JPH0652562A - Driving device for objective lens - Google Patents

Abstract

PURPOSE:To provide an objective lens driving device which has a relatively simple structure and can be manufactured with high workability and, at the same time, which is provided with a tilt correcting mechanism which can evade such an unstable constitution that causes resonance against vibrations. CONSTITUTION:The driving device is provided with a means which fixes a magnetic yoke 26 to an actuator pedestal 30 by deforming the fitting section 31 of the yoke 26 is provided and is constituted so that tilt correction can be performed to make the optical axis 25 of an objective lens coincident with the optical axis 24 of laser light by deforming the section 31. Therefore, the tilt correction is performed by pulling and tilting the whole body of the yoke 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the optical recording of information,
The present invention relates to an objective lens driving device for an information recording device head for reproducing or erasing.

[0002]

2. Description of the Related Art FIG. 11 shows a conventional objective lens driving device constructed as shown in FIG. Here, the objective lens 1 is held by the lens holder 2. A focus driving coil 3 is wound around the outer circumference of the lens holder 2, and a plurality of tracking driving coils 4 (here, four) are fixed to the outer circumference thereof. The lens holder 2 is supported by an elastic member, for example, a leaf spring 5 so as to be movable in the vertical and horizontal focus directions and the tracking direction orthogonal to each other. This leaf spring 5 has a leaf spring mounting member 6 at one end.
Is stuck to. The magnetic circuit comprises a magnetic yoke 7 and a magnet 10, and the magnetic yoke 7 is provided with an outer yoke 8 and an inner yoke 9 to which the magnet 10 is fixed. Then, by controlling the current in the coil in the magnetic field generated in the gap between the magnet 10 and the inner yoke 9, the objective lens 1 is driven in the focus direction and the tracking direction. The leaf spring mounting member 6 is fixed to the outer yoke 8.

Further, as shown in FIG. 12, the objective lens driving device employs a tilt correction mechanism for aligning the optical axis of the objective lens with the optical axis of the laser light.
That is, the lower portion of the magnetic yoke 7 is convex and is formed into a substantially spherical surface 11 on the outside. Correspondingly to this, the base 12 side is concave, and the inside is almost spherical surface 13
(Or conical surface). As a result, the magnetic yoke 7 is movable in the direction of tilting along the spherical surface 13. This inclination adjustment is performed by loosely fitting the holes 14 and 15 provided on the base 12 (cross section) to the screw hole 1 provided on the magnetic yoke 7.
This is performed by threadably adjusting screw rods (screw rods) 18 and 19 to 6 and 17, respectively.

In this case, the hole 20 provided in the magnetic yoke 7
The threaded rod 22 is loosely fitted in the base 22, and the threaded rod 22 is further attached to the base 12
The coil spring 23 is provided between the threaded rod 22 and the magnetic yoke 7 while being screwed into the screw hole 21 provided in the
In this portion, the magnetic yoke 7 is always subjected to downward biasing force in FIG. As a result, even if the screw rods 18 and 19 are adjusted, the magnetic yoke 7 and the base 12 are inclined while maintaining a close contact state. In this way, in the conventional objective lens driving device, the optical axis 24 of the laser beam emitted from the optical head and the optical axis 25 of the objective lens 1 are aligned.

[0005]

However, in this method, the lower portion of the magnetic yoke 7 is convex and the outer spherical surface 11 is formed, and the base 12 is concave, and the inner spherical surface 13 ( Or conical surface) molding is required. Even if a relatively simple cutting process is adopted for this molding, the high cost cannot be avoided. In addition, since the magnetic yoke 7 is biased by the coil spring, the base 12, which is a movable member, vibrates at a high speed due to a seek operation or the like, and the objective lens 1 vibrates when performing a focusing operation or a tracking operation. However, resonance may occur, which adversely affects focus control, tracking control, and seek control.

When no current is applied to the focus driving coil 3, the lens holder 2 is under its own weight at a position where the leaf spring 5 is not bent, for example, near the lowest point of the control range. , And further down there,
The leaf spring 5 will continue to be distorted. However, in terms of design, it is desirable to perform the focusing operation and the tracking operation in a state where the leaf spring 5 is not initially bent, and so-called bias current is applied to raise the lens holder 2 to the design origin. I have to continue. This puts a heavy burden on electrical control.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a structure that is relatively simple and has good workability, and avoids an unstable structure against vibration that causes resonance in a driving state. The present invention aims to provide an objective lens driving device including the tilt correction mechanism.

Another object of the present invention is to provide an objective lens driving device capable of holding a lens holder at a neutral position (origin) in the range of focus drive control without applying a bias current. It is a thing.

[0009]

In order to solve the above-mentioned problems, an objective lens driving device according to the present invention mounts an objective lens for converging laser light on a recording / reproducing surface of a recording medium in a lens holder, and an actuator. The lens holder is supported on the base in a movable state with respect to the focus direction of the objective lens and the tracking direction orthogonal to this direction, and the objective lens is driven in the focus direction and the tracking direction. In an objective lens driving device in which a coil and a tracking coil are mounted on a lens holder, and a magnetic circuit including a magnetic yoke and a magnet is mounted on the actuator base side, the magnetic yoke of the magnetic yoke is attached to the actuator base. It is equipped with a means for fixing by deforming the mounting part, Wherein a variation of the mounting portion, and constitutes the optical axis of the objective lens to perform tilt correction to match the optical axis of the laser light when the.

In the objective lens driving device having the above structure, however, a part of the magnetic yoke is deformed so that the entire magnetic yoke is pulled and tilted, whereby tilt correction is performed.

Further, the lens holder is provided with a supporting portion for the objective lens, and by deforming the supporting portion, tilt correction for making the optical axis of the objective lens coincide with the optical axis of the laser light is performed. Is configured to do.

Further, the lens holder is provided with a supporting portion for the objective lens, and an adhesive, an adhesive member or a spacer having a required thickness is interposed between the supporting portion and the objective lens. Thereby, tilt correction is performed so that the optical axis of the objective lens coincides with the optical axis of the laser light.

Further, the lens holder is equipped with a float in which a gas having a specific gravity smaller than that of air is enclosed in order to hold itself at the neutral position in the focus direction. It is possible to reduce the burden of electric control such as applying a bias current for

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. Here, as in the conventional example, the objective lens 1 is held by the lens holder 2. A focus driving coil 3 is wound around the outer circumference of the lens holder 2, and a plurality of tracking driving coils 4 (four in this embodiment) are wound around the outer circumference.
It is fixed. The lens holder 2 is supported by an elastic member, for example, a leaf spring 5 so as to be movable in the vertical and horizontal focus directions and the tracking direction orthogonal to each other. One end of the leaf spring 5 is fixed to the leaf spring mounting member 6. The magnetic circuit includes a magnetic yoke 26 and a magnet 27. An outer yoke 28 and an inner yoke 29 to which the magnet 27 is fixed are attached to the magnetic yoke 26, and a gap is formed between the magnet 27 and the inner yoke 29. The objective lens 1 can be driven in the focus direction and the tracking direction by controlling the current in the coil within the magnetic field generated in the air gap. The leaf spring mounting member 6 is fixed to the outer yoke 28.

The magnetic yoke 26 is provided with bent portions 31, 32, and 33 in the lower portion of its outer periphery in the vicinity of the base 30 so as to form a tilt correction mechanism. As shown in the drawing, the bent portions 31, 32, 33 are mounting portions of a plurality of magnetic yokes (for example, three),
It is bent toward the base 30 via the bent portions 34, 35, 36. Further, folding portions 37, 38, 39 are provided at the portion contacting the base 30,
When the tilt of the magnetic yoke 26 is adjusted by the bending of the bent portions 31, 32, 33, the magnetic yoke 26 slides on the base 30, and the same portion is caught on the upper portion of the base 30 and tilt adjustment becomes impossible. Is preventing.

This tilt adjustment is performed by bending portions 34, 35,
The screw rods (screw rods) 43, 44, 45 are loosely fitted in the holes 40 (41, 42 not shown) provided in the base 36, and the base 30
This is achieved by adjustingly screwing into a screw hole (not shown) provided in the, and the bending motion causes the bending portions 31, 32 and 33 to be bent and deformed.

In this embodiment, the bent portions 31, 32,
The thickness of the magnetic yoke 26 is set so that 33 is easily deformed.
It is thinner than that (by performing crushing or cutting). This not only makes it easier to deform the bent portions 31, 32, 33, but also prevents the magnetic yoke 26 itself from deforming.

In the above embodiment, the tilt correction is performed by tightening and deforming the bent portions 31, 32 and 33 using the screw rod (screw rod), but the following FIG. 3 and FIG.
The tilt correction may be achieved without using a screw rod (screw rod) as in the embodiment shown in FIG. Here, a plurality of bent portions 51, 52, 53 (for example, three as in this embodiment) are arranged in the same manner as in the above-described embodiment, and the bent portions 54, 55, 56 are provided. Base 30
Is bent in the direction of. Further, the base 30 is provided with a positioning recess 57, in which the bent portion 5 is provided.
The folded-back portions 61, 62, 63 of 8, 59, 60 are adapted to be fitted. Alternatively, here, the structure may be such that it is only fixed by means such as adhesion. In the figure, reference numerals 64, 65, 66 denote folding portions 61, 62,
It is an opening for fitting 63 into the positioning recess 57 of the base 30.

This tilt adjustment is performed by bending portions 51, 52, 5
By pressing 3 from above, the bent portions 51, 5
This is achieved by flexing 2,53 until it is plastically deformed. In this embodiment as well, the bent portions 51, 52, 53 are made thinner than the magnetic yoke 46 so that the bent portions 51, 52, 53 are easily plastically deformed. This not only makes it easier to deform the bent portions 51, 52, 53, but also prevents the magnetic yoke 46 itself from being deformed.

In this embodiment, the bent portion is bent in the direction of the base at the position of the bent portion, but the present invention is not limited to this, and the bent portion may extend parallel to the direction of the base. . Further, in the present embodiment, the method of supporting the objective lens portion by the leaf spring is adopted, but the present invention is not limited to this, and one using a bearing means such as a sliding shaft, a wire supporting method, a hinge. Other support methods such as bending may be used. Further, the base of the present embodiment corresponds to an optical head that incorporates a laser element and various optical components and emits and receives a laser beam. A separate type optical head in which parts are divided into a fixed side and a driving side may be used, or another method may be used, and the present invention is not limited to this.

The tilt correction is made entirely by bending the mounting portion of the magnetic yoke 26 to the base 30 described above.
However, as shown in FIG. 5, it may be additionally performed at the attachment position of the objective lens 1 to the lens holder 2. Here, the lens holder 2 is provided with a support portion 61 of the objective lens 1, and an adhesive 62 is interposed between the support portion 61 and the peripheral edge of the objective lens 1 with a required thickness. The tilt correction is performed so that the optical axis 25 of the objective lens 1 coincides with the optical axis 24 of the laser light. In particular, in this example,
In order to supply the adhesive 62, the end face 6 of the support portion 61 is
The L-shaped passage hole 64 opening to 3 is formed, and the thickness of the adhesive 62 on the end face 63 can be adjusted by adjusting the filling amount of the adhesive into each passage hole 64.

Further, in the embodiment shown in FIG. 6, a fitting groove 65 for receiving the objective lens 1 is formed on the top of the lens holder 2, and a dovetail groove 66 for inserting a spacer is formed in the support portion 61 at the periphery thereof. Alternatively, the spacer 67 may be formed appropriately, and the tilt correction by the adhesive 62 may be finely adjusted. Further, as shown in FIGS. 7 and 8, an annular groove 68 is formed on the lower surface of the peripheral edge portion of the objective lens 1, and a seat hole 69 is provided in the opening portion of the passage hole 64 on the opposing end surface 63 to bond the same. You may make it suppress the protrusion of an agent.

Further, as shown in FIG. 9, the lens holder 2 has a tongue-shaped support portion 7 for supporting the peripheral edge of the objective lens 1.
0 may be provided and the support portion 70 may be deformed to perform tilt correction so that the optical axis 25 of the objective lens 1 coincides with the optical axis 24 of the laser light. In this case, the adhesive 62 is applied between the peripheral surface of the objective lens 1 and the end surface of the lens holder 2.

In the present invention, as shown in FIG.
The magnetic yoke 26 is provided with a buoyant force on the lens holder 2 and is held at a neutral position (here, a current for energizing the coil is not passed) when adjusting the movement in the focus direction. That is, in this embodiment, the box-shaped tanks 71 are mounted on both sides of the lens holder 2 and located between the coil winding portions of the magnetic yoke 26. Gas having a low specific gravity (light) such as neon, methane, ammonia, and hydrogen is filled in the tank 71, and the filling hole 72 is closed by the plug 73 to seal the tank. In addition, in this embodiment, it is preferable that the tank 71 is configured as a cassette type and is detachably attached to the lens holder 2 by means such as fitting.

Therefore, the lens holder 2 is attached to the coil by
Even if the bias current is not always supplied, the neutral position is maintained, and thus the load of electrical control can be reduced. As a result, it is possible to avoid distortion of the leaf spring 5, vibrate at high speed due to seek operation, etc.
It is possible to avoid such an adverse effect that resonance occurs during vibration when the focus operation or tracking operation is performed.

[0026]

The present invention has been described in detail above. The objective lens for converging the laser light on the recording / reproducing surface of the recording medium is mounted on the lens holder, and the lens holder is mounted on the actuator base and the objective lens is mounted on the lens holder. The focus coil and the tracking coil are mounted on the lens holder in order to support the objective lens in the focus direction and the tracking direction orthogonal to this direction in a movable state and drive the objective lens in the focus direction and the tracking direction. At the same time, in the objective lens driving device equipped with a magnetic circuit including a magnetic yoke and a magnet on the actuator base side, means for fixing the magnetic yoke to the actuator base by deforming the mounting portion of the magnetic yoke is provided. The objective lens is equipped with the deformation of the mounting portion at this time. Since the tilt correction is performed so that the optical axis coincides with the optical axis of the laser beam, the tilt correction is surely performed by deforming a part of the magnetic yoke and pulling and tilting the entire magnetic yoke. In addition, the structure is relatively simple and the workability is good, and it is possible to obtain effects such as avoiding instability with respect to vibration that causes resonance in a driven state.

Further, the lens holder is provided with a support portion for the objective lens, and by deforming the support portion, tilt correction for making the optical axis of the objective lens coincide with the optical axis of the laser light is performed. Alternatively, the lens holder is provided with a support portion for the objective lens, and an adhesive, an adhesive member, or a spacer is provided between the support portion and the objective lens in a required thickness. Since it is configured to perform tilt correction by which the optical axis of the objective lens coincides with the optical axis of the laser light, the tilt correction can be surely performed by these as well. The structure is relatively simple and the workability is good, and it is possible to obtain effects such as causing resonance in a driving state and avoiding instability with respect to vibration.

Further, the lens holder can be held at the neutral position (origin) in the range of focus drive control without applying a bias current. For this reason, the load of electrical control can be reduced, and as a result, the strain on the leaf spring can be avoided, and resonance can occur when the objective lens vibrates at high speed such as a seek operation, or when the objective lens performs focus operation or tracking operation. It is possible to avoid the adverse effects that occur.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention.

FIG. 2 is a side view of the above embodiment.

FIG. 3 is a front view of another embodiment.

FIG. 4 is a side view of the above embodiment.

FIG. 5 is a vertical sectional side view showing a part of the present invention.

FIG. 6 is a partially exploded perspective view of the above embodiment.

FIG. 7 is an exploded perspective view of another embodiment.

FIG. 8 is a vertical sectional side view of the above embodiment.

FIG. 9 is a vertical sectional side view of still another embodiment.

FIG. 10 is a perspective view of a configuration in which a holding state of an objective lens is devised in the above example.

FIG. 11 is a perspective view of a conventional example.

FIG. 12 is a front view of a conventional example.

FIG. 13 is a side view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 3 Focus drive coil 4 Tracking drive coil 4 5 Leaf spring 6 Leaf spring mounting member 26 Magnetic yoke 27 Magnet 28 Outer yoke 29 Inner yoke 30 Base 31, 32, 33 Bent portion 34, 35, 36 Bending part 37, 38, 39 Folding part 40 (41, 42 not shown) Hole part 43, 44, 45 Screw rod (screw rod)

Claims (4)

[Claims] 1. An objective lens for converging laser light on a recording / reproducing surface of a recording medium is mounted on a lens holder, and the lens holder is mounted on an actuator base so that the objective lens has a focus direction and a tracking direction orthogonal to this direction. On the other hand, in order to support the objective lens in a movable state and drive the objective lens in the focusing direction and the tracking direction, the focusing coil and the tracking coil are mounted on the lens holder, and a magnetic circuit including a magnetic yoke and a magnet. In the objective lens driving device equipped with the actuator base side, there is provided means for fixing the magnetic yoke by attaching the magnetic yoke to the actuator base, and the attaching part is deformed at this time. The optical axis of the objective lens to match the optical axis of the laser light. An objective lens driving device, characterized in that it is configured to perform tilt correction. 2. An objective lens for converging a laser beam on a recording / reproducing surface of a recording medium is mounted on a lens holder, and the lens holder is mounted on an actuator base so that the focusing direction of the objective lens and a tracking direction orthogonal to this direction. On the other hand, in order to support the objective lens in a movable state and drive the objective lens in the focusing direction and the tracking direction, the focusing coil and the tracking coil are mounted on the lens holder, and a magnetic circuit including a magnetic yoke and a magnet. In the objective lens driving device equipped with the actuator base side, the lens holder is provided with a support portion for the objective lens, and by deforming the support portion, the optical axis of the objective lens is changed to the laser beam. Configured to perform tilt correction to match the optical axis of the light An objective lens driving device characterized in that 3. An objective lens for converging a laser beam on a recording / reproducing surface of a recording medium is mounted on a lens holder, and the lens holder is mounted on an actuator base so that a focusing direction of the objective lens and a tracking direction orthogonal to this direction. On the other hand, in order to support the objective lens in a movable state and drive the objective lens in the focusing direction and the tracking direction, the focusing coil and the tracking coil are mounted on the lens holder, and a magnetic circuit including a magnetic yoke and a magnet. In the objective lens driving device equipped with the actuator base side, the lens holder is provided with a support portion of the objective lens, and an adhesive, an adhesive member, or an adhesive member is provided between the support portion and the objective lens. A spacer having a required thickness is interposed, whereby the objective lens is The objective lens driving device is configured to perform tilt correction so that the optical axis of the laser beam coincides with the optical axis of the laser beam. 4. An objective lens for converging laser light on a recording / reproducing surface of a recording medium is mounted on a lens holder, and the lens holder is mounted on an actuator base so that the objective lens has a focus direction and a tracking direction orthogonal to this direction. On the other hand, in order to support the objective lens in a movable state and drive the objective lens in the focusing direction and the tracking direction, the focusing coil and the tracking coil are mounted on the lens holder, and a magnetic circuit including a magnetic yoke and a magnet. In the objective lens driving device equipped with the actuator base side, the lens holder is equipped with a float in which a gas having a specific gravity lower than that of air is enclosed in order to hold itself in the neutral position in the focus direction. An objective lens driving device characterized by being provided.