JPH10340464A - Objective lens driving device and optical head device - Google Patents

Abstract

(57) Abstract: The present invention has a structure capable of contributing to reduction in size and weight of an optical head device itself, and efficiently drives an objective lens in a focus direction and a tracking direction with power saving, respectively. It is an object of the present invention to provide a possible objective lens driving device and an optical head device having the same. A fixed permanent magnet (15a, 15b) is interposed in a magnetic field generated by the permanent magnets (15a, 15b). A blade 12 movably supported in the X direction along
The first and second drive coils 16a, 16b and 16b are respectively arranged side by side so as to face the permanent magnets 15a, 15b, and generate a driving force in the Z and X directions with respect to the blade 12 by flowing an electric current. 17a, 17b
And

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 driving an objective lens in a focusing direction and a tracking direction for recording and reproducing information on and from an optical disk, and an optical head device having the same. .

[0002]

2. Description of the Related Art As is well known, as an optical disk as mentioned above, a CD (Compound) on which audio data is recorded has been conventionally used.
Act Disks) and LDs (Laser Disks) in which both moving image data and audio data are recorded are widely used.

In recent years, not only moving image data and audio data but also sub-video data representing, for example, subtitles are compressed and recorded on an optical disk having the same diameter as a CD at a high density. Has also developed an optical disc, commonly known as a DVD, that allows the user to freely select and play back audio and subtitles in a desired language during playback by recording a plurality of types in different languages. Have been.

As a part of the development of this DVD, a DVD-ROM (Read Only Memory) and a D-ROM
Development for use as a VD-RAM (Read After Memory) is also being promoted.

On the other hand, as an optical disk apparatus for recording or reproducing data on or from such an optical disk, a rotary servo unit for controlling the rotation speed of the optical disk, a laser beam is irradiated on the signal recording surface of the optical disk, and the reflected light is photoelectrically converted. By doing so, an optical head device or the like for reading information recorded on the optical disk is provided. The original information is reproduced by subjecting the signal photoelectrically converted by this optical head device to waveform equalization processing, demodulation processing, and the like.

Here, the optical head device is provided with a focus drive mechanism and a tracking drive mechanism for performing focus servo and tracking servo on the objective lens. Among them, the focus drive mechanism has a function of finely driving the objective lens in the optical axis (focus) direction. Further, the tracking drive mechanism has a function of finely driving the objective lens in a direction (tracking direction) in which the track of the optical disk is traversed.

In the optical disk device, when the optical disk is mounted and driven to rotate, first, the focus drive mechanism is driven, and focus servo is performed on the objective lens. Thereafter, when the focus lens controls the objective lens near the in-focus position, the tracking drive mechanism is driven next to perform tracking servo on the objective lens.

FIG. 7 shows a conventional objective lens driving device for driving an objective lens in a focus direction and a tracking direction. That is, in FIG.
Is an objective lens held by the blade 2. Although the blade 2 will be described in detail later, the held objective lens 1 is moved in a focus direction indicated by an arrow Z in the figure and an arrow X in the figure.
It is supported by the mounting base 3 so that it can be moved in the tracking direction indicated by.

The mounting base 3 is fixed to a not-shown main chassis or the like of the optical head device, and is formed of a ferromagnetic material in a substantially plate shape. And this mounting base 1
The yokes 4a and 4b are formed on both sides of the tracking direction 3 in the same direction. Permanent magnets 5a, 5b are mounted inside the yokes 4a, 4b, and the blade 2 is arranged between the permanent magnets 5a, 5b so that the blade 2 is loosely inserted.

A pair of tracking driving coils 6a, 6a wound in a rectangular tube shape and an inner yoke 7a protruding from the mounting base 3 are formed on the side of the blade 2 facing the permanent magnet 5a. A positioned hollow focus drive coil 8a is provided. A pair of tracking drive coils 6b, 6b and a focus drive coil 8b positioned so as to surround the inner yoke 7b are also provided on the side of the blade 2 facing the permanent magnet 5b.

The tracking drive coil 6
By supplying a drive signal for tracking control to a and 6b, a driving force is generated on the blade 2 so that the objective lens 1 is moved in the tracking direction indicated by the arrow X in the figure. Further, the focus drive coils 8a,
By supplying a drive signal for focus control to 8b, a driving force is generated on the blade 2 so that the objective lens 1 is moved in the focus direction indicated by the arrow Z in the figure.

Here, a columnar supporting portion 9 is formed at an end of the mounting base 1 opposite to the end facing the objective lens 1 so as to stand substantially at a right angle. One end of a leaf spring 9a made of a metal material is embedded in the support portion 9. The other end of the leaf spring 9a is embedded in a holding member 2b bonded to the blade 2. Therefore, the blade 2 can move in the focus direction within a range where the leaf spring 9a can be shifted by its elastic force.

The holding member 2a is made of a synthetic resin material having elasticity, and has a hinge portion 2b narrowed in the width direction. For this reason, the blade 2 is rotatable in the horizontal direction by bending of the hinge portion 2b. Then, the rotating direction of the blade 2 corresponds to the tracking direction. The balancer 2c is attached to the blade 2 to smoothly rotate the blade 2 in the tracking direction.

[0014]

However, in the conventional objective lens driving apparatus as described above, as can be seen from FIG. 7, a pair of tracking driving coils 6a, 6a and 6a are provided outside the focus driving coils 8a and 8b, respectively.
b, 6b, that is, the focus driving coils 8a, 8b and the tracking driving coils 6a, 6
b are arranged so as to overlap in the tracking direction.

In other words, in the magnetic path formed by the permanent magnets 5a, 5b and the inner yokes 7a, 7b, the focus drive coils 8a, 8b and the tracking drive coils 6a, 6b
Are interposed in an overlapping manner.

For this reason, if the number of turns of the tracking drive coils 6a and 6b is increased in order to increase the tracking drive sensitivity, the shapes of the tracking drive coils 6a and 6b become larger, and accordingly, the focus drive coils 8a and 6b are correspondingly increased.
8b and the permanent magnets 5a and 5b become longer, which causes a problem that the focus drive sensitivity is reduced. Further, if the number of turns of the focus drive coils 8a and 8b is increased in order to increase the lowered focus drive sensitivity, the power consumption is increased, and the objective lens driving device itself is enlarged, and the optical head device is also enlarged. Occurs.

Therefore, the present invention has been made in view of the above circumstances, and has a structure that can contribute to the reduction in size and weight of the optical head device itself, and effectively applies a magnetic field of a magnet to a drive coil to achieve an objective. It is an object of the present invention to provide an extremely good objective lens driving device capable of efficiently driving a lens in a focusing direction and a tracking direction with power saving, respectively, and an optical head device including the same.

[0018]

An objective lens driving device according to the present invention comprises an objective lens for converging a laser beam emitted from a light source on an optical disc, and the objective lens in a radial direction and a normal direction of the optical disc. A magnetic circuit to drive;
It is intended to include an objective lens and a blade portion to which a magnetic circuit is fixed.

The magnetic circuit includes a magnet, a yoke provided to face the magnet, a first coil fixed to the blade portion and into which the yoke is loosely inserted, and a first coil fixed to the blade portion. And a second coil juxtaposed along the surface facing the magnet.

According to the above configuration, the second coils are juxtaposed along the surface of the first coil facing the magnet, so that the distance between the first and second coils and the magnet is reduced. The objective lens can be efficiently driven with power saving because the magnetic field of the magnet effectively acts on the first and second coils, respectively, while the size can be shortened and the size can be reduced. Will be able to

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. In FIG. 1, reference numeral 11 denotes an objective lens which is held by a blade 12. As will be described in detail later, the blade 12 is attached to the mounting base 13 so that the held objective lens 11 can be moved in a focus direction indicated by an arrow Z in the figure and a tracking direction indicated by an arrow X in the figure. Supported.

The mounting base 13 is fixed to a main chassis (not shown) of the optical head device, and is formed of a ferromagnetic material in a substantially plate shape. This mounting base 13 is
As shown in FIG. 2, both sides in the tracking direction are erected in the same direction to form yokes 14a and 14b. Permanent magnets 15a, 15b are mounted inside the yokes 14a, 14b, and the blade 12 is arranged between the permanent magnets 15a, 15b so that the blade 12 is loosely inserted.

On the side of the blade 12 facing the permanent magnet 15a, a hollow focus drive coil 16a wound in a substantially rectangular tube shape is installed so that the openings at both ends thereof are directed in the focus direction. . On the side surface of the blade 12 facing the permanent magnet 15a, hollow tracking drive coils 17a, wound around a rectangular tube, respectively, are provided on both sides of the focus drive coil 16a.
Reference numeral 17a is installed with its both end openings oriented substantially in the tracking direction.

On the other hand, the permanent magnet 15b of the blade 12
A hollow focus drive coil 16b wound in a substantially quadrangular cylindrical shape is also installed on the side opposite to the above so that the openings at both ends thereof are oriented in the focus direction. Further, on the side surface of the blade 12 facing the permanent magnet 15b,
A hollow tracking drive coil 1 wound on each side of the focus drive coil 16b in a substantially rectangular cylindrical shape.
7b, 17b are installed with their both ends open in the tracking direction.

Here, the blade 12 is used as a permanent magnet 15
a and 15b are loosely inserted between the permanent magnets 15a, that is, the focus driving coil 1
6a and the tracking drive coils 17a, 17a, the two ends of the tracking drive coil 17a
a, 17a are set so as to face the substantially central portions.

Similarly, the blade 12 is
5a, 15b, the two ends of the permanent magnet 15b in the width direction of the permanent magnet 15b, that is, both ends in the direction in which the focus drive coil 16b and the tracking drive coils 17b, 17b are arranged, are respectively connected to the tracking drive coil 1.
7b and 17b are set so as to face substantially the center portions.

Further, the mounting base 13 has inner yokes 18a and 18b projecting from the bottom surface 13a thereof so as to face the permanent magnets 15a and 15b, respectively. Then, the blades 12 are fixed to the permanent magnets 15a, 15a.
b, the inner yoke 18 is inserted into the hollow portions of the focus drive coils 16a and 16b.
a and 18b are loosely inserted, respectively, and the permanent magnets 15a and 15b
b to form a magnetic path.

For this reason, the focus driving coil 16
By supplying a drive signal for focus control to a and 16b, a drive force is generated on the blade 12 so that the objective lens 11 is moved in the focus direction indicated by the arrow Z in the figure. In addition, the tracking drive coil 1
By supplying a drive signal for tracking control to 7a and 17b, the objective lens 11 is rotated by a rotating shaft 12a described later.
A driving force is generated on the blade 12 so as to rotate in the direction indicated by the arrow X in FIG.

Here, of the mounting base 13,
A pair of support columns 19a and 19b are formed to protrude from the bottom surface 13a opposite to the end facing the objective lens 11. The pair of support columns 19a and 19b are formed with a pair of through holes 20a and 20a formed in the support member 20 formed in a substantially columnar shape.
20b, the support member 20
Is fixed to the mounting base 13.

One end of a leaf spring 12b made of a metal material is embedded in the support member 20. The other end of the leaf spring 12b is embedded in a holding member 12c bonded to the blade 12. Therefore, the blade 12 can move in the focus direction within a range where the leaf spring 12b can be shifted by its elastic force.

The holding member 12c is made of a synthetic resin material having an elastic force, and has a hinge portion 12d narrowed in the width direction. For this reason, the blade 12 is rotatable in the horizontal direction about the rotation shaft 12a by bending of the hinge portion 12d. The rotation direction of the blade 12 corresponds to the tracking direction. Note that a balancer 12e is attached to the blade 12 to smoothly rotate the blade 12 in the tracking direction.

Further, a base end 21a of a flexible substrate 21 is attached to the support member 20, as shown in FIG. The flexible board 21 has a terminal portion 21b formed at the distal end thereof which is connected to the focus drive coils 16a and 16b and the tracking drive coils 17a and 17b. The base end 21a of the flexible substrate 21 is
6a, 16b and tracking drive coils 17a, 17
b is connected to a circuit (not shown) for generating a drive signal to be given to b.

Next, the attachment of the focus drive coil 16b and the tracking drive coil 17b to the blade 12 will be described with reference to FIG. The attachment of the focus drive coil 16a and the tracking drive coil 17a to the blade 12 has the same configuration, and a description thereof will be omitted.

That is, the permanent magnet 1 of the blade 12
5b, the focus drive coil 16b
A recess 22 is formed in which is fitted. This recess 22
The flanges 22a and 22b which protrude inward from each other are formed at the lower end in the drawing of the opposed wall surfaces. For this reason, the focus drive coil 16b
It is positioned by the flanges 22 a and 22 b and the recess 22 and is attached to the blade 12.

On the side of the blade 12 facing the permanent magnet 15b, tracking driving coils 17b, 17b are provided.
b of two pairs of ribs 23a,
23b is protruded. Therefore, the tracking drive coils 17b, 17b are positioned by being fitted to the ribs 23a, 23b, and are attached to the blade 12.

According to the objective lens driving device configured as described above, first, on both sides of the focus driving coil 16b, the focus driving coil 16b is sandwiched.
Since the pair of tracking drive coils 17b, 17b are arranged, the distance between the permanent magnet 15b and the inner yoke 18b can be shortened. For this reason, the gap magnetic flux density can be increased, so that the focus drive sensitivity can be efficiently increased with power saving, which is advantageous, for example, during double-speed reproduction.

This can be similarly explained in the relationship between the focus drive coil 16a and the tracking drive coils 17a, 17a. In the following description, the focus drive coil 16b side will be mainly described, but it goes without saying that the same applies to the focus drive coil 16a side.

The tracking drive coils 17b, 1
7b are ribs 23a, 23b formed on the blade 12.
And affixed directly to the blade 12, so that positioning and workability with much higher accuracy than the conventional configuration in which the tracking drive coils 17b and 17b are affixed to the focus drive coil 16b. Improvement can be achieved.

Further, since the ribs 23a and 23b each have two protruding pieces formed in parallel, it is possible to contribute to weight reduction. Further, by utilizing the elastic action of the two projecting pieces, the workability of attaching the tracking drive coils 17b, 17b can be further improved. In particular, temporary fixing for attaching the tracking drive coils 17b, 17b can be facilitated.

Further, since the focus driving coil 16b is always located at the same position structurally by the flanges 22a and 22b of the concave portion 22, the productivity of the optical head device can be remarkably improved.

Further, the flange portions 22a and 22b for positioning the focus drive coil 16b are made to protrude more than the thickness of the focus drive coil 16b.
The leading end in the projecting direction reaches the hollow portion of the focus drive coil 16b, and when the blade 12 moves by a predetermined amount in the tracking direction, the focus drive coil 16b
If it is set so that it comes into contact with the inner yoke 18b before b, it serves as a stopper in the tracking direction of the blade 12, and the focus drive coil 16b can be protected.

Each of the tracking drive coils 17a, 17a arranged on both sides of the focus drive coil 16b
As shown in FIG. 1, each has a slope so that the side adjacent to the focus drive coil 16b is close to the permanent magnet 15b and the side opposite to the side adjacent to the focus drive coil 16b is separated from the permanent magnet 15b. It is installed on the blade 12.

As described above, the tracking drive coil 17
By arranging the a and 17a, no matter where the blade 12 is in the tracking direction, as shown in FIG.
With respect to the magnetic field emitted from the permanent magnet 15b and returned to the permanent magnet 15b via the yoke 14b, the force generated in the tracking drive coils 17a, 17a effectively acts to rotate the blade 12 in the tracking direction. .

However, the tracking drive coil 17
As shown in FIG. 6, if the a and 17a are not tilted and arranged in a straight line with the focus drive coil 16b, the force generated in the tracking drive coils 17a and 17a varies depending on the position of the blade 12 in the tracking direction. Will happen. It should be noted that the present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the scope of the invention.

[0045]

As described in detail above, according to the present invention,
A very good objective lens driving device having a structure capable of contributing to the reduction in size and weight of the optical head device itself and capable of efficiently driving the objective lens in the focusing direction and the tracking direction with power saving, respectively, and a very good objective lens driving device. An optical head device having the same can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing details of a mounting base in the embodiment.

FIG. 3 is an exploded perspective view showing details of a leaf spring in the embodiment.

FIG. 4 is an exploded perspective view showing details of a drive coil in the embodiment.

FIG. 5 is a diagram showing a distribution state of a magnetic field in the embodiment.

FIG. 6 is a diagram showing a distribution state of a magnetic field in the embodiment.

FIG. 7 is a plan view showing a conventional objective lens driving device.

[Explanation of symbols]

 11: Objective lens, 12: Blade, 13: Mounting base, 14a, 14b: Yoke, 15a, 15b: Permanent magnet, 16a, 16b: Focus drive coil, 17a, 17b: Tracking drive coil, 18a, 18b: Inner yoke, 19a, 19b: support column, 20: support member, 21: flexible substrate, 22: recess, 23a, 23b: rib.

Claims (6)

[Claims] 1. An objective lens for converging laser light emitted from a light source on an optical disk, a magnetic circuit for driving the objective lens in a radial direction and a normal direction of the optical disk, the objective lens and the magnetic circuit An objective lens driving device comprising: a blade portion to which the magnetic circuit is fixed, wherein the magnetic circuit includes a magnet, a yoke provided to face the magnet, and a first yoke fixed to the blade portion and into which the yoke is loosely inserted. An objective lens driving device, comprising: a magnetic circuit comprising: a coil; and a second coil fixed to the blade section and juxtaposed along a surface of the first coil facing the magnet. 2. An objective lens for converging laser light emitted from a light source onto an optical disk, a magnetic circuit for driving the objective lens in a radial direction and a normal direction of the optical disk, the objective lens and the magnetic circuit An objective lens driving device comprising: a blade section to which the coil section is fixed; wherein the blade section includes a locking means for determining the position of the coil section in the normal direction at the fixing section to which the coil section is fixed. An objective lens driving device, which is a blade unit. 3. The second coil according to claim 1, wherein one end adjacent to the first coil is disposed close to the magnet, and the other end is separated from the magnet. 2. The objective lens driving device according to 1. 4. The method according to claim 1, wherein the second coil is formed in a hollow, substantially cylindrical shape, and the blade portion is provided with a rib for fitting and positioning the hollow portion of the second coil. The objective lens driving device according to claim 1, wherein 5. The objective lens driving device according to claim 1, wherein the second coil is provided on both sides of the first coil so as to face the magnet. 6. An optical head device comprising at least a light source for emitting laser light and the objective lens driving device according to claim 1 or 2.