JPH071453B2 - 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. In these devices, fine positioning on the order of sub-μm is necessary, and as the positioning accuracy improves, the degree of integration increases,
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 its precision, even in advanced technologies such as biotechnology and space development. Will greatly contribute to the development of.

Conventionally, an apparatus shown in FIG. 11 has been proposed as such a fine positioning apparatus. That is, FIG. 11 is a side view of a conventional fine positioning device. 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 displaced by a distance ε ₁ in the x-axis direction with a smile 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. 12 (a) and 12 (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 flexural beams 14
a ₁ and 14a ₂ are formed by through holes 12a formed in the rigid body portion.
Reference numerals 14b ₁ and 14b ₂ are parallel flexible 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. Reference numerals 16a and 16b denote piezoelectric actuators, which are mounted between the protruding portions from the rigid body portions protruding 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. 12 (b). At this time, if the other parallel flexural beam displacement mechanism 19b does not exist, the lateral displacement described above should occur at the same time in the rigid body 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, the parallel flexible beams 14a ₁ , 14a ₂ , 14b ₁ , 14b ₂ return to the state before deformation, and the parallel flexible beam displacement mechanisms 19a, 19b move to the first position. 1
Returning to the state shown in Fig. 2 (a), the displacement ε becomes zero.

As described above, in the device shown in FIG. 12 (a), 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. FIGS. 13 (a) and 13 (b) are side views of the proposed fine positioning device that causes rotational displacement. In the figure,
20, 21a and 21b are rigid bodies, and 24a ₁ , 24a ₂ , 24b ₁ and 24b ₂ are radial bending 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. 13 (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. 13 (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. 14 for the device shown in FIG.

FIG. 14 is a system diagram of a conventional control device. In the figure, 6 is
It is the same fine positioning device as that shown in FIG. 11, and the same reference numerals are given to the same parts. 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 FIG. 12 (a) and FIG. 13 (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. 12 (a) or FIG. 13 (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 object, the present invention provides a fine positioning device in which flat plate structural units each having a plate-shaped flexible beam and a rigid body, which are opposed to each other, are connected symmetrically to each other. In each of the flat plate structure units, displacement detecting means for detecting the displacement amount thereof and displacement amount setting means for setting a target displacement amount of the fine positioning device and outputting a value according to the target displacement amount A displacement amount extraction means for independently extracting displacement amounts of a desired displacement type and displacement amounts other than the desired displacement type based on the detection values of the displacement detection means, and the displacement amount setting Based on the deviation between the target displacement amount set in the means and the displacement amount of the desired displacement form extracted by the displacement extraction unit, and the displacement amount of the displacement form other than the desired displacement form. Te, characterized in that a control means for controlling a voltage applied to said actuator so as to eliminate the displacement amount and the deviation.

[Action]

When the target displacement amount is set in the displacement amount setting means, the displacement amount setting means outputs a value corresponding to the set target displacement amount, and the actuator of each flat plate structure unit is driven in accordance with these values. As a result, the plate-shaped flexible beam is deflected to displace the fine positioning device, and the displacement is detected by the displacement detection means, whereby the displacement due to the desired displacement form and the displacement due to the displacement form other than the desired displacement form are detected. Desired. Then, each flat plate is arranged so that the displacement amount due to the desired displacement form and each displacement amount output from the displacement amount setting means coincide with each other and the displacement amount due to the displacement form other than the desired displacement form becomes zero. 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 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. 12 (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.

This fine positioning device Figure 12 (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 amount of strain due to translational displacement of a and 19b and the amount of strain due to rotational displacement are individually detected, and control is performed to obtain an accurate amount of displacement based on this detected value. 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
1 is a bridge circuit for detecting the amount of strain due to translational displacement of the parallel flexible beam displacement mechanisms 19a, 19b, and 42 is a bridge circuit for detecting the amount of strain due to rotational displacement of the parallel flexible beam displacement mechanisms 19a, 19b. In each bridge circuit 41, 42, the strain gauges are connected as shown. B is a DC power supply.

Now, voltage is applied to the piezoelectric actuators 16a and 16b, and the first
2 If the displacement shown in FIG. 2 (b) occurs, the strain gauges 40a ₁ and 40b ₂ in the bridge circuit 41 contract,
The strain gauges 40a ₂ and 40b ₁ 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. In the bridge circuit 42,
Strain gauges 40a ₄ and 40a ₃ contract, strain gauges 40b ₃ and 40a ₄
Is extended, and the strain amount ε ₂ is output in a form in which the changes in the resistance values are canceled. In the case of the state shown in FIG. 12 (b), the strain amount ε ₂ is 0, but FIG. 2 (b)
In the case of the state shown in (1), the amount of strain ε ₂ is not 0 because the rotational displacement is included. In the following case in the description such strain amount epsilon ₂ positive, the rotational displacement amount of the strain amount epsilon ₂ in the reverse direction it is assumed to be negative.

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 determines the strain amount ε corresponding to the target displacement amount L.
A value V proportional to ₁ is output. That is, the output (strain amount) ε ₁ of the bridge circuit 41 when the displacement amount is obtained for a certain displacement amount is measured in advance for the fine positioning device, and this measurement is performed for each displacement amount. The displacement amount setter 45 stores a value V proportional to each measured strain amount for each displacement amount. Then, when the target displacement amount L is input, the displacement amount setter 45 stores the stored value V corresponding to this.
Output and output.

46a and 46b are adders, 47a ₁ , 47a ₂ , 47b ₁ and 47b ₂ are gain adjusters, 48a and 48b are integrators, and 49a and 49b are adders. Here, the gain adjusters 47a ₁ , 47a ₂ , 47b ₁ , 47b ₂ and the integrator 48
a and 48b are for changing the size of the feed back signal per unit time in a feed back control system using a deviation signal (described later) output from the adders 46a and 46b, and are for gain adjusters 47a _{1 to} 48b. By adjusting the magnitude of the gain, it has a function of preventing hunting that occurs in the control system, and preventing displacement and allowing the displacement to quickly reach the target position. 50a,
Reference numeral 50b is an amplifier that amplifies the outputs of the adders 49a and 49b in proportion to the outputs of the adders 49a and 49b to the drive level of the piezoelectric actuator.

A strain gauge 51 includes a bridge circuit 41 and amplifies its output ε ₁ to a voltage of a predetermined level. The output of the strain gauge 51 is indicated by a value V ₁ . Reference numeral 52 is a strain gauge that includes the bridge circuit 42 and amplifies its output ε ₂ to a voltage of a predetermined level. The output of the strain gauge 52 is indicated by a value V ₂ . Reference numeral 54 is a display device that displays the amount of displacement based on the outputs of the strain gauges 51 and 52.

Next, the operation of this embodiment will be described. When the value L is input to the displacement amount setter 45 to displace the fine positioning device shown in FIG. 2 (a) by the displacement amount L, the displacement amount setter 45 is proportional to the strain amount ε ₁ corresponding to the value L. Voltage V is output. This voltage V is added to the adder 46a and the gain adjusters 47a ₁ and 4
It is input to the amplifier 50a via 7a ₂ , the integrator 48a and the adder 49a. The amplifier 50a generates a voltage which is proportional to this input signal and has a level suitable for driving the piezoelectric actuator 16a, and applies this voltage to the piezoelectric actuator 16a.
As a result, the parallel flexible beam 14a of the parallel flexible beam displacement mechanism 19a is
₁ and 14a ₂ bend, and strain gauges 40a _{1 to} 40a ₄
Strain. Similarly, the voltage V output from the displacement amount setter 45 is amplified by the amplifier 50b, the piezoelectric actuator 16b is driven, and the parallel flexible beams 14b ₁ and 14b _{2 of} the parallel flexible beam displacement mechanism 19b are deflected and the strain gauge 40b ₁ Strain occurs at ~ 40b ₄ .

Strain gauges 40a ₁ , 40a ₂ , 40b ₁ and 40b ₂ are connected to the strain gauge 51 so as to form a bridge circuit 41 shown in FIG. 3 (a). A minute strain amount ε ₁ is detected, and this strain amount ε ₁ is amplified to a signal V ₁ proportional to this and output from the strain type 51. On the other hand, the strain gauge 52 has strain gauges 40a ₃ , 40a ₄ ,
40b ₃ and 40b ₄ are connected so as to form the bridge circuit 42 shown in FIG. 3B, the strain amount ε ₂ of the rotational displacement is detected, and the amplified signal V ₂ is output.

Strain gauge 51 signals of the adders 46a, is input to the 46b, it is added to the signal V both of the deviation (V-V ₁₎ is obtained. or,
The signal V ₂ of the strain gauge 52 is input to the adders 46a and 46b. That is, when the fine positioning device is now in the state shown in FIG. 2 (b), the output ε of the bridge circuit 42 shown in FIG. 3 (b).
_2. Therefore, the signal V ₂ has a positive value. In this case, since the displacement on the side of the parallel flexible beam displacement mechanism 19a is large and the displacement on the side of the parallel flexible beam displacement mechanism 19b is small, the voltage applied to the piezoelectric actuator 16a is reduced, and the piezoelectric actuator 16b is reduced.
It is necessary to control the direction of increasing the voltage applied to. Then, the adder 46a subtracts the signal V ₂ and the adder 46b adds the signal V ₂ . After all, the output of the adder 46a has a value that reduces 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.

To the amplifiers 50a and 50b, a value obtained by increasing or decreasing the target value V by the deviation is input as a signal by the adders 49a and 49b. Then, by repeating such operations, the voltage proportional to the output ε ₁ of the bridge circuit 41 is finally obtained.
V ₁ and the output voltage V of the displacement amount setter 45 match, and the output ε ₂ of the bridge circuit 42 becomes 0, so that the target translational displacement can be obtained with high accuracy.

The strain gauges 40a ₁ , 40a ₂ , 40b ₁ , 40b ₂ constitute a bridge circuit for detecting the rotational displacement,
It is also possible to configure a bridge circuit that detects a translational displacement amount by using a ₃ , 40a ₄ , 40b ₃ , and 40b ₄ .

Thus, in this embodiment, the strain gauges on the same side of the fine positioning device constitute the respective bridge circuits, one of the bridge circuits detects the translational displacement, and the other bridge circuit detects the rotational displacement. Since the feed back control is performed so that the translational displacement amount becomes the target value and the rotational displacement amount becomes 0 based on these detected values, it is possible to obtain the translational displacement with high accuracy. Further, since the control system can be constructed extremely small and inexpensive, it can be installed in each fine positioning device.

FIG. 4 is a block diagram of a control device for a fine positioning apparatus according to another embodiment of the present invention. In this embodiment,
It is intended to provide a control device for generating only a rotational displacement and obtaining a highly accurate rotational displacement with respect to the fine positioning device shown in FIG. 13 (a). For this reason,
Before explaining the control device of the present embodiment, the arrangement of the strain gauges and the strain amount detection circuit will be described with reference to the drawings.
In FIGS. 5 (a) and 5 (b), the same parts as those shown in FIG. 11 (a) are designated by the same reference numerals and the description thereof will be omitted. 60a ₁ , 60a ₂
Is a strain gauge affixed to the radiating flexible beam 24a ₁ , 60a ₃ , 6
0a ₄ is a strain gauge attached to the radiating flexible beam 24a ₂ , 60b
Reference numerals ₁ and 60b ₂ are strain gauges attached to the radiating flexible beam 24b ₂ .

The piezoelectric actuator 26a, when a predetermined voltage is applied to 26b, each radiating flexure beam 24a ₁ ~24b ₂ is deflected, resulting in a predetermined rotational displacement. This rotational displacement is calculated by the piezoelectric actuator 26a,
It is proportional to the voltage applied to 26b. Each radiation deflection beams 24a ₁ ~2
When 4b ₂ is bent, strain is generated in each strain gauge 60a _{1 to} 60b ₂ and its resistance value changes. Therefore, using these strain gauges 60a _{1 to} 60b ₂ , each radial flexible beam 24a _{1 to} 24b
The strain amount of b ₂ can be detected.

By the way, even in this fine positioning apparatus, it is usual that a complete rotational displacement cannot be obtained for the same reason as described in the description of the embodiment, and the state of rotational displacement shown in FIG. 5 (b) is obtained. Also, in many cases, translational displacements in the x-axis direction and the z-axis direction are included. Therefore, also in the present embodiment, similarly to the previous embodiment, the control for detecting the strain amount due to the rotational displacement and the strain amount due to the translational displacement in the x-axis direction and the z-axis direction and setting the strain amount due to the translational displacement to 0 is performed. Run. A sixth means for detecting the amount of strain necessary for this is
It shows in figure (a)-(c).

FIGS. 6A to 6C are circuit diagrams of the strain amount detection circuit. 6A shows a bridge circuit 61 for detecting the strain amount ε ₃ due to the rotational displacement, and FIG. 6B shows a bridge circuit 62 for detecting the strain amount ε ₄ due to the translational displacement in the x-axis direction. 6C shows a bridge circuit 63 for detecting the strain amount ε ₅ due to the translational change in the z-axis direction. It is obvious that each of the bridge circuits 61, 62 and 63 can be constructed by sticking _two strain gauges 60a _{1 to} 60b ₂ to each other.

Here, the control device of the fine positioning apparatus of the present embodiment using the above strain amount detecting means will be described. In FIG. 4, the same parts as those shown in FIG. However, the displacement amount setting device 45 is a setting device that sets the rotational displacement amount. Reference numerals 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). 60a _{1 to} 60b ₄ , 60b ₁ and 60b ₂ are strain gauges shown in FIG. 5 (a). Reference numerals 65, 66x, 66z are strain gauges corresponding to the strain gauges 51, 52 shown in FIG. 1, and the strain gauge 65 is a bridge circuit shown in FIG. 6 (a).
61, the strain gauge 66x includes the bridge circuit 62 shown in FIG. 6 (b), and the strain gauge 66z includes the bridge circuit 63 shown in FIG. 6 (c).

In this embodiment, the adder 46a, gain adjusters 47a ₁ and 47a ₂ , integrator 48a, adder 49a, amplifier 50a, piezoelectric actuator 2
6a, Radial flexible beam displacement mechanism 29a, Strain gauge 60a _{1 to} 60a
₄ , 60b ₁ , 60b ₂ , strain gauges 65, 66x, 66z are radiatively flexed beam displacement mechanism 29a side drive control is performed by a loop,
Further, the adder 46b, the gain adjusters 47b ₁ and 47b ₂ , the integrator 48b, the adder 49b, the amplifier 50b, the pressure division actuator 26b, the radial flexible beam displacement mechanism 29b, the strain gauges 60b ₁ and 60b ₂ , the strain gauge.
Drive control on the side of the radiating flexible beam displacement mechanism 29b is performed by a loop passing through 65, 66x, 66z. By this control, the values of the output V ₄ of the strain gauge 66x and the output V ₅ of the strain gauge 66z are set to 0, that is, the translational displacements in the x-axis direction and the z-axis direction included in the rotational displacement are removed, and at the same time, The output V ₃ of the strain gauge 65 is made to match the output V of the displacement amount setter 45. Since the operation of this embodiment is similar to the operation of the previous embodiment, detailed description will be omitted.

As described above, in this embodiment, the strain gauge attached to the radial bending beam is used to detect the rotational displacement during the displacement amount, the bridge circuit for detecting the x-axis translational displacement, and the z-axis translational displacement. Since the bridge circuit for detecting the displacement amount is used to perform the feed back control so that the rotational displacement amount becomes the target value and each translational displacement amount becomes 0 at the same time, the rotational displacement with high accuracy can be obtained. or,
Since the control system can be constructed extremely small and inexpensive, it can be installed in each fine positioning device.

FIG. 7 is a perspective view of a fine positioning device to be controlled by the control device according to still another embodiment of the present invention. The fine positioning device in the present embodiment constitutes a single-type fine positioning device by cutting the symmetrical fine-positioning device shown in FIG. 5 (a) at the center, and these two single-type fine positioning devices are made rigid. It is configured to be connected by a high connecting plate 70. In the figure, parts corresponding to the parts shown in FIG.

Even in the fine positioning device having such a configuration, it is difficult to rotationally displace both of the radial bending beam displacement mechanisms 29a and 29b in the same manner as the fine positioning device in each of the above embodiments. Then, the radial flexible beam displacement mechanism 29
If the rotational displacements of a and 29b are not the same, it is obvious that the connecting plate 70 is not completely rotationally displaced and twists.

Therefore, also with respect to this fine positioning apparatus, the rotational displacement is controlled to a target value and the displacement due to the twist is controlled to 0 at the same time, in accordance with the respective embodiments described above. The strain amount detecting means for the rotational displacement and the displacement due to the twist required for this purpose will be described with reference to the drawings.

8A and 8B are circuit diagrams of the strain amount detection circuit. In the _{figures, 60a 1 ~60a 4, 60b 1} , 60b 2, is a strain gauge shown in Figure 7. Reference numeral 71 is a bridge circuit for detecting the strain amount ε ₆ for the rotational displacement, and 72 is a bridge circuit for detecting the strain amount ε ₇ for the displacement due to the twist.

The control device of the fine positioning apparatus 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, in place of the strain gauges 65, 66x, 66z, a strain gauge including the bridge circuit 71 and a strain gauge including the bridge circuit 72 are provided, and the output signal of the former strain gauge (bridge circuit 71) is Input to the adders 46a and 46b with a sign "-", and the output signal of the strain gauge of the latter (bridge circuit 72) is a sign "-" to the adder 46a and the adder 46b.
Enter with the sign "+". The other structure is the same as that of the apparatus shown in FIG. The operation is also similar to that of the device shown in FIG.

As described above, in the present embodiment, in the fine positioning device in which the two radial bending beam displacement mechanisms are connected by the connecting plate, the bridge circuit for detecting the rotational displacement and the bridge circuit for detecting the torsional displacement in the displacement amount. The feed back control is performed so that the rotational displacement amount becomes the target value and the torsional displacement amount becomes 0 at the same time. Therefore, the same effect as the previous embodiment can be obtained.

In the description of the above embodiment, the parallel flexible beams 14a ₁ , 14a ₂ , 14b ₁ , 1
An example of detecting the deformation amount of 4b ₂ using a strain gauge was 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.

9 (a) and 9 (b) are side views of another fine positioning apparatus to be controlled by the present invention. In FIG. 9 (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 formed of a rigid body, and is configured by extending from the rigid body portions 11a and 11b in parallel with the parallel bending beams 14a ₂ and 14b ₂ and the bottom surface 10c of the rigid body portion 10. Reference numerals 80a and 80b 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 80a and 80b 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 the changed interval is the capacitance type displacement detectors 80a, 80b.
Detected by.

Here, consider a case where the displacement includes a rotational displacement as shown in FIG. In this case, the parallel flexible beam displacement mechanism 19a
When the detection value of the capacitance type displacement detector 80a on the side is δa and the detection value of the capacitance type displacement detector 80b on the side of the parallel flexible beam displacement mechanism 19b is δb, the modification shown in FIG. 2 (b) In, it is considered that the translational displacement is (δa + δb) / 2 and the rotational displacement is (δa−δb) / 2.

Therefore, in the control device shown in FIG. 1, the output V of the displacement amount setter 45 is determined in advance so as to correspond to the capacitance type displacement detectors 80a and 80b, and each strain gauge and each strain gauge is used. Instead of using the capacitance type displacement detectors 80a and 80b and the arithmetic mechanism that calculates the translational displacement amount and the rotational displacement amount, the same control as in the case of using the strain gauge can be performed.

In FIG. 9 (b), the mounting position of the capacitance type displacement detector is the 9th position.
It is a side view of a fine positioning device different from that shown in FIG. 9A, and the same portions as those shown in FIG. 9A are denoted by the same reference numerals. Capacitive displacement detectors 80a and 80b 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 capacitance type displacement detectors 80a and 80b 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. 9 (a).

Next, the configuration of such capacitance type displacement detectors 80a and 80b and the outline of the detection circuit will be described. Figure 10 (a),
(D) is a sectional view and bottom view of the capacitance type displacement detector,
FIG. 10 (c) is a circuit diagram of the detection circuit. Hereinafter, only the capacitance type displacement detector 80a will be described. In FIGS. 10A and 10B, 80a ₁ is a cylindrical center electrode, and 80a ₂ is a cylindrical electrode centered on the center electrode 80a ₁ . 80a ₃ is a dielectric that exists between the center electrode 80a ₁ and the cylindrical electrode 80a ₂ .
The center electrode 80a ₁ and the cylindrical electrode 80a ₂ are configured so that their cross sectional areas are equal.

Here, the distance between the bottom surface of this capacitance type displacement detector 80a and the surface facing it is δ, the center electrode 80a ₁ and the cylindrical electrode
When the cross-sectional area of 80a ₂ is S and the dielectric constant of the dielectric is ε, the capacitance Ca between the central electrode 80a ₁ and the cylindrical electrode 80a ₂ is expressed by the following equation.

Ca = εS / δ Therefore, the capacitance Ca of this capacitance type displacement detector 80a
The interval δ can be detected by measuring

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

Here, the signal of the predetermined frequency and the predetermined voltage of the oscillator 81
and EEx, when amplifying a capacitance Ca of the electrostatic capacitance type displacement detector 80a in AC amplifier 83, whose output ea becomes _{ea = -eex · C Y / Ca} . This signal is converted to direct current by the AC / DC converter 84, span-adjusted and amplified by the DC amplifier 85, shaped by the low-pass filter 86, and finally the signal ea is And is output as a detection signal of the interval δ. That is, the interval δ can be detected by the capacitance type displacement detector 80a.

In the description of each of the above embodiments, the control device for translational displacement in one direction and rotational displacement about one axis has been described, but translational displacement in multiple directions, rotational displacement about multiple axes, or both translational displacement and rotational displacement. It is obvious that the present invention can be applied to a fine positioning device that performs

[Effects of the Invention] As described above, in the present invention, the displacement amount of the desired displacement form is detected and matched with the target value, and at the same time, the undesired displacement form displacement amount is detected and set to 0. Since the feed back control is performed, it is possible to obtain a highly accurate displacement.

[Brief description of drawings]

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 which is a control target of the control device shown in FIG. 3 (a) and 3 (b) are circuit diagrams of a strain amount detecting circuit, FIG. 4 is a block diagram of a control device of a fine positioning apparatus according to another embodiment of the present invention, and FIG. 5 (a), (B) is a side view of a fine positioning device which is a control target of the control device shown in FIG. 4, (a), (b) and (c) of FIG. 6 are circuit diagrams of a strain amount detection circuit, and FIG. A perspective view of a fine positioning device which is a control target of a control device according to still another embodiment of the present invention, FIGS. 8 (a) and 8 (b) are circuit diagrams of a strain amount detection circuit, FIG. 9 (a), (B) is a side view of another fine positioning device used in the control device shown in FIG. 1, and FIGS. 10 (a), (b) and (c) are it. It is Figure 9 (a),
A sectional view, a bottom view and a detection circuit diagram of the capacitance type displacement detector shown in (b) are shown in FIG. 11, FIG. 12 (a), (b) and FIG. 13 (a), (b). FIG. 14 is a side view of the fine positioning device, and FIG. 14 is a system diagram of a control device of the conventional fine positioning device. 14a ₁ , 14a ₂ , 14b ₁ , 14b ₂ , ... parallel flexural beams, 16a, 16b, 26a,
26b …… Piezoelectric actuator, 19a, 19b …… Parallel flexible beam displacement mechanism, 24a ₁ , 24a ₂ , 24b ₁ , 24b ₂ …… Radial flexible beam, 29
a, 29b …… Radial flexible beam displacement mechanism, 40a ₁ 〜 40a ₄ , 40b ₁ 〜 40
b ₄ , 60a _{1 to} 60a ₄ , 60b _{1 to} 60b ₄ …… Strain gauge, 45 …… Displacement setting device, 46a, 46b …… Adder, 51,52,65,66x, 66z…
… Strain gauges, 80a, 80b… Capacitive displacement detectors.

 ─────────────────────────────────────────────────── ─── 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. Displacement detection means arranged for each of the displacement detection means, displacement amount setting means for setting a target displacement amount of the fine positioning apparatus and outputting a value according to the target displacement amount, and each displacement detection means. Displacement amount extraction means for independently extracting the displacement amount of the desired displacement form and the displacement amount of the displacement form other than the desired displacement form based on the detection value of the target displacement, and the target displacement set in the displacement amount setting means. Based on the deviation between the amount and the displacement amount of the desired displacement form extracted by the displacement extraction means, and the displacement amount of the displacement form other than the desired displacement form, this displacement amount and the previous Fine positioning apparatus characterized in that a control means for controlling a voltage applied to the actuator to eliminate the deviation. 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.