JP2001134964A - Objective lens actuator for optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens actuator capable of driving the objective lens of an optical disk device at high speed in a focus direction, track direction and radial tilt direction and also accurately detecting the position in the track direction and the inclination in the radial direction of the objective lens. SOLUTION: A movable track holder 13 is supported at the tip end of a first elastic supporting member 14 which is projectingly provided from a fixed track holder 12 fixed on a base 10 and which is deformable in the track direction. Also, a lens holder 11 with the objective lens 1 fixed is supported at the tip end of a second elastic supporting member 15 which is projectingly provided from a movable track holder 13 and which is deformable in the focus direction. The lens holder 11 is equipped with plural coil elements 16, 17a, 17b, 20a, 20b, while the base 10 is provided with plural magnets 19a, 19b, 22a-22d corresponding to each coil element. In addition, a track position detecting sensor 25 is arranged opposite to the movable track holder 13, and a tilt sensor 23 is arranged opposite to the lens holder 11, thereby detecting the position in the track direction and inclination in the radial direction of the lens holder 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens actuator for an optical disk device, and more particularly to a high-density optical disk drive capable of following the inclination of the recording surface of the optical disk itself and the fluctuation of the inclination of the recording surface caused by rotation of the optical disk. The present invention relates to an objective lens actuator capable of performing various recording and reproduction.

[0002]

2. Description of the Related Art Conventionally, an optical head of an optical disk device has
For example, a semiconductor laser element as a light emitting source, an objective lens for condensing light from the semiconductor laser element on the recording surface of the optical disk, a focus direction in which the objective lens is perpendicular to the recording surface of the optical disk, and an optical disk Objective lens actuator that is supported movably in two axial directions of the track direction that is the radial direction of the optical disk perpendicular to the track length direction, an optical sensor that detects return light from the optical disk, and detection from the optical sensor There is provided a control circuit for performing so-called focusing control and tracking control for performing drive control of the objective lens actuator in the focus direction and the track direction based on the signal.

An objective lens actuator for performing such control generally includes a lens holder for holding an objective lens so that an optical axis is perpendicular to a recording surface of an optical disc, and a focus direction and a lens holder. An elastic support member movably supports in the track direction, and a base supporting the elastic support member. Further, the lens holder includes a focus coil and a track coil, and a pair of yokes made of a magnetic material and a magnet attached to the yoke are provided on the base so as to face the respective coils. Then, a drive current controlled by the control circuit based on the detection signal of the optical sensor is supplied to each of the coils, so that the magnetic flux generated in each coil and the magnetic flux of the magnet interact with each other. The lens holder is moved in the focus direction and the track direction against the tension of the elastic support member. As a result, the objective lens supported by the lens holder is located at an optimum position for recording and reproduction with respect to the optical disk surface in the focus direction and the track direction.

In such a lens actuator, the allowable range of the inclination between the optical axis of the objective lens and the recording surface of the optical disk is small, and the optical axis of the objective lens held by the lens holder when attached to the optical head. Are accurately adjusted in the radial direction and the tangential direction of the optical disk so as to be within an allowable range with respect to the recording surface of the optical disk, and are fixedly held. However, in recent years, optical discs have been used as external storage media for computers and recording media for audio and video information, in order to record larger amounts of information. In addition, an allowable range for a change in the inclination of the recording surface caused by the rotation of the optical disk has become smaller. In such a high density, the radial inclination is affected by crosstalk from an adjacent track due to the coma generated thereby, and has a significant effect on the quality of a reproduced signal.

Therefore, as a method for solving this inconvenience, Japanese Patent Application Laid-Open No. Hei 1-211248, "Optical Disk Device" and Japanese Patent Application Laid-Open No. Hei 1-307030, "Tilt Adjustment Mechanism of Optical Disk Player" have been proposed. In these techniques, the inclination of the optical disk in the radial direction is detected by a sensor, and the entire optical head including the objective lens actuator is mechanically inclined in accordance with the detected inclination to correct the inclination. However, this prior art,
Since the entire optical head is tilted, the driving weight is large,
The drive mechanism becomes large and complicated, and high frequency response performance cannot be obtained.Therefore, it is possible to follow the tilt due to the gentle and simple warpage of the recording surface from the inner circumference to the outer circumference of the disk, but it can follow the rotation of the optical disk. It is difficult to quickly follow the change in the inclination of the recording surface that occurs.

On the other hand, Japanese Patent Application Laid-Open No. 09-231595 discloses a technique for obtaining such a high frequency response performance.
Japanese Patent Application Laid-Open Publication No. 03-137831 entitled "Optical Disk Apparatus" has been proposed. For example, in the former configuration, the lens holder is supported on the actuator base by a spring wire, and a coil for performing tilt correction is provided on the lens holder, and a magnet is provided on the actuator base side to face the coil. By controlling the flowing current, the lens holder can be tilted in the radial direction. In these technologies, since the tilt of the objective lens is corrected by mechanically tilting only the lens holder, the driving weight can be reduced as compared with the above-described conventional optical head tilting mechanism.
Since the driving mechanism is simple and has a high frequency response characteristic, it is possible to quickly follow a change in the inclination of the recording surface caused by the rotation of the optical disk.

[0007]

However, in such a technique in which only the lens holder is capable of correcting the tilt, the lens holder is supported on the base member by one kind of elastic support member, so that the optical disk is actually used. When applied to the apparatus, the dynamic characteristics in each of the movement in the focus direction, the movement in the track direction, and the movement in the radial tilt direction in the lens holder cannot be set individually, making it difficult to control the objective lens actuator in each direction. There is a problem. In particular, the movement in the track direction and the movement in the radial tilt direction and the focus direction require moving the lens holder in directions orthogonal to each other. In order to satisfy this, in the former example, the lens holder is supported on the base side by a spring wire, so that driving in each direction is mutually affected, for example, when driving in the radial tilt direction, it affects the track direction. This makes it difficult to control the drive independently without the need for a drive.

In the above-described conventional technique, it is conceivable that the movement of the lens holder in the track direction is controlled by a servo mechanism based on the output of a photodetector such as a photodiode provided in an optical system. However, in this case, the output of the photodetector includes a component due to the movement of the lens holder in the track direction and the inclination in the radial direction,
With the servo mechanism, it is difficult to accurately control the position of the lens holder in the track direction. For this reason, conventionally, it is necessary to perform the movement control in the track direction from the output detected by the photodetector while compensating for the detection amount due to the inclination in the radial direction, which makes the movement control in the track direction difficult. .

The present invention solves the problems of the prior art and provides an objective lens actuator capable of easily performing drive control in a focus direction, a track direction, and a radial tilt direction with high responsiveness. The purpose is to do.

[0010]

In order to achieve the above object, an objective lens actuator according to the present invention comprises a fixed track holder fixed to a base, and a first track projecting from the fixed track holder and capable of deforming in the track direction. A movable track holder supported by the first elastic support member, a lens holder protruded from the movable track holder and supported by a second elastic support member deformable in a focus direction orthogonal to the track direction; An objective lens held by a lens holder and facing the optical disk, a plurality of coil elements provided in the lens holder, and a plurality of magnets fixed to the base are provided, and a predetermined current is supplied to the coil element. Flowing, controlling the drive of the lens holder in the track direction by deforming the first elastic support member,
The second elastic support member is deformed to drive and control the lens holder in a focus direction and a radial tilt direction. For example, the first elastic support member includes a plurality of hinge springs that can be deformed in a track direction,
The second elastic support member includes a plurality of leaf springs that are deformable in the focus direction and are arranged in parallel with each other.

In the objective lens actuator according to the present invention, a track position detecting sensor for detecting a position of the movable track holder in a track direction, and a predetermined current is supplied to the coil element based on an output of the track position detecting sensor. A control circuit for controlling the position of the objective lens in the track direction, and performing accurate position control of the objective lens in the track direction. Further, in the present invention, a tilt sensor for detecting a tilt of the lens holder in a radial direction, and a predetermined current is supplied to the coil element based on an output of the tilt sensor to control a tilt of the objective lens in a radial direction. A control circuit for accurately controlling the tilt of the objective lens in the radial direction.

According to the present invention, the drive of the lens holder is controlled in the track direction by the deformation of the first elastic support member, and the drive of the lens holder is controlled in the focus direction and the radial tilt direction by the deformation of the second elastic support member. Therefore, the drive control can be performed independently of the track direction and the radial tilt direction independently of each other, and the drive control can be facilitated. This makes it possible for the objective lens to follow the rotating optical disk at high speed in the focus direction, the track direction, and the radial tilt direction.

According to the present invention, the position of the movable track holder is detected by the position detection sensor,
The accurate position of the objective lens in the track direction can be detected, and the tilt of the lens holder in the radial direction can be detected by the tilt sensor, whereby the tilt of the objective lens in the radial tilt direction can be detected. This makes it possible to control the inclination of the objective lens in the track direction and the radial direction with high accuracy.

[0014]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external view of an objective lens actuator of the present invention, and FIG. 2 is a plan view thereof. In each figure, TR indicates a track direction, TN indicates a tangential direction, and FC indicates a focus direction. In these drawings, a base 10 of an objective lens actuator movably arranged along a recording surface of an optical disc 100 has an objective lens 1 having an optical axis directed in a focus direction FC perpendicular to the surface of the base 10. Is held in the focus direction FC
And is supported so as to be able to move minutely in a direction parallel to the surface of the base 10. That is, a wall-shaped fixed track holder 12 is erected and fixed on a part of the base 10, and can be deformed from the fixed track holder 12 in a direction parallel to a base surface as a first elastic support member. A plurality of hinge springs 14 protrude in the tangential direction with one end supporting structure, and the other end of the hinge springs 14 supports a movable track holder 13 having a laterally H-shaped lateral view. Thus, the movable track holder 13 is held on the surface of the base 10 so as to be able to move minutely in a direction parallel to the surface of the base 10. Also,
From the four H-shaped ends of the movable track holder 13, the focus direction F
The four leaf springs 15 that can be deformed into C
In the tangential direction TN, which is opposite to the above, a one-side support structure protrudes in parallel with the tangential direction TN, and the other end of the leaf spring 15 supports the lens holder 11. Thus, the lens holder 11 is held on the surface of the base 10 so as to be finely movable in the focus direction. In addition,
FIG. 3 shows the base 10, the lens holder 12, the fixed track holder 12, the movable track holder 13, and the hinge spring 1.
FIG. 4 is a schematic side view showing a mutual configuration of a leaf spring and a leaf spring.

The lens holder 11 has cut grooves 11a in the focus direction formed at both ends in the tangential direction TN, and the lens holder 1 extends along the peripheral surface thereof.
1 is provided with a focusing coil 16. Track coils 17a and 17b are respectively provided on both end surfaces of the lens holder 11 in the tangential direction. Main base yokes 18a and 18b are fixed to the base 10, one of which is disposed in the cut groove 11a and the other of which has an upward U-shape facing the end face in the tangent shell direction TN. A pair of opposite-pole magnets 19a and 19b are arranged on the other end of the main yokes 18a and 18b so as to face the focusing coil 16 and the track coils 17a and 17b. Is configured.

A radial tilt coil 20 is provided on each end face of the lens holder 11 in the radial direction.
a, 20b. The base 10 has side yokes 21a, 2 which are opposed to both end surfaces in the tangential direction of the radial tilt coils 20a, 20b and have an upward E-shape in parallel with the both end surfaces.
1b is fixed. And the side yoke 21
a, 21b are the radial tilt coils 2
0a, 20b and two pairs of opposite-pole magnets 22a, 22b, 22c, 22d are provided on both side pieces located inside the radial tilt coils 20a, 20b.
Are arranged so as to face each other to form a closed magnetic circuit.

A track position detecting sensor plate 24 projects from the movable track holder 13 in the tangential direction opposite to the lens holder 11. A track position detection sensor 25 is provided facing the detection sensor plate 24. In the track position detection sensor 25, as shown in FIG. 4A, a light emitting diode LED is disposed at the center, and phototransistors (or photodiodes) PT1 and PT2 are disposed on both sides thereof, and the light emitting diode LED emits light. Then, the light is reflected by the track position detection sensor plate 24, and the reflected light is received by the left and right phototransistors PT1 and TT2. When the lens holder 11 is located at the center position in the track direction, the left and right phototransistors PT1 and PT2 are set to have the same amount of received light.

The base 10 is provided with a tilt sensor 23 in a direction facing the surface of the radial tilt coil 20b which is not in contact with the lens holder 11 in the radial direction. The tilt sensor 23 is shown in FIG.
As shown in (b), the track position detection sensor 25
The light emitting diode L has a light emitting diode L disposed at the center and a pair of phototransistors PT1 and PT2 sandwiching the light emitting diode LED vertically.
The ED emits light and is reflected by the opposite surface of the radial tilt coil 20b.
1 and PT2. When the lens holder 11 is located at the center position in the radial tilt direction, the light reflected by the radial tilt coil 20b is set to have the same amount of light received by the phototransistors PT1 and PT2 on both sides.

Here, as shown in FIG. 5, the focus coil 16, track coils 17a and 17b, radial tilt coil 20
a and 20b are configured such that a current supplied thereto is controlled by a control circuit 30 such as a CPU.
0, the track position detection sensor 25 and the tilt sensor 23 are connected to each other.
5, the current of the track coils 17a, 17b is controlled, and the output of the tilt sensor 23 controls the current of the radial tilt coils 20a, 20b. The current of the focusing coil 16 is controlled by a servo mechanism including a photo sensor (not shown) constituting an optical system together with the objective lens 1 as in the conventional optical disk apparatus.

The operation of the objective lens actuator having the above configuration will be described. Referring to FIG. 2, the control circuit 30, which is also configured as a part of a focus servo mechanism (not shown), supplies a current to the focusing coil 16 so that the main yokes 18a and 18b and a pair of magnets provided thereon are provided. By setting the direction of the magnetic field of the closed magnetic circuit constituted by 19a and 19b as a counter electrode, a driving force is generated in the focus direction FC according to Fleming's left-hand rule. This driving force causes the lens holder 11 to move the leaf spring 15
Is moved in the focus direction FC while deforming, and the objective lens 1 fixed to the lens holder 11 is driven in the focus direction FC to perform focus control.

The control circuit 30 causes currents in opposite directions to flow through the track coils 17a and 17b, thereby closing the closed magnetic circuit constituted by the main yokes 18a and 18b and the magnets 19a and 19b provided thereon. A driving force in the track direction TR is generated in the lens holder 11 by Fleming's left-hand rule. Here, since the leaf spring 15 does not deform in the track direction, the lens holder 11 is driven in the track direction integrally with the leaf spring 15 and the movable track holder 11 while deforming the hinge spring 14 by the driving force in the track direction. You.
Thus, the objective lens 1 fixed to the lens holder 11 is driven in the track direction. At this time, FIG.
Referring to (a), the track position detection sensor plate 24 fixed to the movable track holder 13 moves in the track direction together with the movable track holder 13 and is arranged in a direction facing the track position detection sensor plate 24. In the track position detection sensor 25, since there is a difference between the received light amounts of the pair of phototransistors PT1 and PT2, the movement amount of the lens holder 11 in the track direction is detected based on the output difference. Therefore, the control circuit 30 sends the track coil 17 so that the output difference becomes zero.
a, 17b to control the current flowing through the objective lens 1
Can always be controlled to the track center position.

Further, the control circuit 30 allows a current in the opposite direction to flow through the radial tilt coils 20a, 20b, so that the side yoke 21a and the magnets 22a, 22b
And a side yoke 21b and a magnet 22c,
22d, the side yokes 21a and 21b are formed according to Fleming's left-hand rule.
b, a driving force is generated in the opposite direction along the focus direction FC. This driving force causes the lens holder 1
1 is driven while deforming the leaf springs 15 and deforming both ends in opposite directions along the focus direction. As a result, the lens holder 11 is tilted and driven in the radial direction, so that the objective lens 1 fixed to the lens holder 11 is driven in the radial tilt direction. At this time, referring to FIG. 4B, the tilt sensor 23 arranged in a direction facing the side surface in the radial direction of the radial tilt coil 20b causes a difference in the amount of received light between the pair of phototransistors PT1 and PT2. Therefore, the radial tilt amount of the lens holder 11 is detected based on the output difference. Therefore, by controlling the current flowing from the control circuit 30 to the radial tilt coils 20a and 20b so that the output difference becomes zero, the objective lens 1 can be controlled to a radial tilt inclination corresponding to the inclination of the optical disk. Become.

As described above, in the objective lens actuator of this embodiment, the lens holder 11 holding the objective lens 1 is supported on the base 10 and is movable with respect to the fixed track holder 12 provided on the base 10. The track holder 13 is held by a hinge spring 14 so as to be movable in the track direction.
In contrast, the lens holder 11 is held by the leaf spring 15 so as to be movable in the focus direction and the radial tilt direction, so that mutual influence between the track direction and the radial tilt direction is prevented, and each direction is prevented. Drive control can be performed independently. Further, by providing the track-direction position sensor 25 and the radial-direction tilt sensor 23, when the drive for correcting the position of the objective lens 1 with respect to the inclination of the recording surface of the optical disc 100 is performed,
The position of the objective lens 1 in the track direction and the tilt in the radial direction can be accurately detected, so that the position control of the objective lens 1 can be facilitated and the accuracy can be increased.

Here, the track position detection sensor and the tilt sensor in the present invention are not limited to the configuration of the above-described embodiment. In the above embodiment, the output of each sensor is input to the control circuit, and the control circuit controls the track position and the tilt in the radial direction. However, the track position and the radial position are controlled based on the output of each sensor. The configuration may be such that the inclinations of the directions are controlled by independent control systems. Further, it goes without saying that the configuration of the coil and the magnet for driving in each direction is not limited to the configuration of the above embodiment.

[0025]

As described above, according to the present invention, the lens holder is driven and controlled in the track direction by the deformation of the first elastic support member, and the lens holder is moved in the focus direction and the radial tilt by the deformation of the second elastic support member. Drive control in the direction, so that the conventional focus direction,
There is an effect that independent setting of the characteristics in the track direction becomes possible, which is not possible with a structure in which a single support portion is used for driving in the track direction and in the radial tilt direction. Also, the present invention includes a sensor for detecting the amount of movement of the lens holder in the track direction and a sensor for detecting the tilt in the radial direction, so that the position of the objective lens is corrected for the tilt of the recording surface of the optical disc. When the driving is performed, the position of the objective lens in the track direction and the inclination in the radial direction can be controlled with high accuracy, and this has an effect that the position control of the objective lens can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an embodiment of an objective lens actuator according to the present invention.

FIG. 2 is a diagram of the objective lens actuator of FIG. 1 as viewed from a direction normal to a recording surface of an optical disc.

FIG. 3 is a schematic perspective view for explaining an elastic support structure of the objective lens actuator of FIG. 1;

FIG. 4 is a diagram schematically showing a configuration of a track position detection sensor and a tilt sensor.

FIG. 5 is a schematic block diagram showing the configuration of each coil, sensor, and control circuit.

[Explanation of symbols]

 Reference Signs List 1 Objective lens 10 Base 11 Lens holder 12 Movable track holder 13 Fixed track holder 14 Hinge spring 15 Leaf spring 16 Focusing coil 17a, 17b Track coil 18a, 18b Main yoke 19a, 19b Magnet 20a, 20b Radial tilt coil 21a, 21b Side yokes 22a to 22d Magnet 23 Tilt sensor 24 Track position detection sensor plate 25 Track position detection sensor 30 Control circuit 100 Optical disk

Claims (5)

[Claims] 1. A fixed track holder fixed to a base, a movable track holder projecting from the fixed track holder and supported by a first elastic support member deformable in a track direction, and a movable track holder. A lens holder protruded and supported by a second elastic support member deformable in a focus direction perpendicular to the track direction; an objective lens held by the lens holder and facing the optical disc; and the lens holder. A plurality of coil elements provided, and a plurality of magnets fixed to the base, applying a predetermined current to the coil elements, deforming the first elastic support member, and driving the lens holder in the track direction. And driving the lens holder in the focus direction and the radial tilt direction by deforming the second elastic support member. An objective lens actuator for an optical disk device, characterized in that: 2. The first elastic support member includes a plurality of hinge springs that can be deformed in a track direction.
2. The objective lens actuator according to claim 1, wherein the elastic support member comprises a plurality of leaf springs which are deformable in a focus direction and are arranged in parallel with each other. 3. A track position detection sensor for detecting a position of the movable track holder in a track direction, and a predetermined current is applied to the coil element based on an output of the track position detection sensor, and a predetermined current is applied to the track direction of the objective lens. 3. The objective lens actuator for an optical disk device according to claim 1, further comprising a control circuit for controlling a position, wherein the control circuit performs accurate position control of the objective lens in a track direction. 4. A tilt sensor for detecting a tilt of the lens holder in a radial direction, and a control for flowing a predetermined current to the coil element based on an output of the tilt sensor to control a tilt of the objective lens in a radial direction. 4. An objective lens actuator for an optical disk device according to claim 1, further comprising a circuit, for performing accurate tilt control of the tilt of the objective lens in a radial direction. 5. The track position detection sensor and the tilt sensor each include a light-emitting element and a pair of light-receiving elements disposed with the light-emitting element interposed therebetween, and the movable track holder or the lens holder has a predetermined center position or 5. The objective lens actuator according to claim 3, wherein an output difference between the pair of light receiving elements is set to a predetermined value when the pair is at a predetermined tilt position.