JPH02177132A - Method and device for driving objective lens - Google Patents

Abstract

PURPOSE:To execute the access control at a high speed by fixing an oscillating member to a unit body so that it cannot be oscillated in the tracking direction and fixing magnetically an objective lens holding body to the oscillating member at the time of high speed track access. CONSTITUTION:An objective lens holding body 11 is freely oscillatable in the tracking direction T against an oscillating member 31, and on the other hand, the oscillating member 31 is freely oscillatable in the focus direction F against a unit body 29, but cannot oscillate in the tracking direction T. At the time of a high speed tracking access, by allowing magnetic force to work between the oscillating member 31 and the objective lens holding body 11 supported by this oscillating member 31, they are locked. Accordingly, even if the objective lens holding body 11 together with the unit body 29 moves at a high speed, the objective lens holding body 11 comes not to oscillate in the tracking T direction by its acceleration. In such a way, at the time of a high speed track access, the objective lens holding body can be locked, and the access control can be executed at a high speed.

Description

[Detailed Description of the Invention] The present invention optically reads and writes information by irradiating a light spot onto an optical recording medium such as an optical disk, magneto-optical disk, or optical card. The present invention relates to an objective lens driving method and apparatus for controlling the position of an objective lens that irradiates a light spot relative to a recording medium.

In unidirectional spot irradiation, the objective lens is controlled and driven in the focusing direction and the tracking direction. One of the driving methods is to fix the holder to which the objective lens is attached to the unit body via a flexible member, and use this flexure to drive the objective lens holder for focusing and tracking using a magnetic drive mechanism. be.

FIG. 6 is a plan view showing such a conventional objective lens driving device, and FIG. 7 is a sectional view taken along the line 1-2.

However, the magnetic drive member is not shown. Further, for convenience of explanation, the flexible member 510 is shown with halftone dots, and the objective lens 130 is shown with hatching in the plan view.

The objective lens holder 110 equipped with the objective lens 13 is
It is fixed to the unit main body 290 of the drive device by a flexible member 510 made of an integrally molded resin product.

The flexible member 510 has thin parts A, B,
B, C, and C are formed, and the thin part A acts as a bending hinge part in the tracking direction, and the thin parts B, B,
C and C act as bending hinges in the focus direction.

In the tracking direction, the thin flexible hinge part A is used as a fulcrum and arcuate movement is performed in the direction indicated by the arrow T in FIG.

B, C, and C move the objective lens 130 up and down as shown by arrow F, thereby displacing the objective lens 130.

However, it is inevitable that the overall weight will be unbalanced between the objective lens side centering on the hinge portion A of the objective lens holder 110 and the opposite side. Even if a balancer or the like is used to sufficiently balance the two at the time of design, it is difficult to maintain a strict balance in the final product due to variations in molded products, adhesives during assembly, wiring during mounting, etc.
Almost impossible in practice. Therefore, when performing high-speed tracking access to the entire unit, the objective lens holder is displaced in the tracking direction due to acceleration, and during close access, vibration is induced and the tracking operation is started, which delays access and prevents faster control. There is.

Furthermore, since the flexible member 510 is an integrally molded resin product, it can be said that the flexible member 510 is simplified by itself if attention is focused only on its component configuration. However, since its characteristics depend on the molding conditions of the resin, changes in hinge thickness, molding distortion, etc.
Variations in the resin spring, viscosity, etc. occur during the objective lens displacement operation, which becomes a factor that makes the drive control of the objective lens unstable. Moreover, since it is an integral structure, the movements in the focusing direction and the tracking direction affect each other, making it difficult to control the objective lens.

SUMMARY OF THE INVENTION The present invention provides an objective lens driving method and apparatus that can lock an objective lens holder during high-speed tracking access and also that can stably control the objective lens holder.

The objective lens driving method of the present invention fixes the objective lens holder to the unit body so as to be able to swing in the tracking direction and the focusing direction by a swinging member, and enables high-speed track access by moving the unit body; In an objective lens drive method that provides close access to the objective lens holder in the tracking direction and focus direction, the swinging member is fixed to the unit body so that it cannot swing in the tracking direction, and during high-speed track access, the objective lens is held It is characterized by magnetically fixing the body to the swinging member.

Further, the objective lens driving device of the present invention is an objective lens driving device in which an objective lens holder is fixed to a unit main body so as to be swingable in a tracking direction and a focusing direction.

The objective lens holder is swingably fixed to the relay member via a first leaf spring whose deflection direction is the tracking direction.

The relay member is swingably fixed to the unit main body via a second plate spring whose deflection direction is in the focus direction, and the relay member has an end opposite to a joint end with the objective lens holder. having a first magnetic member on the side;
A pair of second magnetic members are provided on the objective lens holder portion facing the magnetic member, and a pair of second magnetic members are provided so as to sandwich the first magnetic member apart from both sides, and either of the first and second magnetic members is provided. It is characterized in that one of the two is made up of a coil.

The objective lens holder is fixed to the unit main body via a swinging member. The objective lens holder is swingable in the tracking direction relative to the swinging member. On the other hand, the swinging member that supports the objective lens holder in this manner is swingable in the focusing direction with respect to the unit body, but cannot swing in the tracking direction.

During high-speed tracking access, there is a swinging member fixed to the unit body that can swing in the focus direction but not swingable in the tracking direction, and an objective lens holder supported by this swinging member. By applying a magnetic force between them and locking them, even if the objective lens holder together with the unit body moves at high speed, the objective lens holder will not swing in the tracking direction due to this acceleration. Therefore, in the device of the present invention using a flexible member having two plate spring relay members, current is passed through the coil to cause a repulsive force to work between the first magnetic member and the second magnetic member. Lock the objective lens holder and
It is possible to prevent the objective lens holder from being displaced in the tracking direction due to acceleration.

During close access, by releasing the lock caused by magnetic force, such as by stopping the flow of current to the coil, the objective lens holder becomes free to swing in the tracking direction and performs normal tracking and focusing operations. .

When operating in the focus direction, due to the deflection of the second leaf spring,
A relay member fixed to this leaf spring.

The first leaf spring and the objective lens holder swing together, and the objective lens holder moves up and down with respect to the unit body.

On the other hand, during the tracking direction operation, the objective lens holder swings relative to the relay member due to the deflection of the first leaf spring.

In this way, the tracking operation and the focusing operation do not affect each other, and the characteristics of the unloaded spring can be almost the same at the time of design and manufacture, so unstable factors are reduced and the control characteristics are stabilized.

However, FIG. 1 is a top view showing the objective lens driving device of the present invention.
Figure 2 is a side view of the main part with the magnetic drive mechanism omitted;
The figure is a vertical sectional view of FIG. 2 (a sectional view of the main part along 4@at-m in FIG. 1), and FIG. 4 is a top view of the main part of the second leaf spring 3.
3 is a top view with part 3 removed.

A focusing coil 15 is wound around the surface of the objective lens holder 11 to which the objective lens 13 is fixed, and
Four tracking coils 17 are attached.

The objective lens holder l1 is attached to the unit main body 2 so that the device single coil l5 and the tracking coil 17, which are composed of the driving magnet 21, the outer yoke 23, and the inner yoke 19, are arranged.
It is supported by 9.

The objective lens holder 11 is attached to the relay member 35 via a first leaf spring 3l. As can be seen from, for example, FIGS. 3 and 4, the first leaf spring 31 is a leaf spring whose surface expands in the vertical direction in FIG. 3, that is, in the focus direction (arrow F). The direction of deflection of the spring 31 is aligned with the tracking direction T. Therefore, the objective lens holder 11 is supported by the relay member 35 so as to be swingable in the tracking direction T by the first leaf spring 31.

On the other hand, the relay member 35 includes a pair of second leaf springs 33 . 33', the unit body 29
Fixed. second leaf spring 33;

Reference numeral 33' has a surface that extends in the paper plane direction of FIG. 1, that is, in the tracking direction, and the deflection direction of this leaf spring is aligned with the focus direction F. Therefore.

Second leaf spring 33. 33', the relay member 35 that supports the objective lens holder 11 is supported so as to be swingable in the focus direction F with respect to the unit body 29.

In addition, the first leaf spring 31 and the second leaf spring 33, 33'
This means that the expanding surfaces are orthogonal and the rocking force directions are orthogonal, so the rocking of the first leaf spring 31 affects the rocking of the second leaf spring 33, 33'. There is no, and also,
The reverse is also true.

The objective lens holder 11 has a notch 11a in which the relay member 35 is disposed.

The first and second leaf springs 31, 33, and 33' are made of materials and have thicknesses set to be lightweight and sufficiently vibration-proof, in order to suppress the resonance of the leaf springs that occurs during operation. It is desirable to have a structure in which an elastic body such as rubber is laminated and integrally fixed to a metal elastic plate. In addition, in order to suppress resonance, in addition to this rubber laminated fixing structure, as shown in FIGS. 5A and 5B [1], it is necessary to The fixed side of the unit body 29 of .33' is a rubber elastic body 4 set for the same purpose.
A similar effect can be obtained even if the structure is sandwiched by 1.41'.

For close access, drive magnetic [19,21゜23
When the tracking coil 17 performs a tracking operation, a force is applied to the objective lens holder 11 in the tracking direction T according to the signal, the first release spring 31 is bent, and the objective lens holder 11 is moved in the tracking direction T. Operate. At this time, the first temporary spring 31 and the second leaf spring 33.
33' are coupled via the relay member 35, and as described above, the directions of their swinging forces are set to be orthogonal to each other, so that the swinging of the first leaf spring 31 is the same as that of the second leaf spring 33'. The movement of the leaf springs 33 and 33' is not affected.

Similarly, during close access, the driving magnetic devices 19, 2
1.23 and the focusing coil 15, force is applied to the objective lens holder 11 in the focusing direction F according to the signal, and the second leaf spring 33, 33' is bent, causing the objective lens holder 11 to bend. 11 operates in the focus direction F.

Also at this time, the swinging of the second leaf springs 33, 33' does not affect the movement of the first leaf spring 31, as described above. In this way, the movements in the tracking direction T and the focus direction F can be performed separately to prevent the two from influencing each other.

Also, leaf springs are different from synthetic resin molded products.

It is possible to substantially match the characteristics at the time of design and at the time of manufacture, and it is possible to obtain stable drive characteristics in accordance with the design characteristics. Furthermore, the objective lens holder 11 is attached to the unit main body 2.
The swinging member supported by 9 is a thin leaf spring 31, 33.
' and a relay member 35 made of resin or the like, the volume of the portion corresponding to the hinge can be reduced compared to the conventional example shown in Figs. 6 and 7, making it possible to reduce weight and size. Become.

During a high-speed tracking operation, the unit main body 29 itself moves at high speed in the direction of the paper in FIG.

At this time, the relay member 3 that supports the objective lens holder 11
5 is supported so as to be able to swing freely in the plane of the paper with respect to the unit main body 29, so it is displaced by acceleration during high-speed track access, induces free vibration of the movable part during close access, and impedes stable high-speed control. become.

In the embodiment shown in FIGS. 1 to 4, the magnet is attached to the end of the relay member 35 opposite to the first leaf spring 31, taking advantage of the fact that the tracking direction and the focus direction operate separately as described above. established.

The notch 11a of the objective lens holder 11 and the magnet 37
Protrusions 11b and llb' are provided at positions facing the N and S poles of the magnetic poles at a distance from and facing these magnetic poles, and these protrusion coils 39 and 39' are wound.

During high-speed track access, a current is applied to the coils 39 and 39' to generate a counterforce between the coils 39 and the magnet 37, so that even when acceleration is applied, the relay member 35 and the objective lens holder connected thereto are maintained. The body 11 can be fixed (locked) in a neutral position.

Note that the circuit is configured to stop passing current to the coil after high-speed track access is completed, and to release the locking function during close access.

In addition, the relay member and objective lens holder are magnetically locked during high-speed access and free during close access.1 For example, a magnet may be attached to the objective lens holder and a coil may be provided to the relay member. , can take an appropriate configuration.

According to the present invention, the objective lens holder is swingably supported with respect to the unit body, and a magnetic fixing member is provided between the swinging member and the objective lens holder that can be controlled to turn on and off. By providing means and locking the objective lens holder against the swinging member during high-speed track access, the flexible member (swinging member) supporting the objective lens holder on the unit body can be adjusted in the tracking direction and focus, respectively. The following effects can be obtained by constructing the first and second leaf springs whose deflection directions are set in the same direction, and the relay member provided between the drawing leaf springs.

■ The objective lens holder can be locked during high-speed track access, enabling faster access control.

■ By forming the flexible member mainly using a helical leaf spring, which has almost the same characteristics at the time of design and manufacture, variations are reduced and it becomes possible to drive the objective lens in accordance with the design values.

(2) Since the deflections in the focus and tracking directions operate independently, movements in either direction do not affect each other, making control easy.

[Brief explanation of the drawing]

Fig. 1 is a top view of the objective lens driving device of the present invention, Fig. 2 is a side view of its main parts, Fig. 3 is a vertical cross-sectional view of Fig. FIG. 3 is a top view of main parts excluding a leaf spring 33. FIG. FIGS. 5A and 5B are explanatory diagrams showing a structure in which an elastic body is sandwiched. Fig. 6 is a top view showing a conventional objective lens driving device;
The figure is a sectional view thereof. II...Objective lens holder I3...Objective lens 1
5...Focusing coil 17...Tracking coil 19...Inner yoke 23...Outer yoke 33, 33'...Second leaf spring 37...Control magnet 41, 41'... Elastic body 21... Drive magnet 31... First plate spring 35... Relay member 39, 39'... Coil 51... Flexible member Fig. 1

Claims (1)

[Claims] 1. The objective lens holder is fixed to the unit body so as to be swingable in the tracking direction and the focusing direction by a swinging member, so that high-speed track access by movement of the unit body and the movement of the objective lens holder In an objective lens driving method that provides close access in the tracking direction and focus direction, a swinging member is fixed to the unit body so as not to swing in the tracking direction, and during high-speed track access, the objective lens holder is fixed to the swinging member. An objective lens driving method characterized by magnetically fixing the objective lens to a target lens. 2. In the objective lens drive device in which the objective lens holder is fixed to the unit body so as to be swingable in the tracking direction and the focusing direction, the objective lens holder is connected to the relay member via the first leaf spring whose deflection direction is the tracking direction. The relay member is swingably fixed to the unit main body via a second plate spring whose deflection direction is the focus direction, and the relay member is connected to the objective lens holder. A first magnetic member is provided on the end side opposite to the end; and a pair of the first magnetic members are sandwiched between the lens holder portion facing the first magnetic member and spaced apart from both sides. the second of
What is claimed is: 1. An objective lens driving device comprising: a magnetic member; and at least one of the first and second magnetic members comprising a coil.