JPH11351858A - Noncontact three-dimensional measuring equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To three-dimensionally measure a work with high precision at a high speed. SOLUTION: Two kinds of measuring means, i.e., a CCD camera 34 used in image measuring equipment, and a laser probe 35 which measures displacement in a noncontact manner by using a laser beam are arranged together, and one imaging unit 17 is constituted. The imaging unit 17 is driven in XYZ directions on the basis of the respective measured values. A work 12 is imaged in a comparatively large range by using the CCD camera 34, and the shape is measured. Fine displacement of the work where judgement of focusing is difficult is measured with the laser probe 35. By using two-dimensional information obtained by the CCD camera 34, a measuring orbit can be easily set. The laser probe 35 measures displacement amount of the work 12 along the set measuring orbit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact image measurement function for measuring a contour shape or the like of an object to be measured from an image obtained by imaging a work by an imaging means such as a CCD camera. And a non-contact three-dimensional measuring device having a non-contact displacement detecting function of detecting a distance of the non-contact as a displacement amount in a non-contact manner.

[0002]

2. Description of the Related Art Conventionally, an image measuring device has been used for measuring a contour shape of a precision part. The image measuring device captures an image of a workpiece to be measured at an arbitrary magnification using a CCD camera, detects an edge from the obtained two-dimensional image, and obtains coordinate values of a necessary portion using various measurement tools. Things. When three-dimensional measurement including the height direction of the work is performed by the image measurement device, focus determination is performed based on the contrast of the image on the measurement surface, and the focus position is set as a position in the height direction.

[0003]

In the case of a mounted component having a fine structure such as an LSI package, the manufacturing quality of the package is a major factor that determines the yield. For this reason, a device that can measure each part of the package with high accuracy is desired.
In the conventional image measurement device, the position in the height direction (Z-axis direction) is measured by focusing determination, so that a relatively large screen image is required to improve the accuracy of focusing determination. As a result, there is a problem that data processing takes time. Further, the depth of focus of the CCD camera is usually 1 to several μm, depending on the lens, and within this range, the focal point is always determined, so that there is a problem that a measurement error is large.

An object of the present invention is to provide a non-contact three-dimensional measuring device capable of three-dimensionally measuring a workpiece at high speed and with high accuracy.

[0005]

A first non-contact three-dimensional measuring apparatus according to the present invention is an image pickup means for picking up an image of a workpiece and outputting two-dimensional image information for image measurement, and a predetermined measuring point on the workpiece. An imaging unit provided with a non-contact displacement meter capable of detecting a distance from the imaging unit as a displacement amount; an imaging unit driving mechanism for driving the imaging unit to an arbitrary position in a measurement three-dimensional space; Position detecting means for outputting a position in space as a three-dimensional coordinate value; and a displacement amount outputted by the non-contact displacement meter on the work along a predetermined measurement trajectory so that the displacement amount always maintains zero or a predetermined value. And control means for controlling the imaging unit drive mechanism to move the measurement point, and taking a three-dimensional coordinate value from the position detection means to execute scanning measurement of the workpiece. .

Further, a second non-contact three-dimensional measuring apparatus according to the present invention includes an image pickup means for picking up an image of a workpiece and outputting two-dimensional image information for image measurement, and a distance from a predetermined measurement point on the workpiece. An imaging unit having a non-contact displacement meter that can be detected as a displacement amount, an imaging unit driving mechanism for driving the imaging unit to an arbitrary position in the measurement three-dimensional space, and an imaging unit driving mechanism in the measurement three-dimensional space. Position detecting means for outputting a position as a three-dimensional coordinate value, and the imaging unit for moving a measurement point on the workpiece along a predetermined measurement trajectory while fixing an axis in a displacement direction detected by the non-contact displacement meter. Control means for controlling a drive mechanism to capture a displacement amount detected by the non-contact displacement meter and three-dimensional coordinate values from the position detecting means, thereby performing scanning measurement of a workpiece. To.

According to the present invention, one image pickup unit is constructed by combining two types of measuring means, ie, an image pickup means used in an image measuring device, and a non-contact displacement meter using a laser beam or the like. This imaging unit is based on each measurement value,
It is driven by an imaging unit driving mechanism. For this reason, it is possible to measure the shape by imaging the work in a relatively large range by the imaging means, and to measure the minute displacement of the work for which focusing determination is difficult by the non-contact displacement meter. According to the present invention, the measurement trajectory can be easily set using the two-dimensional image information obtained by the imaging means, and the non-contact displacement meter measures the displacement amount of the work along the set measurement trajectory. Therefore, high-speed and high-accuracy workpiece scanning measurement becomes possible.

[0008] As a scanning measurement method, the imaging unit driving mechanism is controlled so that the displacement amount of the non-contact displacement meter always maintains zero or a predetermined value, and three-dimensional coordinate values from the position detecting means are taken in. Then, displacement measurement over a wide range that is not limited to the measurement range of the non-contact displacement meter becomes possible. Further, as a method of scanning measurement, if the axis in the displacement direction detected by the non-contact displacement type is fixed and the displacement detected by the non-contact displacement meter and the three-dimensional coordinate values from the position detecting means are taken in, the Measurement with extremely high measurement accuracy of the contact displacement meter becomes possible.

A method of automatically setting the measurement trajectory at the time of scanning measurement using a predetermined trajectory, design data, and the like can be considered. For example, an arbitrary shape such as a rectangle or a spiral is designated. It is also possible. Further, as the non-contact displacement meter, for example, a laser displacement meter that irradiates a laser beam spot on a work and receives reflected light thereof to detect a displacement amount can be used. In addition, the non-contact displacement meter irradiates a light beam onto the work through an optical system, for example, and outputs a displacement amount of the optical system at which a shift amount between a focus position and a measurement point becomes zero as a displacement amount. A focusing type displacement meter can be used.

[0010]

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 an entire configuration of a non-contact three-dimensional measuring apparatus according to one embodiment of the present invention. This apparatus includes a coordinate measuring machine 1 having a non-contact image measuring function and a non-contact displacement measuring function, and a computer system 2 which drives and controls the coordinate measuring machine 1 and executes necessary data processing. It is configured.

The coordinate measuring machine 1 is configured as follows. That is, a measurement table 13 on which the work 12 to be measured is placed is mounted on the gantry 11, and the measurement table 13 is driven in the Y-axis direction by a Y-axis driving mechanism (not shown). Support arms 14 and 15 extending upward are fixed to the center of both sides of the gantry 11.
An X-axis guide 16 is fixed so as to connect both upper ends of the support arms 14 and 15. This X-axis guide 16
Supports an imaging unit 17. The imaging unit 17 is driven along the X-axis guide 16 by an X-axis driving mechanism (not shown). Computer system 2
A computer 21 for measuring information processing and various controls;
A keyboard 22, a joystick box 23, and a mouse 24 for inputting various instruction information; a CRT display 25 for displaying a measurement screen, an instruction screen, and a measurement result;
And a printer 26 for printing out the measurement results.

The inside of the image pickup unit 17 is configured as shown in FIG. That is, the slider 31 is provided so as to be movable along the X-axis guide 16, and the Z-axis guide 32 is fixed to the slider 31 integrally. This Z-axis guide 3
2, a support plate 33 is provided slidably in the Z-axis direction,
The support plate 33 is provided with a CCD as an image pickup device for image measurement.
A camera 34 and a laser probe 35 which is a non-contact displacement meter
And are attached. Accordingly, the CCD camera 34 and the laser probe 35 maintain a fixed positional relationship between X and X.
It can be moved simultaneously in three directions of Y and Z axes. An illumination device 36 for illuminating the imaging range is added to the CCD camera 34. In the vicinity of the laser probe 35, a CCD camera 38 for imaging the periphery of the measurement position to confirm the measurement position of the laser probe 35 by the laser beam, and an illumination device 39 for illuminating the measurement position of the laser probe 35 Are provided. A vertical movement mechanism 40 for retracting the laser probe 35 when the imaging unit 17 moves;
It is supported by a rotation mechanism 41 for adjusting the directionality of the laser beam to an optimal direction.

FIG. 3 is a diagram showing details of the laser probe 35. As shown in FIG. The light emitted from the semiconductor laser 51 passes through a beam splitter 52 and a quarter-wave plate 53,
The light is collimated by the collimator lens 54 and forms a light spot on the measurement section of the work 12 via the mirrors 55 and 56 and the objective lens 57. The light reflected from the measurement section of the work 12 is reflected by the beam splitter 52 along the reverse path of the mirrors 56 and 55, the collimator lens 54 and the quarter-wave plate 53, and is vertically split by the edge mirror 58. . The light divided vertically is divided into two vertically arranged lights.
The light is detected by the divided light receiving elements 59 and 60. Detection circuit 61
Is based on the output signals from the two-divided light receiving elements 59 and 60, and from the focal position of the objective lens 57 to the measurement surface 62
And outputs a signal corresponding to the amount of deviation up to. Servo circuit 63
Outputs a drive signal for driving the objective lens 57 to the drive mechanism 64 based on the detection output of the detection circuit 61. When the objective lens 57 moves up and down, the movable member 67 of the displacement detector 66 moves with respect to the fixed member 68. This movement amount is output as a displacement amount.

FIG. 4 is a block diagram of the entire apparatus showing the configuration of the coordinate measuring machine 1 and the computer system 2 in more detail. In the coordinate measuring machine 1, image signals obtained by imaging the work 12 with the CCD camera 34 for image measurement and the CCD camera 35 for confirming the measurement position of the laser probe 35 are converted into A / D converters 71 and 7, respectively.
After being converted into multi-valued image data in 2, one of them is selected by the selection circuit 73 and supplied to the computer 21. Illumination light necessary for imaging by the CCD cameras 34 and 38 is supplied to the illumination controller 7 based on the control of the computer 21.
4,75 are provided by controlling the lighting devices 36,39, respectively. The signal of the displacement amount obtained from the laser probe 35 is supplied to the computer 21 via the A / D converter 76. Then, the imaging unit 17 including these operates under the control of the computer 21.
It is driven in the XYZ-axis directions by the YZ-axis driving unit 77.
The position of the imaging unit 17 in the XYZ-axis direction is detected by the XYZ-axis encoder 78 and supplied to the computer 21.

On the other hand, the computer 21 comprises a CPU 81 which is the center of control, a multi-value image memory 82 connected to the CPU 81, a program storage unit 83, and a work memory 8
4 and interfaces 85 and 86, and multi-valued image memory 8
The multi-valued image data stored in the CRT display 1
And a display control section 87 for displaying the image on the display 5. The CPU 81 switches the selection circuit 73 between the image measurement mode and the laser measurement mode. The multivalued image data for image measurement or the multivalued image data for laser measurement selected by the selection circuit 73 is stored in the multivalued image memory 82.
The multivalued image data stored in the multivalued image memory 82 is displayed on the CRT display 25 by the display control operation of the display control unit 87. On the other hand, operator's instruction information input from the keyboard 22, the joystick 23 and the mouse 24 is transmitted to the CPU 81 via the interface 85.
Is input to Further, the CPU 81 captures the displacement amount detected by the laser probe 35, XYZ coordinate information from the XYZ axis encoder 78, and the like. The CPU 81 stores the input information, the operator's instructions, and the program storage unit 8.
Based on the program stored in 3, various processes such as stage movement by the XYZ axis driving unit 77 and calculation processing of measured values are executed. The work memory 84 provides a work area for various processes of the CPU 81. The measured value is output to the printer 26 via the interface 86.

Next, the measurement processing and the data processing of the non-contact three-dimensional measuring apparatus according to the present embodiment configured as described above will be described. This device has an image measurement mode and a laser measurement mode. In the image measurement mode, the same operation as that of the conventional image measurement device is performed, and therefore, the laser measurement mode will be described here.

FIG. 5 is a flowchart showing the procedure of scanning measurement in the laser measurement mode. First, the image for image measurement and the laser probe 35 are calibrated (S1). That is, a jig 9 including two non-parallel linear components L1 and L2 that can be measured by a CCD camera 34 and a laser probe 35 as shown in FIG.
1 is placed. The jig 91 may be, for example, such that a trapezoidal pattern 93 having a predetermined width h is arranged on a substrate 92. CCD camera 34 and laser probe 35
The straight lines L1 and L2 are measured in the projection plane in the axial direction, the equations of these straight lines are obtained, and the obtained equations are processed to calculate the offset value between the coordinate axes of the CCD camera 34 and the laser probe 35. This offset value is used as position calibration data for the CCD camera 34 and the laser probe 35.

After the calibration process is completed, the work 12
Is image-measured to confirm the position of the work 12, and the measurement point by the laser probe 35 is moved to the measurement start point (S
2). At the time of image measurement, the laser probe 35 may interfere with the work 12. Therefore, during image measurement, the laser probe 35 is retracted upward by the vertical movement mechanism 40. The control is performed by, for example, an air cylinder. Next, when the laser measurement mode is selected (S3), the selection circuit 73
Is switched, and the screen of the CRT display 25 is CCD
The screen changes from the camera 34 to the CCD camera 38 for laser measurement. On this screen, the position (measurement position) of the laser beam spot from the laser probe 36 is confirmed (S
4). Here, the position of the beam spot can be finely adjusted using the joystick 23, the mouse 24, or the like. Since the CCD camera 38 is for confirming whether or not the laser beam spot is correctly hitting the target position on the work 12, the image data is not used for the measurement. For this reason, it is not necessary to have a high-definition camera like the CCD camera 34 for image measurement. In addition, only the position of the laser spot looks bright only with the laser light, and the surrounding area becomes dark and a clear image cannot be obtained. Of course,
The CCD camera 38 and the lighting device 39 are connected to the CCD camera 34
The lighting device 36 can also be used.

Next, in order to provide a path for scanning measurement, a measurement tool is selected and necessary parameters are set (S
5). As the measurement tool, for example, the one shown in FIG. 7 can be considered. (A) Point tool The X, Y, and Z coordinate values of the current measurement point (black circle) are measured. (B) Straight line tool The end point position Pe is given, and scanning is performed along a straight line from the current measurement point to the end point Pe. (C) Area tool Given the width W, height H, and pitches PT1 and PT2 of the area search, perform scanning measurement while reciprocating within the specified area at the specified pitch from the current measurement point. (D) Circle tool The radius R, the pitch PT, and the start angle θ are given, and the concentric circle is measured from the current measurement point. (E) Rectangular tool Given a width W and a height H, perform scanning measurement along a rectangle. (F) Cross tool Given the lengths L1 and L2 of two line segments orthogonal to each other,
Follow the cross and measure. (G) Spiral tool Maximum radius R and pitch RT (radius value increased in one rotation)
To measure the helical shape. (H) Focus tool Simply focuses at the current position.

When a measurement tool is selected and necessary parameters are set, scanning measurement is executed (S6). The displacement detection accuracy of the laser probe 35 has some directionality. Therefore, when measuring the contour and surface roughness along the track, the laser probe 3
The laser probe 35 is rotated by the rotation mechanism 41 so that 5 is oriented in the optimal direction. In the case of measuring along a circular orbit or a spiral orbit, it is more effective to measure while rotating the laser probe 35.

In the scanning measurement, the laser probe 35 is used.
In order to obtain a coordinate value in the Z-axis direction within a measurement range of, for example, ± 0.5 mm, for example, as shown in FIG.
By driving the axis driving unit 77, the position of the imaging unit 17 in the Z-axis direction is moved up and down. Thus, control is performed such that the focus position of the laser probe 35 is always at the center of the measurement range.
In this case, the Z-axis coordinate value obtained by the XYZ-axis encoder 78 is the displacement amount in the Z-axis direction. In order to perform a high-speed measurement in which the position control in the Z-axis direction cannot be performed in time, it is only necessary to correct the Z-axis coordinate value with the displacement amount of the laser probe 35 and calculate a correct displacement amount. When measuring the minute surface roughness in the measurement range of the laser probe 35, as shown in FIG. 9, the position of the laser probe 35 in the Z-axis direction is fixed,
This can be dealt with only by controlling the driving of the objective lens 57 in the laser probe 35. In this case, further high-speed processing is possible, and the resolution (for example, 0.1
μm) can be measured with a higher resolution (eg, 0.01 μm). By such scanning measurement, the coordinate values in the Z-axis direction are X and Y at predetermined intervals along the designated measurement trajectory.
The data is obtained as point sequence data together with the axis coordinate values, and is stored in the work memory 84. When the point sequence data is obtained, an analysis process of the point sequence data is executed (S7).

Next, the analysis of the point sequence data will be described. Conventional contour shape measuring instruments and surface roughness measuring instruments are two-dimensional data, whereas contour shape measuring data obtained by this non-contact three-dimensional measuring device is three-dimensional data.
Moreover, since the scanning measurement is performed along the designated two-dimensional trajectory,
Data processing becomes more complex. Therefore, in order to simplify the data processing, the following point string data analysis processing is executed. The analysis process of this point sequence data will be described based on the flowchart of FIG. 10 and the waveform diagram of FIG.

First, since the work 12 itself may be inclined, an average plane (average line in the case of a straight line) is obtained from the point sequence data, and data trend correction is performed on this plane (S11). . Thus, the trend-corrected point sequence data shown in FIG. 11B is obtained from the inclined point sequence data as shown in FIG. Next, the traveling direction along the measurement trajectory is the first axis direction, and the normal direction of the average surface is the second axis direction.
As the axial direction, the three-dimensional point sequence data is converted into two-dimensional point sequence data (S12). As a result, data as shown in FIG. 11C is obtained. Since this point sequence data is obtained by scanning with acceleration / deceleration along the measurement trajectory,
Not a constant pitch. If the pitch is not constant, Gaussian filter processing generally used in an FFT (Fast Fourier Transform) or a shape measuring instrument cannot be executed. Therefore, constant pitch processing is executed here (S1).
3: FIG. 11 (d)). Next, Gaussian filter processing is executed (S14: FIG. 11E). Then, the fixed-pitch data is returned to the original position (position of an unfixed pitch) (S15: FIG. 11 (f)). Next, two-dimensional to three-dimensional conversion for returning the two-dimensional data converted in step S12 to the original measurement trajectory position (XY position) is executed (S12).
16: FIG. 11 (g). Lastly, the inclination correction performed by the data trend correction in step S11 is restored, and the data is converted in the direction in which the work 12 is originally inclined (S17: FIG. 11 (h)).

With the above processing, filtering of the three-dimensional point sequence data can be easily performed. Further, since the data after the processing in step S14 is two-dimensional data filtered at a constant pitch, various analysis processes such as those performed by a normal contour shape measuring device or a surface roughness measuring device can be performed. become.

[0025]

As described above, according to the present invention, 2
One type of measuring means, that is, an imaging means used in an image measuring device, and a non-contact displacement meter using a laser beam or the like are provided together to form one imaging unit, and the imaging unit is configured based on each measured value. Since the apparatus is driven by the image pickup unit driving mechanism, the image pickup means performs image pickup of the work in a relatively large range to measure the shape, and on the other hand, measures the minute displacement of the work, which is difficult to determine the focus, with a non-contact displacement meter. It becomes possible. Therefore, according to the present invention, the measurement trajectory can be easily set by using the two-dimensional image information obtained by the imaging means, and the non-contact displacement meter moves the workpiece along the set measurement trajectory. Since the amount is measured, it is possible to perform high-speed and high-accuracy workpiece copying measurement.

[Brief description of the drawings]

FIG. 1 is a perspective view of a non-contact three-dimensional image measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of the inside of an imaging unit in the apparatus.

FIG. 3 is a diagram showing a configuration of a laser probe in the apparatus.

FIG. 4 is an overall block diagram of the same device.

FIG. 5 is a flowchart showing a procedure of laser measurement by the apparatus.

FIG. 6 is a view for explaining a method of calibrating an image and a laser probe in the apparatus.

FIG. 7 is a diagram showing an example of a measurement tool used in the apparatus.

FIG. 8 is a diagram for explaining an example of scanning measurement of the same apparatus.

FIG. 9 is a diagram for explaining another example of the scanning measurement of the same apparatus.

FIG. 10 is a flowchart of a point sequence data analysis process of the apparatus.

FIG. 11 is a diagram for explaining the analysis processing.

[Explanation of symbols]

1 ... three-dimensional measuring machine, 2 ... computer system, 11 ...
Stand, 12: Workpiece, 13: Measurement table, 14, 15
... Support arm, 16 ... X-axis guide, 17 ... Imaging unit, 21 ... Computer, 22 ... Keyboard, 23 ... Joystick box, 24 ... Mouse, 25 ... CRT
Display, 26 printer, 34, 38 CCD camera, 35 laser probe, 36, 39 lighting device.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takao Kawabe 1-20-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa Prefecture Mitutoyo Corporation (72) Inventor Koichi Komatsu 1-1-20, Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa No. Mitutoyo Co., Ltd. (72) Akira Sato, Inventor 1-20-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa Prefecture Mitutoyo Co., Ltd. (72) Kazuhiro Kobe 1-1-20-1, Sakado, Takatsu-ku, Kawasaki, Kanagawa Shares (72) Inventor Soichi Kadowaki 1-20-1 Sakado, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Inside System Technology Institute Co., Ltd.

Claims (7)

[Claims] 1. An image pickup device comprising: an image pickup means for picking up an image of a work and outputting two-dimensional image information for image measurement; and a non-contact displacement meter capable of detecting a distance from a predetermined measurement point on the work as a displacement amount. A unit, an imaging unit driving mechanism that drives the imaging unit to an arbitrary position in the measurement three-dimensional space, and a position detection unit that outputs a position of the imaging unit in the measurement three-dimensional space as a three-dimensional coordinate value, Controlling the imaging unit drive mechanism to move the measurement point on the work along a predetermined measurement trajectory so that the displacement amount output by the non-contact displacement meter always maintains zero or a predetermined value, A non-contact three-dimensional measuring device, comprising: a control unit that executes a scanning measurement of a workpiece by taking in three-dimensional coordinate values from a position detecting unit. 2. An image pickup apparatus comprising: an image pickup means for picking up an image of a work and outputting two-dimensional image information for image measurement; and a non-contact displacement meter capable of detecting a distance from a predetermined measurement point on the work as a displacement amount. A unit, an imaging unit driving mechanism that drives the imaging unit to an arbitrary position in the measurement three-dimensional space, and a position detection unit that outputs a position of the imaging unit in the measurement three-dimensional space as a three-dimensional coordinate value. The non-contact displacement meter detects the non-contact displacement meter by controlling the imaging unit drive mechanism to move a measurement point on the work along a predetermined measurement trajectory while fixing an axis in a displacement direction detected by the non-contact displacement meter. A non-contact three-dimensional measurement device, comprising: a control unit that executes a scanning measurement of a workpiece by taking in the displacement amount and the three-dimensional coordinate value from the position detection unit. 3. The non-contact three-dimensional measuring apparatus according to claim 1, wherein the control means executes a scanning measurement of the workpiece along a measurement trajectory specified in advance. 4. The non-contact three-dimensional measuring apparatus according to claim 3, wherein the designated measurement trajectory is a rectangle. 5. The non-contact three-dimensional measuring apparatus according to claim 3, wherein the designated measurement trajectory is spiral. 6. The non-contact displacement meter according to claim 1, wherein the non-contact displacement meter is a laser displacement meter that irradiates a laser beam spot on a workpiece and receives reflected light thereof to detect a displacement amount. The non-contact three-dimensional measuring device according to any one of the above. 7. The non-contact displacement meter irradiates a light beam onto a work through an optical system and calculates a displacement of the optical system, which makes a displacement between a focus position and a measurement point zero, to a displacement. The non-contact three-dimensional measuring apparatus according to any one of claims 1 to 6, wherein the non-contact three-dimensional measuring apparatus is a focusing type displacement meter which outputs the result as a focus.