JP6908206B1 - Shape measuring device, shape measuring system, shape measuring method and shape measuring program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately or easily measure a position of a surface of a work. Before measuring the position of a surface 81 of a measurement work 80, a coefficient calculation unit 32 calculates a conversion coefficient K with reference to a reference work image 99, and a reference coordinate measurement unit 33 calculates a reference work image 99. The reference coordinate value RP1p corresponding to the reference position RP1 is measured with reference to. When measuring the position of the surface 81 of the measuring work 80, the displacement information acquisition unit 34 provides surface displacement information indicating the distance ΔZ1 from the reference position RP1 in the normal direction of the surface 81 of the measuring work 80 to the surface 81 of the measuring work 80. get. The measurement surface calculation unit 35 converts the distance ΔZ1 into the surface displacement pixel amount Δy1 using the conversion coefficient K. The measurement surface calculation unit 35 calculates the surface coordinate value y81 representing the position of the surface 81 of the measurement work 80 on the measurement work image 89 by correcting the reference coordinate value RP1p with the surface displacement pixel amount Δy1. [Selection diagram] Fig. 4

Description

The present invention relates to an apparatus, system, method and program for measuring the shape of a side end portion of a plate-shaped workpiece.

In a plate-shaped work, stress concentration occurs at the corner portion formed by the front surface or the back surface and the side surface. When the work is made of a brittle material such as glass, sapphire, silicon or ceramics such as a semiconductor wafer or a substrate for a liquid crystal display, the corners are easily damaged by stress concentration. Generally, in the manufacturing process of such a work, chamfering is performed on the corner portion in order to prevent damage.

"Beveling" includes C chamfering and R chamfering. In the chamfering process, the corners are cut off by polishing or laser processing. As a result, at the side end portion of the work, the front surface or the back surface is continuous with the side surface via the bevel surface (an inclined surface having a straight cross section or a curved surface having an arc cross section). Alternatively, the front bevel surface is continuous with the back bevel surface without leaving any side surface, and the front surface and the back surface are continuous with each other via the integrated bevel surface. In this document, unless otherwise specified, the "bevel portion" refers to the bevel surface left on the side end portion of the work after chamfering and the portion inside the bevel surface.

After chamfering, the shape of the bevel portion is measured. As a result, the appropriateness of the chamfering process is inspected, and the quality of the work is judged. As an example of a method for measuring the shape of the side end of a plate-shaped workpiece, a so-called "optical projection measurement method" is known in accordance with the standard (SEMI Standard) set by an industry group involved in semiconductor manufacturing (SEMI Standard). For example, see Patent Document 1).

In the optical projection measurement method, illumination light is emitted from a direction parallel to the surface of the work (semiconductor wafer), the side end of the work is imaged from the direction facing the illumination, and the shape of the side end of the work is displayed on the image. Measured at. In order to measure the shape, it is necessary to specify the contour of the work on the image.
However, since both the front side and the back side of the camera on the front and back sides are within the field of view of the camera, the images on the front and back sides are blurred. When the work is made of a material having high light transmission (transparency) such as glass, the degree of this blurring becomes large.

Therefore, in Patent Document 1, the optical path length of light along the side end portion of the work is derived. The optical path length is the depth dimension in the light projection direction from the front end of the side end of the camera to the back end of the camera. Based on the finding that the depth dimension is proportional to the degree of blur, the contours of the front and back surfaces are specified on the blurred image, and the degree of blur is estimated according to the depth dimension. The positions of the front and back surfaces are estimated by back-calculating the degree of blur from the specified contour.

Japanese Patent No. 4316643

In the conventional measurement method, the positions of the front surface and the back surface are estimated only by referring to the image. However, it is difficult to accurately identify the outline of a blurred image. The degree of blurring also depends on various factors other than the depth dimension, for example, the material properties of the work such as light transmission, the amount of illumination light, and the depth of field. Therefore, it is difficult to accurately estimate the degree of blurring based on the depth dimension.

As described above, it is considered that there is room for improvement in the method of measuring the shape of the work based on the imaging result in terms of accuracy and simplicity.
Therefore, an object of the present invention is to accurately or easily measure the position of the surface of the work.

The shape measuring device according to one embodiment of the present invention measures the shape of the side end portion of a plate-shaped measuring work having a front surface and a back surface. The shape measuring device includes an image acquisition unit, a coefficient calculation unit, a reference coordinate measurement unit, a displacement information acquisition unit, and a measurement surface calculation unit.
The image acquisition unit acquires a reference work image generated by imaging the reference plane of the reference work using the imaging device from the imaging device. Further, the image acquisition unit acquires a measurement work image generated by imaging the side end portion of the measurement work from one direction parallel to the surface of the measurement work using the image pickup device.

The coefficient calculation unit calculates the reference dimension pixel amount corresponding to the predetermined dimension of the reference work in the image coordinate system defined on the image based on the reference plane on the reference work image, and actually measures the predetermined dimension. And the reference dimension pixel amount, a conversion coefficient representing the pixel amount corresponding to the unit distance is calculated. The reference coordinate measuring unit refers to the reference work image and measures the reference coordinate value in the image coordinate system corresponding to the predetermined reference position set on the reference work.

The displacement information acquisition unit acquires surface displacement information indicating the distance from the reference position to the surface of the measurement work in the plate thickness direction of the measurement work. The measurement surface calculation unit converts the distance indicated by the surface displacement information into the surface displacement pixel amount using a conversion coefficient. Further, the measurement surface calculation unit calculates the surface coordinate value representing the position of the surface of the measurement work on the measurement work image by correcting the reference coordinate value with the surface displacement pixel amount.

In the above configuration, the above-mentioned light projection measurement method is used to measure the shape of the side end portion of the plate-shaped measuring work having the front surface and the back surface. However, the measurement surface calculation unit does not adopt a method of specifying the contour of the blurred surface on the measurement work image and estimating the position of the surface from the specified contour.
In the image coordinate system defined on the image, the reference coordinate value corresponding to the predetermined reference position is measured in advance. A conversion coefficient (pix / mm) representing the amount of pixels in the image coordinate system corresponding to the unit distance is calculated in advance. Then, instead of specifying the contour on the measurement work image, the distance from the reference position to the surface of the measurement work is measured. This distance is converted into the pixel amount (surface displacement pixel amount) in the image coordinate system using the conversion coefficient. In the space where the measurement work is installed, if the surface of the measurement work is separated from the reference position by the measured distance (mm), the surface is displaced from the reference coordinate value on the measurement work image. Only (pix) away. The measurement surface calculation unit calculates the surface coordinate value by correcting the reference coordinate value with the surface displacement pixel amount.

According to the above configuration, the position of the surface is specified by using the surface displacement pixel amount converted from the measured distance. Blurred measurement Compared with the case of estimating the surface position only by referring to the work image, the surface position can be measured accurately and easily.
Further, in the above configuration, the image acquisition unit acquires the reference work image in order to obtain the conversion coefficient and the reference coordinate value. The reference work image is generated by imaging the reference plane of the reference work.

The coefficient calculation unit calculates the reference dimension pixel amount based on the reference plane on the reference work image. The reference dimension pixel amount is the pixel amount in the image coordinate system defined on the image, and corresponds to a predetermined dimension of the reference work. This predetermined dimension has been measured, that is, is known. The conversion coefficient is calculated from the reference dimension pixel amount and the measured value. For example, if the reference dimension pixel amount is 200 pix and the measured value is 5 mm, the conversion coefficient (pixel amount per unit distance) is 40 pix / mm.

The reference coordinate measuring unit measures the reference coordinate value with reference to the reference work image. The reference coordinate value is a coordinate value defined in the image coordinate system, and corresponds to a reference position set in the space where the reference work or the measurement work is installed. The reference position is set on the reference work. The reference coordinate measuring unit measures the reference coordinate value on the reference work image.
In this way, by referring to the reference work image, the conversion coefficient and the reference coordinate value can be obtained before measuring the position of the surface of the measurement work. The above-mentioned method for calculating the surface coordinate value can be realized.

In addition, the imaging device images the reference plane of the reference work. That is, when the reference work is imaged, the reference work does not exist on the image pickup device side of the reference plane of the reference work. Therefore, the reference work image is less likely to be blurred than the measurement work image. The image of the reference plane becomes clear. Therefore, the calculation accuracy of the reference dimension pixel amount and the conversion coefficient becomes high. In addition, the measurement accuracy of the reference coordinate value corresponding to the reference position is improved. Since these accuracy is high, the calculation accuracy of the surface coordinate value is high.

The "measurement work" may be any plate-shaped work such as a semiconductor wafer and a substrate for a liquid crystal display. Even when the measuring work is made of a transparent material such as glass and the image of the measuring work is easily blurred, the position of the surface of the measuring work can be measured accurately.
The reference work may have a reference plane capable of identifying the contour of the reference work on the reference work image captured by the imaging device.

According to the above configuration, the coefficient calculation unit and the reference coordinate measurement unit can identify the contour of the reference work and execute the process. Therefore, the accuracy of the conversion coefficient and the reference coordinate value is improved, and the measurement accuracy of the surface position is improved.
The reference work may be made of a material having a lower light transmittance than the measurement work.
According to the above configuration, since the material of the reference work has low light transmittance, the reference work image is less likely to be blurred. Therefore, the accuracy of the conversion coefficient and the reference coordinate value is improved, and the measurement accuracy of the surface position is improved.

The reference work may be formed in a plate shape having a front surface and a back surface, and may have a uniform plate thickness. The reference surface may connect the front surface and the back surface in the plate thickness direction of the reference work, and the contour of the reference surface may be formed by the front surface and the back surface. The predetermined dimension of the reference work may be the plate thickness of the reference work.
In the above configuration, the contour of the reference surface is formed by the front surface and the back surface, and the amount of pixels between the front surface image and the back surface image on the reference work image corresponds to the plate thickness of the reference work. Since the image of the reference plane is clear as described above, the coefficient calculation unit can accurately calculate the pixel amount corresponding to the plate thickness as the reference dimension pixel amount. Therefore, the accuracy of the conversion coefficient is improved.

The coefficient calculation unit may calculate a reference surface coordinate value representing the position of the front surface of the reference work on the reference work image and a reference back surface coordinate value representing the position of the back surface of the reference work. The coefficient calculation unit may calculate the reference dimension pixel amount based on the reference front surface coordinate value and the reference back surface coordinate value.
In the above configuration, the reference dimension pixel amount is calculated based on the reference front surface coordinate value and the reference back surface coordinate value. Since the front surface image and the back surface image of the reference work are clear, the reference front surface coordinate value and the reference back surface coordinate value can be easily specified. Therefore, the reference dimension pixel amount can be calculated accurately and easily.

The reference position may be set on the front surface or the back surface of the reference work in a state where the reference work is imaged by using the imaging device. The reference coordinate measuring unit may determine the reference front coordinate value or the reference back surface coordinate value as the reference coordinate value.
According to the above configuration, since the reference position is set on the front surface or the back surface of the reference work, the reference front surface coordinate value or the reference back surface coordinate value measured at the time of calculating the reference dimension pixel amount is diverted as the reference coordinate value. Can be done. It is possible to simplify the processing executed by referring to the reference work image.

The displacement information acquisition unit may acquire back surface displacement information indicating the distance from the reference position to the back surface of the measurement work in the plate thickness direction of the measurement work. The measurement surface calculation unit may convert the distance indicated by the back surface displacement information into the back surface displacement pixel amount using a conversion coefficient. The measurement surface calculation unit may calculate the back surface coordinate value representing the position of the back surface of the measurement work on the measurement work image by correcting the reference coordinate value with the back surface displacement pixel amount.

According to the above configuration, the position of the back surface of the measurement work can be accurately and easily measured on the measurement work image in the same manner as the front surface.
The shape measuring device may further include an image processing unit that measures the shape of the bevel portion provided at the side end portion on the measurement work image based on the surface coordinate values.
According to the above configuration, since the position of the surface is accurately measured, the image processing unit can accurately measure the shape of the bevel portion.

The shape measuring system according to one embodiment of the present invention includes the above-mentioned shape measuring device, an imaging device, and a first displacement sensor. The image pickup apparatus captures the measurement work and generates a measurement work image. Further, the image pickup apparatus captures the reference work and generates a reference work image. The first displacement sensor measures the distance from a predetermined reference position to the surface of the measuring work in the plate thickness direction of the measuring work, and outputs surface displacement information.

The system has the same or corresponding technical features as the technical features of the shape measuring device. Therefore, the position of the surface of the measuring work can be measured accurately and easily.
The focus of the image pickup device may be located on the reference plane of the reference workpiece.
According to the above configuration, the reference plane is clearly projected on the reference work image. Therefore, the accuracy of the conversion coefficient and the reference coordinate value is improved.

The image pickup apparatus may image the reference work from a direction substantially orthogonal to the reference plane of the reference work. The reference plane may be superposed on the focal plane of the imaging device.
A "focal plane" is a plane that passes through the focal point on the optical axis and is perpendicular to the optical axis. The reference plane is superposed on the focal plane, and the imaging device images the reference plane from a direction orthogonal to the reference plane, so that the entire reference plane is clearly projected on the reference work image. Therefore, the accuracy of the conversion coefficient and the reference coordinate value is improved.

The position, posture, and magnification of the imaging device may be set to be the same when the reference work is imaged and when the measurement work is imaged.
According to the above configuration, since the magnification is not changed, the pixel amount corresponding to the actual distance on the reference work image and the pixel amount corresponding to the actual distance on the measured work image are the same. Since the position and orientation are not changed, the reference coordinate values measured on the reference work image have the same coordinate values in the image coordinate system in the measured work image. Complicated coordinate conversion processing between the reference work image and the measurement work image becomes unnecessary, and the position of the surface can be measured accurately and easily.

In a state where the reference work is imaged, the first displacement sensor may be calibrated so that the measured distance value becomes zero at the reference position on the reference work.
According to the above configuration, since the distance measurement value of the first displacement sensor is calibrated so as to be a zero value at the reference position, the distance from the reference position to the surface of the measurement work can be accurately measured.
The shape measuring system may further include a second displacement sensor that measures the distance from the reference position to the back surface of the measuring workpiece in the plate thickness direction of the measuring workpiece and outputs backside displacement information indicating the measurement result. The measurement surface calculation unit may convert the distance indicated by the back surface displacement information into the back surface displacement pixel amount using a conversion coefficient. The measurement surface calculation unit may calculate the back surface coordinate value representing the position of the back surface of the measurement work on the measurement work image by correcting the reference coordinate value with the back surface displacement pixel amount.

According to the above configuration, the positions of both the front surface and the back surface can be accurately measured on the measurement work image by using the first displacement sensor and the second displacement sensor.
The shape measuring method according to one embodiment of the present invention measures the shape of the side end portion of a plate-shaped measuring work having a front surface and a back surface. The shape measuring method includes a reference work image acquisition step, a coefficient calculation step, a reference coordinate measurement step, a measurement work image acquisition step, a displacement information acquisition step, and a measurement surface calculation step.

In the reference work image acquisition step, the reference work image generated by imaging the reference plane of the reference work using the imaging device is acquired from the imaging device. In the coefficient calculation step, based on the reference plane on the reference work image, the reference dimension pixel amount corresponding to the predetermined dimension of the reference work is calculated in the image coordinate system defined on the image, and the measured value of the reference work. And the reference dimension pixel amount, a conversion coefficient representing the pixel amount corresponding to the unit distance is calculated. In the reference coordinate measurement step, the reference coordinate value in the image coordinate system corresponding to the predetermined reference position set on the reference work is measured with reference to the reference work image.

In the measurement work image acquisition step, the measurement work image generated by imaging the side end portion of the measurement work from one direction parallel to the surface of the measurement work is acquired from the image pickup device. In the displacement information acquisition step, surface displacement information indicating the distance from the reference position to the surface of the measurement work in the normal direction of the surface of the measurement work is acquired. In the measurement surface calculation step, the distance indicated by the surface displacement information is converted into the surface displacement pixel amount using the conversion coefficient, and the reference coordinate value is corrected by the surface displacement pixel amount to measure on the measurement work image. The surface coordinate value representing the position of the surface of the work is calculated.

The shape measurement program according to one embodiment of the present invention causes a computer to execute the above shape measurement method.
The above method and program have the technical features corresponding to the technical features of the above shape measuring device. Therefore, the position of the surface of the measuring work can be measured accurately and easily.

According to the present invention, the position of the surface of the work can be measured accurately and easily.

It is a top view which shows the shape measurement system which concerns on embodiment of this invention. It is a top view which shows the shape measuring system in the state where the measuring work is installed. It is a side view which shows the shape measuring system in the state which the measuring work is installed. It is sectional drawing of the side end part of the measuring work along the line III-III of FIG. It is a block diagram which shows the shape measuring apparatus which concerns on embodiment of this invention. It is a flowchart which shows the shape measurement method which concerns on embodiment of this invention. It is a top view which shows the shape measurement system in the state which the reference work is installed. It is a side view which shows the shape measurement system in the state which the reference work is installed. It is a figure which shows the reference work image. It is explanatory drawing of the zero reset process. It is a figure which shows the measurement work image. It is explanatory drawing of the process of measuring the distance with respect to the reference position of the surface of the measuring work. It is a figure which shows an example of the side end measurement image. It is a perspective view which shows the reference work.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or corresponding elements are designated by the same reference numerals throughout the drawings, and duplication of detailed description is omitted.
1 and 2 show a shape measuring system 1 according to an embodiment of the present invention. The shape measuring system 1 measures the shape of the side end portion 83 of the plate-shaped measuring work 80 having the front surface 81 and the back surface 82.

(Measurement work)
A semiconductor wafer or a glass wafer is a good example of the measuring work 80. The wafer has a disk shape. The front surface 81 and the back surface 82 are circular flat surfaces and are parallel to each other. The material of the measuring work 80 is not particularly limited. Unless otherwise specified, the measuring work 80 is a glass wafer in this embodiment. Glass is brittle and has high light transmission.

FIG. 3 shows a cross section of the side end portion 83. The side end portion 83 is chamfered. In the present embodiment, R chamfering is performed on both the corner portion 88a formed by the front surface 81 and the side surface 87 and the corner portion 88b formed by the back surface 82 and the side surface 87. By excising the corner portion 88a, a front side bevel portion 84a is provided on the surface side of the side end portion 83. By cutting the corner portion 88b, a back side bevel portion 84b is provided on the back surface side of the side end portion 83. These bevel portions 84a and 84b form a bevel surface having a 1/4 arc-shaped cross section. The bevel surface on the front side and the bevel surface on the back side are continuous with each other. The front surface 81 is continuous with the back surface 82 via a bevel surface having an integrated semicircular cross section. The side edge edge (the edge farthest from the center) of the measuring work 80 is formed at a point where the two bevel surfaces meet.

By this chamfering process, the corner portions 88a and 88b are cut off from the side end portions 83 without leaving the side surface 87. Therefore, even if the measuring work 80 is made of a brittle material, the stress concentration at the side end portion 83 is relaxed and the measuring work 80 is suppressed from being damaged.
The shape measuring system 1 is suitably applied at the manufacturing site of the measuring work 80 (glass wafer). By measuring the shape of the side end portion 83 using the shape measuring system 1, it is possible to support the inspection of the appropriateness of the chamfering process and the judgment of the quality of the measuring work 80.

(Shape measurement system)
With reference to FIGS. 1 and 2, the shape measuring system 1 includes a lighting device 2, an imaging device 3, a first displacement sensor 4, a second displacement sensor 5, and a shape measuring device 10. The work support device 11, the work position sensor 12, the attitude control device 13, the lighting support jig 14, the camera support jig 15, and the sensor support jig 16 may be devices constituting the shape measurement system 1, and shape measurement may be performed. It may be an external device that cooperates with or cooperates with the system 1.

The lighting device 2, the image pickup device 3, the first displacement sensor 4, the second displacement sensor 5, the work support device 11, the work position sensor 12, the lighting support jig 14, the camera support jig 15, and the sensor support jig 16 are measured. It is located in the workspace for performing operations.
The direction in the workspace is defined in the orthogonal three-dimensional spatial coordinate system CS1. The X and Y directions of the spatial coordinate system CS1 are orthogonal to each other in the horizontal plane. The Z direction of the spatial coordinate system CS1 is the vertical direction.

(Work support device)
The work support device 11 is supported on the floor surface of the work space. The work support device 11 has a rotary table 11a on which the measuring work 80 is placed. The measuring work 80 is supported on the rotary table 11a in a horizontal posture. That is, the front surface 81 and the back surface 82 form a horizontal plane. The plate thickness direction of the measuring work 80 (normal direction of the front surface 81 and the back surface 82) coincides with the vertical direction (Z direction). In the present embodiment, the front surface 81 is directed upward to form an upper surface, and the back surface 82 is directed downward to form a lower surface.

The rotary table 11a rotates around a rotation axis directed in the vertical direction (Z direction). The disk-shaped measuring work 80 is positioned in the horizontal direction so that its center is coaxial with the rotation axis, and is placed on the rotary table 11a. The measuring work 80 rotates concentrically with the rotary table 11a.
The work position sensor 12 detects an orientation indicating unit (for example, a notch, an orientation flat, etc.) (for example, a notch, an orientation frame, etc.) provided on the measuring work 80. The orientation indicating unit is provided on the measuring work 80 at the time of chamfering. The work position sensor 12 may be attached anywhere as long as it does not rotate integrally with the rotary table 11a.

The attitude control device 13 detects the rotational position of the measurement work 80 from the detection result of the work position sensor 12. The attitude control device 13 operates and stops the actuator of the rotary table 11a to control the attitude (rotational position around the vertical axis) of the measuring work 80.

(Lighting device)
The lighting device 2 has a light source that emits illumination light. The illuminating device 2 may have a mask that restricts the passage of the illuminating light and a lens that parallelizes the illuminating light.
The lighting device 2 is supported by the lighting support jig 14, and is arranged in the work space at a predetermined position in the work space in a predetermined posture. The lighting device 2 irradiates the illumination light in one horizontal direction (X direction). The optical axis of the illumination light passes over the side end portion 83 of the measuring work 80 in a plan view. The optical axis of the illumination light is positioned at substantially the same position as the central portion in the plate thickness direction of the measuring work 80 in the vertical direction.

(Imaging device)
The image pickup device 3 includes an image pickup device and an imaging optical system that collects light from a subject and forms an image on the image pickup device. The subjects are, for example, the side end portion 83 of the measurement work 80 and the reference work 90 (see FIG. 6). The imaging optical system is composed of a plurality of lenses. The image pickup device is composed of a plurality of photoelectric conversion elements (for example, CCD, CMOS, etc.).

The image pickup apparatus 3 is supported by the camera support jig 15 and is arranged in the work space at a predetermined position in the work space in a predetermined posture. The image pickup device 3 faces the illumination device 2 in the above one direction (X direction). The optical axis of the imaging optical system is parallel or coaxial with the optical axis of the illumination light. The optical axis of the imaging optical system passes over the side end portion 83 of the measuring work 80 in a plan view, and is positioned at substantially the same position as the central portion in the plate thickness direction of the measuring work 80 in the vertical direction.

The focal point of the imaging optical system is set on a straight line passing through the rotation axis of the work support device 11 (that is, the center of the disk-shaped measuring work 80). This straight line extends in the direction orthogonal to the optical axis (Y direction) in a plan view. Hereinafter, the plane passing through the focal point on the optical axis and perpendicular to the optical axis is referred to as a "focus plane FP". The focal plane FP extends in the direction orthogonal to the optical axis (Y direction) in a plan view and extends in a vertical direction (Z direction) in a side view.

Each photoelectric conversion element forms a pixel. The plurality of photoelectric conversion elements are arranged in a matrix on the light receiving surface perpendicular to the optical axis. The positions of the plurality of photoelectric conversion elements (pixels) are defined in the orthogonal two-dimensional image coordinate system CS2 set on the light receiving surface. In the present embodiment, the horizontal axis x of the image coordinate system CS2 corresponds to the Y direction of the spatial coordinate system CS1. The vertical axis y of the image coordinate system CS2 corresponds to the Z direction of the spatial coordinate system CS1.
The image pickup apparatus 3 images a subject from one direction (X direction) parallel to the surface 81 of the measurement work 80 and in the direction opposite to the illumination light. The light from the subject is imaged on the image sensor via the imaging optical system. Each photoelectric conversion element converts the amount of received light into the amount of electric charge. The image pickup apparatus 3 generates image data based on the amount of electric charge of each pixel.

(Measurement work image)
FIG. 10 shows image data generated by imaging the side end portion 83 of the measurement work 80 using the image pickup apparatus 3, that is, the measurement work image 89. With reference to FIGS. 1 and 10, a front surface 81 and a back surface 82 are imaged on the image sensor together with the bevel portions 84a and 84b. The position of the image represented on the measurement work image 89 is defined in the image coordinate system CS2.

In the Y direction of the spatial coordinate system CS1, that is, in the x direction of the image coordinate system CS2, the depth of the front surface 81 and the back surface 82 with respect to the focal plane FP increases as the distance from the side end portion 83 approaches the center. The "depth" is the length (chord length) of the front surface 81 and the back surface 82 in the optical axis direction (X direction).
The side edge of the measuring work 80 does not have this depth. Even if the depth of field is shallow, the image at the side edge will be clear. The closer to the center, the more light from the portion of the surface 81 that is farther from the focal plane FP is imaged on the image sensor, so that the image of the surface 81 is blurred more in the vertical axis y direction. The same applies to the back surface 82.

(Displacement sensor)
With reference to FIGS. 1 and 2, the first displacement sensor 4 emits a measurement medium such as ultrasonic waves or light, and inputs the reflection of the measurement medium from the measurement object. The first displacement sensor 4 measures the distance from itself to the object to be measured in the ejection direction of the measurement medium based on the input result. The measurement principle is not particularly limited, and may be a triangulation type or a time-of-flight type. The "distance" can be defined in the spatial coordinate system CS1 and is, for example, a millimeter (mm) value. The second displacement sensor 5 is also configured in the same manner as the first displacement sensor 4.

The first displacement sensor 4 and the second displacement sensor 5 are supported by the sensor support jig 16 and are arranged in the work space at a predetermined position in the work space in a predetermined posture. The directions with respect to the first displacement sensor 4 and the second displacement sensor 5 (for example, the ejection direction of the measurement medium) are originally defined in the sensor coordinate system, but the sensor coordinate system is spatially coordinated by the sensor support jig 16. Aligned with respect to system CS1. Therefore, for convenience, the sensor coordinate system will be described below by equating it with the spatial coordinate system CS1.

The first displacement sensor 4 is arranged so as to face the surface 81 in the vertical direction (Z direction). The second displacement sensor 5 is arranged so as to face the back surface 82 in the vertical direction (Z direction). The first displacement sensor 4 and the second displacement sensor 5 are positioned near the focal plane FP in the horizontal plane.
The first displacement sensor 4 is supported in a posture of ejecting the measurement medium in the normal direction of the surface 81. The second displacement sensor 5 is supported in a posture in which the measurement medium is ejected in the normal direction of the back surface 82. In the present embodiment, the front surface 81 and the back surface 82 are horizontal, and both injection directions are in the vertical direction (Z direction).

The first displacement sensor 4 has a so-called "zero reset function". For example, the distance to a certain measurement object is measured in advance using the first displacement sensor 4. Then, the position of the object to be measured is set as a reference value (zero value). The position and orientation of the first displacement sensor 4 are maintained in the state in which the measurement for setting the reference value is performed. After that, when the first displacement sensor 4 measures the distance to another measurement object, the first displacement sensor 4 replaces the distance from the first displacement sensor 4 to the other measurement object from the reference value. The distance to the position of the other measurement object (displacement amount with respect to the reference value) is output as the distance measurement value. The second displacement sensor 5 also has this zero reset function. The zero reset will be described later with reference to FIG.

(Shape measuring device)
With reference to FIG. 4, the shape measuring device 10 is connected to a lighting device 2, an imaging device 3, a first displacement sensor 4, a second displacement sensor 5, and an attitude control device 13.
The shape measuring device 10 is realized by a computer having a CPU, a memory, and an input / output interface. This "computer" may be a single computer or a composite of a plurality of physically distributed computers. The memory stores a shape measurement program for causing such a computer to execute a shape measurement method (see FIG. 5). The CPU reads the shape measurement program stored in the memory and performs information processing related to the shape measurement method according to the shape measurement program. In addition to the shape measurement program, the memory can also temporarily store information or data necessary for executing the shape measurement method.

By executing the shape measurement program, the shape measuring device 10 executes a storage unit 20, a lighting control unit 21, a camera control unit 22, a sensor control unit 23, a posture control unit 24, an image acquisition unit 31, a coefficient calculation unit 32, and a reference. It has a coordinate measurement unit 33, a displacement information acquisition unit 34, a measurement surface calculation unit 35, and an image processing unit 36. When the shape measuring device 10 is a composite of a plurality of distributed computers, each part may be realized in any computer.

The storage unit 20 is realized by the above-mentioned memory. The storage unit 20 stores the conversion coefficient K calculated by the coefficient calculation unit 32 and the reference coordinate value measured by the reference coordinate measurement unit 33. In the present embodiment, the reference coordinate value includes the front side reference coordinate value RP1p and the back side reference coordinate value RP2p.
The lighting control unit 21 controls the operation of the lighting device 2. The camera control unit 22 controls the operation of the image pickup device 3. The sensor control unit 23 controls the operation of the first displacement sensor 4 and the second displacement sensor 5. The attitude control unit 24 controls the operation of the work support device 11 via the attitude control device 13. As a result, the posture control unit 24 controls the posture of the work (measurement work 80 and reference work 90) supported by the rotary table 11a around the vertical axis.

The image acquisition unit 31 acquires image data from the image pickup device 3. Image data is roughly classified into two types. One is the image data generated by imaging the side end 83 of the measurement work 80, that is, the measurement work image 89 (see FIG. 10). The other is image data generated by imaging the reference surface 93 of the reference work 90, that is, the reference work image 99 (see FIG. 8). The reference work 90 will be described later with reference to FIGS. 6 to 9.

The coefficient calculation unit 32 calculates the conversion coefficient K with reference to the reference work image 99. The conversion coefficient K is expressed in units of, for example, "millimeters per pixel" (pix / mm), and can be said to be the reciprocal of the pixel resolution (mm / pix). In other words, the conversion coefficient K is the amount of pixels (pix) on the image data corresponding to the unit distance (mm) in the spatial coordinate system CS1.
When image data is generated by imaging a subject using the imaging device 3, the conversion coefficient K (pix / mm) is calculated as the distance (mm) measured in the spatial coordinate system CS1 in relation to the subject. To be multiplied. As a result, the distance is converted into a pixel amount (pix) on the image data. The calculation method of the conversion coefficient K will be described later with reference to FIGS. 8 and 9.

The reference coordinate measuring unit 33 measures the reference coordinate value with reference to the reference work image 99. The reference coordinate value is a pixel position on the image data corresponding to a predetermined reference position (that is, a predetermined reference position set in the work space) defined in the spatial coordinate system CS1. The reference coordinate value is defined in the image coordinate system CS2. In the present embodiment, two reference positions, the front side reference position RP1 and the back side reference position RP2, are set in the work space (see FIG. 9). The reference coordinate measuring unit 33 measures two reference coordinate values, a front reference coordinate value RP1p corresponding to the front reference position RP1 and a back reference coordinate value RP2p corresponding to the back reference position RP2, as reference coordinate values. The method of measuring the reference coordinate value will be described later with reference to FIGS. 8 and 9.

The displacement information acquisition unit 34 acquires surface displacement information from the first displacement sensor 4. The displacement information acquisition unit 34 acquires backside displacement information from the second displacement sensor 5. The surface displacement information indicates the distance ΔZ1 from the front side reference position RP1 to the surface 81 of the measuring work 80 in the normal direction (vertical direction (Z direction)) of the surface 81 of the measuring work 80. The back surface displacement information indicates the distance ΔZ2 from the back side reference position RP2 to the back surface 82 of the measurement work 80 in the normal direction (vertical direction (Z direction)) of the back surface 82 of the measurement work 80. The method for measuring the distances ΔZ1 and ΔZ2 will be described later with reference to FIG.

The measurement surface calculation unit 35 calculates the surface coordinate value y81 representing the position of the surface 81 of the measurement work 80 on the measurement work image 89 based on the conversion coefficient K, the distance ΔZ1 indicated by the surface displacement information, and the front side reference coordinate value RP1p. calculate. The measurement surface calculation unit 35 calculates the back surface coordinate value y82 indicating the position of the back surface 82 of the measurement work 80 on the measurement work image 89 based on the conversion coefficient K, the distance ΔZ2 indicated by the back surface displacement information, and the back surface reference coordinate value RP2p. calculate. The method of calculating the coordinate values will be described later with reference to FIGS. 10 and 11.
The image processing unit 36 measures the shape of the side end portions 83 (bevel portions 84a, 84b) on the measurement work image 89 in consideration of the measurement result of the position by the measurement surface calculation unit 35. The shape measurement will be described later with reference to FIG.

(Shape measurement method)
Hereinafter, the operation of the shape measuring device 10 will be described with reference to FIGS. 6 to 12 according to the procedure of the shape measuring method according to the present embodiment shown in FIG. The process shown in FIG. 5 ends when the shape of the side end portion 83 of one measuring work 80 is measured. The process shown in FIG. 5 is repeatedly executed in order to measure the side end portions 83 of the plurality of measuring workpieces 80.

First, the worker or the shape measuring device 10 determines the necessity of calibration (S1). This "calibration" includes calibration of the reference value (zero value) set in the first displacement sensor 4 and the second displacement sensor 5, and calibration of the conversion coefficient K and the reference coordinate value stored in the storage unit 20. Is done. Further, calibration of the positions and orientations of the lighting device 2, the imaging device 3, the first displacement sensor 4 and the second displacement sensor 5 may be included.

Whether or not calibration is necessary is determined in light of the success or failure of a plurality of conditions such as the temperature in the work space and the number of continuous measurements of the shape of the measuring work 80. When the temperature changes, the distance measurement value may fluctuate due to the influence of the temperature characteristics of the first displacement sensor 4 and the second displacement sensor 5 and the expansion and contraction of the sensor support jig 16. Therefore, when the temperature changes beyond a predetermined value, calibration may be performed in order to maintain the measurement accuracy. Further, calibration may be performed every time the shape of the specified number of measuring works 80 is continuously measured, or every time the shape of the measuring work 80 is continuously measured for a specified time.

If calibration is required (S1: Y), the reference work 90 is installed on the work support device 11 instead of the measurement work 80 (S11). This installation may be automatically performed by a work transfer robot (not shown). When the reference work 90 is installed on the work support device 11, the posture control unit 24 controls the posture of the reference work 90 (S12). In order to realize the attitude control of the reference work 90 by the attitude control device 13, the reference work 90 is also provided with an orientation indicator (not shown) detected by the work position sensor 12 as in the measurement work 80. ..

(Reference work)
FIG. 13 shows a reference work 90. 6 and 7 show the shape measurement system 1 after the attitude control of the reference work 90. The reference work 90 is formed in a plate shape. The reference work 90 has a front surface 91 and a back surface 92. The front surface 91 and the back surface 92 are parallel to each other, so that the plate thickness of the reference work 90 is uniform.

The reference work 90 has a reference surface 93. The reference surface 93 makes it possible to identify the contour of the reference work 90 on the reference work image 99 captured by the imaging device 3. In the present embodiment, the reference surface 93 connects the front surface 91 and the back surface 92 in the plate thickness direction of the reference work 90. Therefore, on the reference work image 99, the contour of the reference work 90 is formed by the front surface 91 and the back surface 92. The reference surface 93 is flat. Further, the reference surface 93 is perpendicular to the front surface 91 and the back surface 92.

The shape of the reference work 90 in a plan view is not particularly limited. The reference work 90 may be formed in a semicircular shape, for example, by cutting a circle having the same diameter as the measuring work 80 on the diameter in a plan view. This cut surface is suitably used as a reference surface 93.
As a result of the attitude control in step S12, the focus of the image pickup apparatus 3 is positioned on the reference plane 93. Furthermore, the reference plane 93 overlaps with the focal plane FP. Therefore, in the present embodiment, the reference work 90 is placed on a half of the rotary table 11a.

The measuring work 80 as a glass wafer is manufactured of glass in order to meet the demand as a product, and these materials have high light transmission or high light scattering property. When such a measurement work 80 is imaged, the image is easily blurred. On the other hand, since the reference work 90 is a work dedicated to imaging, it is allowed to be manufactured of a material having a lower light transmittance or a lower light scattering property than the measurement work 80. As a result, an image with less blurring can be obtained as compared with the case where the measurement work 80 is imaged. The reference work 90 may be made of synthetic resin or metal.

(Acquisition of reference work image)
Next, the imaging device 3 images the reference work 90 (S13). Comparing FIGS. 6 and 7 with FIGS. 1 and 2, the lighting device 2 and the imaging device 3 are arranged in the work space at the same positions and postures as when the measurement work 80 is imaged. The focal plane FP forms a YZ plane in the spatial coordinate system CS1. The reference surface 93 of the reference work 90 is overlapped on the focal surface FP as a result of the attitude control in step S12. While the illumination device 2 is irradiating the illumination light, the image pickup apparatus 3 is controlled by the camera control unit 22, and the reference surface 93 of the reference work 90 is controlled from a direction (X direction) orthogonal to the reference surface 93 of the reference work 90. To image.

Next, the image acquisition unit 31 acquires the reference work image 99 from the image pickup apparatus 3 (S14). With reference to FIG. 8, on the reference work image 99, the images of the front surface 91 and the back surface 92 of the reference work 90 are clear. This is because the material of the reference work 90 is taken into consideration as described above. Further, the reference plane 93 faces the image pickup apparatus 3 in a state of being overlapped on the focal plane FP. The reference work 90 has no front surface 91 and no back surface 92 on the image pickup apparatus 3 side of the focal plane FP. That is, the depths of the front surface 91 and the back surface 92 with respect to the focal plane FP are smaller than the depth of the measuring work 80. Therefore, the entire reference surface 93 is in focus, and a clear image of the front surface 91 and the back surface 92 can be obtained.

(Calculation of conversion coefficient)
Next, the coefficient calculation unit 32 calculates the conversion coefficient K (S15). With reference to FIGS. 8 and 9, the plate thickness of the reference work 90 has already been measured before the shape measuring method is started. Since the reference work 90 is supported by the work support device 11, the plate thickness direction of the reference work 90 is directed to the vertical direction (Z direction). Further, the plate thickness of the reference work 90 is uniform.

First, the coefficient calculation unit 32 refers to the reference work image 99 and calculates the reference dimension pixel amount t90p corresponding to the measured value t90 of the plate thickness of the reference work 90 in the image coordinate system CS2. The vertical axis y direction of the image coordinate system CS2 corresponds to the vertical direction (Z direction), that is, the plate thickness direction of the reference work 90. The image of the front surface 91 and the image of the back surface 92 extend linearly in the horizontal axis x direction of the image coordinate system CS2.

The coefficient calculation unit 32 specifies the position of the surface 91 on the image. The surface 91 is imaged with pixels at substantially the same position in the vertical axis y direction regardless of the position in the horizontal axis x direction. The coefficient calculation unit 32 calculates the reference surface coordinate value y91 representing the position in the vertical axis y direction of the pixel on which the surface 91 is formed on the image with reference to the measurement work image 89. In the calculation of the reference surface coordinate value y91, for example, the y coordinate values of the imaging pixels arranged in the horizontal axis x direction may be averaged. When identifying the imaged pixels, the image may be sharpened by the differentiation process and / or the binarization process of the gradation value of each pixel.

In the same manner as this, the coefficient calculation unit 32 calculates the reference back surface coordinate value y92 representing the position in the vertical axis y direction of the pixel on which the back surface 92 is formed on the image with reference to the reference work image 99.
Next, the coefficient calculation unit 32 calculates the reference dimension pixel amount t90p based on the reference front surface coordinate value y91 and the reference back surface coordinate value y92. The reference dimension pixel amount t90p is an absolute value of the difference between the reference front surface coordinate value y91 and the reference back surface coordinate value y92.

Next, the coefficient calculation unit 32 calculates the conversion coefficient K based on the reference dimension pixel amount t90p and the actually measured value t90. The conversion coefficient K is calculated by dividing the reference dimension pixel amount t90p by the actually measured value t90. For example, if the measured value t90 is 5 mm and the reference dimension pixel amount t90p is 200 pix, the conversion coefficient K is 40 pix / mm. With this conversion coefficient K, it is possible to convert the distance in the vertical direction (Z direction) in the work space into the amount of pixels in the vertical axis y direction of the image coordinate system CS2.

(Measurement of reference coordinate value)
Next, the reference coordinate measuring unit 33 measures the front side reference coordinate value RP1p and the back side reference coordinate value RP2p as the reference coordinate values (S16). In the present embodiment, the front side reference position RP1 set in the spatial coordinate system CS1 is set on the surface 91 of the reference work 90. The back side reference position RP2 set in the spatial coordinate system CS1 is set on the back side 92 of the reference work 90.

The front reference position RP1 corresponds to the reference surface coordinate value y91 calculated by the coefficient calculation unit 32 on the reference work image 99. The back side reference position RP2 corresponds to the reference back side coordinate value y92 calculated by the coefficient calculation unit 32 on the reference work image 99. Therefore, the reference coordinate measuring unit 33 sets the reference surface coordinate value y91 as the front side reference coordinate value RP1p, and sets the reference back surface coordinate value y92 as the back side reference coordinate value RP2p. Since the calculated coordinate value is diverted as the reference coordinate value, the process is simplified.
Next, the conversion coefficient K and the reference coordinate values RP1p and RP2p are stored in the storage unit 20 (S17). The stored value is used in the subsequent measurement of the shape of the measuring work 80.

(Zero reset)
Next, the zero reset process for the first displacement sensor 4 and the second displacement sensor 5 is executed (S18). The first displacement sensor 4 and the second displacement sensor 5 are not required in the calculation process of the conversion coefficient K (S15) and the measurement process of the reference coordinate values RP1p and RP2p (S16). The first displacement sensor 4 and the second displacement sensor 5 may or may not be arranged in the work space at the time of executing these processes S15 and S16. When the zero reset process (S18) is executed, the first displacement sensor 4 and the second displacement sensor 5 are supported by the sensor support jig 16.

With reference to FIGS. 6, 7 and 9, the first displacement sensor 4 measures the distance from itself to the surface 91 of the reference work 90 in the plate thickness direction of the reference work 90, that is, the vertical direction (Z direction). do. The position Z91 of the surface 91 in the vertical direction (Z direction) is the front side reference position RP1. The front side reference position RP1 reflecting the measurement medium from the first displacement sensor 4 is set to the reference value (zero value) of the first displacement sensor 4.

The means for setting the reference value is not particularly limited. For example, a process of setting a reference value by pressing a switch attached to the housing of the first displacement sensor 4 may be automatically performed inside the first displacement sensor 4.
The same applies to the second displacement sensor 5. The second displacement sensor 5 measures the distance from itself to the back surface 92 of the reference work 90 in the plate thickness direction of the reference work 90, that is, the vertical direction (Z direction). The position Z92 of the back surface 92 in the vertical direction (Z direction) is the back side reference position RP2. This back side reference position RP2 is set to the reference value (zero value) of the second displacement sensor 5.

This completes the calibration using the reference work 90. Subsequently, the shape of the side end portion 83 of the measuring work 80 is measured, and the positions, orientations, and settings of the lighting device 2, the imaging device 3, the first displacement sensor 4, and the second displacement sensor 5 are calibrated. It is maintained in the same state. The maintained "setting" includes, for example, the setting of the magnification (optical magnification) of the image pickup device 3 and the setting of the focal length (position of the focal plane FP in the optical axis direction) of the image pickup device 3.

(Installation of measurement work)
After the calibration is completed or when the calibration is not required (S1: N), the measuring work 80 is supported by the work support device 11 (S21). Next, the posture control unit 24 controls the posture of the measurement work 80 (S22). As a result of the attitude control, the measurement work 80 stands still in a posture in which, for example, the orientation indicating unit is out of the field of view of the image pickup apparatus 3.

(Measurement work image acquisition)
Next, the imaging device 3 images the measurement work 80 (S23). With reference to FIGS. 1 and 2, the image pickup device 3 is controlled by the camera control unit 22 in a state where the lighting device 2 is irradiating the illumination light, and is controlled in one direction (space) parallel to the surface 91 of the measurement work 80. The side end 83 of the measurement work 80 is imaged from the X direction in the coordinate system CS1).
Next, the image acquisition unit 31 acquires the measurement work image 89 from the image pickup apparatus 3 (S24). With reference to FIG. 10, in the measurement work image 89, as described above, both the image of the front surface 81 and the image of the back surface 82 are blurred due to the influence of the material and depth of the measurement work 80.

(Displacement information acquisition)
Next, the first displacement sensor 4 measures the distance ΔZ1 from the front side reference position RP1 to the surface 81 of the measuring work 80 in the plate thickness direction of the measuring work 80, that is, the vertical direction (Z direction) (S25). In the first displacement sensor 4, the front side reference position RP1 is set as a reference value (zero value). The first displacement sensor 4 measures the distance from itself to the surface 81, and detects the distance ΔZ1 (displacement amount) of the surface 81 from the reference value based on the measurement result. The first displacement sensor 4 outputs the detected distance ΔZ1 as a distance measurement value to the shape measuring device 10.

Further, the second displacement sensor 5 measures the distance ΔZ2 from the back side reference position RP2 to the back surface 82 of the measuring work 80 in the plate thickness direction of the measuring work 80, that is, the vertical direction (Z direction) (S25). The second displacement sensor 5 outputs the distance ΔZ2 as a distance measurement value to the shape measuring device 10.
With reference to FIG. 11, both the back surface 82 of the measuring work 80 and the back surface 92 of the reference work 90 are placed on the upper surface of the rotary table 11a of the work support device 11. Therefore, in the plate thickness direction (Z direction) of the measuring work 80, the position Z82 of the back surface 82 of the measuring work 80 is substantially the same as the back side reference position RP2. However, in reality, the measuring work 80 is slightly warped. Further, when the rotary table 11a is rotated, a slight inclination or tilt occurs. Therefore, the distance ΔZ2 may change.

On the other hand, in the plate thickness direction (Z direction) of the measuring work 80, the position Z81 of the surface 81 of the measuring work 80 is the front side reference position RP1 according to the difference between the plate thickness of the measuring work 80 and the plate thickness of the reference work 90. Changes from. The amount of displacement from the front reference position RP1 is the distance ΔZ1.
Next, the displacement information acquisition unit 34 acquires the front surface displacement information from the first displacement sensor 4 and the back surface displacement information from the second displacement sensor 5 (S26). The surface displacement information indicates the distance ΔZ1. The back surface displacement information indicates the distance ΔZ2.

(Calculation of front coordinate value and back surface coordinate value)
Next, the measurement surface calculation unit 35 converts the distance ΔZ1 indicated by the surface displacement information into the surface displacement pixel amount Δy1 using the conversion coefficient K stored in the storage unit 20 (S27). Further, the measurement surface calculation unit 35 converts the distance ΔZ2 indicated by the back surface displacement information into the back surface displacement pixel amount Δy2 using the conversion coefficient K (S27). As described above, by multiplying the distance by the conversion coefficient K, the distance in the spatial coordinate system CS1 is converted into the pixel amount in the image coordinate system CS2.

Next, the measurement surface calculation unit 35 corrects the front side reference coordinate value RP1p with the surface displacement pixel amount Δy1 to calculate the surface coordinate value y81 indicating the position of the surface 81 of the measurement work 80 on the measurement work image 89. (S28). Further, the measurement surface calculation unit 35 corrects the front side reference coordinate value RP1p with the surface displacement pixel amount Δy1 to calculate the back surface coordinate value y82 indicating the position of the back surface 82 of the measurement work 80 on the measurement work image 89. ..

With reference to FIGS. 10 and 11, since the position, posture, and setting of the image pickup apparatus 3 are not changed between the time of imaging the reference work 90 and the time of imaging of the measurement work 80, the measurement work 80 is also imaged. The front side reference coordinate value RP1p corresponds to the front side reference position RP1 in the spatial coordinate system CS1 as in the case of imaging of the reference work 90. When the surface 81 of the measuring work 80 is separated from the front reference position RP1 by the distance ΔZ1, the surface 81 is separated from the front reference coordinate value RP1p by the surface displacement pixel amount Δy1 on the measurement work image 89.

Therefore, the measurement surface calculation unit 35 calculates the surface coordinate value y81 by adding the surface displacement pixel amount Δy1 to the front side reference coordinate value RP1p. The distance ΔZ1 can be either a positive value or a negative value depending on whether the displacement is upward or downward with respect to the front reference position RP1. Therefore, the surface displacement pixel amount Δy1 also becomes a positive value or a negative value depending on the displacement direction of the surface 81. "Addition" means that the surface coordinate value y81 is increased and corrected with respect to the front reference coordinate value RP1p by adding the positive value, and the surface coordinate value y81 is corrected with respect to the front reference coordinate value RP1p by adding the negative value. Including both being done.

The same applies to the back surface coordinate value y82. The measurement surface calculation unit 35 calculates the back surface coordinate value y82 by adding the back surface displacement pixel amount Δy2 to the back side reference coordinate value RP2p. The backside displacement pixel amount Δy2 is the product of the distance ΔZ2 and the conversion coefficient K.
Although detailed illustration is omitted, when the distance ΔZ2 is a zero value, the backside displacement pixel amount Δy2 as a correction amount for correcting the backside reference coordinate value RP2p also becomes a zero value. The back side coordinate value y82 is not substantially corrected from the back side reference coordinate value RP2p, and the measurement surface calculation unit 35 sets the back side reference coordinate value RP2p as the back side coordinate value y82.

(Measurement of the shape of the side end)
Next, the image processing unit 36 measures the shape of the side end portions 83 of the measurement work 80, particularly the bevel portions 84a and 84b, on the measurement work image 89 (S29). In the original measurement work image 89 (see FIG. 10) acquired from the image pickup apparatus 3, the images of the front surface 81 and the back surface 82 were blurred, but by the above processing, the front surface 81 and the back surface 82 on the measurement work image 89 Positions y81 and y82 have already been specified.

FIG. 12 shows an example of the side end measurement image 89A created by the image processing unit 36 based on this specific result. In the side end measurement image 89A according to the present embodiment, virtual straight lines 81A and 82A extending in the horizontal axis x direction are drawn on the positions y81 and y82 calculated by the measurement surface calculation unit 35. The virtual straight line 81A represents the front surface 81, and the virtual straight line 82A represents the back surface 82 (see also FIG. 3). The image processing unit 36 can clearly recognize the positions of the front surface 81 and the back surface 82 in this way.

Even on the original measurement work image 89, the image of the side edge edge is clear. The image processing unit 36 may draw a virtual straight line 87A that passes through the side edge and extends in the vertical axis y direction. The virtual straight line 87A represents the side surface 87 (see FIG. 3) of the measuring work 80 that existed before the chamfering process. The portions surrounded by the virtual straight lines 81A, 82A, 87A and the contour images of the bevel portions 84a, 84b are the portions cut off from the measuring work 80 by chamfering.

The image processing unit 36 can measure the shape of the front side bevel portion 84a based on the side end portion measurement image 89A. The image processing unit 36 can measure the shape of the back side bevel portion 84b based on the side end portion measurement image 89A. However, this side end measurement image 89A is an example, and a blurred image in a region deviating from the virtual straight lines 81A and 82A may be erased.

(Action effect)
In the present embodiment, a so-called light projection measurement method is used to measure the shape of the side end portion 83 of the plate-shaped measuring work 80 having the front surface 81 and the back surface 82. However, the measurement surface calculation unit 35 does not adopt a method of specifying the contour of the blurred surface 81 on the measurement work image 89 and estimating the position of the surface 81 from the specified contour.

In the image coordinate system CS2 defined on the image, the reference coordinate value RP1p corresponding to the predetermined reference position RP1 is measured in advance. A conversion coefficient K (pix / mm) representing the amount of pixels in the image coordinate system CS2 corresponding to the unit distance is calculated in advance. Then, instead of specifying the contour on the measurement work image 89, the distance ΔZ1 from the reference position RP1 to the surface 81 of the measurement work 80 is measured. This distance ΔZ1 is converted into the pixel amount (surface displacement pixel amount Δy1) in the image coordinate system CS2 using the conversion coefficient K. In the space where the measuring work 80 is installed, when the surface 81 of the measuring work 80 is separated from the reference position RP1 by the measured distance (mm), the surface 81 is on the measuring work image 89 from the reference coordinate value RP1p. The surface displacement pixels are separated by Δy1 (pix). The measurement surface calculation unit 35 calculates the surface coordinate value y81 by correcting the reference coordinate value RP1p with the surface displacement pixel amount Δy1.

In this way, the position of the surface 81 is specified by using the surface displacement pixel amount Δy1 converted from the measurement result of the distance ΔZ1. The position of the surface 81 can be measured more accurately and easily than in the case of estimating the position of the surface 81 from the blurred measurement work image 89.
The coefficient calculation unit 32 calculates the conversion coefficient K with reference to the reference work image 99. In the reference work image 99, the reference surface 93 of the reference work 90 is projected. The coefficient calculation unit 32 calculates a reference dimension pixel amount t90p corresponding to a predetermined dimension (for example, plate thickness) of the reference work 90 in the image coordinate system CS2 defined on the image based on the contour of the reference surface 93. The predetermined dimensions of the reference work 90 have already been measured (known). The conversion coefficient K is calculated from the reference dimension pixel amount t90p and the actually measured value t90 of the predetermined dimension.

The reference coordinate measuring unit 33 measures the reference coordinate value RP1p with reference to the reference work image 99. The reference coordinate value RP1p is a coordinate value in the image coordinate system CS2 corresponding to the reference position RP1 set in the space where the reference work 90 or the measurement work 80 is installed. The reference position RP1 is set on the reference work 90. The reference coordinate measuring unit 33 measures the reference coordinate value RP1p based on the image of the reference work 90 projected on the reference work image 99.

In this way, by referring to the reference work image 99, the conversion coefficient K and the reference coordinate value RP1p can be obtained before measuring the position of the surface 81 of the measurement work 80. The above-mentioned calculation method of the surface coordinate value y81 can be realized.
When the reference work 90 is imaged, the reference work 90 does not exist on the image pickup device 3 side of the reference surface 93 of the reference work 90. Therefore, the reference work image 99 is less likely to be blurred than the measurement work image 89. Since the reference work image 99 with suppressed blurring is referred to, the calculation accuracy of the reference dimension pixel amount t90p and the conversion coefficient K is improved. The measurement accuracy of the reference coordinate value RP1p corresponding to the reference position RP1 is improved. Since these accuracy is high, the calculation accuracy of the surface coordinate value y81 by the measurement surface calculation unit 35 is high. The measuring work 80 is made of a transparent material such as glass, and even if the measuring work image 89 is easily blurred, the position of the surface 81 can be measured accurately.

The above is related to the measurement of the position of the surface 81. In the present embodiment, the same process as the measurement of the position of the surface 81 is performed by using the second displacement sensor 5. Therefore, the position of the back surface 82 on the measurement work image 89 can also be measured with high accuracy.

(Modification example)
Although embodiments of the present invention have been described above, the above configurations and methods can be appropriately modified, deleted and / or added within the scope of the present invention.
In the above embodiment, the reference surface 93 of the reference work 90 connects the front surface 91 and the back surface 92 in the plate thickness direction, and the contour of the reference surface 93 is formed by the front surface 91 and the back surface 92. The conversion coefficient K is calculated based on the measured value of the plate thickness and the amount of pixels corresponding to the plate thickness in the image coordinate system CS2. However, the reference surface 93 is not limited to such an aspect. Therefore, the conversion coefficient K may be calculated using a predetermined dimension in the reference work 90 other than the plate thickness.

In the above embodiment, the positions of both the front surface 81 and the back surface 82 were measured because the chamfering process is performed on both the front side and the back side. If the chamfering process is performed only on the front side, the shape measuring system 1 may measure only the position of the surface 81. When the surface 81 is directed upward and supported by the work support device 11, the second displacement sensor 5 is omitted. When the surface 81 is directed downward and supported by the work support device 11, the upper first displacement sensor 4 is omitted, and the lower second displacement sensor 5 functions as the first displacement sensor 4.

The front side reference position RP1 and the back side reference position RP2 may be set on the reference work 90, and may be set at a place other than the front surface 91 and the back surface 92. Further, the reference position may be common to the front side and the back side.
Even when the measuring work 80 is not chamfered, the shape measuring system 1 can accurately measure the shape of the side end portion 83 of the measuring work 80. The measuring work 80 is not limited to a wafer, and may be another plate-shaped work such as a substrate for a liquid crystal display.

1 Shape measurement system 3 Imaging device 4 1st displacement sensor 5 2nd displacement sensor 10 Shape measurement device 31 Image acquisition unit 32 Coefficient calculation unit 33 Reference coordinate measurement unit 34 Displacement information acquisition unit 35 Measurement surface calculation unit 36 Image processing unit 80 Measurement Work 81 Front side 82 Back side 83 Side end 84a, 84b Bevel part 89 Measurement work image 90 Reference work 91 Front side 92 Back side 93 Reference surface 99 Reference work image CS2 Image coordinate system FP Focus plane K Conversion coefficient RP1 Front side reference position (reference position)
RP2 back side reference position (reference position)
RP1p front side reference coordinate value (reference coordinate value)
RP2p back side reference coordinate value (reference coordinate value)
t90 measured value t90p reference dimension pixel amount y81 front surface coordinate value y82 back surface coordinate value y91 reference front surface coordinate value y92 reference back surface coordinate value Z81 front surface position of measurement work Z82 back surface position of measurement work ΔZ1, ΔZ2 distance

Claims (16)

A shape measuring device that measures the shape of the side end of a plate-shaped measuring work having a front surface and a back surface.
The reference work image generated by imaging the reference plane of the reference work using the image pickup device is acquired from the image pickup device, and the image pickup device is used from one direction substantially parallel to the surface of the measurement work. An image acquisition unit that acquires a measurement work image generated by imaging the side end portion of the measurement work from the image pickup apparatus, and an image acquisition unit.
Based on the reference plane on the reference work image, the reference dimension pixel amount corresponding to the predetermined dimension of the reference work is calculated in the image coordinate system defined on the image, and the measured value of the predetermined dimension is used. A coefficient calculation unit that calculates a conversion coefficient representing a pixel amount corresponding to a unit distance based on the reference dimension pixel amount.
With reference to the reference work image, a reference coordinate measuring unit for measuring a reference coordinate value in the image coordinate system corresponding to a predetermined reference position set on the reference work, and a reference coordinate measuring unit.
A displacement information acquisition unit that acquires surface displacement information indicating the distance from the reference position to the surface of the measurement work in the plate thickness direction of the measurement work.
By converting the distance indicated by the surface displacement information into a surface displacement pixel amount using the conversion coefficient and correcting the reference coordinate value with the surface displacement pixel amount, the measurement work image is described. A measurement surface calculation unit that calculates surface coordinate values representing the position of the surface of the measurement work,
A shape measuring device. The reference work has the reference surface capable of identifying the contour of the reference work on the reference work image captured by the imaging device.
The shape measuring device according to claim 1. The reference work is made of a material having a lower light transmittance than the measurement work.
The shape measuring device according to claim 1 or 2. The reference work is formed in a plate shape having a front surface and a back surface, and has a uniform plate thickness.
The reference surface connects the front surface and the back surface in the plate thickness direction of the reference work, and the contour of the reference surface is formed by the front surface and the back surface.
The predetermined dimension of the reference work is the plate thickness of the reference work.
The shape measuring device according to any one of claims 1 to 3. The coefficient calculation unit
A reference surface coordinate value representing the position of the front surface of the reference work and a reference back surface coordinate value representing the position of the back surface of the reference work are calculated on the reference work image, and
The reference dimension pixel amount is calculated based on the reference front surface coordinate value and the reference back surface coordinate value.
The shape measuring device according to claim 4. The reference position is set on the front surface or the back surface of the reference work in a state where the reference work is imaged by using the imaging device.
The reference coordinate measuring unit determines the reference front surface coordinate value or the reference back surface coordinate value as the reference coordinate value.
The shape measuring device according to claim 5. The displacement information acquisition unit acquires back surface displacement information indicating the distance from the reference position to the back surface of the measurement work in the plate thickness direction of the measurement work.
The measurement surface calculation unit converts the distance indicated by the back surface displacement information into a back surface displacement pixel amount using the conversion coefficient, and corrects the reference coordinate value with the back surface displacement pixel amount. Calculate the back surface coordinate value representing the position of the back surface of the measurement work on the measurement work image.
The shape measuring device according to any one of claims 1 to 6. An image processing unit for measuring the shape of the bevel portion provided at the side end portion on the measurement work image based on the surface coordinate values is further provided.
The shape measuring device according to any one of claims 1 to 7. The shape measuring device according to any one of claims 1 to 8.
An imaging device that images the measurement work to generate the measurement work image, and images the reference work to generate the reference work image.
A first displacement sensor that measures the distance from the predetermined reference position to the surface of the measuring work in the plate thickness direction of the measuring work and outputs the surface displacement information.
A shape measurement system. The focus of the imaging device is located on the reference plane of the reference work.
The shape measuring system according to claim 9. The imaging device images the reference work from a direction substantially orthogonal to the reference plane of the reference work, and the reference plane is superposed on the focal plane of the imaging device.
The shape measuring system according to claim 10. The position, posture, and magnification of the imaging device are set to be the same when the reference work is imaged and when the measurement work is imaged.
The shape measuring system according to any one of claims 9 to 11. In a state where the reference work is imaged, the first displacement sensor is calibrated so that the distance measurement value becomes a zero value at the reference position on the reference work.
The shape measuring system according to any one of claims 9 to 12. A second displacement sensor that measures the distance from the reference position to the back surface of the measuring work in the plate thickness direction of the measuring work and outputs backside displacement information indicating the measurement result is further provided.
The measurement surface calculation unit converts the distance indicated by the back surface displacement information into a back surface displacement pixel amount using the conversion coefficient, and corrects the reference coordinate value with the back surface displacement pixel amount. Calculate the back surface coordinate value representing the position of the back surface of the measurement work on the measurement work image.
The shape measuring system according to any one of claims 9 to 13. A shape measuring method for measuring the shape of the side end of a plate-shaped measuring work having a front surface and a back surface.
A reference work image acquisition step of acquiring a reference work image generated by imaging a reference plane of a reference work using an imaging device from the imaging device, and
Based on the reference plane on the reference work image, the reference dimension pixel amount corresponding to the predetermined dimension of the reference work is calculated in the image coordinate system defined on the image, and the measured value of the predetermined dimension is used. A coefficient calculation step of calculating a conversion coefficient representing a pixel amount corresponding to a unit distance based on the reference dimension pixel amount.
A reference coordinate measuring step of measuring a reference coordinate value in the image coordinate system corresponding to a predetermined reference position set on the reference work with reference to the reference work image, and
A measurement work image acquisition step of acquiring a measurement work image generated by imaging the side end portion of the measurement work from the image pickup device from one direction parallel to the surface of the measurement work. ,
A displacement information acquisition step of acquiring surface displacement information indicating a distance from the reference position to the surface of the measurement work in the normal direction of the surface of the measurement work.
By converting the distance indicated by the surface displacement information into a surface displacement pixel amount using the conversion coefficient and correcting the reference coordinate value with the surface displacement pixel amount, the measurement work image is described. A measurement surface calculation step for calculating surface coordinate values representing the position of the surface of the measurement work, and
A shape measuring method. A shape measurement program that causes a computer to execute the shape measurement method according to claim 15.

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