JP2712088B2 - Leaf spring mechanism and optical disk device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a leaf spring mechanism and an optical disk apparatus using the same.

(Prior Art) The leaf spring mechanism is configured by arranging two or more leaf springs substantially in parallel, holding one end of these leaf springs and fixing an object to the other end, and bending the leaf springs. By operation, this object is moved in a direction perpendicular to the surface direction of formation. The leaf spring mechanism is used, for example, for moving an objective lens in a focusing direction in an optical disc device.
The objective lens can be moved in the surface direction of the optical disk, that is, in the focusing direction while the optical axis of the objective lens substantially matches the target information stored on the optical disk.
As an example of the use of such a leaf spring mechanism, there is an invention disclosed in Japanese Patent Application Laid-Open No. 61-123030 shown in FIG. The present invention
It is characterized in that two isosceles triangular leaf springs 101 and 102 are arranged in parallel, and the objective lens 103 is fixed at the apex of the leaf springs 101 and 102, whereby the vibration of the objective lens 103 in the focusing direction 104 and tracking direction 105 is achieved. By reducing the moment of inertia of the rotating member 106 while improving the characteristics, high-speed access can be performed with a small force.

To form the leaf spring mechanism 100, the upper and lower leaf springs 10 are used.
In order to maintain the parallelism of 1,102, first, the isosceles triangular leaf springs 101, 102 are accurately positioned together with the objective lens fixing base 107 and the rotating member 106, and then they are integrally formed to form the isosceles triangular shape. The top and bottom must be fixed. Generally speaking, it is most convenient for mass production if they are accurately positioned and then fixed by injection molding. In this case, durable beryllium copper, phosphor bronze, stainless steel or the like is used as a material of the leaf springs 101 and 103, and a thermosetting resin such as plastic is used as a material used for injection molding.

However, since these materials have different coefficients of thermal expansion, distortion occurs during cooling after injection molding, and this appears as a deviation in the parallelism of the leaf spring. Therefore, in the completed leaf spring mechanism, the movement characteristics of the leaf spring in a direction perpendicular to the surface direction (curved direction) become non-linear. Also, when this leaf spring mechanism is used in an optical disc device, the resonance frequency in the plane direction of the leaf spring, that is, the tracking direction is significantly reduced, and a servo band required for controlling the optical disc device can be sufficiently obtained. Will be gone.

(Problems to be Solved by the Invention) As described above, when the leaf spring mechanism is to be formed by injection molding, the parallelism of the leaf spring is determined by the difference in the coefficient of thermal expansion between the material of the leaf spring and the material used for injection molding. There was a difference in degrees. Therefore, the completed leaf spring mechanism has a non-linear movement characteristic in the bending direction.
When this leaf spring mechanism is used in an optical disk device, the resonance frequency in the direction perpendicular to the bending direction, that is, in the tracking direction, is significantly reduced, and the servo band required for controlling the optical disk device cannot be sufficiently obtained. There was a fear that it would.

The present invention has been made in view of the above problems,
Provide a leaf spring mechanism that can suppress non-linear movement characteristics in the bending direction even if affected by the coefficient of thermal expansion during cooling after injection molding, and without reducing the resonance frequency in the tracking direction It is another object of the present invention to provide an optical disk device capable of sufficiently securing a servo band required for controlling the optical disk device.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, in the present invention, at least two leaf springs each having a hole and formed in a substantially triangular shape are provided by injection molding. Formed at the vertex of the leaf spring,
A connecting member for connecting the leaf springs substantially in parallel, and by setting two of the connecting members to fixed sides,
Another one of the connecting members is a leaf spring mechanism that is movable in a direction perpendicular to a surface direction of the leaf spring.

Further, at least two leaf springs each having a hole, and a connecting member formed by injection molding at least three places around the hole of the leaf spring and connecting the leaf springs substantially in parallel with each other. A leaf spring mechanism in which at least two of the connecting members are fixed, so that at least one other of the connecting members is movable in a direction perpendicular to a surface direction of the leaf spring.

An objective lens is fixed to the connecting member corresponding to the movable side of the leaf spring mechanism, and the objective lens is driven by an actuator in a direction perpendicular to a surface direction of the leaf spring.

(Operation) With the above configuration, even if a distortion occurs in the connecting member during cooling after injection molding, the length and angle relationship of the leaf spring acting portion between the connecting members does not change, so that the influence of the distortion is reduced. Not reachable. Therefore, even when affected by the coefficient of thermal expansion at the time of cooling after injection molding, a leaf spring mechanism that can suppress non-linear movement characteristics in the bending direction, or the optical frequency without lowering the resonance frequency in the tracking direction An optical disk device capable of sufficiently securing a servo band required for device control is provided.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an optical pickup of an optical disk device using a leaf spring mechanism of the present invention as a focusing drive mechanism.
The figure is an exploded perspective view. Here, an objective lens 1 for recording and reproducing information on an optical disk (not shown)
Are two leaf springs 2a and 2b formed in a substantially isosceles triangular shape.
Are held by a lens holder 3 (connecting member) fixed to one vertex. Leaf spring fixing portions 4a, 4b (connecting members) are provided at the other apexes of the leaf springs 2a, 2b, and are integrally formed by injection molding similarly to the lens holder 3. In addition, leaf spring 2
a, 2b, the lens holder 3, and the leaf spring fixing portions 4a, 4b constitute a leaf spring mechanism 5. The leaf spring fixing portions 4a and 4b are provided with holes 21a and 21b formed in the rotating drum 7 rotatably provided with respect to the base 6, and bosses 22a and 22b formed in the leaf spring fixing portions 4a and 4b. Are arranged to fit. The leaf spring fixing portions 4a and 4b are adhered or pressed to the projections 8a and 8b provided on the rotating drum 7 so as to have a longitudinal direction opposite to the mounting portion of the leaf spring mechanism 5. The joining surface is formed so as to be perpendicular to the track direction (the rotation direction of the rotary drum 7).

The lens holder 3 is formed in a substantially cylindrical shape, and a focusing coil 9 also wound in a substantially cylindrical shape is provided here.
Are integrally molded. Also, the lens holder 3
A magnetic circuit 12 including a permanent magnet 10, a yoke 11a, and a yoke 11b, which is partially formed in a cylindrical shape, is inserted through the inside.
The permanent magnet 10 has the magnetization direction as the optical axis direction. Magnetic circuit
Reference numeral 12 is fixed near the tip of the rotary drum 7. here,
An optical path hole 13 provided at the tip of the rotary drum 7 corresponds to a hollow portion provided in the magnetic circuit 12 and the lens holder 3.

On the other hand, on the side surface of the rotary drum 7, two tracking coils 14 are provided at positions symmetrical with the rotation axis of the rotary drum 7.
a and 14b are fixed. The tracking coils 14a, 14b are wound in a direction perpendicular to the focusing coil 9, and pass through the middle yokes 16a, 16b constituting a part of two magnetic circuits 15a, 15b provided on the base 6 in a non-contact manner. It is like that. The magnetic circuits 15a and 15b are arranged in
a, 17b, permanent magnets 18a-18d, middle yokes 15a, 16b, permanent magnets
The upper yokes 17a, 17b and the middle yokes 16a, 16b are formed by joining two members at their respective intermediate portions. Permanent magnet 18
Both the magnets a to 18d and the permanent magnets 19a to 19d have the magnetization direction as the lamination direction and the directions are reversed. Also, the magnetic circuits 15a, 15b
Has an arc centered on the rotation axis of the rotary drum 7.

The interior of the rotating drum 7 is a space in which electric components, optical components, photoelectric conversion elements, and the like are arranged. The interior of the rotating drum 7 is connected to an external power supply (not shown) through a means such as a flexible substrate. You. These parts can be attached by removing the lower lid 7a. In addition, the shape of the rotary drum 7 includes an arc portion 30 and a protruding portion 31.
The protruding portion 31 is provided with the leaf spring units 2a and 2
It has a substantially triangular shape corresponding to the shape of b.

Further, the inertia moments of the tracking coils 14a and 14b are determined by the rotation drum 7 and all the components that are driven integrally with the rotation drum 7 (however, the tracking coil 14a
a, 14b) except for the total moment of inertia.

Here, the leaf spring mechanism 5 will be described in detail. FIG. 3 is a plan view showing the leaf spring 2 used for the leaf spring mechanism 5.
As shown in the drawing, the leaf spring 2 has a hole 40 and is formed in a substantially isosceles triangular shape, and has a shape in which a position corresponding to the injection molded part of the lens holder 3 protrudes. .
The resin molding is performed by injection molding at three locations indicated by oblique lines in FIG. 4, where the lens holder 3 and the leaf spring fixing portions 4a and 4b are formed. The portion where the resin is molded is a substantially isosceles triangular leaf spring 2
Corresponds to each vertex angle portion. At the time of injection molding, two leaf springs 2 are positioned (held) in parallel using a mold or the like.
Then, the above-described focusing coil 9 may be positioned at the same time, and then resin may be injected into the hollow portion of the mold to form the lens holder 3 and the leaf spring fixing portions 4a and 4b.
The leaf spring mechanism 5 thus completed is as shown in FIG. 5 and supports the movable body at one apex angle of the triangle, and the other two apex angles (here, both base angles) of the triangle are fixed to the fixed part. It is arranged to be.

The operation of the optical disk device having the above configuration will be described. When the objective lens 1 is driven in the focus direction of the optical disc, the energizing control of the focusing coil 9 is performed.
The Lorentz force generated by the influence of the magnetic flux received from the magnetic gap of the magnetic circuit 12 is used. At this time, the objective lens 1 can be moved substantially in parallel along its optical axis by the leaf spring mechanism 5. That is, the movement is performed in a direction perpendicular to the plane of the leaf spring 2. On the other hand, when the objective lens 1 is driven in the track direction of the optical disk, the tracking coils 14a, 14
The current control of b is performed, and the Lorentz force generated by the influence of the magnetic flux received from the magnetic gap of the magnetic circuits 15a and 15b is used. The rotary drum 7 on which the objective lens is mounted rotates around the central axis, and as a result, the objective lens 1 can be moved.

Looking at the leaf spring mechanism 5, two leaf spring fixing portions 4
a and 4b are connected only by a leaf spring, and the two leaf spring fixing portions 4a and 4b are substantially separated. Now, as shown in FIG. 4, if each side of the leaf spring 2 (2a, 2b) is A, B, C, the side C referred to here in the prior art described above is integrally molded. Therefore, the length of the side C changes due to the distortion, and the parallelism is lost due to the inevitable distortion of the other spring action portions, that is, the sides A and B. In the leaf spring mechanism 5 of the present invention, although the sides A, B, and C all correspond to the substantial spring action portions of the leaf springs 2a and 2b, distortion occurs during cooling after injection molding. Since the sides A, B, and C are not molded, there is no change in the length, and the angular relationship between the sides A, B, and C is constant, and the influence of the above-mentioned distortion is not exerted. Accordingly, the parallelism between the two leaf springs 2a and 2b is accurately maintained, and the bending characteristic of the leaf spring mechanism 5 does not become non-linear. Accordingly, a decrease in the resonance frequency of the optical disk device in the tracking direction is prevented, and a sufficient servo band required for controlling the optical disk device can be secured.

The present invention described above is not limited to the above embodiments. For example, using leaf springs 41 to 49 having a shape having various holes as shown in FIG. 6, even if the fixing members are substantially separated and injection molded as in the leaf spring fixing portions 4a and 4b, Exactly the same effect can be expected. Of course, the leaf spring mechanism may be formed by any combination of these leaf springs 41 to 49.

Further, the number of leaf springs used in the leaf spring mechanism of the present invention does not need to be two, and it is needless to say that three, four or even more leaf springs may be used. Further, the connecting members may be provided at three or more places. Further, the leaf spring mechanism is not limited to the above-described optical disk device, and can be applied to other devices.

[Effects of the Invention] As described above, according to the present invention, a leaf spring mechanism that can suppress non-linear movement characteristics in the bending direction even when affected by the coefficient of thermal expansion during cooling after injection molding. ,Also,
Provided is an optical disk device capable of sufficiently securing a servo band required for controlling the optical disk device without lowering a resonance frequency in a tracking direction.

[Brief description of the drawings]

1 and 2 are a perspective view and an exploded perspective view showing an optical pickup of an optical disk apparatus using a leaf spring mechanism of the present invention as a focusing mechanism, and FIGS. 3 and 4 are a plan view and an explanatory view of a leaf spring. FIG. 5 is a perspective view showing a leaf spring mechanism, FIG. 6 is a plan view showing a modification of a leaf spring constituting the leaf spring mechanism, and FIG. 7 is a perspective view showing an example of a conventional leaf spring mechanism. . DESCRIPTION OF SYMBOLS 1 ... Objective lens 2a, 2b, 2, 41-49 ... Leaf spring 3 ... Lens holder (connection member) 4a, 4b ... Leaf spring fixing part (connection member) 5 ... Leaf spring mechanism 40 ... Hole Department

Claims (4)

(57) [Claims] At least two leaf springs each having a hole and formed in a substantially triangular shape, and a connection formed at an apex of the leaf spring by injection molding and connecting the leaf springs substantially in parallel. A leaf spring mechanism, wherein two of the coupling members are fixed, and the other one of the coupling members is movable in a direction perpendicular to a surface direction of the leaf spring. . 2. The triangular shape is a substantially isosceles triangular shape,
The leaf spring mechanism according to claim 1, wherein the connecting member corresponding to the fixed side corresponds to both base corner portions of the isosceles triangle. 3. At least two leaf springs having holes,
A connection member formed by injection molding in at least three places around the hole of the leaf spring and connecting the leaf springs substantially in parallel with each other, wherein at least two of the connection members are fixed sides; A leaf spring mechanism, wherein at least one other of the connecting members is movable in a direction perpendicular to a surface direction of the leaf spring. 4. The leaf spring mechanism according to claim 1, wherein the objective lens is fixed to the connecting member corresponding to the movable side, and the objective lens is driven in a direction perpendicular to a plane direction of the leaf spring. An optical disk device comprising an actuator.