JP3552381B2 - Image measuring machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image measuring device for measuring a contour shape of a test object.
[0002]
[Prior art]
Conventionally, as an image measuring device of this type, for example, a stage movable in two orthogonal directions and an image of a test object mounted on the stage are captured from above through an optical system, and the captured image is captured. A CCD camera that outputs an electric signal corresponding to the light intensity distribution, and detects an edge of a plurality of measurement points along the contour shape of the test object by performing image processing on the electric signal, and calculates an edge coordinate value of each measurement point. And an image processing means for outputting a representative signal.
[0003]
In this image measuring device, an image of a test object is captured by a CCD camera with a stage fixed at a certain position, and an electric signal corresponding to the light intensity distribution of the captured image is output from the CCD camera. Image processing is performed by the image processing means. The coordinate value of each measurement point is obtained from the signal output from the image processing means and representing the edge coordinate value of each measurement point, and the coordinate value of the stage.
[0004]
[Problems to be solved by the invention]
However, in the above prior art, since the image of the test object is captured by the CCD camera with the stage fixed at a certain position, only the contour shape of the test object within one image captured by the CCD camera can be measured. Can not. Therefore, when the size of the test object is large, or when the magnification of the optical system is increased in order to increase the size per pixel of the CCD camera and increase the measurement accuracy, only a part of the image of the test object is obtained. There is a problem in that it cannot be captured by a CCD camera and the measurement of the entire contour shape of the test object cannot be performed automatically.
The present invention has been made in view of such circumstances, and an object thereof is to provide an image measuring machine capable of automatically measuring the entire contour shape of a test object even when only a partial image of the test object can be captured. It is to be.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, an image measuring apparatus according to the first aspect of the present invention includes a stage movable in two orthogonal directions, and an image of a test object mounted on the stage via an optical system. An imaging unit that captures and outputs an electric signal according to a light intensity distribution of a captured image; and detects an edge of a plurality of measurement points along a contour shape of a test object by performing image processing on the electric signal to perform each measurement. Image processing means for outputting a signal representing an edge coordinate value of a point, an image measuring device for measuring the contour shape,
Stage driving means for moving the stage in the two directions based on an input movement command;
Stage coordinate detecting means for detecting coordinates of the stage and outputting a signal representing a stage coordinate value at each of the measurement points;
A detection area moving unit that moves an edge detection area within an imaging range of the imaging unit based on an input movement command;
Control means for outputting a movement command to the stage driving means and the detection area moving section so that the edge detection area sequentially moves the measurement points along the contour shape. .
[0006]
The control unit outputs a movement command to the stage driving unit and the detection area moving unit so that the edge detection area sequentially moves each measurement point along the contour shape of the test object, so that only a part of the image of the test object is output. Even when the image cannot be captured by the imaging means, the edge coordinate value of each measurement point and the stage coordinate value at each measurement point are automatically detected.
[0007]
3. The image measuring apparatus according to claim 2, wherein the control unit sets the edge detection area to the measurement target point when a measurement target point that is the next destination of the edge detection area is within the imaging range. A movement command for moving to the detection area moving unit, and when the measurement target point is located outside the imaging range, the measurement target point is located at a predetermined position within the imaging range. It is characterized in that it is configured to output a movement command for moving the stage to the stage driving means.
[0008]
When the measurement target point is within the imaging range, the edge detection area is moved to the measurement target point. Thus, while the measurement target point is within the imaging range, the edge detection area sequentially moves each measurement point along the contour shape, and the edge coordinate value of each measurement point is automatically detected.
When the measurement target point is located outside the imaging range during measurement, the stage is moved so that the measurement target point is located at a predetermined position within the imaging range, and after this movement, the edge detection area is moved to the measurement target point at the predetermined position. Move. Thereby, the measurement is continued.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 1 is a block diagram illustrating an image measuring device according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram illustrating the image measuring device.
[0011]
The image measuring device includes a measuring device main body 1 and a control unit 2 as shown in FIGS. A support 3 is provided on the measuring instrument body 1, and a monitor 4 is provided on the control unit 2.
[0012]
The measuring device main body 1 includes an XY stage 5 provided on a base 3 a of the support 3, and an imaging unit 6 supported by a support 3 b of the support 3 so as to be located above the stage 5. ing.
[0013]
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).
[0014]
As shown in FIG. 1, the XY stage 5 detects the coordinates of the XY stage 5 and the coordinates of the XY stage 5 by moving the XY stage 5 in two directions based on the input stage movement command. A stage position detector 11 for outputting a signal representing a value is provided. 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.
[0015]
The imaging unit 6 captures not only the epi-illumination optical system 9 but also an imaging optical system 12 for imaging light from the test object 7 and an image of the test object 7 formed by the optical system 12. (Receiver), and a CCD camera 13 that outputs an electric signal according to the light intensity distribution of the captured image. The magnification of the imaging optical system 12 may be fixed or variable.
[0016]
As shown in FIG. 1, the control unit 2 includes an image processing unit 21 to which an electric signal output from the CCD camera 13 is input, a contour shape measuring unit 22, an index moving unit 23, a measurement condition table 24, A measurement data table 25 and a data output unit 26 are provided. 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.
[0017]
The image processing unit 21 performs image processing on the electric signal output from each pixel of the CCD camera 13 and displays the captured image of the test object 7 on the monitor screen 4a of the monitor 4 (see FIG. 4). Is output to the monitor 4. Further, the image processing unit 21 receives the data of the index position output from the index moving unit 23, and displays the index 15 indicating the detection area of the edge at a position corresponding to the data of the index position on the monitor screen 4a. Is output to the monitor 4. 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 7a, and the data of each edge coordinate is output to the contour shape measuring unit 22. It is configured to
[0018]
The contour shape measurement unit 22 performs contour shape measurement (scanning measurement) that captures 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. It is configured. The contour shape measuring unit 22 sets a measurement target point 18 (see FIG. 6) to which the index 15 is moved in order to perform the contour shape measurement, and transmits an index movement command and a stage corresponding to the set measurement target point 18. It is configured to output a movement command to the index moving unit 23 and the XY stage driving unit 10, respectively.
[0019]
In addition, the contour shape measurement unit 22 calculates the coordinates of each measurement point based on the edge coordinate value of each measurement point output from the image processing unit 21 and the stage coordinate value in each measurement output from the stage position detection unit 11. A measurement point coordinate value calculation unit 27 that calculates a value (measurement point coordinate value) and sequentially outputs the calculation result to the measurement data table 25 is provided. The calculation unit 27 performs a calculation represented by the following equation.
[0020]
(Measurement point coordinate value) = (stage coordinate value) + (edge coordinate value x 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.
[0021]
The index moving unit 23 outputs data of an index position for moving the index 15 to the target measurement point to the image processing unit 21 based on the index moving command output from the contour shape measuring unit 22.
[0022]
The measurement condition table 24 includes data representing coordinates of a measurement start position (first measurement point) and a measurement end position (last measurement point) of the contour shape 7a of the test object 7, and an interval between the measurement points 17 (for example, a fixed value). Measurement conditions including data representing the interval) are previously input and stored by a keyboard or the like.
[0023]
The measurement data table 25 stores data of coordinate values (measurement point coordinate values) of each measurement point output from the contour shape measurement unit 22.
[0024]
The data output unit 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.
[0025]
Next, the operation of the embodiment having the above configuration will be described based on the flowchart of FIG. 5 and FIGS. 6 to 8. 6 to 8, black points indicate measurement points at which measurement has been completed, and white circles indicate measurement target points.
[0026]
When the contour shape measurement processing shown in FIG. 5 is started, in step 101, coordinate values of a measurement start position and a measurement end position which are set in advance are fetched.
[0027]
In the next step 102, the measurement start position captured in step 101 is set as the first measurement target point (for example, point P1 shown in FIG. 6).
[0028]
In the next step 103, it is determined whether or not the measurement target point set in step 102 (here, the first measurement target point) is outside the range of the monitor screen 4a. This determination is made, for example, as follows.
[0029]
Assuming that the center of the monitor screen 4a is the origin of the XY coordinates, it is determined that the set measurement target point is outside the range of the monitor screen 4a in any of the following (1) to (4). , (1) to (4), it is determined that the set measurement target point is within the range of the monitor screen 4a.
(1) When the X coordinate value (Xd) of the set coordinates (Xd, Yd) of the measurement target point becomes greater than or equal to the X coordinate value (+ Xmax) of the intersection of the right end of the monitor screen 4a and the X axis.
(2) When the X coordinate value (Xd) of the coordinates (Xd, Yd) becomes equal to or less than the X coordinate value (-Xmax) of the intersection of the left end of the monitor screen 4a and the X axis.
(3) When the Y coordinate value (Yd) of the coordinates (Xd, Yd) is equal to or greater than the Y coordinate value (+ Ymax) of the intersection of the upper end of the monitor screen 4a and the Y axis.
(4) When the Y coordinate value (Yd) of the coordinates (Xd, Yd) becomes less than or equal to the Y coordinate value (-Ymax) of the intersection of the lower end of the monitor screen 4a and the Y axis.
[0030]
If the determination result in step 103 is No, that is, if the first measurement target point (point P1 in FIG. 6) is within the monitor screen 4a, the process proceeds to step 105, and the index 15 comes to the first measurement target point (P1). The index 15 is moved as follows. At this time, an index moving command corresponding to the first measurement target point (P1) is output from the contour shape measuring unit 22 to the index moving unit 23. Data of the index position according to the index movement command is output from the index moving unit 23 to the image processing unit 21. A signal for displaying (moving) the index 15 at a position in the monitor screen 4 a corresponding to the data of the index position is output from the image processing unit 21 to the monitor 4. Thus, the index 15 is displayed at the first measurement target point (P1) on the monitor screen 4a (see FIG. 6).
[0031]
In the next step 106, the edge point coordinates of the outline shape 7a within the index 15 (the edge coordinate values of the first measurement target point (P1)) are fetched. That is, the edge coordinate values output from the image processing unit 21 are captured.
[0032]
In the next step 107, the coordinate value (measurement point) of the first measurement target point (P1) in the index 15 based on the stage coordinate value output from the stage position detection unit 11 and the edge coordinate value captured in step 106. (Coordinate values). That is, the measurement point coordinate value calculation unit 27 performs the calculation of the above equation.
[0033]
In the next step 108, the measurement point coordinate value of the first measurement target point (P1) calculated in step 107 is output to the measurement data table 25 and stored (stored).
[0034]
In the next step 109, the next measurement target point is set. At this time, data representing a certain interval between the respective measurement points 17 stored in advance in the measurement condition table is fetched, and the next measurement target point is set at a position apart from the first measurement target point (P1) by a certain interval. I do.
[0035]
After this setting, the process proceeds to the next step 110, and it is determined whether or not the end condition is satisfied. That is, it is determined whether or not the coordinates of the next measurement target point set in step 109 have exceeded the coordinate values of the measurement end position (the coordinate values of the last measurement target point) captured in step 101. Here, since the next measurement target point set in step 109 is the next point after the first measurement target point (P1), the determination result in step 110 is No, and the process returns to step 103.
[0036]
At this time, in step 103, it is determined whether or not the next measurement target point (point P2 in FIG. 6) set in step 109 is outside the range of the monitor screen 4a.
[0037]
While the determination result of step 103 is No, for example, as shown in FIG. 6, while the measurement target point 18 is on the monitor screen 4a, the above steps 103 and steps 105 to 110 are repeated to obtain the contour of the test object 7. The measurement is performed while moving the index 15 at regular intervals along the shape 7a, the coordinate values of the measurement points of each measurement point are calculated, and the calculation result is stored in the measurement data table 25.
[0038]
If the determination result of step 103 is Yes, for example, as shown in FIG. 7, measurement is performed up to point P7, and if it is determined that the measurement target point 18 is outside the monitor screen 4a, the process proceeds to step 104.
[0039]
In this step 104, the XY stage 5 is moved so that the measurement target point 18 outside the monitor screen 4a is located at the center of the monitor screen 4a. A stage movement command for performing this movement is output to XY stage drive unit 10.
[0040]
In the next step 105, the index 15 is moved so that the index 15 comes to the measurement target point 18 at the center of the monitor screen 4a. As a result of steps 104 and 105, the measurement target point 18 and the index 15 are located at the center of the monitor screen 4a as shown in FIG.
[0041]
Thereafter, by executing steps 106 to 109, the coordinate values of the measurement points of the measurement target point 18 at the center of the monitor screen 4a are calculated, and the calculation results are stored in the measurement data table 25.
[0042]
Thereafter, the process proceeds to step 110 via step 108. While the determination result of step 110 is No, the above steps 103 to 110 are repeated, measurement is performed while moving the index 15 at regular intervals along the contour shape 7a of the test object 7, and the measurement points of each measurement point are measured. The coordinate value is calculated, and the calculation result is stored in the measurement data table 25.
[0043]
If the determination result of step 110 is Yes, that is, if the coordinates of the next measurement target point set in step 109 exceed the coordinate values of the measurement end position (the coordinate values of the last measurement target point) captured in step 101, The process of FIG. 5 ends.
[0044]
As described above, according to the above-described embodiment, by moving the index 15 to the measurement target point while the measurement target point 18 is on the monitor screen 4a, the index 15 can move along the contour shape 7a of the test object 7. Then, each measurement point is sequentially moved, and the edge coordinate value of each measurement point and the stage coordinate value at each measurement point are automatically detected. When the measurement target point 18 is located outside the monitor screen 4a during the measurement, the XY stage 5 is moved so that the measurement target point 18 is located at the center of the monitor screen 4a. Move to the central measurement target point 18 in 4a, whereby the measurement is continued. Therefore, even when only a part of the image of the test object 7 can be captured, the measurement of the entire contour shape of the test object 7 can be performed automatically.
[0045]
Further, according to the above-described embodiment, even when only an image of a part of the test object 7 can be captured, the entire contour shape of the test object 7 can be automatically measured. Can be measured, and the size per pixel of the CCD camera can be increased to increase the magnification of the imaging optical system 12, thereby performing highly accurate measurement.
[0046]
Further, according to the embodiment, when the measurement target point 18 is located outside the monitor screen 4a during the measurement, the XY stage 5 is moved so that the measurement target point 18 is located at the center of the monitor screen 4a. Therefore, even if the contour shape 7a of the test object 7 measured after this movement changes in any direction, it is possible to secure a sufficient time until the measurement target point 18 is again positioned outside the monitor screen 4a.
[0047]
In the above-described embodiment, a specific method in which the contour shape measuring unit 22 controls the XY stage driving unit 10 and the index moving unit 23 so that the index 15 sequentially moves each measurement point along the contour shape 7a. As an example, while the measurement target point 18 is within the monitor screen 4a, the index 15 is moved to the measurement target point. When the measurement target point 18 is positioned outside the monitor screen 4a during measurement, the measurement target point 18 is moved to the monitor screen 4a. The XY stage 5 is moved so as to be located at the center of the inside. However, the present invention is not limited to this.
[0048]
For example, while the measurement target point 18 is within the monitor screen 4a, the index 15 is moved to the measurement target point, and when the measurement target point 18 is positioned outside the monitor screen 4a during measurement, the measurement target point 18 is displayed on the monitor screen 4a. The XY stage 5 may be moved such that the XY stage 5 is located near an end opposite to the end from which the measurement target point 18 has deviated in 4a.
[0049]
In the case of such a configuration, the time until the measurement target point 18 is located again outside the monitor screen 4a can be made longer.
[0050]
The movement of the edge detection area can be performed in a shorter time than the movement of the XY stage 5, so that the longer the measurement target point 18 is on the monitor screen 4a, the more efficiently the measurement can be performed.
[0051]
【The invention's effect】
As described above, according to the image measuring apparatus of the first aspect, the control unit controls the stage driving unit so that the edge detection area sequentially moves each measurement point along the contour shape of the test object. And the movement command is output to the detection area moving unit, so that even when only an image of a part of the test object can be captured by the imaging unit, the edge coordinate value of each measurement point and the stage coordinate value at each measurement point are automatically calculated. Is detected. Therefore, even when only a partial image of the test object can be captured, the measurement of the entire contour shape of the test object can be automatically performed.
[0052]
According to the image measuring apparatus of the second aspect, while the measurement target point is within the imaging range, the edge detection area sequentially moves each measurement point along the contour shape to perform the measurement. When the measurement target point is located outside the imaging range, the stage is moved so that the measurement target point is located at a predetermined position within the imaging range, and after this movement, the edge detection area is moved to the measurement target point at the predetermined position. Move to continue measurement. Therefore, while the measurement target point is within the imaging range, only the edge detection area need be moved without moving the stage. Therefore, even when only an image of a part of the test object can be captured, efficient automatic measurement with a short measurement interruption time can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of an image measuring device according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of the image measuring device according to the first embodiment.
FIG. 3 is a plan view showing a test object measured by the image measuring device according to the first embodiment.
FIG. 4 is a plan view showing a monitor screen of a monitor used in the image measuring device according to the first embodiment.
FIG. 5 is a flowchart showing an operation of the image measuring device according to the first embodiment.
FIG. 6 is an explanatory diagram of the operation of the image measuring device according to the first embodiment.
FIG. 7 is an operation explanatory diagram similar to FIG. 6;
FIG. 8 is an operation explanatory diagram similar to FIG. 6;
[Explanation of symbols]
5 XY stage (stage)
7 Test object 7a Contour shape 10 XY stage drive unit (stage drive means)
11 Stage position detecting section (stage coordinate detecting means)
13 CCD camera (imaging means)
15 index (edge detection area)
21 Image processing unit (image processing means)
22 Contour measurement unit (control means)
23 Index mover (detection area mover)

Claims (2)

A stage movable in two orthogonal directions, an imaging unit for capturing an image of a test object mounted on the stage via an optical system, and outputting an electric signal according to a light intensity distribution of the captured image; Image processing means for performing image processing on the electric signal, detecting edges of a plurality of measurement points along the contour shape of the test object, and outputting a signal representing an edge coordinate value of each measurement point; In an image measuring machine that measures the shape,
Stage driving means for moving the stage in the two directions based on an input movement command;
Stage coordinate detecting means for detecting coordinates of the stage and outputting a signal representing a stage coordinate value at each of the measurement points;
A detection area moving unit that moves an edge detection area within an imaging range of the imaging unit based on an input movement command;
Control means for outputting a movement command to the stage driving means and the detection area moving section so that the edge detection area sequentially moves the measurement points along the contour shape. Image measuring machine. The control means, when a measurement target point, which is the next destination of the edge detection area, is within the imaging range, sends a movement command for moving the edge detection area to the measurement target point in the detection area moving unit. And the movement command for moving the stage so that the measurement target point is located at a predetermined position within the imaging range when the measurement target point is located outside the imaging range. The image measuring device according to claim 1, wherein the image measuring device is configured to output the image to a computer.

Images