JPS63127402A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the magnetic interference with a low cost and to improve the reliability of a magnetic disk device by holding circuits between recording and reproducing coils and load resistances of a magnetic head, which is not in the recording and reproducing state, in the open state. CONSTITUTION:Head assembles 2a and 2b are arranged correspondingly to both magnetic surfaces 1a and 1b of a magnetic medium 1. In these assemblies 2a and 2b, magnetic circuits are formed in recording and reproducing cores 4a and 4b having recording and reproducing gaps 3a and 3b and recording and reproducing coils 5a and 5b are wound around them. Erasing cores 7a and 7b having erasing gaps 8a and 8b are coupled to cores 4a and 4b through magnetic insulting layers 6a and 6b and erasing coils 9a and 9b are wound around them. Load resistances 10a and 10b for matching to the impedance of recording and regenerative amplifiers of connection destinations are connected to coils 5a and 5b, and resistances 10 and 10b are cut off by switching circuits 11a and 11b. When assembles 2a and 2b are selected by a head side selecting circuit 12, circuits between coils 5a and 5b and resistances 10a and 10b are held open.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a double-sided recording type magnetic disk device, and particularly to prevention of magnetic interference between magnetic heads of the magnetic disk device.

[Conventional technology]

In recent years, various magnetic disk devices have come to be used as information recording devices, and among these types of devices, flexible disk devices have come to be particularly popular. As flexible disk devices have come into widespread use, various improvements have been attempted, and as a result, so-called double-sided flexible disk devices that use flexible disk media on which information is recorded on both sides have become mainstream in order to increase the storage capacity f1. It was decided to occupy This double-sided flexible disk device has two recording and reproducing magnetic heads corresponding to both sides of a flexible disk medium. Although the nine magnetic heads are not used for simultaneous recording and reproducing, magnetic interference caused by the fact that both are placed close to each other has become a problem. In other words, when a recording operation is performed on one side of the flexible disk medium corresponding to this magnetic head by flowing a recording current to the magnetic head on the side selected by the circuit, the leakage magnetic flux generated in this recording current is This is a problem in that the noise flows into a non-selected magnetic head on the opposite side of the flexible disk medium, and a noise signal is recorded on one side of the non-selected side of the flexible disk medium. Therefore, various proposals have been made in the past for the purpose of solving such problems. FIGS. 4 and 5 show an example of a countermeasure published in Japanese Unexamined Patent Publication No. 17912/1983, which is one of such proposals. Head slider assembly Q shown in Fig. 4
D indicates a recording/reproducing core 4 having a recording/reproducing gap (22a), an erasing head (c) arranged on both sides of this recording/reproducing core wire, and this erasing head @? The slider (C) consists of a slider Q4) formed of ceramics, a slider (C), and a slider holding plate to which these sliders (24, @ are bonded).
A magnetic shielding plate (E) is attached. When the head slider assembly Q1J described above is incorporated into the apparatus, it is disposed close to both sides of the recording medium (1) together with a helad slider assembly (21') having a configuration similar to that shown in FIG. will be established. If the head slider assembly H side is selected and a recording operation is to be performed on one side of the recording medium (1) facing above, when the recording/reproducing core (2) is excited, the recording/reproducing core (2) is excited. The leakage magnetic flux from the slider assembly (21') on the opposite side is directly
Therefore, in order to completely prevent the writing of noise signals to the non-selected side of the recording medium (1) due to this leakage magnetic flux flowing into the recording and reproducing core (22'). In addition, a magnetic shielding plate (c) described above and a magnetic shielding plate (2-way head slider assembly 21) (21') similar to the above-mentioned magnetic shielding plate are respectively disposed in the center so as to absorb all leakage magnetic flux. I have to. Furthermore, the sixth factor is the above-mentioned FC proposal, JP-A-61-12.
The countermeasures published in Publication No. 0308 are shown. The outline of the magnetic head drive circuit shown in FIG. 6 is based on the case where a recording operation 2 is performed on the magnetic surface (1b) of the magnetic surfaces (1a) and (1b) of a flexible medium, that is, a recording medium (1). is connected from the recording current supply circuit aG to the recording/reproducing coil (5
This recording/reproducing coil (5) is activated by passing a current through a).
a) generates magnetic flux, and this magnetic flux flows into the recording/reproducing core (4a
) and reaches the recording/reproducing gap (3a), where the signal is recorded on the surface of the recording medium (1a). At this time, excess leakage magnetic flux generated in the recording/reproducing coil (5a) directly flows into the recording/reproducing core (4b) of the head assembly (2b) on the non-selected side, so that this leakage magnetic flux is used for recording/reproducing. Gap (3b
), in order to prevent the noise signal from being written to the recording medium (1b) via the recording/reproducing coil (5b), a canceling current for canceling this leakage magnetic flux is applied to the non-selected side, that is, the recording/reproducing coil (5b) @, in synchronization with the recording current supply. The canceling current is supplied to the canceling current supply circuit αη via the circuit.

[Problem that the invention seeks to solve]

However, the above-mentioned ratio measures have problems as shown below. First of all, the method using magnetic shielding plates shown in Figures 4 and 5 tends to be expensive due to the necessity of processing extremely small parts, and
The method of flowing the canceling current shown in the figure has the problem that the circuit is complicated, and the setting of the canceling current value is delicate and not necessarily effective.

This invention was made to solve the above-mentioned problems, and provides a magnetic disk device that is low cost and highly reliable and has measures to prevent magnetic interference. The purpose is to obtain.

[Means for solving problems]

The magnetic disk device according to the present invention includes a power supply selection means for selectively supplying current to the recording and reproducing coils respectively disposed in each magnetic head, and a power supply selection means for selectively supplying current to each of the recording and reproducing coils and each of the recording and reproducing coils. Switching means, which is kept open while the magnetic head is not in a recording or reproducing state, is connected between each load resistor connected to the reproducing coil.

[Effect]

This invention focuses on the effect of leakage magnetic flux flowing into the non-selected magnetic head and suppresses the secondary voltage induced in the non-selected magnetic head, thereby effectively preventing the writing of noise signals.

[Embodiments of the invention]

FIG. 1 is an explanatory diagram of a magnetic head portion of a magnetic disk device showing an embodiment of the present invention, in which magnetic surfaces (1a) for magnetic recording are provided on both sides of a recording medium (11),
(1b) is formed. Each of these magnetic surfaces (1a)
, a head assembly (2a) corresponding to (1b),
(2b) is placed. Head assembly (2a) ij
, a recording/reproducing core having a recording/reproducing gap (3a) e (
4a) constitutes a magnetic circuit, around which a recording/reproducing coil (5a) is wound. This recording/playback core (4
a) magnetic insulating layer (68) e through the erase gap (8
An erasing core (7a) having a) is joined, and an erasing coil (9a) is wound around the erasing core (7a). Similar to the head assembly (2a) described above, the head assembly (2b) is also disposed at a symmetrical position with respect to the recording medium (1). Further, the recording/reproducing coils (5a), (5b) have load resistors (10a), (10b) for matching the impedance of the recording/reproducing amplifier (not shown) to which they are connected.
are connected, and the load resistance (10a) is connected to the switching means, that is, the switch circuits (11a) and (11b).
, (10b). (1'
Reference numeral 2 denotes a power supply selection means, ie, a head side selection circuit, which selects the side of the head and supplies a recording current. In the magnetic disk drive configured in this way, when the head assembly (2a) is selected and data is recorded on the magnetic surface (1a), the head side selection circuit a2 selects the head assembly (2a).
A current is supplied to the center tap of the recording/reproducing coil (5a) in a). When this head side selection circuit α2 is activated, the switch circuit (11a) is activated to connect the load resistance (10a) on the selection side and at the same time, the load resistance (10b) on the non-selection side is opened. (1tb) is linked. In this way, the recording/reproducing coil on the non-selected side is always open, and no short-circuit current due to electromagnetic induction flows. Therefore, it is possible to suppress the writing of noise signals to an extremely low level.

Here, FIG. 2 is used to help understand the present invention.

An explanatory diagram of a recording operation of a magnetic disk device is shown. First, in order to record data on the magnetic surface (1a) of the recording medium +11, the head assembly (2a) is selected, and a recording current of 1 W is supplied from the center tap of the recording/reproducing coil (5a).
It is assumed that magnetic flux is flowing through the recording/reproducing core (4a). At this time, magnetic fluxes φA, φB, and φC are generated in the figure, but the one involved in data recording is the recording/reproducing gap (3
a) Only φ people passing through.

The other φB and φC become leakage magnetic flux and interlink with the recording/reproducing core (4b) on the non-selected side. This leakage magnetic flux φB
Is the recording/reproduction gap (GB) on the direct non-selection side? When passing, a noise signal is written on the magnetic surface (1b).

In addition, the recording/reproducing coil (5b) is connected to the recording/reproducing coil (5b) on the non-selected side by electromagnetic induction via the load resistor (11b) which is directly connected to the end of the coil. A short-circuit current I flows through, causing a magnetic flux φF to flow in the opposite direction to φC. Due to the magnetic flux φF caused by this short-circuit current, an even larger amount of magnetic flux passes through the recording/reproducing gap (3b) on the non-selected side, resulting in a total increase in the noise signal.

In other words, the smaller the load resistance (11b), the smaller the I
As P increases, the noise signal becomes larger. by the way,
Generally, the load resistance value of the magnetic head of a flexible disk device is small in this sense, and therefore it is no exaggeration to say that this load resistance determines the noise signal writing fik. Figure 3 shows an example of writing a noise signal. When the load resistance is large, the short-circuit current IP is small and the noise signal is only the direct leakage of φB, which is practically negligible. It represents what will happen. Therefore, the load resistance is determined by the balance between the magnetic head and the recording/reproducing circuit.

Large values are difficult to obtain. Therefore, this invention was made to solve this problem.

〔Effect of the invention〕

As described above, according to the present invention, the connection between the recording/reproducing coil of the magnetic head that is not in the recording/reproducing state and the load resistor is maintained in an open state, so that it is possible to prevent magnetic interference at low cost. Done.

This has the effect of providing a highly reliable magnetic disk device.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a magnetic head portion of a magnetic disk device according to an embodiment of the present invention, FIG. 2 is an operational explanatory diagram for explaining the recording operation of the magnetic head portion in FIG. 1, and FIG. 3 is an explanatory diagram of noise A characteristic diagram showing an example of signal writing; FIGS. 4 and 5 are a perspective view and a side sectional view of a magnetic head slider in a conventional magnetic disk device; FIG. 6 is a circuit showing a head drive circuit according to another conventional example. It is a diagram. In the figure, (1) is the recording medium, (2a) (2b)
is the head assembly, (5a) (sb) is the recording/reproducing coil, (1oa) (1ob) is the load resistance, (11
a) (11b) is a switch circuit, and α is a head side selection circuit. In addition, in FIG. 2, the same reference numerals indicate the same or similar parts.

Claims (1)

[Claims] In a magnetic disk drive equipped with two magnetic heads that face each other via a magnetic recording medium capable of recording on both sides and respectively perform recording, reproduction, and erasing on the magnetic recording medium, each of the magnetic heads is provided with a A power supply selection means is provided for selectively supplying current to the installed recording/reproducing coils, and between each of the recording/reproducing coils and a load resistor connected to each of the recording/reproducing coils, A magnetic disk device characterized in that switching means are connected to each of the magnetic heads to maintain an open state while the magnetic head is not in a recording/reproducing state.