JPS6173248A - Objective lens driving device of optical recorder and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate the influence of sliding frictional force at the time of moving and, at the same time, to prevent a drop in control performance caused by the difference in attitude, by constituting an objective lens holding body, parallel springs, and intermediate supporting body in such a way that they rotate in one body around a rotating axis in the tracking direction. CONSTITUTION:The fixed section 6 of a base is supported by an intermediate supporting body 14 under a rotatable condition around a rotating axis formed by the spatial line of intersection of plate springs 16A and 16B. An objective lens holding body 8 and parallel springs 13A and 13B together with the intermediate supporting body 14 are fitted around an eccentric axis 18 including the rotating axis in one body under a rotatable condition and it is previously arranged that, when the rotating angle is small, an objective lens 2 moves in a direction which is almost equal to the tracking direction 11. Moreover, the plate springs 16A and 16B constituting a cross spring produce restoring force following to the rotation and maintain the neutral position of the tracking direction. If the plate springs 16A and 16B are prepared by using a visco-elastic material, such as plastic, fiber-reinforced plastic, rubber, etc., a damping characteristic which suppresses the amplitude when resonance occurs can be given to the springs 16A and 16B.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an objective lens driving device for an optical recording/reproducing apparatus that records or reproduces information on a recording medium using optical means, and in particular, to The present invention relates to an objective lens driving device suitable for easily and accurately controlling υ to follow an information track.

[Prior art]

An optical recording/reproducing device is used that records or reproduces information by focusing a light beam onto a recording medium using an objective lens.In this type of recording/reproducing device, the objective lens follows an information track. A controlled objective lens drive is provided.

This type of objective lens driving device detects whether or not the light spot is focused on the information track and is in a state where information can be recorded or reproduced reliably, and then controls the objective lens based on the error signal. Focus control that displaces the optical spot in the axial direction (focus direction), and tracking that detects the amount of deviation of the optical spot from the information track and displaces the objective lens in the direction perpendicular to the information track (tracking direction) based on the tracking error signal. control is performed.

When driving such an objective lens, the optical axis does not tilt when the objective lens is displaced in the focusing direction or the tracking direction, and the controls in each direction do not interfere with each other, and the objective lens can be moved independently and accurately in each direction. A device that can be moved is required.

A conventional objective lens driving device of this type, as disclosed in Japanese Patent Application Laid-Open No. 57-210456, has an objective lens mounted at a position offset from the center axis of the objective lens holding tube, and the objective lens is mounted on the center axis of the objective lens holding tube. The objective lens is moved in the tracking direction by rotating the objective lens holding cylinder around the fixed axis through a fixed shaft protruding from a part of the drive device housing, and the objective lens holding cylinder is attached to the fixed axis. An apparatus has been proposed in which the objective lens is moved in the focus direction by sliding along the lens.

In such an objective lens drive device, a coil that provides drive in the focusing direction and a coil that provides drive in the trunking direction are provided on the outer periphery of the objective lens holding tube, and these coils are arranged inside and outside the objective lens holding tube. The objective lens holding tube is arranged to cross a magnetic circuit consisting of a yoke and a permanent magnet provided in the lens, and the objective lens holding cylinder is held at a neutral point by an elastic member.

However, in the conventional objective lens driving device as mentioned above,
When the objective lens holding cylinder is driven in the focusing direction, the holding cylinder slides on the fixed shaft, which creates frictional force and causes a stick-slip phenomenon.

The drawback is that the sliding resistance increases significantly due to external conditions such as dew condensation, making it inoperable.

Furthermore, when the entire storage device is tilted, there is an increase in frictional force due to the difference in posture, which also has the drawback of causing instability in focus control and deteriorating control performance.

〔the purpose〕

The purpose of the present invention is to eliminate the drawbacks of the conventional structure as described above, eliminate the influence of sliding friction force when moving the objective lens holder (holding tube) in the focus direction, and reduce the control performance due to posture differences. It is an object of the present invention to provide an objective lens driving device for an optical recording/reproducing device that can eliminate the problem and improve the performance of focus control.

[Summary]

In the present invention, an objective lens holder that holds an objective lens is supported by an intermediate support via a parallel spring so as to be movable in the focus direction, and the intermediate support is moved to a position apart from the optical axis. The objective lens holder, the parallel spring, and the intermediate support are rotatably supported on a rotation support shaft consisting of cross springs provided in parallel, and are configured to rotate together in the tracking direction about the rotation support shaft. By doing so, the above objective is achieved.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 to 7.

In FIGS. 1 to 4, an objective lens hole 3 through which an objective lens 2 looks is formed in the center of a substrate l, and a figure-8-shaped yoke 4A with the open side facing upward is formed on both sides of the objective lens hole of the substrate. , 4B are fixed. Further, a substrate fixing portion 6 is provided at the illustrated position on the substrate 1, to which one end of the leaf springs 16A, 16B is fixed to the stepped portion. The lower end of this substrate fixing portion 6 is fixed to the substrate l by screws or adhesive.

The figure 8-shaped yokes 4A and 4B are made of a ferromagnetic material such as electromagnetic soft iron, and permanent magnets 7A and 7B are bonded to both sides of the central protrusion of each figure 8, with the same poles facing each other. This constitutes a magnetic circuit.

On the other hand, the objective lens 2 is fixed to an objective lens holder 8. A rectangular coil 10 that generates a driving force in the focusing direction (direction of arrow 9) is attached around the objective lens holder 8, and a driving force in the tracking direction (direction of arrow 11) is applied to the surface of the rectangular coil 10. A flat coil 12A is generated.

12B is glued.

The objective lens holder 8 includes a pair of upper and lower parallel springs L3A,
13B to the intermediate support 14, and is supported so as to be movable in the focus direction 9 without tilting the optical axis 5 of the objective lens 2 with respect to the intermediate support. Said parallel spring 13A
, 13B is, for example, metal, plastic, or FRP
It can be made from a viscoelastic material such as (R fiber reinforced plastic).

The intermediate support 14 is provided with a projection 15 that projects toward the objective lens holder 8 as shown in the figure. The above-mentioned plate springs 16A and 16B are attached to the stepped portion of the protrusion 15.
One end is fixed.

Further, the other ends of these leaf springs 16A and 16B are fixed to the stepped portion of the board fixing portion 6 as described above. These leaf springs are provided so as to intersect with each other at right angles through the notches of the leaf spring 16A, forming a cross spring structure as shown in a partial view in Figure 1. Therefore, the intermediate support body 14 is rotatably supported by the substrate fixing portion 6 with the spatial intersection line of the leaf springs 16A and 16B as a rotation axis.

In this way, the objective lens holder 8 and the parallel spring 13
A and 13B are integrally mounted with an intermediate support 14 so as to be rotatable around an eccentric shaft 18 including the rotational support shaft, so that when one rotation angle is small, the objective lens 2 moves approximately in the tracking direction 11. ing.

In addition, the leaf springs 1f3A and 16B constituting the cross spring are 1
A restoring force is generated along with the rotation, and the neutral position in the tracking direction is maintained. In addition, leaf spring 16A.

16B is plastic, mm reinforced plastic.

If it is made of a viscoelastic material such as rubber, it is possible to provide a damping characteristic that suppresses the amplitude when resonance occurs.

When assembling the objective lens drive device explained above,
First, the objective lens holder 8, parallel springs 13A, 13B, and intermediate support 14 are assembled and integrated, and as shown in FIG. 2, the square coil 10, the flat coil 12A,
Arrange it so that 12B fits into the gap between the figure 8-shaped yokes 4A and 4B.

Leaf springs 16A, 1 are installed between the protrusion 15 and the board fixing portion 6.
This is done by adhesively fixing 6B.

The driving of the objective lens holder 8, that is, the driving of the objective lens 2 in the trunking direction and the focusing direction is performed as follows. As shown in FIG. 6, when a magnetic field is acting in the direction of arrow 22, when current is passed through the flat coils L2A and 12B in the direction of arrow 23, a driving force is generated in the direction of arrow 24 according to Fleming's left hand rule. Therefore, this is a fixed rotation support for the objective lens holding body 8! This becomes a force for rotating around II6, and the objective lens 2 moves in the tracking direction.

On the other hand, when a current flows in the direction of arrow 25 through the rectangular coil 10, a driving force is generated in the direction of arrow 26, and the objective lens holder 8 is moved in the focusing direction ( Move to arrow 9) in FIG.

If the direction of the current (arrow 23.25) is reversed from that in Figure 5, we get
The driving force is also reversed, and tracking direction control and focus control are performed in the opposite direction.

When a driving force is generated in the tracking direction, the objective lens holder 8, parallel springs 13A, 13B, and intermediate support 14
The yoke 4 rotates as a unit around a rotating support shaft formed by a cross spring as shown by the broken line in FIG.
The rectangular coil 10 and the flat coils 12A, 12B inserted into the gap of the magnetic circuit formed by A, 4B8 and the permanent magnets 7A, 7B move a minute amount within the gap of the magnetic circuit. However, since the movable range of the objective lens 2 in the tracking direction is generally as small as about 0.5 am, the gap in the magnetic circuit does not need to be so wide, and a sufficiently strong magnetic field can be obtained.

Furthermore, if the inertia factors of the objective lens holder 8 and the intermediate support 14 regarding the rotational support shaft 6 are made equal to balance the inertia forces around the rotational support shaft, external vibrations applied to the objective lens driving device can be prevented. Accordingly, it is possible to obtain an objective lens driving device that is less affected by the effects of light and can be accurately and quickly controlled.

According to the embodiment described above, the movement of the objective lens 2 in the focus direction is performed only by elastic displacement of the parallel springs 13A and 13B. The focus control performance can be improved.

In addition, since the cross spring only rotates for movement in the tracking direction, and the support mechanisms for movement in the focus direction and tracking direction are completely separated, mutual interference between control operations in these directions can be eliminated. , This also makes it possible to improve control performance. Further, since the cross spring has a restoring force against rotation, it is possible to maintain a neutral position in the tracking direction and perform stable tracking without providing any means such as a restoring spring.

〔effect〕

As is clear from the above description, according to the present invention, the objective lens of an optical recording and reproducing device can easily and accurately perform focus control of an objective lens, and can eliminate mutual interference between focus control and tracking control. A lens drive device is provided.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing an embodiment of the objective lens driving device according to the present invention, Fig. 2 is a plan view of Fig. N41, Fig. 3 is a right side view of Fig. 2, and Fig. 4 is a diagram of Fig. 2. , FIG. 5 is a partial perspective view showing the structure of the cross spring in the embodiment shown in FIG. 1, FIG. 6 is an explanatory view showing the drive coil in FIG. FIG. 5 is an explanatory diagram showing the tracking operation of the apparatus shown in FIGS. 1 to 4; 1---One substrate, 2---One objective lens,
5---One optical axis, 6---Board fixing part. 7A, 7B---Ichihiku magnet. 8--1-1 objective lens holder. 9-----Focus direction movement. 10.12A, 12B-m-drive coil, 11--
−−−) Movement in racking direction. 13A, 13B---Uniparallel spring, 14-m-intermediate support, 15-m-protrusion. 16A, 16B----Single plate spring, 18-m-rotation center axis (eccentric axis), 22-m-magnetic field 24-------
Tracking direction driving force, 26-----7 Orcus direction driving force.

Claims (1)

[Claims] (1) In an objective lens driving device of an optical recording/reproducing device that records or reproduces information by condensing a light beam onto a recording medium using an objective lens, a first coil and an objective that drive the objective lens in the optical axis direction are used. an objective lens holder having a second coil that drives the lens in a direction perpendicular to the optical axis; one end is fixed to the objective lens holder and the other end is fixed to an intermediate support, and the objective lens holder is fixed to the intermediate support in the optical axis direction; A rotary support consisting of a parallel spring that supports the intermediate support so that it can move in the direction perpendicular to the optical axis, and a cross spring that is provided parallel to the optical axis at a distance from the optical axis to support the intermediate support so that it can rotate in a direction perpendicular to the optical axis. An objective lens driving device characterized by comprising a shaft.