JP2012007961A - Shape measuring apparatus and shape measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measuring apparatus capable of improving measurement accuracy of uneven shapes.SOLUTION: The shape measuring apparatus of the present invention comprises: a light projector 2 for projecting line light to uneven shapes of a measurement object 1; an imaging device 3 for imaging a light cutting line that is formed on the uneven shapes by the light projector 2; a driving device 5 for moving the light projector 2 in a light-outgoing axis direction 4 so that the width of the light cutting line becomes a minimum in each of upper bases and lower bases of the uneven shapes; a processor 6 for calculating the height or depth of the uneven shapes based on an image that is imaged by the imaging device 3 and in which the width of the light cutting line becomes a minimum on the upper bases of the uneven shapes and an image that is imaged by the imaging device 3 and in which the width of the light cutting line becomes a minimum on the lower bases of the uneven shapes.

Description

  The present invention relates to a shape measuring apparatus and a shape measuring method for measuring the height or depth of an uneven shape to be measured.

  A conventional shape measuring apparatus that measures the height or depth of a concavo-convex shape to be measured is described in Patent Document 1, for example. As shown in FIG. 15, the shape measuring apparatus described in Patent Document 1 includes two projection apparatuses 103 a that irradiate an inspection object 102 fixed on an inspection stage 101 with a linear laser beam, 103b, one imaging device 105 on which the scattered light from the object 102 is imaged on the imaging surface via the lens 104, and a process for calculating the height or depth of the irregularities on the surface of the object 102 A device 106 is provided.

  Specifically, the two projectors 103a and 103b irradiate the surface of the inspection object 102 with line-shaped laser light from different directions. The imaging device 105 images two laser light cutting lines formed on the surface of the inspection object 102 by the line-shaped laser beams from the two projection devices 103a and 103b. The processing device 106 extracts the laser beam cutting line from the image captured by the imaging device 105, and then extracts a portion corresponding to the extracted laser beam cutting line from the reference image acquired in advance. The laser beam cutting line extracted from the image picked up by the above is compared with the portion extracted from the reference image, and position information in the height direction of the laser beam cutting line is detected based on the comparison result.

  The conventional shape measuring apparatus inspects the height or depth of the unevenness of the entire surface of the inspection object 102 by repeating the above operation by moving the inspection stage 101 by a certain step width.

  The reference image is acquired by scanning the surface of a metal member having the same shape as the object to be inspected 102 and having no irregularities on the surface with linear laser beams from the two projectors 103a and 103b. Therefore, the laser beam cutting line extracted from the reference image is a straight line.

  As described above, the conventional shape measuring apparatus irradiates the measurement target with line-shaped laser light from a plurality of different directions, thereby reducing the blind spot and improving the measurement accuracy.

JP 2005-337856 A

  However, since the conventional shape measuring apparatus requires a plurality of projection apparatuses, the cost increases. Further, the measurement target is irradiated with a line-shaped laser beam, and a light cutting line formed on the surface of the measurement target is imaged. The height or depth of the unevenness on the surface of the measurement target based on the captured image. , The center of the optical cutting line in the vertical width direction (direction orthogonal to the longitudinal direction of the optical cutting line) is calculated, and the calculated center of the optical cutting line is regarded as an image of the measurement site. However, since the laser light applied to the measurement object is parallel light such as slit light, the vertical width of the light cutting line is a certain level or more. As a result, an error is likely to occur when calculating the center in the vertical width direction of the light section line, and the measurement accuracy is insufficient. As a method of narrowing the vertical width of the light cutting line, a method of condensing the laser light irradiated to the measurement object can be considered. However, when optically cutting a measurement object having a concavo-convex shape, laser light cannot be condensed simultaneously on the upper and lower bases of the concavo-convex shape, so either one of the optical cutting lines at the upper and lower bases. Has a certain vertical width. Furthermore, since the laser beam cannot be focused simultaneously on the upper and lower bases of the concavo-convex shape, the center of gravity position in the vertical width direction of the luminance value of the light cutting line is determined by the laser beam focusing point and its focusing point. It changes between other places. As described above, the position of the center of gravity in the vertical width direction of the luminance value of the light section line varies depending on the location, which causes an error. This is because when calculating the center in the vertical width direction of the light cutting line, an area having a luminance value equal to or higher than a predetermined threshold is extracted from the image obtained by capturing the light cutting line, and the vertical width of the extracted area is calculated as the light width. This is because it is regarded as the vertical width of the cutting line and the center of the vertical width is calculated.

  As described above, in the conventional shape measuring apparatus, the optical cutting line has a certain vertical width or more depending on the location, and the center of gravity position in the vertical width direction of the luminance value of the optical cutting line varies depending on the location. When calculating the center in the vertical width direction, an error is likely to occur, resulting in insufficient measurement accuracy.

  In view of the above problems, the present invention suppresses measurement errors caused by fluctuations in the vertical width of the light cutting line and the luminance value of the light cutting line, and can improve the measurement accuracy of the uneven shape. An object is to provide a measuring apparatus and a shape measuring method.

  In order to achieve the above object, a shape measuring device of the present invention images a light projecting device that irradiates line light onto a concavo-convex shape to be measured, and a light cutting line formed in the concavo-convex shape by the light projecting device. An imaging device, a driving device for moving the light projecting device in the direction of the light emission axis so that the vertical width of the light cutting line is minimized at each of the upper and lower bases of the concavo-convex shape, and the imaging device Based on the imaged image in which the vertical width of the optical cutting line is minimized at the upper base of the concave-convex shape, and the concave-convex shape based on the image in which the vertical width of the optical cutting line is minimum at the lower base of the concave-convex shape And a processing device for calculating the height or depth of the shape.

  Further, the shape measuring method of the present invention provides a light projecting device that irradiates line light onto the uneven shape to be measured to form a light cutting line in the uneven shape, and has an upper base of the uneven shape in the light emission axis direction. Alternatively, the image is moved by the imaging device so that the vertical width of the optical cutting line is minimized at the lower base, and the vertical width of the optical cutting line is minimized at the upper or lower base of the concavo-convex shape, The light projecting device is moved in the light emission axis direction so that the vertical width of the light cutting line is minimized at the bottom or top of the uneven shape, and the bottom or top of the uneven shape An image in which the vertical width of the light cutting line is minimized is captured by the imaging device, and the image in which the width of the light cutting line is minimized at the upper bottom of the uneven shape and the light cutting line at the lower bottom of the uneven shape. Calculating the height or depth of the concavo-convex shape based on an image having a minimum width. To.

  According to the present invention, it is possible to improve the measurement accuracy of the concavo-convex shape by suppressing measurement errors caused by fluctuations in the vertical width of the light cutting line and the luminance value of the light cutting line. In addition, since the measurement can be performed with one projector without using a projector having a complicated optical configuration, the cost can be reduced.

The figure which shows the outline of one structural example of the shape measuring apparatus in embodiment of this invention. The figure which shows the outline of the structure of general PDP The figure which shows an example of arrangement | positioning of the light projector and imaging device in embodiment of this invention The figure which shows an example of the captured image in embodiment of this invention (A) The figure for demonstrating the operation | movement which acquires the optical cutting line image in the initial state in embodiment of this invention, (b) An example of the optical cutting line image in the initial state in embodiment of this invention The figure which shows, (c) The figure which shows an example of the brightness | luminance projection image in embodiment of this invention (A) The figure for demonstrating the operation | movement which acquires the light cutting line image in the 1st movement state in embodiment of this invention, (b) The light in the 1st movement state in embodiment of this invention The figure which shows an example of a cutting line image (A) The figure for demonstrating the operation | movement which acquires the light cutting line image in the 2nd movement state in embodiment of this invention, (b) The light in the 2nd movement state in embodiment of this invention The figure which shows an example of a cutting line image The figure which shows an example of the height profile of the optical cutting line in embodiment of this invention The figure for demonstrating an example of the calculation method of the height profile of the optical section line in embodiment of this invention The figure for demonstrating an example of the calculation method of the height profile of the optical section line in embodiment of this invention The figure for demonstrating the other calculation method of the height profile of the optical section line in embodiment of this invention (A)-(c) The figure for demonstrating an example of the setting method of the rib upper bottom height calculation object area and the rib lower bottom height calculation object area in embodiment of this invention, respectively. The figure for demonstrating an example of the calculation method of the average height of the height profile of the optical section line in embodiment of this invention The figure which shows an example of the operation | movement flow of the shape measuring apparatus in embodiment of this invention Configuration diagram of a conventional shape measuring device

  Hereinafter, an embodiment of a shape measuring apparatus and a shape measuring method of the present invention will be described with reference to the drawings. In the shape measuring apparatus and the shape measuring method in this embodiment, the vertical width of the light cutting line (width in the direction perpendicular to the longitudinal direction of the light cutting line) is minimized at each of the upper and lower bases of the concavo-convex shape. By acquiring each of the above, it is possible to suppress measurement errors caused by fluctuations in the vertical width of the light section line and the luminance value of the light section line, and to measure the height or depth of the concavo-convex shape with high accuracy.

  FIG. 1 is a diagram showing an outline of a configuration example of a shape measuring apparatus according to an embodiment of the present invention. As shown in FIG. 1, this shape measuring apparatus includes a single light projecting device 2 that irradiates line light onto the concavo-convex shape of the measurement target 1, and light formed into the concavo-convex shape of the measurement target 1 by the light projection device 2. The light projecting device 2 is arranged in the direction of the light emission axis so that the vertical width of the light cutting line is minimized at each of the imaging device 3 for imaging the cutting line and the upper and lower bases of the uneven shape of the measuring object 1. 4, and a processing device 6 that calculates the height or depth of the uneven shape of the measurement object 1. In addition, the processing device 6 performs light cutting at the bottom of the concavo-convex shape of the measurement target 1 and the bottom of the concavo-convex shape of the measurement target 1 captured by the imaging device 3 and the bottom of the concavo-convex shape of the measurement target 1. The height or depth of the concavo-convex shape of the measuring object 1 is calculated based on the image in which the vertical width of the line is minimized.

  Here, the light emission axis direction 4 of the light projecting device 2 is set so that light cutting lines are simultaneously formed on the adjacent upper and lower bases of the uneven shape of the measuring object 1. Further, by simply moving the light projecting device 2 in the light emitting axis direction 4, the condensing position of the line light emitted from the light projecting device 2 is made to coincide with the upper and lower bases of the uneven shape of the measuring object 1. Set to. Thereby, the focus adjustment of the line light can be simplified.

  This shape measuring apparatus acquires an image in which the vertical width of the light cutting line is minimized at the upper or lower base of the concavo-convex shape of the measurement object 1, and further, the light is emitted from the lower or upper base of the concavo-convex shape of the measurement object 1. After obtaining images with the minimum vertical width of the cutting line, the height or depth of the concavo-convex shape is calculated based on these images. Here, when acquiring an image in which the vertical width of the light cutting line is minimized at the upper or lower base of the concavo-convex shape of the measuring object 1, the light projecting device 2 is placed in the light emission axis direction 4 and the measuring object 1. Are moved so that the vertical width of the optical cutting line is minimized at the upper or lower base of the concavo-convex shape. Similarly, when acquiring an image in which the vertical width of the light cutting line is minimized at the lower or upper base of the concavo-convex shape of the measuring object 1, the light projecting device 2 is placed in the light emission axis direction 4 and the measuring object 1. Are moved so that the vertical width of the light cutting line is minimized at the bottom or top of the concavo-convex shape.

  Specifically, the measurement object 1 is fixed to the measurement stage 7 of the shape measuring apparatus. Further, the drive device 5 includes a mechanism for moving the measurement stage 7 and moves the measurement stage 7 to a position instructed by the processing device 6. Measurement conditions such as measurement points or measurement positions are registered in advance in the processing device 6, and when the measurement points are registered, the measurement stage 7 transmits the measurement points from the light projecting device 2 to the registered measurement points. If the measurement position is registered, it moves to the registered measurement position.

  The light projecting device 2 irradiates the measurement target 1 fixed to the measurement stage 7 with a line-shaped laser beam in accordance with an instruction from the processing device 6. A light cutting line is formed in the uneven shape of the measurement object 1 by the irradiated laser light.

  Further, the light projecting device 2 is mounted on the movable portion 8, and the movable portion 8 holds the light projecting device 2 so as to be movable in the light emitting axis direction 4. The driving device 5 includes a mechanism for moving the light projecting device 2 on the movable portion 8, and moves the light projecting device 2 to a position instructed by the processing device 6, so that the shape of the measuring object 1 and the line-shaped laser are moved. Match the light collection position. Specifically, the light projecting device 2 receives the instruction from the processing device 6 so that the converging position of the line-shaped laser beam and the substantially center of the stepped portion between the upper and lower bases of the concavo-convex shape of the measurement object 1. , The upper position where the top and bottom of the concavo-convex shape of the measurement object 1 coincide with the condensing position of the line-shaped laser light, and the bottom position of the concavo-convex shape of the measurement target 1 and the line-shaped laser light It moves to three positions of the lower position where the condensing position coincides. Therefore, the light projecting device 2 is positioned at each of the three positions, that is, the initial position, the upper position, and the lower position for each measurement point, and emits laser light from each position.

  The imaging device 3 has its imaging direction substantially perpendicular to the light emission axis direction 4 of the light projecting device 2, and its center line 9 coincides with the condensing position of the line-shaped laser light emitted from the initial position, The light cutting line formed on the measuring object 1 is arranged so as to overlap the imaging surface 10 of the imaging device 3. Here, the center line 9 of the imaging device 3 is set parallel to the line direction of the line-shaped laser beam. Reflected light and scattered light from the measuring object 1 are imaged on the imaging device 3 via the lens 11. The imaging device 3 performs imaging in accordance with an instruction from the processing device 6 and transmits data of the captured image to the processing device 6. That is, the imaging device 3 images each light cutting line formed by the laser light emitted from each of the initial position, the upper position, and the lower position at each measurement point. The image when the laser beam is irradiated from the upper position becomes an image in which the vertical width of the light cutting line is minimized at the top of the concavo-convex shape of the measuring object 1, and the image when the laser beam is irradiated from the lower position is An image in which the vertical width of the light cutting line is minimized at the bottom of the uneven shape of the measurement object 1 is obtained.

  As described above, measurement conditions such as measurement points are registered in the processing device 6 in advance. Further, the processing device 6 calculates the above-described upper position and lower-side position based on an image obtained by imaging the light cutting line formed on the measurement object 1 by the light projecting device 2 positioned at the initial position, A command is given to the light projecting device 2, the imaging device 3, and the driving device 5 in accordance with the calculation result and the measurement conditions registered in advance. In addition, as described above, the processing device 6 has an image in which the vertical width of the light cutting line is minimized at the upper base of the uneven shape of the measurement object 1 and the vertical length of the light cutting line at the lower base of the uneven shape of the measurement object 1. Based on the image having the smallest width, the height or depth of the uneven shape of the measurement object 1 is calculated.

  In this embodiment, the case where the imaging device 3 is arranged so that the condensing position of the line light irradiated from the initial position and the center line 9 of the imaging device 3 coincide with each other will be described. The imaging device 3 may be moved in a direction substantially parallel to the light emission axis direction 4 of the light projecting device 2 in accordance with the movement of the light projecting device 2 to the upper position and the lower position. The movement of the imaging device 3 can be realized by the same configuration as the configuration for moving the light projecting device 2. In this way, since the light emission axis direction 4 of the light projecting device 2 and the image pickup direction of the image pickup device 3 are substantially perpendicular, the image pickup device 3 is moved in a direction substantially parallel to the light emission axis direction 4 of the light projection device 2. It is possible to adjust the focus of the image pickup apparatus 3 to the condensing position of the line light simply by moving it, and the focus adjustment by the optical system becomes unnecessary.

  The shape measuring apparatus includes a display device 12 that displays measurement results calculated by the processing device 6. The display device 12 is provided with an interface unit (not shown), and the interface unit can input measurement conditions such as measurement points while confirming the display result displayed on the display device 12.

  The shape measuring apparatus in this embodiment will be described in more detail.

  The light projecting device 2 is a line laser light source that generates a line-shaped laser beam, irradiates the measurement target 1 with the line-shaped laser beam, and forms a light cutting line in accordance with the uneven shape of the measurement target 1. . Line-shaped laser light can be produced by combining a laser light source having a single wavelength and an optical component such as a cylindrical lens or a condenser lens. As will be described later, in this embodiment, the processing device 6 calculates the center position in the vertical width direction of the optical cutting line (the direction orthogonal to the longitudinal direction of the optical cutting line). It is desirable that the beam width of the line-shaped laser beam (width in the direction perpendicular to the line direction) is small. In this embodiment, a line laser light source having a beam width of 5 μm is used. In order to focus the beam with a narrower beam width, it is desirable that the wavelength of the line laser light source is shorter. Specifically, a line laser light source having a wavelength in the range of 400 nm to 700 nm is desirable. In this embodiment, a line laser light source having a wavelength of 670 nm is used. However, the wavelength of the line laser light source needs to be within the range of the wavelength band that can be imaged by the imaging device 3.

  The light projecting device 2 is not limited to a line laser light source, and can collect the beam width to such an extent that the center position in the vertical width direction of the light cutting line can be calculated with desired accuracy, and the imaging device can capture images. Any light source having a wavelength within a possible wavelength band may be used.

  A color or monochrome CCD area sensor camera can be applied to the imaging device 3. The specification of the imaging device 3 is selected according to the size of the measurement target and the measurement accuracy. In this embodiment, a monochrome CCD area sensor camera with 300,000 pixels (480 × 625) and 255 gradations is used.

  The lens 11 may be any lens that allows the reflected light or scattered light from the measurement object 1 to be imaged on the imaging device 3 efficiently and accurately. In this embodiment, an industrial objective lens with a high magnification (× 20 times) is used.

  The measurement stage 7 may be configured to be movable to a position designated by the processing device 6. For the driving device 5 that drives the measurement stage 7, for example, a mechanism including a motor and a ball screw, a linear motor, or the like can be used. .

  For the movable portion 8, for example, a linear guide can be used. For example, a step motor or the like can be used for the driving device 5 that drives the movable portion 8.

  The light projecting device 2 and the imaging device 3 are arranged so that the angle formed by the light emitting axis of the light projecting device 2 and the central axis of the imaging device 3 is within 90 ± 0.5 degrees. In this way, it is possible to accurately image the light section line.

  As the display device 12, a device including a display device such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube) can be used.

  The shape measuring apparatus according to this embodiment can use a pattern shape such as a PDP (plasma display panel), a liquid crystal panel, an organic EL panel, or the like having a concavo-convex step of several μm or more as the measurement object 1. In this embodiment, a PDP will be described as an example.

  FIG. 2 shows an outline of a general PDP configuration. As shown in FIG. 2, a plurality of address electrodes 15 arranged in parallel are provided on the surface of the back plate glass 13 facing the front plate glass 14, and the address electrodes 15 are covered with an insulator layer 16, A plurality of vertical ribs (partitions) 17 arranged in parallel between adjacent address electrodes 15 are provided on the insulator layer 16, and the three primary color phosphor layers (R) are disposed between the adjacent vertical ribs 17. 18a, phosphor layer (G) 18b and phosphor layer (B) 18c are repeatedly formed. Although not shown, a plurality of horizontal ribs orthogonal to the vertical ribs 17 are provided on the insulator layer 16. On the other hand, on the surface of the front plate glass 14 facing the back plate glass 13, a plurality of pairs of parallel electrodes composed of the scan electrodes 19 and the sustain electrodes 20 arranged so as to be orthogonal to the address electrodes 15 are provided. Scan electrode 19 and sustain electrode 20 are covered with a dielectric layer 21, and the dielectric layer 21 is covered with a protective layer 22. In the PDP having such a structure, the address electrode 15, the vertical rib 17, the horizontal rib, the scan electrode 19, and the sustain electrode 20 are measurement targets.

  FIG. 3 shows the arrangement of the light projecting device 2 and the imaging device 3 when measuring the height of the vertical ribs 17 of the PDP. As shown in FIG. 3, when the vertical rib height 23 is measured, the light cutting lines 26 formed on the rib upper bottom surface 24 and the rib lower bottom surface 25 that form the concavo-convex shape including the vertical rib 17 are the imaging device 3. The light projecting device 2 and the image pickup device 3 are arranged so as to overlap the image pickup surface 10. In addition, in FIG. 3, the code | symbol 27 shows a horizontal rib. If it does in this way, as shown in FIG. 4, it is the optical cutting line 26 formed in each of the rib upper bottom face 24 and the rib lower bottom face 25 which correspond to the uneven | corrugated upper and lower bases on the imaging surface 10. The rib upper bottom 24a and the rib lower bottom 25a can be overlapped. In FIG. 4, the vertical axis indicates the height direction (vertical direction) 28 of the imaging surface 10, and the horizontal axis indicates the horizontal direction 29 of the imaging surface 10.

  Hereinafter, the detail of the measuring method of the vertical rib height 23 is demonstrated.

  When measuring the vertical rib height 23, first, as shown in FIG. 5A, the light projecting device 2 is placed between the rib upper bottom surface 24 and the rib lower bottom surface 25 according to a command from the processing device 6. The optical cutting line 26 is imaged in this state by positioning at an initial position 31 where the substantially center of the step portion of the light and the condensing position 30 of the line-shaped laser light irradiated by the light projecting device 2 coincide. The center line 9 of the imaging device 3 is parallel to the lateral direction 29 of the imaging surface.

  An example of an image captured in this initial state is shown in FIG. As shown in FIG. 5 (b), the optical cutting lines imaged in the initial state, that is, the rib upper base 24a and the rib lower base 25a have a vertical width of a certain level or more. The processing device 6 generates a luminance projection image obtained by performing luminance projection in the horizontal direction 29 on the imaging surface from the light cutting line image in the initial state. Luminance projection is a process of accumulating the luminance of pixels in a certain direction. FIG. 5C shows an example of the luminance projection image. In the luminance projection image shown in FIG. 5C, the horizontal axis orthogonal to the height direction 28 of the imaging surface indicates the projection luminance value 32.

  In this embodiment, since a monochrome CCD area sensor camera with 8 bit gradation is used, the luminance is changed from 255 gradation to 0 gradation. The range of luminance to be projected is set from 255 to 75, and luminance below 74 is regarded as a noise component and not reflected in the projected luminance value.

  Next, the processing device 6 sets the threshold values 33 and 34 for the projected luminance value, and the position in the height direction of the rib upper base 24a (hereinafter referred to as “rib”) from the intersection of the luminance projected waveform 35 and the threshold values 33 and 34. And a position in the height direction of the rib lower bottom 25a (hereinafter referred to as “rib lower bottom position 37”), and further, a rib upper bottom position 36 and a rib lower bottom position 37 are calculated. The center position 38 is calculated. The calculation of the rib lower bottom position 37 will be specifically described as an example. The center of two intersections of the luminance projection waveform 35 and the threshold value 34 with respect to the rib lower bottom 25a is calculated as the rib lower bottom position 37. Similarly, the rib upper base position 36 is calculated using the threshold value 33 for the rib upper base 24a.

  In this embodiment, since the vertical rib 17 is imaged so that the accumulated luminance value of the rib lower bottom 25a is larger than the rib upper bottom 24a, the lower rib is used by using a threshold 34 larger than the threshold 33. A bottom position 37 is calculated, and a rib upper bottom position 36 is calculated using a threshold 33 smaller than the threshold 34. The threshold values 33 and 34 are based on the size of the imaging surface 10, the maximum value of the projected luminance value, the number of vertical ribs 17 (imaging range) overlapping the imaging surface 10, the intensity of the laser light emitted from the light projecting device 2, and the like. And set as appropriate. In this embodiment, the threshold value 33 of the rib upper base 24a is set to 1000 gradations or more, and the threshold value 34 of the rib lower base 25a is set to 30000 gradations or more. Note that the maximum value of the projected luminance value is 159375 since the number of pixels in the lateral direction 29 on the imaging surface is 625 and the maximum luminance is 255.

  Next, the processing device 6 determines the initial position 31 of the light projecting device 2 registered in advance, the difference between the rib upper bottom position 36 and the center line 9 of the imaging device 3, the inclination angle of the imaging device 3, and the imaging device. From the resolution of 3, the amount of movement of the light projecting device 2 to the upper position 39 where the condensing position 30 of the line-shaped laser light irradiated by the light projecting device 2 and the rib upper bottom surface 24 coincide with each other is calculated. As shown to (a), the light projection apparatus 2 is positioned to the upper side position 39, and a light cutting line is imaged in this state.

  An example of an image captured in the first movement state is shown in FIG. As shown in FIG. 6 (b), in the light section line image captured in the first movement state, the laser beam condensing position 30 and the rib upper surface 24 coincide with each other. The beam width of the line-shaped laser beam on the bottom surface 24 is minimized. Therefore, the optical cutting line formed on the rib upper bottom surface 24, that is, the vertical width of the rib upper bottom 24b is minimized. On the other hand, the optical cutting line formed on the bottom rib bottom surface 25, that is, the vertical width of the bottom rib bottom 25b is larger than the bottom rib bottom 25a shown in FIG.

  Next, the processing device 6 includes the initial position 31 of the light projecting device 2 registered in advance, the difference between the rib bottom base position 37 and the center line 9 of the imaging device 3, the inclination angle of the imaging device 3, and the imaging device. 3, the amount of movement of the light projecting device 2 to the lower position 40 where the converging position 30 of the line-shaped laser light irradiated by the light projecting device 2 and the rib bottom surface 25 coincide is calculated. As shown in FIG. 7A, the light projecting device 2 is positioned at the lower position 40, and the light section line is imaged in this state.

  An example of an image captured in the second movement state is shown in FIG. As shown in FIG. 7B, in the optical section line image captured in the second movement state, the laser beam condensing position 30 and the rib lower bottom surface 25 coincide with each other. The beam width of the line-shaped laser beam on the bottom surface 25 is minimized. Therefore, the optical cutting line formed on the rib lower bottom surface 25, that is, the vertical width of the rib lower bottom 25c is minimized. On the other hand, the optical cutting line formed on the rib upper bottom surface 24, that is, the vertical width of the rib upper bottom 24c is larger than the rib upper bottom 24a shown in FIG.

  The processing device 6 calculates the height profile of each light cutting line from the images captured in the first and second moving states, and calculates the rib upper base position 36 and the rib lower base position calculated based on the luminance projection image. 37 with respect to the center position 38 of the light source 37, the height profile of the optical section line calculated from the image captured in the first movement state (the height profile of the rib upper base 24b) for the region 41 above the center position 38. ) Using the height profile of the optical cutting line (height profile of the rib bottom bottom 25c) calculated from the image captured in the second movement state for the region 42 below the center position 38. Then, a height profile of the optical section line shown in FIG. 8 is created. This profile corresponds to the height profile of the light cutting line of the image in which the vertical width of the light cutting line is minimized at each of the rib upper bottom and the rib lower bottom.

  Here, an example of a method for calculating the height profile of the light section line will be specifically described with reference to FIGS. In the method shown in FIGS. 9 and 10, the height profile 43 of the light section line is created from the luminance value of each pixel constituting each line arranged in the horizontal direction 29 on the imaging surface (captured image).

That is, as shown in FIG. 9, when calculating the height position of the light cutting line in the attention line (N) 44 along the height direction 28 of the imaging surface (captured image), first, the attention line (N) 44 is displayed. Using adjacent lines, the luminance value of each pixel constituting the target line (N) 44 is smoothed. For example, when the setting parameter of the smoothing process is 3, the luminance value of each pixel constituting each of the line (N−1) 45 and the line (N + 1) 46 adjacent to the target line (N) 44 is used. Thus, the luminance value of each pixel constituting the target line (N) 44 is smoothed. The calculation formula is
Xn ′ (N) = (Xn (N−1) + Xn (N) + Xn (N + 1)) / 3
The calculation for smoothing is performed for each pixel arranged in the height direction to generate a luminance data line (N) 47 in which the luminance value of each pixel of the target line (N) 44 is smoothed. To do. Xn ′ (N) is the luminance value of the nth pixel of the luminance data line (N) 47, Xn (N−1) is the luminance value of the nth pixel of the line (N−1) 45, and Xn (N ) Is the luminance value of the nth pixel of the target line (N) 44, and Xn (N + 1) is the luminance value of the nth pixel of the line (N + 1) 46. In this embodiment, the smoothing size is 5. That is, using two lines adjacent to each side of the target line (N), specifically, using the line (N-2), the line (N-1) and the line (N + 1), and the line (N + 2), The luminance value of each pixel constituting the line (N) is smoothed.

Next, a differential waveform of the luminance data line (N) 47 is generated. The differential value of the luminance value X ′ (n) of the pixel of interest (n) 48 on the luminance data line (N) 47 is the difference value between the luminance value X ′ of adjacent pixels on the luminance data line (N) 47 and To do. For example, when the setting parameter of the differentiation process is 3, the luminance value X of the pixel (n−1, n−2, n−3) 49 and the pixel (n + 1, n + 2, n + 3) 50 adjacent to the target pixel (n) 48. 'Is used to determine the differential value of the luminance value X ′ (n) of the pixel of interest (n) 48. The calculation formula is
X ″ (n) = (X ′ (n + 3) + X ′ (n + 2) + X ′ (n + 1)) − (X ′ (n−3) + X ′ (n−2) + X ′ (n−1))
The calculation for obtaining the differential value is performed for each pixel constituting the luminance data line (N) 47, and the differential waveform 51 shown in FIG. 10 is generated. X ″ (n) is a differential value of the luminance value X ′ (n) of the nth pixel on the luminance data line (N) 47, and X ′ (n + 3) to X ′ (n + 1) are luminance data lines ( N) The luminance values of the (n + 3) th to (n + 1) th pixels on 47, and X ′ (n−3) to X ′ (n−1) are (n−3) on the luminance data line (N) 47. This is the luminance value of the n th to (n−1) th pixels. In this embodiment, the smoothing size is 10. That is, using ten pixels adjacent to both sides of the target pixel (n), specifically, using the pixels (n-10) to (n-1) and the pixels (n + 1) to (n + 10), Differentiate pixel (n).

  Next, the height position 52 of the light section line in the target line (N) 44 is calculated from the generated differential waveform 51. In FIG. 10, the axis orthogonal to the height direction 28 of the imaging surface (captured image) indicates the differential value 53. The height position 52 is a point where the differential waveform 51 crosses the zero point 56 first after the differential threshold value 54 exceeds the differential threshold 54 and reaches the maximum value 55. In this embodiment, the differential threshold value 54 is set to 500.

  By performing the above processing for each line arranged in the lateral direction 29 on the imaging surface (captured image), the height profile 43 of the light section line shown in FIG. 9 can be obtained.

Next, another method for calculating the height profile of the light section line will be specifically described with reference to FIG. As shown in FIG. 11, when calculating the height position of the light section line in the attention line (N) 57 along the height direction 28 of the imaging surface (captured image), from the pixels constituting the attention line (N) 57. A labeling process for extracting pixels having a luminance value equal to or higher than a threshold is performed, and the center coordinates 58 of the extracted pixels are calculated as the height position of the light section line in the target line (N) 57. The calculation formula is
Center coordinates = (Y1 + Y2 +... + Yn) / n
It is. Note that n is the number of pixels having a luminance value equal to or greater than the threshold, and Y1 to Yn are coordinates of each pixel having a luminance value equal to or greater than the threshold. FIG. 11 illustrates a case where three pixels having coordinates of 103, 104, and 106 are extracted as pixels having a threshold value of 200 and a luminance value equal to or higher than the threshold value. In this case, the center coordinate 58 is 104.33.

  By performing the above processing for each line arranged in the horizontal direction 29 on the imaging surface (captured image), the light cutting line height profile 59 shown in FIG. 11 can be obtained.

  As described above, by calculating the height profile of each light cutting line from the images captured in the first and second moving states, the vertical width of the light cutting line at each of the rib upper bottom and the rib lower bottom is determined. It is possible to create a height profile of the light cutting line of the image that is minimized.

  The region 41 above the center position 38 of the image captured in the first movement state and the region 42 below the center position 38 of the image captured in the second movement state are combined. Alternatively, an image in which the vertical width of the light cutting line is minimized at each of the rib upper bottom and the rib lower bottom may be calculated, and the height profile of the light cutting line may be calculated from the generated image.

  Next, the processing device 6 sets a rib upper bottom height calculation target area and a rib lower bottom height calculation target area for the height profile of the created light section line. An example of a setting method of the rib upper bottom height calculation target area and the rib lower bottom height calculation target area will be specifically described with reference to FIG. FIG. 12 shows three examples of the height profile of the light section line. 12A to 12C, the vertical axis corresponds to the height direction 28 of the imaging surface, and the horizontal axis corresponds to the horizontal direction 29 of the imaging surface.

  When there are only one rib as shown in FIG. 12A, first, the height profile 60a of the optical cutting line is set to the rib upper bottom areas 63a, 65a, 67a and the rib lower bottom areas 62a, 64a, 66a by the threshold value 61a. , 68a.

  The threshold value is set as%, with 100% between the MAX value and the MIN value of the height profile of the optical cutting line. In this embodiment, the threshold 61a is set to 50%. That is, the center between the MAX value and the MIN value is the threshold value.

  Next, when the width of the area defined by the threshold 61a is equal to or less than the effective rib width threshold, it is determined that the area is neither the rib upper bottom area nor the rib lower bottom area. That is, it is determined that the areas 63a, 64a, and 67a are neither the rib upper bottom area nor the rib lower bottom area.

  Next, when the areas determined to be neither the rib upper bottom area nor the rib lower bottom area are continuous, the areas are connected. That is, the areas 63a and 64a are connected to form an area 69a. Further, when an area that is determined to be neither the rib upper bottom area nor the rib lower bottom area is surrounded by the same type of areas, the areas are connected. That is, the areas 66a, 67a, and 68a are connected to become a rib lower bottom area 70a.

  If there is only one rib upper base area in the field of view, the rib upper base area is set as the rib upper base height calculation target area, and the areas adjacent to the rib upper base area are ribbed. Set to the lower bottom height calculation target area. That is, the rib upper bottom area 65a is set as a rib upper bottom height calculation target area, and the rib lower bottom area 62a and the rib lower bottom area 70a are set as rib lower bottom height calculation target areas.

  Also, as shown in FIG. 12 (b), when there are more ribs than one and no two peaks, first, the height profile 60b of the optical cutting line is set to the rib upper bottom areas 63b, 65b, 67b and the rib lower bottom using the threshold value 61b. The area is divided into areas 62b, 64b, and 66b. In this embodiment, the threshold 61b is set to 50%.

  Next, when the width of the area defined by the threshold 61b is equal to or less than the effective rib width threshold, it is determined that the area is neither the rib upper bottom area nor the rib lower bottom area. That is, it is determined that the areas 63b and 64b are neither the rib upper bottom area nor the rib lower bottom area.

  Next, when the areas determined to be neither the rib upper bottom area nor the rib lower bottom area are continuous, the areas are connected. That is, the area 63b and the area 64b are connected to form an area 68b.

  If there are two rib upper bottom areas in the field of view through the above processing, the area sandwiched between the two areas is set as the rib lower bottom height calculation target area. On the other hand, the rib upper bottom area not surrounded by the rib lower bottom area is not subject to calculation. That is, the rib lower bottom area 66b sandwiched between the rib upper bottom area 65b and the rib upper bottom area 67b is set as a rib lower bottom height calculation target area and is surrounded by the rib lower bottom area 62b and the rib lower bottom area 66b. The rib upper bottom area 65b is set as a rib upper bottom height calculation target area.

  When there are two or more ribs as shown in FIG. 12C, first, the height profile 60c of the optical cutting line is set to the rib upper bottom areas 63c, 65c, 67c and the rib lower bottom areas 62c, 64c by the threshold value 61c. It is divided into 66c and 68c. In this embodiment, the threshold 61c is set to 50%.

  Next, when the width of the area defined by the threshold 61c is equal to or less than the effective rib width threshold, it is determined that the area is neither the rib upper bottom area nor the rib lower bottom area. That is, it is determined that the areas 63c and 64c are neither the rib upper bottom area nor the rib lower bottom area.

  Next, when the areas determined to be neither the rib upper bottom area nor the rib lower bottom area are continuous, the areas are connected. That is, the area 63c and the area 64c are connected to form an area 69c.

  If there are two rib upper bottom areas in the field of view through the above processing, the area sandwiched between the two areas is set as the rib lower bottom height calculation target area. On the other hand, all rib upper bottom areas surrounded by the rib lower bottom area are subject to calculation. That is, the rib bottom bottom area 66c sandwiched between the rib top bottom area 65c and the rib top bottom area 67c is set as the rib bottom bottom height calculation target area and is surrounded by the rib bottom bottom area 62c and the rib bottom bottom area 66c. The rib upper bottom area 65c, and the rib upper bottom area 67c surrounded by the rib lower bottom area 66c and the rib lower bottom area 68c are set as the rib upper bottom height calculation target area.

  As described above, the processing device 6 sets the rib upper base height calculation target area and the rib lower base height calculation target area from the height profile of the light cutting line.

  Next, the processing device 6 determines the difference between the average height of the optical cutting line height profile in the rib upper bottom height calculation target area and the average height of the optical cutting line height profile in the rib lower bottom height calculation target area. And the vertical rib height 23 is calculated based on the difference and the inclination angle of the imaging device 3.

  Here, an example of a method for calculating the average height of the height profile of the light section line will be specifically described with reference to FIG. In FIG. 13, the vertical axis corresponds to the height direction 28 of the imaging surface, and the horizontal axis corresponds to the horizontal direction 29 of the imaging surface.

  As shown in FIG. 13, the rib upper base height calculation target area 72 and the rib lower base height calculation target area 73 defined by the threshold 71 are multiplied by a predetermined ratio A and ratio B, respectively. An upper bottom average height calculation area 74 and a rib lower bottom average height calculation area 75 are set, and the average height is calculated in each area. However, the rib upper base average height calculation area 74 is set so that the centers of the rib upper base height calculation target area 72 and the rib upper base average height calculation area 74 coincide. Similarly, the rib lower bottom average height calculation area 75 is set such that the centers of the rib lower bottom height calculation target area 73 and the rib lower bottom average height calculation area 75 coincide. The ratios A and B are 0 <A <1 and 0 <B <1. In this embodiment, A = 0.5 and B = 0.5. Here, the rib upper base height calculation target area and the rib lower base height calculation target area are multiplied by a predetermined ratio A and ratio B, respectively, to obtain the average height using the average value in the flat portion. This is because of the demand. That is, by multiplying the ratios A and B in this way, it is possible to make the calculation of the average height less susceptible to the influence of the edge portion of the rib.

  Next, an operation flow when measuring the vertical rib height 23 of the shape measuring apparatus described above will be described with reference to FIG.

  First, the rear plate glass 13 is fixed to the measurement stage 7. On the rear plate glass 13, vertical ribs 17 to be measured 1 are formed. Next, the measurement stage 7 is moved to a measurement position registered in the processing device 6 in advance.

  Next, a light cutting line image in an initial state in which the condensing position 30 of the line-shaped laser light irradiated by the light projecting device 2 is made to coincide with the approximate center of the step portion between the rib upper bottom surface 24 and the rib lower bottom surface 25. (Step S1), and a luminance projection image obtained by luminance projection in the lateral direction 29 of the imaging surface is generated from the light section line image (step S2).

  Next, in order to detect the rib upper base 24a and the rib lower base 25a, threshold values 33 and 34 of the projection luminance value are set, and the rib upper base position 36 and the rib lower bottom position are determined from the intersection of the luminance projection waveform 35 and the threshold value. 37 is calculated.

  Next, from the initial position 31 of the light projecting device 2 registered in advance, the difference between the rib upper base position 36 and the center line 9 of the imaging device 3, the inclination angle of the imaging device 3, and the resolution of the imaging device 3, The amount of movement of the light projecting device 2 to the upper position 39 is calculated, and the light projecting device 2 is positioned at the upper position 39 (step S3).

  Next, an optical section line image (a) is acquired in a first movement state in which the condensing position 30 of the line-shaped laser light irradiated by the light projecting device 2 is made to coincide with the rib upper bottom surface 24 (step S4).

  Next, from the initial position 31 of the light projecting device 2 registered in advance, the difference between the rib bottom base position 37 and the center line 9 of the imaging device 3, the inclination angle of the imaging device 3, and the resolution of the imaging device 3, The amount of movement of the light projecting device 2 to the lower position 40 is calculated, and the light projecting device 2 is positioned at the lower position 40 (step S5).

  Next, a light section line image (b) is acquired in the second movement state in which the condensing position 30 of the line-shaped laser light irradiated by the light projecting device 2 is made to coincide with the rib bottom bottom surface 25 (step S6).

  Next, a height profile of the light cutting line is obtained from the light cutting line image (a) in the first movement state acquired in step S4 (step S7). The height profile of the light section line is obtained, for example, by performing smoothing processing and differentiation processing for each line. That is, the luminance value of each pixel of the target line is smoothed and further differentiated to generate a differential waveform 51. The differential waveform 51 crosses the differentiation threshold 54 and reaches the maximum value 55, and then intersects with the zero point 56 first. The point is calculated as the height position 52 of the light cutting line in the target line. By performing this process for each line, the height profile of the light section line in the light section line image is obtained.

  Next, as in step S7, the height profile of the light cutting line is obtained from the light cutting line image (b) in the second movement state acquired in step S6 (step S8).

  Next, with reference to the center position 38 of the rib upper base position 36 and the rib lower base position 37 calculated based on the luminance projection image, the region 41 above the center position 38 is shown in the optical section line image (a). For the region 42 below the center position 38 using the height profile of the optical section line (height profile of the rib upper base 24b), the height profile (ribs) of the optical section line in the optical section line image (b) is used. Using the height profile of the lower base 25c, a height profile of the optical section line connecting them is created (step S9).

  Next, a rib upper base height calculation target area and a rib lower base height calculation target area are set for the light cutting line height profile created in step S9, and light in the rib upper base height calculation target area is set. A difference between the average height of the cutting line height profile and the average height of the optical cutting line height profile in the rib bottom bottom height calculation target area is obtained, and based on the difference and the inclination angle of the image pickup device 3, The rib height 23 is calculated (step S10). As the average height of the height profile of the light section line, for example, the rib upper base height calculation target area 72 and the rib lower base height calculation target area 73 are multiplied by a predetermined ratio A and ratio B, respectively. The rib upper bottom average height calculation area 74 and the rib lower bottom average height calculation area 75 are set, and the average height in each area is calculated.

  Next, the measurement stage 7 is moved to the next measurement position registered in advance in the processing device 6 (step S11).

  By repeating the above operation for each measurement position registered in the processing device 6 in advance, the heights of all the vertical ribs 17 formed on the back plate glass 13 can be measured.

  Next, the measurement accuracy of the shape measuring apparatus in this embodiment and the conventional shape measuring apparatus shown in FIG.

  In the case of the conventional shape measuring apparatus, even if the laser beam is condensed on one of the upper and lower bases and the beam width at the condensing point is 5 μm, the height of the vertical rib is about 150 μm. An image is acquired in which the width spreads to about 30 μm, the beam width differs between measurement sites, and the center position of the laser intensity is also greatly shifted within the range of the beam width. On the other hand, in the case of the shape measuring apparatus according to this embodiment, the beam width is 5 μm at each measurement site, and an image without a change in the center position of the laser intensity can be acquired. It hardly occurs.

  Therefore, when a height of 150 μm is measured, a difference of nearly 10 μm occurs as a measured value between the shape measuring device in this embodiment and the conventional shape measuring device. Therefore, the shape measuring apparatus in this embodiment can measure the height or depth of the concavo-convex shape with higher accuracy than the conventional shape measuring apparatus.

  As described above, each of the measurement sites such as the upper and lower bases of the concavo-convex shape is irradiated with the line light in a state where the beam width is the smallest, and the vertical width of the light cutting line in each of the measurement sites is By obtaining the minimum images, it is possible to suppress measurement errors caused by fluctuations in the vertical width of the light cutting line and the luminance value of the light cutting line, and to improve the measurement accuracy of the uneven shape. In addition, measurement can be performed without using a projector having a complicated optical configuration, and measurement can be performed with a single projector.

  The shape measuring apparatus and the shape measuring method according to the present invention can improve the measurement accuracy of the concavo-convex shape, and are flat panels represented by LCD (Liquid Crystal Display) and PDP (Plasma Display Panel). -It can be used to measure the pattern shape of the display.

DESCRIPTION OF SYMBOLS 1 Measurement object 2 Light projection apparatus 3 Imaging apparatus 4 Light-emission axial direction 5 Drive apparatus 6 Processing apparatus 7 Measurement stage 8 Movable part 9 Centerline 10 Imaging surface 11 Lens 12 Display apparatus 13 Back plate glass 14 Front plate glass 15 Address electrode 16 Insulator Layer 17 Vertical rib 18a Phosphor layer (R)
18b Phosphor layer (G)
18c phosphor layer (B)
DESCRIPTION OF SYMBOLS 19 Scan electrode 20 Sustain electrode 21 Dielectric layer 22 Protective layer 23 Vertical rib height 24 Rib upper bottom surface 24a-24c Rib upper bottom 25 Rib lower bottom surface 25a-25c Rib lower bottom 26 Optical cutting line 27 Horizontal rib 28 Imaging surface height Length direction 29 Horizontal direction of imaging surface 30 Condensing position of laser beam 31 Initial position 32 Projected luminance value 33 Threshold value for rib upper base 34 Threshold value for rib lower bottom 35 Luminance projection waveform 36 Rib upper bottom position 37 Rib lower bottom position 38 Rib Center position of upper bottom position and rib lower bottom position 39 Upper position 40 Lower position 41 Upper area 42 Lower area 43 Optical cutting line height profile 44 Line of interest (N)
45 Line adjacent to the line of interest (N-1)
46 Line adjacent to the line of interest (N + 1)
47 Luminance data line (N)
48 pixel of interest (n)
49 Pixels adjacent to the pixel of interest (n-3, n-2, n-1)
50 Pixels adjacent to the target pixel (n + 1, n + 2, n + 3)
51 Differential waveform 52 Height position of optical cutting line in line of interest 53 Differential value 54 Differential threshold 55 Maximum value of differential waveform 56 Zero point 57 Line of interest (N)
58 Center coordinates 59 Optical cutting line height profile 60a Optical cutting line height profile 61a Threshold 63a, 65a, 67a Rib upper bottom area 62a, 64a, 66a, 68a, 70a Rib lower bottom area 69a Rib upper bottom area and rib Area that is not any of the lower bottom area 60b Height profile of the optical cutting line 61b Threshold value 63b, 65b, 67b Rib upper bottom area 62b, 64b, 66b Rib lower bottom area 68b Neither rib upper bottom area nor rib lower bottom area Area 60c Height profile of optical cutting line 61c Threshold 63c, 65c, 67c Rib upper bottom area 62c, 64c, 66c, 68c Rib lower bottom area 69c Area which is neither rib upper bottom area nor rib lower bottom area 71 Threshold 72 Rib Upper bottom height calculation target area 73 Rib lower bottom height calculation Elephant area 74 rib upper bottom average height calculation area 75 ribs under the bottom average height calculation area 101 inspection stage 102 to be inspected 103a, 103b projecting device 104 lens 105 imaging device 106 processor

Claims (7)

A light projecting device that irradiates the uneven shape of the measurement object with line light;
An imaging device for imaging a light cutting line formed in the concavo-convex shape by the light projecting device;
A driving device that moves the light projecting device in the direction of the light emission axis so that the width of the light cutting line is minimized at each of the upper and lower bases of the concavo-convex shape;
Based on the image captured by the imaging device, the width of the light cutting line is minimized at the top of the uneven shape, and the image of the bottom of the uneven shape of the light cutting line is minimized, A processing device for calculating the height or depth of the uneven shape;
A shape measuring apparatus comprising:   The shape measuring apparatus according to claim 1, wherein a light emission axis direction of the light projecting device and an imaging direction of the imaging device are substantially perpendicular.   The drive device further includes a mechanism for moving the imaging device in parallel with the light emission axis direction of the light projecting device, moving the imaging device in parallel with the light emission axis direction of the light projection device, and 3. An image in which the width of the optical cutting line is minimized at the upper base of the concavo-convex shape and an image in which the width of the optical cutting line is minimized at the lower base of the concavo-convex shape are captured. The shape measuring device according to any one of the above. A light projection device that irradiates the uneven shape to be measured with line light to form a light cutting line in the uneven shape, and the width of the light cutting line at the upper or lower base of the uneven shape in the light emission axis direction thereof. The image is captured by the imaging device so that the width of the light cutting line is minimized at the upper or lower base of the concavo-convex shape,
The light projecting device is moved in the light emitting axis direction so that the width of the light cutting line is minimized at the bottom or top of the concavo-convex shape, and the light at the bottom or top of the concavo-convex shape Taking an image with the smallest cutting line width by the imaging device,
The height or depth of the concavo-convex shape based on an image in which the width of the optical cutting line is minimum at the upper base of the concavo-convex shape and an image in which the width of the optical cutting line is minimum at the lower base of the concavo-convex shape A shape measuring method characterized by calculating the thickness.   A pixel having a brightness value equal to or greater than a threshold value in an image in which the width of the light cutting line is minimum at the top of the uneven shape and a brightness value in an image in which the width of the light cutting line is minimum at the bottom of the uneven shape The shape measuring method according to claim 4, wherein the height or depth of the concavo-convex shape is calculated based on pixels that are equal to or greater than a threshold value.   The shape measuring method according to claim 4, wherein a light emission axis direction of the light projecting device and an imaging direction of the imaging device are substantially perpendicular.   An image in which the width of the light cutting line is minimized at the top of the concavo-convex shape and the light cutting at the bottom of the concavo-convex shape by moving the imaging device parallel to the light emission axis direction of the light projecting device The shape measuring method according to claim 4, wherein an image having a minimum line width is captured.