JP2003196862A - Objective lens driving device, optical pickup device and recording and/or reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the sliding property between a holder for holding an objective lens and a supporting shaft 13 for slidably supporting this holder. <P>SOLUTION: The device is provided with a base 51 having the supporting shaft 53 arranged thereon and the lens holder 52 whereon a shaft hole 58 to be inserted by the supporting shaft 53 is arranged in almost parallel to an optical axis of the objective lens 14, while holding the objective lens 14, then the lens holder 52 is slid to the axial direction of the supporting shaft 53 by a magnet 55 arranged at the side of the base 51, and a focusing coil 60 and a tracking coil 61 arranged at the side of the lens holder 52, and also the supporting shaft 53 is made to slightly oscillate by an electro-mechanical conversion element 56 arranged on the base 51 when the lens holder 52 is turned around the supporting shaft 53, then the frictional force generated between the shaft hole 58 of the lens holder 52 and the supporting shaft 53 is lowered. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device for displacing an objective lens in a direction parallel to the optical axis and a direction orthogonal to the optical axis. The present invention also relates to an optical pickup device including such an objective lens driving device, and recording and / or recording including such an optical pickup device.
Or, it relates to a reproducing device.

[0002]

2. Description of the Related Art Conventionally, in an optical pickup device mounted on an optical disk device, a magneto-optical disk device, or the like, an objective lens driving device displaces the objective lens in a focusing direction parallel to the optical axis of the optical disk device. Focusing operation of focusing the objective lens on the signal recording surface and displacing the objective lens in the tracking direction orthogonal to the optical axis of the objective lens so that the spot of the light beam focused by the objective lens follows the recording track of the optical disc. Performs tracking operation.

As such an objective lens driving device,
For example, there is a shaft sliding type biaxial actuator. This biaxial actuator includes a base provided with a support shaft, a lens holder that holds an objective lens at one end side thereof, and has a shaft hole through which the support shaft is inserted, provided in parallel with the optical axis of the objective lens. ing. The biaxial actuator also includes a pair of magnets on the base side and a focusing coil and a tracking coil on the lens holder side. In this biaxial actuator, the support shaft is inserted into the shaft hole of the lens holder, so that the lens holder is supported slidably in the axial direction of the support shaft and around the shaft, and the pair of magnets and focusing coil are provided. And the tracking coil are arranged to face each other at a predetermined interval. Further, a balancer for balancing the weight of the objective lens around the support shaft is arranged on the other end side of the lens holder.

In the biaxial actuator constructed as described above, when a driving current corresponding to the focus error signal is supplied to the focusing coil, the lens holder acts on the spindle by the action of the magnetic field generated by the pair of magnets. Is axially slid. This allows the above-mentioned focusing operation to be performed while displacing the objective lens in the focusing direction.

On the other hand, in this biaxial actuator, when a drive current corresponding to a tracking error signal is supplied to the tracking coil, the lens holder is rotated around the axis of the support shaft by the action of the magnetic field generated by the pair of magnets. Be moved. As a result, the above-described tracking operation can be performed while displacing the objective lens in the tracking direction.

Further, in this biaxial actuator, the balancer optimizes the weight balance with the objective lens centered on the support shaft, thereby improving the earthquake resistance and preventing the inclination of the objective lens with respect to the optical disc. Has been done.

[0007]

By the way, in the above-mentioned shaft sliding type biaxial actuator, the lens holder is supported so as to be slidable in the axial direction of the support shaft and is rotatable about the support shaft. Since it is supported, its performance depends on the sliding characteristics of the lens holder and the support shaft.

Specifically, in this biaxial actuator, when there is rattling between the shaft hole of the lens holder and the support shaft, the tilt of the lens holder becomes large, and the rattling is suppressed in order to suppress the tilt. If it is made smaller, the sliding characteristics between the lens holder and the support shaft deteriorate due to catching or the like, and it becomes difficult to appropriately displace the objective lens in the focusing direction and the tracking direction described above.

In order to solve this problem, in the conventional biaxial actuator, for example, the driving voltage applied to the focusing coil and the tracking coil is set to 1
A method has been proposed in which a low-frequency signal of about 00 Hz is input and the lens holder is slightly vibrated to improve sliding characteristics between the lens holder and the support shaft.

However, in the axial sliding type biaxial actuator, even if the sliding characteristic between the lens holder and the support shaft is improved by using such a method, the effect is not always sufficient, and particularly, the effect is not sufficient. When the size is reduced, the focusing coil, the tracking coil, and the like are also reduced, so that the driving force generated in the focusing coil and the tracking coil is also reduced. In this case, while applying a minute vibration to the lens holder by the focusing coil and the tracking coil,
It becomes more difficult to properly displace the objective lens in the focusing direction and the tracking direction.

Therefore, the present invention has been proposed in view of such conventional circumstances, and shows the sliding characteristics of a holder for holding an objective lens and a support shaft for slidably supporting the holder. It is an object of the present invention to provide an objective lens driving device that can be significantly improved.

Further, according to the present invention, by including such an objective lens driving device, the focusing operation for focusing the objective lens on the signal recording surface of the optical disk and the spot of the light beam condensed by the objective lens are performed. An object of the present invention is to provide an optical pickup device capable of appropriately performing a tracking operation of following a recording track of an optical disc.

It is another object of the present invention to provide a recording and / or reproducing apparatus capable of appropriately recording and / or reproducing a signal on an optical disc by including such an optical pickup. To do.

[0014]

In order to achieve this object, an objective lens driving device according to the present invention has a base provided with a support shaft and an axis through which the support shaft is inserted while holding the objective lens. A first holder that slides the holder in the axial direction of the support shaft by a holder provided with a hole substantially parallel to the optical axis of the objective lens, a magnet provided on the base side, and a coil provided on the E side. A driving force generating means for generating a driving force and a second driving force for rotating the holder around the axis of the support shaft; and an electromechanical conversion element provided on the base for vibrating the support shaft. I am trying.

As described above, in the objective lens driving device according to the present invention, the electromechanical conversion element vibrates the support shaft, whereby the frictional force generated between the support shaft and the shaft hole of the holder decreases. The sliding characteristics between the holder and the spindle are improved. Accordingly, the holder can be appropriately slid in the axial direction of the support shaft and can be appropriately rotated around the shaft of the support shaft.

Further, the optical pickup device according to the present invention includes a light source for emitting a light beam, an objective lens for condensing the light beam emitted from the light source on a signal recording surface of the optical disc, and a reflection on the signal recording surface of the optical disc. A light detecting means for receiving the returned return light beam, and an objective lens driving device for displacing the objective lens in the focusing direction and the tracking direction with respect to the optical disc based on the detection signal detected by the light detecting means. Prepare The objective lens driving device includes a base provided with a support shaft, a holder for holding the objective lens, a holder having a shaft hole through which the support shaft is inserted and substantially parallel to the optical axis of the objective lens, and a base. The magnet provided on the side of the holder and the coil provided on the side of the holder to slide the holder in the axial direction of the support shaft.
Drive force generating means for generating a second drive force for rotating the holder about the axis of the support shaft, and an electromechanical conversion element provided on the base for vibrating the support shaft. It has a feature.

As described above, in the optical pickup device according to the present invention, the sliding characteristic between the holder and the support shaft in the objective lens driving device is improved, so that the objective lens is moved in the focusing direction and the tracking direction with respect to the optical disk. A focusing operation for focusing the objective lens on the signal recording surface of the optical disc and a tracking operation for making the spot of the light beam focused by the objective lens follow the recording track of the optical disc. It can be done properly.

Further, the recording and / or reproducing apparatus according to the present invention records and / or reproduces a signal on / from a disk rotation driving means for rotationally driving the optical disk and an optical disk rotationally driven by the disk rotation driving means. The optical pickup device includes: an optical pickup device; a supporting unit that supports the optical pickup device so as to be movable in the radial direction of the optical disc; and a drive unit that moves the optical pickup device supported by the supporting unit in the radial direction of the optical disc. Then, the optical pickup device includes a light source that emits a light beam, an objective lens that focuses the light beam emitted from the light source on the signal recording surface of the optical disc, and a return light beam that is reflected by the signal recording surface of the optical disc. An objective lens driving device having a light detecting means for receiving light and an objective lens driving device for displacing the objective lens in the focusing direction and the tracking direction with respect to the optical disc based on the detection signal detected by the light detecting means. Is a holder provided with a base provided with a support shaft and an objective lens, a shaft hole through which the support shaft is inserted being provided substantially parallel to the optical axis of the objective lens, and a magnet provided on the base side. And the coil provided on the holder side,
A drive force generating unit that generates a first drive force that slides the holder in the axial direction of the support shaft and a second drive force that rotates the holder around the support shaft is provided on the base. And an electromechanical conversion element that vibrates the.

As described above, in the recording and / or reproducing apparatus according to the present invention, the sliding characteristic between the holder and the support shaft in the objective lens driving device is improved, and the focusing operation and the tracking operation by the optical pickup device are properly performed. As a result, the recording and / or reproducing of the signal on the optical disc can be appropriately performed.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An example in which the present invention is applied to a disc player for reproducing an information signal from an optical disc will be described in detail below with reference to the drawings.

The disc player 1 shown in FIG. 1 has a disc rotation drive mechanism 3 for rotationally driving the optical disc 2 in the direction indicated by an arrow A in FIG. 1, and an optical disc 2 rotationally driven by the disc rotation drive mechanism 3. An optical pickup device 4 for reproducing an information signal, a support mechanism 5 for movably supporting the optical pickup device 4 in a radial direction of an optical disc 2 shown by an arrow B in the figure, and an optical pickup supported by the support mechanism 5. A drive mechanism 6 for moving the device 4 in the radial direction of the optical disk 2 is provided, and these are mounted on a mechanical chassis 7.

The disk rotation drive mechanism 3 is used for the optical disk 2
It has a disk table 8 on which is mounted, and a spindle motor 9 for rotationally driving the disk table 8.

The disk table 8 has a mounting surface 8a on which the optical disk 2 is mounted, and the mounting surface 8a is arranged so that the frictional force with the mounted optical disk 2 becomes large. A sheet-shaped rubber member 10 formed in an annular shape is attached. Further, at the center of rotation of the disc table 8, a center cap 11 that is fitted into the center hole 2a of the optical disc 2 mounted on the mounting surface 8a is provided so as to project. A plurality of chuck claws 1 for holding the fitted optical disk 2 on the mounting surface 8a of the disk table 8 are provided on the outer peripheral portion of the center cap 11.
Two are provided.

The center portion of the disk table 8 is attached to the rotary shaft 9a of the spindle motor 9, so that the disk table 8 is rotationally driven in the direction indicated by arrow A in FIG.

The optical pickup device 4 has, inside the case 13, a semiconductor laser which is a light source for emitting a light beam to the optical disc 2, a grating for splitting the light beam emitted from the semiconductor laser, and this grating. A beam splitter arranged in the optical path of the passed light beam, a collimator lens that collimates the light beam that has passed through this beam splitter, and a light beam that is collimated by this collimator lens. And a return mirror which reflects on the signal recording surface of the optical disc 2 and an objective lens 14 which focuses the light beam reflected by the raising mirror on the signal recording surface of the optical disc 2. An optical block having a photodetector for receiving light, and a detection signal detected by the photodetector Based on, and an objective lens driving device for displacing the objective lens 14 in the tracking direction perpendicular to the optical axis of the optical axis and parallel to Four cut single direction and the objective lens of the objective lens 14. Of these, only the objective lens 14 is structured so as to face outward from the opening 15 formed in the case 13.

The support mechanism 5 has a support base 16 for supporting the optical pickup device 4, and a guide shaft 17 for movably supporting the support base 16 in the radial direction of the optical disc 2.

Further, the mechanical chassis 7 is formed with an opening 7a through which the optical pickup device 4 supported by the support base 16 is exposed. The opening 7a is formed in a substantially rectangular shape along the radial direction of the optical disc 2,
The optical pickup device 4 is exposed outside over the movable range, that is, the inner and outer circumferences of the optical disc 2.

The support base 16 is arranged so that the optical pickup device 4 faces outward from the opening 7a. Then, of the side edge portions of the support base 16 located in the direction orthogonal to the radial direction of the optical disc 2, one side edge portion has a support portion 19 in which a guide hole 18 for inserting the guide shaft 17 is formed. Are integrally formed with each other, and a pair of supporting piece portions 20 sandwiching the end edge portion of the mechanical chassis 7 forming the opening portion 7a are formed on the other side edge portion so as to project in the opposite direction to the supporting portion 19. There is.

The guide shaft 17 is arranged in parallel with the radial direction of the optical disk 2, and both ends of the guide shaft 17 are screwed around the opening 7a of the mechanical chassis 7 while being inserted into the guide holes 18 of the supporting portion 19. It is fixedly supported by means of stoppers.

Therefore, the support base 16 has the support portion 1
9 is slidably supported along the guide shaft 17, and the pair of support piece portions 20 is slidably supported along the end edges of the mechanical chassis 7, so that the optical disc shown by the arrow B in FIG. 2 is supported so as to be movable in the radial direction.

The drive mechanism 6 includes a drive motor 21 attached to the mechanical chassis 7, a first gear 22 attached to a rotary shaft 21a of the drive motor 21, and a first gear 22 meshed with the first gear 22. Second gear 23, a third gear 24 coaxially supported by the second gear 23, a fourth gear 25 meshed with the third gear 24, and a support portion 19 of the support base 16. And a rack portion 26 meshed with the fourth gear 25, and the rack portion 26 is
It is formed along the axial direction of the guide shaft 17. Also,
The second to fourth gears 23, 24, 25 are rotatably supported by the mechanical chassis 7 via support shafts 27, 28.

In this drive mechanism 6, when the drive motor 21 is rotationally driven, the drive force of the drive motor 21 is adjusted by the first to fourth gears 22, 23, 24, 25 meshing with each other, and the fourth Rack portion 26 meshed with the gear 25 of
Will move along the guide shaft 17. As a result, the support base 16 can be moved together with the optical pickup device 4 in the radial direction of the optical disc 2 shown by the arrow B in FIG.

In the disc player 1 configured as described above, when the optical disc 2 placed on the placement surface 8a of the turntable 8 is rotationally driven by the spindle motor 9, the support base 16 is moved by the drive mechanism 6. The optical pickup device 4 reproduces an information signal with respect to the optical disc 2 while the optical pickup device 4 is being fed in the radial direction of the optical disc 2.

Specifically, the optical pickup device 4 focuses the light beam emitted from the light source by the objective lens 14 and irradiates the signal recording surface of the optical disc 2 with the light beam, and is reflected by the signal recording surface of the optical disc 2. The returning light beam is received by the photodetector. Then, the information signal recorded on the optical disc 2 is reproduced based on the detection signal detected by the photodetector.

In the optical pickup device 4, the objective lens driving device displaces the objective lens 14 in the focusing direction based on the detection signal detected by the photodetector, and the objective lens is formed on the signal recording surface of the optical disc 2. 1
The focusing operation for focusing the light beam 4 and the tracking operation for causing the spot of the light beam focused by the objective lens 14 to follow the recording track of the optical disc 2 while displacing the objective lens 14 in the tracking direction are performed.

An objective lens driving device to which the present invention is applied is, for example, a shaft sliding type biaxial actuator 50 shown in FIGS. 2, 3 and 4, and the biaxial actuator 50 serves as a fixed portion. A base 51 and a lens holder 52 that holds the above-described objective lens 14 and that serves as a movable portion for the base 51 are provided.

The base 51 is made of a magnetic material, and a support shaft 53 which is substantially perpendicular to the main surface is erected at a substantially central portion thereof. The support shaft 53 is made of a magnetic material and is attached to the base 51 by press fitting or caulking.

A support shaft 53 is provided at both ends of the base 51.
A pair of yokes 54a and 54b that are opposed to each other with the pinch in between are erected. The pair of yokes 54a and 54b are made of a magnetic material integrally formed with the base 51, and the pair of magnets 55a and 55b are attached to the surfaces facing each other. The pair of magnets 55a and 55b are
The magnets are magnetized so that the magnetic poles on the surfaces facing each other are the same, that is, the N poles or the S poles face each other. Here, the pair of magnets 55a and 55b are arranged so as to face each other so that their S poles face each other.

A pair of mounting pieces 57, 5 for mounting the electromechanical conversion element 56 are provided at both ends of the base 51.
7 is provided extending in a direction substantially orthogonal to the base 51 in the same plane as the base 51. Then, the electromechanical conversion element 56 includes the pair of mounting pieces 57, 57.
It is attached by an adhesive or the like in a state of being hung between the tip portions of the.

The electromechanical conversion element 56 is composed of a piezoelectric element and expands and contracts when a high frequency signal of, for example, about 30 kHz is supplied, and the base 5 is attached via a pair of mounting pieces 57, 57.
The support shaft 53 provided in No. 1 is slightly vibrated.

The lens holder 52 is formed by molding a material having a high rigidity and a low frictional resistance such as a liquid crystal polymer so that the lens holder 52 slides smoothly on the support shaft 53. In addition, a cylindrical portion 59 having a shaft hole 58 through which the support shaft 53 is inserted is provided at a substantially central portion of the lens holder 52.

The tubular portion 59 is formed so as to project in a direction shorter than the support shaft 53 in a direction orthogonal to the lens holder 52. A focusing coil 60 is wound around and attached to the outer peripheral portion of the tubular portion 59. Further, on the outer peripheral portion of the focusing coil 60, the first to fourth tracking coils 61a, 61b, 61 are provided.
c and 61d are attached such that the winding center thereof is orthogonal to the central axis S _{1 of the} shaft hole 58. Of these, the first and second tracking coils 61a and 61b and the third and fourth tracking coils 61c and 61d are the center of the objective lens 14 and the center of the shaft hole 58 in the outer peripheral portion of the focusing coil 60. Are arranged at positions symmetrical with respect to a straight line (corresponding to a line segment XX ′ shown in FIG. 2) connecting between and so as to be aligned in the winding direction of the focusing coil 60.

The lens holder 52 is slidably supported in the axial direction of the support shaft 53 by inserting the support shaft 53 into the shaft hole 58 of the cylindrical portion 59, and the shaft of the support shaft 53 is also supported. It is rotatably supported around. Also,
By inserting the support shaft 53 into the shaft hole 58 of the tubular portion 59, the first and second tracking coils 61a,
61b and one magnet 55a are arranged to face each other at a predetermined interval, and the third and fourth tracking coils 61c and 61d and the other magnet 55b are arranged to face each other at a predetermined interval.

Further, these focusing coils 60
And the first to fourth tracking coils 61a, 61
b, 61c, 61d are electrically connected to the base 51 side via a flexible wiring 62. The flexible wiring 62 applies a drive current controlled by an external servo control circuit to the focusing coil 60 and the first to fourth tracking coils 61a, 61b, 61c, 6.
In order to supply 1d, it has sufficient flexibility and length that does not hinder the movement of the lens holder 52.

A lens mounting portion 63 for mounting the objective lens 14 is provided on one end of the lens holder 52. A holder hole 63a into which the objective lens 14 is fitted is formed at the tip of the lens mounting portion 63, and the center axis S _{1 of the} shaft hole 58 and the optical axis S of the objective lens 14 are formed in the holder hole 63a. _The objective lens 14 is held so that ₂ and ₂ are parallel to each other.

On the other end side of the lens holder 52, there is provided a balancer mounting portion 65 to which a balancer 64 for balancing the weight of the objective lens 14 mounted on the lens mounting portion 63 is mounted. The balancer mounting portion 65 is bent from the end of the tubular portion 59 on the lens holder 52 side toward the end on the opposite side, and the tip of the balancer mounting portion 65 projects in the opposite direction to the lens mounting portion 63. It has a shape. The balancer 64 is formed in a rod shape and is attached along the tip of the balancer attachment portion 65. As a result, the weight balance and the moment when the lens holder 52 moves are optimized.

Further, the biaxial actuator 50 includes
A neutral ring 66 for holding the lens holder 52 at a neutral position in the focusing direction and the tracking direction with respect to the support shaft 53 is provided. In addition, a pair of yokes 54 a,
A cover 67 is provided between 54b.

In the biaxial actuator 50 configured as described above, as shown in FIGS. 5 and 6, based on the detection signals such as the focus error signal and the tracking error signal detected by the photodetector described above, The servo control circuit controls the drive current supplied to the focusing coil 60 and the first to fourth tracking coils 61a, 61b, 61c, 61d, so that the objective lens 14 moves in the focusing direction and the tracking direction with respect to the optical disc 2. Displace in the direction.

Specifically, in this biaxial actuator 50, the focusing coil 60 and the first to fourth tracking coils 61a, 61b, 61c, 61 are stopped when the optical disk 2 is not irradiated with the light beam.
No drive current is supplied to d. In this case, in the lens holder 52, the neutral ring 66 has a pair of magnets 55a, 5a.
It is magnetically attracted to the position of 5b having the highest magnetic flux density, and is held at a neutral position in the focusing direction and the tracking direction.

When a driving current in the direction indicated by arrow I in FIG. 5 is supplied to the focusing coil 60, a magnetic field is generated in the pair of magnets 55a and 55b (indicated by an arrow in FIG. 6). ), The focusing coil 60 receives an external force in the direction indicated by arrow F in FIG. In addition, this focusing coil 60
On the other hand, when the driving current in the direction opposite to the direction shown by the arrow I in FIG.
Receives an external force in the direction opposite to the direction indicated by arrow F in FIG.

Therefore, the lens holder 52 includes the pair of magnets 55a, 55b and the focusing coil 6.
The driving force in the focusing direction generated by 0 and 0 causes the support shaft 53 to slide in the axial direction, and accordingly, the objective lens 14 is displaced in the focusing direction.

Further, in this biaxial actuator 50,
When the lens holder 52 is slid in the axial direction of the support shaft 53, the electromechanical conversion element 56 described above causes the support shaft 53 to slightly vibrate. Thereby, the shaft hole 58 of the lens holder 52
The frictional force generated between the support shaft 53 and the support shaft 53 is reduced. Therefore, in the biaxial actuator 50, the sliding characteristic between the lens holder 52 and the support shaft 53 is improved, so that the objective lens 14 can be appropriately displaced in the focusing direction.

In the lens holder 52, when the supply of the drive current to the focusing coil 60 is stopped, the neutral ring 66 is magnetically attracted to the position where the magnetic flux density of the pair of magnets 55a and 55b is the highest. , Is returned to the neutral position in the focusing direction again.

On the other hand, for the first to fourth tracking coils 61a, 61b, 61c and 61d, for example, as shown in FIG.
When the drive currents in the directions indicated by the middle arrows I ₁ , I ₂ , I ₃ , and I ₄ are supplied, the action with the magnetic field (indicated by the arrow in FIG. 6) generated in one of the magnets 55a is caused.
First and second tracking coils 61a, with 61b receives an external force in the direction shown in FIG. 5 arrow F _'1, by the action of the magnetic field (. Indicated by the arrow in FIG. 6) that occur in the other magnet 55b , third and fourth tracking coils 61c, 61d is subjected to an external force in the direction shown in FIG. 5 arrow F _'2.

The direction I ₁ of the drive current supplied to the first tracking coil 61a and the direction I _{2 of the} drive current supplied to the second tracking coil 61b are opposite to each other, and the third direction is the third direction. The direction I ₃ of the drive current supplied to the tracking coil 61c and the direction I _{4 of the} drive current supplied to the fourth tracking coil 61d are opposite to each other. In addition, the first tracking coil 61a
The direction I ₁ of the driving current supplied to the second tracking coil 61b is the same as the direction I _{4 of the} driving current supplied to the fourth tracking coil 61d.
The direction I ₂ of the drive current supplied to the third tracking coil 61c is the same as the direction I _{3 of the} drive current supplied to the third tracking coil 61c.

A drive current in the direction opposite to the direction indicated by arrows I ₁ , I ₂ , I ₃ , I ₄ in FIG. 5 is applied to the first to fourth tracking coils 61a, 61b, 61c, 61d. When supplied respectively, these first to fourth
Tracking coils 61a, 61b, 61c, 61d
Receives an external force in the direction opposite to the direction indicated by the arrow F ′ in FIG.

Accordingly, the lens holder 52 is supported by the pair of magnets 55a, 55b and the first to fourth tracking coils 61a, 61b, 61c, 61d in the tracking direction by the driving force in the tracking direction. The objective lens 14 is displaced in the tracking direction in accordance with the rotation around the axis.

Further, in this biaxial actuator 50,
When the lens holder 52 is rotated around the axis of the support shaft 53, the electromechanical conversion element 56 described above causes the support shaft 53 to vibrate slightly. As a result, the frictional force generated between the shaft hole 58 of the lens holder 52 and the support shaft 53 is reduced. Therefore, in this biaxial actuator 50, the lens holder 5
Since the sliding characteristic between the support shaft 2 and the support shaft 53 is improved, the objective lens 14 can be appropriately displaced in the tracking direction.

The lens holder 52 includes the first to fourth lenses.
Tracking coils 61a, 61b, 61c, 61d
When the supply of the drive current to the neutral ring 66 is stopped, the neutral ring 66 is magnetically attracted to the position where the magnetic flux density of the pair of magnets 55a and 55b is highest, so that the neutral ring 66 is returned to the neutral position in the tracking direction again.

As described above, in the biaxial actuator 50, the electromechanical conversion element 56 causes the support shaft 53 to vibrate slightly, so that the sliding characteristic between the lens holder 52 and the support shaft 53 can be significantly improved. It is possible.

Here, the drive voltage applied to the focusing coil 60 is increased from 0 V to a plus (+) while the electromechanical conversion element 56 gives a minute vibration to the support shaft 53.
After the voltage was changed to a predetermined voltage value in the negative direction, the voltage was changed to a predetermined voltage value in the negative (-) direction, and the displacement in the focusing direction of the objective lens 14 when the voltage was returned to 0 V was measured. The measurement result is shown in FIG.

For comparison, the objective lens 1 when a driving voltage similar to that shown in FIG. 7 is applied to the focusing coil 60 without applying minute vibration to the support shaft 53.
The displacement of No. 4 in the focusing direction was measured. The measurement result is shown in FIG.

From the measurement results shown in FIGS. 7 and 8,
When no minute vibration is applied to the support shaft 53, as shown in FIG. 8, when the drive voltage applied to the focusing coil 60 is changed, a dead region Z in which the objective lens 14 is not displaced in the focusing direction is formed. You can see that it is occurring.

On the other hand, when minute vibration is applied to the support shaft 53 by the electromechanical conversion element 56, as shown in FIG. 7, it is generated between the shaft hole 58 of the lens holder 52 and the support shaft 53. It can be seen that the generation of the dead zone Z described above is significantly suppressed due to the decrease in the frictional force.

From this also, it is very effective to give the micro-vibration to the support shaft 53 by the electromechanical conversion element 56 in order to improve the sliding characteristic between the lens holder 52 and the support shaft 53.

As described above, in the biaxial actuator 50 to which the present invention is applied, the electromechanical conversion element 56 includes the support shaft 53.
Since the lens is vibrated slightly, compared to the conventional method of inputting a low frequency signal to the driving voltage applied to the focusing coil and the tracking coil to vibrate the lens holder, the focusing coil 60 and the first 1st to 4th tracking coils 61a, 61b,
It is possible to improve the sliding characteristic between the lens holder 52 and the support shaft 53 without being affected by the driving force generated in the 61c and 61d.

Therefore, this biaxial actuator 50 is
Then, even if the lens holder 52 is downsized,
It is possible to appropriately drive and displace the objective lens 14 held in the focusing direction and the tracking direction.

Further, in the above-described optical pickup device 4, by including such a biaxial actuator 50, the objective lens 14 can be appropriately displaced in the focusing direction and the tracking direction. It is possible to appropriately perform the focusing operation of focusing the objective lens 14 on the signal recording surface and the tracking operation of causing the spot of the light beam condensed by the objective lens 14 to follow the recording track of the optical disc 2.

In the disc player 1 described above,
Since the focusing operation and the tracking operation described above are appropriately performed by including the optical pickup device 4 as described above, it is possible to appropriately perform the reproduction of the information signal with respect to the optical disc 2. In particular, it is possible to greatly improve the advantages such as the earthquake resistance and the dynamic skew by taking advantage of the characteristics of the shaft sliding type biaxial actuator 50.

In the disc player 1 described above,
Since the sliding characteristic between the lens holder 52 and the support shaft 53 in the biaxial actuator 50 is improved, the low-range sensitivity of the biaxial actuator 50 is improved, so that the electric power for driving the biaxial actuator 50 is reduced. It is possible to Therefore, this power saving makes it possible to offset the increase in the power required to drive the electromechanical conversion element 56.

In the above-described biaxial actuator 50, in order to improve the sliding characteristics of the lens holder 52 and the support shaft 53, a lubricant may be applied to the surfaces that slide on each other.

The present invention is not limited to the one which reproduces the information signal from the optical disc 2 like the above-mentioned disc player 1, but may be a write-once type or a write type optical disc, a magneto-optical disc. It is also applicable to those capable of recording and reproducing information signals with respect to etc.

[0073]

As described above, in the objective lens driving device according to the present invention, it is possible to improve the sliding characteristic between the holder and the support shaft by vibrating the support shaft by the electromechanical conversion element. The holder can be appropriately slid in the axial direction of the support shaft and can be appropriately rotated around the support shaft.

Further, in the optical pickup device according to the present invention, the sliding characteristic between the holder and the support shaft in the objective lens driving device is improved, and the objective lens can be appropriately displaced in the focusing direction and the tracking direction. Therefore, it is possible to appropriately perform the focusing operation of focusing the objective lens on the signal recording surface of the optical disc and the tracking operation of causing the spot of the light beam condensed by the objective lens to follow the recording track of the optical disc. is there.

Further, in the recording and / or reproducing apparatus according to the present invention, the sliding characteristic between the holder and the support shaft in the objective lens driving device is improved, and the focusing operation and the tracking operation by the optical pickup device are appropriately performed. Therefore, it is possible to appropriately record and / or reproduce the signal on the optical disc.

[Brief description of drawings]

FIG. 1 is a perspective view showing a disc player to which the present invention is applied.

FIG. 2 is a perspective plan view showing a biaxial actuator to which the present invention is applied.

FIG. 3 is a sectional view taken along line X-X ′ in FIG.

4 is a cross-sectional view taken along the line segment Y-Y 'in FIG.

FIG. 5 is a schematic diagram for explaining the operation principle of the biaxial actuator.

FIG. 6 is another schematic view for explaining the operation principle of the biaxial actuator.

FIG. 7 is a characteristic diagram showing the relationship between the driving voltage of the focusing coil and the displacement of the objective lens when minute vibration is applied to the support shaft by the electromechanical conversion element.

FIG. 8 is a characteristic diagram showing the relationship between the driving voltage of the focusing coil and the displacement of the objective lens when minute vibration is not applied to the support shaft.

[Explanation of symbols]

1 disc player, 2 optical disc, 3 disc rotation drive mechanism, 4 optical pickup device, 5 support mechanism, 6 drive mechanism, 7 mechanical chassis, 14 objective lens, 50 biaxial actuator (objective lens drive device), 51 base, 52 lens Holder, 53 support shaft, 54 yoke, 55 magnet, 56 electromechanical conversion element, 58 shaft hole, 59 cylindrical portion, 60 focusing coil, 61 tracking coil, 62 flexible wiring, 63 lens mounting portion, 64 balancer, 65 balancer Mounting part, 66 Neutral ring, 67
cover

Claims (3)

[Claims] 1. A base provided with a support shaft, a holder for holding an objective lens, and a holder provided with an axial hole through which the support shaft is inserted, substantially parallel to an optical axis of the objective lens; A first driving force for sliding the holder in the axial direction of the support shaft and a magnet for rotating the holder around the shaft of the support shaft by a magnet provided on the holder and a coil provided on the holder side. An objective lens driving device comprising: a driving force generating unit that generates the driving force of 2; and an electromechanical conversion element that is provided on the base and vibrates the support shaft. 2. A light source for emitting a light beam, an objective lens for converging the light beam emitted from the light source on a signal recording surface of an optical disc, and a returning light beam reflected by the signal recording surface of the optical disc. Based on the light detection means for receiving light and the detection signal detected by the light detection means,
An objective lens driving device for displacing the objective lens in the focusing direction and the tracking direction with respect to the optical disc is provided, and the objective lens driving device holds a base provided with a support shaft and the objective lens. , The holder having an axial hole through which the support shaft is inserted is provided substantially in parallel with the optical axis of the objective lens, the magnet provided on the base side, and the coil provided on the holder side, thereby holding the holder. The drive force generating means for generating a first drive force for sliding the support shaft in the axial direction and a second drive force for rotating the holder around the support shaft are provided on the base, An optical pickup device having an electromechanical conversion element for vibrating the support shaft. 3. A disc rotation driving means for rotating an optical disc, an optical pickup device for recording and / or reproducing a signal on the optical disc rotated by the disc rotation driving means, and the optical pickup device. The optical pickup device is provided with supporting means for movably supporting the optical disc in the radial direction, and driving means for moving the optical pickup device supported by the supporting means in the radial direction of the optical disc. A light source for emitting light, an objective lens for condensing the light beam emitted from the light source on a signal recording surface of the optical disc, a light detecting means for receiving a returning light beam reflected by the signal recording surface of the optical disc, The objective lens is focused on the optical disc based on the detection signal detected by the light detecting means. An objective lens driving device for displacing in the tracking direction and the tracking direction. The objective lens driving device holds a base provided with a support shaft, and an axis through which the support shaft is inserted while holding the objective lens. The holder is slid in the axial direction of the support shaft by a holder provided with a hole substantially parallel to the optical axis of the objective lens, a magnet provided on the base side, and a coil provided on the holder side. Driving force generating means for generating a first driving force and a second driving force for rotating the holder around the support shaft, and an electromechanical conversion device provided on the base for vibrating the support shaft. A recording and / or reproducing apparatus having an element.