JPH10332860A - Support device of slider - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent bending of a guide by the weight of a slider and the guide and causing displacement in the slider in the height direction. SOLUTION: To eliminate a displacement in the height direction at the position of the slider 21, an external force is applied to the guide 22. The strength of the force applied actually to the guide is detected and control quantity is feedback-controlled so as to adjust to a target value. A force generation means is arranged in the vicinity of the both ends of the guide 22 and these forces are independently controlled. The calculated results of the strength of force necessary at each position are stored in a table. The actual displacement is detected by using a straight master and the displacement is corrected. To generate necessary forces, a bob is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support device for a sliding body, and can be applied to, for example, a mechanism for holding a measuring head portion in an ultra-precision flatness measuring device so as to be movable in a predetermined axial direction.

[0002]

2. Description of the Related Art For example, in an ultra-precision flatness measuring instrument, X and Y axes orthogonal to the Z axis are detected while detecting the distance between the measuring object and the Z-axis direction (generally the vertical direction) using a minute displacement meter. By moving at least one of the minute displacement meter and the measurement target in the direction, the flatness of the measurement surface is identified from the change in the detection distance.

[0003] In this type of apparatus, a small displacement meter is generally connected to an X.
A slider for holding the micro displacement meter and a guide for slidably guiding the slider along the X-axis are provided to hold the slider in a freely movable state in the axial direction. Since the guide is often supported at both ends due to its structure, the guide is bent by its own weight or the load of the slider and the displacement meter. Even a small amount of this kind of bending can have a serious adverse effect in the field of ultra-precision measurement and ultra-precision machining.

For this reason, conventionally, for example, Japanese Patent Publication No. 6-31
As disclosed in Japanese Patent Publication No. 736 and Japanese Patent Publication No. 6-44051, the guide material is devised or is formed in a hollow body to increase the rigidity of the guide and reduce the amount of deflection. On the other hand, as shown in FIG. 23, when the straight ruler is supported at two points of the fulcrum 1 and the fulcrum 2 and the fulcrum position is determined so that the coefficient of a / L becomes 0.5228, the bending at the center of the straight ruler is reduced. It is well known that this does not occur (edited by the Japan Society of Mechanical Engineers: Mechanical Engineering Handbook, B2 Machining Science / Machining Equipment, p197), which is convenient when only the fulcrum is used.

[0005]

However, even if the material and structure of the guide are devised as in the prior art, adverse effects due to the deflection of the guide remain. For example, Japanese Patent Publication No. 6-31736
In the example shown in the above publication, when alumina ceramic is used as the material, the maximum bending amount is 0.2 μm in the hollow linear guide mechanism having a stroke of 240 mm at both ends.
m, the change in the amount of deflection according to the position of the slider is 0.1 μm
However, even this amount of deflection has a great effect on ultra-precision machining or ultra-precision measurement with an accuracy on the order of nanometers.

[0008] If the principle of the straight ruler shown in FIG. 23 is applied to an apparatus for supporting a sliding body in an ultra-precision measuring instrument or an ultra-precision processing machine, the bending of the guide can be greatly reduced. However, according to this principle, a guide having a length approximately twice as long as the distance between the fulcrums actually used for moving the slider is required, and the material cost and the space occupied by the guide are wasteful, so that the practicality is low. .

[0007] Even if this principle is used, the effect of bending cannot be reduced sufficiently. That is, static deflection caused by the weight of the guide can be reduced by the principle of FIG.
The bending due to the weight of the slider cannot be dealt with because the amount of bending of each part of the guide dynamically changes with its movement. The present invention suppresses the increase in size and cost of the device in the above-described sliding member support device, and reduces the static deflection of the guide due to its own weight and the dynamic deflection of the guide caused by the movement of the slider. An object of the present invention is to reduce both of them to further improve the positioning accuracy of the slider.

[0008]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, there is provided a guide member having at least two points at its both ends or at the vicinity thereof,
A position detecting means for detecting a sliding position of the slider member on the guide member; and A force generating means for applying a pressing force or a pulling force to an end of the member or in the vicinity thereof, and a position detecting means for correcting a positional displacement of the slider member due to the bending of the guide member, according to position information detected by the position detecting means. Correction force control means for providing the determined control amount to the force generation means is provided.

According to a second aspect of the present invention, in the sliding body support device according to the first aspect, the force generating means includes a force detecting means for detecting a magnitude of a force actually applied to the guide member. Wherein the correction force control means includes feedback control means for automatically correcting a control amount given to the force generation means according to the magnitude of the force detected by the force detection means.

According to a third aspect of the present invention, in the sliding device supporting device according to the first aspect, the force generating means includes a first force generating means disposed at one end of the guide member or in the vicinity thereof. A second force generating unit disposed at or near the other end of the guide member, wherein the correction force control unit performs a correction based on the position information detected by the position detection unit and a predetermined evaluation function. And a control amount determining means for independently determining both a control amount to be applied to the first force generating means and a control amount to be applied to the second force generating means.

According to a fourth aspect of the present invention, in the sliding body support device according to the first aspect, the correction force control means sets the target value information of the control amount at each position obtained in advance by calculation to the position. It is characterized in that it comprises a control amount storage means for holding it in association with it. According to a fifth aspect of the present invention, in the sliding device supporting device according to the first aspect, the position reference member is disposed in parallel with the axis of the guide member along a sliding path of the slider member. A distance detecting unit disposed on the slider member so as to face the position reference member and detecting a distance between the slider member and an opposing surface of the position reference member; and the correction force control unit includes the distance detection unit. A control amount determining unit that determines a control amount to be applied to the force generating unit based on the distance detected by the unit and the position information detected by the position detecting unit.

According to a sixth aspect of the present invention, in the sliding device supporting device according to the first aspect, a distance detecting means disposed on the slider member in a state facing the surface on which the object to be measured is disposed. A detachable position reference member disposed along a sliding path of the slider member, in parallel with an axis of the guide member, and opposed to a detection surface of the distance detection means; A force control means, in a state where the position reference member is mounted, a target value of a control amount to be given to the force generation means based on the distance detected by the distance detection means and position information detected by the position detection means. Is determined for each position, and a control amount storage means for storing the determined target value of the control amount in association with the position of the slider member is included.

According to a seventh aspect of the present invention, in the sliding device supporting apparatus according to the first aspect, the force generating means applies a constant tensile force to an end of the guide member, and And a variable force generating means for applying a variable force to the end portion or the vicinity thereof.

(Operation) For example, as shown in FIG.
And the guide 3 whose both ends are supported at two points of the fulcrum 2 and
When the slider 4 supported by the guide 3 moves (slides) in the X-axis direction while being guided by the guide 3, the slider 4
Is displaced with respect to its reference position (the axial position of the guide 3 when there is no bending), and the displacement amount (δ1,
δ2) changes according to the position (x1, x2) of the slider 4 in the X direction. That is, the weight of the guide 3 and the slider 4 causes the slider 4 to bend, and the distribution of the load applied to the guide 3 changes as the slider 4 moves.
The bending shape and the bending amount of the guide 3 dynamically change.

Therefore, as shown in FIG. 4, if bending moments M1 and M2 are applied to both ends of the guide 3 in a direction opposite to the bending, the bending of the guide 3 caused by the weight of the guide 3 and the slider 4 is corrected. Can be returned to the reference position. Note that the same correction can be performed only by applying a force to one end of the guide 3. For example, as shown in FIG. 5, the fulcrums 1 and 2 are arranged slightly inside the both ends of the guide 3 (L> a), and the pressure P _{1 is} applied to the upper end of one end of the guide 3 and the pressure P ₂ is applied to the upper end of the other end. In addition, a moment in the direction in which the correcting force acts is generated in the guide 3.

Since the magnitude of the force required to eliminate the displacement of the slider 4 in the Z direction changes according to the position of the slider 4 in the X direction, it is essential to detect the position of the slider 4 in the X direction. According to the first aspect of the present invention, the pressing force or the pulling force of the force generating means is controlled by a control amount determined according to the sliding direction position of the slider member detected by the position detecting means. Therefore, the bending of the guide member is corrected by the moment generated in the guide member by this force. Then, at least at the position of the slider member, its Z-direction position displacement can be corrected to zero.

(Effect of the Invention of Claim 2) For example, when a pressing force is generated using a piezoelectric actuator as the force generating means, when a certain voltage is applied to the piezoelectric actuator, a constant displacement is generated in the piezoelectric actuator, The force generated by this displacement is applied to the guide member. However, when the column or the column and the guide member are deformed by this force, the force applied from the piezoelectric actuator to the guide member changes. Therefore, the control amount given to the force generating means and the magnitude of the force actually applied to the guide member do not always have a one-to-one correspondence.

According to the second aspect, the magnitude of the force actually applied to the guide member is detected by the force detection means, and the control amount given to the force generation means is corrected according to the detected value. Can be made to correspond to the value required to correct the force. (Operation of the invention according to claim 3) If the generation source of the force applied to the guide member in order to eliminate the displacement of the slider member is provided at only one place, the position on the guide member where the slider member is located Even if there is no displacement, the maximum value of the magnitude of the force required for the correction becomes very large, the force generating means becomes large, and the cost also rises significantly.

According to a third aspect of the present invention, the first force generating means and the second force generating means arranged at different positions are used, and the magnitudes of the forces generated by the first and second force generating means are independently determined based on a predetermined evaluation function. To decide. If the distribution of the force generated by the first force generation means and the force generated by the second force generation means is appropriate, the position of the slider member is relatively small regardless of the position in the movement range on the guide member. The deflection of the slider member can be corrected by force.

(Operation of the Invention of Claim 4) When calculating the control amount to be applied to the force generating means for correcting the deflection of the guide member, complicated calculations may be required. Therefore,
If the calculation is performed every time the slider member moves, the calculation takes a long time, so that the moving speed of the slider member may be limited.

According to the present invention, the target value information of the control amount at each position obtained in advance by calculation can be held in the control amount storage means in association with the position, so that the deflection of the guide member is actually corrected. Since the target value of the control amount at each position can be read out from the control amount storage means and immediately obtained, and no complicated calculation is required, the moving speed of the slider member is not restricted.

According to the fifth aspect of the present invention, the displacement amount of the slider member in the Z direction due to the bending of the guide member can be directly detected by using the position reference member and the distance detecting means. For this reason, the error between the grasped flexure amount and the actual flexure amount is smaller than in the case where the flexure amount is grasped by calculation, and more accurate correction of the guide member is realized.

The shape of the surface of the position reference member is not limited to a plane. If the surface of the position reference member is curved, it is possible to not only correct the deflection of the guide member due to weight, but also to positively apply the deflection to the guide member and move the slider member parallel to the curved surface of the position reference member. it can.

That is, when the surface of the inspection object is formed in a shape conforming to a predetermined reference curved surface, the position reference member is made to conform to the reference curved surface, so that the slider member is moved along the reference curved surface. Is moved, and a change in distance between the measuring object (a minute displacement meter) and the inspection object is measured by a measuring instrument (a minute displacement meter) disposed on the slider member, whereby the flatness of the surface of the inspection object relative to the reference curved surface is detected. .

(Operation of the invention according to claim 6) As in claim 5, the displacement amount of the slider member in the Z direction is directly detected. However, the position reference member is detachable since the distance detecting means used for inspecting the measurement object is also used for detecting the Z-direction displacement of the slider member. Then, before the measurement is started, control information necessary for correction is stored in the control amount storage unit.

That is, the position reference member is mounted at a predetermined position, the slider is moved (scanned) from one end to the other end of the movement range, and the distance detected by the distance detection means at each position and the position detection means A target value of the control amount is determined based on the detected position, and the target value is written in the control amount storage unit in association with the position. After this is completed, the position reference member is removed.

(Function of the Invention of Claim 7) The magnitude of the displacement of the slider member in the Z direction changes in accordance with the position of the slider member in the sliding direction. (Negative direction with respect to the axis). That is, in order to correct the displacement of the slider member in the Z direction, a force greater than a certain value must always be applied regardless of the position of the slider member in the sliding direction.

In the present invention, a constant tensile force is always applied to the guide member by using a weight, and the insufficient force is applied to the guide member by the variable force generating means. Therefore, the magnitude of the force to be generated by the variable force generating means is smaller than when no weight is present, which helps to reduce the cost of the force generating means.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) This embodiment corresponds to claims 1, 2, 3 and 4. FIG. 1 shows the appearance of the mechanism of the ultra-precision flatness measuring instrument. The base platen 10 is made of granite so as not to be easily affected by a change in environmental temperature, and is supported by an air spring type vibration damping mechanism 11 to suppress the influence of external vibration. This basic surface plate 10
Above, a Y-axis moving mechanism 12 for moving the object to be measured in the Y-axis direction, and an X-axis moving mechanism 14 for moving the micro displacement gauge 13 as a measuring means in the X-axis direction orthogonal to the Y-axis. It is configured.

The Y-axis moving mechanism 12 includes a slider 15 slidable in the Y-axis direction and a guide 16 for guiding the slider 15 along the Y-axis. The guide 16 is made of alumina ceramics in order to increase the rigidity. In order to reduce the sliding resistance, air is circulated through the gap between the slider 15 and the guide 16 so that the slider 15 is slightly lifted from the guide 16.

The guide 16 has a base 17 made of a low thermal expansion alloy.
And is fixed on the base platen 10 via a base plate. Slider 1
An alignment surface plate 18 is provided on 5. The object to be measured is placed on the alignment platen 18. At the time of measurement, it is necessary to move the slider 15 while finely and smoothly accelerating and decelerating according to the measurement pitch. Therefore, a drive mechanism including a high-precision ball screw mechanism and an AC servomotor (not shown) is connected to the slider 15. .

The X-axis moving mechanism 14 is configured so as to straddle the Y-axis moving mechanism 12, and holds the minute displacement meter 13 and
A slider 21 slidable in the axial direction and a guide 22 for guiding the slider 21 along the X axis are provided. The guide 22 is made of alumina ceramics, and the vicinity of both ends thereof is supported by columns 23 and 24. The columns 23 and 24 are made of granite. In order to reduce the sliding resistance, the slider 2
Air is circulated in the gap between the guide 1 and the guide 22 so that the slider 21 is slightly lifted from the guide 22.

The minute displacement meter 13 is mounted on a mounting portion 25 provided on a side surface of the slider 21. Mounting part 25
Is provided with an adjustment mechanism (not shown) for adjusting the position of the minute displacement meter 13 in the height direction (Z direction) according to the height of the measurement object. At the time of measurement, it is necessary to read the data output from the minute displacement meter 13 while moving the minute displacement meter 13 in the X-axis direction at a constant speed within the measurement range, and to minimize the influence of vibration and the like caused by the driving mechanism. For this purpose, a drive mechanism (not shown) composed of an AC linear servomotor having no mechanical connection is provided as a moving mechanism for the slider 21.

In this example, the slider 15 of the Y-axis moving mechanism 12 and the slider 21 of the X-axis moving mechanism 14 are both 3
It has a movement stroke of 00 mm. The main part of the X-axis moving mechanism 14 shown in FIG. 1 is enlarged and shown in FIG. As shown in FIG. 2, the guide 22 has a support 2 near its one end 22a.
3 is located in the concave portion 23a, and the vicinity of the other end 22b is
In the recess 24a. The guide 22 is supported at two points in the X direction by the protrusion 23b formed on the support 23 and the protrusion 24b formed on the support 24. The distance in the X direction from one end 22a to the protrusion 23b;
The distance in the X direction from b to the protrusion 24b is set to the same L1.

The guide 22 is formed as a hollow body having a rectangular cross section, and its dimensions are 0.08 m in the Y-axis direction and 0.12 m in the Z-axis direction.
m, the X-axis direction is 1.0 from one end 22a to the other end 22b.
m, and the distance between the protrusions 23b and 24b is 0.8 m. Protrusions 23b and 24b support Y
It has a length of about 0.1 m in the axial direction. Guide 22
The piezoelectric actuator 31 and the load cell 32 are arranged without any gap between the upper end surface of one end 22a of the guide 22 and the inner wall surface 23c of the support column 23, and the upper end surface of the other end 22b of the guide 22 and the inner wall surface 24c of the support column 24 are provided. Between them, the piezoelectric actuator 33 and the load cell 34 are overlapped and arranged without any gap.

The piezoelectric actuators 31 and 33 are provided for applying a pressing force in the Z direction to the one end 22a and the other end 22b, respectively. The load cells 32 and 34 apply the magnitude of the force applied to the one end 22a and the other end 22b. It is provided to detect the height. In order to detect the position of the slider 21 in the X direction, a position detector 35 is provided inside the slider 21.
Is provided. The position detector 35 is a reflection type optical sensor whose detection surface is directed to the guide 22. At a position facing the detection surface of the position detector 35 on the guide 22,
A linear scale 36 is formed.

The linear scale 36 is an optical mark in which light portions and dark portions are alternately arranged like a bar code at a fixed minute interval. When the slider 21 moves along the X-axis, every time the slider 21 moves by a certain minute distance, the position detector 35 detects the movement and outputs one pulse signal as an electric position signal Sp. By calculating the number of pulses of the position signal Sp, the relative movement distance of the slider 21 from the reference position in the X direction, that is, the position can be grasped.

Since the linear scale does not exist outside the predetermined X-direction movement range (in this example, between the projections 23b and 24b), the position signal Sp does not appear even if the slider 21 moves outside this range. . Therefore, the slider 21
The position at which the presence / absence of the position signal Sp switches when moves is regarded as the start point (reference position) or end point of the movement range.

The signal S1 output from the load cell 32, the signal S2 output from the load cell 34, the position signal Sp, and the output signal S3 of the micro displacement meter 13 are input to the control unit 100. The piezoelectric actuators 31 and 33 are controlled by signals S4 and S5 from the control unit 100, respectively. The drive mechanism (not shown) of the slider 21 is also controlled by the control unit 100.

The control unit 100 is constructed by mounting a general interface such as a driver circuit, a sensor amplifier, an A / D converter and a special software program for control on a commercially available 32-bit personal computer. . In this example, the bending of the guide 22 is corrected for the X-axis moving mechanism 14, but the correction is not performed for the guide 16 of the Y-axis moving mechanism 12. Therefore, a detailed description of the Y-axis moving mechanism 12 is omitted.

Next, the principle of correcting the Z-direction displacement of the minute displacement meter 13 due to the bending of the guide 22 of the X-axis moving mechanism 14 will be described. FIG. 6 (M1) shows a guide 3 bending deformation model based on the weights of the guide 3 and the slider 4 when the guide 3 is supported at two fulcrums 1 and 2. In FIG. 6, W
s is a concentrated load [N] corresponding to the weight of the slider 4, Wg
Indicates a distributed load [N / m] corresponding to the weight of the guide 3 per unit length. Further, L is the length from one end of the guide 3 to the other end [m], L ₁ is the length from the fulcrum 1 and 2 to the end surface [m], L ₂ represents the length between the fulcrum [m].

Since the rule of superposition can be applied to the model of FIG. 6 (M1), this can be decomposed into two models (M1a) and (M1b) shown in FIG. (M1a) is a model with only distributed loads, and (M1b) is a model with only concentrated loads. Here, assuming that E is Young's modulus (longitudinal elastic modulus) [N / m ² ] and I is the second moment of area [m ⁴ ], the Z direction at the position x (distance from the fulcrum 1) in the model (M1a) The displacement Z _1a is represented by the following first equation. The Z-direction displacement Z _1b at the position x in the model (M1b) is represented by the following second equation. Further Z-direction displacement Z ₁ at position x in the model (M1) is represented by the third equation shown below.

(Equation 1) FIG. 8 shows an example of the calculation result of the Z-direction displacement Z _1b at the position x in the model (M1b). C0, C1 and C in FIG.
2 are L ₁ = 0, L ₁ = 0.1 and L ₁ = 0.2, respectively.
It was calculated under the condition of [m]. Also, L ₂ = 0.8 [m],
The material of guide 3 is alumina ceramics and its density is 3
980 [Kg / m ³ ], Young's modulus is 4120 [GP
a], and the weight of the slider 4 was calculated as 145 [N].

On the other hand, when the forces P ₁ and P ₂ are applied to one end and the other end of the guide 3 from above, respectively, a bending deformation model of the guide 3 due to these forces is shown in FIG. 7 (M2). Then, in this model (M2), Z-direction displacement Z ₂ at position x on the guide 3 can be expressed by the equation 4 below.

(Equation 2) Therefore, if the control is performed so that “Z ₁ = Z ₂ ” is satisfied, the displacement in the Z direction at the position of the slider 4 becomes zero. "Z ₁ =
Under the condition of “Z ₂ ”, from the first to fourth formulas,
The following fifth equation is established.

(Equation 3) When the conditions of the following equations (6), (7) and (8) are applied, the above-mentioned equation (5) is transformed into the following equation (9).

(Equation 4) a · P ₁ + b · P ₂ = c (9) That is, if the forces P ₁ and P ₂ satisfying the above ninth equation are applied, the displacement of the slider 4 in the Z direction due to the deflection of the guide 3 becomes zero. Can be. Here, the combination of forces P _1, P ₂ satisfying the ninth equation is different exists, Intuitively, force P _1,
It is considered that the combination that minimizes the sum of P ₂ and satisfies the ninth formula is optimal. That is, a combination of P ₁ and P ₂ that minimizes A represented by A = P ₁ + P ₂ may be obtained. By transforming the ninth equation, P ₂ = (c−aP ₁ ) / b
Therefore, the following Expression 10 holds.

A = P1 ((b−a) / b) + (c / b) (10) It can be seen from the above equation (10) that there is no minimum value of A. That is, the tenth equation cannot be used as an evaluation function for obtaining a combination of P ₁ and P ₂ . Thus, as an example, an evaluation function that minimizes the sum of the squares of P ₁ and P ₂ and satisfies the ninth formula is considered. That is, since the following equations (11) and (12) are obtained, (dA / d
If P ₁ = 0), a force that minimizes A is required.

(Equation 5) That is, the following Expressions 13 and 14 for obtaining an appropriate magnitude of force are obtained from Expression 12. P ₁ = a · c / (a ² + b ² ) (13) P ₂ = b · c / (a ² + b ² ) (14) The magnitude of the force P ₁ obtained from the equation (13). P1d and 14th
The size P2d force P ₂ obtained from the formula shown in Figure 10. That is, if the forces P ₁ and P ₂ applied as shown in FIG. 10 are changed according to the position in the X direction, the displacement of the slider 4 becomes zero, and the accuracy of flatness measurement and the like is improved.

FIG. 12 shows the displacement in the Z direction at each position of the guide 3 when the force obtained by the equations (13) and (14) is applied to the guide 3 when the position x of the slider 4 is 0.2. Show.
According to FIG. 12, the displacement at the position of the slider (x = 0.2) is certainly zero. Various evaluation functions other than the above can be considered as an evaluation function for obtaining an appropriate combination of forces. For example, an evaluation function for finding a combination of forces that minimizes the product of P ₁ and P ₂ may be used. The size P of the evaluation of the force P ₁ determined based on a function magnitude P1a and power P ₂
2a is shown in FIG.

When the position of the slider 4 is x = 0.2 and the forces P1a and P2a shown in FIG.
FIG. 11 shows the Z-direction displacement at each position of the guide 3. FIG.
Even at 1, the displacement at the slider position (x = 0.2) is certainly 0. Next, the configuration and operation for automatically correcting the Z-direction displacement at the position of the slider 21 in the apparatus shown in FIGS. 1 and 2 will be described. FIG. 13 shows the configuration of this control system.

The correction force tables 113 and 1 shown in FIG.
Reference numeral 14 denotes a RAM (read / write memory) mounted on the control unit 100, and the contents thereof are updated as needed by the correction force calculation processing 115. This processing is a part of the software processing executed by the microcomputer on the control unit 100. In practice, the calculations of the above-described equations (13) and (14) are executed for each of various positions (x), and the results of the respective calculations are obtained. (P1d, P2d) is stored in the memory address associated with the position.

The data (P1d, P2d) written in the correction force tables 113 and 114 are read by giving position (x) information as a memory address.
Actually, the output value of the position counter 111 that counts the number of pulses of the position signal Sp is equal to the correction force tables 113 and 114.
, The magnitude of the force (P1d, P2d) to be applied to the guide 22 at each position is constantly output from the correction force tables 113 and 114.

The count value of the position counter 111 is cleared by the reference position detection processing when the position signal Sp does not appear for a predetermined time or more, so that the count value indicates the distance from the reference position, that is, the position. The correction force table 1
13 and 114 may be constituted by ROMs (read-only memories). However, if the weight of the minute displacement meter 13 changes due to replacement, the contents of the correction force tables 113 and 114 must be changed. The versatility is higher when using.

Value P output from correction force table 113
A voltage corresponding to 1d is applied to the piezoelectric actuator 31, and a voltage corresponding to the value P2d output from the correction force table 114 is applied to the piezoelectric actuator 33. However, when a displacement corresponding to the applied voltage occurs in the piezoelectric actuators 31 and 33 and a force corresponding to the displacement is generated,
The columns 23 and 24 or the columns and the guide 22 are deformed, and as a result, the force applied to the guide 22 by the piezoelectric actuators 31 and 33 changes. Therefore, there is no one-to-one correspondence between the voltage applied to the piezoelectric actuators 31 and 33 and the magnitude of the force actually applied to the guide 22 by the voltage.

Therefore, in this example, a feedback control system is configured to control the piezoelectric actuators 31 and 33 so that the forces corresponding to the target force magnitudes P1d and P2d are applied to the piezoelectric actuators 31 and 33, respectively. doing. That is, the difference between the target value P1d and the magnitude of the actual force (S1) detected by the load cell 32 is calculated by subtracter 1
It is obtained at 17 and input to a PI (proportional, integral) controller 119. An output corresponding to this input and a predetermined control gain is output from the PI controller 119 and applied to the piezoelectric actuator 31 via the driver 121.

Similarly, the difference between the target value P2d and the actual force magnitude (S2) detected by the load cell 34 is calculated by the subtractor 1
16 and input to the PI (proportional, integral) controller 118. An output corresponding to this input and a predetermined control gain is output from the PI controller 118 and applied to the piezoelectric actuator 33 via the driver 120. Note that the position information output by the position counter 111 is
It is also used for positioning control when the X-ray is driven in the X-axis direction, and for grasping the X-direction position when measuring the measurement object.

When actually measuring the flatness of the object to be measured, first, the object to be measured is arranged on the alignment plate 18 by hand, and the position of the object to be measured and the minute displacement meter 13 are aligned. Is carried out. In response to the predetermined measurement start operation, the control unit 100 sets the correction force table 113, 1
After the correct data obtained by the correction force calculation processing 115 is written to the slider 14, the slider 15 of the Y-axis moving mechanism 12 and the slider 21 of the X-axis moving mechanism 14 are respectively positioned at predetermined scanning start positions (generally, one end of the moving range). I do.

Then, the slider 21 is moved at a constant speed in the X-axis direction. While the slider 21 is moving, the output data of the minute displacement meter 13 is sampled at regular time intervals,
It is stored in a memory on the control unit 100. When the slider 21 moves from one end to the other end of the movement range, the slider 21 is returned to one end, and at the same time, the Y-axis moving mechanism 12
Is controlled to move the position of the slider 15 by a predetermined minute distance. Then, the slider 21 is moved again in the X-axis direction at a constant speed.

By repeating this operation, distance data at each position on the XY plane parallel to the surface of the object to be measured is obtained. The flatness of the surface is determined from the change in the distance data. (Second Embodiment) This embodiment corresponds to claims 1, 2, 3 and 5.

Here, the same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. FIG. 14 is an enlarged view of a main part of the X-axis moving mechanism 14. Referring to FIG. 14, a displacement detector 41 is provided on a slider 21. The displacement detector 41 has a detection surface 41a facing upward, and a straight master 42 is installed at a position facing the detection surface 41a.

The straight master 42 is a straight, plate-like member precisely machined from a highly rigid material, both ends of which are supported by columns 23 and 24, and positioned in parallel with the axis (X) of the guide 22. Have been. In particular, a surface of the straight master 42 facing the displacement detector 41 maintains a high degree of parallelism with the guide 22. Displacement detector 4
1 detects the distance between it and the straight master 42. When the guide 22 bends due to the weight, the distance detected by the displacement detector 41 changes. Accordingly, the displacement of the slider 21 in the Z direction due to the bending can be obtained by the signal S6 output from the displacement detector 41.

The control unit 200 is the same hardware as the control unit 100 of FIG. 2, but the software program executed by the control unit 200 is slightly changed. FIG. 15 shows the configuration of a control system for automatically correcting the displacement of the slider 21 in the Z direction due to bending. When the slider 21 is near the fulcrum (reference position), the amount of displacement in the Z direction is zero.

The distance signal S6 output from the displacement detector 41 is held in the latch 131 by using the clear signal for the position counter 111 output in the reference position detection processing 112, and the output of the latch 131 and the distance signal And the difference between S6 and S6 is output by subtractor 132 as signal S7. This signal S7 corresponds to the amount of displacement of the slider 21 in the Z direction.

That is, the value of the signal S7 is equal to Z _{1 of} the third equation.
Is equivalent to However, since the value of the signal S7 is an actual deviation that does not include a calculation error, it is highly likely that the value is more accurate.
In the correction force calculation process 133, the same calculation as in the case of the correction force calculation process 115 in FIG. 13 is performed using the value of the signal S7 instead of the displacement Z1, and the magnitudes of the forces P1d and P2 are calculated.
Find d. Further, since the calculation is simpler than the correction force calculation processing 115, the correction force table is omitted, the calculation is performed each time the position in the X direction changes, and the result is directly input to P1.
d, P2d.

If necessary, the straight master 42
May be formed into a predetermined curved surface. That is, when the surface of the measurement target is formed into a curved surface, the flatness with respect to the reference curved surface can be detected by matching the straight master 42 to the shape of the reference surface of the curved surface. (Third Embodiment) This embodiment corresponds to claims 1, 2, 3, 4, and 6.

Here, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted.
FIG. 17 is an enlarged view of a main part of the X-axis moving mechanism 14.
As in the second embodiment, also in this embodiment,
The straight master 51 is used to detect the displacement of the slider 21 in the Z direction. In this example, the straight master 51 includes a minute displacement meter 13 provided for measuring an object to be measured and an alignment platen. 18 is arranged.

The straight master 51 has both ends supported by columns 23 and 24, but is detachable. That is, since the single minute displacement meter 13 is used for both measurement of the measurement target placed on the alignment plate 18 and detection of the straight master 51, the measurement is not hindered when measuring the measurement target. Thus, the straight master 51 is detached.

The control unit 300 is the same hardware as the control unit 100 of FIG. 2, but the software program to be executed is slightly modified. FIG. 16 shows the configuration of a control system for automatically correcting the displacement of the slider 21 in the Z direction due to bending. As in FIG. 13, correction force tables 113 and 114 are provided, and as in FIG. 15, a latch 131 and a subtractor 132 are provided. The correction force calculation processing 141 is the same as the correction force calculation processing 133 in FIG. 15 except for the timing at which the calculation is performed and the result of the calculation in the correction force tables 113 and 1.
14 is different.

In this example, before the measurement is started, the straight master 51 is installed, the actual displacement of the slider 21 in the Z direction due to the deflection of the guide 22 is detected by the minute displacement meter 13, and the minute displacement meter 13 is detected. The correction force is calculated while moving at a constant speed in the X direction, and the calculation result is written into the correction force tables 113 and 114. When a predetermined pre-scanning instruction is generated based on the operation of the operator, the scanning control processing 1
By 42, the linear motor 143 for driving the slider 21 of the X-axis moving mechanism is controlled, and the slider 21 moves in the X direction at a constant speed that is slower than the time of measurement. The correction force calculation processing 141 is also executed in response to the pre-scanning instruction.

(Fourth Embodiment) In this embodiment,
This is a modification of the first embodiment, and corresponds to claims 1, claim 2, claim 3, and claim 4. The components of this embodiment are the same as those of the first embodiment. As shown in FIG. 18, the positions of the projections 23b and 24b and the positions of the piezoelectric actuators 31 and 33 and the load cells 32 and 34 are interchanged. Only the configuration is different. That is, in this embodiment, the positions of the piezoelectric actuators 31 and 33 that apply a force are located inside the protrusions 23b and 24b that are fulcrums.

Since the positions where the forces are applied are different, the magnitudes P1d, P1d of the forces to be generated by the piezoelectric actuators 31, 33
Although 2d is different, it can be calculated and obtained basically by the same method as in the first embodiment. (Fifth Embodiment) This embodiment is a modification of the first embodiment.
This corresponds to claim 4.

FIG. 19 is an enlarged view of a main part of the X-axis moving mechanism 14. Referring to FIG. 19, both ends of the guide 22 are supported by protrusions 23b and 24b. The means for applying a force to the guide 22 is significantly different from the first embodiment. That is, at one end 22a of the guide 22, the wire 64 connected to the upper portion 22c is wound by the DC servo motor 63 via the pulley 61, and at the other end 22b of the guide 22, it is connected to the upper portion 22d. The wire 68 is wound by a DC servo motor 67 via a pulley 65.

That is, by applying tensile forces P3 and P4 to one end 22a and the other end 22b of the guide 22, deflection of the guide 22 due to the weight of the guide 22 and the slider 21 is corrected. Load cells 62 and 66 are provided for detecting actual tensile forces P3 and P4. Load cell 62
Is disposed between a shaft that supports the pulley 61 and a member (a part of the support column 23) that supports the pulley 61 in a vertically movable manner. The load cell 66 connects the shaft that supports the pulley 65 and the shaft in the vertical direction. It is arranged between a member (a part of the column 24) that supports it movably.

Therefore, the control unit 100 controls the DC servo motor 63 so that the magnitude of the force detected by the load cell 62 becomes the target value, and the magnitude of the force detected by the load cell 66 becomes the target value. The DC servo motor 67 is controlled as described above. (Sixth Embodiment) This embodiment is a modification of the fifth embodiment, and is described in claim 1, claim 2, claim 3, or claim 3.
This corresponds to claims 4 and 7.

FIG. 20 is an enlarged view of a main part of the X-axis moving mechanism 14. Note that the same components as those in the fifth embodiment are denoted by the same reference numerals. Referring to FIG. 20, a weight 71 having a predetermined weight is mounted in the middle of a wire 64 connecting one end 22a of the guide 22 and the DC servo motor 63, and the other end 22b of the guide 22 is connected to the DC servo motor. Also in the middle of the wire 68 connecting the 67 and
A weight 72 having the same weight as the weight 71 is attached.

Because of the necessity of using the weights 71, 72, the DC servo motors 63, 67 are connected to the pulleys 61, 6
5 is arranged below. For example, P1 shown in FIG.
As in d and P2d, the force to be applied to correct the deflection of the guide 22 is the same in any direction regardless of the position of the slider 21 between the fulcrums. Of the size. In order to generate such a force, a relatively large and expensive drive source (here, DC servo motors 63 and 37) is required. But,
By using the weights 71, 72 and the drive source together, the load on the drive source is reduced, and the cost is reduced.

In each of the embodiments described above, the case where the guide 22 is supported at two points in the X direction has been described. For example, as shown in FIGS. 21 and 22, one end of the guide 22 is fixed. When the other end of the guide 22 or its vicinity is supported by one fulcrum 81 or 82, the force P1 is applied to eliminate the Z-direction displacement due to the deflection at the position of the slider 21. can do.

In any of the embodiments described above, the reference position specified by the presence or absence of a pulse signal indicating the amount of movement is used to obtain the absolute position of the slider 21 in the X direction. This method is merely an example. For example, a non-contact limit switch is used to determine the limit position of the moving range and the reference position for scanning, and the absolute position of the slider 21 is determined based on these positions. Is also good.

[0075]

【The invention's effect】

(Effect of Claim 1) The displacement of the slider member due to the bending of the guide member is automatically corrected by the force generated by the force generating means. And the measurement accuracy is surely improved.

(Effect of Claim 2) Even when the guide member is deformed by applying a force, the force applied to the guide member is controlled so as not to deviate from the target value, so that the displacement of the slider member due to the bending of the guide member Can be more reliably corrected. (Effect of Claim 3) If the distribution of the force generated by the first force generating means and the force generated by the second force generating means is appropriate,
Regardless of the position of the slider member in the movement range on the guide member, the deflection of the slider member can be corrected with a relatively small force. Therefore, the force generating means can be miniaturized, which contributes to cost reduction.

(Effect of Claim 4) Even if the calculation for obtaining the control amount is extremely complicated and takes a long time to execute the process, the control amount storage means must be stored in advance when performing the actual measurement. Since the control amount can be easily determined by using the information stored in the slider, the moving speed of the slider member is not limited during the measurement.

(Effect of Claim 5) Since the displacement is corrected on the basis of the actually detected displacement amount, the influence of a calculation error is reduced. Also, the calculation process is simplified. (Effect of Claim 6) Compared with Claim 5, there is no need to add a special distance detecting means, and the cost can be reduced.

(Effect of Claim 7) Since a constant force is always applied using the weight, the force to be generated by the variable force generating means is relatively small, which is effective in reducing the cost of the force generating means.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a mechanism of an ultra-precision flatness measuring device.

FIG. 2 is a block diagram showing a main part of the X-axis moving mechanism 12 in an enlarged manner.

FIG. 3 is a schematic diagram showing deflection of a sliding-body supporting device due to weight;

FIG. 4 is a schematic view showing the principle of correcting the deflection of the guide.

FIG. 5 is a schematic view showing the principle of correcting the deflection of the guide.

FIG. 6 is a schematic view showing a bending deformation model of a guide.

FIG. 7 is a schematic view showing a model for correcting deflection of a guide.

FIG. 8 is a graph showing an example of a position of a slider and a displacement in a Z direction.

FIG. 9 is a graph showing an example of a force required to correct a displacement of a slider.

FIG. 10 is a graph showing an example of a force required to correct a displacement of a slider.

FIG. 11 is a graph showing displacement of each part of the guide when a predetermined correcting force is applied.

FIG. 12 is a graph showing the displacement of each part of the guide when a predetermined correcting force is applied.

FIG. 13 is a block diagram showing a configuration of a control system for automatically correcting the displacement of the slider.

FIG. 14 is a block diagram showing a main part of the X-axis moving mechanism 12 in an enlarged manner.

FIG. 15 is a block diagram showing a configuration of a control system for automatically correcting the displacement of the slider.

FIG. 16 is a block diagram showing a configuration of a control system for automatically correcting the displacement of the slider.

FIG. 17 is a block diagram showing a main part of the X-axis moving mechanism 12 in an enlarged manner.

FIG. 18 is an enlarged block diagram showing a main part of the X-axis moving mechanism 12.

FIG. 19 is a block diagram showing a main part of the X-axis moving mechanism 12 in an enlarged manner.

FIG. 20 is a block diagram showing a main part of the X-axis moving mechanism 12 in an enlarged manner.

FIG. 21 is a front view schematically showing a guide support structure.

FIG. 22 is a front view schematically showing a guide support structure.

FIG. 23 is a schematic view showing a straightedge of a known technique.

[Explanation of symbols]

 Reference Signs List 10 base surface plate 11 air spring type vibration isolation mechanism 12 Y-axis movement mechanism 13 minute displacement meter 14 X-axis movement mechanism 15, 21 slider 1622 guide 17 base 18 alignment surface plate 23, 24 column 25 mounting part 22a one end 22b other end 23a , 24a recess 23b, 24b protrusion 31, 33 piezoelectric actuator 32, 34 load cell 35 position detector 36 linear scale 41 displacement detector 42, 51 straight master 61, 65 pulley 62, 66 load cell 63, 67 DC servo motor 64, 68 wire 71, 72 Weight 81, 82 Support point 100, 200, 300 Control unit 111 Position counter 112 Reference position detection processing 113, 114 Correction force table 115, 133, 141 Correction force calculation processing 116, 117, 132 Subtractor 118, 19 PI control 120 and 121 driver 131 latch 142 scanning control

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshimitsu Matsuhashi 239 Shimohirama, Saiwai-ku, Kawasaki-shi, Kanagawa

Claims (7)

[Claims] An apparatus for supporting a sliding body comprising a guide member supported at least at two points at or near both ends thereof, and a slider member guided by the guide member and slidable in a predetermined direction. Position detecting means for detecting a position of the slider member in the sliding direction on the guide member; force generating means for applying a pressing force or a tensile force to or near an end of the guide member; A correcting unit for correcting the positional displacement of the slider member, the correcting unit providing a control amount determined according to the position information detected by the position detecting unit to the force generating unit; Support device. 2. The sliding body supporting device according to claim 1, wherein the force generating means includes a force detecting means for detecting a magnitude of a force actually applied to the guide member, and wherein the correcting force control means comprises: A sliding body support device comprising feedback control means for automatically correcting a control amount applied to the force generating means according to the magnitude of the force detected by the force detecting means. 3. The sliding body support device according to claim 1, wherein the force generating means includes a first force generating means disposed at or near one end of the guide member, and another end of the guide member. A second force generation unit disposed in the vicinity thereof, wherein the correction force control unit generates the first force generation based on the position information detected by the position detection unit and a predetermined evaluation function. A supporting device for a sliding body, comprising: control amount determining means for independently determining both a control amount applied to the means and a control amount applied to the second force generating means. 4. The control device according to claim 1, wherein the correction force control means stores target value information of a control amount at each position obtained in advance by calculation in association with the position. A device for supporting a sliding body, characterized by comprising means. 5. The sliding body support device according to claim 1, wherein a position reference member is disposed along a slide path of the slider member in parallel with an axis of the guide member, and opposes the position reference member. And a distance detecting means for detecting a distance between the slider member and the opposing surface of the position reference member, wherein the correcting force control means detects the distance detected by the distance detecting means. And a control amount determining means for determining a control amount to be applied to the force generating means based on the position information detected by the position detecting means. 6. A sliding body support device according to claim 1, wherein a distance detecting means is disposed on said slider member in a state facing the surface on which the object to be measured is disposed, and a sliding path of said slider member. And a detachable position reference member disposed in parallel with the axis of the guide member and facing the detection surface of the distance detection means, wherein the correction force control means comprises: In the state where the member is mounted, the distance detected by the distance detecting means, and a target value of the control amount to be given to the force generating means based on the position information detected by the position detecting means is determined for each position, A supporting device for a sliding body, comprising: a control amount storage unit that stores a determined target value of a control amount in association with a position of a slider member. 7. The sliding body support device according to claim 1, wherein the force generating means is configured to apply a constant tensile force to an end of the guide member and to change the weight to an end of the guide member or in the vicinity thereof. And a variable force generating means for applying a force.