JP3431802B2 - Objective lens drive - Google Patents

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 an optical pickup used for reproducing an optical recording disc such as a CD (compact disc) or a DVD (digital video disc). More specifically, the present invention relates to a structure for preventing rattling of a lens holder holding an objective lens on a holder supporting member.

[0002]

2. Description of the Related Art As an objective lens driving device of an optical pickup used for reproducing an optical recording disk such as a CD or a DVD, a lens holder holding an objective lens and having an axial hole, and a lens holder inserted into the axial hole. And a holder supporting member having a holder support shaft that supports the lens holder so as to be rotatable in the tracking direction and movable in the focusing direction, and the lens holder is moved along the holder support shaft and is rotated around the holder support shaft. A shaft sliding type having a magnetic circuit is known.

In the objective lens driving device of this structure,
In order to stabilize the lens holder at a neutral position with respect to the holder support shaft, Japanese Patent Publication No. 7-31814 proposes a magnetic spring method using a magnetic circuit. With this method,
A magnet is attached to the holder support member, and a magnetic piece is attached to the lens holder so as to face the magnet. The magnetic piece is magnetically attracted to the magnet to hold the lens holder in the neutral position. .

[0004]

In such a shaft sliding type objective lens driving device, since the holder support shaft is made of metal, it can be accurately formed by machining. However, since the lens holder is a resin molded product, the accuracy is improved so much. I can't. Therefore, rattling is likely to occur between the holder support shaft and the shaft hole, and if such rattling occurs, the holder support shaft is unevenly contacted with the inner peripheral surface of the shaft hole. In this case, the lens holder may not be slid and rotated smoothly. In addition, such rattling may cause double resonance in the lens holder, which may hinder proper driving thereof. Further, the rattling causes the lens holder to tilt with respect to the holder support shaft, that is, the objective lens to tilt, which may deteriorate the optical performance of the optical pickup.

In order to avoid such an adverse effect, the applicant of the present invention previously used a magnet and a magnetic piece which constitute a magnetic spring type neutral position maintaining means in Japanese Patent Application No. 8-71582. , By applying lateral pressure to the lens holder in the direction orthogonal to the holder support shaft as follows,
A structure has been proposed to eliminate rattling between the holder support shaft and the shaft hole.

That is, as shown in FIG. 6A, in order to hold the lens holder 3 in a neutral position with respect to the holder supporting member 4, the holder supporting member 4 has magnets 52, 6 attached thereto.
2 is attached, and a magnet 5 is attached to the lens holder 3.
The magnetic pieces 11 and 12 facing the reference numerals 2 and 62 are attached. Magnetic center 5 of magnets 52 and 62
The magnetic pieces 1 and 61 (center of the magnetic pole) are attached at positions symmetrical with respect to the holder support shaft 45, while the magnetic piece 1
Reference numerals 1 and 12 are arranged so as to be offset from the magnetic centers 51 and 61 by the angle a in the opposite direction with the holder support shaft 4 as the rotation center. Therefore, the magnets 52 and 62 and the magnetic pieces 11 and 12 are
Between the magnetic pieces 11 and 12 and the magnets 52 and 62,
Since the first and second magnetic attraction forces F1 and F2 are generated toward the magnetic centers 51 and 61 of, the resultant force acts on the lens holder 3 as the lateral pressure F. Therefore, since the lens holder 3 is pressed in the direction orthogonal to the holder support shaft 45, the rattling between the shaft hole 34 and the holder support shaft 45 is removed.

However, in the objective lens driving device having this structure, as shown in FIG. 6B, when the lens holder 3 is rotationally driven in the tracking direction (for example, the direction of arrow A), one magnetic piece 11 is magnetized. The magnetic piece 52 moves away from the magnetic center 51, and the other magnetic piece 12 moves toward the magnetic center 62 of the magnet 62. Therefore, the magnetic attraction force F1 acting between the one magnetic piece 11 and the magnet 52 becomes small, and the other magnetic piece 12
Since the magnetic attraction force F2 acting between the magnet 62 and the magnet 62 becomes large, the magnetic attraction forces F1 and F2 of both sides are out of balance, and the direction of the lateral pressure F changes rapidly accordingly. As a result, the proper driving of the lens holder 3 may be hindered and the optical performance of the optical pickup may deteriorate.

Therefore, an object of the present invention is to apply a lateral pressure to a lens holder by using a magnet and a magnetic piece that generate a magnetic attraction force for holding the lens holder at a predetermined neutral position. An object of the present invention is to propose an objective lens driving device that can apply a stable lateral pressure to the lens holder even when the lens holder is driven by improving the arrangement structure of the magnetic pieces.

[0009]

In order to solve the above-mentioned problems, the present invention provides a lens holder that holds an objective lens and has a shaft hole, and a holder support shaft inserted into the shaft hole. A holder supporting member, a magnetic circuit for driving the lens holder along the holder support shaft in the axial direction and around the axial line, and in one of the lens holder and the holder supporting member, a magnetic circuit in the magnetic circuit. Magnetic attraction force that holds the lens holder in a predetermined neutral position in a state where the magnet circuit is not driven and is attached so as to form a pair with only a plurality of magnets polarized in the direction. In an objective lens driving device having a plurality of magnetic pieces generated between
The resultant magnetic attraction force generated between the magnetic piece and the magnet forming a pair with the magnetic piece applies a lateral pressure in a direction orthogonal to the holder support shaft to the lens holder, The magnets and the magnetic pieces are arranged at positions displaced from each other at positions equiangularly spaced, and in each set, the magnetic pieces are arranged so as to face the magnetized polarization line of the magnets. It is characterized by

The magnetic center of the magnet in the present invention means a portion corresponding to the polarization line of polarization when the corresponding surface is polarized and magnetized, and the center position of the magnetized single pole. Means

According to the present invention, when a lateral pressure is applied to the lens holder by using a magnet and a magnetic piece that generate a magnetic attraction force for holding the lens holder in a predetermined neutral position, the magnetic piece is used to apply a magnetic force to the lens holder. Instead of facing the magnetic center of the magnet, the magnetic piece is made to face the magnetic center of the magnet, and in this state, the magnet and the magnetic piece are displaced from the equidistant positions.
The lens holder is arranged so that the lens holder is laterally pressurized. Therefore, as long as the magnetic pieces face the magnetic center of each magnet in each set, when the lens holder is rotated from the neutral position around the axis, all the magnetic pieces have the same rotation direction from the magnetic center of the magnet. Are separated by the same distance. Therefore, when the lens holder is rotated, the magnetic attraction force generated between the magnet and the magnetic piece is reduced by the same amount in any of the groups, so that the magnitude of the magnetic attraction force remains the same in each group. Is. Therefore, even when the lens holder is driven, the lateral pressure generated by combining the magnetic attraction forces is stable with only a slight change in size and direction. It is possible to drive the lens holder properly without rattling.
Further, since the magnet and the magnetic piece that generate the magnetic force for holding the lens holder in the predetermined neutral position in the state where the magnetic circuit is not driven are used, the lateral pressure applied to the lens holder is generated. It is not necessary to add another mechanism for generating this lateral pressure.

In the present invention, since the lateral pressure is generated by disposing the magnet and the magnetic piece facing the magnetic center at a predetermined position, the magnetic attraction force generated between the magnet and the magnetic piece is reduced. Lateral pressure can be generated even if the size is the same in each set. Therefore, the specifications of each magnetic piece can be made common.

In the present invention, the magnetic piece and the magnet are deviated by the same rotation angle in opposite directions from a point-symmetrical position where the magnetic center of the magnet is centered on the support shaft. Two sets are arranged so that

In this case, as the magnet,
A tracking magnet for rotating the lens holder around the axis can be used in the magnetic circuit.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an objective lens driving device of the present invention will be described below with reference to the drawings.

[First Embodiment] (Overall Structure) FIG. 1 is a plan view of an objective lens driving device according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG. Is.

As shown in these figures, the objective lens driving device 1 includes a lens holder 3 holding an objective lens 2,
Holder support member 4 that movably supports the lens holder 3
have. The holder support member 4 has a circular bottom wall 41.
A cylindrical outer yoke 42 that rises at a right angle from the outer peripheral edge of the bottom wall 41, a pair of inner yokes 43 and 44 formed by vertically raising a portion of the bottom wall 41, and the bottom wall 41.
And a holder support shaft 45 which stands upright from the center of the. The inner yokes 43 and 44 may be attached as separate parts without directly cutting and raising a part of the bottom wall 41.

The lens holder 3 is provided with a cylindrical body portion 32 whose upper end is closed by a top plate 31, and a cylindrical bearing portion 33 formed at the center of the body portion 32. Inside the bearing portion 33 is a shaft hole 34 into which the holder support shaft 45 is inserted. The objective lens 2 is attached to the upper surface of the top plate 31.

Between the lens holder 3 and the holder supporting member 4, there is a tracking magnetic circuit for rotating the lens holder 3 around the axis 46 of the holder support shaft 45, and the lens holder 3
A focusing magnetic circuit is configured to move the holder along the holder support shaft 45 in the direction of the axis 46. The tracking magnetic circuit and the focusing magnetic circuit include a pair of tracking drive coils 7 and 8 having the same specifications, a pair of focusing drive coils 9 and 10 having the same specifications, and these drive coils, which are attached to the outer peripheral surface of the lens holder 3. The first and second magnets 5 and 6 of the same specifications are attached to the inner peripheral surface of the outer yoke 42 so as to face each other.

FIG. 3 is a perspective view showing the lens holder 3 taken out. With reference to this figure as well, the first and second tracking drive coils 7 and 8 have a flat shape with a substantially rectangular vertical cross section, and one end face thereof is bonded to the outer peripheral surface of the lens holder 3. There is. The first and second focusing drive coils 9 and 10 extend in the direction of the axis 46 of the holder support shaft 45 with a substantially rectangular cross section, and their outer peripheral surfaces are bonded to the outer peripheral surface of the lens holder 3. The focusing drive coils 9 and 10 are air core coils, and the inner yokes 43 and 44 are located in the air core portions as shown in FIG.

The first and second magnets 5 and 6 are polarized and magnetized in the circumferential direction around the portion where the tracking drive coils 7 and 8 face each other, and the portions where the tracking drive coils 7 and 8 face each other. Are the first and second tracking drive magnet portions 52 and 62.
In the first and second magnets 5 and 6, the facing portions of the focusing drive coils 9 and 10 are magnetized into a single pole,
That is the first and second focusing drive magnet portions 53 and 63. Therefore, the lens holder 3 is controlled in the tracking direction (rotation around the axis 46 of the holder support shaft 45) and focusing by controlling the power supply to the drive coils 7, 8, 9 and 10 through the FPC board 13. Direction (movement in the direction of the axis 46 along the holder support shaft 45).

(Structure of Neutral Position Holding Means) In this embodiment,
In order to generate a magnetic force that holds the lens holder 3 at a predetermined neutral position in a state where the tracking magnetic circuit and the focusing magnetic circuit are not driven, the first and second tracking portions of the outer peripheral surface of the lens holder 3 are generated. The first and second magnetic pieces 11 and 12 having the same specifications are adhered to the inside of the drive coils 7 and 8, respectively.
Reference numerals 1 and 12 denote the first and second tracking drive magnet portions 5 of the first and second magnets 5 and 6, respectively.
It faces 2,62. Therefore, in a state where the tracking magnetic circuit and the focusing magnetic circuit are not driven, the magnetic attraction force generated between the first magnetic piece 11 and the first tracking drive magnet portion 52, and the second magnetic force. The magnetic attractive force generated between the piece 12 and the second tracking drive magnet portion 62 acts to hold the lens holder 3 at a predetermined neutral position set in advance both in the tracking direction and the focusing direction. To do.

(Structure of Side Pressure Applying Means) In the objective lens driving device 1 configured as described above, in this embodiment, the first and second magnetic pieces 11 for generating the magnetic force for holding the lens holder 3 in the neutral position. , 12, and the first and second magnets 5 and 6 (first and second tracking drive magnet portions 52 and 62) are used as they are, in a direction orthogonal to the holder support shaft 45 with respect to the lens holder 3. Is configured to apply the lateral pressure of.

That is, in this embodiment, the first and second magnetic pieces 11, 11 are not driven while the lens holder 3 is being driven.
12 is the magnetic center 5 of the first and second tracking drive magnet sections 52 and 62, respectively.
It is arranged so as to face Nos. 1 and 61 (magnetized polarization line). Here, the first and second tracking drive magnet parts 52 and 62 are point-symmetrical with respect to the holder support shaft 45 at positions where the magnetized polarization lines 51 and 61 face each other with the holder support shaft 45 interposed therebetween. It is arranged at a position deviated from the position in the circumferential direction (direction around the axis 46 of the holder support shaft 45). Therefore, the first and second magnetic pieces 11, 12
Is also arranged at a position deviated from the position of point symmetry about the holder support shaft 45.

Thus, the first and second magnetic pieces 11,
12 and the first and second tracking drive magnet portions 52 and 62 are arranged, the first and second
Between the magnetic piece 11 and the first tracking drive magnet portion 52, the first magnetic piece 11 is attempted to be attracted to a position corresponding to the magnetic center line 51 of the first tracking drive magnet portion 52. The first magnetic attraction force F1 is generated, and the second magnetic piece 12 is magnetized between the second magnetic piece 12 and the second tracking drive magnet portion 62. A second magnetic attraction force F2 that tends to be attracted to a position corresponding to the target center 61 is generated. Here, the first and second magnetic attraction forces F
Both 1 and F2 can be expressed as forces F11 and F12 passing through the axis 46 of the holder support shaft 45.
The vectors of F12 (first and second magnetic attraction forces F1, F2) have the same magnitude, but their directions deviate from the same line. Therefore, the first and second magnetic attraction forces F
Since the resultant force of 1 and F2 acts as a lateral pressure F that presses the lens holder 3 in a direction orthogonal to the holder support shaft 45, rattling does not occur between the holder support shaft 45 and the shaft hole 34.

Further, in this embodiment, when the lens holder 3 is in the neutral position, the first and second magnetic pieces 11 and 12 are magnetically coupled to the first and second tracking drive magnet portions 52 and 62, respectively. Since the lens holder 3 is at a position facing the centers 51 and 61, as shown in FIG. 4, when the lens holder 3 is rotationally driven in the tracking direction (for example, the direction of arrow A), the first and second magnetic pieces 11 and 12 are , Both the first and second tracking drive magnet units 5
It is separated from the magnetic centers 51 and 61 of the two 62 by the same distance in the same rotation direction. Therefore, even if the lens holder 3 rotates, the first and second magnetic pieces generated between the first and second magnetic pieces 11 and 12 and the first and second tracking drive magnet portions 52 and 62 are generated. Attractive force F1 ', F
2'is reduced by the same amount as compared with the case where the lens holder 3 is in the neutral state in any set, and the balance is not lost, and the first and second magnetic attraction forces F1 ',
The size of F2 'remains the same. Since the circumferential components of the first and second magnetic attraction forces F1 ′ and F2 ′ are canceled by the driving force of the tracking magnetic circuit (the force that rotates the lens holder 3 in the direction of arrow A), the lens holder 3 The first and second magnetic attraction forces F1 ′, F
The radial components F1 ″, F2 ″ of 2 ′ act. Radial components F1 ″ and F2 ″ of the first and second magnetic attraction forces F1 ′ and F2 ′ can be expressed as forces F11 ″ and F12 ″ with the axis 46 as a reference point.
11 ", F12" (first and second magnetic attraction force F
The vectors of the radial components F1 "and F2" of 1'and F2 'are equal in magnitude but deviated from the same line. Therefore, the first and second magnetic attraction forces F1 ',
The lateral pressure F'composed of the radial components F1 "and F2" of F2 'is stable with only a slight change in size and direction compared to when the lens holder 3 is in the neutral state. There is. Therefore, even when the lens holder 3 is driven, the lateral pressures F and F'are stable with only a slight change in size and direction, so that the lens holder 3 can be driven appropriately. Further, since the lateral pressure applied to the lens holder is formed by using the neutral position holding means, it is not necessary to add another mechanism.

In this example, the magnets 5 and 6 in which the focusing drive magnet portions 52 and 62 and the tracking drive magnet portions 53 and 63 are integrated are used, but they may be divided.

[Second Embodiment] In the above embodiment, the lateral pressure F
Although two sets of magnets and magnetic pieces are used to generate the above, the number of sets may be three or more, and an example of using three sets of magnets and magnetic pieces will be described below.

FIG. 5 is a plan view showing an objective lens driving device according to the second embodiment of the present invention. Since the objective lens driving device of the present example has the same basic configuration as the objective lens driving device described in the first embodiment, parts having common functions will be denoted by the same reference numerals, and description thereof will be omitted. Is omitted.

(Structure of Neutral Position Holding Means) Also in the objective lens driving device 1 shown in FIG. 5, in order to generate a magnetic force for holding the lens holder 3 at a predetermined neutral position, the outer peripheral surface of the lens holder 3 is formed. First to third magnetic pieces 11, 12 and 16 having the same specifications are adhered to each other, and these magnetic pieces 1
Reference numerals 1, 12, and 16 denote first to third magnets 52, 62, 1 having the same specifications attached to the inner peripheral surface of the outer yoke 42.
Confronts 4. Here, each of the first to third magnets 52, 62, and 14 is polarized and magnetized in the circumferential direction, and the magnetized polarization line has magnetic centers 521, 621, and
141. First to third magnets 52, 6
For 2 and 14, the tracking magnet may be used as it is for all or part of it, but it goes without saying that a magnet unrelated to the magnetic circuit for docking may be used.

Objective lens driving device 1 configured as described above
In a state in which the tracking magnetic circuit and the focusing magnetic circuit are not driven, three pairs of first to third magnetic pieces 11, 12, 16 and first to third magnets 52, 62, 14 are provided. The magnetic force generated between the magnetic piece and the magnet acts to hold the lens holder 3 at a predetermined neutral position set in advance in both the tracking direction and the focusing direction.

(Structure of Side Pressure Applying Means) In this embodiment, the magnetic pieces 11, 12 and 16 and the first to third magnets 52, 62 and 14 are used as they are to support the lens holder 3 in the holder. A lateral pressure is applied in a direction orthogonal to the axis 45. That is, in a state where the lens holder 3 is not driven, the first to third magnetic pieces 11, 12 and 16 respectively have the first to third magnets 52, 62 and 14 respectively.
Are arranged so as to face the magnetic centers 521, 621 and 141, respectively. Further, the first to third magnets 52, 62, 14 have respective magnetic centers 52.
1, 621 and 141 (magnetized polarization lines) are arranged so as to be displaced from positions at equal angular intervals around the holder support shaft 45. Therefore, in this embodiment, the first to third magnetic pieces 11, 12, 16 and the first to third magnets 5 are used.
First to third magnetic attraction forces F1, F2 and F3 having the same magnitude are generated between the magnet and the three sets of magnetic pieces 2, 62 and 14, respectively. Here, the first to third magnetic attraction forces F1, F2, F3 are all forces F11, F12, F passing through the axis 46 of the holder support shaft 45.
Can be represented as 13, and these F11, F12,
F13 (first to third magnetic attraction forces F1, F2, F
The vectors of 3) have the same magnitude but are oriented in a direction deviated from the equiangular interval. Therefore, for example, the resultant force F4 of the first and second magnetic attraction forces F1 and F2 and the third magnetic attraction force F3 have different magnitudes or directions, and therefore the first to third magnetic forces. The resultant force of the attraction forces F1, F2, F3 (the resultant force of the resultant force F4 and the third magnetic attraction force F3)
Acts as a side pressure F that presses the lens holder 3 in a direction orthogonal to the holder support shaft 45. Therefore, rattling does not occur between the holder support shaft 45 and the shaft hole 34.

Moreover, in the present embodiment, the first to third magnetic pieces 11 and 1 are provided while the lens holder 3 is not driven.
2 and 16 are first to third magnets 5 respectively
Since they are arranged so as to face the magnetic centers 521, 621 and 141 of 2, 62 and 14, respectively, when the lens holder 3 is rotated from the neutral position around the axis 46, any one of the magnetic pieces 11 , 12, 16 are also the first to third
Magnetic centers 521, 6 of the magnets 52, 62, 14 of
21 and 141 are separated by the same distance in the same rotation direction.
Therefore, when the lens holder 3 rotates, the first embodiment
In the same way as described with reference to FIG. 4, the magnetic attraction force generated between the magnet and the magnetic piece is reduced by the same amount in any pair, so that the balance is not lost.
The magnitude of the magnetic attraction remains the same in each set. Therefore, even when the lens holder is driven, the lateral pressure generated by combining the magnetic attraction forces is stable with only a slight change in size and direction. It is possible to drive the lens holder properly without rattling.

In the above embodiment, the magnetic pieces 11, 12 and 16 are attached to the lens holder 3 and the magnets 52, 62 and 14 are attached to the holder supporting member 4, however, on the contrary, the magnet 52 is attached to the lens holder 3. , 62, 14
And attach the magnetic pieces 11, 12, 1 to the holder supporting member 4.
The one with 6 attached may be used.

[0035]

As described above, in the objective lens driving device of the present invention, the lens is utilized by utilizing the magnet and the magnetic piece that generate the magnetic attraction force for holding the lens holder at the predetermined neutral position. When applying lateral pressure to the holder, instead of facing the magnetic piece at a position displaced from the magnetic center of the magnet, place the magnetic piece at the magnetic center of the magnet and place the magnet and magnetic piece at equal angular intervals. Lateral pressure is applied to the lens holder by shifting it from the position. Therefore, as long as the magnetic pieces face the magnetic center of the magnet, when the lens holder is rotated from the neutral position around the axis, both magnetic pieces have the same distance from the magnetic center of the magnet in the same rotation direction. Just leave. Therefore, when the lens holder rotates, the magnetic attraction force generated between the magnet and the magnetic piece is reduced by the same amount in any pair, so that the magnetic attraction force remains the same in each pair. Is. Therefore, even when the lens holder is driven, the lateral pressure generated by combining the magnetic attraction forces is stable because the size and direction change only slightly. It is possible to drive the lens holder properly without rattling. Further, since the lateral pressure applied to the lens holder is formed by using the neutral position holding means, it is not necessary to add another mechanism.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a portion cut along line II-II in FIG.

FIG. 3 is a perspective view showing a lens holder of the apparatus shown in FIG.

FIG. 4 is a plan view showing a state where a lens holder of the apparatus shown in FIG. 1 is driven in a tracking direction.

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

6A is a schematic plan view showing a conventional objective lens driving device, and FIG. 6B is a schematic plan view showing a state where a lens holder of the device shown in FIG. 6A is driven in a tracking direction.

[Explanation of symbols]

1 Objective Lens Driving Device 2 Objective Lens 3 Lens Holder 4 Holder Supporting Members 7, 8 Tracking Driving Coil 9, 10 Focusing Driving Coil 11, 12, 16 Magnetic Pieces 14, 52, 62 Tracking Magnets 15, 51, 61 Magnetic center of tracking magnet 45 Holder spindle F Side pressure F1, F2, F3 Magnetic attraction force

Continuation of the front page (56) Reference JP-A-2-287928 (JP, A) JP-A-8-249692 (JP, A) JP-A-63-138536 (JP, A) JP-A-63-10330 (JP , A) JP-A-6-223394 (JP, A) JP-A-7-73487 (JP, A) JP-A-5-159331 (JP, A) Actually open 2-42215 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B ^7/ 09-7/10

Claims (4)

(57) [Claims] 1. A lens holder holding an objective lens and having a shaft hole, a holder support member having a holder support shaft inserted into the shaft hole, and the lens holder mounted along the holder support shaft. A magnetic circuit driven in the axial direction and around the axial line, and in only one of the lens holder and the holder supporting member, a plurality of magnets polarized and magnetized in the circumferential direction in the magnetic circuit are paired. In an objective lens driving device having a plurality of magnetic pieces which are attached to generate a magnetic attraction force for holding the lens holder at a predetermined neutral position in a state where the magnetic circuit is not driven, The resultant force of magnetic attraction generated between the magnetic piece and the magnet forming a pair with the magnetic piece causes the holder support to the lens holder. The magnets and the magnetic pieces are arranged at positions displaced from positions at equal angular intervals to each other so as to apply a lateral pressure in a direction orthogonal to An objective lens driving device, which is arranged so as to face a magnetized polarization line. 2. The objective lens driving device according to claim 1, wherein the magnitude of the magnetic attraction force generated between the magnet and the magnetic piece is the same in any set. 3. The magnetic piece and the magnet according to claim 1, wherein two sets of the magnetic piece and the magnet are arranged so that a magnetic center of the magnet is deviated from a point-symmetrical position with the holder support shaft as a center. An objective lens driving device characterized in that 4. The magnet according to claim 3,
An objective lens driving device comprising a tracking magnet for rotating and driving the lens holder around the axis in the magnetic circuit.