JPH0431818A - Displacing device - Google Patents

Abstract

PURPOSE:To simplify the constitution of a displacing device and to drive the device with a high frequency by constituting a displacement enlarging mechanism by arranging plural blocks having a rectangular shape in a line and, at the same time, by using piezo-electric actuators connected in series. CONSTITUTION:A displacement enlarging mechanism 10 has rectangular block sections B1-B3 arranged in a line, force applying section C1 and C2, and stress concentrated sections D1-D4 and the mechanism 10 and laminated type piezo-electric actuators 13 and 15 are fixed to a supporting body 50. When, for example, reverse tensile forces are applied to the sections C1 and C, the blocks B1 and B3 are respectively turned clockwise and counterclockwise and the whole body of the mechanism 10 is deformed to an arch shape bent downward. Accordingly, the displacement of the sections C1 and C2 can be enlarged in the direction perpendicular to the displacing direction by utilizing the arch-like deformation. Therefore, the constitution of this displacement device becomes simpler and, since the laminated type piezo-electric actuators are drive in a state where they are connected in series, high-frequency displacement becomes possible.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a displacement device.

[Prior Art] A laminated piezoelectric actuator, which is known as an electromagnetic actuator that has an accurate response and can be driven at high speed, has a small amount of displacement, so it is necessary to increase the amount of displacement depending on the purpose of use.

For example, in an optical scanning device, it is possible to displace the light source and lens in synchronization with optical scanning in order to eliminate field curvature of the imaging optical system, which causes fluctuations in the diameter of the optical spot on the scanned surface. This is known, and recently it has been proposed to remove or reduce field curvature by displacing a cylinder lens located between a light source and a light deflection device in the optical axis direction. The amount of displacement of a cylinder lens, etc. required to correct such field curvature is usually several hundred μm, but the amount of displacement of a laminated piezoelectric actuator is usually about several tens of μm, and the displacement is several to several tens of times larger. Expansion will be necessary.

Also, the frequency of displacement of the cylinder lens etc. mentioned above is several KHz.
and high frequency. Since the multilayer piezoelectric actuator has a capacitive load, if the time constant of the electrical system including the drive circuit is large, the response of the multilayer piezoelectric actuator will no longer follow the drive frequency as the frequency of the drive voltage increases.

[Problems to be Solved by the Invention] Various displacement amplifying mechanisms are known and have been proposed, but many of them have complex configurations.

The present invention aims to provide a novel displacement device that uses a laminated piezoelectric actuator as a displacement source, has a simple configuration of a displacement magnification mechanism, and responds well to high-frequency driving.

[Means to solve the problem] The present invention will be explained below.

The displacement device of the present invention includes "a displacement magnification mechanism, an even number of laminated piezoelectric actuators, and a drive circuit."

The ``displacement magnification mechanism'' has ``a plurality of rectangular block sections arranged in a straight line, and a force acting section for receiving deformation force at both ends of the block section arrangement in the longitudinal direction, and between each block section. The block part and the force acting part are connected by a stress concentrating part and the whole is integrally formed, and when a pair of deforming forces in opposite directions are applied to the force acting part in the longitudinal direction, the stress concentrating part The position of each stress concentration part is determined so that the entire part deforms in an arched shape due to the deformation of the part, and the displacement of both ends due to the action of a pair of deforming forces is expanded as the amplitude of the deformation of the part. .

An even number of "stacked piezoelectric actuators" are arranged at both ends of the displacement magnification mechanism, and one is placed at each pair of force application parts.
Apply a pair of deforming forces.

The "drive circuit" drives the laminated piezoelectric actuator.

The even number of laminated piezoelectric actuators are connected in series.

[Operation] FIG. 2(A) shows an example of a displacement magnification mechanism used in the displacement device of the present invention.

In this example, the displacement magnification mechanism consists of three block parts Bl to B3.
, force acting portions C1 and C2, and stress concentration portion DI-04.

The block parts 81 to B3 are rectangular and linearly arranged,
Furthermore, force acting portions C1 and C2 are provided at both ends of the array in the longitudinal direction.
are in place.

These block portions 81 to B3 and force acting portions CI and C2 are connected to each other by stress concentration portions D1 to D4.

These block portions B1 to B3, force acting portions CI and C2, and stress concentration portions D1 to D4 are all integrally constructed of a single material. Since the displacement is expanded by deforming the stress concentration part as explained below, the material used for the displacement expansion device is such that the deformation of the stress concentration part required for displacement expansion is realized as elastic deformation.

Stress concentration parts DI, D4 and D2. The formation position differs from D3 in the width direction of the block portion, that is, in the vertical direction in FIG. 1(A). Therefore, if forces in opposite directions are applied to the force acting parts in the longitudinal direction of the displacement magnifying device, the block part B
Couples in opposite directions will act on l and B3.

For example, if the force in the opposite direction is a tensile force, Figure 1 (B
), the block portion Bl rotates clockwise, the block portion B3 rotates counterclockwise, and the entire displacement magnifying device deforms into a downward arcuate shape as shown in the figure.

Conversely, when a pair of compressive forces is applied to the force applying portions C1 and C2, the deformation becomes an upward arcuate shape as shown in FIG. 1(C).

Therefore, by utilizing this arched deformation, the displacement of the force applying portion can be expanded in a direction perpendicular to this displacement.

In the example shown in FIG. 1, there are three block portions, but the displacement magnification mechanism is not limited to this, and may have two block portions, or may have four or more block portions. However, in order to obtain linear motion, it is desirable that the number of block parts be an odd number, and if the moving object is placed directly in the center, the number of block parts will be an even number.

Next, the magnification rate of displacement will be explained based on the example shown in FIG.

It is clear that the increased displacement in the example described above is caused by the rotation of the block parts B1 and B3 in opposite directions.

Therefore, as shown in Fig. 3 (A), the block part B1 is set, its length is a, and the distance between the stress concentration parts Di and D2 in the width direction of the block part is b, and as shown in Fig. 3 (B). As shown, the block portion B1 is considered as a rod-shaped body whose both ends are restrained on the X and Y axes, respectively.

The state where no force is acting on the force acting part is denoted by code B1o (second
(corresponding to the state in Figure (A)), and the state when the displacement amplifying device is deformed in an upward arched manner as shown in Figure 2 (C) due to the action of the compressive force is represented by the symbol B11, and due to this deformation, X,
Let the displacement on the Y axis be u, , ua.

In this case, the following relationship clearly holds.

a2+ b2= (a-u,)2+ (b+uy)2=
a2+b2+ux”+u,”-2au,l+2buyU
Considering that tuy is a minute amount compared to a and b,
Ignoring the square of uxluy with respect to other terms, the following relationship is obtained.

2(au, -buy)=0 From this, it can be seen that the displacement expansion rate (Hu, /u,) is (a/b).

The second case when a=9.0mm and b=1.5mm
Figure 3 (C) shows the results of simulating the driving frequency characteristics of the expanded displacement amount of the displacement magnifying device shown in the figure using the finite element method.
Shown below. A laminated piezoelectric actuator was used as the driving source, that is, the laminated piezoelectric actuator that applies displacement to the force application portions at both ends of the displacement magnifying device. The amount of displacement of this laminated piezoelectric actuator is as shown in the figure, from frequency O to 3
It is stable at approximately 1101L up to 000Hz.

The enlarged displacement amount uy when the frequency is ○ is 51.3 μm. On the other hand, the theoretically determined expansion ratio (a/b) is 9.0/1
．． 56, and the displacement U of the laminated piezoelectric actuator is
When using =9.3, the theoretical expansion displacement amount is 55.8μ
m, which agrees well with the simulation results.

Furthermore, for a driving frequency of 3000 Hz, the theoretical value is 61 μm for the expanded displacement amount according to the simulation.
At 0 μm, the two coincide extremely well. This means that the displacement magnifying mechanism in the displacement device of the present invention can be easily designed.

In addition, in the displacement device of the present invention, an even number of laminated piezoelectric actuators that apply a pair of deforming forces to the displacement amplification mechanism as described above are arranged in the same number at both ends of the displacement amplification mechanism. The stacked piezoelectric actuators are connected in series and driven, so the overall capacitance is small.

[Example] Specific examples will be described below.

The displacement device of the present invention was used to correct field curvature in a known optical scanning device as shown in FIG.

In Fig. 4, the parallel light beam from the light source device 1 composed of the semiconductor laser LD and the collimating lens CL is shaped into a beam shape by the aperture 8, and then is powered only in the direction corresponding to the sub-scanning (direction perpendicular to the drawing). The cylinder lens 2A forms an image in the vicinity of the deflection reflection surface 4 of the rotating polygon mirror 3 as a long line image in the main scanning direction. The light beam reflected by the deflection reflecting surface 4 is deflected by the rotation of the rotating polygon mirror 3, enters an fθ lens constituted by lenses 5 and 6, and is imaged as a light spot on the scanned surface 7 by the action of the fθ lens. The surface to be scanned 7 is then optically scanned.

Although the FE lens has very well corrected field curvature in the main scanning direction, it has field curvature in the sub-scanning direction as shown in FIG. 5(A).

At this time, if the cylinder lens 2A is displaced along a sine curve as shown in FIG. 5(B), the curvature of field in the sub-scanning direction can be reduced as shown in FIG. 5(C).

Note that in FIG. 5(B), β is the imaging magnification of the fθ lens in the sub-scanning direction.

The sine curve in Fig. 5(B) can be expressed as 0,1322 cos (e + Q, 5033) mm, where the deflection angle of the deflected light beam is θ, and its frequency is 2.8K from the optical scanning speed.
Hz.

Therefore, by making the cylinder lens 2A perform a simple harmonic motion with a frequency of 2.8 KHz and an amplitude of 264 μm, the curvature of field in the sub-scanning direction can be improved as shown in FIG. 5(C).

In order to realize this simple harmonic motion, a displacement device as shown in FIG. 1 was used.

Reference numeral 10 designates a displacement magnification mechanism similar to that described with reference to FIGS. 1 and 2. The displacement magnifying mechanism 10 has three block parts, and the cylinder lens 2A is fixed to the central block part. The magnification factor of this displacement magnification mechanism is 12 times.

Reference numeral 13.15 indicates a piezoelectric actuator.

These piezoelectric actuators 13 and 15 are all laminated piezoelectric actuators with a displacement of approximately 10 μm, and achieve a total displacement of 20 μm.

As shown in Fig. 1 (B), a laminated piezoelectric actuator 1
3.15 are connected in series and driven by a drive circuit 16.

displacement magnification mechanism 10, laminated piezoelectric actuator 13,
15 is fixed to a bifurcated support 50 as shown in FIG. 1(A).

The laminated piezoelectric actuator 13.15 is driven by the drive circuit 16 at a frequency of 2.8 KHz in synchronization with optical scanning, and the cylinder lens 2A is moved in the optical axis direction with an amplitude of approximately 240μ.
It was possible to perform simple harmonic vibration at m, and to achieve correction of field curvature in the sub-scanning direction similar to that shown in FIG. 5(C).

Since the laminated piezoelectric actuators 13 and 15 are connected in series and driven, the capacitance of the drive source is 1/2 of that when used alone, and the time constant is significantly reduced, so it is possible to drive at a high frequency of 2.8 KHz. Despite this, the displacement of the laminated piezoelectric cut unit 13, 15 followed the drive well.

[Effects of the Invention] As described above, according to the present invention, a novel displacement device can be provided. This device has an extremely simple configuration as described above, and therefore can be manufactured at low cost. Furthermore, since stacked piezoelectric actuators are connected in series and driven, displacement of Takaoka wave number is possible.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining one embodiment of the displacement device of the present invention, FIGS. 2 and 3 are diagrams for explaining the displacement magnifying mechanism, and FIG. 4 is a diagram for explaining the displacement device of the embodiment. FIG. 5 is a diagram for explaining the optical scanning device used, and FIG. 5 is a diagram for explaining the effects of the embodiment. io, , displacement magnification mechanism, B1 to B3. ,,Block portion, C1°C2,,,Force acting portion, Dl-D4. ,, Stress concentration part, 13.15. . , laminated piezoelectric actuator

Claims (1)

[Scope of Claims] A plurality of rectangular block portions are arranged in a straight line, and have force acting portions for receiving deformation force at both ends in the longitudinal direction of the array of block portions. The block part and the force acting part are connected by a stress concentration part and the whole is integrally formed, and when a pair of deforming forces in opposite directions are applied to the force acting part in the longitudinal direction, the stress The position of each stress concentration portion is determined so that the entire stress concentration portion deforms in an arched manner due to the deformation of the concentrated portion, and the structure is configured such that the displacement of both ends due to the action of the pair of deforming forces is magnified as the amplitude of the aforementioned arched deformation. and an equal number of displacement amplifying mechanisms disposed at both ends of the displacement amplifying mechanism described above.
It has an even number of laminated piezoelectric actuators that apply a pair of deforming forces to a pair of force acting parts, and a drive circuit that drives these laminated piezoelectric actuators, and the even number of laminated piezoelectric actuators are connected in series. A displacement device characterized by: