JPS63311633A - Optical system driver - Google Patents

Abstract

PURPOSE:To prevent the production of an eddy current in an optical system support and sub-resonance at drive by allowing the optical system support to be connected by a connection member having a high electric resistivity and high rigidity. CONSTITUTION:A resin using an epoxy group resin including SiO2 as the major component is used as the connection member 37 fixed to a notch 36. The resin is a resin having a high rigidity and useful to increase the rigidity in the notch 36. Moreover, the resin has a high resistivity to prevent the production of an eddy current in the notch 36. Since the deterioration in the rigidity in the notch 36 is suppressed while the production of the eddy current is prevented to the objective lens support 21, the objective lens support 21 is made of a conductive material with a low resistivity such as aluminum and the thickness of the support 21 is made thin. Thus, the drive sensitivity of the objective lens support 21 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical system drive device used, for example, in an optical head device.

(Prior Art) Conventionally, in order to record information on an information recording carrier such as an optical disk or to reproduce recorded information, a light beam emitted from a light source is narrowed down to a minute spot with a diameter of about 1 μI, and the light beam is focused on the information recording carrier. An information recording/reproducing device that emits light onto a recording surface is often used. Such recording and reproducing devices usually include focusing control to correct out-of-focus caused by surface wobbling of the information recording carrier, and correction of positional deviation of the light beam spot caused by eccentricity of the information recording carrier. A drive device is provided to perform tracking control for the purpose of the vehicle.

FIG. 3 shows an assembled perspective view of a conventional optical system drive device and will be described below. As shown in the figure, the objective lens holder 6 is inserted through a bearing 4 into a support shaft 16 that is fixed to a base 13 by press fitting or the like.

The objective lens 2 is attached to one end of the objective lens holder 6, and a balance weight 5 having approximately the same weight as the objective lens 2 is fixed to the other end. Further, a neutral point holding member 14 is provided below the weight 5, and the holding member 14 and the weight 5 are connected by an elastic member 17 made of silicone rubber or the like. The elastic member 17 can rotate or move up and down within the elastic range of the elastic member 17. A focusing coil 7 is wound around the outer periphery of the objective lens holder 6, and a tracking coil 8 is attached on top of this focusing coil 7.

Permanent magnets 9a and 9b are provided near the outer periphery of the objective lens holder 6 so as to face the focusing coil 7 and the tracking coil 8.
a, 9b are inner yoke parts ioa, 1 fixed to the base 12;
0b and the outer yoke portion 11a.

11b. The base 12 is made of a magnetic material, and the base 12 and the inner and outer yoke parts 10a,
10b, lla, and llb collectively form a yoke 3. Therefore, a magnetic field is formed in the gap between the inner yoke parts 10a, 10b and the outer yoke parts 11a, llb. By passing current through the focusing coil 7 or the tracking coil 8 of the objective lens holder 6, an electromagnetic force is generated, and the objective lens holder 6 is moved toward the support shaft 1.
It can slide vertically around 6 or rotate horizontally. At this time, the neutral point holding member 14 acts to return the objective lens holder 6 to the neutral position.

(Problem to be Solved by the Invention) However, in the conventional optical system drive device configured as described above, when the objective lens holder 6 is made of a conductor such as aluminum, a current is applied to the focusing coil 7. When the objective lens holder 6 is moved up and down by flowing the current, a concentric eddy current is generated inside the objective lens holder 6. Since this eddy current flows in a direction perpendicular to the magnetic flux generated inside the objective lens holder 6, the yoke 13
There is a risk that an electromotive force will be generated within the magnetic field in the gap, and the electromotive force obtained by passing a current through the focusing coil 7 will be canceled out.

For this reason, conventionally, slit-shaped notches 15 have been formed at required locations on the objective lens holder 6 in order to prevent the generation of eddy currents as described above.

However, when such a notch 15 is provided, the rigidity of the notch 15 of the objective lens holder 6 decreases, which causes the disadvantage that it resonates with the vibration frequency accompanying the vertical movement of the objective lens holder 6. was occurring. Such resonance significantly deteriorates the servo characteristics of the device.

To solve this problem, there have conventionally been examples in which the thin outer peripheral portion of the objective lens holder 6 has been thickened to increase rigidity, but the permanent magnet 9a described above.

9b and the inner yoke portions 10a, 10b, it becomes necessary to make the gap portions large, and in this case,
As the magnetic force density formed within the gap decreases and the weight of the objective lens holder 6 increases, the driving sensitivity of the objective lens holder 6 in the vertical and horizontal directions is significantly reduced.

In addition, as another method for solving the above-mentioned disadvantage, it is possible to form the objective lens holder 6 from a synthetic resin so that the above-mentioned notch is not provided. In order to maintain a high-order frequency of 20 kHz or more, the thin outer peripheral part of the objective lens holder 6 must be made significantly thicker, as in the above-mentioned solution method, which leads to a decrease in drive sensitivity, as described above. Put it away. Further, the objective lens holder 6 made of such a synthetic resin also has a problem in terms of processing accuracy.

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, an optical system drive device of the present invention includes an optical system holder supported movably in at least one direction, and an optical system holder supported movably in at least one direction. In an optical system drive device that includes a coil fixed to a holder and a means for generating a magnetic field across the coil, and moves the optical system holder by energizing the coil, the optical system holder comprises: It is characterized by comprising a conductive member forming the outer circumferential portion and having voids provided at required locations, and a connecting member having high rigidity and high electrical resistivity that connects the conductive members on both sides of the void. shall be.

(Function) In the optical system driving device of the present invention configured as described above, the optical system holder of this device has a configuration in which the optical system holder has a high electrical resistivity and is connected by a connecting member having high rigidity. Therefore, generation of eddy current in the holder can be prevented, and the rigidity of the holder as a whole does not decrease.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing an embodiment of an optical system driving device according to the present invention, and FIG. 2 is an enlarged perspective view of the main part of FIG.

In FIGS. 1 and 2, the objective lens holder 21 is slidably and rotatably inserted through a bearing 23 onto a support shaft 34 which is fixed to a base 32 by press fitting or the like. An objective lens 20 is attached to one end of this objective lens holder 21 via a lens barrel section 22, and a balance weight 2 having approximately the same weight as the objective lens 20 is attached to the other end.
4 is fixed. Further, below the weight 24, a neutral point holding member 35 having an S-shaped cross section is provided.

The neutral point holding member 35 has a lower end fixed to the FJS stand 32 via a positioning bin (not shown) attached to the base 32, and an upper end fixed to the weight 24 fixed to the objective lens holder 21. is fixed at the bottom edge of the Therefore, this neutral point holding member 35 acts to return the objective lens holder 21 to the neutral position when the objective lens 21 slides and rotates about the support shaft 34 with respect to the base 32. The neutral point holding member 35 can be made of silicone rubber or the like in order to have elasticity.

A focusing coil 2 is provided on the outer periphery of the objective lens holder 21.
5 is wound, and this focusing coil 2 is further wound.
A tracking coil 26 wound in a rectangular or elliptical shape is attached below the coil 5 . Moreover, the objective lens holder 2
1 is made of a conductor, so when the objective lens holder 21 moves up and down when a current is passed through the focusing coil 25, a reverse driving force is generated due to eddy current. A slit-like notch 36 is provided in the thin circular part forming the outer periphery of the 21, and this notch 36 is filled with an insulator or a low conductive expanded material.
A connecting member 3 made of a resin containing 5iO1 fine particles in an epoxy resin as a resin with low shrinkage and high rigidity.
7 is embedded and hardened so that it does not protrude into the inner and outer circumferential portions, thereby fixing it.

The base 32 has two arc-shaped focusing permanent magnets 28a and 28b formed so as to be uniformly close to the outer periphery of the objective lens holder 2, and two arc-shaped focusing permanent magnets 28a and 28b. Arc-shaped tracking permanent magnets 29a, 29b attached below each, and these permanent magnets 28a, 28b.

Outer yoke parts 31a and 31b, each of which has a combination of 29a and 29b fixedly attached to the inner surface thereof, and an inner yoke part 30a, which has at least an arcuate outer periphery and has a certain gap with respect to each of the outer yoke parts 31a and 31b.

30b, and the entire yoke 33 is integrally molded. In the gaps between the permanent magnets 28a, 28b of the yoke 33 and the inner yoke parts 30a, 30b, the outer peripheral part of the objective lens holder 21 is slidably rotatable about the support shaft 34. It is inserted. Therefore, in the yoke 33, the permanent magnets 28a, 2
Between 9a and inner yoke 3Oa, and permanent magnets 28b and 29b
A magnetic field is generated between the inner yoke 30b and the focusing coil 25 or the tracking coil 26 of the objective lens holder 21, thereby causing the objective lens holder 21 to move vertically or horizontally around the support shaft 34. It can be rotated. Thus, by passing a current in accordance with the focus error signal or tracking error signal through the coil 25 or 26, focus drive control or tracking drive control of the objective lens 20 can be performed.

The cut portion 36 will be described in more detail below. As described above, the connecting member 37 fixed to the notch 36 is made of a resin whose main component is an epoxy resin containing the aforementioned StO.

Table 1 below shows the properties of this resin.

As shown in this table, the resin is a highly rigid resin and is useful for improving the rigidity of the cut portion 36. Furthermore, the resin has a high resistivity and can prevent the generation of eddy current in the cut portion 36. In this way, the objective lens holder 21 in this embodiment prevents the generation of eddy current and suppresses a decrease in rigidity at the notch 36. It is possible to make the holding body 21 from a material such as aluminum, and to make the wall thickness of the holding body 21 thinner than that of the conventional one. By doing so, the weight of the objective lens holder 21 can be reduced, and the weight of the objective lens holder 21 can be reduced.
drive sensitivity increases.

However, the objective lens holder 21 is not limited to the above-mentioned aluminum;
It can be formed from a conductive material of about Ωm.

Note that the optical system driving device of the present invention is not limited to the embodiments described above, but can also be applied to an optical system driving device that supports an optical system holder using, for example, a parallel leaf spring. That is,
The present invention is not limited to the means for supporting the optical system holder.

In addition, in the present invention, resin is embedded in the cut portion and hardened.
A plate formed to match the shape of the notch may be bonded, but in this case, the rigidity will be slightly lower than when it is embedded and hardened.

(Effects of the Invention) As explained above, in the optical system driving device of the present invention, the optical system holder of this device has a configuration in which the optical system holder has a high electrical resistivity and is connected by a connecting member having high rigidity. Therefore, generation of eddy current in the holder can be prevented, and the rigidity of the holder as a whole does not decrease.

Therefore, in the optical system holder, generation of eddy current is prevented as described above, and sub-resonance is prevented from occurring when the holder is driven, so the optical system drive device has excellent servo characteristics. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an optical system driving device according to the present invention, FIG. 2 is a perspective view of the main part shown in FIG. 1, that is, an optical system holder, and FIG. 3 is a perspective view of a conventional optical system drive device. FIG. 3 is an exploded perspective view of the drive device. 21... Objective lens holder, 36... Notch, 3
7...Connection member.

Claims (2)

[Claims] (1) An optical system holder supported movably in at least one direction, a coil fixed to the optical system holder, and means for generating a magnetic field across the coil, and the coil is energized. In the optical system driving device that moves the optical system holder by:
A conductive member forming the outer periphery and having voids at required locations, and a connecting member having high rigidity and high electrical resistivity that connects the conductive members on both sides of the void. optical system drive device. (2) The optical system driving device according to claim 1, wherein the connecting member is made of a resin containing an epoxy resin as a main component and SiO2 fine particles.