JP3198236B2 - Optical pickup device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device incorporated in an optical disk device or the like. More specifically, the present invention relates to a driving device for a lens holder that holds an objective lens of an optical pickup device.

[0002]

2. Description of the Related Art As an optical pickup device incorporated in an optical disk device for reproducing an optical disk as a digital recording medium, a conventional optical pickup device is disclosed, for example, in Japanese Patent Laid-Open No. 7-11095.
No. 5 discloses this. As shown in FIG. 6,
In the optical pickup device 1, the lens holder 2 is supported by the support shaft 4 so as to be rotatable and slidable in the axial direction. A pair of focusing driving coils 6 and tracking driving coils 8 are fixed to the outer peripheral surface of the lens holder 2 at symmetrical positions with respect to the support shaft 4.

An outer yoke 10 having an arc shape centering on the support shaft 4 is formed around the lens holder 2. An arc-shaped drive magnet 12 centered on the support shaft 4 is fixed to the inner surface of the outer yoke 10. Here, a groove 12 a parallel to the support shaft 4 is formed in an intermediate portion on the inner side surface of the drive magnet 12. The groove 12a forms a focusing drive magnet 12b and a tracking drive magnet 12c.

A circular inner yoke 14 centered on the support shaft 4 is provided inside the yoke hole 2 a of the lens holder 2.
Is arranged. The inner yoke 14 is opposed to the drive magnet 12. Further, the lens holder 2
A magnetic piece 16 is fixed at a position facing the center of the focusing drive magnet portion 12b on the outer peripheral surface of the magnetic member 16a.

On the other hand, between the focusing drive magnet portion 12b and the inner yoke 14, as shown in FIG. 7,
The distribution of the magnetic flux density is formed such that the center of the focusing drive magnet portion 12b is maximized. For this reason,
When the drive coils 6 and 8 are not energized, the magnetic piece 16 is attracted to the center of the focusing drive magnet portion 12b. This state is a neutral state. When the drive coils 6 and 8 are energized in a neutral state, the lens holder 2 is rotated about the support shaft 4 to perform a tracking operation, or is slid along the support shaft 4 to perform a focusing operation. Is performed. In any case, when the energization is stopped, the magnetic piece 16 is attracted to the central portion of the focusing drive magnet portion 12b, so that the magnetic state becomes neutral.

As shown in FIG. 8 , the relationship between the frequency of the input current and the gain when rotating the lens holder 2 differs depending on the resonance frequency of the lens holder 2. Here, at frequencies exceeding the resonance frequency, the gain decreases in proportion to the input frequency. At a frequency not exceeding the resonance frequency, the gain is substantially constant regardless of the input frequency. At this time, the gain decreases as the resonance frequency increases,
The gain increases as the resonance frequency decreases. Therefore, the relationship between the input frequency and the gain at frequencies lower than the resonance frequency is
It is determined by the resonance frequency of the lens holder 2.

On the other hand, for the completed optical pickup device 1, it is required that the sensitivity of the tracking operation and the focusing operation with respect to the input current of the lens holder 2 be within a predetermined range. For this reason, in order to set the sensitivity and the gain to predetermined values, the resonance frequency of the lens holder 2 must be set in advance. Since the setting of the resonance frequency is related to the magnetic flux density acting on the magnetic piece 16, the setting is performed by changing the shape, surface area, and volume of the magnetic piece 16.

[0008]

However, in the above-described optical pickup device 1, since the resonance frequency of the lens holder 2 is set by changing the shape, surface area, and volume of the magnetic piece 16, a desired resonance frequency is obtained. It was necessary to repeat trial and error of changing the shape, surface area, and volume of the magnetic piece 16 in order to obtain. That is, it is not known how to determine the shape or the like of the magnetic piece 16 in order to set the resonance frequency to a predetermined value. Many types of magnetic pieces 16 are prepared, and the resonance frequency is measured for each of them. The one that matched the value was adopted. For this reason, the operation of setting the resonance frequency becomes extremely complicated, and much time and labor has to be spent.

Further, for example, when it is necessary to change the resonance frequency during the focusing operation, if the shape of the magnetic piece 16 is changed, the resonance frequency during the tracking operation is also changed. Conversely, when changing the resonance frequency during the tracking operation, if the shape or the like of the magnetic piece 16 is changed, the resonance frequency during the focusing operation is also changed. For this reason, the operation of setting the resonance frequency becomes more complicated.

Accordingly, it is a first object of the present invention to provide an optical pickup device capable of easily setting a resonance frequency of a lens holder. Also,
A second object of the present invention is to provide an optical pickup device in which the resonance frequencies of the focusing operation and the tracking operation can be set separately and independently.

[0011]

In order to achieve the above object, an optical pickup device according to the present invention holds an objective lens and is fixed to a lens holder movable in a tracking direction and a focusing direction. A drive coil, a drive magnet disposed opposite to the drive coil, an inner yoke disposed opposite to the drive magnet across the drive coil, and a magnet provided on the lens holder and attracted to the drive magnet by magnetic force. In the optical pickup device provided with a piece, a predetermined magnetic flux density is formed between the drive magnet and the drive magnet by projecting toward the drive magnet at a portion on the facing surface of the inner yoke facing at least the central portion of the drive magnet. modified adjusted projections so as to obtain to form a tracking direction only in a shape whose longitudinal direction,該調Forming a groove at a position corresponding to the rear side of the protrusion.

Therefore, the magnetic flux density between the drive magnet and the inner yoke is maximum at the center of the drive magnet and decreases as it approaches the end of the drive magnet.
By changing the height of the adjustment protrusion of the inner yoke, the distance between the drive magnet and the inner yoke changes, so that the distribution of the magnetic flux density is changed.

Therefore, when the height of the adjusting projection is increased, the distance between the center of the driving magnet and the inner yoke is reduced.
As a result, the maximum value of the magnetic flux density increases, and the overall shape of the magnetic flux density distribution also changes. On the other hand, when the adjustment protrusion is lowered, the distance between the center of the drive magnet and the inner yoke is increased. As a result, the maximum value of the magnetic flux density decreases, and the overall shape of the magnetic flux density distribution also changes. Here, if the relationship between the height of the adjustment protrusion and the maximum value of the magnetic flux density of the drive magnet is obtained in advance by experiments or the like, the height of the adjustment protrusion to obtain a predetermined value of the magnetic flux density can be easily calculated. can do.

[0014] Therefore, if the predetermined sensitivity is required for the lens holder of the optical pickup device is a finished product, obtains a gain for this sensitivity, resonance of the lens holder from the Bode diagram as shown in FIG. 8 Calculate the frequency. Then, the height of the adjustment protrusion is determined so that the magnetic flux density becomes the resonance frequency, and the inner yoke is formed. By using the inner yoke, a predetermined sensitivity required for the lens holder can be secured.

[0015]

[0016]

[0017]

Further, since the adjustment protrusion is formed in a shape having the longitudinal direction only in the tracking direction, when the lens holder slides in the focusing direction, the magnetic flux density depends on the position of the lens holder in the tracking direction. There is almost no change in distribution. That is, the magnetic flux density acting on the magnetic piece during the focusing operation is not affected by the tracking operation. Thus, the resonance frequency in the focusing operation can be set without being affected by the tracking operation by changing the height of the adjustment protrusion. Moreover, the resonance frequency in the tracking operation is
Even if the height of the adjustment projection is changed, it hardly changes, so that only the resonance frequency in the focusing operation can be set independently.

[0019]

[0020]

[0021]

[0022]

Furthermore, the optical pickup apparatus of claim 2, holds the objective lens, a lens holder which is movable in a tracking direction and focusing direction, and a driving coil which is fixed to the lens holder, disposed opposite to the driving coil An optical pickup device comprising: a driving magnet, an inner yoke disposed opposite to the driving magnet across the driving coil, and a magnetic piece provided on the lens holder and attracted by the driving magnet by magnetic force. At least a portion of the inner yoke facing the center portion of the magnet on the facing surface of the inner yoke is provided with an adjusting projection portion that has been changed so as to obtain a predetermined magnetic flux density with the driving magnet by projecting toward the driving magnet side. In addition, a groove is formed at a position corresponding to the back side of the adjustment protrusion, and the drive magnet is connected to the lens holder. And an arc shape along the da in the tracking direction and disposed on the outer peripheral side of the driving coil, and in the flat plate shape facing the inner yoke to the drive coil is arranged on the inner peripheral side of the driving coil, the driving magnet and the inner yoke The distance
Large end of the drive magnet at the center of the drive magnet
To reduce the magnetic flux density between the drive magnet and the inner yoke.
Degree is maximum at the center of the drive magnet,
To gradually decrease as it approaches the end of the

Accordingly, the distance between the drive magnet and the inner yoke excluding the adjustment protrusion is large at the center of the drive magnet and small at the end of the drive magnet in the tracking direction. As a result, the magnetic flux density between the drive magnet and the inner yoke reaches its maximum at the center of the drive magnet and gradually decreases as it approaches the end of the drive magnet in the tracking direction. The maximum value of the magnetic flux density can be set by providing an adjusting projection on the inner yoke.

Therefore, even if the magnetic piece moves relative to the drive magnet when the rotation angle of the lens holder or the sliding amount in the axial direction increases, the amount of change in the magnetic flux density acting on the magnetic piece from the drive magnet is small. small. Since the amount of change in the magnetic flux density is small, the amount of change in the resonance frequency of the lens holder is small. Therefore, the amount of change in gain at a frequency lower than the resonance frequency with respect to the input voltage to the drive coil is reduced.

The optical pickup device of claim 3 is
A support shaft is provided for supporting the lens holder rotatably in the tracking direction and slidably in the focusing direction. For this reason, the lens holder is rotated or slid while being supported by the support shaft.

Furthermore, the optical pickup apparatus of claim 4, the driving coil and the focusing driving coil, and the driving magnet and the focusing drive magnet.

For this reason, the magnetic flux density between the focusing drive magnet and the inner yoke reaches its maximum at the center of the focusing drive magnet and gradually decreases as it approaches the end of the focusing drive magnet.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an embodiment shown in the drawings. Prior to this,
Although not included in the embodiments of the present invention,
Optical pickup device 20 based on FIGS.
Will be explained.

[0030] As shown in FIGS. 1 to 3, the optical pickup device 20, the support shaft 25 for supporting the lens holder 24 for holding the objective lens 22, the lens holder 24
A focusing drive coil 26 and a tracking drive coil 28 fixed as drive coils fixed to the outer peripheral portion of the lens holder 24, and a focusing drive as a drive magnet disposed to face the outside of each of the drive coils 26 and 28. A magnet 30 and a tracking drive magnet 32, a focusing inner yoke 34 a positioned with the focusing drive magnet 30 sandwiching the focusing drive coil 26, and a tracking drive coil 28 together with the tracking drive magnet 32.
And an adjustment projection 34 provided on the focusing inner yoke 34a.
c and a magnetic piece 38 provided on an outer peripheral portion of the lens holder 24.
And an outer yoke 4 for fixing the respective drive magnets 30 and 32.
0a.

The lens holder 24 is supported by a support shaft 25 so as to be rotatable and slidable in the axial direction. In this example , the structure in which the lens holder 24 is supported by the support shaft 25 is used. However, a structure in which the lens holder is supported by, for example, four hinges without using the support shaft may be used. The lens holder 24 holds the objective lens 22 with the optical axis parallel to the support shaft 25. The lens holder 24 has an objective lens 2 around a support shaft 25.
A balancer 42 is fixed to the opposite side of the second. And
A pair of focusing driving coils 26 and tracking driving coils 28 are fixed to the outer peripheral surface of the lens holder 24 at symmetrical positions with respect to the support shaft 25.

The outer yoke 40a is supported by an outer yoke support plate 40b perpendicular to the support shaft 25. The outer yoke 40a and the outer yoke support plate 40b are formed of the same metal plate 40. In the center of the outer yoke support plate 40b, a through hole is provided to form a boss 40c. The support shaft 25 is fixed to the boss 40c by press-fitting, bonding, or the like. A pair of focusing drive magnets 30 and a pair of tracking drive magnets 32 are fixed to the outer yoke 40a at positions facing each other with the support shaft 25 interposed therebetween. Further, the focusing drive magnet 30 is disposed so as to face the focusing drive coil 26, and the tracking drive magnet 32 is opposed to the tracking drive coil 28.

Further, a magnetic piece 38 is attached at a position facing the center of the focusing drive magnet 30 on the outer peripheral surface of the lens holder 24. Note that this
In the example , the magnetic piece 38 is connected to the focusing drive magnet 3.
0, it may be provided at a position facing the center of the tracking drive magnet 32 as shown by the two-dot chain line in FIG. In either structure, the magnetic piece 38 is attracted to the center of the drive magnets 30 and 32 to be in a neutral state.

On the other hand, an inner yoke support plate 34g is overlaid on the outer yoke support plate 40b. Inner yoke support plate 34g
A flat-shaped inner yoke 34a for focusing facing the driving magnet 30 for focusing and a flat-shaped inner yoke 34b for tracking facing the driving magnet 32 for tracking are provided at both end portions opposed to each other with the support shaft 25 therebetween. Is provided. The inner yoke 34a for focusing, the inner yoke 34b for tracking, and the inner yoke support plate 34g are formed of the same metal plate 34. Here, the distance between each drive magnet 30, 32 and each inner yoke 34a, 34b is
The driving magnets 30 and 32 are greatly increased at the center of 0 and 32.
Is small at the side end.

Further, the inner yoke 34a for focusing
On the surface facing the focusing drive magnet 30, there is formed an adjustment protrusion 34c including a portion facing the center of the focusing drive magnet 30 and having a longitudinal direction parallel to the support shaft 25 as a longitudinal direction. A groove 34d is formed at a position corresponding to the back side of the adjusting protrusion 34c of the inner yoke 34a for focusing.

In this example , since the magnetic piece 38 is provided so as to face the focusing drive magnet 30, it is hardly affected by the magnetic flux of the tracking drive magnet 32. Therefore, from the viewpoint of setting the resonance frequency of the lens holder 24, the tracking inner yoke 34b is formed in an arc shape as in the related art, and the distance between the tracking drive magnet 32 and the tracking inner yoke 34b is fixed. It does not matter.

The inner yokes 34a, 34b pass through the yoke holes 24a formed in the lens holder 24 with a sufficient space. For this reason, the driving magnet 30 for focusing and the inner yoke 34a for focusing are used.
The focusing drive coil 26 is located between the two, and the tracking drive coil 28 is located between the tracking drive magnet 32 and the tracking inner yoke 34b.

The operation of the optical pickup device 20 will be described below.

When a current is supplied to the focusing drive coil 26, a magnetic flux is generated, and a thrust is generated between the magnetic flux and the magnetic flux generated from the focusing drive magnet 30. Thereby, the lens holder 24 slides in the axial direction of the support shaft 25, and the focusing operation is performed. In addition, when a current is applied to the tracking drive coil 28, a magnetic flux is generated,
A thrust is generated between the tracking drive magnet 32 and the magnetic flux generated from the tracking drive magnet 32. Accordingly, the lens holder 24 rotates about the support shaft 25, and the tracking operation is performed.

Here, the distance between the focusing driving magnet 30 and the focusing inner yoke 34a is large at the center of the focusing driving magnet 30.
It is reduced at the side end of the focusing drive magnet 30. In addition, the inner yoke 3 for focusing
4a, the focusing drive magnet 3 at the center of the lens holder 24 in the rotation direction is adjusted.
The distance to 0 is made small. Therefore, the magnetic piece 38
As shown by a solid line in FIG. 4, the magnetic flux density acting on the focusing drive magnet 30 becomes maximum at the center of the focusing drive magnet 30, and gradually decreases toward the side end.

Therefore, in the neutral state, the magnetic piece 38 is attracted to the focusing drive magnet 30, and is located close to the central portion where the magnetic flux density is maximum. When the tracking operation is performed, the magnetic piece 38 is shifted from the center of the focusing drive magnet 30, but the magnetic flux density applied at that position is different from the magnetic flux density applied in the neutral state. Not much different.
For this reason, the resonance frequency of the lens holder 24 that varies depending on the magnetic flux density acting on the magnetic piece 38 does not change significantly even by the tracking operation. Therefore, since the resonance frequency does not change much, the gain at a frequency lower than the resonance frequency does not change much and becomes stable. Therefore, the control of the tracking operation of the lens holder 24 is facilitated by the energization by the input voltage calculated from the gain, and the control time can be shortened.

Further, when the inner yoke 34a for focusing is formed, the distance from the drive magnet 30 for focusing is changed by changing the height of the adjusting projection 34c. Thereby, as shown by the broken line in FIG.
The distribution of the magnetic flux density in the tracking operation is changed. For example, when the adjustment protrusion 34c is raised, the distance between the central portion of the focusing drive magnet 30 and the inner yoke 34a for focusing is shortened, so that the maximum value of the magnetic flux density is increased. On the other hand, when the adjustment protrusion 34c is lowered, the distance between the center of the focusing drive magnet 30 and the inner yoke 34a for focusing is expanded, so that the maximum value of the magnetic flux density decreases. In any case, not only does the maximum value of the magnetic flux density change, but also the shape of the distribution changes.

Even when the lens holder 34 performs the focusing operation, the distribution of the magnetic flux density in the tracking operation hardly changes because the longitudinal direction of the adjustment projection 34c is parallel to the support shaft 25.

Here, if the relationship between the height of the adjusting protrusion 34c and the maximum value of the magnetic flux density of the focusing drive magnet 30 is determined in advance by experiments or the like, the adjusting protrusion for obtaining a predetermined value of the magnetic flux density can be obtained. The height of 34c can be easily calculated.

On the other hand, the configuration of the embodiment of the present invention is shown in FIGS.
In the optical pickup device 20 shown in FIG.
As described above, the adjusting projection 34c of the inner yoke 34a for focusing has a shape in which the rotation direction of the lens holder 24 is the longitudinal direction . According to this structure, the adjustment protrusion 34c
, The magnetic flux density in the focusing operation can be changed. Further, even when the lens holder 34 performs the tracking operation, the distribution of the magnetic flux density in the focusing operation hardly changes.

The above-described embodiment is a preferred embodiment of the present invention.
Although it is an example of an application, the present invention is not limited to this.
Various modifications can be made without departing from the spirit of the invention.
is there. For example, in this embodiment, the inner yaw for focusing is used.
Rotate the lens holder 24 by adjusting the adjustment projection 34c of the lens 34a.
The shape has a longitudinal direction, but this is limited to
Instead , as shown in FIG.
The adjustment projection 34c of a may be formed by a focusing projection 34e whose longitudinal direction is parallel to the support shaft 25 and a tracking projection 34f whose longitudinal direction is the rotation direction. According to this structure, by changing the height of the adjustment protrusion 34c, both the magnetic flux density in the tracking operation and the magnetic flux density in the focusing operation can be changed at the same time. Also,
The magnetic flux density in the tracking operation can be set by changing the height of the focusing direction protrusion 34e,
The magnetic flux density in the focusing operation can be set by changing the height of the tracking direction protrusion 34f.

The above-described embodiment is a preferred embodiment of the present invention.
Although it is an example of an application, the present invention is not limited to this.
Various modifications can be made without departing from the spirit of the invention.
is there. For example, in the present embodiment, the focusing drive magnet 30 and the tracking drive magnet 32 are used as the drive magnets, but these drive magnets 30 and 32 may be the same. According to this structure, a pair of drive magnets having a focusing unit and a tracking unit are provided, and a focusing drive coil and a tracking drive coil can be disposed to face each unit. And the number of parts can be reduced.

[0048]

As is apparent from the above description, in the optical pickup device according to the first aspect, the distribution of the magnetic flux density is changed by changing the height of the adjusting protrusion of the inner yoke, and the magnetic flux density can be adjusted. By obtaining the resonance frequency, a predetermined gain and sensitivity can be obtained. For this reason, the sensitivity of the lens holder of the optical pickup device can be set to a predetermined size by molding the inner yoke based on the calculated value, so that the sensitivity can be easily set without performing trial and error. Can be. This simplifies the work of setting the sensitivity, and can reduce the manufacturing time and the manufacturing cost.

[0049]

[0050] Furthermore, it independently of each other set the resonance frequency in the tracking operation of the resonant frequency in the full Okashingu operation. For this reason, the sensitivity in the focusing operation of the lens holder of the optical pickup device can be easily set.

[0051]

Further, in the optical pickup device of the second aspect , since the amount of change in the magnetic flux density acting on the magnetic piece from the drive magnet is small, the amount of change in the resonance frequency of the lens holder is small, and the amount of change in the input frequency to the drive coil is small. The amount of change in gain at frequencies lower than the resonance frequency is reduced. Thereby, when driving the lens holder, the input voltage to the drive coil is calculated based on the sensitivity in order to drive the lens holder to the target position, but if the change amount of the sensitivity is small, the calculated input voltage is accurate. And driving can be performed with high accuracy. Accordingly, control of the lens holder is facilitated, accurate positioning can be performed with a small number of drives, control time is reduced, and response speed is improved.

Further, since the drive magnet is arranged in an arc shape along the rotation direction of the lens holder and arranged on the outer peripheral side of the drive coil, the size of the optical pickup device is not increased.

Further, in the optical pickup device according to the third aspect , since the lens holder is supported by the support shaft, the rotation and sliding can be performed smoothly. Therefore, the focusing operation and the tracking operation can be performed accurately and reliably. Further, the size of the optical pickup device is not increased.

Further, in the optical pickup device according to the fourth aspect , since the driving coil is a focusing driving coil and the driving magnet is a focusing driving magnet, the magnetic piece is hardly affected by the magnetic flux of the tracking driving magnet. For this reason, the shape of the tracking drive magnet and the inner yoke opposed thereto can be made the same as the conventional shape, and the manufacturing cost does not increase.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an optical pickup device .

FIG. 2 is a longitudinal sectional view of the optical pickup device showing a state cut along a line II-II in FIG. 1;

FIG. 3 is a perspective view showing an inner yoke for focusing and an adjustment protrusion.

FIG. 4 is a graph showing a distribution of a magnetic flux density received by a magnetic piece.

FIG. 5 is a perspective view showing an inner yoke for focusing and an adjustment projection according to the present invention .

FIG. 6 is a plan view showing a conventional optical pickup device.

FIG. 7 is a graph showing a distribution of a magnetic flux density received by a magnetic piece of a conventional optical pickup device.

FIG. 8 is a Bode diagram showing a relationship between an input frequency to each drive coil and a gain.

[Explanation of symbols]

Reference Signs List 20 optical pickup device 24 lens holder 25 supporting shaft 26 focusing driving coil (driving coil) 28 tracking driving coil (driving coil) 30 focusing driving magnet (driving magnet) 32 tracking driving magnet (driving magnet) 34a inside focusing Yoke (inner yoke) 34b Inner yoke for tracking (inner yoke) 34c Adjusting protrusion 34e Focusing direction protrusion 34f Tracking direction protrusion 38 Magnetic piece

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Nobuyoshi Kinoshita 14-888 Ako, Komagane-shi, Nagano Sankyo Seiki Seisakusho Co., Ltd. Komagane Plant (56) References JP-A-62-239336 (JP, A) Kaihei 4-20618 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/09

Claims (4)

(57) [Claims] 1. A lens holder that holds an objective lens and is movable in a tracking direction and a focusing direction.
A drive coil fixed to the lens holder, a drive magnet disposed opposite to the drive coil, an inner yoke disposed opposite to the opposite side of the drive magnet across the drive coil, and In the optical pickup device provided with a magnetic piece attracted to the drive magnet by a magnetic force, in the portion on the facing surface of the inner yoke facing at least the central portion of the drive magnet,
An adjustment protrusion that is changed so as to obtain a predetermined magnetic flux density between the drive magnet and the drive magnet is formed in a shape having a longitudinal direction only in the tracking direction, and the adjustment protrusion is formed. An optical pickup device, wherein a groove is formed at a position corresponding to the back side of the portion. 2. A lens holder that holds an objective lens and is movable in a tracking direction and a focusing direction.
A drive coil fixed to the lens holder, a drive magnet disposed opposite to the drive coil, an inner yoke disposed opposite to the opposite side of the drive magnet across the drive coil, and In the optical pickup device provided with a magnetic piece attracted to the drive magnet by a magnetic force, in the portion on the facing surface of the inner yoke facing at least the central portion of the drive magnet,
An adjustment protrusion is formed so as to obtain a predetermined magnetic flux density with the drive magnet by projecting toward the drive magnet, and a groove is formed at a position corresponding to the back side of the adjustment protrusion. The drive magnet is formed in an arc shape along the tracking direction of the lens holder, is disposed on the outer peripheral side of the drive coil, and the inner yoke is formed in a flat plate shape facing the drive coil. The drive magnet and the inner
Increase the distance from the yoke at the center of the drive magnet
At the end of the drive magnet, reduce the size of the drive magnet
The magnetic flux density between the slot and the inner yoke is
At the center of the drive magnet and at the end of the drive magnet.
An optical pickup device characterized in that it gradually decreases as approaching . Wherein said claims lens holder rotatable tracking direction, and characterized in that a support shaft slidably supported in the focusing direction 1 or 2
An optical pickup device as described in the above. 4. the focusing driving coil the drive coil, an optical pickup apparatus according to claim 1, characterized in that the said driving magnet and the focusing drive magnet to claim 3.