JP2960112B2 - Micro displacement device - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial application field) The present invention relates to a minute displacement device capable of precisely displacing a movable portion.

(Prior Art) As a minute displacement device for minutely displacing a movable part, a pair of parallel springs is erected on a base, and the movable part is elastically supported by these parallel springs. There is known a configuration in which the movable portion is displaced by deforming the parallel spring with an actuator such as a piezoelectric element.
Such a minute displacement device has advantages such as a simple configuration and easy manufacture.

Conventionally, in the minute displacement device having the above configuration, the parallel spring has been formed of a steel material, a non-ferrous metal material, or the like.

(Problems to be Solved by the Invention) However, steel materials and non-ferrous metal materials do not have uniform mechanical properties such as Young's modulus and thermal properties. For this reason, parallel springs made of steel or non-ferrous metal do not show constant mechanical characteristics, so the amount of deformation when driven by an actuator is not constant, and thus the movable part is minutely displaced with high precision. Was not possible.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a minute displacement device capable of minutely displacing a movable portion with high accuracy.

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

According to such a configuration, the spring portion formed of single-crystal silicon has more uniform mechanical properties than those formed of a steel material or a non-ferrous metal material, so that the movable portion can be displaced with high precision. Becomes possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 5 show a first embodiment of the present invention.
The micro displacement device shown in FIG. 1 includes a device main body 1 formed of a single crystal silicon in a cubic shape. In the device main body 1, a cavity 2 penetrating in the width direction thereof is formed by processing. The main body 1 is formed by the cavity 2.
, A lower fixed portion 3, an upper movable portion 4, and side wall portions 5 on both sides are formed. The pair of side walls 5 are opposed to each other in parallel and spaced apart from each other.
Are engraved along the width direction of the apparatus main body 1. These grooves 6 form a thin hinge 7 on the side wall 5. The pair of side wall portions 5 are parallel springs 8 that can be elastically deformed in the left-right direction orthogonal to the width direction of the apparatus main body 1 with the hinge portion 7 as a fulcrum. That is, if the lower fixed part 3 of the apparatus main body 1 is fixed, the upper movable part 4
Can be displaced in the left-right direction.

A fixed arm 11 protrudes from the upper surface of the fixed portion 3 along the width direction of the apparatus main body 1, and a movable arm 12 parallel to one side surface of the fixed arm 11 is provided on a lower surface of the movable portion 4.
Is hanging. At the center in the width direction of the fixed arm 11, a mounting hole 13 is formed. In addition, the fixed arm
The one side wall portion 5 located on the other side surface of the
An insertion hole 14 is formed so as to face the hole. A holder 16 to which a rod-shaped piezoelectric element 15 as an actuator is fixed at a distal end from the insertion hole 14 to the mounting hole 13 is inserted. The holder 16 is fixed by a fixing screw 17 screwed from an end face in the width direction of the fixing arm 11. The tip surface of the piezoelectric element 15 is connected to the movable arm 12 via a sphere 18.
Is in contact with That is, the piezoelectric element 15 is provided in a state where the movable arm 12 is pressed in the direction indicated by the arrow in FIG. The sphere 18 is provided integrally with either the piezoelectric element 15 or the movable arm 12.

The piezoelectric element 15 expands according to a voltage value applied to the piezoelectric element. When the piezoelectric element 15 is extended, the movable arm 12 is pressed, so that the movable part 4 is displaced in the direction of the arrow while elastically deforming the parallel spring 8 as shown by a chain line in FIG. When the voltage applied to the piezoelectric element 15 is removed, the movable portion 4 returns to the original position by the restoring force of the parallel spring 8.

Strain gauges 19 are provided on the outer surfaces of the pair of side walls 5 of the apparatus main body 1 at positions corresponding to the hinges 7 respectively. In other words, a total of four strain gauges
19 are provided. Since the device main body 1 is made of single-crystal silicon, these strain gauges 19 are formed by diffusing impurities by a photolithography technique similar to the IC manufacturing process. As shown in FIG. 3, the strain gauge 19 includes a strip-shaped piezoresistor 21 bent in a meandering shape and wiring pads 22 for taking out lead wires provided at both ends of the piezoresistor.
Consists of

The four strain gauges 19 provided in the apparatus body 1
As shown in the figure, a bridge circuit 25 is formed. A constant voltage Vcc is applied to the bridge circuit 25, and an output voltage Vs is obtained. This output voltage Vs is input to the first amplifier circuit 26. Thereby, the first amplifier circuit
The comparison voltage Vc is output from 26, and the comparison voltage Vc is input to the difference circuit 27.

A control voltage Vi for driving the piezoelectric element 15 is input to the difference circuit 27. The difference circuit 27 controls the control voltage Vi.
And the output voltage Vc.
This difference voltage e is amplified by a second amplifier circuit 28 and
Entered in 29. The piezoelectric element 15 is connected to the drive circuit 29. Therefore, the piezoelectric element 15 is displaced according to the magnitude of the difference voltage e.

When the movable element 4 of the apparatus main body 1 is displaced by driving the piezoelectric element 15, the parallel spring 8 is elastically deformed. When the parallel spring 8 is deformed, a strain is generated in the strain gauge 19 and the balance of the bridge circuit 25 is lost. Therefore, as described above, the output voltage Vs output from the bridge circuit 25 becomes the first amplifier circuit.
The signal is amplified at 28 and input to the difference circuit 27.

When the piezoelectric element 15 is displaced in accordance with the magnitude of the control voltage Vi, 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 Vc becomes equal to the control voltage Vi. Therefore, the difference voltage e is not output from the difference circuit 27. However, when the piezoelectric element 15 does not deform by an amount corresponding to the voltage value of the control voltage Vi, a difference occurs between the control voltage Vi input to the difference circuit 27 and the comparison voltage Vc from the bridge circuit 25. Therefore, a difference voltage e corresponding to the difference is output from the difference circuit 27, and the piezoelectric element 15 is driven by the difference voltage.

That is, since the piezoelectric element 15 usually has a hysteresis as shown in FIG. 6 (a), it is difficult to precisely displace the movable portion 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 does not have a hysteresis in the displacement d of the movable portion 4 as shown in FIG. 15 can be driven. That is, the movable section 4 of the apparatus main body 1 can be precisely driven.

According to the micro-displacement device having the above-described configuration, since the device main body 1 is formed of single-crystal silicon, which is a homogeneous material, it is possible to make the mechanical characteristics of the parallel spring 8 such as the Mang ratio and the thermal characteristics constant. it 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 portion 4 can be minutely displaced precisely.

Further, since the device main body 1 is formed of single crystal silicon, the strain gauge 19 for detecting the amount of deformation of the parallel spring 8 can be formed by the same photolithography technique as in the IC manufacturing process. As a result, the performance of the strain gauge 19 is not affected by the adhesive as in the conventional case where a strain gauge separate from the apparatus main body 1 is attached to the measurement site with an adhesive, so that the detection accuracy is improved. I do. Further, since the strain gauge 19 does not peel off from the apparatus main body 1, the durability can be improved.

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

The apparatus main body 31 shown in FIG. 7 is composed of two single crystal silicon plates 34 on which hinge portions 33 and parallel springs 8 are formed by forming a pair of grooves 32 in the upper and lower ends of the inner surface along the axial direction.
Are bonded and fixed to both end surfaces of a plate-like fixed portion 35 and a movable portion 36 which are arranged in parallel in the vertical direction and opposed to each other.
A fixed arm 37 is protruded from the fixed portion 35, and a movable arm 38 is suspended from the movable portion 36. The fixed part 35 and the movable part 36
Is made of a material other than single crystal silicon.

Even in the apparatus main body 31 configured as described above, the mechanical properties of the parallel spring 8 can be improved as in the first embodiment, and the strain gauge 19 can be formed by photolithography.

The apparatus main body 41 shown in FIG. 8 has a thin elastic plate 43 made of single-crystal silicon on the upper and lower end surfaces of a pair of band members 42.
Attach one end in the vertical direction. The other end of the lower elastic plate 43 is attached to a plate-like fixed portion 44, and the other end of the upper elastic plate 43 is attached to a movable portion 45. A fixed arm 46 protrudes from the fixed part 44, and a movable arm 47 is vertically provided from the movable part 45. That is, the band-shaped 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 is substantially the same as the structure shown in FIG. 7, except that a groove 32a formed in the single crystal silicon plate 34 is formed.
Is formed in a trapezoidal taper shape by anisotropic etching.

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

The apparatus main body 61 shown in FIG. 10 is almost the same as the apparatus main body 1 shown in FIG. 1, but differs in the following points. The apparatus main body 61 of this embodiment has a structure in which the deformation of the piezoelectric element 15 is enlarged to displace the movable section 4. That is, the device body 1
Between the fixed portion 3 and the movable portion 4, in addition to the pair of parallel springs 8, both ends of the expanding member 62 are integrally formed via thin hinge portions 63. One end of the piezoelectric element 15 is attached to a fixed arm 11 protruding from the fixed portion 3, and the other end of the piezoelectric element 15 is in contact with the lower end of the expanding member 62 via a sphere 18.

According to such a configuration, when the piezoelectric element 15 is deformed,
In accordance with the amount of the deformation, the lower end of the expanding member 62 is rotated and displaced around the lower hinge 63 as a fulcrum. This expanding member 62
Because the displacement of the upper end of is larger than the displacement of the lower end,
The movable part 4 connected to the upper end of the enlarging member 62 includes the piezoelectric element 15.
Will be displaced by a large amount of displacement compared to the amount of deformation.

FIG. 11 shows a micro displacement device formed by stacking three main bodies 71, 72, 73 of X, Y, Z having the same configuration as that shown in FIG. That is, the Z device main body 73 at the uppermost stage is arranged along the Z direction among the three axial directions of X, Y and Z indicated by arrows in FIG. This Z
At one end of the fixed portion 3 of the apparatus main body 71, a first ridge 74 is provided so as to protrude over the entire length in the width direction.
A second ridge 75 protrudes from one end opposite to 74.

A base plate 76 fixedly disposed on the first ridge 74
Is fixed. One end of the fixing portion 3 of the Y device main body 72 is fixed to the second ridge 75. The Y device main body 72 is fixed to the second ridge 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 joined and fixed to the movable portion 4 of the Y device main body 72. The X device main body 71 is provided such that the displacement direction of the movable part 4 is along the X direction, and the mounting plate 77 is joined and fixed to the movable part 4. This mounting plate 77
A driven body (not shown) can be attached to the device.

Although not shown, each device body 71, 72, 73 has a first
Piezoelectric element for driving movable section 4 as in the configuration shown in FIG.
15 are provided. Therefore, if the movable section 4 of each apparatus main body is driven by the piezoelectric element 15, the mounting plate 77 attached to the movable section 4 of the X apparatus main body 71 can be driven in the three axes of X, Y, and Z. It has become.

In the embodiment shown in FIG. 11, each apparatus main body may be configured as shown in FIGS. 7 to 10.
Further, the X, Y, and Z device main bodies may not be formed separately, but may be integrally formed of one single crystal silicon. In that case, it is necessary to consider the shape of the base plate 76 and the like so that a strain gauge can be formed in the Z apparatus main body. Alternatively, only the Z device main body may be separated, and the X device main body and the Y device main body may be integrally formed of one single crystal silicon.

Further, the mounting plate is displaced in three axial directions by three device main bodies, but may be configured to be displaced in two axial directions by two device main bodies.

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

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

[Brief description of the drawings]

FIG. 1 is a perspective view of an apparatus main body showing a first embodiment of the present invention, FIG. 2 is a side view thereof, FIG. 3 is an enlarged perspective view of a strain gauge part, and FIG. 4 shows a hysteresis of a piezoelectric element. FIG. 5 is an explanatory view showing a state in which the movable portion of the apparatus main body is driven by the piezoelectric element, and FIG. 6A is a diagram showing a conventional relationship between voltage and displacement in which hysteresis occurs in the piezoelectric element. FIG. 6 (b) is a graph showing the relationship between voltage and displacement of the present invention in which hysteresis has been removed from the piezoelectric element, and FIGS. 7 to 9 show second to fourth embodiments of the present invention, respectively. FIG. 10 is a perspective view of the apparatus main body, FIG. 10 is a cross-sectional view of the apparatus main body showing a fifth embodiment of the present invention, and FIG. 11 is a perspective view of a state in which three apparatus main bodies showing a sixth embodiment of the present invention are stacked. FIG. 1, 31, 41 ... device body, 3, 35, 44 ... fixed part, 4 ...
… 36, 45… Movable part, 8… Parallel spring (spring part), 15…
... Piezoelectric elements (actuators).

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16F 1/00-6/00 B25J 19/00

Claims (4)

(57) [Claims] An apparatus body having a spring portion and a movable portion elastically displaceable by the spring portion, and the movable portion is displaced by elastically deforming the spring portion provided on the device body. A micro-displacement device, comprising: an actuator for causing the device body to have at least a spring portion made of single-crystal silicon. 2. A strain gauge for detecting a strain generated when the movable portion of the apparatus body is elastically displaced is formed in the spring portion by diffusing single crystal silicon impurities forming the spring portion. Claim 1 characterized by the following.
Item 6. The micro displacement device according to Item 1. 3. The spring section is provided with a plurality of strain gauges constituting a bridge circuit, and the actuator is connected to control means for feeding back an output from the bridge circuit. The minute displacement device according to claim 2. 4. The minute displacement device according to claim 1, wherein a plurality of device main bodies are stacked with the respective spring portions deformed in different directions.