JPH11281327A - Method for measuring line width and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently measure many line widths of such as IC lead patterns. SOLUTION: When a tool is set in a picture window, scanning is started from a prescribed scanning position Ps in a prescribed scanning direction, and the edge point of a picture is detected as a first detection point P1 . Then, scanning is started from positions separated to the both sides of a direction orthogonally crossing the scanning direction only by each prescribed distance (h) to a prescribed scanning direction, and the next edges are detected as second and third detection points P2 and P3 . Then, a distance W between a straight line connecting the second and third detection points P2 and P3 and the first detection point P1 is obtained as the line width. At the time of repeating line width measurement, a cross point P5 between the straight line connecting the detected second and third detection points P2 and P3 and the initial scanning line is used as the next scanning start point Ps, and similar processing is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image measuring apparatus such as a non-contact three-dimensional measuring machine, and more particularly to a line width measuring method and apparatus capable of efficiently measuring a large number of line widths such as an IC lead pattern. .

[0002]

2. Description of the Related Art Conventional CNC (Computer Numerical Con
In a coordinate measuring machine or a manually operated coordinate measuring machine, various measured values are obtained from a work image obtained by imaging a work to be measured. In order to measure the line width, the distance between the end faces, etc., the straight line of one edge was obtained using a line measuring tool, and then the points on the other edge were measured using a point measuring tool. The distance from a straight line to a point is calculated.

[0003]

However, in the above-described conventional line width measuring method, three operations of setting a line measuring tool, setting a point measuring tool, and instructing a line-point distance calculation are required. There is a problem that the operation is complicated.
In particular, when there are a large number of line widths to be measured, such as in the case of an IC lead pattern, the above operation must be repeated many times, resulting in a problem that the measurement work efficiency is significantly reduced.

An object of the present invention is to provide a method and an apparatus for measuring a line width which can measure a line width efficiently.

[0005]

A first line width measuring method according to the present invention includes a tool setting step of setting a rectangular tool in an image window for displaying a work image obtained by imaging a work. A first scanning start point determining step in which a predetermined scanning position in the tool is set as a scanning start point, and scanning of a work image in a predetermined scanning direction from the scanning start point to change from the first level side to the second level side. A first detection step of detecting a first edge of the workpiece image and setting the first edge as a first detection point; and from a position separated by a predetermined distance from the first detection point to both sides in a direction orthogonal to the predetermined scanning direction. The second detection is performed by scanning the work image in the predetermined scanning direction, respectively, detecting first edges of the work image changing from the second level side to the first level side, and setting them as second and third detection points. Stay And a line width calculating step of obtaining a straight line passing through the detected second and third detection points and calculating a distance between the straight line and the first detection point as a line width. Features.

A second line width measuring method according to the present invention includes a tool setting step of setting a rectangular tool in an image window for displaying a work image obtained by imaging a work, and a different tool setting step. A first scanning start point determining step of setting the scanning position as a first and a second scanning start point, respectively, and scanning the work image in a predetermined scanning direction from the first and the second scanning start point to the first level side Detecting a first edge of the workpiece image, which changes from the first level to the second level side, and setting the first edge as a first and a second detection point; and re-determining the predetermined edge from the first and the second detection points. A second detection step of scanning the workpiece image in the scanning direction to detect a first edge of the workpiece image changing from the second level side to the first level side, and defining the first edges as third and fourth detection points; With obtaining the straight line passing through the third and fourth detection points are those detected, the the straight line first
And a line width calculating step of calculating a distance from a middle point of the second detection point as a line width.

Further, a first line width measuring apparatus according to the present invention provides a display means for displaying a work image obtained by imaging a work in an image window, and designates an arbitrary position in the image window. For generating a rectangular tool in the image window based on the position specified by the position specifying means, and a rectangular tool in the rectangular tool generated by the tool generating means. A workpiece image is scanned from a predetermined scanning position in a predetermined scanning direction, an edge that changes from the first level side to the second level side of the workpiece image is detected and set as a first detection point, and from this first detection point, The work image is again scanned in the predetermined scanning direction from a position separated by a predetermined distance on both sides in a direction orthogonal to the predetermined scanning direction, and the first and second work image are scanned from the second level side of the work image. Edges that change to the bell side are respectively detected to form second and third detection points, and a straight line passing through the detected second and third detection points is determined. This straight line and the first detection point are determined. And a line width detecting means for obtaining a distance from the line as a line width.

Further, a second line width measuring apparatus according to the present invention is a display means for displaying a work image obtained by imaging a work in an image window, and specifying an arbitrary position in the image window. For generating a rectangular tool in the image window based on the position specified by the position specifying means, and a rectangular tool in the rectangular tool generated by the tool generating means. The work image is scanned in a predetermined scanning direction from different scanning positions, and edges that change from the first level side to the second level side of the work image are respectively detected and the first is detected.
And a second detection point. The work image is again scanned in the predetermined scanning direction from the first and second detection points, and an edge that changes from the second level side to the first level side of the work image is detected. Detected and set as third and fourth detection points, respectively, determine a straight line passing through the detected third and fourth detection points, and determine this straight line and the middle point of the first and second detection points. And a line width detecting means for determining a distance of the line as a line width.

According to the present invention, when a tool is set in an image window, in the first method, scanning is started from a predetermined scanning position in a predetermined scanning direction, and an edge point of the image is detected as a first detection point. Then, scanning is started in a predetermined scanning direction from a position separated by a predetermined distance on both sides in a direction orthogonal to the scanning direction, and the next edge is detected as a second and a third detection point, and further, the second and third detection points are detected. The distance between the straight line connecting the three detection points and the first detection point is determined as the line width. In the second method, scanning is started from different scanning positions in a predetermined scanning direction, and edge points of an image are detected as first and second detection points, and then, from the first and second detection points. Scanning is started in each of the predetermined scanning directions, the next edge is detected as the third and fourth detection points, and a straight line connecting the third and fourth detection points and a point between the first and second detection points. The distance from the point is determined as the line width. For this reason, when measuring the line width, the operator only has to perform an operation of setting the tool so that the image to be subjected to the line width measurement is included in the image window, and the working efficiency is greatly improved.

In the first line width measuring method according to the present invention, an intersection of a straight line passing through the detected second and third detection points and a straight line extending from the predetermined scanning position in the tool in the predetermined scanning direction. May be further provided to determine the next scanning start point as the next scanning start point, and the processing after the first detection step may be repeated until the inside of the tool is completely scanned. As described above, by repeating the above processing with the intersection of the straight line connecting the second and third detection points and the straight line extending from the predetermined scanning position in the predetermined scanning direction as the next scanning start point, a large number of tools arranged in the tool can be obtained. Can be continuously measured by the same processing. Even in this case, the tool setting operation needs to be performed only once, so that the more the line width measurement targets, the higher the measurement work efficiency.

Similarly, the second line width measuring method of the present invention further includes a second scanning start point determining step in which the third and fourth detection points are set as the next first and second scanning start points. In this way, if the processing after the first detection step is repeated until the entire inside of the tool is scanned, continuous measurement can be performed for a large number of line widths arranged in the tool.

The tool setting step is a step of specifying a rectangular tool using, for example, a pointing device. In this case, if the specified tool is set out of the image window, the imaging position of the workpiece is set. The position to be designated can be positioned in the image window by sequentially changing the positions. In this way, the magnification in the image window can be made sufficiently high regardless of the size of the tool, so that the measured value can be obtained with high accuracy.

In the case of an imaging device, since the lens has the least distortion at the center of the lens, the first and second detection steps are performed such that the scanning position in the predetermined scanning direction is located at the center of the image window. The processing may be such that the imaging position for the workpiece is sequentially moved, and the edge detection position is always located at the center of the image.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the overall configuration of a CNC image measuring device according to one embodiment of the present invention. The apparatus comprises a non-contact image measurement type measuring machine main body 1 and a computer system 2 which controls the driving of the measuring machine main body 1 and executes necessary measurement data processing.
And a command input unit 3 for manually operating the measuring instrument body 1 and a printer 4 for printing out the measurement results.

The main body 1 of the measuring instrument is configured as follows. That is, the work 1 to be measured is placed on the gantry 11.
2 is mounted, and the measurement table 13 is driven in the Y-axis direction by a Y-axis drive mechanism (not shown). An upwardly extending frame 14 is fixed to the rear end of the gantry 11.
A CCD camera 16 driven by an X-axis and Z-axis driving mechanism (not shown) is attached to the inside of a cover 15 projecting from the upper part to the front so as to face the measuring table 13 from the upper part. The work 1 is located at the lower end of the CCD camera 16.
2 is provided with a ring-shaped illumination device 17 for irradiating the illumination light.

The computer system 2 includes a computer main body 21, a keyboard 22, a mouse 23, and a CRT display 24. This system centered on the computer main body 21 is configured, for example, as shown in FIG. That is, the image signal of the work 12 captured by the CCD camera 16 is converted into multi-valued image data by the AD converter 31 and stored in the multi-valued image memory 32.
The multivalued image data stored in the multivalued image memory 32 is displayed on the CRT display 24 by the operation of the display control unit 33. On the other hand, operator commands from the keyboard 22 and the mouse 23 are transmitted to an interface (I / F) 34.
Is transmitted to the CPU 35 via. The CPU 35 executes various processes such as stage movement in accordance with instructions from the operator or programs stored in the program memory 36. The work memory 37 provides a work area for various processes of the CPU 35.

An X-axis encoder 41 and a Z-axis encoder 43 for detecting the position of the CCD camera 16 in the X-axis direction and the Z-axis direction, and a Y-axis encoder 42 for detecting the position of the table 13 in the Y-axis direction. Is provided,
Outputs from these encoders 41 to 43 are taken into the CPU 35. The CPU 35 drives the CCD camera 16 in the X-axis and Z-axis directions via the X-axis drive system 44 and the Z-axis drive system 46 based on the acquired information on each axis position and the above-mentioned operator's instruction. The table 13 is driven in the Y-axis direction via the shaft drive system 45. Thus, a stage moving operation is realized. Furthermore, the lighting control unit 39
An analog command voltage is generated based on the command value generated by the PU 35 and applied to the lighting device 17.

FIG. 3 is a view showing a display screen of the CRT display 24 when the line width of the image measuring apparatus is measured. First, in the tool setting step, the work image 5 to be measured is set.
The pointer 52 is moved by clicking and dragging the mouse with respect to 1 to set a rectangular tool 53 indicating a range in which the line width is to be measured. At this time, when the tool 53 is set so as to protrude from the image window 54 for displaying the work image 51, the respective axis driving systems 44 to 46
Is driven to move the image window 54 like 54 'so as to follow the pointer 52. This makes it possible to increase the magnification of the workpiece image 51 as much as possible to increase the measurement accuracy.

When the tool 53 is set in the tool setting step, the process of FIG. 4 is started by inputting a line width measurement start instruction. FIG. 4 is a flowchart showing the processing of the CPU 35 when measuring the line width, and FIG. 5 is a view for explaining the processing. First, the scanning start point P is set at the center left end of the tool 53.
s (S1). Next, as shown in FIG. 5, an edge point of the work image 51 is detected by scanning rightward from the scanning start point Ps, and this is set as a first detection point P1 (S2). An edge point of the work image 51 is detected by scanning rightward from a point vertically separated from the first detection point P1 by a predetermined distance h, and these are detected as second and third detection points P2 and P2.
P3 (S4). The predetermined distance h is, for example, the tool 53
10% of the height. At this time, FIG.
The first detection point P1 is shifted from the first level side to the second level side, for example, from the white level to the black level so as not to detect a point on the same edge as the first detection point P1 as the second detection point P2 in. Assuming that the points are on the edge indicating the change to the level, the second and third detection points P2 and P3 are the edges indicating the change from the second level to the first level, for example, from the black level to the white level. The detection condition of the above point is added. Next, a distance W between a straight line connecting the second and third detection points P2 and P3 and the first detection point P1 is calculated (S5).

Thus, as shown in FIG. 5, the line width between edges can be correctly measured even if the edges are not completely orthogonal to the scanning direction. Detection points P2, P
Assuming that the intersection of the straight line connecting No. 3 and the straight line extending in the scanning direction from the start point Ps is P5, this P5 is the next scan start point Ps
(S6), and repeat the processing from step S2. In the course of this processing, if it exceeds the range of the tool 53, the processing ends (S3). With the above processing, the line width measurement can be repeatedly executed, and the work efficiency is greatly improved.

FIG. 6 is a flowchart of a line width measuring method according to another embodiment of the present invention, and FIG. 7 is a diagram for explaining the line width measuring method. In this embodiment, as shown in FIG. 7, edges are detected by scanning upper and lower sides of the tool 53 from the left end to the right end.

First, the left ends of the upper and lower sides of the tool 53 are set as scanning start points Ps1 and Ps2, respectively (S11). Next, as shown in FIG. 7A, the scanning start points Ps1, Ps
2 to the right to scan the first edge point P1
1, P12 are detected (S12, S13). Subsequently, scanning is performed rightward from the detected edge points P11 and P12 to detect the first edge points P21 and P22 (S
14, S15). Here, it is determined whether the level change directions (bright → dark, dark → bright) of the edge points P11 and P12 are the same (S17), and it is determined that different edges are detected as shown in FIG. 7B. To prevent. In addition, 2 in advance on the same edge
The distance L between the points P11 and P12 and the allowable value α are given as information, and it is determined whether or not the distance between the detected edge points P11 and P12 falls within the range of L ± α (S1).
8) Prevents detection of points on different edges as shown in FIG.

A straight line connecting P21 and P22 and P11 and P1
The distance W to the midpoint of the point 2 is calculated as the line width (S19).
Then, the edge point P21 is set as the next scanning start point Ps1 and the edge point P22 is set as the next scanning start point Ps2, and step S1 is performed.
Steps 2 and below are repeated (S20). If it exceeds the tool range, the process ends (S16). Steps S17 and S1
If it is determined in step 8 that an erroneous detection is made, the processing is terminated with an error message, or another error processing is executed. As described above, in the case of FIGS. 7B and 7C where the tool setting is not appropriate, an error process is performed, and erroneous detection is prevented.

In the above two embodiments, the step of detecting the edge points P1, P2, P3, P11, P12, P21, and P22 is performed by setting the stage so that the detection position is always located at the center of the image window. You should move it. This is because, in the case of an imaging device, since the lens has the least distortion at the center of the lens, highly accurate measurement is possible.

The present invention is applicable to an image in which line width patterns 61 aligned in the reference direction and line width patterns 62 and 63 inclined with respect to the reference direction are mixed, as shown in FIG. Can be dealt with by the tool 53 extending in the reference direction. When the inclination of the line width pattern to be measured with respect to the reference direction becomes large as in the pattern 63, erroneous detection (edge to be detected) can be performed by reducing the height of the tool like the tool 53 '. However, it is possible to set a tool inclined with respect to the reference direction, such as the tools 64 and 64 ', in the tool setting process.

If a graphic window 55 for displaying CAD data and the like is provided on the display screen in addition to the image window 54 as shown in FIG.
, The image window 54 can be displayed in the maximum enlarged size.

In the case of continuous line width measurement, an error range of the line width is specified in advance, and if a line width exceeding the error range is measured, a peripheral image of a predetermined size including the position is automatically determined. It is also conceivable that the illumination or focus (Z position) is controlled so that the contrast becomes maximum, and the line width is measured again. If the error still exceeds the error range, the parameters for edge detection (such as h)
The line width measurement may be continued by changing the algorithm or the algorithm.

[0028]

As described above, according to the present invention, at the time of measuring the line width, the operator only needs to set the tool so that the image to be measured is included in the image window. And the working efficiency is greatly improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a CNC image measuring device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a computer system and peripherals in the same apparatus.

FIG. 3 is a diagram showing an example of a display screen in the device.

FIG. 4 is a flowchart of a line width measurement process in the apparatus.

FIG. 5 is a diagram for explaining the line width measurement processing.

FIG. 6 is a flowchart of a line width measurement process according to another embodiment of the present invention.

FIG. 7 is a diagram for explaining the line width measurement processing.

FIG. 8 is a diagram for explaining another example of the line width measurement processing.

FIG. 9 is a diagram for explaining still another example of the line width measurement processing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Measuring machine main body, 2 ... Computer system, 3 ... Command input part, 4 ... Printer, 11 ... Base, 12 ... Work, 1
3 ... measurement table, 14 ... frame, 15 ... cover, 1
6 CCD camera, 17 lighting device, 21 computer body, 22 keyboard, 23 mouse, 24 CR
T display, 31 AD converter, 32 multi-value image memory, 33 display controller, 34 interface, 35
... CPU, 36 ... Program memory, 37 ... Work memory, 39 ... Lighting control unit, 41 ... X-axis encoder, 42 ...
Y-axis encoder, 43 ... Z-axis encoder, 44 ... X-axis drive system, 45 ... Y-axis drive system, 46 ... Z-axis drive system, 51 ... Work image, 52 ... Pointer, 53, 53 ', 64 ... Tool, 54 , 54 '... Image window.

Claims (8)

[Claims] A tool setting step of setting a rectangular tool in an image window for displaying a workpiece image obtained by imaging the workpiece; and a first scanning with a predetermined scanning position in the tool as a scanning start point. A start point determining step; scanning the work image in a predetermined scanning direction from the scan start point to detect a first edge of the work image changing from the first level side to the second level side; A first detection step of: scanning the work image again in the predetermined scanning direction from a position separated by a predetermined distance from the first detection point to both sides in a direction orthogonal to the predetermined scanning direction, and scanning the work image from the second level side The first edge of the work image that changes to the first level side is respectively detected to be a second and a third detection point.
A detecting step; and a line width calculating step of obtaining a straight line passing through the detected second and third detection points, and calculating a distance between the straight line and the first detection point as a line width. A line width measuring method characterized by the following. 2. An intersection point between a straight line passing through the detected second and third detection points and a straight line extending from the predetermined scanning position in the tool in the predetermined scanning direction is set as the next scanning start point. 2. The line width measuring method according to claim 1, further comprising a second scanning start point determining step, wherein processing after the first detecting step is repeated until the inside of the tool is completely scanned. 3. A tool setting step of setting a rectangular tool in an image window for displaying a work image obtained by imaging a work, and first and second scanning positions in the tool are set to different scanning positions, respectively.
Determining a first scanning start point to be a scanning start point, and scanning a work image in a predetermined scanning direction from the first and second scanning start points to change from the first level to the second level. A first detection step of detecting a first edge of the work image and setting the first and second detection points, respectively; and scanning the work image again in the predetermined scanning direction from the first and second detection points, respectively. A second detection step of detecting the first edge of the work image changing from the second level side to the first level side to obtain third and fourth detection points, respectively; 4. A line width calculating step of obtaining a straight line passing through the four detection points, and calculating a distance between the straight line and the midpoint of the first and second detection points as a line width. Measuring method. 4. The apparatus further comprises: a second scanning start point determining step in which the detected third and fourth detection points are used as the next first and second scanning start points. 4. The line width measuring method according to claim 3, wherein the processing after the first detecting step is repeated until the first detecting step. 5. The tool setting step is a step of designating a rectangular tool using a pointing device. If the designated tool is set out of the image window, the imaging position of the workpiece is sequentially determined. The method according to any one of claims 1 to 4, wherein the position to be designated is changed and the position to be designated is positioned in the image window. 6. The method according to claim 1, wherein the first and second detection steps sequentially move an imaging position of the workpiece so that a scanning position in the predetermined scanning direction is located at a center of the image window. The line width measuring method according to any one of claims 1 to 5. 7. A display means for displaying a work image obtained by capturing an image of a work in an image window; a position designating means for designating an arbitrary position in the image window; Tool generating means for generating a rectangular tool in the image window based on the set position, and scanning a work image in a predetermined scanning direction from a predetermined scanning position in the rectangular tool generated by the tool generating means. An edge that changes from the first level side to the second level side of the work image is detected as a first detection point, and a predetermined distance from the first detection point to both sides in a direction orthogonal to the predetermined scanning direction. The workpiece image is again scanned in the predetermined scanning direction from a position separated by just a distance, and edges that change from the second level side to the first level side of the workpiece image are respectively detected. Then, a straight line passing through the detected second and third detection points is obtained, and a line between the straight line and the first detection point is obtained as a line width. A line width measuring device comprising a width detecting means. 8. A display means for displaying a work image obtained by imaging a work in an image window, a position designating means for designating an arbitrary position in the image window, and designation by the position designating means. Tool generating means for generating a rectangular tool in the image window based on the set position, and scanning the work image in a predetermined scanning direction from a different scanning position in the rectangular tool generated by the tool generating means. And the second from the first level side of the work image
Edges that change to the level side are respectively detected to form first and second detection points, and the work image is again scanned in the predetermined scanning direction from the first and second detection points, respectively, and the first and second detection points are scanned. Edges changing from the second level to the first level are respectively detected to form third and fourth detection points, and a straight line passing through the detected third and fourth detection points is obtained. A line width detecting unit for obtaining a distance from a middle point of the first and second detection points as a line width.