KR100444563B1 - 2-axis actuator and optical disk device - Google Patents

Abstract

Biaxial actuators for use in a plurality of types of signal recording / reproducing apparatuses for optical recording media are designed to be suitable for recording media of different formats in signal recording and / or reproduction. The biaxial actuator includes a support shaft disposed on the base plate and a lens holder rotatably supported around the support shaft. The lens holder is equipped with a plurality of objective lenses having different numerical apertures NA and coils for focusing and tracking. Depending on the type of optical recording medium, the objective lens is switched and used.

Description

2-axis actuator and optical disk device

The present invention relates to a biaxial actuator and an optical disc apparatus in optical pickup for recording and / or reproducing information on an optical recording medium (hereinafter referred to as an "optical disc") such as a compact disc (CD), a CDROM or a magneto-optical disc. In particular, the present invention relates to a biaxial actuator and an optical disc apparatus capable of reproducing a plurality of types of optical discs having different disc formats.

Background Art [0002] Conventionally, optical pickup for optical disc reproduction includes, for example, a semiconductor laser element as a light emitting means, an objective lens for irradiating light from the semiconductor laser element onto the optical disc, and the objective lens to be moved in the biaxial direction. It consists of a two-axis actuator which can be supported, a photodetector for detecting the return light from the optical disk, and a servo circuit for driving control of the two-axis actuator in the focusing direction and the tracking direction in accordance with the detection signal of the photodetector.

Here, the two-axis actuator is movable in the axial direction with respect to the support shaft extending perpendicular to the signal recording surface of the optical disc, as disclosed, for example, in US Pat. Nos. 4,473,274 and 4,571,026. A lens holder rotatably supported around the shaft, an objective lens in which the optical axis is supported parallel to the support shaft at a position eccentric from the support shaft of the lens holder, and a two-axis base on which the support shaft is mounted.

In addition, the biaxial actuator has a focusing coil wound on a cylindrical outer circumferential surface of the lens holder, and a pair of tracking coils are mounted on opposite sides of the outer surface of the focusing coil. On the other hand, on the biaxial base, a magnet is disposed so as to face the focusing coil and the tracking coil.

According to the optical pickup having such a configuration, the magnetic flux generated in each coil is supplied from the outside to each coil by driving the drive voltage controlled by the tracking servo and the focusing servo from the servo circuit. In interaction with the magnetic flux, the lens holder rotates around the support shaft and slides along the support shaft.

As a result, the objective lens eccentrically supported from the rotation center of the lens holder is moved in the tangential direction of the optical disc by the rotation of the lens holder, thereby substantially moving properly with respect to the tracking direction, and at the same time, the axial direction by the slide of the lens holder. By moving to, it moves appropriately with respect to the focusing direction.

As a result, the light irradiated on the optical disc forms a spot accurately on the signal recording surface of the optical disc, and the returned light from the optical disc is incident on the optical detector so that the reproduction signal of the optical disc is detected in accordance with the detection signal from the optical detector. do.

By the way, the optical disc is an auxiliary storage device of a computer and a package medium for audio and image information, and the density of signal recording discs is increasing. In order to realize this density, the numerical aperture NA of the objective lens is increased so that the optical disc is formed on the optical disc. Record to or play back from an optical disc.

However, when the numerical aperture NA of the objective lens is increased, there is a problem that the allowable range for the tilt of the optical disk during signal reading is reduced.

In the optical disc, the signal recording surface is generally formed through a transparent substrate having a predetermined disc substrate thickness (generally, 1.2 mm in the case of a compact disc, etc.), so that the optical disc is formed with respect to the optical axis of the objective lens of the optical pickup. When inclined, wavefront aberration occurs, which adversely affects the reproduction signal (RF signal). At this time, in relation to the wave front aberration, the third order comma of the numerical aperture NA, about one power of the skew angle θ , and the third coma aberration which occurs in proportion to the disk substrate thickness are dominant. .

Therefore, an optical disc having a 1.2 mm thick transparent substrate made of polycarbonate produced at low cost has a skew angle θ of, for example, plus or minus 0.5 to plus or minus 1 degree. The image forming spot on the signal recording surface of the optical disk in accordance with the light beam irradiated from the image becomes asymmetrical.

Since the intersymbol interference in the recording signal increases significantly, accurate RF signal reproduction cannot be performed.

Therefore, paying attention to the fact that the third coma aberration is proportional to the disk substrate thickness of the optical disk, the signal recording surface is disposed on a transparent substrate having a thickness of 0.6 mm, and reducing the substrate thickness of the optical disk can halve the third coma aberration. Wavefront aberration is reduced.

In order to realize the high density of the optical disc as described above, it is effective to use the optical disc whose substrate thickness has been reduced as described above. In this case, as the optical disk, two standards having different characteristics, that is, a relatively thick disk substrate thickness (for example, 1.2 mm) and a relatively thin disk substrate thickness (for example, 0.6 mm) are mixed.

In the optical disc apparatus for recording / reproducing an optical disc, there is a need for such an apparatus having compatibility with a disc having different characteristics described above.

If a parallel plate of thickness t is inserted into the optical path from the objective lens to the signal recording surface of the optical disc, spherical aberration proportional to t x (NA) 4 occurs with respect to the thickness t and the numerical aperture NA, and therefore, the objective lens Is designed to cancel this spherical aberration.

However, if the thickness of the disc substrate is different, the spherical aberration is also different. Therefore, using an objective lens having a numerical aperture NA corresponding to one standard, for example, 0.6 mm, the thickness of the other substrate, for example, When attempting to play an optical disc such as a compact disc, a recordable optical disc or a magneto-optical disc of 1.2 mm, the above-described fourth spherical aberration T × (NA) 4 occurs due to the difference T of the thickness of the optical disc substrate. Therefore, the tolerance of the error of the thickness of the disk substrate to which the optical pickup can cope is greatly exceeded. Therefore, there is a problem that a signal cannot be detected accurately from the feedback light from the optical disc.

Thus, there has been a problem that conventional biaxial actuators cannot reproduce a plurality of different types of optical discs.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a biaxial actuator and an optical disc apparatus in which any type of optical disc is switched to a corresponding objective lens so that the optical disc can be reproduced accurately.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the overall configuration of an embodiment of an optical disk apparatus incorporating a biaxial actuator according to the present invention.

FIG. 2 is a plan view showing the configuration of an optical pickup in the optical disk apparatus of FIG.

FIG. 3 is a longitudinal sectional view of the optical laser of FIG. 2 along an optical path from a semiconductor laser element to a granular mirror, a collimator lens, and an objective lens; FIG.

4 is a cross-sectional view of the biaxial actuator in the optical pickup of FIG.

FIG. 5 is a plan view of a biaxial actuator in the optical pickup of FIG. 2; FIG.

6 is a side view of the biaxial actuator in the optical pickup of FIG. 2; FIG.

FIG. 7 is a perspective view of a biaxial actuator in the optical pickup of FIG. 2; FIG.

8 is an exploded perspective view of the two-axis actuator of FIG. 7;

FIG. 9 is a schematic plan view showing a magnetic circuit at a first midpoint position of a lens holder in the biaxial actuator of FIG. 7; FIG.

Fig. 10 is a schematic plan view showing a magnetic circuit when the lens holder moves from a first midpoint position to a second midpoint position in a two-axis actuator.

Fig. 11 is a side view showing the lens holder at the first mid-point position in the two-axis actuator.

Fig. 12 is a side view showing the lens holder at the second midpoint position in the two-axis actuator.

Fig. 13 is a block diagram showing an electrical configuration for switching the mid-point position of the lens holder in the two-axis actuator of Fig. 7.

<Description of the code | symbol about the principal part of drawing>

DESCRIPTION OF SYMBOLS 10 Optical disc device, 11 Optical disc, 12 Spindle motor, 13 Optical pickup, 14 Optical disc drive controller, 15 Signal demodulator, 16 Error correction circuit, 17 Interface, 18 Head access control part, 20 Optical Pickup, 21: semiconductor laser element, 22: grating, 23: beam splitter, 24: granular mirror, 25: collimator lens, 26, 26a, 26b: objective lens, 27: photodetector, 28: guide, 29: optical base, 30: 2-axis actuator, 31: 2-axis base, 32: support shaft, 33: lens holder, 34: focusing coil, 35a, 35b: tracking coil, 36: focusing yoke, 37: focusing magnet, 38: Tracking yoke, 39: tracking magnet, 39a, 39b: magnetic pole, 40, 41: iron piece.

In one aspect, the present invention provides a support shaft disposed on a base plate perpendicular to a signal recording surface of a recording medium, a lens holder slidable along the support shaft and rotatably supported around the support shaft; A plurality of objective lenses disposed in the lens holder, a focusing coil mounted on the lens holder to drive the lens holder in a focusing direction, a tracking coil mounted on the lens holder to drive the lens holder in a tracking direction, and As a magnetic generating means disposed on the base plate, there is provided a two-axis actuator comprising magnetic generating means fixedly disposed so as to face the focusing coil and the tracking coil, respectively.

In another aspect, the present invention provides a driving means for rotating an optical disk, a light source for irradiating laser light, an objective lens for irradiating a laser light irradiated by the light source, an objective lens for focusing and Detecting from the photodetector means a biaxial actuator movably supporting the tracking direction, a photodetector means for detecting a return laser light irradiated on and reflected from the optical disc, and an objective lens supported by the biaxial actuator An optical disk apparatus for recording and / or reproducing an optical disk comprising a servo means for moving in a focusing direction and a tracking direction in accordance with a signal, and moving means for moving the two-axis actuator in the radial direction of the optical disk. The two-axis actuator includes a support shaft disposed on the base plate perpendicular to the signal recording surface of the optical disk, a lens holder slidable along the support shaft and rotatably supported around the support shaft, and disposed on the lens holder. A plurality of objective lenses, a focusing coil mounted on the lens holder and driving the lens holder in a focusing direction, a tracking coil mounted on the lens holder and driving a lens holder in a tracking direction, the focusing coil and And magnetic generating means fixedly disposed on the base plate so as to face the tracking coils, respectively, wherein the objective lens is selectively moved in the optical path of the laser beam.

According to the present invention, any type of optical disc can be accurately reproduced by appropriately switching to the corresponding objective lens.

Next, a preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 10.

In addition, although embodiment described next shows the suitable specific example of this invention and the various technically preferable limitation was added, the scope of the present invention has the meaning of limiting this invention especially in the following description. Unless otherwise described, it is not limited to these aspects.

Fig. 1 shows an embodiment of an optical disk apparatus incorporating a biaxial actuator according to the present invention.

In FIG. 1, the optical disc apparatus 10 includes a spindle motor 12 as a drive means for rotating and driving the optical disc 11, and an optical pickup 13. As shown in FIG.

Here, the spindle motor 12 is drive-controlled by the optical disk drive controller 14 and rotates at a predetermined rotational speed.

In addition, the optical pickup 13 irradiates light onto the signal recording surface of the rotating optical disk 11 to record the signal or to detect a feedback light from the signal recording surface. Outputs a reproduction signal according to the feedback light.

As a result, the recording signal demodulated by the signal demodulator 15 is error-corrected through the error correction circuit (ECC) 16 and sent out to the external computer or the like through the interface 17. Thus, the external computer or the like can receive a signal recorded on the optical disc 11 as a reproduction signal.

The optical pickup 13 is connected with a head access control unit 18 for moving the optical pickup 13 by track jump or the like, for example, to a predetermined recording track on the optical disc 11. In addition, the optical pickup 13 includes a servo for moving the objective lens in the focusing direction and the tracking direction with respect to the biaxial actuator (to be described later) that supports the objective lens of the optical pickup 13 at the moved predetermined position. The circuit 19 is connected.

2 and 3 show an optical pickup built into the optical disk apparatus 10. As shown in FIG. 2 and 3, the optical pickup 20 includes a semiconductor laser element 21 as a light source, a grating 22 as light splitting means, a beam splitter 23 as light separating means, and a granular mirror as optical path bending means ( 24), the collimator lens 25, the objective lens 26 and the photodetector 27, and the biaxial actuator 30 for moving the objective lens 26 in the biaxial direction are comprised.

The semiconductor laser element 21 is a light emitting element using recombination light emission of a semiconductor and is used as a light source. The light beam emitted from the semiconductor laser element 21 is guided to the grating 22.

The grating 22 as the light dividing means is a diffraction grating for diffracting incident light, and the main beam and the positive minus first diffracted light made of the light beam emitted from the semiconductor laser element 21 are composed of zero-order diffracted light. It is used to separate into at least three light beams of the side beam consisting of.

The beam splitter 23 is provided with its reflection surface 23a inclined at 45 degrees with respect to the optical axis, and separates the light beam from the grating 22 and the return light from the signal recording surface of the optical disc 11. That is, the light beam from the semiconductor laser element 21 is reflected by the reflecting surface 23a of the beam splitter 23, and the returned light passes through the beam splitter 23.

3 and 4, the granular mirror 24 is an optical path bending mirror and reflects the light beam reflected by the beam splitter 23 in the vertical direction indicated by arrow A in FIG. The returned light from the light is reflected in the horizontal direction indicated by arrow B in FIG.

In this case, the granular mirror 24 is selected and arranged so that its inclination direction forms an angle of 45 degrees with respect to the track direction of the optical disc 11 (tangential direction of the disc 11).

The collimator lens 25 is a convex lens, as shown in FIG. 3 and FIG. 4, and converts the light beam reflected by the granular mirror 24 into parallel light.

In this case, the collimator lens 25 is disposed in the optical path bent by the granular mirror 24, that is, in the optical path perpendicular to the signal recording surface of the optical disc.

As a result, the distance between the beam splitter 23 and the granular mirror 24 is relatively short, and the biaxial actuator 30 and the optical pickup 20 also have a compact optical disk device 10. Moreover, since the collimator lens 25 is arrange | positioned between the objective lens 26 and the granular mirror 24, the support shaft 32 will be formed comparatively long, and the lens holder 33 will be stabilized and supported.

In the collimator lens 25, as shown in Fig. 5, the side edge on the support shaft 32 side is cut as indicated by the broken line 25a, and the collimator lens 25 is disposed around the support shaft 32 and its surroundings. It does not interfere with the focusing coil 34, the focusing yoke 36, or the focusing magnet 37. For example, since the length of the track direction of the optical disc 11 of the collimator lens 25 is sufficiently taken, such cut 25a has little influence on tracking servo or the like.

3 and 4, the objective lens 26 is a convex lens, and parallel light from the collimator lens 25 is imaged on a desired track of the signal recording surface of the optical disk 11 to be rotated.

Here, the objective legs 26 are supported by the two-axis actuator 30 of the axial slide rotation type so as to be movable in two axes, i.e., the focusing direction and the tracking direction, and correspond to two different types of optical discs. It consists of two objective lenses 26a and 26b designed, and is supported to be inserted into the optical path alternatively by a lens holder which is a movable part of the biaxial actuator 30, as will be described later.

The photodetector 27 is configured to have a light receiving portion with respect to the feedback light beam that has passed through the beam splitter 23.

The semiconductor laser element 21, the grating 22, the beam splitter 23, the granular mirror 24, the collimator lens 25, and the photodetector 27 are two axes which are fixed parts of the biaxial actuator 30. It is fixedly arranged on the base 31.

7 and 8 show the configuration of the biaxial actuator 30.

In Figs. 7 and 8, the biaxial actuator 30 is an optical base 20 which is movably supported in the radial direction of the optical disc 11 along the guide 28 with the optical pickup 20 in the C direction of Fig. 29, the support shaft 32 extending perpendicularly to the signal recording surface of the optical disc 11 on the 2-axis base 31, skew-adjusted and mounted, and the support shaft 32 A substantially rectangular or rectangular lens holder 33 which is axially movable and rotatably supported around the axis, and the optical axis is supported parallel to the support axis at a predetermined distance from the rotation axis of the lens holder and at different angular positions. Two objective lenses 26a and 26b.

Here, of the two objective lenses, the objective lens 26a is, for example, a lens having a relatively large numerical aperture NA (for example, NA = 0.6) for a high density optical disk (optical disk of the second type), and is a conventional optical disk. The numerical aperture NA for the optical disc of the first kind (for example, CD) is formed to be larger in diameter than the objective lens 26b having a relatively small value (for example, NA〓0.45).

In addition, the lens holder 33 is formed below the support shaft 32 and the concentric cylindrical portion 101, the lens holder 33, the signal of the optical disk 11, respectively The flange 102 of the flat form which has the upper surface 102c parallel to the surface, and the side surfaces 102a and 102b perpendicular to it is formed.

A pair of objective lenses 26a, 26b are disposed on the upper surface 102c of the flange 102 of the lens holder 33, and a relatively small objective lens 26b is disposed on the rotation center side of the optical disk 11. It is.

In addition, the lens holder 33 has concentric cylindrical focusing coils 34 mounted on the cylindrical portion 101 below and side surfaces 102a and 102b opposite to each other with respect to the support shaft 32. And a pair of tracking coils 35a and 35b mounted on the head).

On the other hand, on the biaxial base 31 of the biaxial actuator 30, a pair of focusing coils 36 and 36 and a pair of tracking yokes 38 and 38 are used for the semiconductor laser element 21. It is disposed at a position not to block the optical path of the emitted light from. Focusing coils 36 and 36 are disposed with respect to the focusing coil 34 so as to face each other from the outside of the cylindrical portion 101 on the opposite side with respect to the support shaft 32, and the tracking yokes 38 and 38 are provided. Are disposed so as to face the tracking coils 35a and 35b from the outside, respectively.

A pair of focusing magnets 37, 37 are mounted inside the focusing coils 36, 36, and a pair of tracking magnets 39, 39 are located inside the tracking yokes 38, 38. Is mounted.

In this way, the flanges of the lens holder 33 are formed in a relatively long shape in which the tracking coils 35a and 35b are disposed at both ends of the flange 102 of the lens holder 33 and rotated about the support shaft 32. Equal driving force is applied at both ends of the 102. As a result, the lens holder 33 can smoothly rotate.

The lens holder 33 of the present embodiment is configured such that the granular mirror 24 is close to the focusing coil and disposed below the flange 102.

The focusing coil 34 is wound around the outer circumferential portion of the cylindrical portion 101 separately from the tracking coils 35a and 35b and is disposed relatively close to the peripheral surface of the support shaft 32. As a result, the focusing coil 34 is wound around the wire rod made of a conductor with a small diameter in the horizontal direction, and is formed as a small diameter as a whole. In response to this, the focusing yoke 36 and the magnet 37 are also close to the support shaft 32. As a result, the focusing coil 34 can be made small in size as a whole and the effective conductor length can be increased.

Moreover, the said tracking magnet 39 is comprised so that it may become reverse polarity with respect to right and left from the center of the axial direction of the support shaft 32. As shown in FIG. For example, the tracking magnet 39 is disposed so as to be the S pole 39a and the N pole 39b in the clockwise direction with respect to the support shaft 32 as shown in FIG. 9.

In addition, the tracking coils 35a and 35b have a winding portion disposed parallel to the axis of the support shaft 32, and the lateral directions (tracking) of the support shaft 32 are provided on both side surfaces 102a and 102b of the winding portion, respectively. A magnetic body, for example, iron pieces 40 and 41, which are disposed in a direction along the magnetization boundary of the dragon magnet 39, is attached. Thereby, either of the iron pieces 40 or 41 is adsorbed so as to oppose the boundary 39c of the two poles 39a and 39b of the tracking magnet 39 so that the lens holder 33 can A first midpoint position into which the objective lens 26a of the first is inserted in the optical path between the collimator lens 25 and the signal recording surface of the optical disk 11, or a second in which the second objective lens 26b is inserted into the optical path. It is moved to the midpoint position.

Side surfaces 102a and 102b of the lens holder 33 are disposed to be symmetrical with respect to the support shaft 32, and the tracking coils 35a and 35b and the iron pieces 40 and 41 are centered around the support shaft 32. Exposed on sides 102a and 102b to be symmetrical.

By the above arrangement, the objective lenses 26a and 26b are selectively inserted in the optical path between the semiconductor laser element 21 and the signal recording surface of the optical disc 11.

The size and / or shape of the iron pieces 40 and 41 are arbitrarily changed so that the adsorption force by the tracking magnet 39 changes, so as to appropriately set the primary resonance frequency f ₀ of the biaxial actuator 30.

The lens holder 33 is pushed to the side of the support shaft 32 by the iron pieces 40 and 41 adsorbed to the tracking magnets 39 and 39, so that the lens holder 33 and the support shaft 32 This reduces the fluctuations caused by space.

In FIG. 7, the lens holder 33 is shown to be located in the middle of the first midpoint position and the second midpoint position.

Thus, for example, when the objective lens 26a is inserted in the optical path, as shown in FIG. 9, the iron piece 41 is bounded by two magnetic poles 39a and 39b of the opposing tracking magnet 39. By facing 39c, the lens holder 33 is at the first midpoint position, and magnetic flux flows as indicated by the arrow so that the lens holder 33 is held at the first midpoint position. Here, with respect to the tracking coils 35a and 35b, the driving current flows in the direction indicated by the arrow K or the arrow L in FIG. 11, and is represented by arrows p and q in FIG. 11 on the basis of the first midpoint position. As described above, the lens holder 33 is rotated around the support shaft 32 so that the objective lens 26a is moved in the tracking direction substantially tangential to the rotation of the lens holder 33, so that tracking is performed. .

Here, when a current larger than the normal tracking servo current flows to the tracking coils 35a and 35b in the direction indicated by the arrow L in FIG. 11, the tracking magnet in the arrow p direction of FIG. 11 as shown in FIG. 10. In response to the magnetic field of 39, the tracking coils 35a and 35b move to face the magnetic pole 39b. As a result, the iron piece 40 on the opposite side is opposed to the boundary 39c of the magnetic poles 39a and 39b of the tracking magnet 39, as shown in FIG. 12, and the lens holder 33 is at the second midpoint position. The objective lens 26b is inserted into the optical path.

Fig. 13 is a block diagram showing a configuration for such a midpoint position change. In the figure, the disc discrimination unit 63 determines whether the set optical disc is the above-described first type of optical disc or the second type of optical disc. The photodetector 27 is connected to the disc discrimination unit 63. The disc discrimination unit 63 is connected to the midpoint switching signal output unit 65 and the tracking error signal operation circuit 62. The midpoint switching signal output section 65 and the tracking error signal calculation circuit 62 are connected to the drive section 61 of the objective lens. The objective lens driver 61 is a driver for driving the tracking coil, and is connected to the tracking coils 35a and 35b.

The computing circuit 62 and the objective lens driver 61 of the tracking error signal are a tracking servo circuit and are part of the servo circuit 19 of FIG.

The disc discrimination unit 63 obtains, from the photodetector 27, the ID read result of the optical disc set at that time, and determines whether the optical disc of the first type or the optical disc of the second type is made. Alternatively, the disc discrimination unit 63 obtains a detection result in accordance with the difference in the reflection amount of the light due to the difference in the substrate thickness of the set optical disc by the photodetector 27 or another photodetector, and determines the type of the optical disc. . The photodetector 27 measures the number of tracks with respect to a predetermined distance in the radial direction with respect to the optical disc set at that time, and outputs the measurement result to the disc discrimination unit 63. As a result, the disc discrimination unit 63 discriminates the disc. The disc discrimination unit 63 outputs the determination result to the midpoint switching signal output unit 65.

In addition, instead of automatically determining the type of the optical disc set at this time, the user selects an operator as the selection unit 63, and the user switches the information on the type of the optical disc set at the time. Output to the signal output section 65.

The midpoint switching signal output section 65 outputs a signal to the objective lens driver 61 in order to switch the objective lenses 26a and 26b according to the type of the optical disc. The objective lens driver 61 applies a predetermined current or voltage to each tracking coil 35a, 35b to switch the objective lens described above.

In this case, corresponding to the switching operation between the midpoint position in which one of the objective lenses 26a and 26b is in the first state and the midpoint position in which the other is in the second state, each of the tracking coils 35a and 35b is provided. The current or voltage value to be supplied is determined. This current and voltage value are higher than the current or voltage value applied to the tracking coils 35a and 35b by the objective lens driver 61 in accordance with the output from the tracking error signal calculation circuit 62 when the tracking servo is performed. Big. As a result, a large current or voltage is applied to each of the tracking coils 35a and 35b so that the objective lens moves larger than the tracking servo tracking stroke, so that the respective midpoint positions are switched.

The disc discrimination unit 63 then sends the determination result to the tracking error signal calculation circuit 62. As a result, the tracking error signal calculation circuit 62 calculates any one of the tracking error signal according to the type of the optical disc, that is, the tracking error signal by the three-strip method and the tracking error signal by the phase comparison method, to obtain an objective lens. It is sent to the drive part 61.

The optical disk device 10 incorporating the two-axis actuator according to the present embodiment operates as follows.

First, in the case of reproducing a high density optical disk (second type optical disk) having a thickness of 0.6 mm of the transparent substrate, the lens holder 33 is in the first midpoint position as shown in FIG. While 26a is inserted in the optical path, one iron piece 41 attached to the lens holder 33 faces the boundary 39c of the tracking magnet 39.

Here, by rotating the spindle motor 12 of the optical disc apparatus 10, the optical disc 11 is driven to rotate. Then, the optical pickup 20 is moved along the guide 28 in the radial direction of the optical disc 11 indicated by the arrow C in FIG. 2, whereby the optical axis of the objective lens 26a is moved to the desired track of the optical disc 11. Access is performed by moving to a position.

In this embodiment, the relatively small objective lens 26b of the objective lenses 26a and 26b is disposed on the rotation center side of the optical disk, so that the disk does not interfere with the spindle motor 12, and the objective lens 26a ) Moves to a position near the center of the optical disc 11.

In this state, in the optical pickup 20, the light beam from the semiconductor laser element 21 is divided into three light beams by the grating 22 and then reflected on the reflecting surface 23a of the beam splitter 23 The reflection is reflected from the granular mirror 24 toward the optical disk 11. In addition, the light beam is converted into parallel light by the collimator lens 25, and is imaged on the signal recording surface of the optical disc 11 through the objective lens 26a.

At this time, by the objective lens 26a, the numerical aperture NA is appropriately set to, for example, NA # 0.6 corresponding to the high density optical disk, and the light beam is accurately formed on the signal recording surface of the optical disk 11.

The returned light from the optical disc 11 passes through the beam splitter 23 through the objective lens 26a, the collimator lens 25, and the granular mirror 24, and forms an image in the photodetector 27. Thus, the recording signal of the optical disc 11 is reproduced in accordance with the detection signal of the photodetector 27.

At this time, the tracking error signal and the focusing error signal are detected by the signal demodulator 15 from the detection signal from the photodetector 27, and the servo circuit 19 focuses through the optical disk drive controller 14. The drive current to the coil 34 and tracking coils 35a and 35b is servo controlled. Thereby, the current flowing through the focusing coil 34 acts on the magnetic field by the focusing magnet 37 and the focusing yoke 36 by controlling the drive current of the focusing coil 34, thereby providing a lens holder ( 33 is moved and adjusted in the focusing direction in accordance with the support shaft 32, and focusing is performed.

In addition, the drive current flowing in the tracking coils 35a and 35b in the directions of arrows K and L in FIG. 11 acts on the magnetic field by the tracking magnet 39 and the tracking yoke 38, thereby providing a lens holder 33. ) Is rotated around the support shaft 32 on the basis of the first midpoint position, and the objective lens 26a is moved and adjusted in a substantially tangential tracking direction, so that tracking is performed.

Next, for example, when reproducing a normal optical disc (first type optical disc, for example, CD) having a thickness of 1.2 mm, a large current or voltage is applied to the tracking coils 35a and 35b. By flowing, the objective lens is moved at a distance greater than the tracking servo tracking stroke in the direction indicated by the arrow L in FIG. 11, so that the other iron piece 40 attached to the lens holder 33 is tracked as described above. The lens holder 33 is rotated around the support shaft 32 so as to face the boundary 39c of the dragon coil 39 and is moved to the second midpoint position. As a result, the objective lens 26b is inserted into the optical path.

The determination of the optical disc to be reproduced is performed by reading the ID of the optical disc, detecting the amount of reflected light due to the difference in the substrate thickness, and the like. It is clear that the lens may be switched.

Here, in the same manner, the spindle motor 12 of the optical disc apparatus 10 is rotated, and the optical disc 11 is driven to rotate. The optical pickup 20 is moved along the guide 28 in the radial direction of the optical disc 11 so that the optical axis of the objective lens 26b is moved to the desired track position of the optical disc 11 so that access can be made. Is done.

In this state, in the optical pickup 20, the light beam from the semiconductor laser element 21 is divided into three light beams by the grating 22, and then reflected on the reflecting surface 23a of the beam splitter 23 The reflection is reflected from the granular mirror 24 toward the optical disk 11. Further, the light beam is converted into parallel light by the collimator lens 25, and is imaged on the signal recording surface of the optical disc 11 via the objective lens 26b.

At this time, by the objective lens 26b, the numerical aperture NA is appropriately set to, for example, NA〓0.45 in correspondence with a normal optical disk, and the optical beam is accurately imaged on the signal recording surface of the optical disk 11. .

The feedback light from the optical disc 11 passes through the beam splitter 23 through the objective lens 26b, the collimator lens 25, and the granular mirror 24, and forms an image in the photodetector 27. Thus, the recording signal of the optical disc 11 is reproduced in accordance with the detection signal of the photodetector 27.

At this time, the tracking error signal and the focusing error signal are detected by the signal demodulator 15 from the detection signal from the photodetector 27, and the servo circuit 19 focuses through the optical disk drive controller 14. The drive current to the coil 34 and tracking coils 35a and 35b is servo controlled. Thereby, the current flowing through the focusing coil 34 acts on the magnetic field by the focusing magnet 37 and the focusing yoke 36 by controlling the drive current of the focusing coil 34, thereby providing a lens holder ( 33 is moved and adjusted in the focusing direction in accordance with the support shaft 32, and focusing is performed. In addition, the drive current of the tracking coils 35a and 35b is controlled so that the current flowing in the directions indicated by arrows M and N in FIG. 12 acts on the magnetic field by the tracking magnet 39 and the tracking yoke 38. The lens holder 33 is rotated around the support shaft 32 on the basis of the second midpoint position, and the objective lens 26a is moved and adjusted in a substantially tangential tracking direction, so that tracking can be performed. Is done.

When the lens holder 33 is moved from the second center position to the first center position again, the current or voltage value applied to the tracking coils 35a and 35b is set in the direction of the arrow M in FIG. ) Will move a greater distance than the tracking stroke for the tracking servo. As a result, the current flowing through the tracking coils 35a and 35b acts on the magnetic field by the tracking magnet 39 and the tracking yoke 38 so that the lens holder 33 rotates around the support shaft 32. The iron piece 41 mounted on the lens holder 33 faces the boundary 39c of the tracking coil 39. As a result, the lens holder 33 moves to the first intermediate position to insert the objective lens 26a into the optical path.

As described above, in the above-described embodiment, the lens holder of the two-axis actuator is swung around the support shaft, whereby one of the plurality of objective lenses is inserted in the optical path, and the objective lens corresponding to the optical disc to reproduce the signal is obtained. Used. As a result, since the light beam from the light source is accurately formed on the signal recording surface of the optical disk through the objective lens, the return light from the signal recording surface of the optical disk is incident on the photodetector, whereby an optimal signal is obtained for a plurality of different types of optical disks. Playback is performed.

Further, the insertion operation of each objective lens into the optical path is realized by the rotation of the lens holder around the support shaft by the interaction of the pair of tracking coils arranged in the lens holder with the tracking magnets fixedly arranged. With a simple configuration, it is possible to switch the objective lens corresponding to the format of the optical disc to be reproduced at low cost.

In addition, the lens holder 33 according to the above embodiment of the optical pickup device has a structure in which the granular mirror 24 is close to the focusing coil and is disposed below the flange 102, so that the thickness of the pickup device itself is increased. Can be reduced.

In the optical disk apparatus 10 and the biaxial actuator 30 according to the above embodiment, the magnetic pole 39a of the tracking magnet 39 is set to the S pole and the magnetic pole 39b to the N pole. It may be polar. In this case, if the direction of the current flowing through the tracking coils 35a and 35b is reversed, the lens holder 33 is similarly tracked at the first midpoint position and the second midpoint position, respectively. .

In addition, in the optical disk apparatus 10 and the biaxial actuator 30 according to the embodiment, two objective lenses 26a and 26b are supported by the lens holder 33, but not limited thereto. It is apparent that more than one objective lens is supported and the objective lenses may be selectively inserted into the optical path depending on the interaction between the tracking coil 35 and the tracking magnet 39.

As described above, according to the present invention, the optical disc of any type can be accurately reproduced by switching to the corresponding objective lens by a simple configuration.

Claims (14)

A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means disposed on the base plate, the magnetic generating means fixedly disposed to face the focusing coil and the tracking coil, respectively. Made of The magnetic generating means includes a first magnet disposed opposite the focusing coil and a second magnet disposed opposite the tracking coil, The lens holder has at least two magnetic bodies in the vicinity of the tracking coil to be attracted by the second magnet. 2-axis actuator. A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means disposed on the base plate, the magnetic generating means fixedly disposed to face the focusing coil and the tracking coil, respectively. Made of The magnetic generating means includes a first magnet disposed opposite the focusing coil and a second magnet disposed opposite the tracking coil, Corresponding to the operating position of the objective lens is inserted into the optical path, a plurality of center positions are disposed in the rotational direction of the lens holder, the center position of the lens holder is switched by the interaction of the tracking coil and the second magnet The objective lens is selectively inserted into the optical path of the lens holder. 2-axis actuator. A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means disposed on the base plate, the magnetic generating means fixedly disposed to face the focusing coil and the tracking coil, respectively. Made of The magnetic generating means includes a first magnet disposed opposite the focusing coil and a second magnet disposed opposite the tracking coil, The second magnet is disposed opposite to the tracking coil, and the S pole and the N pole are magnetized adjacently. 2-axis actuator. A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means disposed on the base plate, the magnetic generating means fixedly disposed to face the focusing coil and the tracking coil, respectively. Made of The lens holder has a cylindrical surface for mounting the flange portion and the focusing coil, the flange portion has an upper surface for mounting the objective lens and a side for mounting the tracking coil 2-axis actuator. A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, the lens holder being opposed to a recording medium and equipped with a first portion suitable for disposing a plurality of objective lenses and a second coil for focusing. A lens holder having a portion and a third portion for mounting the tracking coil, A plurality of objective lenses mounted on the first portion at the same distance from the support shaft, A focusing coil mounted on a second portion of the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to a third portion of the lens holder to drive the lens holder in a tracking direction; A first magnet mounted to the base plate to face the coil for focusing, and A second magnet mounted to the base plate to face the tracking coil Made up of The objective lens is disposed on the lens holder and selectively inserted into the optical path of the laser beam, The lens holder has at least two magnetic bodies in the vicinity of the tracking coil to be attracted by the second magnet. 2-axis actuator. A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, the lens holder being opposed to a recording medium and equipped with a first portion suitable for disposing a plurality of objective lenses and a second coil for focusing. A lens holder having a portion and a third portion for mounting the tracking coil, A plurality of objective lenses mounted on the first portion at the same distance from the support shaft, A focusing coil mounted on a second portion of the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to a third portion of the lens holder to drive the lens holder in a tracking direction; A first magnet mounted to the base plate to face the coil for focusing, and A second magnet mounted to the base plate to face the tracking coil Made up of The objective lens is disposed on the lens holder and selectively inserted into the optical path of the laser beam, The second magnet is disposed opposite to the tracking coil, and the S pole and the N pole are magnetized adjacently. 2-axis actuator. A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, the lens holder being opposed to a recording medium and equipped with a first portion suitable for disposing a plurality of objective lenses and a second coil for focusing. A lens holder having a portion and a third portion for mounting the tracking coil, A plurality of objective lenses mounted on the first portion at the same distance from the support shaft, A focusing coil mounted on a second portion of the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to a third portion of the lens holder to drive the lens holder in a tracking direction; A first magnet mounted to the base plate to face the coil for focusing, and A second magnet mounted to the base plate to face the tracking coil Made up of The objective lens is disposed on the lens holder and selectively inserted into the optical path of the laser beam, Corresponding to the operation position of the objective lens is inserted into the optical path, a plurality of midpoint positions are disposed in the rotational direction of the lens holder, the midpoint position of the lens holder by the interaction of the tracking coil and the second magnet Switched 2-axis actuator. A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, the lens holder being opposed to a recording medium and equipped with a first portion suitable for disposing a plurality of objective lenses and a second coil for focusing. A lens holder having a portion and a third portion for mounting the tracking coil, A plurality of objective lenses mounted on the first portion at the same distance from the support shaft, A focusing coil mounted on a second portion of the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to a third portion of the lens holder to drive the lens holder in a tracking direction; A first magnet mounted to the base plate to face the coil for focusing, and A second magnet mounted to the base plate to face the tracking coil Made up of The objective lens is disposed on the lens holder and selectively inserted into the optical path of the laser beam, The magnetic material is disposed in the vicinity of the tracking coil mounted on the lens holder, the magnet is divided by a boundary line parallel to the support shaft, and the S pole and the N pole are magnetized adjacently. It is maintained in the opposite position about the boundary of the magnet 2-axis actuator. A support shaft disposed on the base plate perpendicular to the signal recording surface of the recording medium, A lens holder slidable along the support shaft and rotatably supported around the support shaft, the lens holder being opposed to a recording medium and equipped with a first portion suitable for disposing a plurality of objective lenses and a second coil for focusing. A lens holder having a portion and a third portion for mounting the tracking coil, A plurality of objective lenses mounted on the first portion at the same distance from the support shaft, A focusing coil mounted on a second portion of the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to a third portion of the lens holder to drive the lens holder in a tracking direction; A first magnet mounted to the base plate to face the coil for focusing, and A second magnet mounted to the base plate to face the tracking coil Made up of The objective lens is disposed on the lens holder and selectively inserted into the optical path of the laser beam, The lens holder has a flange portion and a cylindrical portion, the flange portion has a first portion for mounting the objective lens and a third portion parallel to the optical axis of the objective lens, and for mounting the tracking coil. The part has a second part for mounting the focusing coil. 2-axis actuator. Drive means for rotating the optical disc, A light source for irradiating laser light, An objective lens for irradiating the optical disk with laser light irradiated by the light source, A two-axis actuator for movably supporting the objective lens in a focusing direction and a tracking direction, Photodetector means for detecting the feedback laser light irradiated onto and reflected from the optical disc; Servo means for moving the objective lens supported by the two-axis actuator in the focusing direction and the tracking direction according to the detection signal from the photodetector means, and Moving means for moving the two-axis actuator along the radial direction of the optical disc Made of The two-axis actuator, A support shaft disposed on the base plate perpendicular to the signal recording surface of the optical disc, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means fixedly disposed on the base plate to face the focusing coil and the tracking coil, respectively. And The objective lens is selectively moved in the optical path of the laser light, The magnetic generating means has a first magnet disposed opposite the focusing coil and a second magnet disposed opposite the tracking coil, The lens holder has at least two magnetic bodies in the vicinity of the tracking coil to be attracted by the second magnet. An optical disc apparatus for recording and / or playing an optical disc. Drive means for rotating the optical disc, A light source for irradiating laser light, An objective lens for irradiating the optical disk with laser light irradiated by the light source, A two-axis actuator for movably supporting the objective lens in a focusing direction and a tracking direction, Photodetector means for detecting the feedback laser light irradiated onto and reflected from the optical disc; Servo means for moving the objective lens supported by the two-axis actuator in the focusing direction and the tracking direction according to the detection signal from the photodetector means, and Moving means for moving the two-axis actuator along the radial direction of the optical disc Made of The two-axis actuator, A support shaft disposed on the base plate perpendicular to the signal recording surface of the optical disc, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means fixedly disposed on the base plate to face the focusing coil and the tracking coil, respectively. And The objective lens is selectively moved in the optical path of the laser light, The magnetic generating means has a first magnet disposed opposite the focusing coil and a second magnet disposed opposite the tracking coil, The second magnet is disposed opposite to the tracking coil, and the S pole and the N pole are magnetized adjacently. An optical disc apparatus for recording and / or playing an optical disc. Drive means for rotating the optical disc, A light source for irradiating laser light, An objective lens for irradiating the optical disk with laser light irradiated by the light source, A two-axis actuator for movably supporting the objective lens in a focusing direction and a tracking direction, Photodetector means for detecting the feedback laser light irradiated onto and reflected from the optical disc; Servo means for moving the objective lens supported by the two-axis actuator in the focusing direction and the tracking direction according to the detection signal from the photodetector means, and Moving means for moving the two-axis actuator along the radial direction of the optical disc Made of The two-axis actuator, A support shaft disposed on the base plate perpendicular to the signal recording surface of the optical disc, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means fixedly disposed on the base plate to face the focusing coil and the tracking coil, respectively. And The objective lens is selectively moved in the optical path of the laser light, The magnetic generating means has a first magnet disposed opposite the focusing coil and a second magnet disposed opposite the tracking coil, Corresponding to the operation position of the objective lens is inserted into the optical path, a plurality of mid-point positions are disposed in the rotational direction of the lens holder, the mid-point position of the lens holder is the tracking coil and the second according to the large bull lens used; Switched by the interaction of magnet An optical disc apparatus for recording and / or playing an optical disc. Drive means for rotating the optical disc, A light source for irradiating laser light, An objective lens for irradiating the optical disk with laser light irradiated by the light source, A two-axis actuator for movably supporting the objective lens in a focusing direction and a tracking direction, Photodetector means for detecting the feedback laser light irradiated onto and reflected from the optical disc; Servo means for moving the objective lens supported by the two-axis actuator in the focusing direction and the tracking direction according to the detection signal from the photodetector means, and Moving means for moving the two-axis actuator along the radial direction of the optical disc Made of The two-axis actuator, A support shaft disposed on the base plate perpendicular to the signal recording surface of the optical disc, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means fixedly disposed on the base plate to face the focusing coil and the tracking coil, respectively. And The objective lens is selectively moved in the optical path of the laser light, The magnetic generating means has a first magnet disposed opposite the focusing coil and a second magnet disposed opposite the tracking coil, A magnetic material is disposed in the vicinity of the tracking coil mounted on the lens holder, and the magnet is divided by a boundary line parallel to the support shaft so that the S pole and the N pole are magnetized adjacent to each other. 2 is maintained at the position opposite to the boundary of the magnet An optical disc apparatus for recording and / or playing an optical disc. Drive means for rotating the optical disc, A light source for irradiating laser light, An objective lens for irradiating the optical disk with laser light irradiated by the light source, A two-axis actuator for movably supporting the objective lens in a focusing direction and a tracking direction, Photodetector means for detecting the feedback laser light irradiated onto and reflected from the optical disc; Servo means for moving the objective lens supported by the two-axis actuator in the focusing direction and the tracking direction according to the detection signal from the photodetector means, and Moving means for moving the two-axis actuator along the radial direction of the optical disc Made of The two-axis actuator, A support shaft disposed on the base plate perpendicular to the signal recording surface of the optical disc, A lens holder slidable along the support shaft and rotatably supported around the support shaft, A plurality of objective lenses disposed in the lens holder, A focusing coil mounted on the lens holder to drive the lens holder in a focusing direction; A tracking coil mounted to the lens holder to drive the lens holder in a tracking direction; Magnetic generating means fixedly disposed on the base plate to face the focusing coil and the tracking coil, respectively. And The objective lens is selectively moved in the optical path of the laser light, The lens holder has a flange portion and a cylindrical portion, the flange portion is disposed in parallel to the upper surface for mounting the objective lens and the optical axis of the objective lens, and has a side for mounting the tracking coil, the cylindrical portion for the focusing With cylindrical surface to mount coil An optical disc apparatus for recording and / or playing an optical disc.