JP3084053B2 - Objective lens support device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens support device used for an optical information recording / reproducing device for optically writing or reading information.

[Conventional technology]

A conventional optical pickup is shown in FIG. 8 (JP-A-62-40627).
As shown in FIG. 1, an objective lens 31 is bonded and fixed to a holding member 32, and the holding member 32 is supported by a support member 33 in a first direction parallel to the optical axis of the objective lens 31 and in a first direction orthogonal to the optical axis. The base 34 is provided movably in two directions. On both left and right sides of the holding member 32, a focusing coil 35 and a tracking coil 36 are adhered, and the objective lens 31 is formed by an inner yoke 37, an outer yoke 38, and a magnetic circuit formed by a magnet 39. (Focusing direction) and a second direction (tracking direction).

[Problem to be solved by the present invention]

The conventional support member 33 has a parallel link portion 40 capable of moving in a first direction and a rotating hinge portion 41 capable of moving in a second direction, as shown in the drawing. It has a symmetrical shape. Then, the balancer 42 and the balancer 43 are held by the holding member so that the position of the center of gravity of the movable body is on the hinge axis of the rotating hinge portion 41 and coincides with the intersection of the parallel link portion 40 and the rotating hinge portion 41 on the vertical symmetry axis. 32 adhesively fixed. In this case, the balancer 42 balances up and down with respect to the vertical symmetry axis of the parallel link portion 40 and the rotating hinge portion 41. The balancer 43 balances the front and rear weights of the pivot hinge 41 with respect to the hinge axis. The balance between the upper and lower weights is such that when a force in the second direction acts on the movable body, a torsional moment is not generated in the support member 33 in a direction orthogonal to the first direction and the second direction. The reason for balancing the front and rear weights is that the movable body is turned in the second direction when a force in the second direction, which is generated when the movable body collides or is suddenly moved in a certain direction, acts. This is to keep them from moving.

As described above, in the conventional example, a large balancer is provided to balance the top and bottom, and the front and rear of the movable body. Therefore, there is a problem that the movable body becomes very heavy.

The present invention is proposed to solve the above-mentioned problem. The objective lens is shifted in the tracking direction even when an impact or acceleration from the second direction (tracking direction) acts while reducing the weight of the movable body. It is an object of the present invention to provide an objective lens supporting device that does not cause any unnecessary resonance.

[Means and actions for solving the problem]

In order to achieve the above object, the present invention provides an objective lens support device for an optical pickup that supports a movable body having an objective lens via an elastic support member so as to be displaceable. A parallel link portion movably supported in a first direction parallel to the axis; and a rotating hinge portion movably supported in a second direction orthogonal to the optical axis. An objective lens supporting device for an optical pickup configured such that a central axis of elastic deformation with respect to a force from a direction is shifted from a central axis of an outer shape of a parallel link portion and coincides with a center of gravity of a movable portion.

Further, in the objective lens support device of the optical pickup for supporting the movable body having the objective lens via the elastic support member so as to be displaceable, the elastic support member moves the movable body in the first direction parallel to the optical axis of the objective lens. It has a parallel link portion movably supported, and a rotating hinge portion movably supported in a second direction orthogonal to the optical axis, and an elastic deformation center of the rotating hinge portion with respect to a force from the second direction. An objective lens supporting device for an optical pickup, wherein an axis is shifted from a center axis of an outer shape of a rotation hinge part and is aligned with a center of gravity of a movable part.

With this configuration, it is possible to prevent a shift in the tracking direction of the objective lens and unnecessary resonance without using a balancer, so that the weight of the movable body can be reduced.

〔Example〕

1 and 2 show a first embodiment of the present invention. FIG. 1 is a plan view and a side view, and FIG. 2 is an exploded perspective view. The objective lens 1 is fixed to a holding member 2 by bonding or the like. The holding member 2 is movably supported in a first direction parallel to the optical axis of the objective lens 1 and a second direction orthogonal to the optical axis. It is provided on a base 4 having a spherical seat 4a via 3. On both sides of the holding member 2, a focusing coil 5 and a tracking coil 6 are adhered.
The base 4 is provided with a pair of inner yokes 7 and a pair of outer yokes 8, and a magnet 9 is adhered to a surface of the outer yoke 8 facing the inner yoke 7. A current is applied to the coil, which is disposed so that a part of the winding is located between the inner yoke 7 and the magnet 9, so that each of the yokes 7, 8 and the magnetic circuit formed by the magnet 9 are connected to each other. An electromagnetic force acts between them, and moves the objective lens 1 in the first direction and the second direction.

FIG. 3 shows details of the support member 3, wherein FIG. 3A is a plan view and FIG. 3B is a side view. This support member 3 is
As shown in the perspective view of the figure, a base 12 having a hole 11 for fitting two pins 10 provided on the base 4 is formed.
A parallel link portion 13 continuing to the base portion 12, a rotating hinge portion 14 continuing to the parallel link portion 13, and a rotating hinge portion 14.
And a connecting portion 15 for connecting to the holding member 2 continuously. Further, the parallel link portion 13 has arm portions 16 and 17 that are not deformed and hinge portions 18 to 21 and 22 to 25 that are deformed. The hinge portion is formed so that the thickness and the width are different between the upper and lower portions of the support member 3 so that the elastic deformation center axis X of the parallel link portion 13 with respect to the force from the second direction can be changed. It is shifted from Y.

By the way, in the case of a rectangular spring having a uniform cross section unlike the present embodiment, the spring force is represented by the following equation.

(Here, k = spring damage E = longitudinal elasticity coefficient 1 = spring length b = spring width h = spring thickness) Therefore, by appropriately selecting the values of b and h, the spring deformation in the first direction is kept constant. The spring force for the force in the second direction can be changed. For example, by setting the spring thickness to about 0.9 times and the spring width to about 1.37 times, the spring force acting as a normal spring remains unchanged, and the spring force in the direction orthogonal to this is reduced by about 2.3.
Can be doubled.

The parallel link portion 13 can be moved in the first direction by the hinge portions 18 to 25 being deformed as springs. Therefore, the vibration characteristic of the objective lens in the first direction does not change unless the spring force for the force in the first direction in this portion is changed. Therefore, in the present embodiment, the hinge portion 1
The hinge width is W1 and the hinge thickness is t1 at four locations of 8, 19, 22, and 23, and the hinge width is W2 and the hinge thickness is t2 at the four locations of the hinge portions 20, 21, 24, and 25. In addition, W1, W2,
By letting the relationship of W1 · t1 ³ = W2 · t2 ³ W1 ≠ W2 wait between t1 and t2, the spring force for the force in the first direction at the eight hinge portions is kept the same in the second direction. Hinges 18, 19, 2
It can be changed by changing 2, 23 and hinge portions 20, 21, 24, 25.

FIG. 4 shows side surfaces of the holding member 2 and the support member 3 which are movable parts. The holding member 2 includes an objective lens 1
In order to balance the weight of the left and right parts with the hinge axis Z interposed therebetween, the holding member 2 extends greatly on the opposite side to the plane direction with the part where the objective lens 1 is provided (A
Figure). And to avoid unnecessary weight increase of moving parts,
Since the balance in the vertical direction is not maintained, the center of gravity of the entire movable part is located at the point P near the upper portion of the holding member 2 as shown in the figure.

As shown in FIG. 4B, by changing the hinge width and the hinge thickness in the vertical direction of the hinge portion,
The center axis X of the elastic deformation with respect to the force from the direction is shifted upward from the center axis Y of the outer shape so as to pass through the point P of the center of gravity of the movable part. Therefore, when the movable portion is connected so as to be supported by the support body 3, even if a force in the second direction acts on the movable body, the support member 3 does not generate a torsional force. Unnecessary resonance can be suppressed. On the other hand, unlike the present embodiment, when the center axis X of elastic deformation of the support member 3 is made coincident with the center axis Y of the outer shape so as not to pass through the center of gravity P of the movable part, FIG. 5 (from the arrow direction in FIG. As shown in FIG. 1, when a force from the second direction acts, torsional resonance occurs.

FIG. 6 is a side view of a support member showing a second embodiment of the present invention. Parts corresponding to those in the first embodiment are denoted by the same reference numerals. In the present embodiment, the hinge portion has the same hinge width in both the upper and lower portions, while the entire support member 3 is divided into upper and lower regions, and the material of these regions is changed.

That is, the hinge width (having a different hinge thickness) is the same, and the upper and lower portions of the support member 3 are formed of different materials separately for the first region M1 and the second region M2. As described above, by changing the longitudinal elastic modulus E and the hinge thickness t of the material in the two regions, the center axis of the elastic deformation and the center axis of the outer shape are shifted. Then, the first area M1 and the second area M2
It is assumed that the following relational expressions are satisfied for the longitudinal elastic coefficients E1 and E2 and the hinge thicknesses t1 and t2.

E1 · t1 ³ = W2 · t2 ³ E1 ≠ E2 In this case, the hinge width may be fixed and the hinge thickness may be constant. In this case, the following relationship should be satisfied with the longitudinal elastic modulus and the hinge width. To

E1 · W1 = E2 · W2 E1 ≠ E2 In addition, all of the longitudinal elastic modulus, the hinge thickness, and the hinge width may be used as parameters to satisfy the following relational expression (furthermore, the hinge length may be added as a parameter. Good).

E1 · W1 · t1 ³ = E2 · W2 · t1 ³ E1 ≠ E2 As a method of changing the material for each region of the support member 3, there is a method of molding (two-color molding) using the above two kinds of materials. In addition, there is a method in which the regions formed separately are combined to form an integral support member 3.

As described above, in the present embodiment, the same effect as in the first embodiment is achieved by changing the material and the like for each region of the support member 3. Moreover, in the case of the present embodiment, the use of two types of materials allows the longitudinal elastic modulus to be used as a parameter, so that there is an effect that the design range is extremely widened.

FIG. 7 shows a third embodiment of the present invention. FIG. 7A is a side view, and FIG. In this embodiment, the dimensions of the upper and lower two pivot hinge portions are changed. In other words, the hinge thickness t is equal at the top and bottom (FIG. B), but the hinge width is
W1 and W2 are different. With such a configuration, a portion of the pivot hinge portion that is ahead of the pivot axis Z (the side of the connection portion with the holding member)
The center axis X of the elastic deformation and the center axis Y of the outer shape are shifted from each other. Then, by appropriately selecting the hinge widths W1 and W2, the center of gravity of the movable portion and the center axis of the elastic deformation are made to coincide with each other, so that the pivoting hinge portion is moved by the force from the second direction without providing the movable portion balancer. The generated torsional resonance can be suppressed.

In the present embodiment, the pivot hinge portion is connected to the upper and lower sides of the support member.
Although it is provided at each location, it may be configured to have three or more locations, or may be configured to be provided at one location that is shifted up or down.

〔The invention's effect〕

As described above, according to the present invention, the center of elastic deformation of the support member of the movable member with respect to the force from the second direction perpendicular to the optical axis is shifted from the center axis of the outer shape of the support member and coincides with the center of gravity of the movable member. Thus, it is possible to prevent the displacement in the second direction (tracking direction) and the occurrence of unnecessary resonance without adding a balancer to the movable body.

[Brief description of the drawings]

1A and 1B are a plan view and a side view according to a first embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIGS. 3A and B are a plan view and a side view of the support member. 4A and 4B are side views of the movable member, a plan view of the support member, FIG. 5 is a reference diagram for explaining a case where the support member causes unnecessary resonance, and FIG. 7A and 7B are side views and partial plan views of a support member according to a third embodiment of the present invention, and FIG. 8 is an optical pickup according to a conventional example. It is an exploded perspective view of a device. 12 Base 13 Parallel link 15 Connection 16, 17 Arm 18-21 Hinge X X Elastic deformation center Y Y External deformation center Z Z Hinge axis

Claims (2)

(57) [Claims] 1. An objective lens support device for an optical pickup, which displaceably supports a movable body having an objective lens via an elastic support member, wherein the elastic support member includes a first movable member parallel to the optical axis of the objective lens. A parallel link portion movably supported in the direction of the arrow, and a rotating hinge portion movably supported in a second direction orthogonal to the optical axis, and the elasticity of the parallel link portion against the force from the second direction. An objective lens supporting device, wherein a center axis of deformation is shifted from a center axis of an outer shape of a parallel link portion, and the center axis of deformation is matched with a center of gravity of a movable portion. 2. An objective lens supporting device for displaceably supporting a movable body having an objective lens via an elastic support member, wherein the elastic support member moves the movable body in a first direction parallel to an optical axis of the objective lens. It has a parallel link portion movably supported, and a rotating hinge portion movably supported in a second direction orthogonal to the optical axis, and an elastic deformation center of the rotating hinge portion with respect to a force from the second direction. An objective lens supporting device, wherein an axis is shifted from a center axis of an outer shape of a rotating hinge portion and is configured to coincide with a center of gravity of a movable portion.