JP2003303432A - Optical pickup actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct inclination of the optical axis at high speed with a low electric consumption without twisting a suspension wire. <P>SOLUTION: The optical pickup actuator is equipped with a damper base (suspension wire supporting part) (22A) for the purpose of supporting the movable section including a lens holder (12A) for holding an objective lens (11), through a plurality of suspension wires (341-344), so as to make the section displaceable in the focusing direction (F) and the tracking direction (Tr), and also equipped with an actuator base (21A) for rockably supporting this damper base. In this optical pickup actuator, tilt driving devices (41, 46, 47) drive the damper base, relative to the actuator base, in the tilting direction around the rocking axis that extends in a prescribed direction (S) orthogonally crossing both the focusing direction (F) and the tracking direction (Tr). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup provided in an optical disk drive, and more particularly to an optical pickup actuator for displacing an objective lens in a vertical direction (focusing direction) and a horizontal direction (tracking direction).

[0002]

2. Description of the Related Art Recently, an optical disk drive is often mounted on an electronic device such as a personal computer. As a recording medium that can be used for optical disk drive,
CD-R (compact disc-recordable), CD-RW (c
ompact disc-rewritable) is known. The CD-R is a recordable recording medium, and the CD-RW is a rewritable recording medium.
Compatible with D (CD-DA). CD-R, CD-R
Writing to W requires a dedicated device and writing application, but reading from CD-R and CD-RW can be performed by a normal CD-ROM drive. CD-
R, CD-RW, CD-ROM, and audio C
D, DVD-ROM, DVD-R, DVD-R
AM, DVD + RW, DVD-RW, etc. are collectively referred to as an optical disc here.

Now, in order to write information (data) to and read information (data) from such an optical disc, an optical disc drive has an optical pickup for recording and reproducing for irradiating a laser beam on the optical disc. I have it.

In general, this type of optical pickup includes a laser light source for emitting a laser beam and an optical system for guiding the emitted laser beam to an optical disc. As described above, the CD-R can write information as well as read information. In the optical pickup for CD-R, it is necessary to switch the output of the laser beam emitted from the laser light source between the reading of information and the writing of information. The reason is that the writing of information is
This is because it is performed by forming pits in the recording layer of the optical disc by laser beam irradiation, and the output of the laser beam emitted from the laser light source during information writing is larger than the output during information reading, for example, 1
It is about 0 to 20 times.

In such an optical pickup, a laser beam emitted from the laser light source passes through an optical system, and is condensed on a signal recording surface of an optical disc by an objective lens which constitutes the optical system. Recording (writing) and erasing. On the other hand, the optical pickup reproduces information by detecting the reflected light (return light) from the signal recording surface by a photodetector (photodetector) which is a photodetector.

As described above, in the optical disc drive, the laser beam emitted from the optical pickup is used to record / reproduce the optical disc. Therefore, focusing control and tracking control are indispensable. In order to perform the focusing control and the tracking control, the optical pickup includes an optical pickup actuator for displacing the objective lens in the vertical direction (focusing direction) and the horizontal direction (tracking direction).

The conventional optical pickup actuator is
It has a movable part including a lens holder for holding an objective lens, a damper base for movably supporting the movable part vertically and horizontally via a plurality of suspension wires, and an actuator base for fixedly supporting the damper base. .

A conventional optical pickup actuator will be described below with reference to FIG. FIG. 1 is a perspective view of an optical pickup actuator.

The illustrated optical pickup actuator is
Movable part 1 forming part of an optical head (optical pickup)
0 and the movable part 10 in the vertical direction (focus direction) F
And a fixed portion 20 movably supported in the left-right direction (tracking direction) Tr, and a drive device 30 provided in these.
It has and.

The movable portion 10 comprises an objective lens 11, a lens holder 12 for holding the objective lens 11, and a holding portion 13 for integrally holding and holding the lens holder 12. The holding portion 13 has a hole 13a at the center. The drive device 30 is provided in the hole 13a. The drive unit 30 is divided into a movable part and a fixed part.

The movable portion of the driving device 30 has first and second tracking coils 31 and 32, and a focus coil 33. The first and second tracking coils 31 and 32 are held by a holding unit 13, are respectively wound in a vertical direction, and are provided symmetrically with respect to the central axis of the holding unit 13. On the other hand, the focus coil 33 is held by the holding unit 13 adjacent to the first and second tracking coils 31 and 32 in the central axis direction, and is wound in the horizontal direction. The fixed portion of the drive unit 30 will be described later.

In addition, first and fourth suspension wires 341, 342, 343, and 344, which are made of elastic rods or wire rods, are provided on each side of the holding portion 13.
Is provided. One ends 341a to 344a of the first to fourth suspension wires 341 to 344 are respectively attached to the holding portion 13 and the first to fourth projections 131, 132, 133 and 134 protruding outward in the horizontal direction from the holding portion 13.
It is fixed at. On the other hand, the other ends 341b to 344b of the first to fourth suspension wires 341 to 344 are
As will be described later, it is fixed to the damper base that constitutes the fixing portion 20.

The fixed portion 20 includes an actuator base 21.
And a damper base 22. The actuator base 21 is in the shape of a rectangular frame made of a magnetic metal material, and has a support block 211 that forms a receiving portion 21 a of the damper base 22 at one end thereof. That is, the damper base 22 is the support block 211.
It is fixedly supported on. The support block 211 is formed integrally with the actuator base 21.

The fixed portion of the driving portion 30 provided in the hole portion 13a of the holding portion 13 includes the first and second yokes 36 and 37 and the first and second magnets 38 and 3.
9 and. First and second yokes 36 and 37
Is composed of a part of the actuator base 21,
Stand up from the actuator base 21, and between them,
The first and second tracking coils 31 and 32 and the focus coil 33 described above are arranged. The first magnet 38 is the first tracking coil 31.
It is attached to the surface of the first yoke 36 on the side opposite to and 32. The second magnet 39 is attached to the surface of the second yoke 37 on the side facing the focus coil 33. The first yoke 36 and the first magnet 38 form a first fixed magnet portion, and the second yoke 37 and the second magnet 39 form a second fixed magnet portion.

That is, the drive device 30 includes the first and second tracking coils 31 and 32 held by the movable portion 10.
And a focus coil 33, and first and second yokes 36 and 37 and first and second magnets 38 and 39 provided on the fixed portion 20. The movable unit 10 is configured to be movable in the focus direction F and the tracking direction Tr with respect to the fixed unit 20 (actuator base 21) by the drive device 30.

In the drive unit 30, when the first and second tracking coils 31 and 32 and the focus coil 33 are energized via the first to fourth suspension wires 341 to 344, the first and second fixed magnets. The movable part 10 is fixed to the fixed part 20 by the action of magnetic flux from the part.
It is driven so as to move relative to the (actuator base 21), and the focus and tracking are adjusted.

[0017]

In the conventional optical pickup actuator as described above, when the objective lens 11 is moved in the focus direction F and the tracking direction Tr, the objective lens 11 moves with respect to the optical axis of the laser light. It is moved up and down and left and right so that it does not tilt.
The reason is that it is presumed that the signal recording surface of the optical disk arranged to face the objective lens 11 will generally have a substantially horizontal surface. In other words, the conventional optical pickup actuator is manufactured on the assumption that the signal recording surface of the optical disc has a horizontal surface.

However, an actual (actual) optical disk usually has a warp. Therefore, when an optical pickup equipped with a conventional optical pickup actuator is used to read a signal from an optical disc having such a warp or write a signal to the optical disc, at the laser light irradiation position of the optical disc, The optical disc and the objective lens are not parallel to each other. That is, the shape of the laser spot on the signal recording surface of the optical disc is deformed from the desired shape, and the shape of the laser spot is deteriorated. As a result, there is a problem that a read error or a write error occurs. In other words, the signal deterioration is caused due to the deviation between the signal recording surface of the optical disc and the optical axis of the laser light (objective lens) irradiated on the signal recording surface.

To solve this problem, the objective lens is tilted in order to correct the wavefront aberration generated by the tilt of the laser beam with respect to the signal recording surface due to the warp of the optical disk, or the signal recording surface of the warped optical disk is corrected. On the other hand, it is necessary to tilt the entire optical pickup in order to irradiate the laser beam vertically. That is, it is necessary to correct the inclination of the optical axis of the laser beam that is obliquely emitted in response to the change in the warp amount of the rotating optical disc. In order to deal with this problem, conventionally, the following three methods have been adopted.

The first conventional method is to dispose a tilt correction coil in the lens holder 12 that holds the objective lens 11 and tilt the lens holder 12 in accordance with the amount of warp of the optical disk.

The second conventional method is a method in which the slide shaft of the sled mechanism that slides the optical pickup itself along the radial direction of the optical disc is tilted in accordance with the amount of warpage of the optical disc.

The third conventional method is a method of tilting the entire sled mechanism in accordance with the warp amount of the optical disk.

However, each of the first to third conventional methods has the following problems.

In the first conventional method, when the lens holder 12 of the objective lens 11 is tilted, the suspension wire 34
1 to 344 are twisted. In other words, the suspension wires 341 to 344 are stressed. When focus servo or tracking servo is applied to the optical pickup actuator in a state where the suspension wires 341 to 344 are twisted, a new resonance that normally cannot occur occurs in the objective lens 11. As a result, the characteristics of the focus servo and the tracking servo deteriorate.

On the other hand, the second or third conventional method requires a mechanism for driving the slide shaft or the sled mechanism as a whole (hereinafter referred to as "tilt drive mechanism"). Since the weight of the driven body (slide shaft or sled mechanism as a whole) driven by the tilt drive mechanism is heavy, power consumption in the tilt drive mechanism becomes high in order to correct the tilt of the optical axis at high speed.

Therefore, it is an object of the present invention to provide an optical pickup actuator capable of correcting the inclination of the optical axis at high speed without twisting the suspension wire.

Another object of the present invention is to provide an optical pickup actuator which has low power consumption and is capable of correcting the inclination of the optical axis at high speed.

[0028]

According to the present invention, a movable part (10A) including a lens holder (12A) for holding an objective lens (11), and a plurality of movable parts (10A) extending from both sides thereof. A damper base (2) for movably supporting the suspension wire (341 to 344) in the focus direction (F) and the tracking direction (Tr).
2A), an actuator base (21A) that swingably supports the damper base, and main drive devices (31-1 to 31-4, 33, 31) that drive the movable portion with respect to the actuator base in the focus direction and the tracking direction. Three
6, 37, 38), and a tilt drive device for driving the damper base with respect to the actuator base in a tilt direction around a swing axis extending in a predetermined direction (S) orthogonal to both the focus direction and the tracking direction. (41,4
6 and 47) are obtained.

In the above optical pickup actuator, the swing axis is an optical axis which extends in the focus direction and passes through the center of the objective lens in a state where the movable portion is not driven in the focus direction and the tracking direction. So that it intersects at right angles to both the tracking axis which is orthogonal to and extends in the tracking direction and passes through the center of the objective lens.
It is preferably arranged. In addition, the tilt drive device includes, for example, a tilt coil (41) horizontally wound and held on a damper base, and a pair of tilt magnets (46, 46) provided on the actuator base so as to face the tilt coil. 47) and The main drive device includes, for example, a tracking coil (31-1 to 31-4) and a focus coil (33) held by a movable part, a yoke (36, 37) and a magnet (38, 37) provided on an actuator base. Three
9) and may be comprised.

It should be noted that the reference numerals in the above parentheses are given for facilitating understanding and are merely examples, and needless to say, are not limited to these.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

An optical pickup actuator according to an embodiment of the present invention will be described with reference to FIGS. 2 to 4. FIG. 2 is a perspective view of the optical pickup actuator. FIG. 3 is an exploded perspective view of the optical pickup actuator shown in FIG. FIG. 4 is a perspective view showing a state in which the optical pickup actuator shown in FIG. 2 is covered with a cover. 2 to 4, components having the same functions as those of the optical pickup actuator shown in FIG. 1 are designated by the same reference numerals. However, the conventional optical pickup actuator shown in FIG. 1 is a type in which the driving device 30 is provided only on one side of the objective lens 11, but the optical pickup actuator shown in FIGS. 2 to 4 will be described later. In addition, the main driving device 30A is provided on both sides of the objective lens 11.

The illustrated optical pickup actuator is
Movable part 1 forming part of an optical head (optical pickup)
0A, an up-down direction (focus direction) F and a left-right direction (tracking) T of which the optical axis extends through the movable portion 10A.
Support fixing portion 20A movably supported on r, main driving device 30A and tilt driving device 40 provided on these parts.
It has and.

The movable portion 10A includes an objective lens 11, a lens holder 12A for holding the objective lens 11, and a holding portion 13A for integrally holding and holding the lens holder 12A.
It has and. Main drive device 30A is divided into a movable part and a fixed part.

The movable portion of the main drive unit 30A has first to fourth tracking coils 31-1 to 31-4 and a focus coil 33. The first to fourth tracking coils 31-1 to 31-4 are held on both front and rear sides of the four corners of the holding portion 13A and are wound in the vertical direction,
It is provided symmetrically with respect to the central axis of the holding portion 13A. On the other hand, the focus coil 33 is held by the holding portion 13A adjacent to the first to fourth tracking coils 31-1 to 31-4 in the central axis direction and wound in the horizontal direction. The fixed portion of the main drive device 30A will be described later.

Further, on the left and right sides of the holding portion 13A, the first to fourth portions made of elastic rods or wire rods, two rods at the top and bottom, respectively.
Suspension wires 341, 342, 343 and 344 are provided. One ends 341a to 344a of the first to fourth suspension wires 341 to 344 are
Each of the first to fourth protrusions 131 to 134 (however, the third to third protrusions) protruding outward in the horizontal direction from the holding portion 13A, respectively.
(Not shown) is fixed. On the other hand, the other ends 34 of the first to fourth suspension wires 341 to 344
1b to 344b are supported by a damper base that constitutes a support fixing portion 20A described later.

The supporting and fixing portion 20A has an actuator base 21A and a damper base 22A. The actuator base 21A has the shape of a rectangular frame formed of a magnetic metal material, and has a support block 211 that forms a receiving portion of the damper base 22A at one end thereof.
Have. The damper base 22A is swingably supported on the support block 211, as described later. The support block 211 is formed integrally with the actuator base 21A.

The fixed portions of the main drive unit 30A provided on both front and rear sides of the holding portion 13A are the first and second yokes 3.
6 and 37, and first and second magnets 38 and 39. The first and second yokes 36 and 37 are made up of a part of the actuator base 21A and stand upright from the actuator base 21A, and between them, the first to fourth tracking coils 3 described above are provided.
1-1 to 31-4 and the focus coil 33 are arranged. The first magnet 38 is attached to the surface of the first yoke 36 on the side facing the first and second tracking coils 31-1 and 31-2, and the second magnet 39 is the third and third magnets. 4 tracking coils 3
The second yoke 3 on the side facing 1-3 and 31-4
It is attached to surface 7. First yoke 36 and first
And the second magnet 38 to form a first fixed magnet portion,
The second yoke 37 and the second magnet 39 form a second fixed magnet portion.

That is, the main drive unit 30A includes the movable portion 1
First to fourth tracking coils 3 held at 0 A
1-1 to 31-4, the focus coil 33, the first and second yokes 36 and 37, and the first and second magnets 38 and 39 provided on the fixed portion 20A.
It is composed of and. The movable portion 10A is configured to be movable in the focus direction F and the tracking direction Tr with respect to the fixed portion 20A (actuator base 21A) by the main drive device 30A.

In this main drive unit 30A, the first to fourth
When the first to fourth tracking coils 31-1 to 31-4 and the focus coil 33 are energized via the suspension wires 341 to 344, the movable parts are moved by the action of the magnetic flux from the first and second fixed magnet parts. 10A is driven so as to move relative to the fixed portion 20A (actuator base 21A), and focus and tracking are adjusted.

Next, the tilt drive device 40 will be described. Since the damper base 22A supports the first to fourth suspension wires 341 to 344 as described above, it is also called a suspension wire support portion. As will be described later, the damper base 22A is supported by the actuator base 21A so as to be swingable around a swing shaft. Here, the direction S in which the swing axis extends is a direction orthogonal to both the focus direction F and the tracking direction Tr. Therefore, the lens holder 12A holding the objective lens 11 is driven in the tilt direction around the swing shaft extending in the predetermined direction S together with the first to fourth suspension wires 341 to 344.

In the illustrated example, the swing axis passes through the center of the objective lens 11 and the optical axis (focus axis) extending in the focus direction, and passes through the center of the objective lens 11 and is orthogonal to this optical axis. It is orthogonal to both the tracking axis extending in the tracking direction Tr.

As shown in FIG. 3, the actuator base 21A includes a pair of V-shaped support pieces 212 for supporting the damper base 22A so as to be swingable in a tilt direction around a predetermined direction S, and a damper base 21A. 22A has a pair of screws 213 for restricting the swing range. The pair of support pieces 212 are protrusions 212a (only one of which is shown in FIG. 3) protruding from the surfaces facing each other on the swing shaft.
have.

On the other hand, the damper base 22A has a pair of V grooves 222 (only one is shown) supported by a pair of support pieces 212, and a pair of through holes 223 through which a pair of screws 213 are penetrated. The protrusion 21 is formed in the pair of V grooves 222.
A hole (not shown) into which 2a is pivotally supported is formed. That is, the protrusion 212a formed in the pair of support pieces 212 and the hole formed in the V groove 222 form a swing shaft that swings the damper base 22A.

The tilt driving device 40 is divided into a driving portion and a fixed portion. The movable portion of the tilt drive device 40 has a tilt coil 41. This tilt coil 41
Is horizontally wound around the damper base 22A. The fixed portion of the tilt drive device 40 includes the first and second
Tilt magnets 46 and 47. The first and second tilt magnets 46 and 47 are attached to the support block 211 on the side facing the tilt coil 41.

That is, the tilt driving device 40 is composed of a tilt coil 41 held by the damper base 22A and first and second tilt magnets 46 and 47 provided on the actuator base 21A. By this tilt drive device 40, the damper base 22A (hence, the first to fourth suspension wires 341 to 341 to
44 and movable part 10A) are the actuator base 2
It is configured to be swingable in a tilt direction around the swing axis with respect to 1A.

As described above, in the tilt drive device 40 according to the present embodiment, the damper base 22A and the first to fourth suspension wires 341 to 341 are supported in a state where the damper base 22A is swingably supported by the actuator base 21A.
Since 344 and the movable portion 10A are driven around the swing axis in the tilt direction, the first to fourth suspension wires 341 to 344 are not twisted even when the lens holder 12A is tilted. Therefore, new resonance of the objective lens 11 does not occur.

On the other hand, in the tilt driving device for realizing the above-mentioned first conventional method, only the movable portion 10 is driven in the tilt direction with the damper base 22 fixedly installed on the actuator base 21. Therefore, when the lens holder 12 is tilted, the first to fourth suspension wires 341 to 344 are always twisted. As a result, as described above, stress is applied to the first to fourth suspension wires 341 to 344, and the objective lens 1
1 causes a new resonance that normally cannot occur.

In Japanese Patent Laid-Open No. 2001-319353, the movable portion is arranged so that the optical axis direction of the objective lens is substantially orthogonal to the signal recording surface of the optical disc in response to the change in focus height due to the warp of the optical disc. Discloses the technical idea of driving in the focus direction with a predetermined inclination. However, also in this publication, the damper base that supports the movable portion via the suspension wire is fixedly installed on the actuator base. Therefore, it is understood that the method according to this publication is substantially the same as the above-mentioned first conventional method. Therefore, even in the technique disclosed in this publication, when the lens holder is tilted, the suspension wire is twisted, which causes the same problem as in the first conventional method.

Further, since the tilt drive device 40 according to the present embodiment drives the damper base 22A, the first to fourth suspension wires 341 to 344, and the movable portion 10A as the driven bodies, it is the above-mentioned first. 2 or 3
Like the tilt drive mechanism to realize the conventional method of
The weight of the driven body becomes relatively light as compared with the case of driving a relatively heavy driven body such as the slide shaft or the entire sled mechanism. Therefore, the tilt drive device 40 according to the present embodiment can correct the tilt of the optical axis at high speed with low power consumption.

Further, in this embodiment, since the swing axis of the damper base 22A extends in the direction passing through the center of the objective lens 11, the center position deviation of the objective lens 11 is corrected when the optical axis is corrected. It is possible to prevent.

The present invention is not limited to the above embodiment,
Of course, various changes and modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, only an example applied to an optical pickup actuator of the type in which the main driving device is provided on both sides of the objective lens has been described, but the present invention is directed to only one side of the objective lens. It is needless to say that the present invention can be similarly applied to an optical pickup actuator of the type provided with.

[0053]

As is apparent from the above description, according to the present invention, a damper base for movably supporting a lens holder for holding an objective lens in a focus direction and a tracking direction via a suspension wire is used as an actuator base. Instead of being fixedly installed, the actuator base is swingably supported around the swing axis, so that when the lens holder is driven in the tilt direction, the suspension wire is not twisted. Can be prevented. This makes it possible to prevent a new resonance of the objective lens due to the twist of the suspension wire. The driven body driven by the tilt drive device according to the present invention is a damper base,
Since the suspension wire and the movable portion are relatively lightweight, the tilt of the optical axis can be corrected at high speed with low power consumption.

[Brief description of drawings]

FIG. 1 is a perspective view of a conventional optical pickup actuator.

FIG. 2 is a perspective view of an optical pickup actuator according to an embodiment of the present invention.

FIG. 3 is an exploded perspective view of the optical pickup actuator shown in FIG.

FIG. 4 is a perspective view showing a state in which the optical pickup actuator shown in FIG. 2 is covered with a cover.

[Explanation of symbols]

10A movable part 11 objective lens 12A lens holder 21A actuator base 22A damper base (suspension wire support part) 341-344 suspension wire 40 tilt drive device 41 tilt coils 46, 47 tilt magnet

Claims (4)

[Claims] 1. A movable part including a lens holder for holding an objective lens, and a damper for supporting the movable part so as to be displaceable in a focus direction and a tracking direction via a plurality of suspension wires extending from both sides thereof. A base, an actuator base that swingably supports the damper base, a main drive device that drives the movable portion in the focus direction and the tracking direction with respect to the actuator base, and the damper with respect to the actuator base. Base
An optical pickup actuator comprising: a tilt driving device that drives in a tilt direction around a swing axis extending in a predetermined direction orthogonal to both the focus direction and the tracking direction. 2. An optical axis that extends in the focus direction and passes through the center of the objective lens when the movable portion is not driven in the focus direction and the tracking direction. 2. The optical pickup actuator according to claim 1, wherein the optical pickup actuator is arranged so as to intersect the axis at right angles to both a tracking axis extending in the tracking direction and passing through the center of the objective lens. . 3. The tilt drive device includes a tilt coil horizontally wound around and held by the damper base,
The optical pickup actuator according to claim 1, comprising a pair of tilt magnets provided on the actuator base so as to face the tilt coil. 4. The optical pickup according to claim 1, wherein the main drive unit includes a tracking coil and a focus coil held by the movable portion, and a yoke and a magnet provided on the actuator base. Actuator.