JP2005300330A - Position measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring the position of a measuring object by scanning by a small-sized capacitance type sensor easily usable even in vacuum. <P>SOLUTION: When scanning is performed in the X-direction and in the Y-direction by the capacitance type sensor 2, an output change of the capacitance type sensor 2 shown in figure (b) is acquired. When scanning is performed in the X-direction by the capacitance type sensor 2, a point giving the maximum output is the center position in the X-direction of a target 3. Similarly, when scanning is performed in the Y-direction by the capacitance type sensor 2, a point giving the maximum output is the center position in the Y-direction of the target 3. Then, the position of the capacitance type sensor 2 is moved to the center position of the measured target 3, and the output of the capacitance type sensor 2 is measured on the position, to thereby determine the position in the Z-direction of the target 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention measures a capacitance between a target attached to a measured object and measures a one-dimensional, two-dimensional, or three-dimensional position of the measured object based on the measured capacitance. The present invention relates to a position measuring method.

  Capacitance type position measuring devices are well known, and are particularly used as distance measuring devices and level meters. The measurement principle is that the object to be measured or the target provided on it is one electrode, the electrode provided on the sensor side is the other electrode, and the capacitance between these electrodes is the distance between the object to be measured and the sensor. This is based on the fact that the capacitance changes between the two electrodes provided on the sensor side or changes depending on the distance between the object to be measured and the sensor.

  However, such a capacitance type position measuring apparatus is generally used for measuring a position in a one-dimensional direction. That is, assuming that the surface of the object to be measured is sufficiently large relative to the electrode surface on the sensor side, and the surface of the object to be measured is an infinite plane, the capacitance between such a plane or this The capacitance changing under the influence of such a plane was measured, and then the position of the object to be measured was measured.

  In general, it is not possible to detect the three-dimensional position of an object with a single sensor, and in order to measure the three-dimensional position of an object, each direction is measured using a distance measuring device, or one direction is measured. Is measured using a distance measuring device, and in a two-dimensional direction perpendicular to the distance measuring device, a two-dimensional position is imaged by an imaging device, and a position in the two-dimensional direction is obtained by image processing.

  If the three-dimensional position measurement is performed in this way, the number of measuring devices increases, and the sensor unit may not be accommodated in a narrow space. In particular, if the position of the object to be measured is to be detected three-dimensionally in a high vacuum, it may be difficult to arrange the sensor due to the structure of the sensor. Therefore, there is a need to newly arrange a partition wall, and there is a problem that the structure becomes complicated.

  The present invention has been made in view of such circumstances, and by scanning a capacitive sensor that is small and easy to use even in a vacuum, the one-dimensional, two-dimensional or It is an object to provide a method for measuring a position in a three-dimensional direction.

  A first means for solving the above problem is to measure the capacitance between the target attached to the object to be measured by relatively scanning the capacitance sensor and the target. A method for measuring a position of an object, wherein the target is formed in a predetermined three-dimensional shape, and an X-Y- based on a relationship between a relative position between the capacitance sensor and the target and the capacitance. A position detection method for measuring a position of the object to be measured in an XY two-dimensional direction or an XYZ three-dimensional direction in a Z three-dimensional space (claim 1).

  In this means, since the target has a predetermined three-dimensional shape, the capacitance value obtained by relatively scanning the capacitance sensor and the target two-dimensionally along the object to be measured and the three-dimensional object. Since the position of the target can be specified from the shape, the position in the XY direction of the object to be measured can be measured. In addition, if the relationship between the Z-direction position of the target and the output of the capacitive sensor is obtained in advance by calibration, the target, that is, the position of the measured object in the Z-direction can be measured from the output of the capacitive sensor. Is possible.

  The second means for solving the problem is a first means, wherein the target has at least a part of a spherical surface (Claim 2).

  In this means, the capacitance type sensor is scanned in the X direction, and the position where the output becomes maximum or minimum (the maximum or minimum depends on whether the target is convex or concave). If obtained, this becomes the center position in the X direction of the target. Similarly, when a capacitive sensor is scanned in the Y direction and the position where the output is maximized or minimized is obtained, it becomes the center position of the target in the Y direction.

  Therefore, the position of the target in the XY direction can be obtained by performing at least one scan in the X direction and the Y direction. Then, the position of the capacitive sensor is aligned with the center of the target and the output is measured, whereby the position of the target in the Z direction can be obtained. This makes it possible to measure the position of the object to be measured in the XY two-dimensional direction or the XYZ three-dimensional direction. Note that the scanning direction does not necessarily have to be the orthogonal XY directions, and the position of the moving object by scanning, that is, the position of the capacitance sensor and / or the position of the object to be measured (position of the moving object) is different. If it measures with this measuring apparatus, the XY direction position of a target can be calculated | required. In addition, since this means uses a spherical surface, it has a feature that the X-direction position and the Y-direction position of the target can be measured by X-direction scanning and Y-direction scanning at a short distance.

  The third means for solving the problem is the first means, and when the relative scanning direction is the X direction and the Y direction, the target has axes in the X direction and the Y direction. A position detection method comprising a part of an elliptical spherical surface.

  In this means, as in the case of the second means, the center position of the elliptic sphere in the X direction and the Y direction can be obtained by at least one scan in each of the X direction and the Y direction. Has the same effect as.

  A fourth means for solving the problem is the first means, wherein the target has a part of a cylinder having an axis parallel to the Z-axis. 4).

  In this means, when an electrostatic capacitance type sensor is scanned in the X direction, an output line symmetric with respect to a certain X value is obtained. This object center is the X coordinate of the center of the target. Similarly, when a capacitive sensor is scanned in the Y direction, an output line-symmetric with respect to a certain Y value is obtained. This target center is the Y coordinate of the center of the target. Therefore, the X direction center and the Y direction center of the target can be obtained by at least one scan in each of the X direction and the Y direction. Then, the position of the target in the Z direction can be obtained by positioning the capacitance type sensor at the center and measuring the output. Similarly to the second means, the scanning direction of this means does not necessarily have to be the XY orthogonal direction, and may be different directions.

  This makes it possible to measure the position of the object to be measured in the XY two-dimensional direction or the XYZ three-dimensional direction. In this means, unlike the second means and the third means, the surface of the target at the center position in the X and Y directions is a flat surface. Accuracy can be improved.

  The fifth means for solving the above-mentioned problem is the first means, and when the relative scanning direction is the X direction and the Y direction, the target is an elliptical axis in the X direction and the Y direction. It is a position detection method (Claim 5) characterized by having a part of elliptical cylinder which has.

  In this means, as in the fourth means, the center position of the elliptic cylinder in the X direction and the Y direction can be obtained by at least one scan in each of the X direction and the Y direction. Has the same effect as.

  According to a sixth means for solving the above-mentioned problem, the capacitance between the target attached to the object to be measured is measured by relatively scanning the capacitance sensor and the target, and the capacitance is measured. Based on the relationship between the relative position of the mold sensor and the target and the measured capacitance, in the XYZ three-dimensional space, when the scanning direction of the capacitance sensor is the X direction, A method for measuring a position in the X direction of the object to be measured, wherein when the Y direction is determined so that the surface of the object to be measured is parallel to the XY plane, the surface of the target in a predetermined range of Y The position detection method (claim 6) is characterized in that the shape in the cross section in the X direction is represented by Z = f (X).

  In this means, the output obtained by X-direction scanning does not change even if the Y-direction position of the capacitive sensor changes. Therefore, the X direction scanning may be performed once. Then, if the relationship between the capacitance type sensor output obtained when the X direction scanning is performed and the position of the capacitance type sensor is obtained in advance, the center position of the target in the X direction is determined based on this relationship. Can be sought. Therefore, the X direction position of the object to be measured can be obtained.

  When the same condition holds for the Y-direction cross section of the target, the Y-direction position of the object to be measured can be obtained in the same manner by reading the above description with X and Y interchanged. Therefore, this means can be used as one element of two-dimensional position measurement and three-dimensional position measurement.

  The seventh means for solving the above-mentioned problem is to measure the capacitance between the target attached to the object to be measured by relatively scanning the capacitance sensor and the target, and the capacitance. Based on the relationship between the relative position of the mold sensor and the target and the measured capacitance, in the XYZ three-dimensional space, the scanning direction of the capacitance sensor is the X direction and the Y direction. When measuring the position of the object to be measured in the XYZ three-dimensional direction, the shape of the surface of the target at the predetermined range Y in the X-direction cross section is Z = f (X), the predetermined range The shape of the surface of the target at X in the Y-direction cross section is expressed by Z = g (Y), and the range where the Z-direction position is maximum or minimum is sufficiently wide in a plane parallel to the XY plane. Near the center of the range A position measurement method (claim 7), characterized in that the output also by scanning the capacitive sensor is not to change Te.

  In this means, the method for obtaining the X direction position and the Y direction position of the target is the same as the fifth means. If the X-direction position and the Y-direction position of the target are obtained, the capacitive sensor can be positioned at a position where the Z-direction position of the target is maximum or minimum.

  If the output of the capacitive sensor is measured in this state, the position of the target in the Z direction can be obtained. At this time, the range in which the position in the Z direction is maximum or minimum is sufficiently wide in a plane parallel to the XY plane so that the output does not change even when the capacitive sensor is scanned in the vicinity of the center. Therefore, the Z-direction position can be measured accurately.

  The eighth means for solving the problem is the sixth or seventh means, wherein the shape of the target is a truncated pyramid or a prism (claim 8).

  The truncated pyramid or the prism is a simple shape, and is a desirable shape as the shape of the target used for the sixth or seventh means.

  A ninth means for solving the problem is the sixth means or the seventh means, wherein one of the functions Z = f (Y) and Z = g (X) has a plurality of irregularities. It is characterized by having (claim 9).

  In this means, since one of the functions Z = f (Y) and Z = g (X) has a plurality of irregularities, the X direction of the target is based on the output of the capacitive sensor based on the plurality of irregularities. The position or the Y direction position can be determined. Therefore, the X direction position measurement accuracy or the Y direction position measurement accuracy can be improved.

  A tenth means for solving the problem is the sixth to ninth means, wherein the method for obtaining the position of the object to be measured in the X direction or the Y direction is a direction in which the position of the target is measured. A cross-correlation between the function indicating the cross-section of and the output when the scanning in the measuring direction is taken, and the position of the object to be measured is determined based on the point where the cross-correlation value is maximum. This is a characteristic position measuring method (claim 10).

  In this means, since the position in the X direction or the Y direction is determined by the cross correlation method, the shape of the target and the output shape of the capacitive sensor do not accurately correspond (for example, the output of the capacitive sensor). Can be accurately determined in the X-direction or Y-direction position of the target, and thus the X-direction or Y-direction position of the object to be measured can be accurately determined.

  An eleventh means for solving the problem is to measure the capacitance between the target attached to the object to be measured by scanning the capacitance type sensor, and position of the capacitance type sensor. And X-Y2 of the object to be measured when the scanning direction of the capacitive sensor is set to the X direction and the Y direction in an XYZ three-dimensional space based on the relationship between the measured capacitance and the measured capacitance. A method of measuring a position in a dimensional direction, wherein the shape of the target surface in the X-direction cross section is line symmetric about the same Y value for any X, and the shape in the Y-direction cross section is The position measuring method (claim 11) is characterized in that every Y is line-symmetric with respect to the same X value.

  In this means, the capacitive sensor is scanned once for each of the X-axis direction and the Y-axis direction. In the case of scanning in the X-axis direction, the output becomes a line object around a certain value of X, and in the case of Y-axis direction scanning, the output becomes a line object around a certain value of Y. Therefore, by obtaining the values that are the centers of the objects, the X-direction position and the Y-direction position of the center of the target are determined, and the X-direction position and the Y-direction position of the object to be measured can be obtained from this.

  A twelfth means for solving the problem is to measure a capacitance between the target attached to the object to be measured by scanning a capacitance type sensor, and position of the capacitance type sensor. And X-Y of the object to be measured when the scanning direction of the capacitance type sensor is the X direction and the Y direction in the XYZ three-dimensional space based on the relationship between the measured capacitance and the measured capacitance. A method for measuring a position in a three-dimensional direction, wherein the shape of the surface of the target in the X-direction cross section is axisymmetric about the same Y value for any X, and the shape in the Y-direction cross section Are symmetrical about the same X value for any Y, and the range in which the position in the Z direction is maximum or minimum is sufficiently wide in a plane parallel to the XY plane, and the center of the range The capacitive sensor in the vicinity It is a position measuring method according to claim (claim 12) which output also be 査 is not to change.

  In this means, the method for obtaining the X-direction position and the Y-direction position of the target is the same as the eleventh method. If the X-direction position and the Y-direction position of the target are known, the Z-direction position of the target can be measured by positioning the capacitive sensor at the position where the Z-direction position is maximum or minimum. At this time, since the range in which the position in the Z direction is maximum or minimum is sufficiently wide in a plane parallel to the XY plane, the position in the Z axis direction can be accurately measured. Thereby, the X, Y, and Z three-dimensional direction positions of the object to be measured can be accurately obtained.

  As described above, according to the present invention, a capacitive sensor that is small and easy to use even in a vacuum and a target are relatively scanned, so that one-dimensional, two-dimensional or A method of performing position measurement in a three-dimensional direction can be provided.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of a method for detecting the position of the DUT 1 by scanning the capacitive sensor 2. The device under test 1 is provided with a target 3, and the position of the device under test 1 is measured by measuring the position of the target 3 with a capacitive sensor 2.

  In space, as shown in FIG. 1 (a), an XYZ orthogonal coordinate system is taken, the device under test 1 is parallel to the XY plane, and the capacitive sensor 2 is It is assumed that it is attached in the Z-axis positive direction (upper side in FIG. 1A). The shape of the target 3 is a shape obtained by cutting a sphere on the surface of the DUT 1. The target 3 is made of a conductor and is grounded. The plane where the target 3 and the DUT 1 intersect is a circle, and the reference position of the DUT 1 is the case where the center O of this circle is at a point where X = 0 and Y = 0.

  In the state in which the capacitive sensor 2 is located above the target 3, the center position of the capacitive sensor 2 in the XY direction and the position of the center O of the circle are usually as shown in FIG. Is not. In this state, when the capacitive sensor 2 is scanned in the X and Y directions, a change in the output of the capacitive sensor 2 as shown in FIG. 1B is obtained.

Since the target 3 has a shape obtained by cutting the sphere along the surface of the DUT 1 (parallel to the XY plane), the maximum output is obtained when the capacitive sensor 2 is scanned in the X direction. The point is the center position in the X direction of the target 3 regardless of the position in the Y direction of the capacitive sensor 2. The value of X at this time is X _0. Similarly, the point that gives the maximum output when the capacitive sensor 2 is scanned in the Y direction is the center position in the Y direction of the target 3 regardless of the X direction position of the capacitive sensor 2. The value of Y at this time is Y _0.

Next, the position of the capacitive sensor 2 is moved to (X ₀ , Y ₀ ). Then, the center of the capacitive sensor 2 coincides with the center O of the circle as shown in FIG. That is, the highest position of the target 3 that is a spherical surface is measured. If the relationship between the position of the target 3 in the Z direction at this position and the output of the capacitive sensor 2 is obtained in advance by calibration, the output of the capacitive sensor 2 is measured to measure the Z of the target 3. You can see the direction position. When this position is Z ₀ , (X ₀ , Y ₀ , Z ₀ ) can be the position of the target 3, and from this, the position of the DUT 1 in the three-dimensional direction can be known.

  In the above description, the shape of the target 3 is a shape obtained by cutting a sphere by the surface of the DUT 1, but the shape of the target 3 is parallel to the X axis and the Y axis, respectively. Even if the ellipsoidal sphere is cut out on the surface of the DUT 1, it will not be necessary to explain that the above-described effects can be obtained. Although the capacitance sensor is moved in the present embodiment, it can be measured if the relative position changes, the target side can also be moved, and the target and the capacitance can be moved. Both of the sensors may be moved. Although not shown, the movement position of the target or the capacitance sensor is measured by another length measuring device or the like, or the driving force for movement, for example, the current value or the voltage value is obtained. deep.

  In the following description, the relative relationship between the DUT 1, the capacitive sensor 2, and the target 3, and the scanning method of the capacitive sensor 2 are the same as those shown in FIG. Only the different parts will be described.

  FIG. 2 is a diagram illustrating examples of various targets. FIG. 2A shows a target having a quadrangular pyramid shape, and the directions of the rectangular sides of the upper surface and the lower surface are the X direction and the Y direction. Such a target is the same when the cross-sectional shape in the X direction is cut at any position of Y belonging to the upper surface range. Similarly, the cross-sectional shape of the Y direction is cut at any position of X belonging to the upper surface range. Even so it is the same.

Therefore, the same waveform output can be obtained regardless of the position of Y in the X direction, and the same waveform output can be obtained in any position of the X in the Y direction. Is obtained. Now, let us consider scanning in the X direction, the shape of the X direction cut surface of the target is represented by Z = f ₁ (X), and the relationship between the X direction position of the capacitive sensor and its output A is It is assumed that A = A (x). At that time, the cross-correlation between f ₁ (X) and A (x) is taken. That is,

Ask for. The value of τ that maximizes S (τ) is taken as the X-direction position of the target. Similar measurement and calculation are performed in the Y direction, and the value of τ that maximizes the cross-correlation function is set as the Y direction position of the target. If the X-direction position and the Y-direction position of the target are determined, the position of the capacitive sensor can be adjusted to the center of the target by moving the capacitive sensor to the center position.

  Since the target is a quadrangular pyramid, the rectangular area on the upper surface is wide, and this surface is parallel to the XY plane. Therefore, as described above, even when the position of the sensor of the capacitive sensor is slightly shifted in the X direction and Y direction as compared with the case where a part of a sphere or a part of an elliptic sphere is used as a target, Since the output of the capacitive sensor does not change, the accuracy of measuring the position of the target in the Z direction can be improved.

  In addition, in this way, the cross-sectional shape in the X direction is the same when cut at any position of Y in the predetermined range, and the cross-sectional shape in the Y direction is the same regardless of the position of X in the predetermined range. If a target such as is used, the amount of rotation of the object to be measured around the Z axis can also be obtained.

That is, by changing the capacitance type sensor in the X direction at a position separated by a predetermined distance ΔY in the Y direction, the center position of the target in the X direction at each Y position is obtained, and the difference between the center positions is obtained. Is ΔX, the rotation amount θ around the Z-axis of the object to be measured is
θ = tan ⁻¹ (ΔY / ΔX)
Can be obtained as The θ can be obtained in the same manner by using the Y-direction scanning of the capacitive sensor.

  Furthermore, if a target with a sufficiently wide upper surface such as a quadrangular pyramid is used, the Z-direction position of each of three or more (X, Y) combinations that are not on the same straight line is obtained. It is also possible to determine the inclination of the object.

  Even if a target made of a quadrangular prism is used instead of the quadrangular pyramid, it will not be necessary to explain that the same effect can be obtained by the same measurement method.

  FIG. 2B is a target having a truncated cone shape, and the upper surface and the lower surface are parallel to the XY plane. Such a target is symmetrical with respect to the Y line having the same value, regardless of the Y value at any position corresponding to the Y value. Similarly, when a cross section in the Y direction is viewed at a position corresponding to any X value, the cross section is symmetric with the Y line having the same value as the symmetry axis.

Therefore, by scanning the capacitance sensor in the X direction at an arbitrary position, knowing the value of X as the axis of symmetry of its output, it can be seen it is a X-direction central position X ₁ of the target. Similarly, scanning the capacitance sensor at any position in the Y direction, knowing the value of Y to be the axis of symmetry of its output, it can be seen it is a Y-direction center position Y ₁ of the target. Therefore, the position in the X direction and the Y direction of the object to be measured can be known from these positions.

Subsequently, the center position of the capacitive sensor is set to (X ₁ , Y ₁ ), and by measuring the output of the capacitive sensor in that state, the position of the target in the Z direction can be known. The position of the object to be measured in the X direction and the Y direction can be known. The fact that the measurement accuracy is not affected even if the position of the capacitive sensor is slightly deviated from (X ₁ , Y ₁ ) is the same as in the case of the quadrangular frustum shown in FIG. It is the same as in the case of the quadrangular pyramid shown in FIG. 2A that the inclination of the object to be measured can be obtained by measuring the direction position at three or more points that are not in the same straight line. Further, it will not be necessary to explain that the same effect can be obtained by using a cylinder instead of the truncated cone.

  The method for obtaining the target center from the obtained waveform of the capacitive sensor can be arbitrarily selected from known ones, but the simplest one is a method using an inverted cross-correlation method. is there. For example, when the output of the capacitive sensor obtained by scanning in the X direction is B (x), a cross-correlation function S ′ (τ ′) expressed by the following equation is obtained.

The value ½ of τ ′ that maximizes the cross-correlation function S ′ (τ ′) is set as the target center.

  FIG. 2 (c) shows a target having a triangular cross-section with two triangular wave irregularities on the left and right sides and a flat portion in the center when viewed in the X-direction cross section. is there. Such target position measurement in the Y direction can be performed by the method described in the description of FIG.

  X-direction position measurement can be performed by the method described in the description of FIG. In that case, in the target shown in FIG. 2C, since a plurality of irregularities are formed, the position in the X direction can be determined based on the plurality of irregularities (for example, by the cross-correlation method described above) The accuracy can be increased accordingly. As is apparent, a plurality of irregularities arranged in the X direction shown in FIG. 2C can also be formed in the Y direction, and the positional accuracy in the Y direction can be improved.

  Since the position measurement in the Z direction can be performed using a wide portion at the center, accurate measurement is possible even if the X-direction position and the Y-direction position of the capacitive sensor are slightly shifted. Needless to say, the irregularities provided on the left and right of the central flat portion may be of any shape. In the case of left-right symmetry, the X direction position measurement method performed in the description of FIG. 2B can be used.

It is a figure which shows one example of the method of detecting the position of a to-be-measured object by scanning a capacitive sensor. It is a figure which shows the example of various targets.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Object to be measured 2 ... Capacitance type sensor 3 ... Target

Claims (12)

A method of measuring the position of the object to be measured by measuring the capacitance between the target attached to the object to be measured by relatively scanning the capacitance sensor and the target,
The target has a predetermined three-dimensional shape, and the X of the object to be measured is measured in an XYZ three-dimensional space based on the relative position between the capacitance sensor and the target and the capacitance. A position detection method characterized by measuring a position in a Y2-dimensional direction or an XYZ three-dimensional direction. The position detection method according to claim 1, wherein the target has at least a part of a spherical surface. 2. The position detection method according to claim 1, wherein when the relative scanning direction is the X direction and the Y direction, the target has a part of an elliptical sphere having axes in the X direction and the Y direction. A position detection method characterized by the above. The position detection method according to claim 1, wherein the target has a part of a cylinder having an axis parallel to the Z axis. The position detection method according to claim 1, wherein when the relative scanning direction is the X direction and the Y direction, the target has a part of an elliptic cylinder having an elliptical axis in the X direction and the Y direction. A position detection method characterized by the above. The capacitance between the target attached to the object to be measured is measured by relatively scanning the capacitance sensor and the target, the relative position between the capacitance type sensor and the target, and the target A method for measuring the position of the object to be measured in the X direction in the XYZ three-dimensional space based on the measured capacitance relationship, where the scanning direction of the capacitive sensor is the X direction. When the Y direction is determined so that the surface of the object to be measured is parallel to the XY plane, the shape in the X direction cross section of the surface of the target in a predetermined range of Y is Z = f (X). A position detection method characterized by being represented. The capacitance between the target attached to the object to be measured is measured by relatively scanning the capacitance sensor and the target, the relative position between the capacitance type sensor and the target, and the target Based on the relationship of the measured capacitance, when the scanning direction of the capacitance type sensor is set to the X direction and the Y direction in the XYZ three-dimensional space, XYZ3 of the object to be measured. A method for measuring a position in a dimensional direction, wherein the shape of the surface of the target in the X range in the predetermined range of Y is Z = f (X), and the shape of the surface of the target in the Y range of the predetermined range in the Y direction Is represented by Z = g (Y), and the range in which the position in the Z direction is maximum or minimum is sufficiently wide in a plane parallel to the XY plane, and the capacitance type sensor is located near the center of the range. Even if you scan Position measuring method characterized in that the force is not to change. The position measurement method according to claim 6 or 7, wherein the shape of the target is a truncated pyramid or a prism. The position measurement method according to claim 6 or 7, wherein one of the functions Z = f (Y) and Z = g (X) has a plurality of irregularities. 10. The position measurement method according to claim 6, wherein a method for obtaining a position of the object to be measured in the X direction or the Y direction is a cross section in a direction in which the position of the target is measured. And the position of the object to be measured is determined based on the point where the cross-correlation value is maximized. Position measurement method. The capacitance between the target attached to the object to be measured is measured by scanning the capacitance type sensor, and based on the relationship between the position of the capacitance type sensor and the measured capacitance. In the XYZ three-dimensional space, when the scanning direction of the capacitive sensor is the X direction and the Y direction, the method measures the position in the XY two-dimensional direction of the object to be measured, The shape of the target surface in the X-direction cross section is line symmetric with the same Y value as the center for any X, and the shape in the Y-direction cross section is the line with the same X value as the center for any Y A position detection method characterized by being symmetrical. The capacitance between the target attached to the object to be measured is measured by scanning the capacitance type sensor, and based on the relationship between the position of the capacitance type sensor and the measured capacitance. In the XYZ three-dimensional space, when the scanning direction of the capacitive sensor is the X direction and the Y direction, the position of the object to be measured is measured in the XYZ three-dimensional direction. The shape of the target surface in the X-direction cross section is line symmetric about the same Y value for any X, and the shape in the Y-direction cross section is centered on the same X value for any Y. Further, a range in which the position in the Z direction is maximum or minimum is sufficiently wide in a plane parallel to the XY plane, and the capacitive sensor is scanned in the vicinity of the center of the range. The output is kept unchanged Position measuring method according to claim Rukoto.

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