JP2001184683A - Objective lens driving device and disk device using the same - Google Patents

Abstract

(57) Abstract: An object of the present invention is to suppress an increase in lens tilt due to a shift in a tracking direction between a magnetic circuit and a movable part in an objective lens driving device. The magnetic yoke has a first yoke for assembling a fixed portion that supports a movable portion, and a second yoke for assembling a magnet. The first yoke with the fixed portion attached thereto, and the magnet with the magnet attached thereto. The second yoke and the second yoke constitute a closed magnetic circuit surrounding a part of the focusing coil, and the position of the second yoke with the magnet attached thereto with respect to the first yoke with the fixed portion attached thereto can be adjusted in the tracking direction. The magnetic circuit is configured as described above.

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 used for a recording and / or reproducing device for an optical disk, a magneto-optical disk, and the like, and a disk device equipped with the objective lens driving device.

[0002]

2. Description of the Related Art In recent years, high-density recording has been promoted in an optical disk device such as a DVD or a magneto-optical disk device, and a higher numerical aperture (N.D.
A.) has been used. When the optical axis of the objective lens is inclined with respect to the recording / reproducing surface of the disk, coma aberration and astigmatism occur when the convergent light beam passes through the disk substrate. Since coma is proportional to the cube of the numerical aperture of the objective lens and astigmatism is proportional to the square of the numerical aperture of the objective lens, the optical axis of the objective lens relative to the recording / reproducing surface of the disk increases as the numerical aperture increases. Is smaller. Therefore, it is very important to suppress the inclination of the optical axis of the objective lens with respect to the recording / reproducing surface of the disk.

On the other hand, as an objective lens driving device mounted on an optical disk device or a magneto-optical disk device, a two-axis orthogonal translation type in which a movable portion for holding an objective lens is supported by an elastic support member, has conventionally been used. Many are used. This configuration has the advantage that the device can be manufactured compactly and at low cost, but has the problem that the rigidity around the elastic support member is low, so that when the moment around this occurs, the objective lens is easily tilted. Therefore, in the two-axis orthogonal translation type objective lens driving device, it is important to reduce the lens tilt. To solve the above problem, Japanese Patent Laid-Open No. 10-31829 discloses a magnetic circuit configured to cancel the moment generated in the focusing coil by the moment generated in the tracking coil, thereby reducing the lens tilt of the objective lens driving device. ing.

[0004]

FIG. 11 is an external perspective view showing an example of a widely used two-axis orthogonal translation type objective lens driving device. Objective lens drive 101
Is mounted on a feed base (not shown) parallel to the information surface of an optical information recording medium such as a disk and movable in the radial direction (tracking direction 14).

[0005] The objective lens 1 and the lens
A casing coil 3 (hereinafter referred to as an AF coil), a tracking coil 4 (hereinafter referred to as a TR coil), and a small substrate 5 are assembled to form a movable portion 51 of the objective lens driving device. The lens holder 2 is supported by four elastic support members 11 joined to the small substrate 5, whereby the movable section 51 maintains its posture and keeps the focusing direction 15 (hereinafter, referred to as AF direction) and It is possible to move in the tracking direction 14 (hereinafter, referred to as TR direction).

[0006] The fixed portion holder 9 includes the elastic support member 1.
A fixed part substrate 10 to which the other end of 1 is joined is assembled. Further, a viscoelastic material 13 is provided on the fixed part holder 9, thereby reducing unnecessary vibration of the elastic support member 11.

At a predetermined position of the first yoke 6, two magnets 8
A second yoke 7 shown by a dotted line is assembled, and constitutes a magnetic circuit of the present driving device. At a predetermined position of the first yoke 6, a fixed part holder 9 that supports the movable part is assembled with a screw 12. As described above, the conventional objective lens driving device 101 has a configuration in which the magnet 8 and the fixed part holder 9 that supports the movable part 51 are assembled at a predetermined position of the first yoke 6.

In the following, AF direction 15 and TR direction
A direction 16 perpendicular to 14 is described as an elastic support member direction.

FIG. 12 is a plan view showing the positional relationship between the magnetic circuit and the movable part 51 when no current is flowing through the coil. Here, the center of the magnet 8 and the yoke 6 in the TR direction 14 is a magnetic circuit center 53, and the center of the movable section 51 in the TR direction 14 (= center of the AF coil 3) is a movable section center 52.

Normally, when the objective lens driving device is assembled as designed, the center 53 of the magnetic circuit coincides with the center 52 of the movable portion in the TR direction 14 as shown in FIG. However, in reality, there are dimensional errors and assembly errors of parts, and the positional relationship between the magnetic circuit and the movable portion 51 does not match the design drawing. That is, FIG.
As shown in (b) and (c), inconsistency occurs in that the center 53 of the magnetic circuit is shifted to the TR direction 14 and to the left or the TR direction 14 and to the right with respect to the movable part center 52.

In the following, for the sake of simplicity, the magnetic circuit center 53 will be described.
Except that the movable part center 52 and the movable part center 52 are displaced in the TR direction 14, taking the objective lens driving device all assembled to the designed dimensions as an example, when the movable part 51 is displaced in the AF direction 15, the AF coil 3, The principle of generating a moment around the elastic support member direction 16 will be described. Here, it is assumed that the physical property values of each component are also as specified.

FIGS. 13A to 13C are diagrams schematically showing the movable portion 51 as viewed from the direction 16 of the elastic support member. The positional relationship between the movable portion 51 and the magnetic circuit is shown in FIG. ) To (c). In the figure, in the middle part, when the movable part 51 is in the neutral position (corresponding to the case where no current is flowing to the AF coil), the upper part supplies current only to the AF coil, and
Is displaced to the upper side in the AF direction 15 from the neutral position, and the lower part shows the case where the movable part 51 is displaced to the lower side in the AF direction 15 from the neutral position. (A)-
(C) In both cases, the inclination in the radial direction at the neutral position is zero.

Here, the center of support of the movable portion 51: C, that is, the intersection of the diagonal lines of the four junctions between the movable portion 51 and the elastic support member 11 coincides with the center of gravity of the movable portion, and further, in the TR direction. It is assumed that 14 coincides with the center 52 of the movable part.
When the thrust in the AF direction generated in the AF coil is represented by one point of thrust, the position of the point is the center of the thrust of the AF coil: PAF, and the representative thrust is the AF thrust:
FAF. In this magnetic circuit configuration, the thrust center of the AF coil: PAF is substantially the center of the magnetic circuit in the TR direction 14.
Matches 53.

[0014] As shown in FIG.
When the center 53 of the movable portion coincides with the center 52 of the movable portion, the thrust center of the AF coil: PAF and the support center of the movable portion: C are in the TR direction 14.
Therefore, even when the movable portion 51 is displaced in the AF direction 15, a moment M around the elastic support member direction 16 is not generated.

On the other hand, as shown in FIG. 12B, when the center 53 of the magnetic circuit is displaced to the left from the center 52 of the movable part, when the movable part 51 is displaced upward in the AF direction 15, When a clockwise moment (M :−) is generated in the movable part and the movable part 51 is displaced downward in the AF direction 15,
A counter-clockwise moment (M: +) is also generated in the movable part.

In the case where the center 53 of the magnetic circuit is shifted to the right side of the center 52 of the movable part as shown in FIG.
A moment in a direction opposite to that in FIG. 13B is generated.

FIG. 14 shows the amount of displacement in the AF direction and FIG.
6 is a graph showing the relationship between the moment shown in (a) to (c): M and the inclination of the movable portion 51 generated in the radial direction. In the case (a) where the center 53 of the magnetic circuit coincides with the center 52 of the movable part, even if the movable part 51 is displaced in the AF direction 15, no tilt in the radial direction occurs. In contrast, the magnetic circuit center 53
In the cases (b) and (c), in which the movable part 51 and the movable part center 52 are displaced in the TR direction 14, the radial inclination increases as the displacement amount of the movable part 51 in the AF direction 15 increases. Also, according to the principle of occurrence of the tilt in the radial direction, the center of the magnetic circuit in the TR direction 14 is determined.
The greater the amount of deviation between 53 and the center 52 of the movable part, the greater the radial inclination that occurs.

As described above, the center 53 of the magnetic circuit and the center 52
When there is a deviation between the moving part 51 and the moving part 51, the movable part 51 is inclined in the radial direction. In contrast, the conventional objective lens driving device 10
In a configuration in which the magnet 8 and the fixed part holder 9 are assembled at a predetermined position of the first yoke 6 as shown in FIG.
It is not possible to correct the displacement between the moving part 52 and the center 52 of the movable part, and thus it is not possible to suppress the occurrence of the above-mentioned inclination in the radial direction.

The inclination in the radial direction is determined by the AF coil 3
When a current flows only in the AF coil 3, the moment occurs in the AF coil 3, and thus the radial inclination cannot be suppressed even if the configuration of the magnetic circuit disclosed in the above publication is adopted. This is because, under the above conditions, the current of the TR coil 4 is zero, and no moment is generated in the TR coil 4 to offset the moment generated in the AF coil 3.

An object of the present invention has been made in view of the above problems, and has a configuration almost the same as that of the conventional device, and makes it possible to adjust the positional relationship between the magnetic circuit and the movable portion 51 in the TR direction 14. As a result, the lens tilt is small,
Another object of the present invention is to provide a compact and low-cost objective lens driving device and a disk device.

[0021]

In order to solve the above-mentioned problems, an objective lens driving apparatus according to the present invention comprises an objective lens for recording or reproducing optical information on a disk-shaped recording medium, and an objective lens for holding the objective lens. A lens holder, a focusing coil provided to drive the objective lens in the focusing direction, a tracking coil provided to drive the objective lens in the tracking direction, and opposing these coils. Magnetic yoke having magnets assembled so as to form a magnetic circuit, an elastic supporting member for elastically supporting the lens holder at one end, and supporting the other end of the elastic supporting member. The magnetic yoke has a first yoke for assembling the fixing portion, and a second yoke for assembling the magnet, and the first yoke, The second yoke constitutes a closed magnetic circuit surrounding a part of the focusing coil, and the position of the second yoke with respect to the first yoke can be adjusted in the tracking direction. Objective lens drive.

A disk device for recording and / or reproducing information on / from an information recording disk includes a motor for rotating the information recording disk at a predetermined number of revolutions and an optical head for recording and / or reproducing information. The optical head is mounted on a means for coarsely moving the information recording disk in a radial direction, and the optical head comprises an objective lens for recording or reproducing optical information on the information recording disk; A lens holder for holding the lens, a focusing coil provided for driving the objective lens in the focusing direction, a tracking coil provided for driving the objective lens in the tracking direction, and facing these coils. And a magnetic yoke in which a magnet is assembled so as to form a magnetic circuit, and the lens holder is elastically cantilevered at one end. And an elastic support member that includes a fixing portion for supporting the other end of the elastic support member, wherein the magnetic yoke,
A first yoke for assembling the fixing portion, and a second yoke for assembling the magnet, the first yoke and the second yoke constitute a closed magnetic circuit surrounding a part of the focusing coil, A disk device equipped with an objective lens driving device, wherein a position of the second yoke with respect to the first yoke can be adjusted in a tracking direction.

Further, a disk device equipped with the objective lens driving device configured as described above may be used.

[0024]

Embodiments of the present invention will be described below in detail.

The objective lens driving device of this embodiment is shown in FIG.
Since the configuration is almost the same as the conventional example shown in FIG.
11 are given the same reference numerals, and different parts will be described in detail. FIG. 5 is an external perspective view showing an example of a disk device on which the objective lens driving device 111 of the present invention is mounted. The disk device 20 performs an operation of sending the disk 21 placed on the disk tray 23 into (or out of) the device by a disk loading mechanism (not shown). Also, the disk 21 sent to the device
Is mounted on a turntable 22 integrally formed with the rotating shaft of the spindle motor, and is suction-fixed by a clamper 24 attached to a clamper holder 25.

The disk 21 is rotated at a predetermined number of revolutions by the spindle motor, and the information recorded on the disk 21 is read out by the head 29 mounted on the unit mechanical chassis 26. The head 29 mounted on a feed base (not shown) that can be roughly moved in the loading direction (TR direction) 14 of the disc tray 23 includes an objective lens driving device 111.
It is equipped with.

The unit mechanical chassis 26 is mounted on a mechanical base 27 via vibration isolating legs 28 made of an elastic member. Further, a bottom cover 30 and a top cover 31 are attached to the entire apparatus.

FIG. 1 is an external perspective view of the objective lens driving device 111 of the present invention, and FIG.
FIG. 4 is a perspective view showing a state before being assembled to the device.

An objective lens 1, an AF coil 3, a TR coil 4, and a small substrate 5 are mounted on the lens holder 2, and are supported by four elastic support members 11.

A fixed part holder 9 to which a fixed part substrate 10 is mounted is attached to the first yoke 6 by screws 12, and the other end of the elastic support member 11 is fixed to the fixed part substrate 10. On the other hand, a magnet 8 is mounted on the second yoke 7, and the second yoke 7 is in the TR direction with respect to the first yoke 6.
After the position adjustment of 14, the first yoke 6 is adhered and fixed.

FIG. 3 shows the AF direction 15 and the elastic support member direction 16
, The first yoke 6, the second yoke 7, the magnet 8
FIG. 3 is a cross-sectional view of the AF coil 3. As shown by hatching in the figure, in the magnetic circuit of the objective lens driving device 111 of the present invention, the first yoke 6 and the second yoke 7 constitute a closed magnetic circuit 50 that partially surrounds the AF coil 3. ing. In addition,
In the present invention, when the second yoke 7 is not provided in the conventional objective lens driving device 101, that is, the magnetic circuit in which the yoke surrounds a part of the AF coil 3 and is not closed is an open magnetic circuit,
In FIG. 1, when the second yoke 7 is provided, and a magnetic circuit in which the yoke surrounds a part of the AF coil 3 and is closed as in the magnetic circuit shown in FIG. However, the case where a very small gap layer or a non-magnetic layer such as an adhesive is present in the magnetic circuit also corresponds to the closed magnetic circuit according to the present invention.

FIG. 4 is a perspective view showing the shapes of the second yoke 7, the first yoke 6, and the magnet 8 (however, in this drawing, a part of the parts is cut). As shown in the figure, the first yoke 6 is provided with a concave portion 19, and the second yoke is provided with a convex portion 18. By inserting the convex portion 18 into the concave portion 19, the elastic support of the second yoke is provided. The positioning in the member direction 16 is performed. Further, the length of the concave portion 19 with respect to the TR direction 14: L
The relationship between the bottom and the length of the projection 18: Ltop is as follows.

Lbottom> Ltop Therefore, the position of the second yoke 7 can be moved in the TR direction 14 with respect to the position of the first yoke 6, and the length for which the position can be adjusted is Lbottom-Ltop. is there.

The effect of reducing the inclination of the objective lens in the radial direction will be described below by taking the simplified case shown in FIGS. Magnetic circuit center in objective lens drive
The positional relationship between 53 and the center 52 of the movable part is shown in FIG.
If the current is shifted as shown in FIG. 14C, when a current is applied to the AF coil 3, as shown in FIGS. 14B and 14C,
Radial tilt occurs. However, by adjusting the position of the second yoke 7 to which the magnet 8 is assembled in the TR direction 14, the center 53 of the magnetic circuit and the center 52 of the movable portion can be matched as shown in FIG. Part 51 in the AF direction
Fig. 14 shows the radial inclination that occurs when displaced to 15
It can be set to zero as shown in FIG.

An example of a method of adjusting the position of the second yoke when assembling the objective lens driving device 111 will be described below.

After arranging the second yoke 7 at a predetermined position on the first yoke 6, a current is applied only to the AF coil 3. Then, the inclination of the movable portion 51 in the radial direction is monitored, and the position of the second yoke 7 is adjusted in the TR direction 14 so that the absolute value of the inclination in the radial direction is minimized. Next, the second yoke is fixed to the first yoke 6 using an adhesive or the like. Thus, the adjustment of the position of the second yoke 7 is completed.

In the actual objective lens driving device, in addition to the displacement of the magnetic circuit and the movable portion 51 in the TR direction 14, for example, variations in the parallelism, length, and spring constant of the four elastic support members 11 There are various variations such as variations in magnet size and magnet properties. For this reason, the position where the inclination in the radial direction becomes minimum is determined by the center 53 of the magnetic circuit and the center 52
Is not always the same point. Therefore, it is desirable to adjust the position of the second yoke 7 while applying a current to the AF coil 3 and monitoring the inclination of the movable portion 51 in the radial direction.

As described above, the objective lens driving device 111 of the present invention has almost the same configuration as the conventional device 101, and the tilt in the radial direction can be effectively reduced by simple adjustment.

When adjusting the positional relationship between the movable part 51 and the magnetic circuit, other than the configuration of adjusting the position of the second yoke 7 to which the magnet 8 is assembled as in the present invention, (1) the movable part 51 is supported. The position of the fixed part holder 9 is adjusted with respect to the first yoke 6. (2) The first yoke 6 is divided into a plurality of parts, and the position of the first yoke in which the magnet 8 is mounted is different from the position where the fixed part holder 9 is mounted. The first yoke may be adjusted.

However, regarding (1), the first yoke 6
There is a disadvantage that the relative position between the lens and the objective lens 1 is changed by moving the fixed part holder 9, which adversely affects the characteristics of the optical system. In addition, the method (2) has a disadvantage that the number of components increases, the size of the objective lens driving device increases, and the like.

Therefore, the configuration for adjusting the position of the second yoke 7 to which the magnet 8 is mounted, with respect to the first yoke 6 to which the fixing portion holder 9 is mounted, which is employed in the objective lens driving device of the present invention, is as follows. Is easy, and compared with the conventional objective lens driving device, there is no problem such as adverse effects on the optical system, increase in the number of parts, and increase in the size of the device.
It can be said that this is the most advantageous configuration.

In the embodiment of the present invention, the second yoke is positioned by providing a convex portion on the second yoke and a concave portion on the first yoke, and inserting the convex portion into the concave portion. The second yoke 7 may be positioned using a mechanism. Further, the position of the second yoke 7 is
After adjusting to 4, the second yoke 7 and the first yoke 6 are bonded together, and the second yoke 7 and the fixed part holder 9 are bonded.
Alternatively, it is natural that the first yoke 6 and the magnet 8 may be bonded.

Next, another embodiment according to the present invention will be described. FIG. 6 is an external perspective view showing an example in which the present invention is applied to an objective lens driving device having magnetic circuits on both sides of the objective lens. FIG. 7 is a perspective view showing a state before the second yoke 7 is assembled to the first yoke 6.

An objective lens 1, an AF coil 3, and a TR coil 4 are assembled to the lens holder 2, and are supported by four elastic support members 11.

The first yoke 6 is provided with a fixed part holder 10 to which the fixed part substrate 10 is assembled by a spring 17 and an adhesive (not shown).
9 is assembled, and the other end of the elastic support member 11 is fixed to the fixed part substrate 10.

On the other hand, the magnet 8 is assembled to the second yoke 7, and the position of the second yoke 7 can be adjusted in the TR direction 14 with respect to the first yoke 6.

FIG. 8 shows the AF direction 15 and the elastic support member direction 16.
, The first yoke 6, the second yoke 7, the magnet 8
FIG. 3 is a cross-sectional view of the AF coil 3. In the magnetic circuit of the objective lens driving device 121 of the present invention, a closed magnetic circuit 50 surrounding a part of the AF coil 3 by the first yoke 6 and the second yoke 7 is shown as shown by hatching in FIG. It is configured on both sides of the solid objective lens 1.

FIG. 9 is a perspective view showing the shapes of the second yoke 7, the first yoke 6, and the magnet 8 (however, in this drawing, a part of the component is cut). Objective lens drive
In 121, the concave portion 32 is formed in the second yoke 7, and the convex portion 3 is formed in the first yoke 6.
3 so that the elastic support member direction 16 of the second yoke 7 is
Is positioned. By setting the length of the concave portion 32> the length of the convex portion 33 in the TR direction, the second yoke 7 can be adjusted in the TR direction 14.

The objective lens driving device in which the magnetic circuits are arranged on both sides of the objective lens also has the above configuration,
By adjusting the position of the second yoke 7 to which the magnet 8 is attached in the TR direction 14, the objective lens driving device shown in FIG.
Similarly to 111, the inclination of the movable portion 51 in the radial direction can be significantly reduced.

The shapes of the second yoke 7 and the first yoke 6 may be the shapes shown in FIG. 10 instead of the shapes shown in FIG.

As described above, even in an objective lens driving device having a magnetic circuit on both sides of the objective lens, the inclination in the radial direction can be greatly reduced by applying the configuration of the present invention.

The same effect can be obtained when an objective lens system in which an optical element such as a wave plate and a dichroic filter is added to the objective lens instead of the objective lens described in the above-described embodiment. .

Further, the disk device of the present invention can be used for CD-ROM, DVD-
The present invention is not limited to disk devices such as ROM and DVD-RAM, but is also applied to magneto-optical disk devices and the like.

[0054]

As described above, in the objective lens driving device according to the present invention, the tilt of the movable portion in the radial direction can be effectively reduced without adversely affecting the optical system due to the adjustment. Further, the configuration of the present objective lens driving device is substantially the same as the configuration of the conventional objective lens driving device, so that the present device is small in size and low in cost.

[Brief description of the drawings]

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

FIG. 2 is an external perspective view showing an embodiment of an objective lens driving device according to the present invention.

FIG. 3 is a sectional view showing shapes of a yoke, a magnet, and a coil of the objective lens driving device according to the present invention.

FIG. 4 is a perspective view showing shapes of a yoke and a magnet of the objective lens driving device according to the present invention.

FIG. 5 is an external perspective view showing an embodiment of a disk drive according to the present invention.

FIG. 6 is an external perspective view showing an embodiment of an objective lens driving device according to the present invention.

FIG. 7 is an external perspective view showing an embodiment of an objective lens driving device according to the present invention.

FIG. 8 is a sectional view showing shapes of a yoke, a magnet, and a coil of the objective lens driving device according to the present invention.

FIG. 9 is a perspective view showing shapes of a yoke and a magnet of the objective lens driving device according to the present invention.

FIG. 10 is a perspective view showing shapes of a yoke and a magnet of the objective lens driving device according to the present invention.

FIG. 11 is an external perspective view showing a form of a conventional objective lens driving device.

FIG. 12 is a plan view illustrating a positional relationship between a movable section and a magnetic circuit.

FIG. 13 is a schematic diagram illustrating that a moment is generated in a movable portion.

FIG. 14 is a graph showing the relationship between the displacement of the movable part in the AF direction and the lens tilt.

[Explanation of symbols]

101: Conventional objective lens driving device, 111: Objective lens driving device of the present invention, 121: Objective lens driving device of the present invention,
DESCRIPTION OF SYMBOLS 1 ... Objective lens, 2 ... Lens holder, 3 ... Focusing coil, 4 ... Tracking coil, 5 ... Small board, 6 ...
1st yoke, 7 ... second yoke, 8 ... magnet, 9 ... fixed part holder, 10 ... fixed part substrate, 11 ... elastic support member, 12 ...
Screw, 13: Viscoelastic material, 14: Tracking direction, 15
... Focusing direction, 16 ... Elastic support member direction, 17
... spring, 18 ... second yoke projection, 19 ... first yoke recess, 20 ... disk device, 21 ... disk, 22 ... tar
Table, 23 ... Disc tray, 24 ... Clamper, 25 ... Clamper holder, 26 ... Unit mechanical chassis, 27 ... Mechanical base, 28 ... Vibration-proof legs, 29 ... Head, 30 ... Bottom cover, 31 ... Top cover, 32 ...
Second yoke concave portion, 33: first yoke convex portion, 50: closed magnetic circuit, 51: movable portion, 52: movable portion center, 53: magnetic circuit center.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D118 AA13 BA01 DC03 EA02 EB13 EC02 ED05 ED07 EE01 FA29 FB20

Claims (2)

[Claims] 1. An objective lens for recording or reproducing optical information on a disk-shaped recording medium, a lens holder for holding the objective lens, and a lens holder for driving the objective lens in a focusing direction. A focusing coil, a tracking coil provided to drive the objective lens in the tracking direction, and a magnetic yoke arranged to face these coils and assembled with a magnet to form a magnetic circuit. An elastic support member that elastically cantileverly supports the lens holder at one end, and a fixing portion that supports the other end of the elastic support member, wherein the magnetic yoke includes a first yoke on which the fixing portion is assembled. And a second yoke for assembling the magnet. The first yoke and the second yoke constitute a closed magnetic circuit surrounding a part of the focusing coil. Rutotomoni, for the first yoke, the position of the second yoke, the objective lens driving device is characterized in that configured to be adjusted in the tracking direction. 2. A disk drive for recording and / or reproducing information on an information recording disk, comprising: a motor for rotating the information recording disk at a predetermined rotation speed; and an optical head for recording and / or reproducing information. The optical head is mounted on a means for coarsely moving the information recording disk in a radial direction, and the optical head includes an objective lens for recording or reproducing optical information on the information recording disk; A lens holder for holding the objective lens, a focusing coil provided for driving the objective lens in the focusing direction, a tracking coil provided for driving the objective lens in the tracking direction, And a magnetic yoke in which magnets are assembled so as to form a magnetic circuit, and the lens holder is elastically cantilevered at one end. And an elastic support member that includes a fixing portion for supporting the other end of the elastic support member, wherein the magnetic yoke,
A first yoke for assembling the fixing portion, and a second yoke for assembling the magnet, the first yoke and the second yoke constitute a closed magnetic circuit surrounding a part of the focusing coil, A disk device equipped with an objective lens driving device, wherein a position of the second yoke with respect to the first yoke can be adjusted in a tracking direction.