JP3330516B2 - 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 disk such as a CD or a DVD. More specifically, the present invention relates to a side pressure applying technique for removing a tilt and rattling of a lens holder in a shaft sliding type objective lens driving device.

[0002]

2. Description of the Related Art For example, Japanese Patent Publication No. 7-5251 discloses an objective lens driving device for an optical pickup such as a CD or DVD.
The shaft sliding type disclosed in Japanese Patent Application Publication No. 4 (KOKAI) No. 4 is known. An objective lens driving device of this type includes a lens holder holding an objective lens, a holder support member having a holder support shaft movably supporting the lens holder in a focusing direction and a tracking direction, and a holder support shaft. And a holder driving magnetic circuit for moving along.

In this type of objective lens driving device of the shaft sliding type, rattling tends to occur between the holder support shaft and the shaft hole, and if there is such rattling, the holder support is attached to the inner peripheral surface of the shaft hole. The shaft is one-sided. In this case, the lens holder may not be able to slide and rotate smoothly. In addition, if such rattling occurs, double resonance may occur in the lens holder, and proper driving thereof may be hindered. Further, the lens holder may be tilted with respect to the holder support shaft due to the backlash, that is, the objective lens may be tilted, and the optical performance of the optical pickup may be deteriorated.

Therefore, conventionally, for example, as shown in FIG. 5A, magnetic pieces 21 and 22 attached to the outer peripheral surface of the lens holder 3 and these magnetic pieces 21 and 2
In the magnets 9 and 10 facing the magnetic piece 2, the magnetic piece 2
The magnetic attractive forces generated between the magnetic pieces 21 and 22 and the magnets 9 and 10 by making the sizes of the magnetic pieces 1 and 22 or the distances L2 and L3 between the magnetic pieces 21 and 22 and the magnets 9 and 10 different. The resultant force of F1 and F2 acts on the lens holder 3 as a lateral pressure F in a direction orthogonal to the holder support shaft 42.

[0005]

However, as in the prior art, the magnetic attraction force F1, which is generated between the magnetic pieces 21, 22 on the outer peripheral surface of the lens holder 3 and the magnets 9, 10, as in the prior art.
In the configuration using the resultant force of F2 as the lateral pressure F, there is a problem that a constant lateral pressure F cannot be obtained. That is, when the lens holder 3 rotates around the holder support shaft 42, the magnetic pieces 21, 22 and the magnets 9, 10 move away from each other as shown in FIG.
Magnetic attraction forces F1 ′ and F2 ′ generated between the magnet 22 and the magnets 9 and 10 decrease, and the lateral pressure F also decreases.

Further, the present applicant has previously filed Japanese Patent Application No. 8-71.
No. 582, as shown in FIG. 6 (a), a pair of magnets 9 and 10 located at point-symmetric positions with respect to the holder support shaft 42 are reciprocated from a point-symmetric position with respect to the holder support shaft 42. A pair of magnetic pieces 21 at positions shifted in the opposite direction to
22 and the magnetic pieces 21 and 22 and the magnets 9 and 10
And a resultant force of the magnetic attractive forces F3 and F4 generated between the lens holder 3 and the lens holder 3 acts as a lateral pressure F in a direction orthogonal to the holder support shaft 42. However, in this configuration, as shown in FIG. 6B, the magnets 9 and 10 and the magnetic pieces 2
Magnetic attraction force F3 ', F4' generated between the first and second magnetic heads 1, 22
And the magnitude and direction of the lateral pressure F fluctuate.

[0007] In view of the above problems, an object of the present invention is to provide:
In an objective lens driving device that supports a lens holder holding an objective lens so as to be rotatable in a tracking direction and movable in a focusing direction by a holder support shaft, a constant lateral pressure is applied even when the lens holder rotates around the holder support shaft. Another object of the present invention is to provide a configuration that can be given to

[0008]

In order to solve the above-mentioned problems, the present invention provides a lens holder holding an objective lens, and a holder supporting the lens holder so as to be rotatable in a tracking direction and movable in a focusing direction. In an objective lens driving device having a support shaft and side pressure applying means for applying a side pressure to the lens holder in a direction orthogonal to the holder support shaft, in the side pressure applying means , one of a magnetic part and a magnet is provided. A first member is formed on the holder support shaft side, and the lens holder includes:
The other of the magnetic part and the magnet is a second member.
To be disposed at a position facing the first member.
Multiple holes are provided at different angular positions when viewed from the holder spindle
At least one of the plurality of storage holes.
The second member is housed in the storage hole .

For example, the magnetic portion is formed as the first member on the holder support shaft side, and the magnet is formed as the second member on the lens holder side.
Conversely, the magnetic portion may be formed on the lens holder side as the second member, and the magnet may be formed on the holder support shaft side as the first member.

With the former configuration, a magnetic attraction force is generated between the magnetic portion (first member) formed on the holder support shaft side and the magnet (second member) formed on the lens holder side. Therefore, the portion of the lens holder where the magnet is formed is drawn to the holder support shaft. Therefore, since the lateral pressure is applied to the lens holder in a direction perpendicular to the holder support shaft, the inclination and rattling of the lens holder can be suppressed. Also, even if the lens holder rotates about the holder spindle, the distance between the magnet and the magnetic part formed on the holder spindle does not change, so the magnitude of the magnetic attractive force generated between the magnet and the magnetic part That is, the magnitude of the lateral pressure acting on the lens holder does not change. Furthermore, since the magnetic attraction force generated directly between the lens holder and the holder support shaft is used as the side pressure, the direction of the side pressure when viewed from the lens holder even when the lens holder rotates around the holder support shaft. Are the same. Furthermore, in the present invention
The holder is provided in the lens holder.
A plurality is formed in advance around the support shaft, and a plurality of these are stored.
A second member is housed in at least one of the holes. You
In other words, lateral pressure is generated in the optimal direction among multiple storage holes
The second member is attached to the storage hole
Therefore, according to the present invention, the lateral pressure is applied from the optimal direction.
be able to.

Such an operation and effect can be achieved by the latter configuration (the magnetic portion is formed as the second member on the lens holder side, and the magnet is formed on the holder support shaft side as the first member). Configuration) can be similarly obtained.

[0012] In the present invention, the magnetic portion may be the first part.
When the member is formed on the side of the holder support shaft,
The holder support itself may be formed of a magnetic material as the first member. With such a configuration, since the entire holder support shaft is a magnetic portion, even if the magnet is disposed as the second member at any position around the holder support shaft in the lens holder, the magnet in the direction corresponding to the position of the magnet is disposed. Lateral pressure can be obtained. In addition, since the entire holder support shaft is a magnetic portion, it is easy to configure so that the direction of the side pressure is the same as viewed from the lens holder even when the lens holder rotates about the holder support shaft. Also, compared with the case where the holder support shaft is constituted by the magnet as the first member, there is no need to impart slidability to the magnet, and so on.
A simple configuration is sufficient.

In the present invention, it is preferable that the second member is formed in a housing hole of the lens holder so as to extend along an axial direction of the holder support shaft. That is,
The plurality of storage holes extend along an axial direction of the holder support shaft.
Extending so as to face the holder support shaft.
And the second member is provided with the holder support shaft in the storage hole.
It is preferable to face. In such a configuration, since the second member on the lens holder side is in a state of facing the entirety of the holder support shaft in the axial direction, the first member is provided substantially entirely in the axial direction of the holder support shaft. Is configured, a uniform side pressure acts in the thickness direction of the lens holder, and a large side pressure can be obtained because the facing area between the first member and the second member is large. Therefore, the inclination and rattling of the lens holder can be suppressed more reliably. Also,
Even when the lens holder moves in the axial direction of the holder support shaft, the second member can always be configured to face the first member of the holder support shaft, so that the lens holder moves in the axial direction of the holder support shaft. A stable lateral pressure can be obtained even when it is performed.

In the present invention, in the lens holder side,
Wherein the second member is disposed among the plurality of storage holes.
One of the storage holes that are not filled with elastic material
Is preferred. With this configuration, the second part
The elastic material attached to the storage hole where the material is not placed is
Functions as a damper to absorb the vibration of the lens holder
You.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the objective lens driving device according to the present invention will be described below with reference to the drawings.

(Basic Configuration) FIG. 1 is a plan view of an objective lens driving device according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.

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

The lens holder 3 has a cylindrical body part whose upper end is closed by the top plate 30, and a cylindrical bearing part formed at the center of the body part. A holder support shaft 42 is provided inside the bearing part. The shaft hole 42 is inserted. The objective lens 2 is mounted on the upper surface of the top plate 30.

A tracking magnetic circuit for rotating the lens holder 3 around the axis of the holder support shaft 42 between the lens holder 3 and the holder support member 4, and an axial direction of the lens holder 3 along the holder support shaft 42. Is formed. The tracking magnetic circuit and the focusing magnetic circuit include a pair of tracking drive coils 5 and 6 mounted on the outer peripheral surface of the lens holder 3 and a pair of focusing drive coils 7 and 8.
And an outer yoke 4 facing the drive coils.
The first and second magnets 9 and 13 are attached to the inner peripheral surface of the third magnet 3.

The first and second tracking drive coils 5 and 6 have a flat shape with a substantially rectangular longitudinal section, and one end surface thereof is adhered to the outer peripheral surface of the lens holder 3. First and second focusing drive coils 7,
Reference numeral 8 extends in the direction of the axis of the holder support shaft 42 with a substantially rectangular cross section, and its outer peripheral surface is bonded to the outer peripheral surface of the lens holder 3. Focusing drive coil 7,
Reference numeral 8 denotes an air core coil, and the inner yokes 44 and 45 are located in the air core portion.

The first and second magnets 9 and 13 are circumferentially polarized around a portion where the tracking drive coils 5 and 6 face each other.
The vicinity of 14 is the first and second tracking drive magnet units 11 and 15. The first and second magnets 9 and 13 are provided with focusing drive coils 7 and 8.
Are opposed to each other and are magnetized into a single pole, which constitutes first and second focusing drive magnet portions 12 and 16. Therefore, by controlling the power supply to each of the drive coils 5, 6, 7, 8 via the FPC board 24, the lens holder 3 is moved in the tracking direction (rotation around the axis of the holder support shaft 42) and in the focusing direction. (Movement in the axial direction along the holder support shaft 42). The first and second magnets 9 and 13 may be formed by attaching two magnets of different magnetic poles, which are magnetized in a single direction without being polarized.

(Structure of Lateral Pressure Applying Means) In this embodiment, as described below, one of the magnetic portion and the magnet is formed as a first member on the holder support shaft 42 side.
By forming the other member as a second member at a position facing the first member on the lens holder 3 side, a side pressure applying means for applying a side pressure to the lens holder 3 in a direction orthogonal to the holder support shaft 42 is provided. It is configured.

In the present embodiment, first, the holder support shaft 42 is entirely formed of a magnetic material, and itself serves as the magnetic portion (first member). On the other hand, the lens holder 3 is a resin molded product such as polyphenylene sulfide, and near the shaft hole 32 on the side opposite to the objective lens mounting portion 31 with the shaft hole 32 interposed therebetween. A magnet housing hole 33 penetrating in the axial direction is formed.

The magnet storage hole 33 has a rectangular cross section and a vertical cross section, and a rectangular parallelepiped rod-shaped magnet 17 (second member) is fixed therein by a method such as press-fitting or bonding. . The length dimension of the magnet 17 in the direction along the holder support shaft 42 is the lens holder 3.
The thickness of the magnet 17 in the direction along the holder support shaft 42 is set to be substantially the same, and the entire magnet 17 in the axial direction faces the holder support shaft 42 in parallel.

The objective lens driving device 1 thus configured
In the side pressure applying means, a magnetic attractive force indicated by an arrow F is generated between the side of the holder support shaft 42 formed as a magnetic part and the magnet 17 disposed on the side of the lens holder 3, so that the magnet of the lens holder 3 The portion where 17 is arranged is drawn to holder support shaft 42. Therefore, the lateral pressure F is applied to the lens holder 3 in a direction orthogonal to the holder support shaft 42.
, The inclination and rattling of the lens holder 3 can be suppressed. Further, even if the lens holder 3 rotates about the holder support shaft 42, the distance L1 between the magnet 17 and the holder support shaft 42 does not change, so that the magnetic attraction force generated between the magnet 17 and the holder support shaft 42. That is, the lateral pressure F acting on the lens holder 3
The size of does not change. Furthermore, since the magnetic attraction force generated directly between the lens holder 3 and the holder support shaft 42 is directly used as the lateral pressure F, the lens holder 3
Is rotated about the holder support shaft 42, the direction of the lateral pressure F is the same as viewed from the lens holder 3. That is, even if the lens holder 3 rotates about the holder support shaft 42, the direction of the side pressure acting on the lens holder 3 is always constant while the portion where the magnet 17 is arranged is drawn toward the holder support shaft 42. In addition, since the size of the lens holder 3 is constant, the lens holder 3 is properly driven in a stable state even during tracking driving, and does not tilt.

In this embodiment, since the magnet 17 extends in parallel to the holder support shaft 42 by the same length as the thickness of the lens holder 3, a large side pressure F can be obtained because the facing area is large. Furthermore, since the magnet 17 of the lens holder 3 is in a state of facing substantially the entire axial direction of the holder support shaft 42, a uniform lateral pressure F acts in the thickness direction of the lens holder 3. Therefore, the inclination and rattling of the lens holder 3 can be suppressed more reliably. In addition, the lens holder 3 is attached to the holder support shaft 42 during focusing driving.
Since the magnet 17 of the lens holder 3 always faces the holder support shaft 42 even when the magnet 17 moves in the axial direction, the lateral pressure F can be applied stably. Therefore, the lens holder 3 does not tilt during focusing driving.

Further, the magnet 17 has a shaft hole 32.
Is mounted on the side opposite to the objective lens mounting portion 31 with the interposition therebetween, so that the weight of the side of the objective lens 3 and the side of the magnet 17 around the shaft hole 3 can be balanced. Therefore, there is also an advantage that the magnet 17 can be used as a balancer.

In this embodiment, a magnet housing hole 33 is formed in the lens holder 3 in advance, and the magnet 1 is inserted there.
Although the configuration is such that the lens 7 is mounted, a configuration in which insert molding is performed at the time of molding the lens holder 3 and the magnet 17 is embedded in the lens holder 3 may be employed.

FIG. 3 (feature of this form), Renzuhoru objective lens driving apparatus 1 shown in FIG. 1
It is a top view which shows the characteristic part of da3.

In FIG . 3, the lens holder 3 has a shaft hole 3
Four magnet storage holes 33 ~ at equal angular intervals around 2
36 are formed in advance. Here, the four magnet storage holes 33 to 36 may have the same shape or different shapes, but in any case, the magnet 17 manufactured by mass production is connected to the magnet storage holes 33 to 36. Attach to any of That is, the direction of the lateral pressure F is set to an optimal condition depending on which of the magnet housing holes 33 to 36 is to be fitted with the magnet 17.

For example, as shown in a sectional view of the lens holder in FIG. 4, when the shaft hole 32 of the lens holder 3 is formed in a V shape, two holes at both ends of the inner peripheral surface of the shaft hole 32 are formed.
The magnet 17 is attached to, for example, the magnet storage hole 35 of the magnet storage holes 33 to 36 so that the portion contacts the holder support shaft 42. As described above, it is possible to select from which direction the lateral pressure F should be applied to the lens holder 3 according to the molding state of the lens holder 3.

An elastic material such as rubber is inserted into the magnet housing holes 33, 34, and 36 in which the magnet 17 is not inserted, and a composite structure of the elastic material and the synthetic resin is used to make them a lens. It may be used as a damper for absorbing the vibration of the holder 3.

Forming the entire holder support shaft 42 of a magnetic material has the advantages that the lens holder 3 can be effectively prevented from tilting and rattling and is easy to manufacture. The magnetic portion may be formed only in the portion facing 17.

Further, in the above-described embodiment, there is no need to impart slidability to the magnet 42 as compared with the case where the holder support shaft 42 is constituted by a magnet. Is formed of a magnetic material, and the magnet 17 is formed on the lens holder 3 side. On the contrary, the holder support shaft 42 is formed by a magnet, or the magnet portion is formed on the holder support shaft 42 while the lens 17 is formed. Even when a magnetic body facing the magnet portion is formed on the holder 3 side, a stable lateral pressure can be obtained. In this case, in the lens holder 3 shown in FIG. 1 or FIG. 3, a magnetic material storage hole is formed in place of the magnet insertion holes 33, 34 to 36, and a rod-shaped magnetic material is mounted in place of the magnet 17. Good.

[0035]

As described above, the objective lens driving device according to the present invention utilizes the magnetic attraction generated between the magnet and the magnetic portion formed on the holder support shaft and the lens holder as a side pressure, and uses the lens as a side pressure. Hold down the tilt and backlash of the holder. Therefore, even when the lens holder rotates about the holder support shaft, the distance between the magnet and the magnetic portion does not change, and the magnitude of the lateral pressure acting on the lens holder does not change. Further, since the magnetic attraction force generated directly between the lens holder and the holder support shaft is used as the side pressure, the direction of the side pressure is the same as viewed from the lens holder even when the lens holder rotates around the holder support shaft. It is.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view taken along a line II-II in FIG.

FIG. 3 is a plan view showing a characteristic portion of a lens holder to which the present invention is applied .

FIG. 4 is a cross-sectional view of a portion taken along line IV-IV in FIG.

FIGS. 5A and 5B are plan views schematically showing a conventional objective lens driving device.

6A and 6B are plan views schematically showing a conventional objective lens driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens drive device 2 Objective lens 3 Lens holder 4 Holder support member 5, 6 Tracking drive coil 7, 8 Focusing drive coil 9, 13 Drive magnet 17 Magnet 32 Shaft hole 33, 34, 35, 36 Magnet accommodation hole 42 Holder spindle F side pressure

Claims (5)

(57) [Claims] A lens holder holding an objective lens;
A holder spindle supporting the lens holder rotatably in the tracking direction and movable in the focusing direction,
In an objective lens driving device having a side pressure applying unit for applying a side pressure to the lens holder in a direction orthogonal to the holder support shaft, in the side pressure applying unit , one of a magnetic part and a magnet is a first member. Formed on the side of the holder spindle
The lens holder has a magnetic part and a magnet.
The other of the members as a second member and corresponding to the first member.
Is the storage hole to be placed at the facing position
From the viewpoint of different angles,
The second member is inserted into at least one of the storage holes
An objective lens driving device which is housed . 2. The objective lens driving device according to claim 1, wherein the magnetic portion is formed as the first member on a side of the holder support shaft. 3. The method according to claim 2, wherein:
An objective lens driving device, wherein the first member itself is formed of a magnetic material as the first member. 4. The method according to claim 1, wherein
The plurality of storage holes extend along an axial direction of the holder support shaft.
Extending so as to face the holder support shaft.
And the second member is provided with the holder support shaft in the storage hole.
An objective lens driving device characterized by being opposed to the above . 5. The method according to claim 1, wherein
On the lens holder side, of the plurality of storage holes,
In any of the storage holes where the second member is not arranged,
An objective lens driving device containing an elastic material .