JP3363741B2 - Magneto-optical disk recording device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk recording apparatus, and more particularly, it is applied to, for example, a magnetic field modulation type magneto-optical disk drive and adjusts the position of an objective lens based on a tracking error signal output from an optical pickup. , A magneto-optical disk recording device.

[0002]

2. Description of the Related Art In this type of magneto-optical disk recording apparatus, in order to improve the transmission speed of recorded data,
It is necessary to reduce the core or coil inductance of the magnetic head to increase the magnetic field modulation speed. However, if the core of the magnetic head is made smaller, the range in which the desired magnetic field strength is obtained becomes narrower, and even if the positional deviation between the magnetic head and the objective lens is small, a situation in which data cannot be recorded occurs.

Therefore, Japanese Patent Application Laid-Open No. 8-63821 [G11B 11 /
[10], a tracking control system for adjusting the tracking of the magnetic head is independently provided on the magnetic head side to prevent the positional deviation between the magnetic head and the objective lens.

[0004]

However, such a conventional technique has a problem that the circuit configuration becomes complicated by the provision of an original tracking control system. Hence,
A main object of the present invention is to provide a magneto-optical disk recording device capable of preventing the positional deviation between the magnetic head and the objective lens with a simple circuit configuration.

[0005]

SUMMARY OF THE INVENTION The present invention is a magneto-optical disk recording apparatus that adjusts the position of an objective lens based on a tracking error signal output from an optical pickup, and detects a predetermined frequency component of the tracking error signal. A magneto-optical disk recording apparatus comprising: means and an adjusting means for adjusting the position of the magnetic head based on a predetermined frequency component.

[0006]

In the tracking error signal output from the optical pickup, the low frequency component below the rotational speed of the magneto-optical disk is detected by the filter. This low frequency component is given to the drive coil of the magnetic head, and the tracking of the magnetic head is adjusted by this. The objective lens is
While vibrating slightly with a width smaller than the track width, it vibrates greatly so as to draw a sine wave having an amplitude of the eccentric amount of the disk. Since the frequency of this sine wave is less than or equal to the rotation speed of the magneto-optical disk, the tracking of the magnetic head is adjusted based on the low frequency component included in the tracking error signal, so that the magnetic head does not cause a large displacement and the objective is Follow the lens.

[0007]

According to the present invention, the position of the magnetic head is adjusted based on the predetermined frequency component of the tracking error signal output from the optical pickup.
It is possible to prevent the positional deviation between the magnetic head and the objective lens with a simple circuit configuration. The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0008]

1 and 2, a magneto-optical disk drive 10 of this embodiment includes an angle 12 having an L-shaped cross section, and an optical pickup 1 at the other end of the angle 12.
4 is fitted. Above the optical pickup 14, an objective lens 16 and a drive coil 18 that horizontally displaces the objective lens 16 are provided. The optical pickup 14
The deviation of the laser beam from the center of the track formed on the magneto-optical disk 20 is detected by a so-called three-spot FM detection method, and a tracking error signal having a waveform as shown in FIG. 4A is output. The tracking servo circuit 22 supplies a current proportional to the tracking error signal to the drive coil 18. This allows the objective lens 16
Is horizontally displaced, and tracking is adjusted.

A short side of a holder 24 having an L-shaped cross section is fixed to the other end of the angle 12, and a magnet 26 is attached downward to one end of the holder 24. Further, the leaf springs 28a and 28a are sandwiched so as to sandwich the other end of the holder 24 in the width direction.
One end of b is fixed, and a holder 30 is provided between the other end of the leaf spring 28a and the other end of the leaf spring 28b. A drive coil 32 is mounted on the upper surface of the holder 30 so as to face the magnet 26, and a suspension 36 that supports the magnetic head 34 at the other end is mounted on the lower surface of the holder 30. Therefore, the magnetic head 34 faces the objective lens 16 via the magneto-optical disk 20, and the objective lens 16
Data is recorded on the magneto-optical disk 20 by applying a predetermined magnetic field on the spot irradiated by. By disposing the drive coil 32 facing the magnet 26, the magnet 26 and the drive coil 30 have the positional relationship shown in FIG. Further, the magnet 26 has an N polarity from the center in the longitudinal direction to one end, and has an S polarity from the center to the other end in the longitudinal direction.

The filter 38 extracts low frequency components below the rotational speed of the magneto-optical disk 20 from the tracking error signal. For this reason, the magnetic head drive circuit 40 is shown in FIG.
A low frequency signal having a sine wave as shown in (B) is input. The amplitude of this low frequency signal does not exceed the amount of eccentricity of the magneto-optical disk 20. The magnetic head drive circuit 40 supplies a current proportional to such a low frequency signal to the drive coil 30. Therefore, the drive coil 30, that is, the magnetic head 34
Is displaced in the radial direction of the magneto-optical disk 20 by the reaction with the magnet 26. That is, the magnetic head 34 is
The objective lens 16 is tracked based on the low frequency signal shown in FIG.

While the objective lens 16 is displaced based on the tracking error signal shown in FIG. 4A, the magnetic head 34 is displaced based on the low frequency signal shown in FIG. 4B. Is due to the following reasons.
That is, the objective lens 16 vibrates minutely with a width of about 1 μm so as not to deviate from the track, and vibrates greatly so as to draw a sine wave with an eccentric amount (about 70 μm) of the magneto-optical disk 20. The magnetic field generated by the magnetic head 34 has a width sufficient to cover the beam spot even if the beam spot deviates by about 1 μm due to the slight vibration of the objective lens 16.
When it is deviated by μm, the beam spot cannot be covered. For this reason, the magnetic head 34 is displaced based on the low frequency component equal to or lower than the rotation speed of the magneto-optical disk 20.

However, the magnetic head drive system including the leaf springs 28a and 28b, the holder 30, the drive coil 32, the suspension 36, and the magnetic head 34 and the objective lens 1 are provided.
The objective lens drive system including 6 and the drive coil 18 has a forced vibration model structure of a spring-mass system, and the frequency / amplitude response characteristic is a second-order lag system. That is, when the frequency of the alternating current flowing through the drive coil 18 or 32 is lower than the resonance frequency of each drive system,
The magnetic head 34 and the objective lens 16 respond to the AC current without delay in phase, but when the frequency of the AC current is higher than the resonance frequency, the magnetic head 34 and the objective lens 16 are 180 degrees with respect to the AC current. Respond late.

Therefore, as shown in FIG. 5, when both the resonance frequencies of the objective lens drive system and the magnetic head drive system are lower than the rotation speed of the magneto-optical disk 20 and the respective resonance frequencies do not coincide with each other, the frequencies are Band x
At, the magnetic head 34 and the objective lens 16 are displaced in opposite directions. Therefore, the frequency / amplitude response characteristics of the magnetic head drive system and the objective lens drive system must be determined in consideration of the respective resonance frequencies and the rotation speed of the magneto-optical disk 20.

Specifically, when the resonance frequency of the magnetic head drive system and the resonance frequency of the objective lens drive system are lower than the rotation speed of the magneto-optical disk 20, the resonance frequencies match each other as shown in FIG. Need to let. On the other hand, if both the resonance frequency of the magnetic head drive system and the resonance frequency of the objective lens drive system are higher than the rotation speed of the magneto-optical disk 20, it is not necessary to match the resonance frequencies with each other as shown in FIG. . This is because the magnetic head 34 is driven on the basis of a low frequency signal below the rotation speed of the magneto-optical disk 20, and the low frequency signal does not exceed the resonance frequency. 5 to 7, the curve a shows the frequency / amplitude response characteristic of the objective lens drive system, and the curve b shows the frequency / amplitude response characteristic of the magnetic head drive system.

According to this embodiment, since the magnetic head 34 is driven based on the low frequency component contained in the tracking error signal, the positional deviation between the objective lens 16 and the magnetic head 34 can be prevented with a simple circuit configuration. can do.

[Brief description of drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention.

FIG. 2 is a sectional view of the embodiment shown in FIG.

FIG. 3 is an illustrative view showing a positional relationship between a drive coil and a magnet.

FIG. 4A is a waveform diagram showing a tracking error signal, and FIG. 4B is a waveform diagram showing a low frequency signal.

FIG. 5 is a graph showing frequency / amplitude response characteristics of a magnetic head drive system and an objective lens drive system.

FIG. 6 is a graph showing frequency / amplitude response characteristics of a magnetic head drive system and an objective lens drive system.

FIG. 7 is a graph showing frequency / amplitude response characteristics of a magnetic head drive system and an objective lens drive system.

[Explanation of symbols]

10 ... Magneto-optical disk drive 14 ... Optical pickup 16 ... Objective lens 18, 32 ... Drive coil 22 ... Tracking servo circuit 34 ... Magnetic head 38 ... Filter 40 ... Magnetic head drive circuit

Claims (2)

(57) [Claims] 1. A magneto-optical disk recording apparatus for adjusting the position of an objective lens based on a tracking error signal output from an optical pickup, wherein a detecting means for detecting a predetermined frequency component of the tracking error signal, and the predetermined frequency component. Adjusting means for adjusting the position of the magnetic head based on, and the optical pickup includes an objective lens drive system having the objective lens and a first drive coil of the objective lens,
The adjusting means includes the magnetic head and a second portion of the magnetic head.
A magnetic head drive system having a drive coil, wherein a first resonance frequency of the objective lens drive system and a second resonance frequency of the magnetic head drive system match each other and are lower than the rotational speed. Magneto-optical disk recording device. 2. A magneto-optical disk recording apparatus which adjusts the position of an objective lens based on a tracking error signal output from an optical pickup, a detecting means for detecting a predetermined frequency component of the tracking error signal, and the predetermined frequency component. Adjusting means for adjusting the position of the magnetic head based on, and the optical pickup includes an objective lens drive system having the objective lens and a first drive coil of the objective lens,
The adjusting means includes the magnetic head and a second portion of the magnetic head.
A magneto-optical disk recording apparatus including a magnetic head drive system having a drive coil, wherein a first resonance frequency of the objective lens drive system and a second resonance frequency of the magnetic head drive system are higher than the rotational speed. .