JPS59213016A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To execute recording with a high density on a flexible disk by providing a self-degaussing circuit consisting of an LC resonance circuit on a magnetic head driving circuit. CONSTITUTION:When a driving current is made to flow to a driving coil of a magnetic head, a magnetic energy stored in the driving coil is utilized, and after de-energizing is completed, an AC current which is attenuated together with a time generated by a self-degaussing circuit 2 added newly is made to flow to the driving coil, and degaussing of the magnetic head is executed so as to improve a degaussing operation of the magnetic head to a recording medium. When a switch SW is closed, namely, when an erasing magnetic head 1 is operated, an erasing current iE is equal to a current of a DC constant-current source E. Accordingly, when the AC current, which is attenuated as oscillating, is made to flow to an erasing coil LE, a residual magnetic flux density can be reduced by its AC degaussing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The first object of the present invention is to provide a magnetic recording device which is useful not only as a general magnetic recording device but also as a magnetic recording device for recording at a high density of 5% on a flexible disk. It is in.

Another object of the present invention is to provide a magnetic head drive circuit that can improve performance by simply adding a relatively simple circuit.

It is well known that magnetic recording devices using flexible disks have recently been widely used to improve office efficiency due to their ease of use. Research aimed at this purpose is underway.

The present invention has also been made as a means to achieve this objective. ``The magnetic material for the magnetic head of the magnetic recording device for flexible disks currently in general use has a coercive force of about 300 oersteds.

On the other hand, magnetic materials with a large coercive force of about 600 oersteds are used as magnetic materials for high recording density.

Although a large coercive force means a strong resistance to demagnetization, it also reduces the residual magnetism of the magnetic head because it requires a large magnetic field strength for recording and erasing. Since it becomes larger, it causes inconvenience.

That is, if the residual magnetism of the erasing magnetic head is large, the reproduction output amplitude of the recorded data will be reduced due to the demagnetizing effect of the erasing magnetic head as it slides over the data recorded on the magnetic medium. Therefore, the playback performance will be affected.

Therefore, one object of the present invention is to provide an excellent magnetic recording device in which the residual magnetism of the magnetic head is small.

In other words, the present invention utilizes the magnetic energy stored in the drive coil when the drive current is flowing through the drive coil of the magnetic head, and after the deenergization is completed, the alternating current that decays over time is generated by the newly added self-demagnetization circuit. is applied to the drive coil to demagnetize the magnetic head, thereby improving the demagnetizing effect of the magnetic head on the recording medium.

FIG. 1 is an explanation of the principle of the present invention, in which the horizontal axis shows the strength of the magnetic field H1, and the vertical axis shows the magnetic flux density B.

In a conventional magnetic recording device, when the direct current flowing through the drive coil is cut off, the magnetic flux density of the magnetic head at 11 points during drive is demagnetized in the direction of the arrow, and the residual magnetic flux density becomes Bl, but below that This causes a problem because it does not decrease.

In the present invention, after the drive current rB is cut off, a self-attenuating AC demagnetizing current is caused to flow as shown in FIG. 2, so that the magnetic flux density converges to zero.

If we compare Figures 1 and 2, we can see that B shown in Figure 1 is
-H1ill@! The 21 points above correspond to the erase current IN in FIG. 2, and the 22 points correspond to 2.

When the current flowing through the drive coil changes as shown in Figure 2, the B-H characteristic changes from P1 to P on the B-H curve shown in Figure 1.
2 → Ps... and the residual magnetic flux density changes from B1 → B2 →
It becomes smaller as Bs→...

The present invention provides a magnetic head drive circuit with a self-demagnetizing circuit composed of an LO resonance circuit that functions as described above.

The following is a description of an embodiment in which the Kinei BA is applied to an erasing magnetic head.

FIG. 3 shows an embodiment of the present invention, in which 1 is an erase magnetic head, 2 is an LOR resonant circuit provided between the erase current control switch SW and the erase magnetic head 1, E is a DC constant current source b, and LB is a This is the internal resistance of the erasing coil, r-trout erasing coil Lll.

Here, the erase current is iB, the natural angular frequency is ωn, and the angle is φ
and the inductance of the erasing coil LB is IF3 [H3
, the resistance value of the internal resistance rH of the erasing coil 'fc rncΩ
].

(However, γB #0) h The inductance of the coil L connected in series to the erase coil is L [HJ & the values of the capacitor C and the resistor connected in parallel to the power supply are each 0FF) %
When it is 几〔Ω〕, when the switch SW is closed.

That is, when the erasing magnetic head 1 is working, the erasing current is 1B.
is equal to the current of the DC constant current source E.

In this state, the erase current 3F+(t) when the switch SW is opened at the t=0 point in Fig. 2 is expressed by the following equation (1)... (1) φ-t a n-" convex: ...(
It is season ζ.

In the above formula, set 几, 0. so that ζ becomes 1. If you choose L, (
Type 1 produces attenuated vibration as shown in Figure 2.

Therefore, by flowing an alternating current that oscillates and attenuates in this way through the erasing coil LH, the residual magnetic flux density can be reduced by the alternating current demagnetizing effect.

In the embodiment shown in FIG. 3, the resistor may be omitted in some cases.

FIG. 4 shows a different embodiment. In contrast to the one shown in FIG. 3 in which a capacitor and a resistor are connected in series with respect to a DC constant current source E, when they are connected in series, T, L , O
A similar function can be achieved by appropriately selecting the values of , and .

Although an embodiment has been described above in which the present invention is applied to an erasing magnetic head of a magnetic recording device using a continuous disk, the present invention can also be applied to an erasing magnetic head of a general magnetic recording device.

A point to note regarding application to a general erasing magnetic head is that the recording remains on the medium due to the damped vibration turbulence after erasing. The grain does not limit the application of the present invention.

Also, here we have explained the case where a direct current is passed through the erasing magnetic head, but the principle of the present invention is to use the magnetic energy stored in the erasing coil for demagnetization, so the erasing current is turned off. Since it is related only to the erasing current when the current is applied, it can also be applied to erasing magnetic heads that flow alternating current.

It is also applicable to a data writing head.

Note that the inductance L connected in series with the erasing coil is 1
This is not essential and may be unnecessary depending on the inductance value of the erase head.

Therefore, it should be understood that the present invention is not limited to only those exemplified herein.

[Brief explanation of the drawing]

FIG. 1 is a B-H curve diagram for detailed explanation of the present invention;
Figure 2 shows the erase current characteristics in the present invention. 3 and 4 are electrical circuit diagrams of embodiments of the present invention, respectively.

Claims (1)

[Claims] (1) A magnetic recording device characterized by providing a self-demagnetizing circuit consisting of an LO resonance circuit in the erasing magnetic head drive circuit. (2) A magnetic recording device characterized in that a write magnetic head drive circuit is provided with a self-demagnetizing circuit consisting of an LO resonant circuit having a resonant frequency that does not cause resonance with the fill-in signal.