JPS63144431A - Optical system driving device - Google Patents

Abstract

PURPOSE:To lower the resonance acuteness of a primary resonance value to improve the frequency response and reduce an unnecessary rolling phenomenon by using a whisker impregnated with resin as the elastic member which supports a mobile member. CONSTITUTION:The whisker is impregnated with resin to obtain an elastic member 30. That is, the elastic member 30 used in an optical system driving device consists of the potassium titanate whisker impregnated with resin, and nylon 6, nylon 66, polyacetal, or the like is used as resin with which the whisker is impregnated. One end of the elastic member 30 constituted in this manner is stuck to the mobile member as a body to be driven and the other end is stuck to the base as a fixed material to support the body to be driven. For example, if this elastic member 30 is used in the part of a spring member 36, the peak value of the primary resonance value is reduced and a well-damped frequency characteristic is attained. Thus, the optical system driving device is obtained where the unnecessary rolling phenomenon is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical system drive device that is suitably used, for example, to drive an objective lens of an optical head in an optical information recording/reproducing device.

[Conventional technology]

Conventionally, optical information recording and reproducing apparatuses record information on the recording medium and/or reproduce information recorded on the recording medium by irradiating a spot of laser light onto the surface of the recording medium. has been put into practical use.

An example of such a device is an optical disk device. The optical disc, which is the recording medium on which information is reproduced by this optical disc device, has a width of about 1 to 2 μm and a length of about 1 to 2 μm.
An information track consisting of a row of information pits of about 3 μm is formed in a spiral shape or a concentric circle shape. When reproducing the information recorded as the information pit string, without rotating the optical disk, a laser beam is irradiated from the optical head in the form of a minute spot onto the information track of the optical disk, and the information pit string is scanned by the beam spot. let When the reflected or transmitted light of the light irradiated onto the optical disk surface is detected by a photodetector, the amount of light incident on the photodetector is determined depending on whether or not there is an information pit at the beam spot position. Optical properties change. In this way, a reproduced signal corresponding to the information pit string can be obtained.

In addition, in such an optical disk device, it is extremely important that the minute spot always accurately scan the information pit row on the recording medium. For this purpose, autofocusing that corrects a focus shift caused by warping of the recording medium and autotracking that corrects an irradiation position shift due to eccentricity of the recording medium, etc. are required. As a method to realize this auto 7 orcasing function and auto tracking function,
An objective lens driving device as shown in FIG. 6 has been considered. Incidentally, FIG. 6 is a perspective view showing a conventional objective lens driving device. In the conventional objective lens driving device 2 shown in FIG. 6, numeral 4 is a base made of a rigid body.

The base 4 is attached to, for example, an optical information recording/reproducing device (not shown) or the like in parallel to the yz plane as shown. In the vicinity of the four corners of the base 4, one ends of elastic members 6a to 6d, which are isotropic elastic bodies made of thin metal rods or the like, are each fixed as shown. The other ends of the elastic members 6 to 6d are respectively fixed to four ends of a movable member 10, which is a holder for holding the objective lens 8, as shown in the figure. Note that the elastic members 61 to 6d are arranged parallel to each other, as shown in the figure.

A focusing coil 12 is wound around the outer periphery of the side surface of the movable member 10 for driving the objective lens 8 in seven focusing directions (two directions).

Furthermore, at both ends of the movable member 10 in the y direction,
A tracking coil 14a for driving the objective lens 8 in the tracking direction (y direction).

14b is provided.

Further, the objective lens driving device 2 has a magnetic circuit 20 in which a magnet 18 is fixed to the yoke 16 of the rotor. The yoke part of the magnetic circuit 20 on the side to which the magnet 18 is fixed is arranged to be located in the gap between the base 4 and the focusing coil 12, and the yoke part on the side without the magnet 18 is arranged to be located in the gap between the movable member 10. It is arranged so as to be inserted into the opening 22s1 provided in the. Further, although not shown, a magnetic circuit similar to the magnetic circuit 20 is also arranged in the opening 22b so as to face the circuit 20.

In the objective lens driving device 2 described above, the objective lens 8 is driven using a magnetic field created by the magnet 18 and the yoke 16, and a tracking coil 12 and tracking, which is a current flowing in a direction perpendicular to the magnetic field. Coil 14a.

This is done by the electromagnetic force generated by the current flowing through 14b. As a result, the objective lens 8 can be driven in seven focusing directions (two directions) and the tracking direction (y direction).

The objective lens driving device 2 as described above has the following problems.

In other words, when the elastic members 6&~6d supporting the movable member 10 are made of metal rods, for example, the resonance sharpness (qo) at the lowest resonance frequency (fo) of the elastic member 6 is
) becomes high, deteriorating the response performance of the servo system. This is because the internal loss of the metal rod is small, making it difficult to damp resonance.

On the other hand, when a viscoelastic member made of a material such as PUM is used as the elastic member 6, it is possible to lower the resonance sharpness compared to the method using the metal rod. However, this method also has the following drawbacks.

[Problem that the invention seeks to solve]

That is, when a rubber material is used as a viscoelastic body, the resonance sharpness is determined by the viscosity of the rubber material, so when the rubber material hardens due to temperature changes, (mu) increases (qo).
It also becomes more expensive. As a result, the performance of the servo system deteriorates. Also, those whose viscosity changes little with temperature changes are
It generally has poor damping properties and is unsuitable for use as a support member. Furthermore, the im material has a phenomenon of aging due to changes over time, and there remains a problem in its reliability as a support means that needs to be used for a long period of time.

In addition, since the movable end of the support member made of a viscoelastic member such as a metal rod or rubber material is designed to move freely in all directions, it is possible to prevent slight imbalances in the driving force and the position of the center of gravity of the driven object. Due to a slight deviation from the center of the driving force, when the driven object vibrates, unnecessary four-coupled resonance occurs in the operating band, so-called rolling phenomenon occurs, and the optical axis of the objective lens moves while being tilted, which interferes with the performance of the sensor. This often results in

〔the purpose〕

The present invention has been made in view of the problems of the prior art described above, and its purpose is to provide an optical system with low resonance sharpness of the primary resonance value, good frequency response, and less unnecessary a-ring phenomenon. The purpose of the present invention is to provide a driving device.

[Means for solving problems]

According to the present invention, the above object is an optical system having a movable member holding an optical system, an elastic member having one end fixed to the movable member and the other end fixed to a fixed member, and means for driving the movable member. System driving device: This is achieved by an optical system driving device characterized in that the elastic member is made of whiskers impregnated with resin.

〔Example〕

Hereinafter, embodiments of the present invention will be described specifically and in detail based on the drawings.

FIG. 1 is a partial front view showing one embodiment of an elastic member used in an optical system driving device according to the present invention.

As shown in the figure, the elastic member 30 used in this embodiment is made of potassium titanate whiskers impregnated with resin. Examples of the resin to be impregnated into the whiskers include nylon 6 and nylon 66° polyacetal.

The optical system driving device according to the present invention has one end of the elastic member 30 configured as described above fixed to a movable member that is a driven body, and the other end fixed to a base that is a fixed object, thereby providing υ, Supports the driven body.

Hereinafter, the effect of the elastic member 30 of the present invention configured as described above as a spring will be explained.

FIG. 2 is a diagram for explaining the operating principle of the elastic member as a spring in this embodiment and the conventional example.

As shown in the figure, one end of the spring material 36 is fixed to the fixed wall 38, and the other end is fixed to a mass point 40 having a mass m. In this figure, as an example of the conventional example, when the spring member 36 is a metal rod, and assuming that the force applied to the mass point 40 is F, the equation of motion is as follows.

mx = −kg −ax−)−F −(1
) Here, k is the elastic constant of the spring material, and C is the viscosity coefficient of the spring material. Normally, the viscosity coefficient C of metal is c (1), so the peak value of the primary resonance value is a very high value (~3
0dB).

On the other hand, when the elastic member 30 shown in FIG. 1 is used as the spring member 36 as an example of this embodiment, the equation of motion is as follows.

mM=-kx-(e-)-e')x+F ・”(2
)C' is the viscosity coefficient of the resin, and since the internal loss of resin is larger than that of normal metals, e (c'(1), so c ((e + c') (1) Nasi,
The peak value of the -order resonance value can be lowered.

As a result, as shown in the solid line 42 in the graph of FIG.
The peak value of the next resonance value is small, and frequency characteristics with effective damping can be obtained. In the figure, the broken line 44 indicates the frequency characteristics obtained when only a thin metal rod is used as the support.

FIG. 4 is a perspective view showing an embodiment of the optical system driving device according to the present invention. Note that the same members as in FIG. 6 are given the same reference numerals.

In FIG. 4, elastic members 50a and 50b.

50e and 50d are made of metal whiskers impregnated with resin.Each elastic member 50a to 50d is arranged parallel to each other, one end is fixed to the movable member 0, and the other end is fixed to the base 4. The objective lens 8 and the movable member 10 are supported. The elastic members 50a to 50d are enabled to be energized.

In this optical system drive device, the focusing direction (2
By passing current through the axial direction) driving coil 12 and the tracking direction (y-axis direction) driving coils 14m and 14b, the objective lens 8 and the movable member 10 can be driven in the 7-orcasing direction and the tracking direction, respectively. .

Moreover, each of the four elastic members 50a to 50d.

The focusing direction driving coil and the tracking direction driving coil are connected to each other, and a current is applied to each of the driving coils through the elastic member 50.

In the above examples, the support used was a whisker of potassium titanate impregnated with a resin, but this is not limited to potassium titanate, and it is also possible to use whiskers of A (for example, ceramic) (metal or non-gold) impregnated with a resin. Anything is fine.

In addition, when a wire rod made of conductive metal whiskers impregnated with resin is used as a support, the support can also be used as a conductor for a coil for driving in the focus direction and track direction. In the case of a wire rod whose whiskers are impregnated with resin, the conducting wire 62 of the seven orcus direction and track direction drive coils may be wound around the circumference of a non-conductive wire rod 60, as shown in FIG. The conductor 62 is glued to the adhesive 64
a.

It is bonded to the υ wire 60 by 64b.

In addition to the embodiment shown in FIG. 5, the present invention may also be implemented by insert-molding a conductive metal wire together with the resin when impregnating the non-metallic whisker with resin, and using the metal wire as a conductive wire.

〔Effect of the invention〕

As described above in detail and specifically, the present invention uses a whisker impregnated with resin as the elastic member that supports the movable member, so the resonance sharpness of the -order resonance value is small, and the frequency It is possible to provide an optical system drive device with good response and less unnecessary rolling phenomenon.

[Brief explanation of the drawing]

Fig. 1 is a partial front view showing an embodiment of the elastic member used in the optical system drive device according to the present invention, Fig. 2 is a diagram for explaining the operating principle of the elastic member, and Fig. 3 is the frequency characteristic. 4 is a perspective view showing an embodiment of the optical system drive device according to the present invention, FIG. 5 is a partial front view showing another embodiment of the elastic member, and FIG. 6 is a conventional objective lens drive. FIG. 2 is a perspective view of the device. 4... Base, 8... Objective lens, 10... Movable member, 30... Elastic member. Agent Patent Attorney Jo Taira Yamashita Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In an optical system drive device having a movable member holding an optical system, an elastic member having one end fixed to the movable member and the other end fixed to a fixed member, and means for driving the movable member; An optical system driving device, wherein the elastic member is made of whiskers impregnated with resin. (2) The optical system driving device according to claim (1), wherein four elastic members are provided, and each elastic member is arranged parallel to each other.