JPH06309607A - Magnetic field modulation overwrite system magnetic head - Google Patents

Abstract

PURPOSE:To suppress unnecessary power consumption and to prevent the deterioration of a magnetic head by forming the winding wire of a coil with a winding wire whose diameter is specified within + or -30% or below of the wire diameter where the power consumption of the magnetic head becomes minimum. CONSTITUTION:The magnetic head consists of a core 1 and a coil 2, and the core 1 is formed out of a ferrite material having a low electric conductivity in order to reduce loss by suppressing an eddy current caused by a transmission magnetic field. Further, round the coil 2, the winding wire whose diameter within + or -30% or below of the wire diameter where the power consumption of the magnetic head becomes minimum is wound in many numbers of winding of e.g. about 30-60 turns for reducing a driving current. Therefor, a multilayer winding wire structure is constituted by about four to six layers. Thus, the unnecessary power consumption is suppressed, and also heat generation is reduced to prevent the deterioration of the magnetic head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a magnetic head for recording used in a magneto-optical disk drive device, a hard disk device or the like of a magnetic field modulation overwrite type.

[0002]

2. Description of the Related Art In recent years, a magnetic field modulation overwrite technique has been developed which enables writing without erasing operation.

In the conventional magneto-optical disk drive, at the time of writing, a high-power laser beam emitted from an optical pickup is first radiated to a recording film of the magneto-optical disk in a state in which a direct current magnetic field is applied, and the recording film of the magneto-optical disk is temporarily erased. After erasing the data of, the high output laser light is turned on in the condition that the reverse DC magnetic field is applied.
Writing was performed by turning it off.

On the other hand, in the magnetic field modulation overwrite system,
The high-power laser beam emitted from the optical pickup heats the recording film of the magneto-optical disk, and at the same time, a magnetic field is applied at high speed by the magnetic head to write data. Therefore, there is a great advantage that the erasing operation becomes unnecessary, the data writing time can be shortened, and digital voice recording can be performed in real time.

The operation of the drive circuit of the magnetic field modulation overwrite type magnetic head (hereinafter referred to as the magnetic head) will be described below.

FIG. 4 is a circuit diagram of an example of the drive circuit. In the magnetic field modulation overwrite, it is necessary to reverse the magnetic field at a high speed as described above, and therefore, as shown in FIG. 4, field effect transistors (hereinafter referred to as transistors) Q _{1 to} Q ₄ are connected in H bridge and connected in series. A magnetic head having a configuration in which switches by diodes D ₁ and D ₂ are added between the transistors Q ₁ , Q ₃ and Q ₂ , Q ₄ , respectively, and a coil L of the magnetic head is connected between the transistors Q ₃ and Q _4. The drive circuit is, for example, Japanese Patent Laid-Open No. 1-1.
It is disclosed in Japanese Patent No. 30302.

Transistor Q₁, Q_FourAnd Transis
Q₂, Q₃The two sets of transistors are alternately
Is given a control signal to repeat ON and OFF
It That is, the transistor Q₁, Q_FourWhen is ON
Is the transistor Q₂, Q₃Off, transistor
Q₁, Q_FourIs off, transistor Q₂, Q
₃Turns on. Therefore, the current flowing through the coil L is
And, as a result, the magnetic field is also reversed. Also transistors
Q₁, Q_FourImmediately after turning from ON to OFF,
Due to the counter electromotive voltage generated by the coil L, the diode D₂of
Since a high voltage of several tens of volts is applied to the cathode,
De D₂Is turned off. This allows the transistor
Q₃, Q_FourAnd the loop of the coil L is formed. this
The loop consists of the inductance and resistance of the coil L and
Transistor Q₃And Q_FourCapacitance and
It forms an LCR resonance circuit consisting of on-resistance, etc.
The current is inverted with a time constant determined by the value of CR.

As described above, in the magnetic head drive circuit having this configuration, the resonance phenomenon of LCR at the time of current reversal is utilized, so that even if the magnetic head has a relatively large inductance, the values of C and R can be appropriately selected. Magnetic field reversal becomes possible at high speed.

In the magnetic field modulation overwrite method, as described above, high-speed current reversal is performed, and the recording frequency is as high as several hundred KHz to several MHz, so that the power loss in the magnetic head becomes large. For this reason, research has been conventionally conducted to reduce the power loss of the magnetic head.
For example, "magnetic head for magnetic field modulation magneto-optical recording" (The Institute of Electronics, Information and Communication Engineers, Magnetic Recording Research Group material, MR87-52).
13-20).

[0010]

By the way, the shape and material of the core of the magnetic head have been conventionally examined as shown in the above disclosure, but the winding diameter of the coil of the magnetic head has been studied. However, due to insufficient studies, the optimum winding diameter for low power consumption has not been clarified, and as a result, the winding diameter is inappropriate and power consumption has increased. Also in the above disclosure, only the case where the winding diameter is 40 μm or less (page 16) and the case where the winding diameter is 30 μm (page 18) are described.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems, to provide a recording magnetic head which consumes less power and suppresses heat generation of the magnetic head.

[0012]

In the magnetic field modulation overwrite type magnetic head of the present invention, the winding of the coil of the magnetic head is averaged in the recording signal band to be used and the power consumption of the magnetic head is minimized. The wire diameter is within ± 30% of the wire diameter.

[0013]

According to the present invention, the winding diameter is set to be near the minimum power consumption wire diameter determined by the recording frequency band, so that the power consumption can be reduced. Further, heat generation in the magnetic head is reduced, and deterioration of the magnetic head is suppressed.

[0014]

1 (a) is a plan view of a magnetic head according to an embodiment of the present invention, and FIG. 1 (b) is a sectional view taken along line AA '.

The magnetic head comprises a core 1 and a coil 2. The core 1 suppresses the eddy current generated by the transmission magnetic field and reduces the loss, so that the core 1 has a low conductivity (for example, 30
0 to 700 Ω · cm) made of ferrite material. Also,
The coil 2 has a large number of turns (for example, 30 to 60 turns) to reduce the drive current, and therefore 4 to 4 turns.
It has a multi-layer winding structure of about 6 layers. FIG. 1B shows the case of four layers.

FIG. 2 shows the wire diameter (50 μm, 60 μm, 90 μm) of the magnetic head shown in FIGS. 1 (a) and 1 (b).
m) and recording frequency (200 KHz to 1 MH)
It is a graph of the result of having measured power consumption by changing z).
As shown in FIG. 2, the power consumption is smaller when the wire diameter is thicker at low frequencies, and the power consumption is smaller when the wire diameter is thinner at high frequencies. Further, at the intermediate frequency, the magnetic head having the medium diameter has the lowest power consumption. In this way, the wire diameter that minimizes the power consumption varies depending on the recording frequency. Therefore, in order to suppress the power consumption, it is important to select the wire diameter according to the recording frequency so that the power consumption is averaged minimum in the recording signal band used.

FIG. 3 shows, as an example, an EFM (Eight Fourteen Modul) used in a compact disc (CD) or the like.
ation) signal (frequency band 200 KHz to 720 KH
7 is a graph of power consumption measurement results when z) is added to the magnetic head. In this case, it can be seen that the power consumption is lowest when the wire diameter is around 70 μm. Further, in the range of 50 to 85 μm, the difference in power consumption is about 20 mW, which is relatively small compared to 70 μm, but if it exceeds the range, the power consumption increases rapidly. Therefore, the wire diameter is centered around 70 μm ±
If it is within the range of about 30%, it can be used. Therefore,
The recording magnetic head of a rewritable CD device of the magnetic field modulation overwrite type using a magneto-optical disk has about 50
It is preferable to use a coil having a wire diameter of 85 μm.

It is assumed that there is a similar tendency when the recording signal band increases.

[0019]

As described above, according to the present invention, the wire diameter can be selected so that the power consumption in the magnetic head is minimized depending on the frequency band of the recording signal, so that unnecessary power consumption can be suppressed. At the same time, less heat is generated, and deterioration of the magnetic head can be prevented.

[Brief description of drawings]

1A is a plan view of a magnetic head according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA ′ of FIG.

FIG. 2 is a graph showing the relationship between frequency and power consumption according to wire diameter.

FIG. 3 is a graph showing a relationship between a coil wire diameter and power consumption in an EFM signal band.

FIG. 4 is a circuit diagram of an example of a drive circuit of a magnetic head.

[Explanation of symbols]

1 core 2 coil Q ₁ , Q ₂ , Q ₃ , Q ₄ transistor D ₁ , D ₂ diode

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kunio Kojima 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (2)

[Claims] 1. A core and a coil, wherein a winding of the coil has a wire diameter within ± 30% of a wire diameter at which the power consumption of the magnetic head is minimum on average in a recording signal band to be used. A magnetic field modulation overwrite type magnetic head comprising a winding. 2. The recording signal band used is from 200 KHz to
When the EFM signal is 720 KHz, the wire diameter of the winding is 50 ~
The magnetic field modulation overwrite type magnetic head according to claim 1, wherein the magnetic head has a thickness of 85 μm.