JPH04285731A - Optical head actuator - Google Patents

Abstract

PURPOSE:To supply an optical head actuator whose movement can be conducted rapidly and which has a simple constitution without any error due to heat- generation of the components, in the optical head actuator driving the optical head part reading out the information from a recording medium with light. CONSTITUTION:The optical head part and a magnet 26 are constituted in one body and an oscillation enable pressing means with a plate spring 27 for the movement in the first direction is provided and a sliding means provided a shaft 29 for the movement in the vertical direction to the first direction is provided. The pressing means is driven with a focusing coil 30 provided in the circumference of the optical head with this constitution and also the sliding means is driven with a tracking coil 31 provided in the circumference. Hence the heat generation does not occur in the optical head part and the stable optical head actuator is constituted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head actuator for an optical disk device that records and reproduces information signals using a rotationally driven information recording disk (hereinafter referred to as disk) as a medium.

0002

[Background Art] In recent years, optical disk devices have attracted attention as next-generation information recording devices that meet the needs of the information society.
It is gradually becoming popular. Therefore, efforts are being made to improve performance, reduce weight, and reduce cost. In particular, it is important to improve the area around the optical head, which can be said to be the heart of the system.

An example of the optical head actuator of the above-mentioned conventional optical disk device will be described below with reference to the drawings.

FIGS. 3 and 4 show a conventional optical head actuator, with FIG. 3 being a plan view and FIG.
FIG. 4(b) is a sectional view taken along line X-X' in FIG.

As shown in FIGS. 3 and 4, the components include a disk 1, which is rotationally driven by a motor 2. As shown in FIGS. Reference numeral 3 indicates an objective lens, and 4 indicates a reflecting mirror, which constitutes a so-called optical head section that focuses a light beam 6 emitted from an optical block 5 onto a disk 1 to record and reproduce information signals. A lens holder 7 holds the objective lens 3 and has a focusing coil 8 and a pair of tracking coils 9 on the side.
is installed. 10 is the shaft and yoke 1
1, into which a lens holder 7 is slidably and rotatably inserted. A pair of focusing magnets 12 and four tracking magnets 13 are attached to the yoke 11. The magnetization direction of the magnet is N in Figure 2(a).
This is the direction indicated by -S. 14 is a lead wire that supplies driving current to the focusing coil 8 and tracking coil 9 to generate driving force in the sliding direction (Z direction) and rotation direction (θ direction) on the lens holder 7 holding the objective lens 3. let 15 is a transfer base, which includes a reflector 4 and a yoke 11.
is attached, and a pair of transfer coils 16 are attached to both ends (hereinafter, this block will be referred to as a transfer block). Further, reference numeral 19 denotes a transfer shaft on which the transfer base 15 can slide. 17 is a transfer magnet, and 18 is a transfer yoke. By supplying a drive current to the transfer coil 16, a driving force in the transfer direction (X direction) is generated in the transfer base 15. Reference numeral 20 denotes a lead bundle which supplies driving current from a driving circuit 21 to each coil. 22 is a motor base. With the above configuration, the objective lens 3 can be moved to make the focal point of the light follow the undulations (surface runout) in the Z direction of the disk 1, and can also be moved to any position in the X direction of the disk 1 to adjust the undulations of the signal track. (eccentricity). The driving current is distributed so that the transfer coil 16 generates a driving force for coarse movement, and the tracking coil 9 generates a driving force for fine movement.

[0006]

[Problems to be Solved by the Invention] However, the above configuration has the following problems. 1. The weight of the transfer block is large, and the drive mechanism for transfer becomes large. 2. The transport system has many components and is complicated, and mechanical resonance is likely to occur and the position control of the objective lens is likely to be unstable. 3. Wiring of multiple coils is required within the transfer block, which complicates assembly. Further, since a large number of lead bundles are attached to the transfer block, a harmful load is generated during transfer. 4. An electromagnetic coil is placed close to the objective lens,
The objective lens may be deformed or altered due to the heat generated by the coil.

The present invention takes the above-mentioned problems into consideration and provides an optical head actuator that has a simple and lightweight transfer block, is easy to assemble, and has highly stable control operations.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the optical head actuator of the present invention includes a permanent magnet attached integrally with an optical head section consisting of an objective lens, a reflecting mirror, etc., and a permanent magnet attached to the objective lens. a biasing means capable of swinging in a first direction parallel to the focal direction of the biasing means; a support member supporting the biasing means; and a support member movable in a second direction perpendicular to the first direction. A sliding means for leveling the permanent magnet, and a configuration that generates driving forces in the first and second directions to the permanent magnet by energizing first and second electromagnetic coils that are arranged to face and be spaced apart from the permanent magnet. It is something that

[0009]

[Operation] In the present invention, since the permanent magnet integrated with the transfer block is magnetized with the above-described structure, the first electromagnetic coil generates a magnetic field parallel to the focal direction of the objective lens.
This causes the transfer block to swing due to the biasing means,
Since the second electromagnetic coil generates a magnetic field in a direction perpendicular to the magnetic field generated by the first electromagnetic coil, it becomes possible to transfer the transfer block by the sliding means in a direction perpendicular to the swinging by the biasing means. . Further, the transfer block has a simple structure consisting of an objective lens, a reflecting mirror, a permanent magnet, and a supporting member thereof, and there is no need for a lead wire attached to the transfer block.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical head actuator according to an embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an optical head actuator according to an embodiment of the present invention. FIG. 1 is a plan view, FIG. b) is a cross-sectional view taken along line X-X' in Figure 1, and Figure 2(c) is a cross-sectional view taken along line Z-Z in Figure 2(b).
'It is a sectional view.

As shown in FIGS. 1 and 2, its components are: 1 a disk, 2 a motor, 3 an objective lens,
4 is a reflecting mirror, 6 is a light beam, 23 is a motor base, and 24 is an optical block, and the above components are almost the same as those of the conventional example. Reference numeral 25 denotes a transfer holder, which corresponds to a so-called optical head part, and has an objective lens 3 and a reflecting mirror 4 fixed therein, and this is fixed with a support member, and four magnets 26 are attached to both ends of the support member. Fixed. The magnetization direction of the magnet is the direction indicated by N-S in FIG. 27 is a leaf spring, and 28 is a slider, which are integrally attached to the transfer holder 25. That is, as shown in FIG. 2(b),
Since it is held on the shaft 29 by the slider 28, the portion of the objective lens 3 located at the center thereof swings with the largest amplitude. Furthermore, a stopper (not shown) is provided to prevent the transfer holder 25 from shifting laterally. 29 is a shaft into which the slider 28 is slidably inserted. The leaf spring 27 has its longitudinal direction aligned with the axial direction of the shaft 29. As shown in FIG. 2(b), the slider 28 has a shaft contacting section with an R cross section, and is also slightly flexible, so that the radial load on the bearing when the transfer holder 25 moves up and down is reduced. Ru. With the above configuration, the transfer holder 25 can swing vertically and slide horizontally. 30 is a focusing coil which is a first electromagnetic coil, 31 is a pair of tracking coils which are second electromagnetic coils, and 32 is a yoke which is arranged to face the magnet 26 and to pass current through these coils. Since the generation of magnetic fields in two directions can be controlled freely, driving forces in two directions are generated in the transfer holder 25 in cooperation with the magnet 26. As a result, rocking is possible due to the spring force of the leaf spring 27 and the force due to the magnetic field, and movement in the other direction is guided by the shaft 29. Note that the transfer holder 25 is made of a magnetic material in order to improve the passage of the magnetic flux of the magnet 26. Drive circuit (not shown)
A focusing coil 30 and a tracking coil 31 are connected to the transfer block 25, and the transfer block including the transfer holder 25 does not need to be connected since it does not have a coil. With the above configuration, the transfer holder 25 including the objective lens 3, the so-called optical head section, can be driven to make the focus of light follow the waviness (surface wobbling) of the disk 1 in the Z direction. It is moved to an arbitrary position to follow the undulation (eccentricity) of the signal track.

As described above, according to this embodiment, there are two types: the transfer holder 25 to which the objective lens 3, the reflecting mirror 4, and the magnet 26 are integrally attached, the leaf spring 27, the slider 28, and the shaft 29. By providing the focusing coil 30 and tracking coil 31, which are electromagnetic coils, around the movable part equipped with the optical head section that outputs the laser, the movable part equipped with the optical head part that outputs the laser can be made smaller and simpler. Therefore, the influence of wire load and coil heat generation on the objective lens can be reduced.

[0014]

Effects of the Invention As is clear from the above description, the present invention includes a permanent magnet that is integrally attached to an objective lens and a reflecting mirror, and a permanent magnet that is oscillated in a first direction parallel to the focal direction of the objective lens. a supporting member for supporting the urging means; a sliding means for making the supporting member movable in a second direction orthogonal to the first direction; By providing two sets of electromagnetic coils arranged in parallel, it is possible to simplify and reduce the weight of the transfer block including the objective lens, and to realize an optical head actuator that is easy to assemble and has a highly stable control operation.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a head actuator according to an embodiment of the present invention.

[Fig. 2] (a) Y- of the head actuator of the same embodiment
Y' sectional view (b) XX' sectional view of the head actuator of the same embodiment (c) Z-Z' sectional view of the head actuator of the same embodiment

[Figure 3] Plan view of a conventional head actuator

[Figure 4]
(a) YY' sectional view of the conventional head actuator (b) XX' sectional view of the conventional head actuator

[Explanation of symbols]

3 Objective lens 4 Reflector 25 Transfer holder 26 Magnet 27 Leaf spring 28 Slider 29 Shaft 30 Focusing coil 31 Tracking coil 32 York

Claims (3)

[Claims] 1. An optical head unit that outputs a light beam, a support member that supports the optical head unit, a pair of permanent magnets attached to both ends of the support member, and a permanent magnet configured to move the support member in a first direction. a biasing means for swinging, a sliding means for moving the support member in a second direction perpendicular to the first direction, and a first electromagnetic coil wound around the support member; and a second electromagnetic coil wound separately on opposing legs of a magnetic material disposed around the support member, the magnetic field generated by the first electromagnetic coil causing the support member to An optical head actuator that is swung in a first direction by an urging means, and the support member is moved in a second direction by the sliding means by a magnetic field generated by the second electromagnetic coil. 2. The optical head actuator according to claim 1, wherein the support member includes a magnetic material that magnetically connects the pair of permanent magnets. 3. The optical head actuator according to claim 1, wherein the biasing means comprises a leaf spring that holds the head portion.