JPH09320079A - Biaxial actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxial actuator which has sufficiently reduced collision noise generated when an objective lens moves downward in the focusing direction by turning off the focus control. SOLUTION: The biaxial actuator is provided with a lens holder 33 for holding an objective lens, a means for fine adjusting this lend holder 33 in the two directions of the tracking direction and focusing direction and a noise shielding stopper 40 which is provided to an optical base 20b of an optical pickup and formed linger in the focusing direction it restrict movement of the objective lend in the focusing direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact disc (CD), a CD-ROM, a magneto-optical disc, etc.
The present invention relates to an optical disc device for recording and / or reproducing a signal of "optical disc") and a biaxial actuator provided therein.

[0002]

2. Description of the Related Art Conventionally, an optical pickup for an optical disk is constructed as shown in FIGS. 11 and 12, for example. 11 and 12, the optical pickup 1
Is a semiconductor laser element 2 as a light emitting means, an astigmatism correction plate 3a and a grating 3b, a beam splitter 4, a collimator lens 5, a prism mirror 6, an objective lens 7, and a return from the optical disk reflected by the beam splitter 4. It has a Wollaston prism 4a, a multi-lens 4b, and a photodetector which are sequentially arranged in the optical path of light.

In such an optical pickup, the light beam from the semiconductor laser element 2 is transmitted by the astigmatism correction plate 3a,
Pass through the grating 3b and the beam splitter 4 in order,
It is converted into parallel light by the collimator lens 5. Further, the light beam has its optical path bent in the direction of the optical disc D by the prism mirror 6, and reaches the signal recording surface of the optical disc D by the objective lens 7. In the optical pickup, the return light reflected by the signal recording surface is received by the light receiving surface of the photodetector 8, and the recording signal is detected.

[0004] In order to accurately detect a reproduced signal,
The objective lens 7 is finely moved based on a predetermined servo signal so that the light beam from the semiconductor laser element 2 forms a spot at a correct position on the signal recording surface of the optical disc D. The servo of the objective lens includes a tracking servo for finely moving the objective lens along the radial direction of the disc with respect to the recording track of the optical disc, and a direction for approaching and separating from the signal recording surface of the optical disc along the optical axis. Focusing servo for finely moving the objective lens is performed.

[0005]

By the way, in the optical pickup having such a structure, the objective lens 7 is
It is supported by the biaxial actuator 7a of FIG. 13 so as to be movable in the biaxial directions, that is, the focus direction and the tracking direction. In particular, since the objective lens 7 can be moved in the focus direction along the optical axis thereof, the objective lens 7 can be moved to the direction shown in FIG. 13 when the focus servo is turned off.
In some cases, as indicated by an arrow X, the lens holder 9a of the biaxial actuator 7a supporting the objective lens 7 comes into contact with the optical base 9b of the optical pickup 1 by being lowered by gravity.

At this time, when the objective lens 7 and the lens holder 9a hit the optical base 9b, a collision sound is generated. Therefore, in order to reduce the collision sound, the soundproof sheet 9c is provided on the optical base 9b. Is provided. However, since the soundproof sheet 9c is thin in order to make the optical pickup 1 as small as possible, its soundproofing effect is relatively small, and the above-described collision noise cannot be sufficiently reduced. was there.

In view of the above points, the present invention provides a biaxial actuator in which the focus servo is turned off or the collision noise when the objective lens is lowered in the focus direction is sufficiently reduced. It is intended to provide an optical disk device using the optical disk device.

[0008]

According to the present invention, the above object is to provide a lens holder for holding an objective lens, means for finely moving the lens holder in two directions of a tracking direction and a focusing direction, and the objective lens of the objective lens. This is achieved by a biaxial actuator that is provided on the optical base of the optical pickup and that is provided with a soundproof stopper that is long in the focus direction in order to regulate movement in the focus direction.

According to the above construction, the movement of the objective lens in the focus direction is restricted by coming into contact with the soundproof stopper, and the collision sound is reduced by the action of the soundproof stopper. At that time, since the soundproof stopper is formed to be long in the focus direction, the total length of the soundproof stopper that contributes to the soundproofing action becomes long, so that the collision noise is sufficiently reduced.

When the soundproof stopper penetrates the optical base in the focusing direction and the tip of the soundproof stopper projects so as to face the objective lens, the soundproof stopper is housed in the optical base for almost the entire length. Therefore, the presence of the soundproofing stopper does not make the entire optical pickup thick.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS.
The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are added. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

FIG. 1 shows an embodiment of an optical disk device incorporating an optical pickup according to the present invention.
In FIG. 1, an optical disk device 10 includes an optical disk 11
Spindle motor 12 as a driving means for rotationally driving the motor
And an optical pickup 13. Here, the spindle motor 12 is drive-controlled by the optical disk drive controller 14 and rotated at a predetermined rotation speed.

Further, the optical pickup 13 irradiates the signal recording surface of the rotating optical disc 11 with light to record a signal, or detects light returning from the signal recording surface. The reproduction signal based on the returning light is output to the signal demodulator 15.

As a result, the recording signal demodulated by the signal demodulator 15 is error-corrected by the error correction circuit 16 and sent to the external computer or the like via the interface 17. With this, the external computer etc.
The signal recorded on the optical disk 11 can be received as a reproduction signal.

The optical pickup 13 is connected to a head access control unit 18 for moving a predetermined recording track on the optical disk 11 by a track jump or the like. Further, at the moved predetermined position, a servo circuit 19 for moving the objective lens in the focusing direction and the tracking direction is connected to a biaxial actuator (described later) that holds the objective lens of the optical pickup 13. There is.

2 and 3 show the optical disk device 10 described above.
The optical pickup 20 is the same as the optical pickup 13 described above. 2 and 3, the optical pickup 20 includes a semiconductor laser element 21 and an astigmatism correction plate 22a.
And a grating 22b as a light splitting means, a beam splitter 23 as a light splitting means, a collimator lens 24, a prism mirror 25, an objective lens 26, and a Wollaston prism 27 and a multi-lens 28 arranged in a splitting optical path by the beam splitter 23. And photodetector 29
And a biaxial actuator 30 for moving the objective lens 26 in the biaxial directions.

The semiconductor laser device 21 is a light emitting device utilizing recombination light emission of a semiconductor and is used as a light source. The light beam emitted from the semiconductor laser device 21 is
It is guided to the astigmatism correction plate 22a.

The astigmatism correction plate 22a is a parallel flat plate and is arranged so as to be inclined by a predetermined angle with respect to the optical axis.
The astigmatism correction plate 22a corrects the astigmatism of the light beam emitted from the semiconductor laser element 21.

The grating 22b is a diffraction grating that diffracts incident light. The light beam incident from the semiconductor laser element 21 through the astigmatism correction plate 22a is a main beam composed of 0th-order diffracted light and plus / minus first order. It is used to split at least three light beams of a side beam consisting of broken light. Therefore, another splitting element such as a hologram element may be used as long as it can split and generate at least three light beams.

The beam splitter 23 is a polarization beam splitter. This polarization beam splitter is arranged with its polarization separation film 23a inclined by 45 degrees with respect to the optical axis, and separates the light beam from the grating 22b and the return light from the signal recording surface of the optical disc D. That is, a part of the light beam from the semiconductor laser device 21 is transmitted through the polarization separation film 23 a of the beam splitter 23, and a part of the returned light is included in the polarization separation film 23 a of the beam splitter 23.
Is reflected by.

The collimator lens 24 is a convex lens and a concave lens, and converts the light beam from the beam splitter 23 into parallel light.

The prism mirror 25 is an optical path bending means and reflects the parallel light beam from the collimator lens 24 upward by 90 degrees and reflects the return light from the optical disk D in the horizontal direction.

The objective lens 26 is a convex lens, and forms an image of the parallel light from the collimator lens 25 on a desired track on the signal recording surface of the optical disc D which is rotationally driven.

Here, the objective lens 26 is supported by a biaxial actuator 30 described later so as to be movable in the biaxial directions, that is, the focusing direction and the tracking direction.

The Wollaston prism 27 emits a plurality of light beams by performing polarization separation on the basis of the return light beam from the optical disc D. The multi-lens 28, which is a cylindrical lens and a concave lens, imparts astigmatism to the incident light and adjusts the optical path length in order to detect a focus error signal for the return light beam.

The photodetector 29 has a light receiving portion for the return light beam that has passed through the beam splitter 23.

Here, each optical element except the objective lens 26, that is, the semiconductor laser element 21 and the astigmatism correction plate 22.
a, grating 22b, beam splitter 23, collimator lens 24, prism mirror 25, Wollaston prism 27, multi-lens 28 and photodetector 29.
Is an optical pickup 20 configured as shown in FIG.
The optical bases 20b supported so as to be movable in the radial direction of the optical disc D along the guides 20a provided on the optical disc D are fixedly held.

FIG. 7 shows the structure of the biaxial actuator 30. In FIG. 7, the biaxial actuator 3
0 is the optical base 20b of the optical pickup 20 of FIG.
An XY base 31 movably adjustable in the XY directions, and a movable part holder 32 that supports the XY base 31 so as to be movable in the optical axis direction and swingable around the swing axis. And a lens holder 33, an objective lens 26 whose optical axis is held parallel to the swing axis with respect to the lens holder 33, and driving means for the objective lens 26, which will be described later.

The movable part holder 32 is entirely made of a resin such as rubber-like polyester elastomer, and the lens holder 33 is attached to the movable part side 32a, and the fixed part side 32b is attached to the movable part side 32a. XY
It is fixed to the base 31. Further, in the movable part holding body 32, the movable part side 32a has an arrow Fc.
A link having a substantially parallelogram-shaped longitudinal section is configured so that the link can be moved in the vertical direction (focusing direction) indicated by s. Furthermore, in the movable part holder 32, the movable part side 32a is
A pair of vertically extending hinges 32c, 32 so as to be movable in the horizontal direction (tracking direction) indicated by the arrow Trk.
d.

The driving means for the objective lens is composed of a focusing coil 34 and a tracking coil 35 provided on the lens holder 33, a yoke 36 fixedly arranged on the XY base 31 and a magnet 37 attached thereto. Has been done. That is, a pair of driving means for the objective lens is provided on the left and right sides of FIG. The focusing coil 34 is wound on the side surface of the lens holder 33 along the same direction as the paper surface of FIG. 7, and its effective conductor portion is arranged in the parallel magnetic field of the magnet 37 and the yoke 36. The two tracking coils 35 are fixed to the side surface of the focusing coil, and the effective conductor portions are arranged in the parallel magnetic field of the magnet 37 and the yoke 36 so that the tracking coil 35 extends in a direction orthogonal to the winding direction of the focusing coil 35. Is wound on.

By energizing the focusing coil 34 and the tracking coil 35 respectively, the magnetic flux generated in each of the coils 34 and 35 is changed to the above-mentioned yoke 3
The lens holder 33 and the objective lens 26 are driven and controlled in the focus direction and the tracking direction by interacting with the magnetic flux generated by the magnet 6 and the magnet 37.

Further, as shown in FIGS. 8 and 9, the optical disk device 10 incorporating the optical pickup 20 is provided with a soundproof stopper 40 for restricting the movement of the lens holder 33 of the objective lens 26 in the focus direction. .

The soundproof stoppers 40 are arranged on both sides of the prism mirror 25 in the optical base 20b, as shown in FIG.
As shown in FIG. 0, it is composed of a base portion 41 that extends in the lateral direction in a slender shape below the optical base 20b, and a pair of stopper portions 42 and 43 that extend upward from the vicinity of both ends of the base portion 41. The stopper portions 42 and 43 have the same shape and are described for a long time.
When 0 is mounted from the bottom of the optical base 20b, the lengths of the stoppers 42 and 43 are selected so that the tips of the stoppers 42 and 43 extend beyond the upper end of the optical base 20b. Then, in the middle of the stopper portions 42, 43, the hook portion 42a,
43a is formed.

The soundproof stopper 40 is formed of, for example, an elastic material such as synthetic resin, so that when the lens holder 33 of the objective lens 26 abuts on the tips of the stopper portions 42 and 43, the stopper portions 42 are formed. ，
By absorbing this impact over the entire length of 43, the collision noise can be sufficiently reduced.

Further, as shown in FIG. 4, the soundproof stopper 40 has a prism mirror mounting portion 20 of the optical base 20b.
Through holes 20 provided on both sides of c and penetrating vertically
The stoppers 42 and 43 are inserted into d and 20e. Hook portions 42a and 43a of the stopper portions 42 and 43
Is an upward step in the through holes 20d and 20e (see FIG. 9).
By engaging with the optical base 20b, the optical base 20b is fixedly held.

The soundproof stopper 40 attached to the optical base 20b in this manner has the stopper portions 42, 4
As shown in FIG. 8 and FIG.
In a region of the upper surface of 0b, which faces the lens holder 33 of the objective lens 26, it slightly projects upward from the upper surface of the optical base 20b.

The optical disk device 10 incorporating the optical pickup according to the present embodiment is configured as described above and operates as follows. First, the optical disk device 10
The optical disk D is rotationally driven by rotating the spindle motor 12 of. And the optical pickup 2
When 0 is moved in the radial direction of the optical disc D along the guide 20a, the optical axis of the objective lens 26 is moved to a desired track position of the optical disc D, so that access is performed.

In this state, in the optical pickup 20, the light beam from the semiconductor laser element 21 is split into three light beams by the grating 22b, then transmitted through the beam splitter 23, and collimated by the collimator lens 24. After being converted into light, it is reflected toward the optical disc D by the prism mirror 25. In addition, the light beam
An image is formed on the signal recording surface of the optical disc D via the objective lens 26. The return light from the optical disk D is again the objective lens 26, the prism mirror 25, and the collimator lens 2
4, enters the beam splitter 23, is reflected by the polarization separation film 23a of the beam splitter 23, and forms an image on the photodetector 29 via the Wollaston prism 27 and the multi-lens 28. As a result, the recording signal of the optical disc D is reproduced based on the detection signal of the photodetector 29.

At this time, the tracking error signal is detected by the signal demodulator 15 from the detection signal from the photodetector 29, and the focusing error signal is detected by the astigmatism method. Then, via the optical disk drive controller 14, the servo circuit 19 servo-controls a drive current to the focusing coil 34 and the tracking coil 35. As a result, the magnetic field generated in the focusing coil 35 is controlled by controlling the drive current of the focusing coil 35, and the magnet 37 and the coil 36 are controlled.
By acting with the magnetic field by the lens holder 33
However, the movement is adjusted in the focusing direction to perform focusing. Further, the magnetic field generated in the tracking coil 35 acts on the magnetic field generated by the magnet 37 and the yoke 36, whereby the lens holder 33 is moved and adjusted in the tracking direction, and tracking servo is performed.

Here, by turning off the focus servo of the biaxial actuator 30, the lens holder 3
When 3 becomes free in the focus direction, the lens holder 33 and the objective lens 26 will descend due to gravity. As a result, the lens holder 33 comes into contact with the tips of the stopper portions 42 and 43 of the soundproof stopper 40 protruding from the upper surface of the optical base 20b. At that time, the impact of the contact of the lens holder 33 with the stopper portions 42, 43 is absorbed over the entire length of the stopper portions 42, 43. That is, the conventional soundproof tape 9c (see FIG. 13)
The impact sound is absorbed by a stroke that is sufficiently longer than that of the above. Therefore, the lens holder 33 and the objective lens 26
The collision sound of the above-mentioned on the upper surface of the optical base 20b is sufficiently reduced.

In the optical disk device 10 and the optical pickup 20 according to the above-mentioned embodiment, the biaxial actuator 30 is shown to have the movable part holder 32, but the present invention is not limited to this, and the suspension spring type. Obviously, it may be a biaxial actuator or the like.

In the optical disk device 10 and the optical pickup 20 according to the above-described embodiment, the configuration of the polarization optical pickup for reproducing the magneto-optical disk is shown, but the present invention is not limited to this, and the compact disk (CD) or C is used.
It is obvious that the present invention can be applied to a non-polarization optical pickup for D-ROM and an optical disc device.

[0043]

As described above, according to the present invention, the focus control is turned off, and the collision noise when the objective lens is lowered in the focus direction is sufficiently reduced. An actuator can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of an optical disk device incorporating an optical pickup according to the present invention.

FIG. 2 is a plan view showing a configuration of an optical pickup in the optical disc device of FIG.

3 is a bottom view showing a configuration of an optical pickup in the optical disc device of FIG.

FIG. 4 is a perspective view of an optical base in the optical pickup of FIG.

5 is a side view showing an optical system in the optical pickup of FIG.

FIG. 6 is a plan view showing an optical system in the optical pickup of FIG.

7 is a plan view of a biaxial actuator in the optical pickup of FIG.

8 is a side view of the vicinity of a soundproof stopper in the optical pickup of FIG.

9 is a cross-sectional view near the soundproof stopper of FIG.

FIG. 10 is an enlarged plan view and enlarged front view showing the soundproof stopper of FIG.

FIG. 11 is a side view showing an optical system in an example of a conventional optical pickup.

12 is a plan view showing an optical system in the optical pickup of FIG.

13 is an enlarged sectional view showing a soundproof structure of an objective lens in the optical pickup of FIG.

[Brief description of reference numerals]

10 ... Optical disk device, 11 ... Optical disk, 1
2 spindle motor 13 optical pickup 14 optical disk drive controller 15
... Signal demodulator, 16 ... Error correction circuit, 17 ...
Interface 18: head access control unit 20, optical pickup, 20a guide, 20b optical base, 20c prism mirror mounting unit, 20d, 20e through hole, 21 ...
Semiconductor laser device, 22a ... Astigmatism correction plate, 22
b ... Grating, 23 ... Beam splitter, 24 ... Collimator lens, 25 ... Prism mirror, 26 ... Objective lens, 27 ... Wollaston prism, 28 ... Multilens, 29 ... Photodetector, 30 ... Biaxial actuator, 31 ... XY
Base, 32 ... Movable part holder, 33 ... Lens holder, 34 ... Focus coil, 35 ... Tracking coil, 36 ... Yoke, 37 ... Magnet, 40 ... Soundproof stopper, 41 ... Base portion, 42, 43 ... Stopper portion.

Claims (5)

[Claims] 1. A lens holder for holding an objective lens, means for finely moving the lens holder in two directions of a tracking direction and a focus direction, and an optical pickup optical device for restricting movement of the objective lens in the focus direction. A biaxial actuator, comprising: a soundproof stopper provided on a base and elongated in the focus direction. 2. The biaxial actuator according to claim 1, wherein the soundproof stopper is made of an elastic material. 3. The biaxial actuator according to claim 1, wherein the soundproof stopper is attached to the optical base. 4. The soundproof stopper penetrates the optical base in the focusing direction, and a tip of the soundproof stopper protrudes so as to face the objective lens.
The biaxial actuator according to 1. 5. A means for irradiating a signal recording surface of an optical disk with a light beam emitted from a light source through an objective lens, and a light detecting means having a light receiving portion for receiving a returning light beam from the signal recording surface of the optical disk. A biaxial actuator for finely moving the objective lens, the biaxial actuator comprising a lens holder for holding the objective lens, and means for finely moving the lens holder in two directions of a tracking direction and a focus direction, An optical disc device, comprising: a soundproof stopper, which is provided on an optical base of an optical pickup and is elongated in the focus direction, for restricting movement of the objective lens in the focus direction.