JPS62205540A - Optical system driving device - Google Patents

Abstract

PURPOSE:To obtain a movable part which is small in size and light in weight and to heighten sensitivity of operation by supporting and driving the optical system by bimorph elements. CONSTITUTION:To drive an objective 102 in the direction of focus, a voltage is applied to bimorph elements 105, 106, and these elements 105, 106 are bent and moved in the direction of optical axis A by displacement H1. Then, bimorph elements 103, 104 joined elastically by elastic members 107, 108 are also moved unitedly in the direction A, and the objective 102 attached to the tip is also moved in the direction of optical axis A by H1. In case of driving the lens 102 in the direction of tracking, voltage is applied to elements 103, 104, and the elements 103, 104 are bent and moved in the direction perpendicular to the optical axis A by displacement H2. Thereby, the lens 102 attached to the tip of elements 103, 104 is also moved in the direction perpendicular to the direction of optical axis A by a quantity H2. At this time, the optical axis A of the lens 102 does not fall by bending and displacement of elements 103, 104 provided parallel to each other in the direction of optical axis A.

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. The present invention relates to an optical W movement 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 drive, in order to read the information recorded on the information pins (1 to 2 μm, 1 to 3 μm in length) of the information recording medium,
First, a light beam (usually a Radhe beam) is focused on a minute spot by an optical system such as an objective lens, and is irradiated onto an information pit. 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 pit 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. To this end, autofocusing is required to correct focal shifts due to warpage of the information recording medium, and autotracking is 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 function, 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. 5 is a perspective view showing a conventional optical system drive device having an autofocus function and an autotracking function. In this figure, 1 and 2 are magnets and a yoke that constitute a magnetic circuit for focusing, and 3 and 4 are magnets 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 both opposing sides of the optical system holder 5 are arranged in the magnetic circuits for focusing and tracking, respectively. has been done. 9. 10 is a support spring that holds the optical system holder 5 movably in the focusing direction; 11 and 12 are support springs that hold the optical system holder 5 movably in the tracking direction;
are connected via. 14 are the magnets 1, 3, yokes 2, 4, optical system holder 5, support springs 9, 10, 11,
It has nine bases with 12 mags installed.

In the device configured as above, by applying a °C current to the coil 7.8, each magnet 1°3, yoke 2,
Focusing and tracking of the objective lens 6 attached to the optical system holder 5 via the respective support springs 9, 10, 11, and 12i can be performed by the interaction due to the electromagnetic force generated by the magnetic circuit consisting of 4.

(Problems to be Solved by the Invention) However, in the above-mentioned apparatus, the optical system holder 5, which is a movable part, includes support springs 9°10, 11, 12 that hold the optical system movably in the tracking and focusing directions. Since the coil 7 and the like for driving in the focus direction are integrally disposed, the weight of the optical system holder 5, that is, the movable part becomes heavy, resulting in a problem of poor operating sensitivity. In addition, when driving in the tracking and focusing directions, mechanical crosstalk occurs between the support members in both directions, causing the optical axis to tilt and the leaf spring-like support springs 9, 10, 11, and 12 torsion. However, there was a problem that high-precision tracking and focusing were not possible.

The present invention has been made in order to solve the above-mentioned problems of the conventional example, and it is an object of the present invention to provide an optical system drive device in which the operating sensitivity of the movable part is good and the optical system can be driven with high precision.

(Means for solving the problem) In order to solve the above problem, the present invention provides an optical system that
supported at one end of a bimorph element arranged substantially parallel to the optical axis direction of the optical system, and provided substantially perpendicular to the optical axis direction of the optical system at the other end of the opposed bimorph element. The main feature is nine configurations in which bimorph elements are joined together.

(Example) The present invention will be described below with reference to an illustrated example.7. ! +IB
Explain.

FIG. 1 is a schematic configuration diagram showing an optical system driving bag according to the present invention. In this figure, 101 is an optical system holder, and the optical system holder 101 includes an objective lens as an optical system;
e102 is installed.

Reference numerals 103 and 104 denote bimorph elements arranged parallel to and opposite to the direction of the optical axis A of the objective lens 102, and the optical system holder 101 is supported on the inner surface of one end side of the bimorph elements 103 and 104.

105 and 106 have one end thereof connected to the bimorph element 10.
3,104 is a bimorph element joined to the other end side,
The bimorph elements 105 and 106 are objective lenses, "102
They face perpendicularly to the direction of optical axis entry. 107,1
08 is an elastic member such as rubber, and the elastic member 107.1
08 is bimorph element 103, 105 and 104, 10
6. They are provided at the corners of the mutual joints as cushioning and reinforcing materials. 109 is a bimorph element 105, 10
6 is a base fixed to the other end side, and an outer frame 110 is further disposed on the outer surface of the base. 111 is a light source such as a semiconductor laser, 112 is a collimator lens that converts the laser light emitted from the light source 111 into parallel light, and 113 is the light source 111
This is a splitter that passes the radar light from the information recording medium 114 through the objective lens 102 and passes the reflected light from the information recording medium 114 to the light receiving element 115.

FIG. 2 shows the above-mentioned bimorph element 103 (bimorph elements 104, 105, and 106 are also the same), which includes two piezoelectric plates io3& that expand and contract in the longitudinal direction.

103b'e, 'J' Elastic plate 103e such as bronze plate
When one side is stretched out,
The other side contracts, resulting in a bending displacement as a whole.

The optical system driving device according to the present invention is configured as described above, and the laser beam emitted from the light source 111 is transmitted through the collimator lens
The information recording medium 114 is irradiated throughout 02. Then, the laser beam reflected on the information recording medium 114 enters the light receiving element 115 again via the objective lens 102 and the splitter 113, and information is reproduced. At this time, focusing and tracking of the objective lens 102 are performed as follows.

First, a case will be described in which the objective lens 102 is driven in the focus direction. As shown in Figure WIJ3, a voltage is applied to the bimorph elements 105 and 106 to bend and displace the bimorph elements 105 and 106 by a displacement ff1Ht in the same direction (eight directions of light Il'lh).

Then, the bimorph elements 103 and 104, which are elastically joined by the elastic members 107 and 108, are also displaced in the direction of the light 11+A, and the objective lens 102 attached to the tip thereof is also displaced in the direction of the optical axis A. Displaced by an amount H1.

Next, when driving the objective lens 102'i) in the racking direction, as shown in FIG.
3. Apply voltage to 104, bimorph element 103,1
04 by a displacement amount H2 in the same direction (perpendicular to the optical axis A). Therefore, the bimorph elements 103, 10
The objective lens 102 attached to the tip of 4 also has its optical axis A.
It is displaced by a displacement amount H2 in the direction perpendicular to the direction. At this time, the objective lens 102 is displaced parallel to the optical axis A direction due to the bending displacement of the bimorph elements 103 and 104 which are arranged parallel to each other with respect to the optical axis A direction, and the optical axis A of the objective lens 102 is
No collapse will occur.

In addition, although this embodiment is an example in which it is applied to an optical system drive device for optical disk drawing, it is applicable to a shape detection nail mounting machine, a radar processing machine, etc. 1.
It is obvious that it can also be applied to other optical instruments.

Although the above-mentioned embodiments have been described in the case where only the objective lens is driven as the optical system, 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 drive device according to the present invention has the following features:
By supporting and driving the optical system using a bimorph element, it is possible to reduce the size and weight of the moving parts and improve the operating sensitivity.Furthermore, it is possible to easily drive the optical system with high precision without tilting the optical axis. It can be done in configuration.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a schematic configuration diagram showing an optical system σ motion device according to the present invention, Fig. 2 is a side view showing a bimorph element of the same device, and Figs. 3 and 4 are the same. FIG. 5 is a side view showing the next state after displacing the Nonoimorph element of the device, and FIG. 5 is a perspective view showing the optical system driving device in the conventional example. 101... Optical system holder, 102... Objective lens,
103.104, 105.106... Bimorph element, 114... Information recording medium. Agent Patent Attorney Jo Taira Yamashita Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] An optical system is supported on one end of a bimorph element arranged substantially parallel to the optical axis direction of the optical system, and the other end of the opposed bimorph element is supported substantially parallel to the optical axis direction of the optical system. An optical system drive device made by joining vertically installed bimorph elements.