JP3508368B2 - Image measuring machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an image measuring device for measuring a contour shape of a test object. 2. Description of the Related Art Conventionally, as this type of image measuring device, for example, an image of a test object mounted on a stage is captured from above through an optical system, and the light intensity distribution of the captured image is measured. A CCD camera that outputs an electric signal corresponding to the image signal, and an edge of a contour shape of the test object within an index set in an imaging range captured by the CCD camera is detected by image processing based on the electric signal, and edge coordinates are detected. 2. Description of the Related Art There is known an image processing device that includes an image processing device that outputs a signal representing a value and that measures a contour shape of a test object. In this image measuring apparatus, when measuring the contour shape of a test object, the next measurement target point is set based on the edge coordinate values of a plurality of measurement points whose edges have been detected immediately before. The position and angle direction of the index are set with respect to the measurement target point, and the detection of the edge of the contour shape within the index is repeatedly performed on a plurality of points along the contour shape. However, in the above prior art, the angle direction of the index at the next measurement target point is determined based only on the edge coordinate values of a plurality of measurement points whose edges have been detected immediately before. Is set perpendicular to the contour shape expected at the measurement target point.When the curvature change of the contour shape is large, the angle direction of the set index is perpendicular to the contour shape at the measurement target point. It is not always the direction. As a result, the edge is detected in a state where the index is inclined from the direction perpendicular to the contour shape at the measurement target point, and the detection position of the edge varies, and the accuracy of the edge detection image processing deteriorates. There was a problem that it would. The present invention has been made in view of such circumstances, and an object of the present invention is to provide an image measuring machine with improved contour shape measurement accuracy. According to a first aspect of the present invention, there is provided an image measuring apparatus for solving the above-mentioned problems, wherein an image of a test object mounted on a stage is converted via an optical system. Capturing, capturing means for outputting an electric signal according to the light intensity distribution of the captured image, and the edge of the contour shape of the test object in an edge detection area set in the capturing range captured by the capturing means. Image processing means for detecting a signal representing an edge coordinate value by image processing based on an electric signal, and an image measuring device for measuring the contour shape, wherein each of a plurality of points along the contour shape is A first method of setting the position and direction of the edge detection area and capturing the edge coordinate values from the image processing unit at each measurement point at which the edge is detected.
A measurement unit and a data creation unit that creates teaching data representing the position and direction of the edge detection area at each measurement point based on the edge coordinate values of each measurement point captured by the first measurement unit. A second measuring unit for measuring the contour shape according to the teaching data, wherein the data creating unit determines a direction of the edge detection area at each of the measuring points by a method of the contour shape at each of the measuring points. It is characterized in that teaching data in a line direction is created. [0007] The data creation section is data representing the position and direction of the edge detection area at each measurement point based on the edge coordinate values of each measurement point taken in by the first measurement section. Teaching data in which the direction of the edge detection area is the normal direction of the contour shape obtained from a plurality of points including the point and points before and after the point is created, and the second measuring unit measures the contour shape according to the teaching data. Therefore, even when the change in the curvature of the contour shape is large, the edge is always detected in a state where the angle direction of the index is perpendicular to the contour shape at each measurement point, and the detected position of the edge does not vary. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an image measuring device according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing the image measuring device. As shown in FIGS. 1 and 2, the image measuring device comprises a measuring device main body 1 and a control unit 2. A support 3 is provided on the measuring instrument body 1, and a monitor 4 is provided on the control unit 2. The main body 1 of the measuring machine comprises a base 3a of a support 3
The XY stage 5 includes an XY stage 5 provided thereon, and an imaging unit 6 supported by a column 3 b of the support 3 so as to be located above the stage 5. The XY stage 5 is movable in two orthogonal directions (X-axis and Y-axis directions) in a horizontal plane. On the upper surface of the stage 5, a test object (for example, a test object as shown in FIG. 3) 7 having a two-dimensional contour shape and a small thickness is placed. The test object 7 is illuminated by the transmitted illumination optical system 8 provided on the base unit 3a or the incident illumination optical system 9 provided on the imaging unit 6 (see FIG. 2). On the XY stage 5, as shown in FIG.
An XY stage drive unit 10 for electrically moving the XY stage 5 in two directions based on an input stage movement command;
A stage position detector 11 is provided for detecting the coordinates of the XY stage 5 and outputting a signal representing the stage coordinate value. The XY stage drive unit 10 has an X-axis motor and a Y-axis motor (not shown) for driving the XY stage 5 in the X-axis and Y-axis directions, respectively. The stage position detector 11 has an X-axis encoder and a Y-axis encoder (not shown) for detecting the positions of the XY stage 5 in the X-axis and Y-axis directions, respectively. The imaging unit 6 includes, in addition to the epi-illumination optical system 9,
An imaging optical system 12 for imaging light from the test object 7, an image of the test object 7 formed by the optical system 12 (capture), and electricity corresponding to the light intensity distribution of the captured image. A CCD camera 13 for outputting a signal is provided. Imaging optical system 1
The magnification of 2 may be fixed or variable. The control unit 2, as shown in FIG.
An image processing unit 21 to which an electric signal output from the CD camera 13 is input, a contour shape measuring unit 22, and an index setting unit 2
3, measurement condition table 24, and measurement data table 2
5 and a data output unit 26. The control unit 2 is configured by a computer having an input device such as a keyboard (not shown), an input circuit, an output circuit, a central processing circuit, and the like. The image processing section 21 performs image processing on the electric signal output from each pixel of the CCD camera 13 and converts the captured image of the test object 7 into an image on a monitor screen 4a of the monitor 4 (see FIG. 4). The image signal for display is output to the monitor 4. Further, the image processing unit 21
An index (edge detection area) 1 indicating an edge detection area upon receiving index position data output from the index setting unit 23.
5 is displayed on the monitor screen 4a at a position and angle corresponding to the data of the index position.
It is configured to output to Further, the image processing section 21 performs image processing on the electric signal output from the CCD camera 13, detects the edge of the contour 7a of the test object 7 within the index 15, and detects the detected edge point 16 (see FIG. 4). ) In the monitor screen 4a are sequentially detected for each measurement point 17 (see FIG. 3) along the contour shape 7a, and the data of each edge coordinate value is detected by the contour shape measuring unit 22.
It is configured to output to The contour shape measuring section 22 performs a measurement for taking in the edge coordinate values of each measurement point 17 at a certain interval (for example, at a constant interval) along the contour shape 7a of the test object 7. The contour shape measurement unit 22 includes a pre-measurement unit (first measurement unit) 51 that performs provisional measurement, a measurement instruction data creation unit (tching data creation unit) 52, and a replay measurement unit 53 that performs actual measurement.
It is composed of The pre-measurement unit 51 is used to calculate the contour shape 7 of the test object 7.
It is configured to execute pre-measurement (see FIG. 5) in which edge coordinate values of each measurement point 17 are taken at regular intervals along a. The pre-measurement unit 51 performs pre-measurement,
A next measurement target point 18 (see FIG. 7) to which the index 15 is moved is set, and the index 15 corresponding to the measurement target point 18 is set.
Is output to the index setting unit 23, and a stage movement instruction is output to the XY stage drive unit 10, indicating an angle direction orthogonal to the position and the measurement target direction 30 (see FIG. 7). ing. Further, the pre-measurement section 51 includes the image processing section 21.
The coordinate values (measurement point coordinate values) of the respective measurement points are calculated based on the edge coordinate values of the respective measurement points output from the stage and the stage coordinate values of the respective measurements output from the stage position detector 11, and the calculation is performed. An operation unit for sequentially outputting the results to the measurement instruction data creation unit 52 is provided. This operation unit performs an operation represented by the following equation. (Measurement point coordinate value) = (Stage coordinate value) +
(Edge coordinate value × monitor screen correction value) Here, the monitor screen correction value is a ratio between the dimension on the XY stage 5 and the dimension on the monitor screen 4a. A measurement instruction data creation section (hereinafter simply referred to as a data creation section) 52 stores the measurement point coordinate values of each measurement point output from the pre-measurement section 51 in a data table. The data creation section 52 calculates the coordinates of the measurement points of each measurement point output from the pre-measurement section 51 (the pre-measurement section 5
Based on the edge coordinate value of each measurement point captured in step 1), measurement instruction data (teaching data) representing the position and direction of the index 15 at each measurement point is created, and the replay measurement unit 5
3 and stored in a storage device. The data creation unit 52 sets the direction of the index 15 at each measurement point as the normal direction of the contour shape obtained from a plurality of points including that point at each measurement point and points before and after that point. As a method of determining the normal direction of the contour shape at each measurement point, shape interpolation such as linear interpolation, circular interpolation, and spline interpolation is performed from the coordinates of each measurement point of a plurality of measurement points at which edges have been detected. There is a way to ask. For example, the calculation of the normal direction by circular interpolation at the measurement point Pi is performed as follows. (1) The center O of the arc passing through the three measurement points Pi-1, Pi and Pi + 1 is calculated. (2) The direction connecting the measurement point Pi and the center O of the arc is defined as the normal direction. The replay measuring section 53 is configured to execute a replay measuring process shown in FIG. That is, in accordance with the measurement instruction data output from the data creation unit 52, an index setting command indicating the position and the angle direction of the index 15 is output to the index setting unit 23 for each measurement point, and the image processing unit 21 outputs Is calculated based on the edge coordinate value of each measurement point and the stage coordinate value in each measurement, and the calculation results are sequentially output to the measurement data table 25. Is configured. The calculation of the measurement point coordinate value is the same as the calculation in the calculation unit of the pre-measurement unit 51. The index setting unit 23 sets index 15 for setting the index 15 at the position and angle direction on the monitor screen 4a designated by the index setting command output from the pre-measurement unit 51 or the replay measurement unit 53. Is output to the image processing unit 21. The measurement condition table 24 includes coordinates of a measurement start position (first measurement point) and a measurement end position (last measurement point) of the contour 7a of the test object 7, a measurement target direction at the measurement start position, The interval between the measurement points 17 (for example, at regular intervals,
The measurement conditions including the data respectively representing the measurement pitches P) shown in FIG. The measurement data table 25 stores data of coordinate values (measurement point coordinate values) of each measurement point output from the replay measurement unit 53. The data output section 26 is for displaying or printing and outputting the measurement data (coordinate values of all the measurement points) stored in the measurement data table 25 after the measurement is completed. Next, the operation of the embodiment having the above configuration will be described with reference to the flowcharts of FIGS. 5 and 6 and FIGS. First, a pre-measurement process executed by the pre-measurement section 51 will be described. When the contour shape measurement process shown in FIG. 5 is started, in step 101, the coordinate values of the preset measurement start position and measurement end position are respectively set in the measurement condition table 24.
Take in from. In the next step 102, step 101
Set the measurement start position captured in step 1 as the first measurement target point. In the next step 103, the monitor screen 4a
The index 15 is moved so that the index 15 comes to the upper measurement target point (here, the first measurement target point set in step 102). At this time, the index 15 is displayed at the first measurement target point on the monitor screen 4a. In the next step 104, the edge point coordinates of the contour 7a in the index 15 (here, the edge point coordinates of the first measurement target point) are fetched. That is, the edge coordinate value of the first measurement target point output from the image processing unit 21 is captured. In the next step 105, the stage coordinate values output from the stage position detecting section 11 and the step 1
Based on the edge coordinate values acquired in step 04, the coordinate value of the measurement point within the index 15 (measurement point coordinate value: here, the coordinate value of the first measurement target point) is calculated. That is, the measurement point coordinate value calculator 27 calculates the above equation. In the next step 106, step 105
The measurement point coordinate value of the first measurement point calculated in step is output to the data table of the data creation unit 52 and stored. In the next step 107, the next measurement target point is set. In other words, the next measurement target point 18 and the next measurement target point 18 are obtained from the edge coordinate values of the immediately preceding measurement point (the first measurement target point in this case) at which the edge was detected immediately before and a plurality of points including the point at which the edge was detected before. The angle direction of the index 15 at the point is set. As a method of setting the measurement target point 18 in step 107, for example, there is the following method. As shown in FIG. 7, the direction from the immediately preceding measurement point 17b where the edge is detected to the immediately preceding measurement point 17a before the immediately preceding measurement point 17a where the edge is detected immediately before is set as the measurement target direction 30, and the measurement target point 18 is set as the measurement target direction 18. The measurement target direction 30 is set at a position away from the immediately preceding measurement point 17a by the measurement pitch P. The angle direction of the index 15 is set to a direction perpendicular to the measurement target direction 30. In addition to the above-described method, as another method of setting the measurement target point 18, an expected contour shape is formed by circular interpolation, spline interpolation, or the like based on the edge coordinate values of the immediately preceding measurement point and a plurality of measurement points in front of it. Alternatively, a method of setting the measurement target point 18 at a position separated from the immediately preceding measurement point 17a by the measurement pitch P on the expected contour shape may be used. In this case, the angle direction of the index 15 is set to the normal direction of the expected contour shape at the measurement target point 18. According to such a method, in step 107, the next measurement target point 18 and the angular direction of the index 15 at this point are set. Here, the immediately preceding measurement point 17a is the first measurement target point, and the immediately preceding measurement point 17b does not exist.
Therefore, in step 107, the next measurement target point (2
In order to set the (second measurement target point) 18 and the angle direction of the index 15 at this point, data indicating the measurement target direction at the first measurement target point (measurement start position) is stored in the measurement condition table 24 in advance. Have been. Using this data, the second measurement target point 18 and the angular direction of the index 15 at this point are set. After this setting, the routine proceeds to step 108. In step 108, it is determined whether or not the termination condition has been satisfied. That is, it is determined whether or not the coordinates of the next measurement target point set in step 107 have exceeded the coordinates of the measurement end position (the coordinates of the last measurement target point) captured in step 101. Here, step 1
Since the next measurement target point set in 08 is the second measurement target point, the determination result in step 108 is No, and the process returns to step 103. Steps 103 to 107 are executed, and the process proceeds to step 108.
If so, the process returns to step 103. As described above, while the determination result of step 108 is No, steps 103 to 108 are repeatedly executed, thereby moving the index 15 at regular intervals along the contour 7a of the test object 7. The measurement is performed, the coordinate values of the measurement points of each measurement point are calculated, and the calculation results are sequentially stored in the data table of the data creation unit 52. If the result of the determination in step 108 is Yes, that is, the coordinate value of the next measurement target point set in step 107 is the coordinate value of the measurement end position taken in step 101 (the coordinate value of the last measurement target point). Is exceeded, it means that the measurement of all the contour shapes 7a of the test object 7 has been completed, and thus the pre-measurement processing of FIG. 5 ends. The data creation unit 52 creates measurement instruction data indicating the position and direction of the index 15 at each measurement point from the measurement point coordinate values of each measurement point output from the pre-measurement unit 51, Output to 53. Data creation unit 52
According to the above-described method of calculating the normal direction, the direction of the index 15 at each measurement point (the index direction 40 shown in FIG. 7) is set as the normal direction of the contour shape at each measurement point. Next, the replay measurement processing (see FIG. 6) executed by the replay measurement section 53 will be described. When the replay shown in FIG. 6 is started, it is determined in step 201 whether or not all the measurement instruction data has been repeated. In other words, the measurement is repeated by using the measurement instruction data created by the data creation unit 52 from the first data (data at the measurement start position) to the last data (data at the measurement end position) in the measurement order, whereby the measurement is performed. It is determined whether the process has been completed. If the measurement instruction data that is not used remains and the measurement has not been completed, the determination result of step 201 is No, and the process proceeds to step 202. If the measurement using the last data is completed and no measurement instruction data remains, the processing is terminated. Steps 201 to 205 are repeatedly executed while the judgment result of step 201 is No. In step 202, the position of the index 15 indicated by the measurement instruction data at a certain measurement point (for example, the measurement data at the measurement start position which is the first measurement point) and the index 1 in the angular direction
Move 5 In the next step 203, the image processing unit 21
, The coordinates (edge coordinate value) of the edge point of the contour shape within the index 15 are fetched. In the next step 204, the stage coordinate value output from the stage position detector 11 and the
A coordinate value (measurement point coordinate value) of the measurement point within the index 15 is calculated based on the edge coordinate value captured in step 03. In the next step 205, step 204
Is stored in the measurement data table 25. By repeating the above steps 202 to 205, when the measurement using the last data is completed and there is no measurement instruction data, the determination result in step 201 becomes Y.
It becomes es and ends the processing. As described above, according to the one embodiment, the position of the index 15 at each measurement point is determined from the coordinate values of the measurement points at each measurement point 17 obtained by the pre-measurement (provisional measurement) of the pre-measurement unit 51. The measurement instruction data creating unit 52 creates measurement instruction data representing the direction of the index 15 (index direction 40 shown in FIG. 7) at each measurement point set in the normal direction of the contour shape, and the replay measurement unit 53 performs replay measurement (main measurement) according to the measurement instruction data. Therefore, the contour shape 7a
8, the angle direction of the index at each measurement point does not incline from the direction perpendicular to the contour 7a as shown in FIG. 8, and the index of the index at all the measurement points as shown in FIG. Edges are detected in a state where the angle direction is always perpendicular to the contour shape at the measurement target point, and there is no variation in edge detection positions. Therefore, it is possible to accurately measure the contour shape. According to the above-described embodiment, the measurement instruction data created by the measurement instruction data creation unit 52 is read out from the storage device and is used, and the replay measurement is repeated, whereby the test object 7 having the same contour shape is obtained. The measurement can be performed efficiently. In the embodiment, the pre-measurement unit 5
After detecting the coordinate values of all the measurement points by the pre-measurement (temporary measurement) by 1, the replay measurement unit 53 performs the replay measurement (main measurement), but the present invention is not limited to such a configuration. is not. For example, after the coordinate values of a plurality of measurement points are detected by the pre-measurement unit 51 and the replay measurement by the replay measurement unit 53 is repeated a plurality of times, the entire contour shape is measured. You may. As described above, according to the image measuring device of the first aspect of the present invention, the data creating section converts the edge coordinate value of each measurement point captured by the first measuring section to the edge coordinate value. Based on
Data representing the position and direction of the edge detection area at each measurement point, teaching data is created with the direction of the edge detection area at each measurement point as the normal direction of the contour shape, and the second measurement unit The contour shape is measured according to the teaching data. Therefore, even when the change in the curvature of the contour shape is large, the edge is always detected in a state where the angle direction of the index is perpendicular to the contour shape at each measurement point, and the detected position of the edge does not vary. Therefore, the measurement accuracy of the contour shape can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a schematic configuration of an image measuring device according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an image measuring device according to one embodiment. FIG. 3 is a plan view showing a test object used in the image measuring device according to the embodiment. FIG. 4 is a plan view showing a monitor screen of a monitor used in the image measuring device according to the embodiment. FIG. 5 is a flowchart showing an operation of the image measuring device according to one embodiment. FIG. 6 is a flowchart showing an operation of the image measuring device according to one embodiment. FIG. 7 is an explanatory diagram for explaining a method of setting a measurement target point and an index direction. FIG. 8 is an explanatory diagram illustrating a state in which the index is inclined. FIG. 9 is an explanatory diagram showing a state in which the index is vertical. [Description of Symbols] 5 XY stage (stage) 7 Object 7a Contour shape 12 Imaging optical system (optical system) 13 CCD camera (imaging means) 15 Index (edge detection area) 18 Measurement target point 21 Image processing unit ( Image processing means) 22 contour shape measuring section 51 pre-measuring section (first measuring section) 52 measurement instruction data creating section (data creating section) 53 replay measuring section (second measuring section)

Claims (1)

(57) [Claims] [Claim 1] Imaging which captures an image of a test object placed on a stage via an optical system and outputs an electric signal according to a light intensity distribution of the captured image. Means for detecting, by image processing based on the electric signal, an edge of a contour of the test object within an edge detection area set in an imaging range captured by the imaging means, and outputting a signal representing an edge coordinate value An image measuring device for measuring the contour shape, wherein the edge is detected while setting the position and direction of the edge detection region of each of a plurality of points along the contour shape. A first measuring unit that captures the edge coordinate value from the image processing unit at each of the measurement points, based on the edge coordinate value of each measurement point that is captured by the first measuring unit, Edge detection area position and direction And a second measurement unit that measures the contour shape in accordance with the teaching data, wherein the data creation unit determines the direction of the edge detection area at each of the measurement points. An image measuring apparatus, wherein teaching data is created with a normal direction of the contour shape at each of the measurement points.