JPS63119027A - Optical system driving device - Google Patents

Abstract

PURPOSE:To obtain the titled device low in resonance sharpness of a primary resonance value, capable of suppressing the rolling phenomenon of a driven part and to execute satisfactorily a frequency response by constituting an elastic member of a first single line and a second single line wound to the first single line. CONSTITUTION:Four supporting springs 46a-46d are sound by making coincident the winding direction to locate mutually on a diagonal line, for example, in the right screw direction, and making coincident the winding direction of the spring to locate on other diagonal line in the left screw direction. For such a reason, a rotation force 50 of a right rotation direction to occur with a center 48 of a moving member 10 as a rotation center is suppressed by left screw winding springs 46b and 46d, reversely, a rotation direction 52 of a left rotation direction is suppressed by right screw winding springs 46a and 46c and the rolling phenomenon with the center 48 of the moving member 10 as the rotation center can be suppressed. Thus, the optical type driving device can be obtained in which the resonance sharpness of the primary resonance value is small and a frequency response is satisfactory.

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.

[Prior Art] Conventionally, there has been an optical type in which a laser beam is irradiated onto the surface of an information recording medium in a spot shape to record information on the recording medium and/or to reproduce information recorded on the recording medium. Information recording and reproducing devices have been put into practical use.

An example of such a device is an optical disk device. Is this an optical disc? On an optical disk, which is a recording medium on which information is reproduced, an information track consisting of a row of information pits with a width of about 1 to 2 p-m and a length of about L to 3 JLm is formed in a spiral or concentric shape. . When reproducing the information recorded as the information bit string, the optical disk is not rotated, and the information track of the optical disk is irradiated with a laser beam from an optical head in the form of a minute slit, and the information bit string is scanned by the beam spot. When a photodetector detects the reflected light or transmitted light of the light irradiated onto the optical disk surface in this way, the optical difference of the light incident on the photodetector depends on whether or not there is an information bit at the beam spot position. Character changes. Thus,
A reproduced signal corresponding to the information bit string can be obtained.

Furthermore, in such an optical disk device, it is extremely important that the minute spot always accurately scan the information bit string 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 autofocusing function and autotracking function.

An objective lens driving device as shown in No. 7rA has been considered. Incidentally, FIG. 7 is a perspective view showing a conventional objective lens driving device.

In the conventional objective lens driving device 2 shown in FIG. 7, the number 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 support members 63 to 6d, which are isotropic viscoelastic bodies made of fine metal rods or the like, are each fixed as shown in the figure.

The other ends of the support members 6a to 6d are respectively fixed to four ends of a movable member 10, which is a holder that holds the objective lens 8, as shown in the figure.

As shown in the figure, the support members 6a to 6d are arranged in parallel to each other.

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

Furthermore, at both ends of the movable member IO in the y direction,
Tracking coils 14a and 14b are provided for moving the objective lens 8 in the tracking direction (y direction).

In addition, the objective lens driver fi1!12 is equipped with a U-shaped yoke 16.
It has a magnetic circuit 2o to which a magnet 18 is fixed. 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 as a movable member lo. It is arranged so as to be inserted into an opening 22a 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 method of driving the objective lens 8 is to use a magnetic field created by the magnet 18 and the yoke 16, and a current flowing in a direction perpendicular to the magnetic field, which is the focusing coil 12 and the tracking coil 14a.

This is done by electromagnetic force generated by the current flowing through 14b. This allows the objective lens 8 to be driven in the focusing direction (two directions) and the tracking direction (y direction).

The objective lens driving device aL2 as described above has the following problems.

That is, when the support members 6a to 6d that support the movable member 10 are made of metal rods, for example, the resonance sharpness (9°) at the lowest resonance frequency (fo) of the support member 6 becomes high, and the servo This deteriorates the response performance of the system because the internal loss of the metal rod is small and it is difficult to damp resonance.

On the other hand, when a viscoelastic member made of a material such as rubber is used for the support member 6, it is possible to lower the resonance sharpness compared to the method using the metal rod. but,
This method also has the following drawbacks.

[Problems to be Solved by the Invention] 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, etc. becomes higher (9°). As a result, the performance of the servo system deteriorates, and materials whose viscosity changes little with respect to temperature changes generally have poor damping characteristics and are unsuitable as support members. Furthermore, rubber materials tend to age due to changes over time, and as a support means that needs to be used for a long period of time, reliability remains a problem.

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, the driven object generates an unnecessary coupled resonance within the operating band during the operation, so-called rolling phenomenon, and the optical axis of the objective lens moves while being tilted, which interferes with the servo performance. This often occurs.

FIG. 8 is a graph showing the frequency characteristics of the objective lens when a rolling phenomenon actually occurs.

As shown in the figure, secondary co-torsion occurred near f, making the servo system unstable and often causing a phenomenon in which good signals could not be read.

[Purpose] The present invention has been made in view of the above-mentioned problems of the prior art.The purpose of the present invention is to reduce the sharpness of the primary co-confucian value, to suppress the rolling phenomenon of the driven part, and to reduce the frequency. The object of the present invention is to provide an optical system drive WJ'II device with good response.

[Means for Solving the Problems] According to the present invention, the above object includes a movable member holding an optical system, an elastic member having one end fixed to the movable member and the other end fixed to the fixed member; an optical system driving device having means for driving a movable member; characterized in that the elastic member is constituted by a first solid wire and a second solid wire wound around the first solid wire; This is achieved by an optical system drive.

[Example J] Hereinafter, an example according to 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 a support member used in an optical system driving device according to the present invention.

As shown, the support member 30 of the present invention has a diameter of approximately 0.1tsφ.
A single wire 34 made of a polymeric material and having a diameter of about 0.04 mm is wound around a phosphor bronze wire 32 of 0.04 mm. Although the winding interval may be spaced apart, in the embodiment shown in FIG. 1, the wire is wound closely. . Further, the support member 30 is impregnated with a viscoelastic liquid.

The optical system driving device according to the present invention fixes one end of the support member 30 configured as described above to a movable member, which is a driven body, and fixes the other end to a base, which is a fixed object. Supports the body.

Hereinafter, the effect of the support member configured as described above as a spring will be explained.

FIG. 2 is a diagram for explaining the operating principle of the support 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 the mass point 40 of the buy Fim. In this figure, as an example of a conventional example, when a spring material 42 made of, for example, a single wire of phosphor bronze is used as the spring material 36, the mass point 4
If the force applied to 0 is F, the equation of motion is as follows.

m'x = -kx - cx + F - (1) where k is the elastic constant of the spring material 42, and C is the viscosity coefficient of the spring material 42. Normally, the viscosity coefficient C of metal is c(1) Therefore, the peak value of the primary co-iso value is a very high value (~30 dB)
Take.

On the other hand, as an example of the present embodiment, when a spring material 42 made of a single wire of phosphor bronze impregnated with a viscoelastic material and a single wire of a polymeric material is wound on the outer periphery of the spring material 36 is used. *The equation is as follows.

m meal=-kx-(c+c'+c"+c"')x
+F − (2) Here, C′ is the viscosity coefficient of the sticky support, cl is the shear friction between the single wire of phosphor bronze wire and the single wire made of polymer material,
Alternatively, when single wires of polymeric material are tightly wound, the viscosity coefficient is due to the effect of adding the shear friction between the strands of polymeric material.

C″′ is the viscosity constant of the FJL line of the polymer material. Since c< (c+c′ +c”)<1,
The peak value of the -order co-torsion value can be lowered. (~15
dB) Next, the effect of the support member of the present invention on the rolling phenomenon of the driven body will be explained.

3(a) and 3(b) are diagrams showing the rolling phenomenon of the movable member according to the embodiment of the present invention, in which FIG. 3(a) is a plan view of the movable member 10, and FIG. 3(b) is the same. It is a figure which looked at figure (a) from A direction.

As shown in FIG. 3(b), four support springs 46a to 46
d is such that the winding directions of the springs located diagonally with each other match, for example, the right-hand thread direction, and the winding direction of the other diagonal spring matches the left-hand thread direction. By doing this, the rotational force 50 in the right rotation direction generated with the center 48 of the movable member IO as the rotation center is transferred to the left helical spring 46.
b.

46d, and conversely the rotational force 52 in the counterclockwise rotation direction
is held down by the right-handed spiral springs 46a and 46c, and can suppress the occurrence of a rolling phenomenon about the center 48 of the movable member 1O. As a result, ideal frequency characteristics as shown in the solid line graph in FIG. 4 are obtained. In FIG. 0, the broken line shows the frequency characteristics obtained when a single metal wire is used as the support member.

Further, the four support springs 46a to 48d are connected to the focusing coil and the tracking coil, respectively.
It also plays the role of a conductor.

Furthermore, the four support springs 46 may be made of a non-conductive material such as a polymer material. In this case, the frequency characteristics of the movable member 10 will be better with better damping than with metal support springs. Show characteristics.

tsS diagram and FIG. 6 are partial front views showing other embodiments of the support spring.

In FIG. 5, the first single wire 60 is a metal wire in the embodiment shown in FIG. Further, ceramic whiskers may be composited into a polymer material, or a non-conductive member made only of polymers may be used.In the embodiment shown in FIG. 1, the second single wire 62 is made of a polymer material. Although it was a single wire, even if it is a metal wire such as phosphor bronze, it may be a conductive member made of a composite of metal wire, Iscar, or carbon fiber in a polymer material, or The support member 66 may be a non-conductive member composed of ceramic whiskers, and the viscoelastic body 64 may or may not be impregnated. Either one of the first wire and the second single wire 62 may be made of a conductive single wire.

In this way, by selecting the materials of the first single wire 60 and the second single wire 62, and by selecting the pitch of the winding wires, a support spring having desired elastic constants and viscous constants can be constructed. I can do it.

FIG. 6 shows that both the first single wire 60 and the second single wire 62 are
A conducting wire 68 for a focusing or tracking coil is wound around a support member 66, showing an example in which a non-conductive single wire made of polymeric material is used. The conductive wire 68 is bonded to the support member 66 with adhesives 70a and 70b. The viscoelastic body may or may not be impregnated into the wire spring.
By using the conductive wire 68 as a guide, breakage of the conductive wire 68 can be prevented.

[Effects of the Invention] As described above in detail and specifically, the present invention provides a support member for a movable member which is a driven body, and a second single wire further attached to the first single wire.
Since the support spring is used with a single wire wrapped around it, the resonance sharpness of the primary resonance value is small.

Also, the optical system part can suppress the rolling phenomenon of the driven part and has a good frequency response! An Il device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a partial front view showing one embodiment of the support 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 support member, and FIG. 3(a) and (b)
is a diagram showing the rolling phenomenon of the movable member, FIG. 4 is a graph showing frequency characteristics, FIGS. 5 and 6 are partial front views showing other embodiments of the support member, and FIG. 7 is a conventional objective lens drive. FIG. 8, a perspective view of the device, is a graph showing frequency characteristics. 2... Objective lens drive device 4... Base 8... Objective lens 10... Movable member 30... Support spring Figure 1 Figure 2 Figure 3 [S M mantissa (H2) 5th Figure @ Figure 6 Figure 7 Figure 8 "Slope (KHz) Procedural Amendment January 1988 2111 Commissioner of the Patent Office Kuro 1) Akio Yu 1, Indication of Case Patent Application No. 1988-264036 2, Invention Name: Optical system drive device 3, person making the amendment Relationship to the case Patent applicant name: Canon Electronics Co., Ltd. 4, agent address: Mori Building, 40 Toranomon, 5-13-1 Toranomon, Minato-ku, Tokyo Details of the invention in the specification Explanation column 6, Contents of amendment (1) "...φ-Cx+..." on page 9, line 18 of the specification
・" is corrected to "...-chi+...".

Claims (3)

[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; The elastic member is comprised of a first solid wire and a second solid wire wound around the first solid wire,
Optical system drive device. (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. (3) The second single wire is wound in the same direction as the first single wire located diagonally to each other, and the direction in which the second single wire is wound around the other first single wire located on the other diagonal is opposite. An optical system driving device according to claim (2), characterized in that: