JPS647458Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) This invention relates to a magnetic head that integrates a recording/reproducing head and an erasing head, and is suitable for use in high recording density floppy disks.

(Prior Art) As magnetic heads for magnetic drums, magnetic disks, magnetic tapes, etc., there are known magnetic heads in which erasing heads are integrally arranged on both sides of a recording/reproducing head. More specifically, this magnetic head is
For example, as is well known in Japanese Patent Publication No. 44-17679, the recording/reproducing gap 2 of the recording/reproducing head 1 as shown in FIG. Erasing heads 3 and 4 are arranged on each side of the track.
The erase gaps 5 and 6 are parallel to each other (tunnel erase method), or the recording/reproducing gap 2 and the erase gaps 7 and 8 are at right angles to each other as shown in FIG. 2 (straddle erase method).
Alternatively, as shown in FIG. 3, a device is known in which the erasing gaps 9 and 10 are inclined at an angle of 0 to 90 degrees with respect to the recording/reproducing gap 1.

In such a magnetic head, when a recording track is formed on a recording medium by the recording/reproducing head 2 during recording, an erasing current is simultaneously applied to the erasing heads 3 and 4 to erase both sides of the recording track. This is to trim the side edges of the recording tracks, thereby increasing the track density and ultimately increasing the density of the recording medium.

However, when such a magnetic head is used, as shown in FIG. It is often the case that the target is off. In such a case, erase gap 5 of erase head 3
picks up the magnetic field of the recording track B to be reproduced, and the erase gap 6 of the erase head 4
may also pick up the magnetic field of the adjacent track _B1 . The magnetic flux caused by the magnetic field picked up by the erase gaps 5 and 6 is diverted to the recording/reproducing head 1 side as noise magnetic flux, reducing the S/N of the recording/reproducing head.

This phenomenon is particularly noticeable when the recording/reproducing gap and the erasing gap, and thus the core of the recording/reproducing head and the core of the erasing head, are very close to each other due to manufacturing constraints, such as in magnetic heads for floppy disks. Furthermore, in the magnetic head using the tunnel erase method shown in FIG. 1, since the magnetic path of the recording/reproducing head and the magnetic path of the erasing head are parallel,
Significant. Furthermore, as shown in FIGS. 5 and 6, when a back pole (or back bar) 11 is added to the erase heads 3 and 4 to form a closed magnetic circuit structure, the erase gap 5 The noise magnetic flux picked up by , 6 is recorded as shown by the arrow /
The flow is diverted to the reproduction head 1 side, and this phenomenon is remarkable.

Therefore, at present, erasure heads 3 and 4 are designed to have an open magnetic path structure without providing a backpole for the erase head, and to increase the magnetic resistance against the magnetic flux picked up by the erase gap being shunted to the recording/reproducing head. Measures have been taken to prevent coupling of the recording/reproducing head and to prevent deterioration of the S/N of the reproduced signal due to noise magnetic flux picked up by the erase gap.

However, recently, in order to achieve higher density, it is necessary to increase the coercive force Hc of recording media such as floppy disks (Currently, Hc is about 300 Oe,
It is expected that it will eventually reach around 600 to 700 Oe. ),
Therefore, as the coercive force Hc of the recording medium increases, the erasing efficiency of the erase head with an open magnetic path structure without backpoles as described above decreases, making complete erasing difficult. Furthermore, in open magnetic path structures, external noise magnetic fields are often picked up from sources other than the erase gap.

Furthermore, an erasure gap 9,1 as shown in FIG.
In the case where 0 is tilted, the erasure gap is 9, 10.
Azimuth loss can suppress crosstalk from adjacent tracks that are read out, but it is not very effective against other noises.

(Purpose of the invention) The purpose of this invention is to prevent magnetic coupling between the erasing head and the recording/reproducing head in a magnetic head where the recording/reproducing head and the erasing head are very close to each other. The object of the present invention is to prevent the S/N ratio of the reproduced signal from deteriorating due to the noise magnetic field picked up by the magnetic field, and to increase the erasing efficiency by making the erasing head have a closed magnetic circuit structure.

(Structure of the invention) Therefore, this invention is characterized in that a capacitor is connected in parallel with the erasing head coil to reduce the high frequency noise picked up by the erasing gap.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

In FIG. 7, 12 is a recording/reproducing head;
3 is a recording/reproducing gap, and 14 is a recording/reproducing head coil. The erase heads 15, 16 have erase gaps 17, 18 and back poles 19, 18.
20 is added to form a closed magnetic circuit structure. Reference numeral 21 denotes an erase head coil, and a capacitor 23 is connected in parallel with this erase head coil 21.

When the erase head coil 21 is short-circuited by the capacitor 23 in this way, the erase head coil 2
Since there is no high frequency magnetic field in the erase head 1, no high frequency noise can exist within the erase head core. Since the noise voltage induced in the recording/reproducing head coil 14 has a high frequency, the short circuit noise reduction effect by the capacitor 23 is large. Furthermore, since the erasing head of the magnetic head for floppy disks uses direct current erasing, even if the erasing head coil 21 is short-circuited at high frequency with a capacitor in this way, no problem will occur in the erasing operation of the erasing heads 15 and 16.

Furthermore, since magnetic coupling between the erase heads 15, 16 and the recording/reproducing head 12 is prevented at high frequencies, back poles 19, 20 can be added to make the erase heads 15, 16 have a closed magnetic circuit structure. This improves erasing efficiency, allows the use of recording media with high coercive force Hc, and enables higher density. Furthermore, the closed magnetic circuit structure increases resistance to external noise.

Note that even when the erase head has an open magnetic path structure, the short circuit caused by the capacitor 23 has a noise suppressing effect to some extent.

Furthermore, high frequency noise has the effect of reducing not only crosstalk from adjacent tracks but also all high frequency noise. For noise whose frequency is known to some extent, such as crosstalk, the capacitance of the added capacitor 23 is appropriately selected, and a resonant circuit consisting of the capacitance of the capacitor 23 and the inductance of the erasing head coil 21 is created. By setting the resonance frequency to the frequency of the noise to be suppressed, the effect of suppressing the noise can be increased. (however,
If Q is made too high, ringing will occur when the erase current is turned on and off. ) Note that the capacitance of the capacitor 23 is preferably about 100 pF to 14 μF.

In addition, this invention is particularly suitable for application to the tunnel erase method magnetic head for floppy disks (Fig. 7), but it is also suitable for the straddle erase method (Fig. 8) and the method in which the erase gap is provided diagonally (Fig.
In the case of (Fig.), there is a similar noise reduction effect.

In FIG. 8, 12 is a recording/reproducing head, 13 is a recording/reproducing gap, 14 is a coil for the recording/reproducing head, 25 is an erasing head, 26, 2
7 is an erase gap, 28 is a back pole, 29 is an erase head coil, and 30 is a capacitor.

(Effects of the invention) As explained above, according to this invention, by connecting a capacitor in parallel with the erasing head coil, magnetic coupling between the erasing head and the recording/reproducing head is prevented at high frequencies, and the erasing gap is prevented. It is possible to prevent deterioration of the S/N of the reproduced signal due to the high frequency noise magnetic field picked up by the magnetic field. If the frequency of the noise is known to some extent, the noise can be easily reduced by appropriately selecting the capacitance of the capacitor. Furthermore, since the erasing head can have a closed magnetic path structure, erasing efficiency is improved, a recording medium with a high coercive force can be used, and a high density recording medium can be realized.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the gap surface of a magnetic head using a conventional tunnel erase method, Figure 2 is a plan view showing a gap surface of a magnetic head using a conventional straddle erase method, and Figure 3 is a plan view showing a gap surface of a magnetic head using a conventional straddle erase method. 4 is a plan view showing the relationship between the magnetic head and the track, FIG. 5 is a front view of the magnetic head shown in FIG. 1, and FIG. 1 and 5 are perspective views of the magnetic head, FIG. 7 is a perspective view of one embodiment of the magnetic head according to this invention, and FIG. 8 is a perspective view of another embodiment of the magnetic head of this invention. . 12... Recording/playback head, 13... Recording/playback gap, 14... Recording/playback head coil, 15, 16, 25... Erase head, 17, 1
8, 26, 27...Elimination gap, 19, 20,
28... Back pole, 21, 29... Erase head coil, 23, 30... Capacitor, B,
B ₁ ... Truck.

Claims (1)

[Claims for Utility Model Registration] (1) In a magnetic head that integrates a recording/reproducing head and an erasing head that forms erasing tracks on both sides of the track recorded by the recording/reproducing head, a coil for the erasing head is provided. A magnetic head characterized by having a capacitor connected in parallel with the magnetic head. (2) Claim 1 of the utility model registration in which the capacitance of the capacitor is selected so that the resonance frequency of the resonant circuit composed of the capacitance of the capacitor and the inductance of the erasing head coil becomes the frequency of the noise to be suppressed. Magnetic head as described. (3) The magnetic head according to claim 1, wherein the capacitor has a capacitance of 100 pF to 1 μF.