JPH10326427A - Objective lens driving device, and optical pickup device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high frequency band of a servo frequency by making a movable part supporting an objective lens of an objective lens driving device high rigidity. SOLUTION: This driving device is provided with a movable part 2 supporting an objective lens 7, and a fixing part 3 supporting the movable part 2 through one pair of elastic member 4 being parallel, further in which the movable part 2 supporting the objective lens 7 is made high rigidity. For this reason, a plate type reinforcement plate 2a of which rigidity is larger than that of synthetic resin as aluminum alloy, magnesium alloy, and the like is fixed to a plane of either of the upper plane or the lower plane in the direction of an optical axis of the objective lens 7 of the movable part 2 supporting the objective lens 7 and constituted with synthetic resin and the like.

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 and an optical pickup device using the same, and more particularly, to an objective lens driving device for increasing the band of focusing and tracking servo frequencies and an optical pickup using the same. Related to the device.

[0002]

2. Description of the Related Art In recent years, information processing apparatuses such as computers have remarkably developed a processing capability for processing a large amount of information at a high speed. Accordingly, an information recording and reproducing apparatus has a function of recording and reproducing a large amount of information at a high speed. Is required. An optical recording medium provided for an optical recording / reproducing apparatus which is an example of the information recording / reproducing apparatus includes a ROM (Read O / O).
nly Memory) disks and RAM (Rando)
There are disc-shaped discs such as a m Access Memory disc, and these discs tend to have higher and higher rotation speeds in order to record or reproduce the above-mentioned high-speed and large-volume information. Therefore, an objective lens driving device such as a one-axis actuator that controls and drives the objective lens in only one of the focusing direction and the tracking direction, and a two-axis actuator that controls and drives the objective lens in both the focusing direction and the tracking direction. Are required to have no harmful double resonance up to a high frequency. For example, in a 16 × CD-ROM drive, the servo band for focusing is almost 4 kHz,
In general, in order to stabilize the servo, 5 kHz of 4 kHz
There is a demand for no harmful double resonance up to ten times the frequency. Further, along with a demand for a smaller and thinner optical recording / reproducing device, a smaller and thinner optical pickup device is required, and a smaller and thinner objective lens driving device, which is the above-described servo actuator, is inevitably required.

However, the harmful double resonance is caused by the rigidity of the movable part to which the objective lens is attached and which constitutes the objective lens driving device. At present, it is very difficult to increase the frequency of harmful double resonance. Accordingly, there is a need for an objective lens driving device and an optical pickup device using the same, which achieve high rigidity without impairing the size and thickness of the movable portion to which the objective lens is fixed, and which can cope with a high rotational speed of the optical recording medium. I have.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to increase the rigidity of a movable portion of an objective lens driving device to which an objective lens is fixed, thereby realizing a higher servo frequency band and an objective lens driving device. An object of the present invention is to provide an optical pickup device used.

[0005]

In order to solve the above-mentioned problems, in the objective lens driving device according to the first aspect of the present invention, at least a movable portion to which the objective lens is fixed, and a pair of parallel elastic members are used as the movable portion. In an objective lens driving device having a fixed portion that supports the objective lens, in order to increase the rigidity of the movable portion to which the objective lens is fixed, the objective lens is fixed, and at least the objective lens of the movable portion made of synthetic resin or the like A plate-like reinforcing plate having rigidity greater than that of a synthetic resin, such as an aluminum alloy or a magnesium alloy, is fixed to one of the upper surface and the lower surface in the optical axis direction.

In the objective lens driving device according to the second aspect of the present invention, the center hole, the objective lens fixed to a position eccentric from the center hole, and condensing the light beam on the optical recording medium, and the outer periphery concentric with the center hole. A movable part fixed to the side surface and having a focusing coil driven in the focusing direction of the optical recording medium, a tracking coil driven in the tracking direction of the optical recording medium, and opposed to the focusing coil and the tracking coil A so-called rotary type driving device having a yoke base that forms a magnetic circuit with a yoke, a magnet fixed to the yoke, and a central axis vertically extending from the yoke base in the focusing direction and passing through a center hole. In the axis actuator, the objective lens is fixed to increase the rigidity of the movable part to which the objective lens is fixed. At least one of the upper surface and the lower surface of the movable portion made of synthetic resin or the like in the optical axis direction of the objective lens has a plate-like shape having a greater rigidity than a synthetic resin such as an aluminum alloy or a magnesium alloy. Characterized in that the reinforcing plate is fixed.

In an optical pickup device according to a third aspect of the present invention, an objective lens driving device having at least a movable portion to which an objective lens is fixed, and a fixed portion that supports the movable portion via a pair of parallel elastic members; In order to increase the rigidity of a movable portion to which an objective lens is fixed in an optical pickup device having a semiconductor laser as a light source and a light receiving element for photoelectrically converting laser light emitted from the semiconductor laser and reflected by an optical recording medium. In addition, an objective lens is fixed, and at least one of the upper surface and the lower surface in the optical axis direction of the objective lens of the movable portion made of a synthetic resin or the like, is made of a synthetic resin such as an aluminum alloy or a magnesium alloy. A plate-like reinforcing plate having high rigidity is fixed.

According to a fourth aspect of the present invention, there is provided an optical pickup device comprising: a center hole; an objective lens fixed at a position eccentric from the center hole; and an outer peripheral surface concentric with the center hole.
A focusing coil driven in the focusing direction of the optical recording medium, a movable portion having a tracking coil driven in the tracking direction of the optical recording medium, a yoke arranged opposite to the focusing coil and the tracking coil, and a yoke. An objective lens driving device having a yoke base that forms a magnetic circuit with the fixed magnet, a central axis that is suspended from the yoke base in the focusing direction, and that passes through a central hole of a movable portion that holds the objective lens, and a light source In order to increase the rigidity of the movable part to which the objective lens is fixed, in an optical pickup device having a semiconductor laser which is a semiconductor laser and a light receiving element which photoelectrically converts the laser light emitted from the semiconductor laser and reflected by the optical recording medium, , The objective lens is fixed, and at least a pair of movable parts made of a synthetic resin or the like. On either side of the upper and lower surfaces of the optical axis of the lens, wherein the rigid than the synthetic resin as such as an aluminum alloy or a magnesium alloy is stuck a plate-like reinforcing plate is larger.

According to the above-described means, it is possible to increase the rigidity of the movable portion to which the objective lens is fixed, so that it is possible to provide an objective lens driving device in which the multiple resonance frequency of the movable portion is shifted to a higher frequency. In an optical pickup device using this objective lens driving device, it is possible to increase the focusing and tracking servo bands.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Harmful double resonance is caused by the rigidity of a movable portion to which an objective lens is attached and which constitutes an objective lens driving device. The present invention aims at increasing the rigidity of the movable portion. is there. Hereinafter, an example of a specific embodiment to which the present invention is applied will be described with reference to FIGS.

Embodiment 1 In this embodiment, as an example, an objective lens driving device that drives an objective lens only in a focusing direction is a schematic plan view of an objective lens driving device 1 and is schematically shown in FIGS. This will be described with reference to FIG. 2 which is an AA sectional view, and FIG. 3 which is a schematic external perspective view of the objective lens driving device 1. In addition, an optical pickup device using the objective lens driving device 1 will be described with reference to FIG. 4 which is a schematic configuration diagram.

As shown in FIGS. 1-3, the objective lens 7
Is fixed by an adhesive or the like to the movable portion 2 integrally formed of a synthetic resin or the like, and a focusing coil 2b is wound around a side surface of the movable portion 2. A reinforcing plate 2a made of a component material of the movable portion 2, for example, an aluminum alloy or a magnesium alloy having rigidity greater than that of a synthetic resin is fixed to an under surface of the movable portion 2 in the focusing direction with an adhesive or the like. . As a result, the rigidity of the movable section 2 can be increased. The movable part 2 is supported by an elastic member 4 composed of a pair of parallel springs extending from the fixed part 3, and the fixed part 3 is fixed to a yoke base 5 composed of a magnetic material such as iron. . The yoke base 5 is formed with a pair of yokes 5a, a part of which is bent in the focusing direction, and a magnet 6 is fixed to an opposing surface of each yoke 5a with an adhesive or the like. And
A current based on a focusing error signal detected by a light-receiving element described later flows through the focusing coil 2b of the movable section 2 holding the objective lens 7, and is driven in the focusing direction based on the magnitude and direction of the current.

FIG. 4 shows an example of an optical pickup device using the above-described objective lens driving device 1, which is referred to as a separated type in which a movable portion is reduced in weight in order to cope with high-speed access. . That is, a fixed optical system 17 composed of a semiconductor laser 9, which is a light source, a light receiving element 10 for detecting a focusing error signal, a tracking error signal, an RF signal, and the like, and a galvanomirror 12 that rotates based on the tracking error signal, etc. The movable optical system 8 which is fixed to a chassis or the like of the recording / reproducing apparatus and includes the objective lens driving device 1 and the like is movable in the tracking direction by driving means (not shown) such as a linear motor.

The laser light emitted from the semiconductor laser 9 is converted into parallel laser light by the collimator lens 13, reflected on the total reflection surface and the polarizing film forming surface of the beam splitter 14, and guided to the galvanometer mirror 12. The laser beam reflected by the galvanomirror 12 is reflected by the mirror 15 of the movable optical system 8 toward the optical recording medium 11, and is reflected on the optical recording medium 11 by the objective lens 7 held by the movable section 2 of the objective lens driving device 1. It is collected. The laser beam reflected by the optical recording medium 11 passes through the objective lens 7 and passes through the mirror 1
5. The light is reflected by the galvanometer mirror 12, passes through the beam splitter 14, and the condenser lens 16, and is focused on the light receiving element 10, and a focusing error signal, a tracking error signal, an RF signal, and the like are detected.

In the present embodiment, as a means for increasing the rigidity of the movable portion 2 of the objective lens driving device 1, an example is shown in which a reinforcing plate 2a is fixed to the lower surface of the movable portion 2 in the focusing direction. The plate 2a may be fixed to the upper surface of the movable portion 2 in the focusing direction. If the reinforcing plate 2a is fixed to the upper and lower surfaces of the movable portion 2 in the focusing direction, the rigidity of the movable portion 2 can be further increased. Further, in the present embodiment, the objective lens driving device 1 in which the objective lens 7 is driven only in the focusing direction is shown, but the objective lens 7 can be moved in any of the focusing direction and the tracking direction. It can be applied to a so-called two-axis actuator. That is, the reinforcing plate 2a is fixed to the lower surface in the focusing direction of the movable portion 2 holding the objective lens 7 in the biaxial actuator, the reinforcing plate 2a is fixed to the upper surface of the movable portion 2 in the focusing direction, or the reinforcing plate 2a is movable. By fixing the movable portion 2 to both the upper and lower surfaces in the focusing direction, the rigidity of the movable portion 2 can be increased.

In this manner, the rigidity of the movable section 2 to which the objective lens 7 is fixed can be increased. Therefore, it is possible to provide the objective lens driving device 1 in which the multiple resonance frequency is shifted to a higher frequency range, and the optical pickup device using the objective lens driving device 1 can achieve a higher focusing and tracking servo band.

Embodiment 2 In this embodiment, as an example, an objective lens driving device which holds two objective lenses in a movable portion and is compatible with optical recording media of different types such as substrate thickness and recording density. Will be described with reference to FIG. 5 which is a schematic external perspective view and FIG. 6 which is a schematic exploded view. An optical pickup device using the objective lens driving device 1 will be described with reference to FIG. 7 which is a schematic configuration diagram.

As shown in FIGS. 5 and 6, a central portion of a movable portion 2 integrally formed of a synthetic resin or the like is provided with a central hole inserted from a yoke base 5 into a central shaft 5b suspended in a focusing direction. 2d is provided. An eccentric position substantially symmetrical with respect to the center of the center hole 2d on the upper surface of the movable portion 2 in the focusing direction has an NA (Numerica
l Aperture) etc. of the first objective lens 7
a and the second objective lens 7b are fixed. Further, a pair of focusing coils 2b and a pair of tracking coils 2c, which are arranged symmetrically with respect to the center hole 2d, are fixed to side surfaces substantially concentric with the center hole 2d of the movable portion 2. On the lower surface of the movable part 2 in the focusing direction, a reinforcing plate 2a made of a component material of the movable part 2, for example, an aluminum alloy or a magnesium alloy having higher rigidity than a synthetic resin or the like is fixed by an adhesive or the like. Have been. As a result, the rigidity of the movable section 2 can be increased. Focusing coil 2b and tracking coil 2c of yoke base 5 made of magnetic material such as iron
The yokes 5a bent in the focusing direction are formed at positions corresponding to the above. The magnets 6 are fixed to the opposing surfaces of the yokes 5a with an adhesive or the like.
In this case, the direction of the magnetic field formed by the magnet 6 fixed to the yoke 5a corresponding to the focusing coil 2b is the focusing direction, and the magnet 6 fixed to the yoke 5a corresponding to the tracking coil 2c.
Is a direction perpendicular to the focusing direction. In the movable section 2 holding the objective lens 7, a current based on a focusing error signal and a tracking error signal detected by a light receiving element, which will be described later, is passed through the focusing coil 2b and the tracking coil 2c. The movable section 2 is guided and driven in the focusing direction and the tracking direction (the movable section 2 rotates about the central axis 5b) based on the direction of the movable section 2.

FIG. 7 shows an example of an optical pickup device using the objective lens driving device 1 described above. Laser light emitted from the semiconductor laser 9 and reflected by the beam splitter 14 is converted into parallel laser light by the collimator lens 13, and is converted by the first objective lens 7 a held by the movable section 2 of the objective lens driving device 1. One optical recording medium 11
The light is focused on a. The first optical recording medium 11a corresponding to this optical system is, for example, a DVD (Digital Video Disk or Digital Versatile Disk) on which a substrate having a thickness of 0.6 mm is bonded, and the semiconductor laser 9 in this case has a wavelength of 635. ~ 65
The first objective lens 7a having a wavelength of 0 nm and an NA of 0.6 is generally used. The laser beam reflected by the first optical recording medium 11a passes through the first objective lens 7a, the collimator lens 13, and the beam splitter 14, and passes through the light receiving element 10
The focusing error signal, the tracking error signal, the RF signal, and the like are detected by the light receiving element 10.

Reference numeral 20 denotes a so-called laser coupler in which a light receiving element and a semiconductor laser are integrally formed on a semiconductor substrate. The laser light emitted from the semiconductor laser of the laser coupler 20 is transmitted to the second optical recording medium 11 by the second objective lens 7b held by the movable section 2 of the objective lens driving device 1.
b. A second optical recording medium 11b corresponding to this optical system has a C
D (Compact Disk) or the like. In this case, a semiconductor laser having a wavelength of about 780 nm and a second objective lens 7b having an NA of 0.45 are generally used. The laser light reflected by the second optical recording medium 11b passes through the second objective lens 7b and is condensed on the light receiving element of the laser coupler 20, where the focusing error signal, the tracking error signal, the RF signal, etc. Is detected.

The movable section 2 holds two objective lenses, a first objective lens 7a and a second objective lens 7b, and drives the objective lenses corresponding to different types of optical recording media such as substrate thickness and recording density. The optical system such as the device 1, the semiconductor laser 9, the beam splitter 14, the collimator lens 13, the light receiving element 10, and the laser coupler 20 are integrally formed with an optical block 18. The optical block 18 is substantially parallel to the main guide shaft 19a and the main guide shaft 19a for regulating the optical block 18 in both directions perpendicular to the focusing direction and the tracking direction.
Sub-guide shaft 19b for regulating 8 in the focusing direction
, And can be integrally moved in the tracking direction. Although not shown, it is driven in the tracking direction by a driving means constituted by a linear motor or the like.

In the present embodiment, as a means for increasing the rigidity of the movable portion 2 of the objective lens driving device 1, an example is shown in which a reinforcing plate 2a is fixed to the lower surface of the movable portion 2 in the focusing direction. The plate 2a may be fixed to the upper surface of the movable portion 2 in the focusing direction. If the reinforcing plate 2a is fixed to the upper and lower surfaces of the movable portion 2 in the focusing direction, the rigidity of the movable portion 2 can be further increased. Further, in the present embodiment, the objective lens driving device 1 in which two objective lenses are held by the movable unit 2 like the first objective lens 7a and the second objective lens 7b having different NAs is shown. However, the present invention can also be applied to a case where one objective lens is held by the movable section 2.

In this way, for example, the rigidity of the movable section 2 holding the first objective lens 7a and the second objective lens 7b can be increased. Therefore, it is possible to provide the objective lens driving device 1 in which the multiple resonance frequency is shifted to a higher frequency range, and the optical pickup device using the objective lens driving device 1 can achieve a higher focusing and tracking servo band.

[0024]

According to the objective lens driving device of the present invention,
The rigidity of the movable section holding the objective lens can be increased. The optical pickup device using this objective lens driving device can increase the servo frequency band.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an objective lens driving device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view taken along the line AA in FIG.

FIG. 3 shows the first embodiment of the present invention, and is a schematic external perspective view of an objective lens driving device.

FIG. 4 is a schematic diagram illustrating an optical pickup device according to a first embodiment of the present invention.

FIG. 5 is a schematic external perspective view of an objective lens driving device according to a second embodiment of the present invention.

FIG. 6 is a schematic exploded view of an objective lens driving device according to a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an optical pickup device according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Objective lens drive device, 2 ... Movable part, 2a ... Reinforcement plate,
2b: Focusing coil, 2c: Tracking coil, 2d: Center hole, 3: Fixed part, 4: Elastic member, 5
... Yoke base, 5a ... Yoke, 5b ... Center axis, 6 ... Magnet, 7 ... Objective lens, 7a ... First objective lens,
7b: second objective lens, 8: movable optical system, 9: semiconductor laser, 10: light receiving element, 11: optical recording medium, 11a ...
A first optical recording medium, 11b... A second optical recording medium, 12.
Galvano mirror, 13: Collimator lens, 14: Beam splitter, 15: Mirror, 16: Condensing lens, 17
... fixed optical system, 18 ... optical block, 19a ... main guide shaft, 19b ... sub guide shaft, 20 ... laser coupler

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI G11B 19/02 501 G11B 19/02 501B

Claims (4)

[Claims] 1. An objective lens driving device having at least a movable portion for fixing an objective lens and a fixed portion for supporting the movable portion via a pair of parallel elastic members, wherein at least the objective lens of the movable portion is provided. An objective lens driving device, wherein a plate-shaped reinforcing plate is fixed to one of the upper surface and the lower surface in the optical axis direction of the movable member, and the reinforcing plate has a greater rigidity than a constituent material of the movable portion. . 2. A center hole, an objective lens fixed to an eccentric position of the center hole, and an objective lens for condensing a light beam on an optical recording medium; and an optical recording medium fixed to an outer peripheral side surface concentric with the center hole. A movable part having a focusing coil driven in the focusing direction of the optical recording medium, a tracking coil driven in the tracking direction of the optical recording medium, a yoke arranged to face the focusing coil and the tracking coil, and the yoke A yoke base that forms a magnetic circuit with a magnet fixed to the yoke base, and is suspended from the yoke base in a focusing direction;
An objective lens driving device having a central axis inserted through the central hole, wherein a plate-like reinforcing plate is fixed to at least one of an upper surface and a lower surface of the movable portion in the optical axis direction of the objective lens, The objective lens driving device, wherein the reinforcing plate has a greater rigidity than a constituent material of the movable portion. 3. An objective lens driving device having at least a movable portion to which an objective lens is fixed, a fixed portion supporting the movable portion via a pair of parallel elastic members, a semiconductor laser as a light source, and the semiconductor An optical pickup device having a light-receiving element that photoelectrically converts laser light emitted from a laser and reflected by an optical recording medium, wherein at least one of an upper surface and a lower surface of the movable portion in the optical axis direction of the objective lens. An optical pickup device, wherein a plate-like reinforcing plate is fixed to a surface, and the reinforcing plate has higher rigidity than a constituent material of the movable portion. 4. A center hole, an objective lens fixed to an eccentric position of the center hole, and an objective lens for condensing a light beam on an optical recording medium, and an optical recording medium fixed to an outer peripheral side surface concentric with the center hole. A movable part having a focusing coil driven in the focusing direction of the optical recording medium, a tracking coil driven in the tracking direction of the optical recording medium, a yoke arranged to face the focusing coil and the tracking coil, and the yoke A yoke base that forms a magnetic circuit with a magnet fixed to the yoke base, and is suspended from the yoke base in a focusing direction;
An objective lens driving device having a center axis inserted through the center hole; a semiconductor laser as a light source; and a light receiving element for photoelectrically converting a laser beam emitted from the semiconductor laser and reflected by the optical recording medium. In the optical pickup device, a plate-like reinforcing plate is fixedly attached to at least one of an upper surface and a lower surface of the movable portion in the optical axis direction of the objective lens, and the reinforcing plate is larger than a constituent material of the movable portion. An optical pickup device having high rigidity.