JPS62164235A - Optical system driver - Google Patents

Abstract

PURPOSE:To drive an optical system with high accuracy in a simple constitution by making use of the displacement of a piezoelectric element caused by its mechanical strains to perform a tracking action. CONSTITUTION:When the voltage is impressed to a piezoelectric element 101, the element 101 has a mechanical strain and is displaced in the direction A-A'. This displacement is transmitted to the direction (a) of a frame body part 102a via a head 103 attached to the tip part of the element 101. Then the displacement degree is amplified mechanically by the part 102a. In other words, a point of force produced by the head 103 is set closer to the fulcrum position than the position of hinge part 102d serving as an action point with the position of a hinge part 102e defined as a fulcrum. Thus the displacement degree of the element 101 is amplified by the action of levers and then transmitted to a support member 102. The end face of the part 102a is fixed to a base 111 and therefore an optical system holder attachment part 102b is displaced in the direction (b), e.g., the tracking direction with a shaft hole 102c defined as the center of the curvature radius. The displacement degree of the element 101 is amplified further at the part 102b because the action point is set closer to the hole 102c than an attachment part 102b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an optical system drive device, and particularly to an optical information recording/reproducing device such as an optical disk device, a magneto-optical disk device, or a digital audio device. This invention relates to an optical system drive device that focuses light onto an information recording medium.

(Prior Art) In general, in an optical information recording/reproducing device such as an optical disk device, in order to read information recorded in information bits (width 1 to 2 μm, length 1 to 3 μm) of an information recording medium, first, A light beam (usually a laser beam) is focused on a minute spot by an optical system such as an objective lens, and is irradiated onto an information bit. At this time, the reflected light or transmitted light from the information recording medium optically changes depending on the presence or absence of information. By detecting this change with a photodetector, a reproduced signal corresponding to the information bit can be obtained. In the optical information recording/reproducing apparatus described above, it is extremely important that the minute spot of the light beam always accurately scans the information pit row on the information recording medium. for that.

Autofocus is required to correct focal shifts due to warping of the information recording medium, and autotracking and kinging are required to correct irradiation position shifts due to eccentricity of the information recording medium.

As a means for realizing the autofocus function and the autotracking and tracking functions, a method is known in which the optical system is supported by a spring-like structure and the electromagnetic force generated by a magnetic circuit consisting of a coil and a magnetic member is utilized.

FIG. 4 is a perspective view showing a conventional optical system drive device having an autofocus function and an autotracker and kinger function. In this figure, 1.2 is F.

- A magnet and a yoke that constitute a magnetic circuit for casing, and 3.4 are a magnet and a yoke that constitute a magnetic circuit for tracking. Reference numeral 5 denotes an optical system holder on which an objective lens 6 is attached as an optical system, and coils 7 and 8 fixed to opposite sides of the optical system holder 5 are arranged in the magnetic circuits for focusing, tracking, and king, respectively. It is located in Reference numerals 9 and 10 denote support springs that hold the optical system holder 5 movably in the focusing direction, and 11 and 12 denote support springs that hold the optical system holder 5 movably in the tracking direction. are connected. This is a base on which the 14 magnets 1, 3, yokes 2, 4, optical system holder 5, support springs 9, 10, 11, 12, etc. are arranged.

In the device configured as described above, by applying a current to the coil 7.8, each magnet 1°3, yoke 2,
The interaction of the electromagnetic forces produced by the magnetic circuit consisting of 4 makes it possible to focus and track the objective lens 6 mounted on the optical system holder 5 via the respective support springs 9, 10, 11, 12.

(Problems to be Solved by the Invention) However, the above-mentioned leaf spring-shaped support spring 9.10.
11.12, each support spring 9.10.11.1 is used for tracking and focusing at high frequencies due to its characteristics.
2 has a problem in that highly accurate tracking and focusing cannot be performed due to the occurrence of sub-resonance.

On the other hand, in order to solve the above problem of sub-resonance, an apparatus in which an optical system is supported by a support member rotatably provided about a predetermined axis has been proposed in Japanese Patent Publication No. 30017/1983. However, in this device as well, the optical system is driven by electromagnetic force between a magnet and a coil, so the structure of the magnetic circuit etc. is complicated and the device tends to be large.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide an optical system driving device that can drive an optical system with high precision and a simple configuration.

(Means for Solving the Problems) As a means for solving the above-mentioned problems, the present invention provides an optical system drive device that includes a support member that is rotatably provided around a certain axis, and a support member that is rotatable around a certain axis. The gist includes: an optical system supported at a position apart from the axis so that its optical axis is substantially parallel to the axis; and a piezoelectric element that applies a driving force in the rotational direction to the support member. It is something to do.

(Example) Hereinafter, the present invention will be explained in detail with reference to an illustrated example.

FIG. 1 is an exploded configuration diagram showing an optical system driving device according to the present invention. In this figure, 101 is a laminated piezoelectric element, and the piezoelectric element 101 is constructed by laminating a ceramic 101b formed by printing and laminating extremely thin internal electrodes 101a on a thin green sheet (see Fig. 2). reference). IOlc is an insulator provided on the side surface between each ceramic 101b, and terminals 101d,
An external electrode 101f having a diameter 101e is provided. 102 is a linear support member that supports the optical system;
A piezoelectric element 101 is disposed within a frame part 102a formed on one side of the support member 102, and a head 1 is provided at the tip of the piezoelectric element 101.
03 is in line contact with the frame portion 102a. 104
is a cylindrical optical system holder, and the optical system holder 104
An objective lens 105 is installed as an optical system,
A focusing coil 106 is disposed on the outer circumferential surface, and the outer circumferential surface is coated with a tear-four resin to reduce sliding friction resistance. And optical system holder 10
The 4Fi support member 102 is provided with a cylindrical optical system holder mounting portion 102b formed at the other end so as to be slidable in the optical axis direction of the objective lens, GE 105. Reference numeral 107 denotes a bearing inserted into the shaft hole 102c of the support member 102 from above, and the bearing 107 is locked by a fixing plate 109 attached to the upper part of the amplification member 102 with screws 108. 110 is a bearing provided on the base 111;
0 into the shaft hole 102c of the support member 102 from below.

The support member 102 is rotatably supported by point contact with a bearing 107 . In addition, the end surface of the frame body part 1 (12a is connected to the base 111
It is fixed with screws 112 and 113.

114 is a cylindrical magnet placed on the base 111;
The optical system holder mounting portion 102b of the support member 1()2 is located within the magnet 114. 102d, 102e.

Reference numeral 102f denotes a rib portion formed on the frame portion 102a of the support member 102, respectively.

The optical system driving device according to the present invention is configured as described above, and first, when tracking is performed, the terminal 101d,
Piezoelectric element 101 via 101e and external electrode 101f
Apply voltage to. Then, each laminated ceramic 1
Mechanical strain occurs in 01b, causing a displacement in the A-A' force direction. This displacement is caused by the piezoelectric element 1 as shown in FIG.
01 through the head 103 provided at the tip of the frame body 10.
It is transmitted in the a direction of 2a. The transmitted displacement amount of the piezoelectric element 101 is mechanically amplified by the frame portion 102g. That is, with the position of the hinge part 102e as a fulcrum, the point of force exerted by the head 103 is closer to the fulcrum than the position of the hinge part 102d, which is the point of action, so the amount of displacement of the piezoelectric element 101 is amplified by the lever principle, and 102
can be conveyed to. At this time, the end surface of the frame portion 102a is
11, the optical system holder mounting portion 102b formed at one end of the support member 102 is displaced in the b direction (tracking direction) with the shaft hole 102e as the center of its radius of curvature. Here, since the aforementioned point of action (the position of the hinge part 102d) is closer to the shaft hole 102c than the mounting part 102b, the displacement transmitted from the piezoelectric element 101 due to the lever principle is further amplified at the mounting part 102b. . For example, if the amount of displacement transmitted from the piezoelectric element 101 to the frame portion 102a of the support member 102 is 10 to 20 μm, the amount of displacement at the optical system holder mounting portion 102b is approximately several hundred μm. Moreover, by turning off the voltage applied to the piezoelectric element 101, the support member 102 returns to its original state. Advantages of using the laminated piezoelectric element include that it can be made light, thin, short, and compact, has high electrical-mechanical energy conversion efficiency, consumes low power, and can be driven with high precision.

Next, when focusing is performed, the optical system holder is mounted due to magnetic interaction between the magnetic field generated by applying a current to the coil 106 provided on the outer peripheral surface of the optical system holder 104 and the magnetic field generated by the magnet 114. An optical system holder 104 slidably disposed in the portion 102b holds the objective lens 1.
05 in the optical axis direction. At this time, the optical system holder 10
The outer peripheral surface of 4 is coated with Teflon-based resin, and the inner peripheral surface of the optical system holder mounting portion 102b is also mirror-finished to reduce sliding resistance, allowing smooth focusing. be.

Further, although this embodiment is an example in which the present invention is applied to an optical system drive device of an optical disk device, it is clear that the present invention can also be applied to other optical devices such as a shape detection device, a laser processing machine, etc.

The above-described embodiment describes the case where only the objective lens is driven as an optical system, but it is also applicable to the case where the entire optical system including the light source etc. is driven.

(Effects of the Invention) As explained above, the optical system driving device according to the present invention performs tracking using the displacement caused by mechanical distortion of the piezoelectric element, and therefore can drive the optical system with high precision with a simple configuration. It can be carried out.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an exploded state of an optical system driving device according to the present invention, FIG. 2 is a cross-sectional view showing a laminated piezoelectric element, and FIG. 3 is a main part of the optical system driving device according to the present invention. FIG. 4 is a perspective view showing a conventional optical system driving device. 101... Piezoelectric element, 102... Support member, 102
a... Frame body part, 102b... Optical system holder mounting part,
102c... Shaft hole, 104... Optical system holder, 10
5...Objective lens, 106...Coil, 107,1
10...Bearing. 111... Base, 114... Magnet. Agent Patent Attorney Minoru Yamashita 2nd NAA, 'klol Figure 3 4 N C Injury 1 to f13-1?

Claims (1)

[Claims] a support member rotatably provided around a certain axis;
an optical system that is supported at a position apart from the axis of the support member so that its optical axis is substantially parallel to the axis; and a piezoelectric element that applies a driving force in the rotation direction to the support member. Drive device.