high frequency tuning circuit. The thin-film magnetic reproducing head is connected to both ends of the peak detecting means for detecting a change in the high-frequency voltage generated in the high-frequency tuning circuit corresponding to a change in the high-frequency characteristics of the thin-film magnetic core 2 induced accordingly.

This reproducing head has extremely high signal reproducing sensitivity compared to conventional inductive magnetic heads, and is therefore expected to be applied to future high-density magnetic recording devices. However, when the magnetic pole width in the track width direction is gradually narrowed for the purpose of narrow track recording, below a certain width, the playback output is faster than the degree of decrease in track width due to the influence of the demagnetizing field distribution within the magnetic pole. There was a problem with decreasing speed. therefore,
In order to achieve even higher track density recording in the future, it was necessary to develop a device and technology that would allow the playback output to be proportional to the track width even if the track width was made smaller.

(Problem to be Solved by the Invention) As described above, conventional thin-film magnetic reproducing heads have the disadvantage that when the recording track width becomes less than a certain value, the reproduction output decreases at a faster rate than the track width decreases. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a thin film magnetic reproducing head that can reproduce signals with high recording track density with high sensitivity and a high signal-to-noise ratio.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a first yoke-shaped thin film core that has a magnetic gap at a position facing a magnetic recording medium and picks up signal magnetic flux from the magnetic recording medium; a first thin film coil having a closed loop structure interlinking with the thin film core; a second thin film core having a closed magnetic path structure interlinking with the first thin film coil; and a second thin film coil interlinking with the second thin film core. a thin film coil, a tuning capacitor connected in parallel to the second thin film coil and forming a tuning circuit with the second thin film coil, one of both ends of the second thin film coil being grounded and connected to the other. and a peak detection circuit connected to both ends of the second thin film coil to detect changes in the high frequency voltage occurring in the tuned circuit. It is a magnetic head.

(Function) According to the present invention, a first thin film magnetic core for detecting a signal magnetic flux from a magnetic recording medium and a second thin film magnetic core coupled to a high frequency coil for obtaining an output voltage according to the signal magnetic flux. Since the core or the magnetic film is provided separately and these are connected to each other by a closed loop coil, the track width of the first thin film magnetic core or the first thin film magnetic core can be reduced in order to narrow the track. If the entire thin-film magnetic core is made smaller, the core's magnetic properties tend to deteriorate, the efficiency of picking up the signal magnetic flux from the magnetic recording medium decreases, and the core's high-frequency properties deteriorate even more. Since the second thin-film magnetic core can be configured to be larger than the first thin-film magnetic core, even if the track width of the first thin-film magnetic core is reduced, there will be no noticeable decrease in reproduction sensitivity. . As a result, narrow track recording and reproduction can be performed with higher sensitivity and a higher signal-to-noise ratio compared to the conventional case in which recording signals are reproduced using only the first thin-film magnetic core.

Furthermore, since the first thin-film core that detects the signal magnetic flux from the magnetic recording medium and the second thin-film magnetic core that converts the signal magnetic flux into voltage changes are provided separately, thin-film magnetic Even if it is necessary to apply a static bias magnetic field to the core or magnetic film, it is only necessary to apply this static bias magnetic field to the second thin film magnetic core or magnetic film, so the bias magnetic field is not applied to the first thin film magnetic core. Therefore, there is no risk of inadvertently erasing the recorded signal magnetization on the magnetic recording medium during signal reproduction.

(Embodiment) FIG. 1 is a front view showing a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA' of the embodiment shown in FIG. A closed magnetic path type first thin film magnetic core 2 having a magnetic gap on the recording medium facing surface 10 and a completely closed magnetic path type second thin film magnetic core 3 separate therefrom are formed,
A closed first thin film coil 4 with one turn is formed so as to interlink with both the first thin film magnetic core 2 and the second thin film magnetic core 3, and interlink with the second M film magnetic core 3. A second thin film coil 5 is formed as shown in FIG. A high frequency source 7 for supplying a high frequency voltage to the high frequency tuning circuit is connected via a capacitor 6 to both ends of the high frequency tuning circuit. A peak detection means 8 for detecting a change in the high frequency voltage is connected, and when the first thin film magnetic core 2 contacts and travels against the magnetic recording medium and detects the signal magnetic flux from the recording signal magnetization, the change is detected. In response, a signal current flows through the first thin film coil 4, and this signal current induces a signal magnetic flux in the second thin film magnetic core, which causes the second thin film magnetic core 3 to change its high frequency characteristics in accordance with the signal magnetic flux. As a result, when a high frequency voltage is supplied from the high frequency source 7 to the early tuning circuit, the high frequency voltage changes in the early high frequency tuning circuit according to the signal magnetic flux. The signals recorded above can be reproduced with high sensitivity and a high signal-to-noise ratio.

If the first thin film coil 4 is formed to have as low an electrical resistance value as possible, almost the same signal magnetic flux as the signal magnetic flux flowing into the first thin film magnetic core 2 will be induced in the second thin film magnetic core 3. - For boat fishing, just the first three-film magnetic core 2 is used to suck up the signal magnetic flux from the magnetic recording medium and perform the magnetic-electrical processing of the signal, similar to the conventional thin-film magnetic reproducing head shown in Fig. 4. It is possible to obtain a reproduction output that is almost comparable to the case where conversion is performed, and when the track width of the first thin-film magnetic core 2 is narrowed in order to narrow the recording track, as shown in Fig. 4. In the conventional example, as the magnetic properties of the first thin-film magnetic core 2 change, the magnetostatic properties of the thin-film magnetic core deteriorate as the width becomes smaller below a certain track width, but at higher speeds this high frequency Characteristics deteriorate,
As a result.

It is known that the signal reproduction output deteriorates faster than the degree of track width reduction. However, if this embodiment is used,
If the track width of the first membrane magnetic core 2, which detects the signal magnetic flux from the recording medium via the magnetic gap, is reduced, the magnetostatic characteristics will deteriorate; Since the part where the conversion is performed is the joint part between the second thin film magnetic pole 3 and the thin film coil 5, if the width of the second thin film magnetic core 3 is kept above a certain value, at least the second thin film magnetic core 3 Since this method does not cause deterioration of the magnetostatic properties and high-frequency properties of the magnetostatic properties, it has the great advantage of making it possible to reproduce signals with high sensitivity and a high signal-to-noise ratio even if the recording track is significantly narrowed compared to conventional methods. can get.

In addition, in the conventional example, in order to optimally adjust the sensitivity and S/N ratio, it is necessary to apply a static bias magnetic field to the pancreatic magnetic core by some method, which erases the signal magnetization recorded on the magnetic recording medium. I was worried that it would get lost. However, according to the present embodiment, the static bias magnetic field need only be applied to the second thin-film magnetic core 3 without being applied to the first thin-film magnetic core 2, so the above-mentioned concerns are eliminated. As described above, according to this embodiment, it is possible to easily obtain a thin film magnetic reproducing head with a narrow track, high sensitivity and high S/N ratio, and the degree of freedom in designing the head can be greatly increased. In addition, since it can be manufactured using almost the same process as the conventional example, the equipment cost is 1.
There is no fear of an increase in -.

FIG. 3 is a front view showing another embodiment according to the present invention,
A closed-loop first thin film coil 4 is linked to the first pancreatic magnetic core 2 similar to the embodiment shown in FIG. A magnetic film 3 is provided through the layer 12, and an insulating layer 14 is further formed on this.
A second thin film coil 5 is provided via the magnetic film 3, and the coil 5 and the magnetic film 3 are coupled to each other, and the first thin film magnetic core 2 detects the signal magnetic flux from the magnetic recording medium in response to a change in the signal magnetic flux detected by the first thin film magnetic core 2 from the magnetic recording medium. A signal current is passed through the thin film coil 4 of the magnetic film 3, and as a result, a change in the high frequency characteristics is induced in the magnetic film 3.
When a high frequency voltage is supplied to the high frequency tuning circuit consisting of 1, the high frequency voltage changes according to the signal magnetic flux, and this is detected by the peak detection means 8, thereby controlling the signal recorded on the magnetic recording medium with high sensitivity. Moreover, it can be reproduced with a high signal-to-noise ratio. In addition, in this embodiment, as shown in the figure, by providing film-type magnets 13(a) and 13(b) on the substrate 1, the static bias magnetic field necessary for signal reproduction with high sensitivity and high S/N ratio can be applied to the magnetic field. A configuration can be adopted in which the bias can be applied only to the film 3 and the same bias is not applied to the first thin film magnetic core. As a means for applying a static bias magnetic field to the magnetic film 3, in addition to using a magnet as described above, a thin film coil for applying a static bias magnetic field may be placed close to the magnetic film 3, and an appropriate DC current may be passed through it. There is no harm in taking it.

Further, this embodiment has the same effects as the embodiment shown in FIG.

〔Effect of the invention〕

According to the present invention, magnetic recording signals with narrower tracks can be reproduced with higher sensitivity and a higher signal-to-noise ratio than conventional thin-film magnetic reproducing heads, and the static bias magnetic field necessary for optimizing the reproduction output can be reduced. Since it is only necessary to apply the voltage to the second thin-film magnetic core, there is no need to apply the voltage to the first thin-film magnetic core that faces the magnetic recording medium at the magnetic gap, so there is no risk of erasing the recorded signal magnetization on the magnetic recording medium. is obtained. Furthermore, there is no fear that the process will become more difficult than in the prior art, and the degree of freedom in head design is greatly increased.

[Brief explanation of drawings]

FIG. 1 is a front view showing one embodiment of the present invention, and FIG. 2 is a front view showing one embodiment of the present invention.
FIG. 3 is a front view showing another embodiment of the present invention, and FIG. 4 is a diagram showing an embodiment of the thin film magnetic reproducing head. 1...Substrate 2...First aF magnetism collecting core 3...Second thin film magnetic core 4...First thin film coil 5...Second thin film coil 6...Capacitor 7... High frequency voltage source 8...Peak detection means 9...Head protective layer 10...Surface facing the magnetic recording medium Agent Patent attorney Noriyuki Chika Yudo Hikaru Matsuyama Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] a yoke-shaped first thin film core that has a magnetic gap at a position facing the magnetic recording medium and picks up signal magnetic flux from the magnetic recording medium; and a first thin film with a closed loop structure that interlinks with the first thin film core. a coil, a second thin film core with a closed magnetic circuit structure interlinked with the first thin film coil, a second thin film coil interlinked with the second thin film core, and in parallel with the second thin film coil. a tuning capacitor that is connected to the second thin film coil and forms a tuning circuit; one of both ends of the second thin film coil is grounded, and a high frequency voltage source that is connected to the other end and supplies a high frequency voltage to the tuning circuit; and a peak detection circuit connected to both ends of the second thin film coil to detect a change in high frequency voltage occurring in the tuning circuit.