JP2008216122A - Surface property measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface property measuring device capable of avoiding reduction in straightness of a linear guide mechanism of a following probe and measuring accuracy caused by an installation error, without requiring highly accurate processing and assembling accuracy. <P>SOLUTION: This surface property measuring device has X, Y, Z axis driving mechanisms 3, 4 and 7, X, Y, Z axis displacement detectors 42, 43 and 44, the following probe 8, a straightness correction data storage part 33, and a correction arithmetic processing part 34. The following probe includes a sensor part 12, a driving actuator for displacing the sensor part in the Z axis direction, and a sensor part displacement detector 19 detecting a displacement quantity of the sensor part. The correction date storage part divides a moving range of the driving actuator into a plurality of sections, and stores a dislocation quantity in the respective axial directions in these respective divided sections as correction data. The correction arithmetic processing part determines to which divided sections a detecting value of the sensor part displacement detector belongs, and calculates a correction value by using the correction data on the corresponding divided section, and adds this value to the detecting value of respective axis displacement detectors. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface texture measuring device. More specifically, the present invention relates to a surface property measuring apparatus that measures surface properties such as the shape and surface roughness of an object to be measured using a scanning probe.

As surface texture measuring devices for measuring surface texture such as the shape and surface roughness of an object to be measured using a scanning probe, a roughness measuring machine, a contour measuring machine, a three-dimensional scanning measuring machine, and the like are known.
For example, in a three-dimensional scanning measuring machine, a scanning probe whose probe can be displaced in the Z-axis direction is attached to a Z-axis slider that can move in the vertical direction (Z-axis direction), and the measuring probe of this scanning probe is measured. The contact measurement is performed while moving the Z-axis slider in the vertical direction so that the pressing amount at this time (the pressing amount of the measuring element in the Z-axis direction) becomes constant.

Conventionally, a scanning probe attached to a scanning measuring machine, for example, a surface shape measuring tracer described in Patent Document 1, has a very small displacement in the Z-axis direction and a constant pushing amount. Therefore, the straightness of the linear guide mechanism that moves the probe in the Z-axis direction and the error in mounting the scanning probe, that is, the tilt error between the moving direction of the probe and the Z-axis has a large effect on the measurement accuracy. There are few.
Recently, in order to achieve high-speed measurement with low measurement force, the scanning probe itself has a wide measuring range, and the measurement force is actively controlled to perform high-speed scanning measurement with low measurement force. A system to do this has also been proposed.

JP-A 64-53109

In a conventional scanning measurement, when a scanning probe with a wide measurement range is used, the straightness of the linear guide mechanism that moves the probe in the Z-axis direction, the mounting error of the scanning probe, that is, the moving direction of the probe and the Z-axis The tilt error greatly affects the measurement accuracy.
For example, as shown in FIG. 8, depending on the straightness of the linear guide mechanism, the scanning probe mounting error, etc., when the probe 8A of the scanning probe 8 is displaced by Δz in the Z-axis direction, the X-axis and Y-axis directions are On the other hand, a deviation (Δx, Δy) occurs. Then, the detection value for detecting the displacement in the X-axis and the Y-axis is different from the measurement point of the measuring element 8A, so that a measurement error occurs.

  Therefore, in order to reduce the occurrence of this measurement error, it is required to assemble and process the straightness of the linear guide mechanism with high accuracy or to assemble the scanning probe with high accuracy. However, there is a limit to such high-precision processing and assembly, and the burden on the operator is large.

  The object of the present invention is to measure the surface properties that can avoid the deterioration of the measurement accuracy due to the straightness of the linear guide mechanism of the scanning probe, the mounting error of the scanning probe, etc. without requiring high-precision processing and assembly accuracy To provide an apparatus.

  The surface texture measuring apparatus according to the present invention includes an X-axis drive mechanism and a Y-axis drive mechanism that relatively displace a table on which an object is measured and a movable member in the X and Y axis directions orthogonal to each other in a horizontal plane, X-axis displacement detection means and Y-axis displacement detection means for detecting relative displacement amounts of the table and the movable member in the X and Y axis directions, and the Z axis perpendicular to the X and Y axis directions. A Z-axis drive mechanism for displacing in the direction, Z-axis displacement detection means for detecting the amount of displacement of the movable member in the Z-axis direction, a scanning probe provided on the movable member, a correction data table, and a control device, The scanning probe includes a housing attached to the movable member, a sensor unit provided on the housing and in contact with the surface of the object to be measured, and the sensor unit in the Z-axis direction. Z displaced to The correction data table is configured to include a fine movement mechanism and a sensor part displacement detection unit that detects a displacement amount of the sensor part with respect to the housing, and the correction data table includes a movement range of the scanning probe in the Z-axis direction of the Z-axis fine movement mechanism. Is divided into a plurality of sections, and the amount of deviation in each axial direction is stored as correction data in each of the divided sections, and the control device stores the detection value from the sensor unit displacement detection means in the correction data table. A correction value calculation unit that determines which division section belongs, calculates correction values in the respective axis directions by the Z-axis fine movement mechanism using correction data of the corresponding division sections, and obtained by the correction value calculation means. Coordinate value calculating means for calculating the coordinate value of the measuring element by adding the corrected value to the detection value of each axis displacement detecting means.

According to such a configuration, the scanning probe is driven by driving the X-axis drive mechanism and the Y-axis drive mechanism to relatively displace the table and the movable member in the X and Y-axis directions and driving the Z-axis drive mechanism. The probe of the scanning probe is brought into contact with the surface of the object to be measured while displacing in the Z-axis direction. The X-axis drive mechanism and the Y-axis drive mechanism are driven while driving the Z-axis fine movement mechanism so that the pushing amount of the probe of the scanning probe is constant, and the table and the movable member are moved in the X-axis direction and the Y-axis. Move relative to the direction.
In this relative movement, for example, at a certain time interval, the probe is in contact with the detection value from the X-axis displacement detection means, the Y-axis displacement detection means, the Z-axis displacement detection means, and the sensor part displacement detection means. When the measurement point coordinate value of the object to be measured is obtained, the shape, roughness, etc. of the surface of the object to be measured can be measured with a constant measuring force.

In the present invention, in the scanning measurement, the scanning measurement is performed while driving the Z-axis fine movement mechanism so that the measuring force of the probe of the scanning probe is constant. At that time, the movement range of the Z-axis fine movement mechanism of the scanning probe in the Z-axis direction is divided into a plurality of sections, and the deviation amount in each axis direction is stored in the correction data table as correction data in each of the divided sections. .
At the time of scanning measurement, it is determined which divided section stored in the correction data table the detection value from the sensor unit displacement detection means belongs to, and the Z-axis fine movement mechanism uses the correction data of the corresponding divided section. A correction value (amount of displacement) in each axial direction of the scanning probe is calculated. After that, the obtained correction value is added to the detection value of each axis displacement detection means (X, Y, Z axis displacement detection means), and the coordinate value of the measuring element, that is, the measurement object in contact with the measuring element. The measurement points are calculated.
Accordingly, it is possible to avoid a decrease in measurement accuracy due to straightness of the linear guide mechanism of the scanning probe, mounting error of the scanning probe, and the like, which are problems when performing scanning measurement while driving the Z-axis fine movement mechanism. This is because it is not necessary to assemble and process the straightness of the linear guide mechanism with high accuracy or to assemble the scanning probe with high accuracy in order to reduce the occurrence of measurement errors. And processing work, or the burden on the operator can be reduced.

In the surface texture measuring device of the present invention, the correction value calculation means of the control device determines which divided section the detection value from the sensor part displacement detection means belongs to and stored in the correction data table, and It is preferable to calculate the correction values in the respective axis directions by the Z-axis fine movement mechanism by linearly interpolating the correction data of the divided sections to be performed.
According to such a configuration, the correction data of each divided section is linearly interpolated to calculate the correction value in each axis direction by the Z-axis fine movement mechanism, so that the number of correction data is small, and each axis by the Z-axis fine movement mechanism is reduced. A direction correction value (displacement amount) can be calculated by a simple method.

In the surface texture measuring apparatus of the present invention, the scanning probe includes a base provided in the housing, a measuring element provided on the base and having a contact needle at a tip, and a vibration element that vibrates the measuring element, It is preferable to include a detection element that detects a vibration state of the probe and outputs a detection signal.
According to such a configuration, the measuring element is vibrated by the vibration element, and in this state, the measuring element is brought into contact with the surface of the object to be measured. When the probe contacts the surface of the object to be measured, the vibration of the probe is restrained, so that the detection signal from the detection element is attenuated. Therefore, high-precision scanning measurement can be realized by performing scanning measurement by controlling the Z-axis fine movement mechanism so that the attenuation amount of the detection signal from the detection element is always constant.

<Description of overall configuration (see FIGS. 1 and 2)>
FIG. 1 is a front view showing a surface texture measuring apparatus according to the present embodiment, and FIG. 2 is a side view of the surface texture measuring apparatus.
The surface texture measuring apparatus according to the present embodiment includes a base 1, an XY stage 2 as a table on which an object to be measured is placed, and an X and Y axis directions that displace the XY stage 2 in the X and Y axis directions orthogonal to each other in a horizontal plane. The shaft drive mechanism 3 and the Y-axis drive mechanism 4, the portal frame 5 provided over the upper surface of the base 1, and the Z-axis slider 6 as a movable member provided on the cross rail 5A of the portal frame 5 The Z-axis slider 6 includes a Z-axis driving mechanism 7 that displaces the Z-axis slider 6 in the Z-axis direction orthogonal to the X- and Y-axis directions, and a scanning probe 8 attached to the Z-axis slider 6.

The X-axis drive mechanism 3 and the Y-axis drive mechanism 4 are constituted by, for example, a feed screw mechanism having a ball screw shaft and a nut member screwed to the ball screw shaft.
Similarly to the X-axis drive mechanism 3 and the Y-axis drive mechanism 4, the Z-axis drive mechanism 7 is also configured by, for example, a feed screw mechanism having a ball screw shaft and a nut member screwed to the ball screw shaft. Yes.

<Description of scanning probe (see FIG. 3)>
The scanning probe 8 is for driving as a housing 11 attached to the Z-axis slider 6, a sensor unit 12 provided on the housing 11, and a Z-axis fine movement mechanism for displacing the sensor unit 12 in the Z-axis direction. Actuator 17 and sensor part displacement detector 18 (scale and detection) as sensor part displacement detection means for detecting the amount of displacement of sensor part 12 by drive actuator 17 (that is, the amount of displacement of sensor part 12 with respect to housing 11). Comprising a head).

  The sensor unit 12 includes a metal base 13, a stylus 14 that is provided on the base 13 and is in contact with the surface of the object to be measured, and a vibration element that vibrates (vibrates in the axial direction) the stylus 14. 15 and a detection element 16 that detects the vibration state of the stylus 14 and outputs it as a detection signal. At the tip of the stylus 14, a stylus 14A as a contact portion composed of a diamond tip or a ruby is bonded and fixed. The vibration element 15 and the detection element 16 are constituted by a single piezoelectric element, and are bonded and fixed to the base 13 one by one.

Now, when an input signal having a specific frequency and amplitude is given to the vibration element 15 of the sensor unit 12, the detection element 16 obtains an output signal having a specific frequency and amplitude.
When an input signal having a constant amplitude at the resonance frequency of the stylus 14 is applied to the vibration element 15 when the stylus 14 is not in contact with the object to be measured, the stylus 14 resonates and the detection element 16 outputs an amplitude Po. A signal is obtained. When the stylus 14 contacts the object to be measured, the amplitude of the output signal attenuates from Po to Px.
Therefore, when the sensor unit 12 is brought into contact with the object to be measured, the distance between the sensor unit 12 and the object to be measured is controlled by the driving actuator 17 so that the attenuation rate (Px / Po) is always constant. The shape and roughness of the object to be measured can be measured with a constant force.

<Description of control system (see FIG. 4)>
The present control system includes a control device 31, a scanning probe 8, a drive / displacement detection device 41, a display unit 51, and an input unit 61.
The drive / displacement detector 41 is an X-axis displacement detector that detects the amount of displacement of the XY stage 2 in the X- and Y-axis directions in addition to the X-axis drive mechanism 3, the Y-axis drive mechanism 4, and the Z-axis drive mechanism 7. 42, a Y-axis displacement detector 43, and a Z-axis displacement detector 44 for detecting the amount of displacement of the Z-axis slider 6 in the Z-axis direction.

  The control device 31 includes a scanning control unit 32 that drives the driving actuator 17 by using output signals from the sensor unit 12 and the sensor unit displacement detector 18 of the scanning probe 8, a straightness correction data storage unit 33, a count and The correction calculation processing unit 34, the control processing unit 35 that controls the shaft drive mechanisms 3, 4, and 7 based on the output from the counting and correction calculation processing unit 34, and the output from the counting and correction calculation processing unit 34 A measurement data processing unit 36 displayed on the display unit 51 is included.

The straightness correction data storage unit 33 divides the movement range in the Z-axis direction of the driving actuator 17 of the scanning probe 8 into a plurality of sections, and the deviation amount in each axis direction is stored as correction data in each of the divided sections. ing. That is, the straightness correction data table shown in FIG. 5 is stored.
The count and correction calculation processing unit 34 determines which divided section the detection value from the sensor unit displacement detector 18 belongs to and stored in the straightness correction data storage unit 33, and sets the correction data of the corresponding divided section. Correction value calculation means for calculating the correction value (displacement amount) of the sensor unit 12 in each axial direction by the driving actuator 17 and the correction value obtained by the correction value calculation means are used for each axis displacement detector, that is, Coordinate value calculation means for calculating the coordinate value of the stylus 14 by adding to the detection values of the X, Y, and Z axis displacement detectors 42, 43, and 44 is configured.

<Description of Straightness Correction Data (see FIGS. 5 and 6)>
FIG. 5 shows a straightness correction data table. The straightness correction data table is acquired by the following procedure and stored in the straightness correction data storage unit 33.
As shown in FIG. 6, the driving actuator 17 of the scanning probe 8 is driven to displace the sensor unit 12 in the Z-axis direction. In order to measure straightness at each measurement point (P0 to PN, where N is the number of measurement points) where the sensor unit 12 is displaced by the measurement interval d in the Z-axis direction, the reference is parallel to the Z-axis drive mechanism 7 installed in advance. A distance from a surface (not shown) is measured, and coordinate values (PNx, PNy) in the X-axis and Y-axis directions are obtained. After reading the coordinate values of each axis at all measurement points, each of the divided sections (Z> d, d ≦ Z <2d, 2d ≦ Z <3d... (N−1) · d is determined from these coordinate values. ≦ Z), a table of equations for each line segment (FIG. 5) is created.
In FIG.
Px, Py, Pz: coordinates of point P,
Lx, Ly, Lz: direction cosine,
Z: Indicates the distance from the origin.

<Description of scanning measurement (see FIG. 7)>
In the scanning measurement, the X-axis driving mechanism 3 and the Y-axis driving mechanism 4 are driven to displace the XY stage 2 in the X-axis direction and the Y-axis direction, and the Z-axis driving mechanism 7 is driven to scan the scanning probe 8. Is moved in the Z-axis direction, and the stylus 14 of the scanning probe 8 is brought into contact with the surface of the object to be measured.
The X-axis drive mechanism 3 and the Y-axis drive mechanism 4 are driven while the drive actuator 17 is driven so that the output signal from the detection element 16 of the scanning probe 8 has a constant attenuation rate, and the XY stage 2 is moved. Move in the X-axis direction and the Y-axis direction.

At the time of this measurement, the process of the flowchart shown in FIG.
In ST1 (step 1), the detection value Z from the sensor unit displacement detector 18 is read.
In ST2, it is checked which divided section of the straightness correction data tail (FIG. 5) the detected value Z from the sensor unit displacement detector 18 that has been read belongs.
In ST3, the correction value (displacement amount) of the sensor unit 12 by the driving actuator 17 is obtained using the correction data of the corresponding divided section. That is, the correction values (Δx, Δy, Δz) are obtained from the following equations.
Δx = Px + Lx × (Z−Pz)
Δy = Py + Ly × (Z−Pz)
Δz = Pz + Lz × (Z−Pz) = Z
In ST4, the correction values (Δx, Δy, Δz) are added to the detection values (NX, NY, NZ) of the X, Y, Z axis displacement detectors 42, 43, 44, and the coordinate value (NX ′) of the stylus 14 is added. , NY ′, NZ ′). That is,
NX ′ = NX + Δx
NY ′ = NY + Δy
NZ '= NZ + Δz
Ask from.
Accordingly, it is possible to avoid a decrease in measurement accuracy due to the straightness of the driving actuator 17 (linear guide mechanism) of the scanning probe 8 or an attachment error of the scanning probe 8, so that highly accurate scanning measurement can be realized.

<Effect of embodiment>
According to the present embodiment, the movement range of the scanning probe drive actuator 17 in the Z-axis direction is divided into a plurality of sections in advance, and the axial displacement of the sensor unit 12 by the drive actuator 17 in each divided section. The amount is stored in the correction data table as correction data, and at the time of scanning measurement, it is determined to which divided section the detection value from the sensor unit displacement detector 18 is stored in the correction data table. After calculating the correction values in the respective axial directions of the sensor unit 12 by the driving actuator 17 using the correction data of the divided sections to be detected, the correction values are detected by the X, Y, Z axis displacement detection means 42, 43, 44. Since the coordinate value of the stylus 14 is calculated by adding to the value, the straightness of the linear guide mechanism of the scanning probe, the mounting error of the scanning probe, etc. You can avoid a decrease in measurement accuracy due to.
This means that it is not necessary to assemble and process the straightness of the linear guide mechanism with high accuracy or to assemble the scanning probe with high accuracy in order to reduce the occurrence of measurement errors. And assembly work or the burden on the operator can be reduced.

<Modification>
The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the above-described embodiment, the XY stage 2 is configured to be movable in the X-axis direction and the Y-axis direction. However, the XY stage 2 and the Z-axis slider 6 that is a movable member are orthogonal to each other in the X and Y axis directions in the horizontal plane. You may comprise so that relative displacement is possible. For example, the stage 2 may be configured to be displaceable in the Y-axis direction, and the Z-axis slider 6 may be configured to be movable in the X-axis and Z-axis directions.

  In the above embodiment, the vibration type scanning probe 8 is used, but the present invention is not limited to this. For example, a structure for detecting the displacement of the stylus that occurs when the stylus 14 contacts the object to be measured, or a structure for detecting the bending of the stylus 14 that occurs when the stylus 14 contacts the object to be measured. May be.

  The present invention can be applied to a surface roughness measuring machine, a shape measuring machine, a three-dimensional scanning measuring machine, and the like that measure the surface roughness of an object to be measured. In particular, it is suitable for measuring fine shapes.

The front view which shows one Embodiment of the surface texture measuring apparatus which concerns on this invention. The side view of embodiment same as the above. The figure which shows the copying probe of embodiment same as the above. The figure which shows the measurement system of embodiment same as the above. The figure which shows the straightness correction data of embodiment same as the above. The figure which shows the acquisition procedure of straightness correction data in embodiment same as the above. 5 is a flowchart at the time of scanning measurement in the embodiment. The figure which shows the error of the Z-axis direction of a scanning probe.

Explanation of symbols

2 ... XY stage (table),
3 ... X axis drive mechanism,
4 ... Y-axis drive mechanism,
6 ... Z-axis slider (movable member),
7 ... Z-axis drive mechanism,
8 ... Copy probe,
11 ... Case,
12 ... sensor part,
13 ... Base,
14 ... Stylus (measuring element)
15 ... Excitation element,
16 ... detection element,
17 ... Actuator for driving (Z-axis fine movement mechanism),
18 ... sensor unit displacement detector (sensor unit displacement detection means),
31 ... Control device,
33 ... Straightness correction data storage unit (correction data table),
34... Counting and correction calculation processing unit (correction value calculation means, coordinate value calculation means)
42 ... X-axis displacement detector (X-axis displacement detector),
43 ... Y-axis displacement detector (Y-axis displacement detector),
44... Z-axis displacement detector (Z-axis displacement detector).

Claims (3)

An X-axis drive mechanism and a Y-axis drive mechanism for relatively displacing a table on which a measurement object is placed and a movable member in X and Y axis directions orthogonal to each other in a horizontal plane, and X and X of the table and the movable member X-axis displacement detection means and Y-axis displacement detection means for detecting a relative displacement amount in the Y-axis direction, and a Z-axis drive mechanism for displacing the movable member in the Z-axis direction orthogonal to the X and Y-axis directions A Z-axis displacement detection means for detecting a displacement amount of the movable member in the Z-axis direction, a scanning probe provided on the movable member, a correction data table, and a control device,
The scanning probe includes a housing attached to the movable member, a sensor unit provided on the housing and contacting a surface of the object to be measured, and the sensor unit is displaced in the Z-axis direction. Comprising a Z-axis fine movement mechanism, and a sensor part displacement detecting means for detecting a displacement amount of the sensor part relative to the housing;
The correction data table divides the movement range in the Z-axis direction of the Z-axis fine movement mechanism of the scanning probe into a plurality of sections, and stores a deviation amount in each axis direction as correction data in each of the divided sections.
The control device determines which divided section the detection value from the sensor unit displacement detection means belongs to and stored in the correction data table, and uses the correction data of the corresponding divided section to perform the Z-axis fine movement mechanism. The correction value calculation means for calculating the correction value in each axis direction by means of, and the correction value obtained by this correction value calculation means is added to the detection value of each axis displacement detection means to calculate the coordinate value of the measuring element And a coordinate value calculating means for performing surface texture measurement. In the surface texture measuring apparatus according to claim 1,
The correction value calculation means of the control device determines which divided section the detection value from the sensor unit displacement detection means belongs to, and linearly interpolates the correction data of the corresponding divided section Then, the surface property measuring apparatus is characterized in that the correction value in each axial direction by the Z-axis fine movement mechanism is calculated. In the surface texture measuring device according to claim 1 or 2,
The scanning probe detects a vibration state of a base provided on the casing, a measuring element provided on the base and having a contact needle at a tip, a vibration element that vibrates the measuring element, and the measuring element. A surface texture measuring apparatus comprising a detection element that outputs a detection signal.

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