JPS63184112A - Controller for fine positioning device - Google Patents

Abstract

PURPOSE:To perform displacement with high accuracy, by detecting the displaced quantity of undesired displacement form, and applying feedback control so as to set the quantity to zero. CONSTITUTION:A fine positioning device is provided with piezoelectric actuators 16a-16b, parallel deflective beam displacement mechanisms 19a-19b, and strain gages 40a1-404, etc., and a controller for the device is constituted by providing with a feedback control system consisting of a setting apparatus 45 for a targeted displaced quantity, adders 46 and 49, a gain adjustor 47, and an integrator 48, etc., and also with strain gauges 51-52 and a display device 54. In such a way, when the actuators 16a-16b are driven and a plate shaped deflective beam is deflected and displaced, the displacement is detected with the strain gauges 51-52, and the displaced quantity of a desired form and that of a form other than the desired form can be found. And an applying voltage on each actuator is controlled so as to coincide the displaced quantity of the desired displacement form with the targeted displaced quantity, and also, to set the displaced quantity of the form other than the desired displacement form at zero.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fine positioning device that performs fine displacement control on the order of sub-μm.

[Conventional technology]

In recent years, in various technical fields, there has been a demand for devices capable of making fine displacements on the order of sub-μm. Typical examples are semiconductor manufacturing equipment such as mask aligners and electron beam lithography equipment used in the manufacturing process of LSIs (Large Scale Integrated Circuits) and VLSIs. These devices require fine positioning on the order of sub-μm,
As the positioning accuracy improves, the degree of integration also increases, making it possible to manufacture high-performance products. Such fine positioning is necessary not only for the semiconductor devices mentioned above, but also for various high-magnification optical devices such as electron microscopes, and by improving its accuracy, it is also necessary for cutting-edge technologies such as biotechnology and space development. This will greatly contribute to the development of the world.

Conventionally, a device shown in FIG. 11 has been proposed as such a fine positioning device. That is, FIG. 11 is a side view of a conventional fine positioning device.

In the figure, 1 is a support base, 2a and 2b are plate-shaped parallel springs fixed parallel to each other on the support base 1, and 3 is a parallel spring 2a, 2
This is a highly rigid fine movement table fixed on the top. Reference numeral 4 denotes a fine movement actuator mounted between the support base 1 and the fine movement table 3. This fine movement actuator 4 uses a piezoelectric element, an electromagnetic solenoid, etc., and by exciting it, a force is applied to the fine movement table 3 in the X-axis direction of the coordinate axis shown in the figure. Reference numeral 5 indicates a power source for the fine movement actuator 4.

Here, due to their structure, the parallel springs 2a and 2b have low rigidity in the X-axis direction, but have high rigidity in the Z-axis and y-axis directions (directions perpendicular to the paper), so the fine movement actuator is not excited. Then, the fine movement table 3 is displaced almost only in the X-axis direction, and almost no displacement occurs in other directions. Therefore, by exciting the fine movement actuator 4, the fine movement table 3 can be slightly displaced by a distance ε in the X-axis direction, as shown by the broken line in the figure.

Incidentally, although the fine movement table 3 is hardly displaced in any direction other than the X-axis direction, the fine movement table 3 is displaced in two axes directions (downward in the figure) due to the deformation of the parallel springs 2a and 2b as shown by the broken lines. do.

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

A fine positioning device that does not cause such lateral displacement has been proposed by the present applicant in Japanese Patent Application No. 60-46443. This will be explained using a diagram. Figure 12 fa), (b
) is a side view of the proposed micropositioning device. In the figure, 10. lla, llb are rigid parts, 14a+, 14ag
is the rigid body part 10. These are parallel flexible beams connected parallel to each other between lla. The parallel flexible beams 14a+, 14az are formed by through holes 12a formed in the rigid body part. 14b1
．． 14b.

are parallel flexible beams connected parallel to each other between rigid body parts 10 and 11b, and are formed by through holes 12b drilled in the rigid body parts. 16a and 16b are piezoelectric actuators, each having a through hole 12a.

It is mounted between the protruding parts from the rigid body part protruding into the inside of the rigid body part 12b. The configuration to the left of the center of the rigid body portion 10 constitutes a horizontal parallel deflection beam displacement machine 19a, and the configuration to the right constitutes a parallel deflection beam displacement mechanism 19b.

Here, the coordinate axes are determined as shown in the figure (the y-axis is perpendicular to the plane of the paper), and voltages are simultaneously applied to the piezoelectric actuators 16a and 16b to generate the same force f in the Z-axis direction. At this time, consider the displacement that occurs in one of the parallel flexible beam displacement mechanisms, for example, the parallel flexible beam displacement mechanism 19a. By applying a voltage to the piezoelectric actuator 16a, the rigid body portion 10 is pressed in the z-axis direction by a force f. For this reason, the parallel deflection beam 14a+ +
14 a z undergoes bending deformation in the same way as the parallel springs 2a and 2b shown in FIG. 11, and the rigid body part 1o is in FIG. 12)
It is displaced in two axial directions as shown in . At this time, if the other parallel deflection beam displacement mechanism 19b were not present, the above-mentioned lateral displacement would also occur at the same time, albeit extremely small, in the rigid body portion 10.

Furthermore, when considering the displacement that occurs in the other parallel flexible beam displacement mechanism 19b when the parallel flexible beam displacement mechanism 192 does not exist, the parallel flexible beam displacement mechanism 19b is located along the y-axis direction passing through the center of the rigid body part 10 (reference). Since the parallel deflection beam displacement mechanism 19a is configured plane-symmetrically with respect to the reference plane, when a force f which is plane-symmetrical with respect to the reference plane is applied, the rigid body part 10 is simultaneously displaced in the X-axis direction, as described above. The above lateral displacement occurs, and its magnitude and direction are determined by the parallel deflection beam displacement mechanism 1
It has plane symmetry with that of 93 with respect to the reference plane.

That is, regarding the above-mentioned lateral displacement, the lateral displacement that occurs in the parallel deflection beam displacement mechanism 19a occurs in the left direction in the figure for displacement in the X-axis direction, and counterclockwise in the figure for rotational displacement around the y-axis. Parallel deflection beam displacement mechanism 19a
The lateral displacement that occurs in the X-axis direction occurs rightward in the figure, and the rotational displacement around the y-axis occurs clockwise in the figure. The magnitude of each displacement in the X-axis direction and the magnitude of rotational displacement around the y-axis are equal. Therefore, the lateral displacements occurring in both cancel each other out.

As a result, due to the application of force f, only a slight increase in internal stress occurs in each of the parallel flexible beams 14a+, 14a, z, 14bt, and 14bz due to the elongation in the longitudinal direction, and the rigid body portion 10 only moves in the X-axis direction. produces a displacement (principal displacement) ε.

When the voltage applied to the piezoelectric actuators 16a, 16b is removed, each parallel flexible beam 14a+.

14az, 14b+, and 14bz return to their pre-deformed states, and the parallel deflection beam displacement mechanisms 193 and 19b are shown in Fig. 12ia.
The state returns to the state shown in l, and the displacement ε becomes O.

In this way, in the device shown in FIG.
This method can be implemented, and the accuracy of displacement can be dramatically improved.

The present applicant further proposed in the above-mentioned Japanese Patent Application No. 60-46443 a fine positioning device that generates a fine rotational displacement around one axis, which is different from the above-mentioned translational displacement. This will be explained using a diagram. Figure 13(a).

(bl is a side view of the proposed micro-positioning device producing rotational displacement. In Figs. 20. 21 a, 2 l
b is a rigid body part, 24a+, j4az, 24b+, 2
4bz is a radial deflection beam. each radial deflection beam 24a,
.

24az, 24bt, and 24bz extend radially along dashed-dotted lines t, +, t, and z with respect to the axis O that passes through the center of the rigid body part 20 and is perpendicular to the paper surface, and connects the adjacent rigid body parts. There is. Radial deflection beam 24a+.

24a2 is formed by drilling the through hole 22a,
Further, the radial deflection beams 24bl and 24bZ are formed by opening the through holes 22b. 26a.

26b is a piezoelectric actuator, and each through hole 2
2a and 22b between the protruding parts protruding from the rigid body part. The configuration on the left side of the axis O constitutes a radial flexure beam displacement mechanism 29a, and the configuration on the right side constitutes a radial flexure beam displacement mechanism 29b.

Now, apply a predetermined voltage to the piezoelectric actuators 26a and 26b at the same time to generate a force of the same magnitude in the tangential direction to the circle centered on the center axis 0. Then,
The left protrusion of the rigid body part 20 is a piezoelectric actuator 26a.
is pushed upward along the tangent line by the force generated in
The right protrusion of the rigid body part 20 is a piezoelectric actuator 26b.
is pushed downward along the tangent line by the force generated.

The rigid body part 20 has radial deflection beams 2 on both open body parts 21a and 21b.
4a+, 24az, 24t)+, and 24bz, and as a result of receiving the above force, the beam 24a undergoes radial flexure as shown in FIG. 13(b).

24az, 24b+, 24bz rigid body parts 21a, 21b
The part connected to is a straight line L extending radially from point O.
+, Lz, but the part connected to the rigid body part 20 is a straight line slightly deviated from the above-mentioned direct bit, +, t, z (
This straight line also extends radially from point 0. )L+
', Lx' causes a minute displacement. Therefore, the rigid body portion 20 rotates by a small angle δ clockwise in the figure. The magnitude of this rotational displacement δ is the radial deflection beam 24a, 24
az, 24bl.

Since it is determined by the bending rigidity of 24b2, if the force f is accurately controlled, the rotational displacement δ can also be controlled with the same accuracy.

When the voltage applied to the piezoelectric actuators 26a, 26b is removed, the radiating deflection beam 24a+.

24az, 24t) 1.24bz returns to the state before deformation, and the rotational displacement mechanism returns to the state shown in FIG. 13(a),
The displacement δ becomes 0.

Now, in the fine positioning device described above, in order to obtain desired displacement with high precision, 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 explained with reference to FIG. 14 for the apparatus shown in FIG. 11.

FIG. 14 is a system diagram of a conventional control device. In the figure, 6 is the same fine positioning device as shown in FIG. 11, and the same parts are given the same reference numerals. 7 is a mirror attached to the end face of the fine movement table 3 in the displacement direction. 30 is a laser length measuring device, which accurately measures minute displacements of the fine movement table 3. This laser length measuring device 30 has a laser head 31
, an interferometer 32) a receiver 33 and a pulse comparator 34. The laser head 31 is, for example, a dual-frequency H, -N laser head, which outputs laser beams with slightly different frequencies f, , fz, and outputs a signal ( fl
fz) is also output. The interferometer 32 sends only the laser beam of frequency f1 out of the laser beam output from the laser head 31 to the mirror 7. The receiver 33 outputs a signal calculated based on the frequency of the laser beam sent from the interferometer 32. The pulse comparator 34 adds the signal from the laser head 31 and the signal from the receiver 33, and outputs a signal based on this as a signal from the laser length measuring device 30.

35 is a signal converter that outputs a signal (■) corresponding to the target displacement measurement of the fine positioning device 6; 36 is a signal converter that converts the output of the laser length measuring device 30 into a corresponding signal V' and outputs the signal V';37; .38 is an adder, and 39 is a piezo amplifier.

The piezo amplifier 39 outputs a required voltage to the actuator 4.

The operation of the above control device will be explained. Each laser beam from the laser head 31 is input to an interferometer 32, and only the laser beam of frequency f is irradiated onto the mirror 7. At this time, when the fine movement table 3 is displaced, Doppler modulation occurs in the irradiated laser beam due to the Doppler effect, and the mirror 7
The frequency of the laser beam reflected from is (fl ±Δf). This reflected laser light passes through the interferometer 32 and is input to the receiver 33 together with the laser light of frequency f2, and the receiver 33 calculates (fz (fl ±Δf1)) based on the frequencies of these two laser lights. A signal is output according to the

On the other hand, the laser head 31 outputs a signal (fl-f) corresponding to the difference in the frequency of each laser beam, and inputs it to the pulse comparator 34 together with the signal from the receiver 33. ((fl
fz) fz-(r+±Δf1)) is executed, and as a result, a signal ±Δr is taken out. This signal ±Δf.

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 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 an adder 37, and the deviation Δ■ (Δv=v−v′) between the two is calculated.
Further, the adder 38 adds this deviation Δ■ and the output signal V of the signal converter 35. Output signal of adder 38 (■10ΔV)
is output to the piezo amplifier 39, and the piezo amplifier 39 generates a driving voltage (k (
V+ΔV)) is output.

With such a control means, a voltage is applied to the actuator 4 so that the deviation Δ■ becomes O in the end, thereby making it possible to accurately generate a desired displacement in the fine movement table 3. can.

Note that the displacement part (rigid part 10°20) also applies to the fine positioning device shown in FIGS. 12(a) and 13(a).
It is clear that the above control device can be applied by attaching a mirror to.

[Problem that the invention seeks to solve]

By the way, a laser length measuring device is used in the above control device, but this laser length measuring device has an extremely large volume and is expensive, so it is not realistic to install it for each fine positioning device. is impossible. therefore,
When using the excellent fine positioning device shown in FIG. 12(a) or FIG. 13(a), it is possible to obtain displacement with considerably high precision, but it is not necessarily easy to obtain displacement with even higher precision. There has been a problem in that the functions of the long-awaited fine positioning device cannot be fully utilized.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for a fine positioning device that can solve the problems of the prior art and perform highly accurate displacement control.

[Means for solving problems]

In order to achieve the above object, the present invention provides a fine positioning device in which flat plate structural units are symmetrically connected, a displacement detection means is provided at a predetermined location of each flat plate structural unit, and the target displacement amount of the fine positioning device is A displacement amount setting means is provided, and the displacement amount setting means outputs a value corresponding to the target displacement amount, and each of the output values and the desired displacement form determined by the displacement detection means are The voltage applied to each actuator provided in each flat plate structural unit is controlled by the control means so that the amount of displacement matches the amount of displacement and the amount of displacement of displacement forms other than the desired displacement form becomes 0. It is characterized by the following.

[Effect]

When a target displacement amount is set in the displacement amount setting means, a value corresponding to the set target displacement amount is outputted from the displacement amount setting means, and the actuator of each flat plate structure unit is driven in accordance with each of these values. As a result, the plate-shaped flexible beam is deflected and the fine positioning device is displaced, and the displacement is detected by the displacement detection means, thereby determining the amount of displacement due to the desired displacement form and the amount of displacement due to displacement forms other than the desired displacement form. Desired. Then, each flat plate is adjusted such that the amount of displacement according to the desired displacement form matches each displacement amount output from the displacement amount setting means, and so that the amount of displacement due to a displacement form other than the desired displacement form becomes O. The voltage applied to the actuator of the structural unit is controlled. As a result, the fine positioning device is displaced by the target displacement amount.

〔Example〕

Hereinafter, the present invention will be explained based on 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 explaining this control device, a fine positioning device in which the control device is used will be explained with reference to the drawings.

2(a) and 2(b) are side views of a fine positioning device according to an embodiment of the present invention. In the figures, the same parts as shown in FIG. 12(a) are given the same reference numerals. .

40a+, 40az, 40at, and 40an are the parallel flexible beams 14a in the parallel flexible beam displacement mechanism 19a.

Each rigid body part 10.14a2. This is a strain gauge attached to the connection part with lla. Also, 40b,, 40bz, 40
bt, 40b4 are parallel flexible beams 14bl, 14b in the parallel flexible beam displacement mechanism 19b.

Each rigid body part 10. This is a strain gauge attached to the connection part with llb. Each strain gauge changes its resistance value depending on the applied strain.

As described in the explanation of the operation of the device shown in FIGS. 12(a) and 12(bl), this fine positioning device deflects each of the parallel flexible beams 14a1 to 14b2 by applying a predetermined voltage to the piezoelectric actuators 16a and 16b. , which produces a predetermined translational displacement, which is proportional to the voltage applied to the piezoelectric actuators 16a, 16b, while each parallel flexible beam 14a.

When ~14b8 is deflected, strain occurs in each strain gauge and its resistance value changes. Therefore, if these strain gauges are configured into an appropriate electrical circuit, each parallel deflection beam 1
A strain amount of 4at to 14b2 can be detected.

By the way, in a symmetrical fine positioning device as shown in FIG. 2(a), the parallel deflection beam displacement mechanism 192.1
It is impossible to construct the parts 9b completely identically, and it is impossible to avoid variations in dimensions between corresponding parts of the two parts. Moreover, piezoelectric actuators 16a, 16b
There are also some differences in the characteristics. Therefore, even if the same voltage is applied to the piezoelectric actuators 15a and 16b, the fine positioning device does not perform translational displacement as shown in FIG. 12 (bl), but moves to either side as shown in FIG. (Note that this rotational displacement is extremely exaggerated. Also, the 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 15b, the amount of strain caused by the deflection of the parallel deflection beams 14a+ and 14az will be different from the amount of strain caused by the deflection of the parallel deflection beams 14b1 and 14b2.If both amounts of strain If they are equal, these amounts of strain 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 this embodiment, the parallel deflection beam displacement machine J1
The amount of strain due to translational displacement and the amount of strain due to rotational displacement of 19a and 19b are individually detected, and control is performed to obtain accurate displacement amounts based on the detected values.

Therefore, in this embodiment, a means for detecting these two amounts of strain is essential. This means will be explained using figures.

FIG. 3 (81, (b) is a circuit diagram of the distortion amount detection circuit. In each figure, 40a+, 40a, 40ax, 40aa
.

4Qbl, 4Qb2, 40bi, and 40b4 are strain gauges shown in FIG. 2(a), respectively. Reference numeral 41 indicates a bridge circuit for detecting the amount of strain due to translational displacement of the parallel deflection beam displacement mechanisms 19a, 19b, and 42 indicates a bridge circuit for detecting the amount of strain due to rotational displacement of the parallel deflection beam displacement mechanisms 19a, 19b. Each bridge circuit 41.
At 42, each strain gauge is connected as shown. B is a DC power supply.

Now, if a voltage is applied to the piezoelectric actuators 16a and 16b and a displacement as shown in FIG. 12(b) occurs, in the bridge circuit 41, the strain gauge 40az
, 40bl contract, and the strain gauges 40az and 40bz expand, their resistance values change accordingly, and the sum of these changes is output as the strain amount ε1.

In the bridge circuit 42, strain gauges 40aa,
40b and + are contracted, strain gauges 40ai and 40tz are expanded, and the amount of strain ε2 is output in such a manner that the amount of change in their resistance values is canceled. In the case of the state shown in FIG. 12(b), the amount of strain ε2 is 0, but as shown in FIG.
In the case of the state shown in , the distortion scene ε2 is not O because rotational displacement is included. In the following explanation, it is assumed that the strain amount ε2 in such a case is positive, and the strain amount ε2 for rotational displacement in the opposite direction is negative.

Here, a control device for a fine positioning device shown in FIG. 1 using such a strain amount detection means will be described below. In the figure, 16a and 16b are piezoelectric actuators, 19a and 1
9b is a parallel deflection beam displacement mechanism, 40a+ to 40a4,
40b+ to 40b< are strain gauges, which are the same as those shown in FIG. 2 (al).

45 is a displacement amount setter for setting the target displacement amount of the fine positioning device shown in FIG. A proportional value . This is performed for each displacement amount.The displacement amount setting device 45 stores a value V proportional to each measured strain amount for each displacement amount.The displacement amount setting device 45
When the target displacement measurement is input, the corresponding stored value (■) is extracted and output.

46a, 46b are adders, 47al, 47az
.

47b+ and 47bz are gain adjusters, 48a and 48b are integrators, and 49a and 49b are adders. Here, gain adjusters 47a+, 47az, 47b+.

41bt and integrators 48a, 48b are the adder 46a
, 46b, the magnitude of the feedback signal per unit time is changed, and the magnitude of the gain of the gain adjusters 47a, 48b is adjusted. This has the function of preventing hunting that occurs in the control system, and also allowing the displacement to quickly reach the target position without causing positional deviation. 50a.

Reference numeral 50b denotes an amplifier that amplifies the outputs of the adders 49a and 49b to a drive level for the piezoelectric actuator in proportion to the outputs thereof.

51 is a strain meter that includes a bridge circuit 41 and amplifies its output ε1 to a predetermined level of voltage;
The output of 1 is indicated by the value ■1.

Further, 52 is a strain meter that includes a bridge circuit 42 and amplifies its output ε2 to a predetermined level of voltage, and the output of this strain meter 52 is shown as a value V2. 54 is a display that displays the amount of displacement based on the output of the strain gauges 51 and 52.

Next, the operation of this embodiment will be explained. When a value is input and set to the displacement amount setting device 45 in order to displace the fine positioning device shown in FIG. 2(a) by a displacement i1L, the displacement amount setting device 4
5, the voltage ■ proportional to the amount of strain ε1 corresponding to the value
is output. This voltage ■ is applied to the adder 46a, gain adjusters 47a+, 47az+integrator 48a, and adder 49.
The signal is input to the amplifier 50a via a. Amplifier 50a generates a voltage proportional to this input signal and at a level suitable for driving piezoelectric actuator 16a, and applies it to piezoelectric actuator 16a. As a result, the parallel deflection beam 14a1.14az of the parallel deflection beam displacement mechanism 19a
is deflected, and the strain gauges 40a, ~40a
4 causes strain. Similarly, the voltage ■ outputted from the displacement amount setter 45 is amplified by the amplifier 50b, the piezoelectric actuator 16b is driven, and the parallel deflection beam displacement mechanism 19
The parallel deflection beams 14b+ and 14bz of b are deflected to produce strain in the strain gauges 40b+ to 40b4.

The strain gauge 51 includes strain gauges 40a, 40az.

40b and 40bz are the bridge circuit 4 shown in FIG.
As a result of the strain in these strain gauges, a strain amount ε1 corresponding to the translational displacement is detected, and this strain amount ε1 is amplified into a signal ■1 proportional to this, and from the strain gauge 51. Output. On the other hand, strain meter 5
2 has strain gauges 40 az, 40 a4+40
b3+ 40 b4. are connected to form a bridge circuit 42 shown in FIG. 3 (bl), a distortion amount ε corresponding to rotational displacement is detected, and an amplified signal V2 is output.

The signal from the strain meter 51 is input to the adders 46a and 46b, and is added to the signal ■ to obtain the deviation (■-v1) between the two. In addition, the signal 2 of the strain meter 52 is sent to the adders 46a and 4.
6b. That is, now the fine positioning device is
(In the state shown in bl, the output ε2 of the bridge circuit 42 shown in FIG. 3(b)) Therefore, the signal 2 becomes a positive value. In this case, since the displacement on the parallel flexible beam displacement mechanism 19a side is large and the displacement on the parallel flexible beam displacement mechanism 19b side is small, the voltage applied to the piezoelectric actuator 16a is decreased and the voltage applied to the piezoelectric actuator 16b is increased. control is necessary. And adder 46
The signal ■2 is subtracted in the adder 46b, and the signal ■2 is subtracted in the adder 46b.
is added. In the end, the output of the adder 46a becomes a value that decreases the displacement on the side of the parallel flexible beam displacement mechanism 19a and increases the displacement on the side of the parallel flexible beam displacement mechanism 19b.

The amplifiers 50a and 50b include an adder 49a.

49b, a value increased or decreased by the deviation from the target value V is input as a signal. By repeating this operation, the bridge circuit 4 is finally
The voltage v1 proportional to the output ε1 of 1 and the output voltage V of the displacement setter 45 match, and the output ε2 of the bridge circuit 42 becomes O, so that the target translational displacement can be obtained with high accuracy.

In addition, strain gauge 40 al+ 40 az+40
bl.

40bt constitutes a bridge circuit that detects rotational displacement, and strain gauges 40ai, 40a4, 401)+,
40b4 can also constitute a bridge circuit that detects translational displacement.

In this way, in this embodiment, strain gauges on the same side of the fine positioning device form bridge circuits, one bridge circuit detects translational displacement, and the other bridge circuit detects rotational displacement. Since feedback control is performed based on these detected values so that the translational displacement becomes the target value and the rotational displacement becomes O, highly accurate translational displacement can be obtained. Further, since the control system described above can be configured extremely small and inexpensively, it can be installed in each fine positioning device.

FIG. 4 is a block diagram of a control device for a fine positioning device according to another embodiment of the present invention. In this embodiment, for the fine positioning device shown in FIG. 13 (al), a control device is provided which generates only rotational displacement and obtains highly accurate rotational displacement. Before explaining the control device of this embodiment, the arrangement of the strain gauges and the strain amount detection circuit will be explained using diagrams. are given the same reference numerals and the explanation will be omitted.60
a.

608z is a strain gauge attached to the radial deflection beam 24a1, and 60a, 60a are the radial deflection beams 24a! Strain gauge affixed to, 60bl.

60 bg is a strain gauge attached to the radial deflection beam 24b2.

When a predetermined voltage is applied to the piezoelectric actuators 26a and 26b, each of the radial deflection beams 24a and 24b2 deflects,
A predetermined rotational displacement is produced. This amount of rotational displacement is proportional to the voltage applied to the piezoelectric actuators 26a, 26b. When each radial deflection beam 24a1-24b2 deflects, each strain gauge 60a1-60b! Strain occurs and its resistance value changes. Therefore, these strain gauges 60a
.

~60b2 for each radial deflection beam 24a1~24b
The amount of strain t can be detected.

By the way, even in this fine positioning device, it is normal that complete rotational displacement cannot be obtained for the same reason as stated in the explanation of the previous embodiment, and in the state of rotational displacement shown in FIG. Also, in this example, as in the previous example, the amount of strain due to rotational displacement and the translational displacement in the X-axis direction and the z-axis direction are often included. The amount of strain caused by the translational displacement is detected and the amount of strain caused by the translational displacement is controlled to be zero.
Shown in Figures (a) to (C).

FIGS. 6(a) to 6(C) are circuit diagrams of the distortion amount detection circuit. 6(a) shows a bridge circuit 61 that detects the amount of strain ε3 due to rotational displacement, and FIG. 6(a) shows a bridge circuit 62 that detects the amount of strain ε4 due to translational displacement in the X-axis direction, Furthermore, FIG. 6(C) shows a bridge circuit 6 that detects the amount of strain ε due to the translational displacement in the z-axis direction.
It is clear that each bridge circuit 61, 62, 63 can be constructed by attaching two strain gauges 60a to 60bt shown in Fig. 3.

Here, a control device for a fine positioning device according to this embodiment using the above-mentioned strain amount detection means will be explained. In FIG. 4, parts that are the same as those shown in FIG. 1 are given the same reference numerals and explanations will be omitted. However, the displacement amount setting device 45 is a setting device for setting the amount of rotational displacement.

26a and 26b are piezoelectric actuators shown in FIG. 5(a), and 29a and 29b are radial deflection beam displacement mechanisms shown in FIG. 5(a). 6 oal ”'60tz, 60J.

60b2 are strain gauges shown in FIG. 5(a). 65. 66 x and 66 z are the first
The strain gauge 65 corresponds to the strain gauges 51 and 52 shown in the figure, and the strain gauge 65 is connected to the bridge circuit 61 shown in Figure 6(a).
The strain gauge 66x includes a bridge circuit 62 shown in FIG. 6 (bl), and the strain gauge 66z includes a bridge circuit 63 shown in FIG. 6(C).

In this embodiment, an adder 46a, a gain adjuster 47a+,
47at, integrator 48a, adder 49a1 amplifier 50a
, piezoelectric actuator 26a, radial deflection beam displacement mechanism 2
9a1 strain gauge 60al~60a*+60b
Drive control of the radial deflection beam displacement mechanism 29a side is performed by a loop passing through strain gauges 65, 66x, and 66z, and an adder 46b and a gain adjuster 47.
b+, 47bz, integrator 48b, adder 49b, amplifier 50b, positive actuator 26b, radial flexure beam displacement mechanism 29b, strain gauge sob+, 6ot,, radial flexure beam displacement by loop passing through strain gauges 65° 66x, 66z Drive control on the mechanism 29b side is performed. With this control, the output V4 of the strain gauge 66x and the strain gauge 6
The value of the output V of the strain gauge 65 is set to 0, that is, the translational displacement in the X-axis direction and the z-axis direction included in the rotational displacement is removed, and at the same time, the output V3 of the strain gauge 65 is set to 0.
is made to match the output V of Since the operation of this embodiment is similar to that of the previous embodiment, detailed explanation will be omitted.

In this way, in this embodiment, the strain gauges attached to the radial deflection beams are used to detect the rotational displacement in the displacement amount, the bridge circuit to detect the translational displacement in the X-axis direction, and the bridge circuit to detect the translational displacement in the z-axis direction. A bridge circuit that detects displacement is used, and feedback control is performed so that the rotational displacement becomes the target value and at the same time each translational displacement becomes 0, so highly accurate rotational displacement can be obtained. or,
Since the control system described above can be constructed extremely compactly and inexpensively, it can be installed in each fine positioning device.

FIG. 7 is a perspective view of a fine positioning device to be controlled by a control device according to still another embodiment of the present invention. The positioning device is cut at the center to construct a single-piece fine positioning device, and these two single-piece fine positioning devices are connected by a highly rigid connecting plate 70. The same reference numerals are given to parts corresponding to the parts shown.

Even in the fine positioning device having such a configuration, as in the fine positioning device in each of the previous embodiments, it is difficult to rotate both the radial deflection beam displacement mechanisms 29a and 29b completely equally. It is clear that if the rotational displacements of the radial deflection beam displacement mechanisms 29a and 29b are not the same, the connecting plate 70 will not be completely rotationally displaced and tearing will occur.

Therefore, for this fine positioning device as well, the rotational displacement is controlled to the target value and at the same time the displacement due to tearing is controlled to be O, in accordance with the previous embodiments. The means for detecting the amount of distortion due to rotational displacement and torsional displacement required for this purpose will be explained with reference to the drawings.

FIGS. 8(a) and 8(b) are circuit diagrams of the distortion amount detection circuit. In each figure, 60 al ~ 60 at, 601) l
+60 bt.

is the strain gauge shown in FIG. 71 is a bridge circuit that detects the amount of strain ε6 due to the rotational displacement, and 72 is a bridge circuit that detects the amount of strain ε6 due to the I return.

The control device of the fine positioning device of this embodiment is almost the same as the control device of the previous embodiment shown in FIG. That is, the fourth
In the control device shown in the figure, strain gauges 65, 66x, 6
6z, a strain meter including a bridge circuit 71 and a strain meter including a bridge circuit 72 are provided, and the output signal of the former strain meter is directly input to adders 46a and 46b,
The output signal of the latter strain meter is input to adders 46a and 46b. The rest of the configuration is the same as the configuration of the device shown in FIG. Further, its operation is similar to that of the device shown in FIG.

As described above, in this embodiment, in a fine positioning device in which two single radial deflection beam displacement mechanisms are connected by a connecting plate, a bridge circuit that detects the rotational displacement component of the displacement amount and a bridge circuit that detects the tear displacement component are used. Since the circuit is used to perform feedback control so that the rotational displacement becomes the target value and the weeping displacement becomes 0 at the same time, the same effect as in the previous embodiment is achieved.

In the description of the above embodiment, the parallel flexible beam 14a+.

An example has been described in which the amount of deformation of 14az, 14b+, and 14bz is detected using a strain gauge. However, the amount of deformation can also be detected by other detection means. An example using this other detection means will be described below.

FIGS. 9(a) and 9(b) are side views of another fine positioning device to be controlled by the present invention. In FIG. 9fa), parts that are the same as those shown in FIG. 2(a) are given the same reference numerals and their explanations will be omitted. llc is a support part made of a rigid body,
Parallel flexible beams 14ax, 14 from rigid body parts 11a, 11b
bz and is configured to extend parallel to the bottom surface 10c of the rigid body section 10. 80a and 80b are capacitance type displacement detectors fixed to the support part 11c, and the upper end surface and the bottom surface 10c
Detect the interval δ between. Note that the capacitive displacement detectors soa and sob will be described later.

Now, when a predetermined voltage is applied to the piezoelectric actuators 16a, 16b, the parallel bending beams 14a1.14at, 14b
+, 14bz are deformed as shown in FIG. 9(a), and as a result, the bottom surface 10c of the rigid body portion 10 is also displaced upward in the figure.

Therefore, the interval δ also changes, and this changed interval is the difference between the capacitive displacement detector 80a.

80b.

Here, consider a case where the displacement includes a rotational displacement as shown in FIG.
The detection value of the capacitive displacement detector 80a on the a side is 61, and the capacitive displacement detector 8 on the parallel flexible beam displacement mechanism 19b side is 61.
Assuming that the detected value of 0b is δ, in the deformation shown in FIG. 2(b), the translational displacement is (δ, +δb)/2) and the rotational displacement is (δ).

-δ1)/2.

Therefore, in the control device shown in FIG.
80b, and in place of each strain gauge and each strain meter, a capacitive displacement detector 80 is provided.
a, 80 b and a calculation mechanism that calculates the translational displacement and rotational displacement described above, it is possible to perform control exactly the same as when using a strain gauge.

Figure 9(b) shows that the capacitive displacement detector is installed at the 9th position.
9 is a side view of a fine positioning device different from that shown in FIG. 9(a), and the same parts as shown in FIG. 9(a) are given the same reference numerals. Capacitive displacement detector 80a, 80
Holding parts 10a and 10 b protrude inward from the rigid body part 10 and hold the piezoelectric actuators 16a and 16b, respectively.
It is fixed on the top surface of b. Each of the capacitive displacement detectors 8Qa and 80b has parallel flexible beams 14a+ and 14, respectively.
parallel deflection beam 14a+,
When 14b+ deforms, a change in the interval δ between the two is detected.

This fine positioning device can also be applied to the control device shown in FIG. 1, like the one shown in FIG. 9 (al).

Next, such a capacitive displacement detector 80a.

The configuration of 80b and the outline of the detection circuit will be explained.

FIGS. 10(a) and 10(d) are a sectional view and a bottom view of the capacitive displacement detector, and FIG. 10(C) is a circuit diagram of the detection circuit. Hereinafter, only the capacitive displacement detector 80a will be described. In FIGS. 10(a) and 10(b), 80a1 is a cylindrical center electrode, and 803g is a cylindrical electrode centered on the center electrode 80a1. 80a3 is the center electrode 80a+
This is a dielectric material that exists between the cylindrical electrode 80a2 and the cylindrical electrode 80a2. The center electrode 80a1 and the cylindrical electrode 803t are configured so that their cross-sectional areas are equal.

Here, if the distance between the bottom surface of the capacitive displacement detector 80a and the surface facing it is δ, the cross-sectional areas of the center electrode 80a+ and the cylindrical electrode 80at are each S, and the permittivity of the dielectric is 8, then Center electrode 80a+ and cylindrical electrode 80az
The capacitance C1 between is expressed by the following equation.

C,=εS/δ Therefore, the interval δ can be detected by measuring the electrostatic amount C1 of the capacitive displacement detector 80a.

This capacitance C1 is detected by a detection circuit shown in FIG. 10(C). In FIG. 10(C), 81 is an oscillator, 82 is a capacitor providing a reference capacitance C7, 83 is an AC amplifier, 80a is the capacitance type displacement detector, and 84 is an AC
/DC converter, 85 is a DC amplifier, and 86 is a low-pass filter.

Here, when the signals of the predetermined frequency and predetermined voltage of the oscillator 81 are e and It becomes @z ' Cy / C@. This signal is converted to direct current by an AC/DC converter 84, span-adjusted and amplified by a DC amplifier 85, and shaped by a low-pass filter 86. Eventually, the signal e11 becomes ε S and is output as a detection signal with an interval δ. . That is, the interval δ can be detected by the capacitive displacement detector 80a.

In the description of each of the above embodiments, a control device for translational displacement in one direction and rotational displacement around one axis was explained, but it is also possible to control device for controlling translational displacement in multiple directions, rotational displacement around multiple axes, or both translational displacement and rotational displacement. It is clear that the present invention can also be applied to a fine positioning device that performs.

〔Effect of the invention〕

As described above, in the present invention, the amount of displacement of a desired displacement form is detected and the amount of displacement is made to match the target value, and at the same time, the amount of displacement of an undesired form of displacement is detected and feedback control is performed to set this as O. This makes it possible to obtain highly accurate displacement.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control device for a fine positioning device according to an embodiment of the present invention, and FIGS. 2(a) and 2(b) are side views of the fine positioning device that is controlled by the control device shown in FIG. , FIG. 3 (81, (b) is a circuit diagram of a strain amount detection circuit, FIG. 4 is a block diagram of a control device for a fine positioning device according to another embodiment of the present invention, and FIG. 5 (a), ( b) is a side view of the fine positioning device that is controlled by the control device shown in FIG. 4, FIGS. A perspective view of a fine positioning device to be controlled by a control device according to still another embodiment of the present invention, FIG. 8 (al), (bl is a circuit diagram of a strain amount detection circuit, and FIG. Side view of another fine positioning device used in the control device shown in FIG. 1, No. 10
Figures (a), (b), and (C) are respectively Figure 9+8)
, A cross-sectional view, a bottom view, and a detection circuit diagram of the capacitive displacement detector shown in (b), FIG. 11, and FIG. 12 (a). 13(b) and FIGS. 13(a) and 13(b) are side views of a conventional fine positioning device, and FIG. 14 is a system diagram of a control device of the conventional fine positioning device. 14a+, 14az, 14b1.14b2. ”...Parallel flexible beams, 16a, 16b, 26a, 26b...
・-Piezoelectric actuator, 19a, 19b...
Parallel deflection beam displacement mechanism, 24a1.24az, 24b+
, 24t) z... Radial deflection beam, 29a, 29
b...Radial deflection beam displacement mechanism, 40a+ ~4
0aa, 40b+ ~40b4, 60a+ ~60
aa, 60b+ ~6ob4...Strain gauge, 45...Displacement setting device, 46a, 4
6 b...Adder, 51.52.65.66
x, 66z...Strain meter, 80 a, 80
b...Capacitive displacement detector. (b) Shizu 3 diagram (a) (b) Congee 5 ward diagram 6 (C) Difference To diagram party 9 diagram (a) (b) (C) Nishiki 12 diagram (b) Figure 13

Claims (7)

[Claims] (1) In a fine positioning device that symmetrically connects flat plate structural units each having a plate-like flexible beam disposed facing each other between two rigid bodies and an actuator that applies a force between the rigid bodies, a predetermined position of each flat plate structural unit is provided. a displacement detecting means disposed at a location; a displacement setting means for setting a target displacement of the fine positioning device and outputting a value corresponding to the target displacement; and a means for determining a second displacement amount according to a displacement form other than the desired displacement form; and a means for determining a second displacement amount according to a displacement form other than the desired displacement form; 1. A control device for a fine positioning device, comprising: control means for controlling a voltage applied to the actuator so as to set a detected value to “0”. (2) A control device for a fine positioning device according to claim 1, wherein the flat plate structural unit is a parallel plate structural unit in which the plate-like flexible beams are arranged parallel to each other. (3) Control of the fine positioning device according to claim 1, wherein the flat plate structural unit is a radial flat plate structural unit in which the plate-like flexible beams are arranged radially with respect to a predetermined point. Device. (4) The control device for a fine positioning device according to claim 1, wherein the actuator is a laminated piezoelectric element. (5) The control device for a fine positioning device according to claim 1, wherein the displacement detection means is a strain gauge provided at a predetermined location of the plate-shaped flexible beam. (6) The fine positioning device according to claim 1, wherein the displacement detecting means is a capacitance type detector provided at a position facing the displacement portion of the fine positioning device. Control device. (7) A control device for a fine positioning device according to claim 1, wherein the control means includes a feedback control circuit.