JPH0434226A - Minute displacement device - Google Patents

Abstract

PURPOSE:To drive a movable section by an actuator with high accuracy by forming at least a spring section of the device proper by single crystal silicon so as to make mechanical characteristics such as Young's modulus and heat characteristics uniform. CONSTITUTION:Since a piezo-electric device usually provides hysteresis, it is difficult to precisely displace a movable section 4 in accordance with voltage value to be added on the piezo-electric device 15. But, if the piezo-electric device 15 is controlled by feeding back output from a bridge circuit, the piezo-electric device 15 is driven without causing hysteresis in displacement amount d of the movable section 4. That is, the movable section of the device proper 1 is precisely driven. Since the device proper 1 is formed by single crystal silicone which is uniform material, it is possible to make mechanical characteristics such as Young's modulus and heat characteristics of a parallel spring 8 constant. For this reason, since deformation amount is made constant when the parallel spring 8 is driven by the piezo-electric device 15, it is possible to precisely displace the movable section 4 minutely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a minute displacement device that can precisely displace a movable part.

(Prior Art) As a micro-displacement device for minutely displacing a movable part, a pair of parallel springs are installed upright on a base, and the movable part is elastically supported by these parallel springs.

A device is known in which the movable portion is displaced by deforming the parallel spring using an actuator such as a piezoelectric element. Such a micro-displacement device has the advantage of being simple in structure and easy to manufacture.

Conventionally, in the micro displacement device having the above configuration, the parallel springs have been formed of a steel material, a non-ferrous metal material, or the like.

(Problems to be Solved by the Invention) However, mechanical properties such as Young's modulus and thermal properties of steel materials and non-ferrous metal materials are not uniform. Therefore,
Parallel springs made of steel or non-ferrous metal materials do not exhibit constant mechanical properties, so the amount of deformation when driven by an actuator is not constant, and as a result, the movable part cannot be displaced minutely with high precision. That happened.

The present invention was made based on the above-mentioned circumstances, and its object is to provide a micro-displacement device capable of micro-displacing a movable part with high precision.

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to solve the above problems, the present invention includes a device main body having a spring portion and a movable portion that is elastically displaceable by the spring portion. , an actuator provided on the device body to elastically deform the spring portion to displace the movable portion, and at least the spring portion of the device body is formed of single crystal silicon. .

With this configuration, the spring part made of single crystal silicon has more homogeneous mechanical properties than those made of steel or non-ferrous metal materials, making it possible to displace the movable part with high precision. becomes possible.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show a first embodiment of the invention. The micro-displacement device shown in FIG. 1 includes a device main body 1 formed in a cubic shape from single-crystal silicon. The device body 1 is machined to have a cavity 2 extending therethrough in its width direction.

This hollow part 2 allows the device body 1 to have a lower fixing part 3.
, an upper movable part 4, and side wall parts 5 on both sides. A pair of side wall portions 5 are spaced apart from each other in parallel and face each other, and grooves 6 are formed along the width direction of the device main body 1 on the upper and lower ends of their inner surfaces, respectively. These grooves 6 form a thin hinge portion 7 in the side wall portion 5 . The pair of side wall portions 5 are parallel springs 8 that are elastically deformable in the left-right direction orthogonal to the width direction of the device main body 1 using the hinge portion 7 as a fulcrum. That is, by fixing the lower fixed part 3 of the apparatus main body 1, the upper movable part 4 can be displaced in the left-right direction.

A fixed arm 11 is provided on the upper surface of the fixed portion 3 to protrude along the width direction of the device body 1, and a movable arm 12 is provided on the lower surface of the movable portion 4 in parallel to one side of the fixed arm 11. It is installed vertically. A mounting hole 13 is bored in the center portion of the fixed arm 11 in the width direction. Furthermore, an insertion hole 14 is formed in one side wall portion 5 located on the other side of the fixed arm 11 so as to face the mounting hole 13 .

A holder 16 having a rod-shaped piezoelectric element 15 fixed thereto as an actuator is inserted into the attachment hole 13 from the insertion hole 14 .

This holder 16 is fixed by a fixing screw 17 screwed into the end face of the fixing arm 11 in the width direction. The tip end surface of the piezoelectric element 15 is in contact with the movable arm 12 via the sphere 18. That is, the piezoelectric element 15 is provided in a state in which the movable arm 12 is pressed in the direction shown by the arrow in FIG.

The above body 18 is the piezoelectric element 15 or the movable arm 12
It is installed integrally in one of the two districts.

The piezoelectric element 15 expands depending on the voltage value applied thereto. When the piezoelectric element 15 extends, the movable arm 12
is pressed, the movable portion 4 is displaced in the direction of the arrow while elastically deforming the parallel spring 8 as shown by the chain line in FIG. When the voltage applied to the piezoelectric element 15 is removed, the movable portion 4 returns to its original position due to the restoring force of the parallel spring 8.

Strain gauges 19 are provided on the outer surfaces of the pair of side wall portions 5 of the apparatus main body 1 at positions corresponding to the hinge portions 7, respectively. That is, a total of four strain gauges 19 are provided in the device main body 1. Since the device body 1 is made of single crystal silicon, these strain gauges 19 are formed by diffusing impurities such as boron using a photolithography technique similar to the IC manufacturing process. As shown in FIG. 3, the strain gauge 19 consists of a band-shaped piezoresistor 21 bent in a meandering manner, and wiring pads 22 for taking out lead wires provided at both ends of the piezoresistor.

The four strain gauges 19 provided in the device main body 1 are
As shown in the figure, a bridge circuit 25 is formed. A constant voltage vec is applied to this bridge circuit 25, so that an output voltage Vs can be obtained. This output voltage Vs
is input to the first amplifier circuit 26. As a result, the first amplifier circuit 26 outputs the comparison voltage Vc, and this comparison voltage Ve is input to the difference circuit 27.

A control voltage Vl for driving the piezoelectric element 15 is input to the difference circuit 27. This differential circuit 27 outputs a differential voltage e corresponding to the difference between the control voltage V and the output voltage Ve. This differential voltage e is amplified by the second amplifier circuit 28 and input to the drive circuit 29. The piezoelectric element 15 is connected to this drive circuit 29 . Therefore, the piezoelectric element 15 is adapted to be displaced in accordance with the magnitude of the differential voltage e.

When the piezoelectric element 15 is driven and the movable part 4 of the device main body 1 is displaced, the parallel spring 8 is elastically deformed.

When the parallel spring 8 deforms, distortion occurs in the strain gauge 19 and the balance of the bridge circuit 25 is lost. Therefore, the output voltage Vs output from the bridge circuit 25 is amplified by the first amplifier circuit 28 as described above. and input it to the difference circuit 27.

When the piezoelectric element 15 is displaced according to the magnitude of the control voltage Vl, the output voltage Vs from the bridge circuit 25 is amplified by the first amplifier circuit 26, and the comparison voltage output from the first amplifier circuit 26 is Vc becomes equal to the control voltage v1. Therefore, the differential voltage e is not outputted from the differential circuit 27. However, if the piezoelectric element 15 does not deform by an amount corresponding to the voltage value of the control voltage v1,
A difference occurs between the control voltage V1 input to the difference circuit 27 and the comparison voltage Vc from the bridge circuit 25.

Therefore, the differential circuit 27 outputs a differential voltage e corresponding to the difference, so that the differential voltage causes the piezoelectric element 15 to
will be driven.

That is, since the piezoelectric element 15 usually has hysteresis as shown in FIG. 6(a), it is difficult to precisely displace the movable part 4 according to the voltage value applied to the piezoelectric element 15. However, if the piezoelectric element 15 is controlled by feeding back the output from the bridge circuit 25 as described above, the piezoelectric element 15 can be controlled without causing hysteresis in the displacement amount d of the movable part 4, as shown in FIG. 6(b). 15 can be driven. In other words, the movable part 4 of the device main body 1 can be driven precisely.

According to the micro-displacement device having the above configuration, since the device main body 1 is made of single crystal silicon, which is a homogeneous material, it is possible to keep the mechanical properties such as the Young's modulus and thermal properties of the parallel springs 8 constant. can.

Therefore, since the amount of deformation when the parallel spring 8 is driven by the piezoelectric element 15 can be made constant, the movable part 4 can be precisely and minutely displaced.

Further, since the device main body 1 is made of single crystal silicon, the parallel springs 8 can be deformed. Therefore, the performance of the strain gauge 19 is not affected by the adhesive, unlike the conventional method in which a strain gauge separate from the device main body 1 is attached to the measured area with adhesive, improving detection accuracy. do. Also, from the device main body 1 to the strain gauge 19
Since there is no possibility of peeling off, durability can be improved.

7 to 11 show second to sixth embodiments of the present invention.

The main body 31 of the device shown in FIG.
Two single-crystal silicon plates 34 on which parallel springs 8 are formed are adhesively fixed to both end surfaces of a plate-shaped fixed part 35 and a movable part 36, which are arranged vertically in parallel and spaced apart from each other. A fixed arm 37 is provided protruding from the fixed portion 35, and a movable arm 38 is provided vertically from the movable portion 36. The fixed part 35 and the movable part 36 are made of a material other than single crystal silicon.

Even in the apparatus main body 31 configured in this way, the mechanical characteristics of the parallel spring 8 are similar to those of the first embodiment.The apparatus main body 41 shown in FIG. One end of a thin elastic plate 43 made of silicon in the vertical direction is attached.

The other end of the lower elastic plate 43 is attached to a plate-shaped fixed part 44, and the other end of the upper elastic plate 43 is attached to a movable part 45.

A fixed arm 46 is provided protruding from the fixed portion 44, and a movable arm 47 is provided vertically from the movable portion 45. In other words, the strip member 42 and the elastic plate 43 form a parallel spring.

According to such a configuration, the elastic plate 43 is elastically deformed and the movable plate 45 is displaced, and the strain gauge 19 can be formed on the elastic plate 43 made of single crystal silicon.

The device main body 51 shown in FIG. 9 has almost the same structure as the one shown in FIG.
The difference is that 2a is formed into a trapezoidal tapered shape by anisotropic etching.

In the embodiment shown in FIGS. 7 to 9, although not shown, the movable portion is driven by a piezoelectric element, as in the first embodiment.

The device main body 61 shown in FIG. 10 is the device main body 1 shown in FIG.
It is almost the same as , but differs in the following points. The device main body 61 of this embodiment has a structure in which the movable portion 4 is displaced by magnifying the deformation of the piezoelectric element 15. That is, in addition to the pair of parallel springs 8, both ends of an expanding member 62 are integrally formed between the fixed part 3 and the movable part 4 of the device main body 1 via thin hinge parts 63. . One end of the piezoelectric element 15 is attached to a fixed arm 11 projecting from the fixed part 3, and the other end abuts the lower end of the enlarged member 62 via a sphere 18.

According to such a configuration, when the piezoelectric element 15 is deformed,
Depending on the amount of deformation, the lower end portion of the expanding member 62 is rotated about the lower hinge portion 63 as a fulcrum. Since the amount of displacement at the upper end of the expanding member 62 is larger than the amount of displacement at the lower end, the movable portion 4 connected to the upper end of the expanding member 62 is displaced by a larger amount of displacement than the amount of deformation of the piezoelectric element 15. It turns out.

In FIG. 11, three device bodies 71, 72, and 73 of X1Y and Z having the same configuration as shown in FIG. 1 are stacked to form a minute displacement device. In other words, the top Z device main body 73
xSy indicates the direction of displacement of the movable part 4 with an arrow in the same figure,
It is arranged along the Z direction among the three axial directions of Z. A first protrusion 74 is provided on one end of the fixed part 3 of the two device main bodies 71 to protrude over the entire length in the width direction, and a second protrusion 74 is provided on the movable part 4 at one end opposite to the first protrusion 74. A strip 75 is provided protrudingly.

The base plate 7 is fixedly disposed on the first protrusion 74.
6 is fixed. The second protrusion 75 has the Y
One end of the fixing portion 3 of the device main body 72 is fixed. This Y device main body 72 is fixed to the second protrusion 75 of the Z device main body 71 with the displacement direction of the movable portion 4 along the Y direction.

The fixed portion 3 of the X device main body 71 is bonded and fixed to the movable portion 4 of the Y device main body 72. This X device main body 71 is
The displacement direction of the movable part 4 is provided along the X direction,
A mounting plate 77 is bonded and fixed to the movable part 4. A driven body (not shown) is attached to this attachment plate 77.

Although not shown, each device body 71, 72, 73 is provided with a piezoelectric element 15 for driving the movable part 4, similar to the configuration shown in FIG. Therefore, if the movable part 4 of each device main body is driven by the piezoelectric element 15, the mounting plate 77 attached to the movable part 4 of the X device main body 71 can be moved to X5YSZ.
It can be driven in three axial directions.

In the embodiment shown in FIG. 11, each device main body may have the configuration shown in FIGS. 7 to 10. Also, instead of having the x, y, and z device bodies as separate bodies, one
It may also be integrally formed of single crystal silicon. In that case, it is necessary to consider the shape of the base plate 76 so that a strain gauge can be formed in the main body of the Z device. Alternatively, only the Z device main body may be made separate, and the X device main body and the Y device main body may be integrally formed from one single crystal silicon.

Furthermore, although the mounting plate is configured to be displaced in three axial directions by three device bodies, it may be configured to be displaced in two axial directions by two device bodies.

In the embodiment shown in FIGS. 7 to 11, the strain gauges provided on each spring portion are assembled into a bridge circuit similar to the first embodiment. The output from this bridge circuit is used as a feedback control signal to eliminate hysteresis of the piezoelectric element.

[Effects of the Invention] As described above, the present invention provides a device main body having a spring portion and a movable portion that is provided to be elastically displaceable by the spring portion, and in which the movable portion is moved by deforming the spring portion. In the micro displacement device provided with an actuator for displacement, at least the spring portion of the device main body is formed of single crystal silicon. Therefore, the mechanical properties such as Young's modulus and thermal properties of the spring portion can be made uniform, so that the movable portion can be driven with high precision by the actuator.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the main body of the device showing the first embodiment of the present invention, Fig. 2 is a side view, Fig. 3 is an enlarged perspective view of the strain gauge section, and Fig. 4 shows the hysteresis of the piezoelectric element. A control circuit diagram for removing the device, FIG.
a) is a graph of the conventional voltage-displacement relationship in which hysteresis occurs in the piezoelectric element, FIG. 6(b) is a graph of the voltage-displacement relationship of the present invention in which hysteresis is removed from the piezoelectric element, and FIGS. 9 are the second to fourth figures of this invention, respectively.
FIG. 10 is a sectional view of the device main body showing a fifth embodiment of the present invention, and FIG. 11 shows three device main bodies showing the sixth embodiment of the invention. It is a perspective view of a stacked state. 1.31.41...Device body, 3.35.44...
Fixed part, 4...36.45...Movable part, 8...Parallel spring (spring part), 15...Piezoelectric element (actuator). Figure 1 Applicant's Agent Patent Attorney Takehiko Suzue Figure 2 Figure Figure Figure Figure Figure (a) (b) Figure Figure Figure

Claims (4)

[Claims] (1) A device body having a spring portion and a movable portion that is provided to be elastically displaceable by the spring portion, and an actuator that is provided in the device body and displaces the movable portion by elastically deforming the spring portion. A micro-displacement device, characterized in that at least the spring portion of the device main body is formed of single crystal silicon. (2) A strain gauge is formed in the spring portion by diffusing impurities to detect the strain that occurs when the movable portion of the device main body is elastically displaced. The minute displacement device according to item 1. (3) The minute displacement device according to claim 1, wherein the actuator is connected to a control means for eliminating hysteresis of the actuator. (4) The micro-displacement device according to claim 1, wherein a plurality of device bodies are stacked with their respective spring portions deformed in different directions.