JPH10198991A - Biaxial actuator for objective lens, and magneto-optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a high function and a high accuracy for dieling with the miniaturization of a magnetic field modulation head core for enhancing a transfer rate, and to prevent an objective lens from runaway out of the magnetic field intensity distribution of a head core, by regulating the movable range in the tracking direction of the objective lens within the magnetic field intensity distribution of the magnetic field modulation head. SOLUTION: This actuator has a regulation means 43 consisting of pins 44 vertical to the biaxial base 23 on the fixing side and oblonge holes 45, which are loosely engaged with the pins 44 and formed in the bobbin 25 on the movable side. Then, an objective lens 10 is prevented from runaway, for example, of not less than 100μm in the tracking direction of the lens by regulating the movable range S2 of tracking directions (a), (b) of the lens 10 of a biaxial actuator 11 in the small range of ±10∼30μm. Thus, the optical axis of a laser spot light is enabled to perform a correct tracking in the small range of ±30μm with respect to the center of the magnetic field intensity distribution of the magnetic field modulation head core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recording information on a magneto-optical disk by irradiating a laser beam to the magneto-optical disk by an objective lens of an optical pickup while modulating the magnetic field of the magneto-optical disk by a magnetic field modulation head. M to perform (write) and playback (read)
The present invention belongs to the technical field of a biaxial actuator of an objective lens most suitable for application to an O drive or the like, and a magneto-optical disk device equipped with the actuator.

[0002]

2. Description of the Related Art Conventionally, a magneto-optical disk drive uses a magneto-optical disk having a large diameter (eg, 130 mm).
There are two types, an O drive and an MD drive using a magneto-optical disk having a small diameter (eg, 84 mm or less). The MO drive 1 including the two-axis actuator for the objective lens is configured as shown in FIGS. That is, the MO drive is inserted into the cartridge holder 5 in the drive main body 4 with the magneto-optical disk 2 housed in the cartridge 3, pulled into the drive main body 4 by the cartridge holder 5, and 6 is loaded. By this disk loading, the magneto-optical disk 2 is horizontally magnetically chucked on the spindle 7 of the spindle motor 6 and the disk table 8 by the center core 2a, and the magneto-optical disk 2 is moved vertically in the cartridge 3. Ascended to an intermediate position.

On the other hand, an optical pickup including an objective lens 10, a two-axis actuator 11 for driving the objective lens 10 in a focus direction, and an optical block 12 for transmitting and receiving a laser beam to and from the objective lens 10 are provided inside a drive body 4. 13 and a magnetic field modulation head 14 are arranged. Inside the drive body 4, arrows a and b are guided by a pair of left and right guide shafts 16 along the radial direction of the magneto-optical disk 2 (the direction along the radiation from the center of the magneto-optical disk). And a pair of left and right voice circuits 18 for driving the carriage 17 in the directions of arrows a and b, and a pair of left and right magnetic circuits 19 forming a closed magnetic circuit by a yoke and a magnet. A linear motor 20 is provided.

The objective lens 10 of the optical pickup 13 is mounted on the carriage 17 by a biaxial actuator 11.
The optical block 12 is fixed at a fixed position in the drive main body 4. The magnetic field modulation head 14 is provided above the rear end 17a of the carriage 17.
Is mounted via a suspension 15, and the magnetic field modulation head 14 is arranged at a position above the objective lens 10 downward. A pair of left and right voice coils 18 of a linear motor 20 are mounted on both left and right sides of the carriage 17, and a pair of left and right magnetic circuits 19 are fixed at fixed positions in the drive main body 4. The carriage 1
7, a magnetic field modulation head 1 is provided on the side surface of the rear end portion 17a during loading and unloading of the magneto-optical disk 2.
A head lifting mechanism 21 for driving the head 4 up and down with respect to the magneto-optical disk 2 is attached.

The two-axis actuator 11 has a shaft sliding system shown in FIGS. 7 and 8, and a plate spring system shown in FIGS. 9 and 10. 7 and 8, the central axis 24 is vertically erected on the biaxial base 23, and the bobbin 25 to which the objective lens 10 is attached is focused on the central axis 24. Slidable in the axial direction (i.e., the directions of arrows c and d), and around the central axis 24 thereof, the arrows a and
A pair of focus coils 26 and a total of four tracking coils 27 are mounted on both sides of the outer periphery of the bobbin 25 in a circular arc shape. A magnetic circuit component comprising an arc-shaped magnet 28 and a yoke 29 is mounted thereon. The two-axis actuator 11 of the leaf spring type shown in FIGS. 9 and 10 has both sides of a bobbin base 30 fixed on a two-axis base 23 with screws or the like and a hobbin 25 to which the objective lens 10 is attached. A total of four parallel leaf springs 31
And the bobbin 25 in the focus direction (arrows c and d directions) and the tracking direction (arrows a and b).
Direction), and a rectangular focus coil 26 and a pair of L-shaped tracking coils 27 are fixed to the bobbin 25, and a magnet 28 mounted on the biaxial base 23 in the focus coil 26; York 29
And a yoke 29 fixed to the side surface of the bobbin 25. The magnetic circuit component is disposed on both sides of the focus coil 28 and the tracking coil 27.

As described above, when the magneto-optical disk 2 is loaded on the spindle motor 6,
Through the pair of upper and lower openings 3a formed in the cartridge 3, the objective lens 1
0 is approached, and the magnetic field modulation head 14 is set on the upper surface side. After the disk loading, the magneto-optical disk 2 is rotationally driven at high speed in the cartridge 3 by the spindle motor 6, and the carriage 17 is horizontally moved in the directions of the arrows a and b by the linear motor 20. The lens 10 and the magnetic field modulation head 14 are moved together in the directions of arrows a and b. And
The optical block 1 of the optical pickup 13 is modulated while the magnetic field of the magneto-optical disk 2 is modulated by the magnetic field modulation head 14.
The laser beam LB emitted from the optical disk 2 is irradiated on the magneto-optical disk 2 by the objective lens 10 to record and reproduce information on the magneto-optical disk 2.

In this MO disk drive 1,
Optical block 1 fixed in place in drive body 4
The laser beam LB emitted from the second laser diode 32 is collimated by a collimator lens 33 and a beam splitter 34.
Horizontally, and the laser beam LB is bent 90 ° in the horizontal direction by a folding mirror 35 installed outside the optical block 12 so that the laser beam LB is in a light transmitting hole 36 formed in the carriage 17. The rising mirror 37 is horizontally irradiated, the laser beam LB is bent 90 ° in the vertical direction by the rising mirror 37 and is irradiated on the objective lens 10, and the spot light of the laser beam LB is magneto-optically irradiated by the objective lens 10. The light is converged on the recording surface of the disk 2. Then, the reflected light of the laser beam LB reflected from the magneto-optical disk 2 is returned to the beam splitter 34 of the optical block 12 through the rising mirror 37 and the return mirror 35, and the multi-lens 3
The light is received by a reading optical sensor 39 and a monitoring photodiode 40 constituted by a phototransistor or the like through the reference numeral 8. However, laser diode 3
By directing the optical axis of No. 2 directly to the rising mirror 37,
The folding mirror 35 can be omitted.

In the conventional MO drive 1 of this type, by energizing the focus coil 26 of the biaxial actuator 11, the objective lens 10 is driven integrally with the bobbin 25 in the focus direction (the directions of arrows c and d). ,
The spot light of the laser beam LB converges on the recording surface of the magneto-optical disk 2, that is, focuses. When the tracking coil 27 is energized, the bobbin 25
With the objective lens 10 in the tracking direction (arrows a,
b) to track the optical axis F of the spot light of the laser beam LB.

[0009]

By the way, this kind of MO
In a magneto-optical disk device such as the drive 1 which records information on the magneto-optical disk 2 by a magnetic field modulation method, in order to improve the recording density and achieve a high transfer rate, the rotation speed of the magneto-optical disk 2 is increased. In order to achieve high-speed response and low power consumption,
It is necessary to reduce the size of the head core of No. 4. And FIG.
As shown in FIG. 5, during recording, the center MC of the magnetic field intensity distribution existing in the head core of the magnetic field modulation head 14 and the spot light of the laser beam LB radiated from the objective lens 10 and converged on the recording surface of the magneto-optical disk 2 Is desirably made to coincide with the optical axis F on the recording surface. However, when the size of the head core of the magnetic field modulation head 14 becomes smaller, the range of the magnetic field intensity distribution existing in the head core also becomes smaller.
It is necessary to restrict the movable range of the spot light in the tracking direction to an extremely small range.

However, the conventional two-axis actuator 11
Is that the movable range S _{1 of the} objective lens 10 in the tracking direction is several tens in both the shaft sliding method and the leaf spring method.
Since it is as large as 0 μm or more, the conventional two-axis actuator 11 cannot cope with the miniaturization of the head core of the magnetic field modulation head 14, and its spot light is out of the range of the magnetic field intensity distribution of the head core, and Disc 2
There was a danger that the information recorded in the computer would be destroyed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide a two-axis actuator of an objective lens corresponding to a reduction in the size of a head core of a magnetic field modulation head.

[0012]

According to the present invention, there is provided a biaxial actuator for an objective lens for controlling the movable range of the objective lens in a tracking direction within a magnetic field intensity distribution of a magnetic field modulation head. Is provided.

In the biaxial actuator of the objective lens according to the present invention, the movable range of the objective lens in the tracking direction can be restricted within the magnetic field intensity distribution of the magnetic field modulation head by the restriction means.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a biaxial actuator of an objective lens in which the present invention is applied to an MO drive will be described below with reference to FIGS. The same components as those in FIGS. 3 to 10 are denoted by the same reference numerals, and the description will not be repeated.

That is, the two-axis actuator 11 of the present invention
Is in any case of the leaf spring system shown in axial sliding type and 2 shown in FIG. 1, the micro range of about ± 10 [mu] m the movable range S ₂ in the tracking direction of the objective lens 10 (arrow a, b directions) This is provided with a regulating means 43 for regulating the pressure. The restricting means 43 includes, for example, a pin 44 vertically erected on the biaxial base 23 on the fixed side,
It can be formed by a simple structure including a long hole 45 formed on the bobbin 25 on the movable side and loosely fitted to the pin 44. At this time, in the two-axis actuator 11 of the shaft sliding type shown in FIG. 1, the long hole 45 is formed in an arc shape centering on the pin 44. As shown by the solid line and the one-dot chain line in FIG. 1, the pin 44 and the elongated hole 45 are located at the position opposite to the objective lens 10 or on the objective lens 10 side with respect to the center pin 24, and other positions. , Center pin 2
4 may be provided at any position. In the plate spring type biaxial actuator 11 shown in FIG. 2, the long hole 45 is formed in a straight line parallel to the tracking direction (the directions of arrows a and b). In each of the two-axis actuators 11 of the shaft sliding type and the leaf spring type, the pin 44 is attached to the bobbin 25 which is the movable side, and the long hole 45 is the fixed side.
It may be formed on the shaft base 23.

According to the MO drive 1 having the biaxial actuator 11 of the present invention configured as described above, the objective lens of the biaxial actuator 11 can be controlled by the simple regulating means 43 including the pin 44 and the elongated hole 45. The movable range S ₂ in the tracking direction (arrows a and b) of 10 is ± 10
When the objective lens 10 is regulated in a very small range of about 30 μm,
Since runaway as described above can be prevented beforehand, the optical axis F of the spot light of the laser beam LB shown in FIG.
Accurate tracking can be performed only within a very small range of ± 30 μm with respect to C. Therefore, since the head core of the magnetic field modulation head 14 is downsized, the spot light of the laser beam LB goes out of the range of the magnetic field intensity distribution of the head core, and the information recorded on the magneto-optical disk 2 is destroyed. Danger can be avoided reliably.

The embodiments of the two-axis actuator of the objective lens and the magneto-optical disk drive according to the present invention have been described above. However, the present invention is not limited to the above-described embodiments, but is based on the technical idea of the present invention. Various changes can be made based on this.

[0018]

The biaxial actuator of the objective lens and the magneto-optical disk drive according to the present invention having the above-described structure have the following effects.

In the biaxial actuator for the objective lens according to the first aspect, the movable range of the objective lens in the tracking direction can be restricted within the magnetic field intensity distribution of the magnetic field modulation head by the restricting means, so that the recording density is improved. It is possible to realize a high-performance, high-precision magneto-optical disk device corresponding to the miniaturization of the head core of the magnetic field modulation head for reducing power consumption and improving the transfer rate, and the objective lens has the magnetic field of the head core of the magnetic field modulation head. The danger that the recorded information is destroyed due to runaway out of the intensity distribution can also be avoided.

The two-axis actuator of the objective lens according to the second and third aspects of the present invention provides the objective lens with a movable range in the tracking direction of the magnetic field modulation head in the tracking direction in any of the axial sliding type and the leaf spring type. Can be regulated within.

According to the biaxial actuator of the objective lens of the present invention, the movable range in the tracking direction of the objective lens can be restricted within the magnetic field intensity distribution of the magnetic field modulation head by a simple structure including a pin and a long hole. It is possible to realize a compact two-axis actuator which is simple in structure and manufacturing, low in cost, and compact.

In the magneto-optical disk drive according to the fifth aspect, the two-axis actuator of the objective lens and the magnetic field modulation head are integrally moved in the tracking direction by the carriage, so that the recording density is improved by downsizing the head core of the magnetic field modulation head. , Low power consumption and improvement of the transfer rate can be realized.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a shaft sliding method of a biaxial actuator of an objective lens in an MO drive to which the present invention is applied.

FIG. 2 is a plan view illustrating a leaf spring system of the biaxial actuator according to the first embodiment.

FIG. 3 is a partially cutaway plan view illustrating an MO drive equipped with a conventional two-axis actuator.

FIG. 4 is a sectional side view of FIG. 3;

FIG. 5 is an exploded perspective view illustrating a carriage and a magnetic field modulation head in the MO drive according to the first embodiment.

FIG. 6 is a cross-sectional side view illustrating a conventional two-axis actuator and a magnetic field modulation head.

FIG. 7 is a perspective view illustrating a conventional two-axis actuator of a shaft sliding type.

FIG. 8 is a plan view of FIG. 7;

FIG. 9 is a perspective view illustrating a conventional leaf spring type biaxial actuator.

FIG. 10 is a plan view of FIG. 9;

[Explanation of symbols]

1 is an MO drive which is a magneto-optical disk device, 2 is a magneto-optical disk, 10 is an objective lens, 11 is a biaxial actuator, 13 is an optical pickup, 14 is a magnetic field modulation head, 23 is a biaxial base, 24 is a central axis, 25 is a bobbin,
28 is a focus coil, 27 is a tracking coil,
28 is a magnet, 29 is a yoke, 30 is a bobbin base, 31 is a parallel leaf spring, 43 is regulating means, 44 is a pin,
45 is a long hole.

Claims (5)

[Claims] 1. A biaxial actuator for an objective lens, comprising: a restricting means for restricting a movable range of the objective lens in a tracking direction within a magnetic field intensity distribution of the magnetic field modulation head. 2. The apparatus according to claim 1, wherein the bobbin holding the objective lens is movable in a focus direction along a central axis and in a tracking direction around the central axis.
A two-axis actuator for the objective lens described. 3. The actuator according to claim 1, wherein said objective lens is supported by a parallel leaf spring or a parallel wire so as to be movable in a focus direction and a tracking direction. 4. The control means according to claim 1, wherein said restricting means comprises a pin and an elongated hole.
A two-axis actuator for the objective lens described. 5. A light comprising a carriage for integrally moving the biaxial actuator of the objective lens and the magnetic field modulation head in the tracking direction according to claim 1, 2, 3 or 4. Magnetic disk drive.