JP2700932B2 - Compensation drive for optical pickup - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a correction driving device for an optical pickup provided in an optical memory device, a compact disk player, or the like, and in particular, without being adversely affected by secondary resonance, and The present invention relates to a correction driving device for an optical pickup capable of performing a correction driving of a lens holder without causing a loss of driving force or a play during the correction driving.

[Conventional technology]

FIG. 6 shows a correction driving device for a conventional optical pickup.

In this conventional example, a lens holder 2 holding an objective lens 1 facing an optical disc (not shown) is a leaf spring 4.
The lens holder 2 is supported by the deformation of the leaf spring 4 so that the lens holder 2 can move in the optical axis direction of the objective lens 1, that is, in the focusing correction direction (F direction). The rotating member 3 is rotatably supported by a shaft 5. By the rotating operation of the rotating member 3 about the shaft 5, a direction in which the objective lens 1 crosses the optical axis, that is, a tracking correction direction. (T direction)
It can operate to. A tracking correction mechanism (not shown) constituted by a magnet and a coil is disposed between the lens holder 2 and the fixed side, and the lens holder 2 is moved in the tracking correction direction by a driving force exerted by the driving mechanism. (T direction). Similarly, the lens holder 2 is driven in the F direction by a focusing correction mechanism composed of a magnet and a coil.

In the correction drive device shown in FIG. 7, a support shaft 9b is fixed to a support base 9a, and a sleeve 2a of a lens holder 2 holding the objective lens 1 is inserted through the support shaft 9b. The lens holder 2 is supported so as to be rotatable in the θ direction with respect to the support shaft 9b and slidably in the Y direction.
The support 9a is provided with a magnet 6, a yoke 7 for holding the magnet, and a yoke 8 facing from outside the lens holder 2. The lens holder 2 is driven in the θ direction and the Y direction by two kinds of coils (not shown) provided in the lens holder 2 and the magnetic field of the magnet 6. The distance between the objective lens 1 and the recording surface of the optical disk is corrected by the operation of the lens holder 2 in the Y direction, so that the spot of the laser beam emitted from the objective lens 1 is always focused on the recording surface ( Focusing correction). In addition, the operation of the objective lens 1 in the θ direction is corrected so that the spot of the laser beam always scans the information recording track on the recording surface of the optical disk (tracking correction).

[Problems to be solved by the invention]

However, in the conventional example in which the focusing correction drive is performed by the leaf spring 4 as shown in FIG. 6, the leaf spring 4 is deformed or curved in the tracking correction direction or another direction during the correction drive. Unnecessary elastic deformation may occur, causing subresonance. When such a sub-resonance occurs, it is difficult to perform stable servo control.

In addition, in the conventional example shown in FIG. 7, the leaf spring 4 is not used, and it is possible to suppress a sub-resonance caused by unnecessary elastic deformation of the leaf spring 4 as in the conventional example shown in FIG. become. However, in the conventional example of FIG. 7, the sleeve 2a of the lens holder 2 is inserted through the support shaft 9b as described above,
Since the focusing correction and the tracking correction are performed by sliding or rotating the lens holder 2 with respect to the support shaft 9b, sliding friction occurs between the sleeve 2a and the support shaft 9b. In this state, the lens holder 2 is driven. Therefore sleeve 2a
There is a disadvantage that the loss of the driving force increases due to the sliding resistance between the shaft and the support shaft 9b. Furthermore, since it is necessary to provide a certain clearance between the sleeve 2a and the support shaft 9b,
At the time of the correction driving, play occurs, and the dynamic characteristics are adversely affected.
Therefore, the burden at the manufacturing stage is increased, such as processing the sleeve 2a so that the clearance has a predetermined tolerance, and quality control such as whether the clearance has a predetermined tolerance is required.

The present invention has been made to solve the above-described problem, and is configured to perform the correction driving without being affected by the subresonance and without causing a loss or a play of a driving force at the time of the correction driving. It is an object of the present invention to provide a correction driving device for an optical pickup.

[Means for solving the problem]

The correction driving device of the optical pickup according to the present invention is:
A lens holder holding an objective lens facing the optical disc, a fixed-side support portion, and a rigid member interposed between the lens holder and the fixed-side support portion, wherein the rigid member, the lens holder, and the fixed side The lens holder is supported by the fixed-side support portion so as to be displaceable in the optical axis direction of the objective lens and in a direction orthogonal to the optical axis with the contact portion with the support portion as a fulcrum. A magnet constituting a magnetic drive mechanism, a coil and a yoke facing the magnet are interposed between the magnet and the yoke. One of the magnet and the yoke is provided on the lens holder and the other is provided on the fixed portion side. It is characterized in that the lens holder is urged toward the fixed-side support portion by a suction force.

(Operation)

In the above means, in the focusing correction operation, when the lens holder is driven in the optical axis direction of the objective lens, the lens holder moves in the optical axis direction with the contact portion with the rigid member as a fulcrum, and the rigid member also moves to the fixed side support portion. To the same direction. In the tracking correction operation, the lens holder rotates around the contact portion with the rigid member as a fulcrum, whereby the objective lens is driven in the tracking correction direction.
As described above, in this means, since the rigid member is used and the leaf spring is not used, the secondary resonance due to unnecessary deformation of the leaf spring does not occur. Further, since the lens holder rotates in the tracking correction direction with the contact point with the rigid member as a fulcrum, problems such as sliding resistance as in a rotation support structure using a shaft do not occur.

According to the above means, since the lens holder is pressed against the contact portion with the rigid member by the magnetic attraction between the magnet and the yoke constituting the magnetic drive mechanism, the lens holder is urged toward the rigid member. It is also possible to adopt a structure in which a separate urging member is not provided. Therefore, the number of parts can be reduced, and the assembly becomes easy.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an exploded perspective view of a correction driving device for an optical pickup according to an embodiment of the present invention, and FIG. 2 is a perspective view showing an assembled state thereof.

1 and 2 is a so-called MM (Moving Magnet) type in which a magnet is attached to a lens holder and a coil is attached to a fixed side.

In the figure, reference numeral 11 indicates a lens holder,
An objective lens 12 is held in a hole provided on a surface 11e of the lens holder 11 facing an optical disk (not shown).

The lens holder 11 is in an L-shaped state as shown in the figure. A mounting hole 11g is formed on a surface 11f of the lens holder 11 parallel to the optical axis of the objective lens 12, and a magnet 14 is fitted into the hole 11g and fixed with an adhesive or the like. Reference numeral 17 denotes a fixed-side support. A yoke 15 made of a magnetic material to which the coil 13 is attached is fixed to the fixed-side support 17. The yoke 15 may be formed integrally with the fixed-side support portion 17, or may be formed as a separate yoke.
15 may be fixed to the fixed-side support portion 17. The coil 13
Is composed of a core 13c, a focusing coil 13a wound in the horizontal direction in the figure with respect to the core 13c, and a tracking coil 13b wound in the vertical direction in the figure. The focusing coil 13a and the tracking coil 13b
The coil 13 is wound in a cross shape around the core 13c.
3 is fixed to the yoke 15 by an adhesive or the like.
If the core 13c itself is formed of a magnetic material, the core 13c
Can be used instead of the yoke 15.

Reference numeral 16 denotes a rigid plate, which includes a lens holder 11 and a fixed-side support portion 17.
Are provided in a pair in parallel at an interval in the optical axis 0-0 'direction. The rigid plate 16 is formed of, for example, a resin plate or a metal plate. A hole 16c into which the yoke 15 is inserted is formed in the center of the rigid plate 16. The rigid plate 16 is formed with three projections 16a, 16b, 16b, and the three projections 16a, 16b, 16b have an isosceles triangle formed by connecting the centers thereof, or The projections 16a are arranged so as to form an equilateral triangle, and the projection 16a that is in contact with the lens holder 11 is located at the vertex of an isosceles triangle.

The tip of the protruding portion 16a and a pair of projections 16b, as shown enlarged in FIG. 3, it is formed in a semi-spherical radius R _1. Further, a concave spherical surface 11b is formed at a contact portion of the lens holder 11 with each of the protrusions 16a. This concave sphere 1
Radius of 1b is R _2. The radius R ₂ is greater than the radius R ₁ of the protrusion 16a. In this contact portion, for example, the third
In the figure, when the lens holder 11 moves up or down, the lens holder 11 is displaced by the rolling of the concave spherical surface 11b and the projection 16a of the rigid plate 16. The other protrusion 16b of the pair of rigid plates 16
Also the projection 16a and a hemispherical surface of radius R ₁ as well. The fixed-side supporting portion 17, the concave spherical surface 17c of the radius R ₂ is formed at four locations, a total of four projections 16b of the two rigid plates 16 so that it can roll on the concave spherical surface 17c In contact.

Two contact portions between the concave spherical surface 11b and the protrusion 16a on the lens holder 11 side are arranged along the optical axis direction of the objective lens. Therefore, the rolling of the concave spherical surface 11b and the projection 16a and the rolling of the concave spherical surface 17c and the projection 16b can not only displace the lens holder 11 in the focusing correction direction (F direction), but also
Due to the rolling of the concave spherical surface 11b and the projection 16a, a rotational displacement can be made in the tracking correction direction with 0a as _a fulcrum.

In the embodiment shown in FIG. 3, the projections 16a and 16b are formed integrally with the rigid plate 16, but as shown in FIG. May be embedded to form a projection on the spherical surface. Further, when the lens holder 16 is made of resin, as shown in FIG.
May be coated with a low friction layer 21 such as a fluororesin to reinforce the hardness of the surface of the concave spherical surface 11b and reduce the coefficient of rolling friction between the rigid plate 16 and the projection 16a. The sphere 16d is the other protrusion 1 of the rigid plate 16.
6b, and the low friction layer 21 can also be applied to the concave spherical surface 17c on the fixed-side support portion 17 side.

In the assembled state shown in FIG. 2, the projection 16a is
The protrusion 16b is in contact with the concave spherical surface 17c of the fixed-side support portion 17 in contact with the first concave spherical surface 11b.

In the present embodiment, the correction driving device is formed of the MM type, and the magnet 14 and the yoke 15 or the (core 13c) are attracted in a direction approaching each other. The side support portions 17 are attracted in a direction approaching each other.

 Next, the operation will be described.

In the focusing correction operation, the focusing coil
The current supplied to 13a is controlled. In the focusing coil 13a, the driving force exerted by the current flowing in the horizontal direction in FIG.
The lens holder 11 is finely driven in the F direction. In the focusing correction operation of the lens holder 11, a pair of rigid plates
The lens holder 11 is displaced, and the lens holder 11 moves in parallel with the fixed support 17 in the F direction. At this time, the projections 16a and 16b
Of the lens holder 11 and the concave spherical surface 17c of the fixed-side support portion 17 roll.
By this focusing correction operation, correction is performed so that the spot of the laser beam emitted from the objective lens 12 always matches the recording surface of the optical disc.

As described above, the distal ends of the protrusions 16a and 16b of the rigid plate 16 have the concave spherical surfaces of the lens holder 11 and the fixed-side support 17 respectively.
Since the focusing correction is performed by moving the rolling members 11b and 17c, unnecessary elastic deformation of the supporting member of the lens holder does not occur, and no sub resonance occurs.

In the tracking correction operation, the tracking coil
The current supplied to 13b is controlled. In the tracking coil 13b, a driving force (moment) in the T direction is given to the lens holder 11 by a driving force exerted by a current flowing vertically in FIG. 2 and a magnetic field of the magnet 14. By the concave spherical surface 11b of this time the lens holder 11 rolls with respect to the distal end of the projection 16a of the rigid plate 16, T about the center 0 _a (see FIG. 3) of the hemispherical surface of the projection 16a
Rotate in the direction. With this correction operation, the spot of the laser beam emitted from the objective lens 12 is corrected so as to scan the information recording track of the optical disk.

As described above, the projection 16a of each rigid plate 16 abuts against the concave spherical surface 11b of the lens holder 11, and the rolling operation of the abutting portion causes the lens holder 11 to be corrected and driven not only in the focusing direction but also in the tracking direction. Become so.
As described above, since the lens holder 11 is driven for tracking with the contact portion with the rigid plate 16 as a fulcrum, the tracking correction operation is performed by rotating and sliding about the support shaft as in the conventional example shown in FIG. Such a problem of sliding friction and a problem of backlash of the sliding portion do not occur.

In the present embodiment, there is no need to dispose coils and yokes on both sides of the lens holder 11 as in the related art, and the size of the apparatus can be reduced. In addition, since the coil and the magnet can each be configured as a single unit, the size and weight can be reduced.

It should be noted that, contrary to the above embodiment, a magnet may be provided on the fixing portion side and the yoke and the coil may be fixed on the lens holder side.

Furthermore, in the above embodiment, the rigid plate 16 and the fixed support portion 17 come into contact with each other, whereby the rigid plate 16 can be displaced up and down. However, the rigid plate 16 is formed of a resin such as an elastomer, A hinge having a small cross section may be formed in the plate 16 so that the rigid plate 16 and the fixed-side support portion 17 are connected by the hinge, and the rigid plate 16 can be vertically displaced by the hinge. That is, only the rigid plate 16 and the lens holder 11 may be brought into contact with the projection 16a and the concave spherical surface 11b.

〔effect〕

As described above, according to the present invention, since the configuration is as described above, the following effects can be obtained.

(1) Unnecessary elastic deformation of the support member of the lens holder does not occur, and the occurrence of sub-resonance can be suppressed. Therefore, stable servo control can be performed.

(2) The lens holder is driven for correction by the rolling movement, and the loss at the time of correction driving is very small.

(3) The play generated during the correction driving is suppressed.

(4) Since the rigid member is press-contacted and interposed between the lens holder and the fixed-side support portion, there is no direct contact portion, and the assembling time is shortened.

(5) Since the lens holder and the fixed-side support are attracted to each other by the attraction force of the magnet and the yoke for obtaining the driving force at the time of correction driving, a pulling spring for attracting the lens holder and the fixed-side support. Becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a correction driving device for an optical pickup according to the present invention, FIG. 2 is a perspective view showing an assembled state thereof, and FIG.
FIG. 4 is an enlarged sectional view showing a contact portion between a lens holder and a rigid plate. FIGS. 4 and 5 are sectional views of a projection and a concave spherical surface for explaining another embodiment of the present invention. Seventh
FIG. 1 is a perspective view showing a correction driving device of a conventional optical pickup. 11 ... Lens holder, 12 ... Objective lens, 13 ... Coil, 14 ... Magnet, 16 ... Rigid plate, 16a, 16b ... Protrusion, 17 ... Fixed side support, 11b, 17c ... Concave Spherical surface.

Claims (1)

(57) [Claims] A lens holder for holding an objective lens facing the optical disk, a fixed-side support portion, and a rigid member interposed between the lens holder and the fixed-side support portion;
The lens holder is displaceably supported in the optical axis direction of the objective lens and in a direction perpendicular to the optical axis with respect to the fixed side support with the contact portion between the rigid member and the lens holder and the fixed side support as a fulcrum. , A magnet constituting a magnetic drive mechanism, a coil and a yoke opposed thereto are interposed between the fixed-side support portion and the lens holder,
An optical pickup characterized in that one of a magnet and a yoke is provided on a lens holder and the other is provided on a fixed portion side, and the lens holder is urged to a fixed side support portion by magnetic attraction between the magnet and the yoke. Correction drive.