JP2827185B2 - Objective lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an actuator base.
Focusing the objective lens holder on the support base
The present invention relates to an objective lens driving device having an improved mechanism for elastically supporting the object and the tracking direction .

[0002]

2. Description of the Related Art FIG. 7 shows a conventional objective lens driving device of this kind. Focusing direction (up-down direction: arrow Fo direction) on the support 2 fixed to the actuator base 1
One end of the upper and lower parallel links 3 that can be displaced is connected to each other, and a hinge 4 that is formed of a resin having elasticity and viscosity and that can be displaced in the tracking direction is provided as a tracking direction support mechanism on the distal end side of the parallel link 3. And an objective lens holder 6 having an objective lens 5 attached to the hinge 4. As a resin having elasticity and viscosity used for molding the hinge 4, a polyester elastomer, a polyamide elastomer, nylon 66, polybutylene terephthalate, or the like is conventionally used. Also,
A focusing coil 7 and a tracking coil 8 are mounted on the objective lens holder 6, and a magnet 9 and a yoke 10 for applying a magnetic field to these coils 7 , 8 are provided on the actuator base 1.

[0003]

However, since the hinge 4 of the conventional tracking direction support mechanism is formed by molding a resin, the shape of the hinge 4 is restricted depending on the selection of the material, and the characteristic such as sensitivity is increased. However, there was a drawback that variance easily occurred. Furthermore, since it is a resin, there is a disadvantage that its characteristics change with changes in temperature and humidity. Ma
Japanese Patent Application Laid-Open No. 2-94122 “Optical head device” includes:
Direction support in tracking direction and focusing direction
Using a metal leaf spring for tracking on the head body
The relay member is elastically supported through the relay member.
Including the objective lens through the leaf spring for focusing
There is disclosed an apparatus configured to elastically support a movable portion.
You. However, this device has a movable
Part cantilevered by four leaf springs for focusing
The tracking leaf spring elastically swings the relay member
It supports the tracking leaf spring.
The weight is four focuses outside the movable part including the objective lens.
The total weight is the sum of the shingle leaf spring and the relay member.
The leaf spring for tracking is movable directly including the objective lens
Support weight is larger than when supporting the part
Difficult to control attitude, that is, tracking control
And the swing radius of the objective lens is very large
Overcorrection to correct minute tracking errors
-High-precision tracking is inevitable due to shooting
Have problems such as not being able to desire control.
Was. Also, the leaf spring for focusing includes the objective lens
Four moving parts are supported, so the focusing plate
Because the neck flexes and deforms purely in the focusing direction
There is no torsional deformation in the bending deformation in the focusing direction.
It is easy to
Focusing control interference is unavoidable,
It is difficult to control the attitude with high accuracy.
Was something. Further, Japanese Patent Application Laid-Open No. Hei 2-66740.
"Objective lens actuator" has a tracking direction
Use a support member for each direction in the focusing direction
The lens holder is hinged pivot spring and a pair of hinged parallel
Of a structure connected to the actuator base via a leaf spring
An objective lens actuator is disclosed. But
However, this is a hinge forming an objective lens support mechanism.
Objective lens holder with two pivot springs and hinged parallel leaf springs
Together with the resin, and the above-mentioned conventional
As in the example, the choice of material caused restrictions on the shape
Characteristics, such as sensitivity, are likely to vary.
Is subject to changes in characteristics due to changes in temperature and humidity
It was something to have.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional drawbacks, and the tracking direction support mechanism of the objective lens has less restrictions on its shape, has less variation in characteristics, and has a characteristic which depends on temperature and humidity. It is an object of the present invention to provide an objective lens driving device in which the change of the lens is small.

[0005]

Means for Solving the Problems To achieve the above object,
Therefore, the present invention provides an objective lens for condensing light on a disc signal surface.
And an objective lens holder for holding the objective lens.
Drive in the focusing and tracking directions
Actuator and an actuator for supporting the actuator
Eta base and fixed on the actuator base
A support base, the base end of which is cantilevered by the support base;
A pair of plate-like parallel parts elastically displaced in the focusing direction
Material and the plate-like parallel member at the tip of the pair of plate-like parallel members.
Projecting with a separate member from the
Metal that supports the head in an elastic manner in the tracking direction
And a micro spring member made of the material.

[0006] Further , the metal minute spring member is made of viscoelastic material.
It is characterized by being covered with a body.

Further , the objective lens and the objective lens holder
The movable part including the metal minute spring member or the vicinity thereof
Is characterized by having a center of gravity.

[0008]

In the above arrangement, the objective lens is supported so as to be displaceable in the tracking direction by bending the metal micro spring member in the tracking direction. When the metal micro spring member is configured to be covered with a viscoelastic body, the driving characteristics in the tracking direction, that is, resonance is suppressed. In addition, the movable part has a center of gravity position at or near the metal minute spring member.
In this case, the impact of the impact on the objective lens is small.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of an objective lens driving device according to an embodiment of the present invention. In FIG. 1, a support base 2 is fixed on an actuator base 1, and one end of two upper and lower parallel links 3 displaceable in a focusing direction (vertical direction: arrow Fo direction) is connected to the support base 2. The support base 2 and the parallel link 3 are integrally formed of resin, and a connecting portion thereof is formed as a thin hinge portion 3a. A block 3b connecting the links 3 is formed integrally. In the present invention, the objective lens holder 6 on which the objective lens 5 is mounted and the block portion 3b of the parallel link 3 are connected by a metal micro spring member 11 which can be flexibly deformed in the tracking direction (the direction of the arrow Tr). doing. FIGS. 2 (FIG. 1), FIG. 3, FIG. 4, FIG. 5, FIG.
Are shown below. 7, a focusing coil 7 and a tracking coil 8 are attached to the objective lens holder 6, and a magnet 9 and a yoke 10 for applying a magnetic field to these coils 7, 8 are mounted on the actuator base 1. Are located in

In the embodiment shown in FIG. 2 (an enlarged part of FIG. 1), a single vertical microplate spring 11 is directly fixed to the objective lens holder 6 and the block 3b of the parallel link 3. It is. The micro-plate spring 11 is provided with a groove 6
a and 3c are formed, and these grooves 6a and 3c are preferably fitted and fixed using an adhesive.

In the embodiment shown in FIG. 3, a small leaf spring 11 is also provided with an objective lens holder 6 and a viscoelastic body 12 having elasticity and viscosity such as silicone rubber, butadiene rubber, and nitrile rubber. It is fixed to the block 3b of the parallel link 3. In this case, the viscoelastic body 12 is formed integrally with the micro leaf spring 11, and the viscoelastic body 12 is preferably fitted and fixed to the objective lens holder 6 and the grooves 6b and 3d provided in the block portion 3b of the parallel link 3 using an adhesive. .

Further, as shown in FIG.
One of the objective lens holder 6 side and the parallel link 3 side is directly fixed without interposing a viscoelastic body, and the other is
It may be fixed via.

In the embodiment shown in FIG. 5, a plurality of upper and lower, for example, two small plate-like springs 11A are arranged in parallel in the same vertical plane at intervals vertically, and are arranged on the objective lens holder 6 and the block 3b of the parallel link 3. It is fixed via a viscoelastic body 12.

The embodiment shown in FIG.
Are formed in a cylindrical shape by covering the whole with a viscoelastic body 12A. For example, two of these composite members are arranged in parallel in the same vertical plane at an interval above and below, and the objective lens holder 6 and the parallel link 3 It is fixed to the block 3b. In this case, a cylindrical hole may be formed in the objective lens holder 6 and the block portion 3b of the parallel link 3, and the composite member may be fitted and fixed to the cylindrical hole with an adhesive.

In each of the above embodiments, the minute spring members 11 made of metal are used as the tracking direction support mechanism.
Since A and 11B are used, it is easy to select a material, a thickness, and the like in accordance with characteristics to be designed, and thus it is easy to obtain characteristics such as sensitivity as designed. Further, since it is made of metal, it is possible to manufacture the shape with a certain degree of accuracy and to obtain a product having no variation in characteristics. Furthermore, since it is made of metal, there is little change in characteristics due to temperature and humidity, unlike resin. Also,
When the minute spring member is covered with the viscoelastic bodies 12 and 12A as in the embodiments of FIGS. 3, 4, 5 and 6, the transmission of the impact to the objective lens 5 is suppressed. And good characteristics can be obtained.

If the center of gravity of the movable portion including the objective lens holder 6, the focusing coil 7, the tracking coil 8 and the like is set to be substantially at the center of the minute spring members 11, 11A, 11B, the impact on the objective lens driving device is reduced. The influence on the objective lens 5 due to the addition is small.

In this embodiment, the parallel link 3 having the hinge portions 3a at both ends is used as a plate-like parallel member for supporting the objective lens so as to be displaceable in the focusing direction.
However, the present invention is not limited to this, and can be applied to, for example, a device using a parallel leaf spring that does not have a sheep portion and that bends and deforms as a whole. In short, the present invention can be applied to an objective lens driving device having a tracking direction support mechanism independent of the focusing direction support mechanism.

[0018]

According to the present invention, an actuator base is provided.
A pair of plates on which the support fixed on the cantilever supports the base end
A separate member from the plate-like parallel member may be provided at the tip of the plate-like parallel member.
Projecting a metal micro-spring member and holding the objective lens holder
Configuration that supports elastically swingable in the tracking direction
Therefore, considering the target tracking characteristics,
By designing the material and thickness of the metal micro leaf spring material,
The desired tracking characteristics can be easily obtained,
Processing is easy because the small leaf spring member is made of metal,
Since the dimensions can be manufactured with a certain degree of accuracy, the characteristics vary.
Product without any
Characteristics change due to temperature and humidity is small,
Such as maintaining stable tracking accuracy
It has excellent effects .

Further , the metal minute spring member is made of a viscoelastic material.
Driving characteristics in the tracking direction,
Resonance can be suppressed, and drive characteristics in the tracking direction
The effect is that the performance can be improved. Also,
The movable part is located at the center of gravity at or near the metal micro spring member.
The impact resistance is improved and the impact applied to the objective lens is improved.
This has the effect of reducing the effects of a shot.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of a tracking direction support mechanism in FIG.

FIG. 3 is a perspective view showing another embodiment of a tracking direction support mechanism.

FIG. 4 is a perspective view showing still another embodiment of a tracking direction support mechanism.

FIG. 5 is a perspective view showing still another embodiment of a tracking direction support mechanism.

FIG. 6 is a perspective view showing still another embodiment of a tracking direction support mechanism.

FIG. 7 is a perspective view showing a conventional objective lens driving device.

[Description of Signs] 1 Actuator base 2 Support base 5 Objective lens 6 Objective lens holder 9 Magnet (actuator) 10 Yoke (actuator) 11, 11A, 11B Metal micro spring member 12, 12A Viscoelastic body

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/09-7/095

Claims (3)

(57) [Claims] 1. An objective lens for condensing light on a signal surface of a disk.
And an objective lens holder for holding the objective lens.
Drive in the focusing and tracking directions
Actuator and an actuator for supporting the actuator
Eta base and fixed on the actuator base
A support base, the base end of which is cantilevered by the support base;
A pair of plate-like parallel parts elastically displaced in the focusing direction
Material and the plate-like parallel member at the tip of the pair of plate-like parallel members.
Projecting with a separate member from the
Metal that supports the head in an elastic manner in the tracking direction
An objective lens driving device , comprising: a minute spring member made of a material . 2. The metal minute spring member is a viscoelastic body.
2. The objective lens driving device according to claim 1, wherein the objective lens driving device is coated . 3. An objective lens comprising an objective lens and an objective lens holder.
The movable part is placed on or near the metal micro-spring member.
The objective lens driving device according to claim 1, wherein the objective lens driving device has a center position .