JPH01184709A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To attain high density magnetic recording capable of being used also for reproducing and having high sensitivity and a high SN ratio by forming a recording one-turn coil and a reproducing one-turn coil in a magnetic circuit consisting of a magnetic film. CONSTITUTION:A step up transformer 8 connected to a recording circuit 9 is connected to the recording coil 7 so as to record a signal on a magnetic recording medium by allowing current to flow into the coil 7. On the other hand, capacitors 10, 11 are connected to the reproducing coil 6 in parallel to constitute a high frequency tuning circuit and a means 12 for supplying high frequency and a means 13 for detecting the peak of a change in a high frequency voltage appearing the turning circuit in accordance with a change in a signal magnetic field obtained from a magnetic recording medium are connected to the tuning circuit. Consequently, a high recording density signal can be reproduced with high sensitivity and a high SN ratio.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention relates to a thin film magnetic head for both recording and reproduction, with high sensitivity and high signal-to-noise ratio, suitable for use in high-density magnetic recording devices. It is something.

(Prior art) As shown in Fig. 11, conventional inductive thin film magnetic heads are capable of recording and reproducing with the same head. is expected to be in short supply. In order to solve this problem, a magnetic reproducing head based on a new principle has already been proposed in Japanese Patent Application No. 55-110340. This head is equipped with a magnetic film that detects changes in the signal magnetic field from the magnetic recording medium as changes in characteristics such as high-frequency transmittance and high-frequency loss, and uses changes in the complex inductance of a coil coupled to this magnetic film to generate recording signals. It is used for reproducing. That is, the above-mentioned coil constitutes a tuned circuit together with a capacitor, and a high frequency signal is supplied to this tuned circuit from a high frequency oscillator. In this case, the characteristics of the magnetic film change due to the signal magnetic field from the magnetic recording medium, and the complex inductance of the coil coupled thereto changes.

Along with this, the resonant frequency and/or Q (sharpness) of the tuned circuit
As a result, the high frequency voltage generated in the tuning circuit changes6.Therefore, by detecting this high frequency voltage change using a detection circuit, a reproduced output corresponding to the signal recorded on the magnetic recording medium can be obtained. According to this method, the reproduction sensitivity can be significantly improved compared to the conventional induction type magnetic head, and it becomes possible to reproduce signals recorded at a higher density with a higher signal-to-noise ratio.

As mentioned above, the magnetic head based on the method proposed in Japanese Patent Application No. 110340/1987 is in principle more suitable for high-density magnetic recording than the conventional induction type magnetic head or induction type thin film magnetic head, but it is not suitable for signal reproduction. Because it is a dedicated head,
With this head alone, in the conventional signal technology described above, firstly, the inductive thin film magnetic head can be used for both recording and reproduction, but its low reproduction sensitivity makes it difficult to reproduce future high-density signals with a good S/N ratio. Secondly, since the new type of magnetic head proposed to solve this problem is a read-only head, it has the disadvantage that it cannot record signals by itself.

The object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a thin film magnetic head suitable for high-density magnetic recording that can be used for both recording and reproduction, and has high sensitivity and a high signal-to-noise ratio.

In order to achieve this object, the present invention aims to create a thin-film magnetic head that is capable of both recording and reproducing functions and has higher reproducing sensitivity than conventional inductive thin-film magnetic heads. A 1-turn coil exclusively for recording and a 1-turn coil exclusively for reproduction are formed using thin film formation technology, and a step-up transformer connected to a recording circuit is connected to the recording-only coil, and a current is passed through the coil. This enables signal recording on magnetic recording media,
On the other hand, a capacitor is connected in parallel to the read-only coil to constitute a high frequency tuning circuit, and the tuning circuit includes means for supplying high frequency waves, and means for supplying high frequency waves to the tuning circuit according to changes in the signal magnetic field from the magnetic recording medium. High sensitivity and high SN can be achieved by connecting a means to peak detect the changes in the high frequency voltage that appears.
This makes it possible to reproduce high recording density signals with a high ratio.

(Function) According to the present invention, since it is possible to reproduce signals with higher reproduction sensitivity and signal-to-noise ratio than conventional inductive thin film magnetic heads, it is possible to record and reproduce signals at a higher recording density than before.
Furthermore, recording and reproducing can be performed with the same head, and the manufacturing process is simpler than that of conventional inductive thin film magnetic heads, and the manufacturing yield can be increased.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a thin film magnetic head according to the present invention, in which a lower magnetic film 2, an insulating layer 5, and a first turn are formed by using a thin film forming process technology on a substrate 1. In a thin film magnetic head in which a coil 7, a second one-turn coil 6, and an upper magnetic film 4 are sequentially formed, the first
A recording circuit 9 is connected to the one-turn coil 7, and the second one-turn coil 6 constitutes a high-frequency tuning circuit together with a capacitor 10, and this tuning circuit is supplied with a high-frequency wave composed of a capacitor 11 and a high-frequency oscillator 12. The means and the peak detection circuit 13 are connected. Recording on the magnetic recording medium is achieved by passing a recording signal current from the recording circuit 9 to the first one-turn coil 7. On the other hand, when reproducing the signal recorded on the magnetic recording medium, the current is changed according to the signal. The change in the high frequency voltage generated on the high frequency tuning circuit may be detected using the peak detection circuit 13.

According to this embodiment, it is possible to realize a thin film magnetic head that has higher reproducing sensitivity than conventional inductive thin film magnetic heads and is capable of both recording and reproducing. Furthermore, using this embodiment, the coil is 2
Since it is only necessary to form two one-turn coils, the manufacturing of the head is easier than with conventional thin film magnetic heads which require multiple turns of coils, and the yield can be expected to increase.

Next, other embodiments will be described.

FIG. 2 is a perspective view showing a second embodiment, in which a step-up transformer 8 connected to a recording circuit 9 is connected to the first one-turn coil 7, and the other parts are the same as in FIG. It is the same as the example. When this embodiment is used, by increasing the number of windings on the recording circuit 9 side of the step-up transformer 8 compared to that on the one-turn coil 7 side, the number of windings required for the recording circuit is reduced compared to the embodiment shown in FIG. The recording current value can be reduced, and it becomes possible to use the conventional recording circuit for a multi-winding thin film magnetic head as is.

FIG. 3 is a perspective view showing a third embodiment, in which the first one-turn coil 7 and the second one-turn coil 6 are different from the embodiments shown in FIGS. The lower magnetic films 2 and 7 are formed on the upper magnetic film 4 side, and other components are similar to the embodiments shown in FIG. 1 or 2.

FIG. 4 is a perspective view showing a fourth embodiment, in which a first one-turn coil 7 and a second one-turn coil 6 are formed approximately parallel to the substrate 1 in the middle of the insulating film 5. This is an example. Using this embodiment, two one-turn coils can be connected to the insulating layer 5.
Unlike the embodiments shown in FIGS. 1, 2, and 3, which are formed in two layers with a 1-turn coil 6.7 in the middle,
It has the advantage that it can be manufactured by a thin film formation process of several layers.

FIG. 5 is a perspective view showing a fifth embodiment, in which the positions of the first one-turn coil 7 and the second one-turn coil 6 are reversed from those in the embodiment of FIG. It has the same advantages as the embodiment shown.

6 and 8 show a sixth embodiment.

FIG. 6 is a top view of this, and FIG. 7 is a sectional view taken along line AA' in FIG. In this embodiment, a step-up transformer 14 connected to a first one-turn coil 7 used as a recording coil is placed on a substrate 1 on which the main part of the thin-film magnetic head is formed, using the same thin film forming process technology as that for the main part. 14 consists of magnetic films 17, 18, a coil 16, an insulating film 19, etc. Using this embodiment, a more compact thin film magnetic head can be manufactured than the previous embodiment.

FIG. 8 is a side view showing the seventh embodiment, in which a hard magnetic film 21 is formed on top of the upper magnetic film 4 with a non-magnetic insulating film 20 interposed therebetween, and this is magnetized. A bias static magnetic field can be applied to the upper magnetic film.

By selecting the dimensions and material properties of 21, the thickness of 20, etc., it is possible to apply an optimal bias static magnetic field to the upper magnetic film 4 in order to reproduce signals with high sensitivity and excellent linearity. Note that 21 may be a conductive coil instead of the hard magnetic film, and by passing an appropriate direct current through this coil, the same effect as described above can be achieved.

FIG. 9 is a schematic diagram showing the eighth embodiment.
It consists of a resistor 23 and a DC power source 24, and is connected to a step-up transformer 8 connected to a recording circuit and a means for passing a DC current through the circuit. Switch 2 when recording
2 into the step-up transformer 8 side. At the time of reproduction, by switching the switch 22 to the circuit side through which the DC current flows, a DC current is caused to flow through the first one-turn coil 7, and as a result, the upper magnetic film 4 and/or the lower magnetic film 2 are exposed to the embodiment shown in FIG. This makes it possible to apply the optimal bias static magnetic field as explained above. If this embodiment is used, the first one-turn coil 7 can be used both as a recording coil and as a coil for applying a bias static magnetic field to the magnetic pole during reproduction. There is no need to form a hard magnetic film or conductive coil.

Note that the constituent elements mainly for playback in this embodiment are similar to those in the previous embodiment.

FIG. 10 is a perspective view of the ninth embodiment.
A high frequency amplifier 25 is connected between a high frequency tuning circuit consisting of a one-turn coil 6 and a capacitor 10 and a peak detection circuit 13, which amplifies the high frequency on the high frequency tuning circuit that changes according to the signal recorded on the magnetic recording medium. It is something.

By using this embodiment, it is possible to reproduce the recorded signal with a higher SN ratio than by directly peak detecting the change in the high frequency voltage on the high frequency tuning circuit.

Although the embodiments of the present invention have been described in detail above, the present invention can be applied to longitudinal recording systems, perpendicular recording systems, and any other magnetic recording system.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to realize a thin-film magnetic head that has higher reproduction sensitivity than conventional inductive thin-film magnetic heads and is capable of both recording and reproduction. , it becomes possible to record and reproduce higher-density signals with a higher signal-to-noise ratio. Furthermore, regarding the coil that is a component of the head, since it is only necessary to fabricate one turn of thin film coil for each of recording and reproduction, it is easier to fabricate the head compared to the conventional multi-winding inductive thin film magnetic head. Manufacturing yields also improve.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the invention, FIG. 2 is a perspective view showing another embodiment of the invention, and FIGS. 3 to 5 are perspective views showing other embodiments of the invention. FIG. 6 is a plan view showing another embodiment of the present invention, FIG. 7 is a sectional view taken along line AA' in FIG.
FIG. 8 is a side view showing another embodiment of the invention, FIG. 9 is a schematic diagram showing another embodiment of the invention, FIG. 1θ is a perspective view showing another embodiment of the invention, and FIG. The figure is a cross-sectional view for explaining the prior art. 1... Substrate 2... Lower magnetic film 3... Gap layer 4... Upper magnetic film 5... Insulating film 6... Second one turn coil 7... First one turn Coil 8...Step up transformer 9...Recording circuit 10...Tuning capacitor 11...High frequency coupling capacitor 12...High frequency oscillator 13...Peak detection circuit 14...Thin film step up transformer 15a , 15b
"Terminal 16...Thin film coil 17...Magnetic film 18...Magnetic film 19...Recording film 20...Nonmagnetic insulating film 21...Hard magnetic film or conductive coil 22... Switch 23...Resistor 24...DC power supply 25...High frequency amplifier Representative Patent attorney Noriyuki Chika Yudo Mitsuyuki Matsuyama Figure 2 Figure 4 Figure 5 Figure 8

Claims (6)

[Claims] (1) In a thin film magnetic head comprising a lower magnetic film, an insulating film, a coil, and an upper magnetic film sequentially formed on a substrate, the coil is composed of a first one-turn coil and a second one-turn coil, and the coil is composed of a first one-turn coil and a second one-turn coil; The first one-turn coil is a coil for recording signals on the magnetic recording medium, the second one-turn coil is a coil for reproducing the signal recorded on the magnetic recording medium, and the first one-turn coil is a coil for recording signals on the magnetic recording medium. A recording circuit is connected to the coil, and the second one-turn coil constitutes a high frequency tuning circuit with a capacitor, and this tuning circuit includes a means for supplying high frequency and a means for responding to changes in the signal recorded on the magnetic recording medium. 2. A thin film magnetic head, further comprising means for detecting a peak of a change in the high frequency voltage on the tuning circuit that appears in the tuning circuit. (2) The thin film magnetic head according to claim 1, wherein a step-up transformer connected to the recording circuit is connected to the first one-turn coil. (3) The thin-film magnetic head according to claim 2, wherein the step-up transformer is formed on the substrate using a thin-film forming technique. (4) A hard magnetic film or a coil is formed on the upper magnetic film via a non-magnetic insulating film using a thin film forming technique, and a bias static magnetic field is applied to the upper magnetic film. The thin film magnetic head described. (5) The thin film magnetic head according to claim 1, wherein the first one-turn coil is also used as a coil for applying a bias magnetic field to the upper magnetic film and the lower magnetic film during signal reproduction. . (6) Amplify the high frequency voltage appearing on the high frequency tuned circuit,
2. The thin film magnetic head according to claim 1, wherein the signal is reproduced by detecting a peak of a change in the amplified high frequency voltage according to the signal recorded on the magnetic recording medium.