JP3277709B2 - Two axis actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxial actuator for an optical pickup used for recording and reproducing signals on an information recording medium for data storage, such as a CD or MD.

[0002]

2. Description of the Related Art Conventionally, such a biaxial actuator for an optical pickup has been used for recording and reproducing signals on an information recording medium such as an optical disk. The actuator can move the objective lens provided on the support member in two directions, a focusing direction and a tracking direction.

[0003] Such a two-axis actuator is configured, for example, as shown in FIG. In FIG. 5, the biaxial actuator 1 has a lens holder 2 with an objective lens 2a attached to the tip, and a coil bobbin 3 attached to the lens holder 2 by bonding or the like.

The lens holder 2 has two ends perpendicular to the fixed part 4 by two pairs of leaf springs 5 having one end on both sides of the lens holder 2 and the other end fixed to the fixed part 4. That is, it is movably supported in a tracking direction indicated by reference numeral Trk and a focusing direction indicated by reference numeral Fcs.

The coil bobbin 3 is wound with a focusing coil and a tracking coil (not shown). When a current is applied to each coil, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke 6 attached to the fixed portion 4 and the magnet (not shown) attached thereto. .

According to the biaxial actuator 1 configured as described above, when a driving voltage is supplied to each coil from the outside, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke 6 and the magnet. Then, the coil bobbin 3 is moved in the directions of Trk and Fcs in the drawing. Thus, the objective lens 2a attached to the lens holder 2 is appropriately moved in the focusing direction and the tracking direction.

In this case, the leaf spring 5 is attached to the lens holder 2.
On both sides constitute parallel links as shown in FIG. Thereby, the leaf spring 5 is swingable against the tension of the leaf spring 5 as shown by an arrow A by fixing the right end portion of FIG. Therefore, the lens holder 2 supported at the left end of the leaf spring 5 is always translated without rotating, so that the optical axis of the objective lens 2a does not tilt.

[0008]

However, in the biaxial actuator 1 having such a configuration, the two pairs of leaf springs 5 are arranged at a height H, as shown in FIG. Therefore, there is a problem that the biaxial actuator 1 becomes thicker by the height H.

Further, two pairs of leaf springs 5 must be attached to the lens holder 2 in parallel with each other, and there is a problem that the cost of processing and assembling the leaf springs 5 becomes high. .

In view of the above, the present invention provides a lens holder which is held in parallel by a pair of leaf springs.
It is an object of the present invention to provide a two-axis actuator which is configured to be thin at a low cost.

[0011]

According to the present invention, there is provided a lens holder for holding an objective lens, a coil bobbin attached to the lens holder, a focusing coil and a tracking coil wound around the coil bobbin. A coil, wherein the lens holder is supported by a fixed portion via a leaf spring, and wherein the leaf spring is deformed in one direction and a portion deformed in the opposite direction. This is achieved by a biaxial actuator for an optical pickup comprising a pair of leaf springs having the following.

In the two-axis actuator of the present invention,
Preferably, the leaf spring includes a portion extending from the fixing portion, a folded portion following the portion, and a portion connected to the lens holder from the folded portion.

[0013] In the biaxial actuator of the present invention, preferably, the leaf spring is connected to the lens holder so as to extend in the lateral direction.

Further, in the biaxial actuator of the present invention,
Preferably, the leaf spring is disposed on a lens holder.
They are connected so as to extend in the longitudinal direction.

[0015]

According to the above construction, since the leaf spring supporting the lens holder is formed so as to be folded in the opposite direction on the way, the lens holder is energized by energizing the focusing coil provided on the lens holder. When the leaf spring is moved along the optical axis direction, the bent portion from the fixed portion bends in the opposite direction to the portion from the folded portion to the lens holder. Thus, the lens holder will substantially always translate.

Further, since the lens holder is supported by the fixed portion by only a pair of leaf springs, the lens holder and the entire biaxial actuator are configured to be thin.

[0017] The leaf spring is arranged on the lens holder.
When connected in the horizontal direction, the leaf spring is connected to the lens holder in the same manner as in the related art.

[0018] The leaf spring is arranged so that
When connected so as to extend in the longitudinal direction, the extension of the leaf spring on both sides of the lens holder becomes relatively small.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to FIGS. In addition, since the Examples described below are preferred specific examples of the present invention, various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

FIG. 1 shows a first embodiment of a biaxial actuator according to the present invention. In FIG. 1, the biaxial actuator 10 includes a lens holder 11 for holding an objective lens 11a, and a coil bobbin 12 attached to the lens holder 11 by bonding or the like.

The lens holder 11 is fixed to the fixing part 13 by a pair of leaf springs 14 having one end fixed to both sides of the lens holder 11 and the other end fixed to the fixing part 13.
Are supported so as to be movable in two directions, that is, a tracking direction indicated by reference numeral Trk and a focusing direction indicated by reference numeral Fcs.

The coil bobbin 12 is wound with a focusing coil and a tracking coil (not shown). When a current is applied to each coil, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke 15 attached to the fixed portion 13 and the magnet attached thereto.

Further, each of the leaf springs 14 is formed so as to be folded in the opposite direction on the way. That is, FIG.
As shown in FIG. 3, the leaf spring 14 is moved from point a, which is a connection point to the lens holder 11, to an intermediate point b toward one side.
It comprises a first portion 14a extending to a point and a second portion 14b extending from point b to the opposite side to point c which is a connection point to the fixing portion 13. In this case, the first portion 14a of the leaf spring 14 is connected to a portion extending in the lateral direction with respect to the lens holder 11.

The biaxial actuator 10 according to the present embodiment
Is configured as described above. In the case of focusing, when the focusing coil wound around the coil bobbin 12 is energized, the magnetic flux generated in the focusing coil and the magnetic flux flowing through the magnet and the yoke 15 are formed. Interaction with the lens holder 11
, A force in the focusing direction Fcs acts.
As a result, the leaf spring 14 is elastically deformed as shown in FIG.
Is moved in the focusing direction Fcs, and the objective lens 1
Focusing 1a is performed.

Here, the condition that the optical axis of the objective lens 11a of the lens holder 11 does not substantially tilt due to the elastic deformation of the leaf spring 14 as described above, that is, the condition that the moment at the point a is not generated is as follows. Is described. That is, in FIG. 3, the length L1, L2 and the width W of the first portion 14a and the second portion 14b of the leaf spring 14 are shown.
1, W2, the moment at a distance X from point b is M, and the moment of inertia is I1 = I2.
Y ″ 1, y ″ 2 of 14b is

[0026]

(Equation 1)

(Equation 2)

## EQU1 ## Also, the slope y′1,
y'2 is

[0028]

(Equation 3)

(Equation 4)

## EQU1 ## In order for point a to be horizontal, y '
It is sufficient that 1 = y′2. Therefore,

(Equation 5) Becomes

Here, for example, when L1 = L2, I
1 = I2, and the leaf spring width W1 = W2. In this case, the slope y ′ at the point b is

(Equation 6) Becomes

In the above-described embodiment, the case where no moment is generated in the movable portion of the biaxial actuator 10 has been described. However, the present invention is not limited to this case. In the case of shifting in the jitter direction), the respective parts 14a, 14a of the leaf spring 14 are moved so that the point a including the generated moment moves in parallel.
It is possible to cope with this by selecting the width and length of b.

FIG. 4 shows a second embodiment of the biaxial actuator according to the present invention. In FIG. 4, the biaxial actuator 20 has a lens holder 11 for holding the objective lens 11a, and a coil bobbin 12 attached to the lens holder 11 by bonding or the like.

The lens holder 11 is fixed to the fixing part 13 by a pair of leaf springs 21 having one end fixed to both sides of the lens holder 11 and the other end fixed to the fixing part 13.
Are supported so as to be movable in two directions perpendicular to the camera, that is, in a tracking direction and a focusing direction.

The coil bobbin 12 is wound with a focusing coil and a tracking coil (not shown). When a current is applied to each coil, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke attached to the fixed portion 13 and the magnet attached thereto.

The above configuration is the same as the configuration of the biaxial actuator 10 shown in FIG. 1, but in the biaxial actuator 10 according to the present embodiment,
1 are formed so as to be folded in the opposite direction on the way. That is, the leaf spring 21 moves from point a, which is a connection point to the lens holder 11, to an intermediate point b toward one side.
It comprises a first portion 21a extending to a point, and a second portion 21b extending from point b to the opposite side to point c which is a connection point to the fixing portion 13. In this case, the first portion 21 a of the leaf spring 21 is directly connected to the first portion 21 a extending in the longitudinal direction with respect to the lens holder 11.

The biaxial actuator 20 having such a configuration
According to the two-axis actuator 10 shown in FIG.
Since the first portion 21a extending in the longitudinal direction of the leaf spring 21 is directly connected to the lens holder 11, the overall structure is small.

Therefore, in the above-described embodiment, since the leaf spring supporting the lens holder is formed so as to be folded in the opposite direction from the middle, the lens holder substantially always moves in parallel. Therefore, the configuration is simplified, and the processing cost and the assembly cost are reduced. Further, since the lens holder is supported by the fixed portion only by the pair of leaf springs, the lens holder and the entire biaxial actuator are configured to be thin.

The thickness or the width of the leaf spring can be increased, and conversely, the movable portion of the biaxial actuator can be reduced in weight. When the leaf spring is connected to the lens holder in the lateral direction, the leaf spring is connected to the lens holder in the same manner as in the related art. Therefore, the leaf spring can be easily attached to the lens holder by the same method as in the related art.

When the leaf spring is connected to the lens holder in the longitudinal direction, the extension of the leaf spring on both sides of the lens holder becomes relatively small. Therefore, the entire biaxial actuator is configured to be small.

In the above embodiment, each of the two-axis actuators 10 and 20 is formed in a U-shape at a point b which is an intermediate point between the leaf springs 14 and 21. The present invention is not limited to this, and may be formed in a “U” shape. Even if the whole is formed in a “V” shape, it is obvious that the same effect can be obtained.

[0041]

As described above, according to the present invention, the lens holder is held in parallel by a pair of leaf springs, so that the whole is made thin and at low cost. An axis actuator can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a biaxial actuator for an optical pickup according to the present invention.

FIG. 2 is a schematic plan view showing the configuration of the biaxial actuator of FIG.

FIG. 3 is a schematic view showing a deformed state of a leaf spring in the biaxial actuator of FIG. 1;

FIG. 4 is a schematic plan view showing the configuration of a second embodiment of a biaxial actuator for an optical pickup according to the present invention.

FIG. 5 is a schematic perspective view showing an example of a conventional two-axis actuator for an optical pickup.

FIG. 6 is a schematic view showing a deformed state of a leaf spring in the biaxial actuator of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Biaxial actuator 11 Lens holder 11a Objective lens 12 Coil bobbin 13 Fixed part 14 Leaf spring 14a First part 14b Second part 15 Yoke 20 Biaxial actuator 21 Leaf spring 21a First part 21b Second part

Claims (3)

(57) [Claims] 1. A lens holder for holding an objective lens, and the lens holder is held via a pair of leaf springs.
A biaxial actuator having a fixed portion, wherein the plate spring has a portion connected to the lens holder.
And the portion connected to the fixed portion
Is provided, and from the portion connected to the lens holder,
A first part up to the point, and
The second part up to the part connected to the fixed part is in the optical axis direction
A biaxial actuator for an optical pickup, characterized in that the actuator is bent along the axis. 2. The biaxial actuator according to claim 1, wherein the leaf spring is connected to the lens holder so as to extend in a lateral direction. 3. The biaxial actuator according to claim 1, wherein the leaf spring is connected to the lens holder so as to extend in the longitudinal direction.