JPH071454B2 - Control device for fine positioning device - Google Patents

Description

The present invention relates to a fine positioning device for performing fine displacement control on the order of sub-μm.

[Conventional technology]

In recent years, in various technical fields, a device capable of fine displacement adjustment on the order of sub-μm has been demanded. A typical example thereof is a semiconductor manufacturing apparatus such as an LSI (Large Scale Integrated Circuit), a mask aligner used in a manufacturing process of a VLSI, an electron beam drawing apparatus and the like. These devices require fine positioning on the order of sub-μm, and the degree of integration increases as the positioning accuracy improves.
High-performance products can be manufactured. Such fine positioning is necessary not only in the above-mentioned semiconductor device but also in various high-magnification optical devices such as electron microscopes, and by improving the accuracy, they can be used in advanced technologies such as biotechnology and space development. Will greatly contribute to the development of.

Conventionally, an apparatus shown in FIG. 7 has been proposed as such a fine positioning apparatus. That is, FIG. 7 is a side view of a conventional fine positioning apparatus. In the figure, 1 is a support, 2a, 2b
Is a plate-shaped parallel spring fixed on the support base 1 in parallel with each other, and 3 is a highly rigid fine movement table fixed on the parallel springs 2a and 2b. Reference numeral 4 denotes a fine movement actuator mounted between the support base 1 and the fine movement table 3. A piezoelectric element, an electromagnetic solenoid, or the like is used for the fine movement actuator 4, and when it is excited, a force in the x-axis direction of the coordinate axis shown in the drawing is applied to the fine movement table 3. Reference numeral 5 indicates a power supply for the fine movement actuator 4.

Because of the structure of the parallel springs 2a and 2b, the rigidity in the x-axis direction is low, while the rigidity in the Z-axis direction and the y-axis direction (direction perpendicular to the paper surface) is high, so that the fine motion actuator is excited. Then, the fine movement table 3 is displaced substantially only in the x-axis direction, and the displacement in the other direction hardly occurs. Therefore,
By exciting the fine movement actuator 4, the fine movement table 3 can be finely displaced by the distance ε ₁ in the x-axis direction as shown by the broken line in the figure.

By the way, although the fine movement table 3 is hardly displaced in directions other than the x-axis direction, the fine movement table 3 is displaced in the z-axis direction (downward in the figure) due to deformation of the parallel springs 2a and 2b as shown by the broken lines. To do.

Although this displacement (lateral displacement) is extremely small, it causes a serious error that cannot be ignored when high-precision fine positioning is required.

A fine positioning device which does not cause such a lateral displacement has been proposed by the present applicant in Japanese Patent Application No. 60-46443. This will be described with reference to the drawings. 8 (a) and 8 (b) are side views of the proposed fine positioning device. In the figure, 10,11a, 1
Reference numeral 1b is a rigid body portion, and 14a ₁ and 14a ₂ are parallel flexible beams connected in parallel to each other between the rigid body portions ₁₀ and 11a. Parallel flexible beam 14a ₁ , 1
4a ₂ is formed by a through hole 12a formed in the rigid body portion. 14
b ₁ and 14b ₂ are parallel flexural beams connected in parallel to each other between the rigid body portions 10 and 11b, and are formed by through holes 12b formed in the rigid body portions. 16a and 16b are piezoelectric actuators,
They are mounted between the protrusions from the rigid body that protrude into the through holes 12a and 12b, respectively. A parallel flexural beam displacement mechanism 19a is configured by the configuration on the left side of the center of the rigid body portion 10, and a parallel flexural beam displacement mechanism 19b is configured by the configuration on the right side.

Here, the coordinate axes are defined as shown (the y axis is the direction perpendicular to the paper surface). Now, a voltage is applied to the piezoelectric actuators 16a and 16b at the same time to generate a force f in the Z-axis direction of the same magnitude. At this time, a displacement occurring in one of the parallel flexible beam displacement mechanisms, for example, the parallel flexible beam displacement mechanism 19a will be considered.
When the voltage is applied to the piezoelectric actuator 16a, the rigid portion 10 is pressed in the z-axis direction by the force f. Therefore, the parallel flexible beams 14a ₁ and 14a ₂ undergo bending deformation in the same manner as the parallel springs 2a and 2b shown in FIG.
0 is displaced in the z-axis direction as shown in FIG. 8 (b). At this time, if the other parallel flexible beam displacement mechanism 19b does not exist, the lateral displacement described above should occur at the same time in the rigid portion 10 although it is extremely small.

Further, when the parallel flexible beam displacement mechanism 19a does not exist, considering the displacement generated in the other parallel flexible beam displacement mechanism 19b, the parallel flexible beam displacement mechanism 19b is a surface along the y-axis direction passing through the center of the rigid body part 10 (reference Since it is configured to be plane-symmetric with the flexural beam displacement mechanism 19a parallel to the plane), when a force f that is plane-symmetric with respect to the reference plane is received, the rigid body part
The lateral displacement occurs at the same time as the displacement in the z-axis direction, and the magnitude and direction thereof are plane-symmetric with that of the parallel flexible beam displacement mechanism 19a with respect to the reference plane. That is, regarding the lateral displacement, the lateral displacement generated in the parallel flexible beam displacement mechanism 19a is leftward in the figure for displacement in the x-axis direction, and counterclockwise in the figure for rotational displacement around the y-axis. The lateral displacement occurring in the parallel flexural beam displacement mechanism 19a occurs rightward in the figure for displacement in the x-axis direction and clockwise in the figure for rotational displacement around the y-axis. The magnitude of each x-axis direction displacement and the magnitude of rotational displacement about the y-axis are equal. Therefore, the lateral displacements that occur on both sides cancel each other. As a result, the force f is applied to each of the parallel flexible beams 14a ₁ , 14a ₂ , 14b ₁ and 14b ₂ only to cause a slight increase in the internal stress due to the elongation in the longitudinal direction.
10 produces displacement (main displacement) ε only in the z-axis direction.

When the voltage applied to the piezoelectric actuators 16a, 16b is removed, each of the parallel flexible beams 14a ₁ , 14a ₂ , 14b ₁ , 14b ₂ returns to the state before deformation, and the parallel flexible beam displacement mechanisms 19a, 19b become Returning to the state shown in FIG. 8A, the displacement ε becomes zero.

As described above, in the device shown in FIG. 8A, displacement (translational displacement) along one axial direction can be performed without causing lateral displacement, and the accuracy of displacement can be dramatically improved. it can.

The applicant of the present invention, further, by the above-mentioned Japanese Patent Application No. 60-46443,
In addition to the above-mentioned translational displacement, a fine positioning device that produces a fine rotational displacement about one axis has also been proposed. This will be described with reference to the drawings. 9 (a) and 9 (b) are side views of the proposed fine positioning device which causes rotational displacement. In the figure,
20, 21a and 21b are rigid bodies, and 24a ₁ , 24b ₂ , 24b ₁ and 24b ₂ are radiating flexible beams. Each radiating flexible beam 24a ₁ , 24a ₂ , 24b ₁ , 24b ₂ is an alternate long and short dash line with respect to an axis O perpendicular to the plane of the paper passing through the center of the rigid body 20.
It extends radially along L ₁ and L ₂ , and connects adjacent rigid body portions. The radial flexible beams 24a ₁ and 24a ₂ are formed by forming the through holes 22a, and the radial flexible beams 24b ₁ and 24b ₂ are formed by forming the through holes 22b. Reference numerals 26a and 26b denote piezoelectric actuators, which are mounted in the through holes 22a and 22b between the protruding portions protruding from the rigid body portion. Radial flexible beam displacement mechanism by the configuration on the left side of the axis O
29a is also a radial flexible beam displacement mechanism 29b due to the configuration on the right side.
Is configured.

Now, a predetermined voltage is applied to the piezoelectric actuators 26a and 26b at the same time to generate a force f of the same magnitude in the tangential direction with respect to a circle centered on the central axis O. Then, the rigid body part
The protrusion on the left side of 20 is pushed upward along the tangent line by the force generated in the piezoelectric actuator 26a, and the protrusion on the right side of the rigid body portion 20 is moved downward along the tangent line by the force generated in the piezoelectric actuator 26b. Pushed by. Since the rigid body portion 20 is connected to both the rigid body portions 21a and 21b by the flexural beams 24a ₁ , 24a ₂ , 24b ₁ and 24b ₂ , as a result of receiving the above force,
As shown in FIG. 9 (b), the radiating flexible beams 24a ₁ , 24a ₂ , 24
The portions of b ₁ and 24b ₂ that are connected to the rigid body portions 21a and 21b are on straight lines L ₁ and L ₂ that extend radially from the point O, but the portion that is connected to the rigid body portion 20 is the above straight line L ₁ , L ₂ slightly deviated from L ₂ (this straight line also extends radially from the point O) L ₁ ′, L ₂ ′ is displaced slightly on the displacement. Therefore, the rigid body portion 20 rotates clockwise by a minute angle δ in the figure. The magnitude of this rotational displacement δ is determined by the radial flexible beams 24a ₁ and 24a.
Since it is determined by the rigidity of ₂ , 24b ₁ and 24b ₂ against bending, if the force f is accurately controlled, the rotational displacement δ can be controlled with the same accuracy.

When the voltage applied to the piezoelectric actuators 26a, 26b is removed, the radiating flexible beams 24a ₁ , 24a ₂ , 24b ₁ , 24b ₂ return to the state before deformation, and the rotary displacement mechanism is shown in FIG. 9 (a). Returning to the state shown, the displacement δ becomes zero.

In the fine positioning device described above, in order to obtain a desired displacement with high accuracy, it is necessary to accurately control the voltage applied to each actuator. The control means used for this purpose in the case of translational displacement will be described with reference to FIG. 10 for the device shown in FIG.

FIG. 10 is a system diagram of a conventional control device. In the figure, 6 is the same fine positioning device as that shown in FIG. 7, and the same parts are designated by the same reference numerals. Reference numeral 7 denotes a mirror attached to the end face of the fine movement table 3 in the displacement direction. Reference numeral 30 is a laser length measuring device, which accurately measures a minute displacement of the fine movement table 3. The laser length measuring device 30 includes a laser head 31, an interferometer 32, a receiver 33 and a pulse comparator 34.
Is equipped with. The laser head 31 has, for example, a 2-frequency He-
Ne laser head is used and slightly different frequencies f ₁ and f ₂
In addition to outputting the laser light of, the signal (f ₁ −f ₂ ) proportional to the difference between the frequencies f ₁ and f ₂ is also output. The interferometer 32 sends only the laser light of the frequency f ₁ out of the laser light output from the laser head 31 to the mirror 7. Receiver
Reference numeral 33 outputs a signal calculated based on the frequency of the laser light sent from the interferometer 32. The pulse comparator 34 receives the signal from the laser head 31 and the receiver 33.
The signal based on this is added, and the signal based on this is added
Output as a signal.

35 is a signal V corresponding to the target displacement amount L of the fine positioning device 6.
3 is a signal converter for outputting the laser beam length measuring device 30 and a signal converter 36 for converting the output of the laser length measuring device 30 into a signal V'corresponding thereto
7, 38 are adders and 39 is a piezo amplifier. Piezo amplifier
39 outputs a required voltage to the actuator 4.

The operation of the control device will be described. Each laser beam from the laser head 31 is input to the interferometer 32 and
Only the laser light of f ₁ is applied to the mirror 7. At this time, when the fine movement table 3 is displaced, the irradiated laser light undergoes Doppler modulation due to the Doppler effect, and the frequency of the laser light reflected from the mirror 7 becomes (f ₁ ± Δf). The reflected laser light is input to the receiver 33 together with the laser light having the frequency f ₂ via the interferometer 32. At the receiver 33, {f ₂ − (f ₁
± Δf ₁ )} is calculated, and a signal corresponding to this is output. On the other hand, the laser head 31 outputs a signal (f ₁ −f ₂ ) corresponding to the difference in the frequency of each laser beam, and is input to the pulse comparator 34 together with the signal of the receiver 33. In the pulse comparator 34, based on both input values, {(f ₁ −f ₂ )
The calculation + f ₂ − (f ₁ ± Δf ₁ )} is executed, and as a result, the signal ± Δf ₁ is extracted. This signal ± Δf ₁ is a signal corresponding to the displacement of the fine movement table 3.

On the other hand, the signal converter 35 outputs a signal V corresponding to the target displacement L of the fine movement table 3. Further, the signal converter 36 outputs a signal V'corresponding to the output of the pulse comparator 34. This signal V'corresponds to the actual displacement amount of the fine movement table 3. The outputs of the signal converters 35 and 36 are input to the adder 37, and the deviation ΔV (ΔV = V−V ′) between the two is calculated, and the adder 38 outputs the deviation ΔV and the output signal V of the signal converter 35. Is added.
The output signal (V + ΔV) of the adder 38 is output to the piezo amplifier 39, and the piezo amplifier 39 outputs the drive voltage {k (V + ΔV)} of the actuator 4 proportional to this signal.

By such control means, a voltage is applied to the actuator 4 so that the deviation ΔV finally becomes 0, whereby the desired displacement L can be accurately generated on the fine movement table 3. .

It is obvious that the above control device can be applied to the fine positioning device shown in FIGS. 8 (a) and 9 (a) by attaching a mirror to the displacement portion (rigid body portions 10 and 20). is there.

[Problems to be Solved by the Invention]

By the way, a laser length-measuring device is used for the control device, but the laser length-measuring device has an extremely large volume and is expensive, and it is practical to install it for each fine positioning device. Impossible. Therefore, when the excellent fine positioning device shown in FIG. 8 (a) or FIG. 9 (a) is used, displacement with considerably high accuracy can be obtained, but displacement with higher accuracy is not necessarily obtained. There is a problem that it is not easy and the function of the fine positioning device having an excellent bending angle cannot be fully exerted.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a control device of a fine positioning device capable of performing highly accurate displacement control.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides a fine positioning device in which flat plate structural units each having a plate-shaped flexible beam and an actuator for acting between the rigid bodies are arranged symmetrically to each other. Displacement detecting means arranged for each of the flat plate structure units to detect a value relating to the displacement, and a target displacement amount of the fine positioning device are set, and a displacement of each flat plate structure unit corresponding to the target displacement amount is set. Displacement setting means for outputting a value involved in the, based on each deviation between each value involved in the displacement of each flat plate structure unit output from the displacement setting means and the value detected by each displacement detecting means Control means for controlling the voltage applied to the actuator is provided so as to eliminate each of these deviations.

[Action]

When the target displacement amount is set in the displacement setting means, the displacement setting means outputs a value relating to the displacement of each flat plate structural unit necessary for obtaining the set target displacement amount, and each value corresponding to each of these values is output. The actuator of the flat plate structure unit is driven. As a result, the plate-shaped flexible beam of each flat plate structure unit is deflected to displace the fine positioning device, and a value related to the displacement detected by each displacement detection means is output. Then, the voltage applied to the actuator of each flat plate structure unit is controlled so that these respective values and the values relating to the respective displacements output from the displacement setting means coincide with each other. As a result,
The fine positioning device is displaced by the target displacement amount.

〔Example〕

 Hereinafter, the present invention will be described based on the illustrated embodiments.

FIG. 1 is a block diagram of a control device for a fine positioning device according to an embodiment of the present invention. Before describing this control device, a fine positioning device in which the control device is used will be described with reference to the drawings.

2 (a) and 2 (b) are side views of the fine positioning apparatus according to the embodiment of the present invention. In the figure, the same parts as those shown in FIG. 8 (a) are designated by the same reference numerals. 40a ₁ , 40a ₂ , 40
Reference numerals a ₃ and 40a ₄ are strain gauges attached to the joint portions of the parallel flexible beams 14a ₁ and 14a _{2 with} the rigid body portions 10 and 11a in the parallel flexible beam displacement mechanism 19a. Further, 40b ₁ , 40b ₂ , 40b ₃ and 40b ₄ are also parallel flexible beams 14b in the parallel flexible beam displacement mechanism 19b.
_The strain gauges are attached to the connecting portions of ₁ and 14b _{2 with} the rigid body portions 10 and 11b. Each strain gauge changes its resistance value according to the applied strain.

The fine positioning apparatus FIG. 8 (a), as mentioned in the description of the operation of the apparatus (b), the piezoelectric actuator 16a, the parallel bending beams 14a by applying a predetermined voltage to 16b ₁ ~14b ₂ bends, causing a given translational displacement. This displacement amount L is proportional to the voltage applied to the piezoelectric actuators 16a and 16b. On the other hand, each of the parallel flexible beams 14a _{1 to} 14b ₂
When the strain is deflected, strain is generated in each strain gauge and its resistance value changes. Therefore, if these strain gauges are configured in an appropriate electric circuit, the amount of strain of each of the parallel flexible beams 14a _{1 to} 14b ₂ can be detected.

By the way, in the symmetrical fine positioning device as shown in FIG. 2 (a), it is impossible to configure the parallel flexible beam displacement mechanisms 19a, 19b completely identically, and the corresponding portions between the two are not provided. Inevitable variations in dimensions are unavoidable. In addition, there are some differences in the characteristics of the piezoelectric actuators 16a and 16b. Therefore, the piezoelectric actuator 16a,
Even if the same voltage is applied to 16b, the fine positioning device
The translational displacement shown in FIG. 2B is not performed, but the displacement is rotationally displaced to either side as shown in FIG. 2B. (Note that this rotational displacement is exaggerated.
Illustration of the strain gauge is omitted. ) This rotational displacement is indicated by the symbol α. In other words, when the same voltage is applied to the piezoelectric actuators 16a and 16b, the parallel flexible beam 1
Strain amount due to deflection of 4a ₁ and 14a ₂ and parallel deflection beam 14
This is different from the amount of strain due to the bending of b ₁ and 14b ₂ . If the two strain amounts are equal, these strain amounts become the displacement amount of the fine positioning device, but if they are different, the above-mentioned rotational displacement occurs and accurate fine positioning cannot be performed.

Therefore, in the present embodiment, the parallel flexible beam displacement mechanism 19
The strain amount of the parallel flexible beams 14a ₁ and 14a ₂ of a and the strain amount of the parallel flexible beams 14b ₁ and 14b ₂ of the parallel flexible beam displacement mechanism 19b are individually detected, and the accurate displacement amount is based on the detected value. The control for obtaining is obtained. Therefore, in this embodiment, means for detecting these two strain amounts is indispensable. This means will be described with reference to the drawings.

FIGS. 3A and 3B are circuit diagrams of the strain amount detection circuit. 40a ₁ , 40a ₂ , 40a ₃ , 40a ₄ , 40b ₁ , 40b ₂ , 40b ₃ , 40b
Reference numerals ₄ are strain gauges shown in FIG. Four
1a is a parallel flexible beam displacement mechanism 19a parallel flexible beam 14a ₁ , 14a ₂
The reference numeral 41b denotes a bridge circuit for detecting the strain amount of the parallel flexible beams 14b ₁ and 14b ₂ of the parallel flexible beam displacement mechanism 19b. In each bridge circuit 41a, 41b, each strain gauge is connected as shown in the figure. B is a DC power supply.

Now, assuming that a voltage is applied to the piezoelectric actuators 16a, 16b and a displacement as shown in FIG. 8 (b) occurs, the strain gauges 40a ₁ , 40a ₃ contract in the bridge circuit 41a,
The strain gauges 40a ₂ and 40a ₄ are stretched, their resistance values are changed accordingly, and the strain amounts ε ₁ are output in a form in which these variations are added. The same applies to the bridge circuit 41b, and the strain amount ε ₂ is output. Fig. 2 (b)
In the state shown in ( ₁₎ , the strain amount ε ₁ is larger than the strain amount ε ₂ .

Here, the control device of the fine positioning device shown in FIG. 1 using such strain amount detecting means will be described below. In FIG, 16a, 16b are piezoelectric actuator, 19a, 19b parallel flexure beams displacement _{mechanism, 40a 1 ~40a 4, 40b 1} ~40b 4 is a strain gauge, which are the same as those shown in FIG. 2 (a) Is.

Reference numeral 45 is a displacement amount setting device for setting a target displacement amount of the fine positioning device shown in FIG. 2 (a). When the target displacement amount L is set, the displacement amount setter 45 responds to the strain amounts ε ₁ , ε
₂ is output. That is, for the fine positioning device,
The outputs (strain amounts) ε ₁ and ε ₂ of the bridge circuits 41a and 41b when this displacement amount is obtained for a certain displacement amount are measured in advance,
This measurement is performed for each displacement amount. The displacement amount setter 45
Each measured strain amount is stored for each displacement amount.
When the target displacement amount L is input, the displacement amount setter 45 stores the stored strain amount measurement values ε ₁ and ε ₂ corresponding to the target displacement amount L.
Output and output.

The relationship between the strain amount and the displacement amount is shown in FIG.
In FIG. 4, the horizontal axis represents displacement and the vertical axis represents strain. The straight line A ₁ shows the output characteristic of the bridge circuit 41a, and the straight line A ₂ shows the output characteristic of the bridge circuit 41b. When the displacement amount is L, the strain amount ε ₁ is output from the bridge circuit 41a, and the strain amount ε ₂ is output from the bridge circuit 41b. Conversely, when a voltage is applied to the piezoelectric actuator 16a so that the output of the bridge circuit 41a becomes the value ε ₁ , and at the same time a voltage is applied to the piezoelectric actuator 16b so that the output of the bridge circuit 41b becomes the value ε ₂ , the displacement amount L Will be obtained.

46a, 46b are converters for converting (amplifying) the respective strain amounts ε ₁ , ε ₂ into a signal voltage v ₁ required for signal processing in proportion thereto, 47a,
47b, 48a and 48b are adders, and 49a and 49b are amplifiers. 50a, 50
b is a bridge circuit 41a, 41b, and these bridge circuits 41
It is a strain gauge equipped with an amplifier circuit for amplifying outputs ε ₁ ′ and ε ₂ ′ of a and 41 b to signal voltages v ₁ ′ and v ₂ ′ required for signal processing. Reference numeral 51 is a display device, which inputs the output signals of the strain gauges 50a and 50b, and displays the displacement amount of the fine positioning device based on these signals.

Next, the operation of this embodiment will be described. When the value L is input and set in the displacement amount setting device 45 in order to displace the fine positioning device shown in FIG. 2 (a) by the displacement amount L, the displacement amount setting device 45 causes the strain amounts ε ₁ , ε corresponding to the value L. ₂ is taken out and output individually. The distortion amount ε ₁ is input to the converter 46a, converted into the signal v ₁ , and input to the amplifier 49a via the adder 48a. The amplifier 49a generates a voltage which is proportional to the input signal v ₁ and has a level suitable for driving the voltage actuator 16a, and applies this voltage to the piezoelectric actuator 16a. As a result, the parallel flexural beams 14a ₁ and 14a _{2 of} the parallel flexural beam displacement mechanism 19a are flexed, and the strain gauge 40a ₁ is flexed accordingly.
Strain occurs at ~ 40a ₄ . As a result, from the strain gauge 50a, the detected strain amount ε ₁ ′ of the bridge circuit 41a at this time is obtained.
A signal v ₁ ′ proportional to is output.

The signal v ₁ ′ is input to the adder 47a, and as a result, the deviation Δv between the signal v ₁ and the signal v ₁ ′ is obtained. This deviation Δv and the signal v ₁ are added in the adder 48a, and this signal (v ₁ + Δv)
Is input to the amplifier 49a.

Hereinafter, the applied voltage of the piezoelectric actuators 16a and 16b is adjusted by repeating the above feedback control, and finally the strain amount ε ₁ is output from the bridge circuit 41a by the strain gauges 40a _{1 to} 40a _4. . That is,
The parallel flexible beams 14a ₁ and 14a ₂ of the parallel flexible beam displacement mechanism 19a are deflected by a predetermined amount. The same process is performed on the signal ε ₂ , and finally the bridge circuit 41b outputs the distortion amount ε ₂ . As a result, the fine positioning device is displaced by the target displacement amount L. On the other hand, the output signals of the strain gauges 50a and 50b are input to the display device 51, the displacement amounts corresponding to these signals are displayed, and the displacement amount L is finally displayed.

As described above, in the present embodiment, the strain amount of each parallel flexural beam displacement mechanism corresponding to a certain displacement amount is measured in advance, and when the target displacement amount is input, the signal corresponding to the actual displacement amount is measured in advance. Since the feed back control is performed so as to match the signal according to the strain amount, it is possible to perform highly accurate translational displacement. Further, since the control system can be constructed extremely small and inexpensive, it can be installed in each fine positioning device.

In the above description of the embodiment, when the target displacement amount is set in the displacement amount setter, the strain amount corresponding to this is output, and the strain amount is compared with the strain gauge. Obviously, the setter may output the displacement amount of each parallel flexural beam displacement mechanism corresponding to the target displacement amount, and the strain gauge may output the displacement amount corresponding to the strain amount.

Now, in the description of the above embodiment, the parallel flexible beams 14a ₁ , 14a ₂ ,
An example of detecting the amount of deformation of 14b ₁ and 14b ₂ using a strain gauge has been described. However, the above-mentioned deformation amount can be detected by other detecting means. Hereinafter, an example of using the other detecting means will be described.

FIGS. 5 (a) and 5 (b) are side views of another fine positioning apparatus to be controlled by the present invention. In FIG. 5 (a), the second
The same parts as those shown in FIG. 9A are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 11c is a support portion made of a rigid body, and is configured by extending from the rigid body portions 11a and 11b in parallel with the parallel flexible beams 14a ₁ and 14b ₂ and the bottom surface 10c of the rigid body portion 10. Reference numerals 60a and 60b are capacitance type displacement detectors fixed to the support portion 11c, and detect a distance δ between the upper end surface and the bottom surface 10c. The capacitance type displacement detectors 60a and 60b will be described later.

Now, when a predetermined voltage is applied to the piezoelectric actuators 16a, 16b, the parallel flexible beams 14a ₁ , 14a ₂ , 14b ₁ , 14b ₂ are deformed as shown in FIG. Bottom
10c is also displaced upward in the figure. Therefore, the interval δ also changes, and this changed interval is the capacitance type displacement detector 60a, 60b.
Detected by. Even if the displacement is not a translational displacement but an unbalanced displacement including a rotational displacement as shown in FIG. 2B, this is detected because the detection values of the capacitance type displacement detectors 60a and 60b are different. .

Therefore, when a displacement amount is set in the displacement amount setting device 45 shown in FIG. 1, a parallel flexible beam displacement mechanism corresponding to this displacement amount is set.
If the displacement amounts of 19a and 19b are output, by using these displacement amounts and the detection values of the capacitance type displacement detectors 60a and 60b, the capacitance type displacement detectors 60a and 60b can be obtained. Even in the case where the above is provided, it can be applied to the control device shown in FIG.

In Fig. 5 (b), the mounting position of the capacitance type displacement detector is the fifth position.
It is a side view of a fine positioning device different from that shown in FIG. 5A, and the same parts as those shown in FIG. The capacitance type displacement detectors 60a and 60b project inwardly from the rigid body 10 and are piezoelectric actuators.
It is fixed to the upper surfaces of the holding portions 10a, 10b holding the 16a, 16b. The capacitive displacement detectors 60a and 60b are located at positions facing the parallel flexible beams 14a ₁ and 14b ₁ , respectively.
When 4a ₁ and 14b ₁ are deformed, a change in the distance δ between them is detected. This fine positioning device can be applied to the control device shown in FIG. 1 as well as that shown in FIG. 5 (a).

Next, the configuration of such capacitance type displacement detectors 60a and 60b and the outline of the detection circuit will be described. FIG. 6 (a),
(B) is a cross-sectional view and bottom view of the capacitance type displacement detector,
FIG. 6 (c) is a circuit diagram of the detection circuit. Hereinafter, only the capacitance type displacement detector 60a will be described. In FIGS. 6A and 6B, 60a ₁ is a cylindrical center electrode, and 60a ₂ is a cylindrical electrode serving as the center electrode 60a ₁ . 60a ₃ is the center electrode 60a ₁
And a dielectric existing between the cylindrical electrode 60a ₂ and the cylindrical electrode 60a ₂ . The center electrode 60a ₁ and the cylindrical electrode 60a ₂ are configured so that their cross sectional areas are equal.

Here, the distance between the bottom surface of this capacitance type displacement detector 60a and the surface facing it is δ, the center electrode 60a ₁ and the cylindrical electrode
When the cross-sectional area of 60a ₂ is S and the dielectric constant of the dielectric is ε, the capacitance Ca between the central electrode 60a ₁ and the cylindrical electrode 60a ₂ is expressed by the following equation.

Ca = εS / δ Therefore, the capacitance Ca of this capacitance type displacement detector 60a
The interval δ can be detected by measuring

This capacitance Ca is detected by the detection circuit shown in FIG. 6 (c). In FIG. 6 (c), 61 is an oscillator, 62 is a capacitor for giving a reference electrostatic capacitance C _Y , 63 is an AC amplifier, 60a is the above capacitance type displacement detector, 64 is an AC / DC converter, and 65 is The DC amplifier 66 is a low-pass filter.

Here, the signal of the predetermined frequency and the predetermined voltage of the oscillator 61
and EEx, when amplifying a capacitance Ca of the electrostatic capacitance type displacement detector 60a in AC amplifier 63, whose output ea becomes _{ea = -eex · C Y / Ca} . This signal is exchanged into direct current by the AC / DC converter 64, span-adjusted and amplified by the DC amplifier 65, and shaped by the low-pass filter 66. And is output as a detection signal of the interval δ. That is, the gap δ can be detected by the capacitance displacement detector 60a.

In the description of the above embodiment, the fine positioning device that performs translational displacement is described as an example, but the control device of the present invention can also be applied to the fine positioning device shown in FIG. 9 (a) that performs rotational displacement. Is clear.

〔The invention's effect〕

As described above, in the present invention, the value involved in the displacement of one flat plate structural unit and the value involved in the displacement of the other flat plate structural unit corresponding to the target displacement amount are output and obtained by the displacement detection means. Since the control is performed so that the above value matches the above value, highly accurate displacement control can be performed.
Moreover, since the control device can be made compact and inexpensive, it can be installed for each fine positioning device.

[Brief description of drawings]

FIG. 1 is a block diagram of a control device of a fine positioning device according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are side views of a fine positioning device in which the control device shown in FIG. 1 is used. 3 (a) and 3 (b) are circuit diagrams of the strain gauge shown in FIG. 2 (a), FIG. 4 is a characteristic diagram showing the relationship between displacement and strain, and FIGS. 5 (a) and 5 (b). Is a side view of another fine positioning device used in the control device shown in FIG. 1, and FIGS. 6 (a), (b), and (c) are FIG. 5 (a) and FIG.
A sectional view, a bottom view and a detection circuit diagram of the capacitance type displacement detector shown in (b), FIG. 7, FIG. 8 (a), (b) and FIG. 9 (a), (b) are conventional. FIG. 10 is a side view of the fine positioning device, and FIG. 10 is a system diagram of a control device of the conventional fine positioning device. 19a, 19b …… Parallel flexible beam displacement mechanism, 24a ₁ , 24a ₂ , 24b ₁ , 24
b ₂ ...... Radial flexible beam, 29a, 29b …… Radial flexible beam displacement mechanism, 40a _{1 to} 40a ₄ , 40b _{1 to} 40b ₄ …… Strain gauge, 45 ……
Displacement setting device, 46a, 46b …… Transducer, 47a, 47b, 48a, 48b…
… Adder, 50a, 50b …… Strain type, 60a, 60b …… Capacitive displacement detector.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Ken Murayama, 650, Jinritsucho, Tsuchiura, Ibaraki Prefecture, Tsuchiura Plant, Hitachi Construction Machinery Co., Ltd. (56) References JP-A-61-209846 (JP, A)

Claims (6)

[Claims] 1. A fine positioning device in which flat plate structural units each having a plate-shaped flexural beam and a rigid body which are arranged to face each other between two rigid bodies are connected symmetrically to each other. Each displacement detection means arranged for each to detect the value involved in the displacement, and set the target displacement amount of the fine positioning device and the value involved in the displacement of each flat plate structural unit corresponding to this target displacement amount. Displacement setting means for outputting, and eliminating these respective deviations based on the respective deviations of the respective values involved in the displacement of each flat plate structural unit output from the displacement setting means and the values detected by the respective displacement detecting means And a control means for controlling the voltage applied to the actuator. 2. The fine positioning device according to claim 1, wherein the flat plate structural unit is a parallel flat plate structural unit in which the plate-shaped flexible beams are arranged in parallel with each other. 3. The flat plate structural unit according to claim 1, wherein the flat plate structural unit is a radial flat plate structural unit in which the plate-shaped flexible beams are radially arranged with respect to a predetermined axis. Fine positioning device. 4. A fine positioning device according to claim 1, wherein the actuator is a laminated piezoelectric element. 5. A fine positioning device according to claim 1, wherein the displacement detecting means is a strain gauge provided at a predetermined position of the plate-shaped flexible beam. 6. The device according to claim 1, wherein the displacement detecting means is a capacitance type detector provided at a position facing a displaced portion of the fine positioning device. Fine positioning device.