JPS61194603A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To extend a resonance frequency in a high frequency band so as to reduce a random noise and to obtain a magnetic disk excellent in an S/N characteristic by applying more than two coils to one magnetic converting element and providing a reproducing circuit used for amplifying signals from more than two recording and reproducing circuits with the aid of a differential. CONSTITUTION:The titled device is constituted with a magnetic head 3 wound by two bisected coils 6, two read/write amplifiers 2 and a read-only differential amplifier 4. The bisected coils 6 enable an inductance L and a coil resistance (r) to drop to one-fourth a conventional one and a half, respectively, and comprise two equivalent circuits. Thus two read/write amplifiers 2 are provided, and the read-only differential amplifier 4 compensates (amplifies) them. As a result the resonance frequency f0 in the equivalent circuit can double a conventional one.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic disk device, and particularly to a magnetic disk device suitable for high frequency recording.

[Background of the invention]

In the magnetic disk drives currently being developed, as the recording frequency becomes higher, it is required to increase the resonant frequency of the reproducing system including the magnetic head. To increase this resonance frequency, increase the inductance of the magnetic head or
Reducing stray capacitance in circuits and transmission lines becomes extremely important. However, in response to these demands, there are limits to reducing the capacity of the circuit system.

In addition, as a method for realizing high frequency recording by reducing the inductance of the magnetic head, for example,
As shown in Japanese Patent No. 623, a method is known in which the inductance of a magnetic head is lowered by reducing the cross-sectional area of the winding portion of the magnetic head.

However, with this method, the inductance of the magnetic head is lowered, and the electromagnetic conversion characteristics are also lowered at the same time, and the S/N characteristics are not improved much.

[Purpose of the invention]

The purpose of the present invention is to solve these conventional problems by changing the recording and reproducing circuit system and extending the resonant frequency of the reproducing system including the head to a high frequency range.

An object of the present invention is to provide a magnetic disk device that reduces random noise and has excellent S/N characteristics.

[Summary of the invention]

In order to achieve the above object, the present invention provides a magnetic disk device for recording and reproducing signals on a magnetic recording medium.
A magnetic head in which two or more windings are applied to one magnetic conversion element, and two or more recording/reproducing circuits for applying a recording current to the magnetic head or amplifying a signal from the magnetic head. and a reproducing circuit for differentially amplifying signals from the two or more recording/reproducing circuits.

[Embodiments of the invention]

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

FIG. 1 is a comparative diagram of the configuration of a recording and reproducing system of an embodiment of the present invention and a conventional magnetic disk device, and FIG. (b) shows a recording/reproducing system of a conventional magnetic disk device. The present embodiment will be described below while being compared with a conventional example.

In Fig. 1, 1 is a conventional magnetic head, 2 is a lead/
a write amplifier; 3 a magnetic head used in the magnetic desk device of the present invention; 4 a read differential amplifier; 5 a winding;
6 is a winding divided into two.

In the recording/reproducing system of a conventional magnetic disk device, a magnetic head 1 having a winding 5 is connected to a read/write amplifier 2, but in this embodiment, a winding 6 divided into two is connected. A magnetic head 3 with two windings and two leads/
It is composed of a write amplifier 2 and a read differential amplifier 4.

FIG. 2 is a diagram comparing the equivalent circuits of the magnetic head used in this embodiment shown in FIG. 1 and the conventional magnetic head.
Figure (a) shows the equivalent circuit of the magnetic head of this embodiment, and Figure 2 (b) shows the equivalent circuit of the magnetic head of this embodiment.
) indicate the equivalent opening and path of the conventional magnetic head.

The equivalent circuits of the conventional and this embodiment are composed of the inductance of the magnetic head, the stray capacitance C, and the winding resistance r, but because one winding 5 is divided into two, (
The winding 6) has an inductance of 1/45th of the conventional winding resistance r, which is reduced to 1/2 of the conventional winding resistance r. Since one winding is divided into two, FIG. 2(a) constitutes two equivalent circuits.

The resonant frequency fO in the equivalent circuit of FIG. 2(b) is determined by the inductance and stray capacitance C of the magnetic head, and can be obtained from the relationship fo = 1/2π (1/LC). The impedance characteristics of this magnetic head are shown in FIG. As can be seen from FIG. 3, the impedance tends to locally increase at the resonance frequency f. In current magnetic disk drives, an increase in impedance near this resonance point leads to a sudden increase in head noise, so this resonant frequency is kept out of the operating band, and frequencies above the operating band are electrically controlled. The commonly used method is to cut the

This method requires that the resonant frequency be higher than the operating band, so for magnetic disk drives that require high-frequency recording, an important issue is how to raise the resonant frequency of the recording and reproducing system. It's coming. In order to solve this problem, as described above, one winding is divided into two to increase the resonant frequency. Accordingly, two read/write amplifiers 2 are provided, and compensation (amplification) is performed by a read differential amplifier 4.

Therefore, the resonant frequency f in each equivalent circuit in FIG. 2(a) is f o = 1/2 tt (4/L
C), and the resonant frequency f can be doubled compared to the conventional one.

FIG. 4 is a diagram comparing the impedance characteristics of a magnetic head used in the present invention and a conventional magnetic head. Here, the broken line shows the conventional head, and the solid line shows the magnetic head of the present invention.

As can be seen from the relationship, by using the magnetic head of the present invention, it is possible to double the resonance frequency fo before the read/write amplifier 2 and reduce the impedance during resonance. As a result, the resonant frequency fo of the reproduction system including the head and amplifier can be easily increased, making it suitable for high-frequency recording magnetic disk drives.In addition, by lowering the impedance of the magnetic head,
Since head noise is reduced, a magnetic disk device with excellent S/N characteristics can be provided.

In this way, according to this embodiment, since recording and reproducing are performed using two recording/reproducing circuits (read/write amplifier 2) provided on the magnetic transducer, the reproducing system including the head The self-resonance frequency of the device can be approximately doubled compared to the conventional device. Furthermore, by dividing the winding into two parts and connecting them to the recording/reproducing circuit, head noise (random noise) can be reduced by about 70%. As a result, a magnetic disk device suitable for high frequency recording and having excellent S/N characteristics can be provided.

〔Effect of the invention〕

As explained above, according to the present invention, random noise is reduced by changing the method of the recording/reproducing circuit and extending the resonant frequency of the reproducing system including the head to a high frequency range.
A magnetic disk device with excellent /N characteristics can be realized.

[Brief explanation of the drawing]

FIG. 1 is a comparative diagram of the configuration of a recording and reproducing system of an embodiment of the present invention and a conventional magnetic disk device, and FIG. (b) is a diagram comparing the equivalent circuits of the magnetic heads of this embodiment and the conventional example, FIG. 3 is an impedance characteristic diagram of the magnetic head of FIG. 2(b), and FIG. 4 is a diagram of the magnetic head used in the present invention. FIG. 3 is a diagram comparing the impedance characteristics of a conventional magnetic head and a conventional magnetic head. ■=Conventional magnetic head, 2: Read/write amplifier,
3: magnetic head used in the magnetic disk device of the present invention, 4: differential amplifier for reading, 5: winding, 6: winding divided into two, L: inductance of magnetic head, C: stray capacitance, r: winding Line resistance Figure 1 Figure 2 (a) (k+) Figure 4 Frequency (MH2) Figure 3 - Frequency (MH2)

Claims (1)

[Claims] (1) In a magnetic disk device that records and reproduces signals on a magnetic recording medium, a magnetic head is provided with two or more windings on one magnetic transducer, and a recording current is applied to the magnetic head, or , comprising two or more recording and reproducing circuits for amplifying signals from the magnetic head, and a reproducing circuit for differentially amplifying signals from the two or more recording and reproducing circuits. magnetic disk device.