JP4053951B2 - Method and apparatus for measuring height of protrusion - Google Patents

Description

  The present invention relates to a method and an apparatus for measuring the height of a protrusion, and more particularly, to a method and an apparatus for efficiently measuring the height of a protrusion such as a minute bump provided on a circuit board or LSI chip.

  Many LSI bumps are provided on an LSI chip such as a circuit board or BGA (Bump Grid Array) for use as wiring electrodes. As described above, measuring the height of the protrusion formed on the surface of a certain work is important in confirming that the protrusion having the dimension according to the specification is formed for each lot. In particular, in the case of a large number of bumps formed as wiring electrodes on a circuit board or LSI chip, variations in dimensions can cause electrical contact failure. In stages, it is necessary to measure the height of individual bumps.

As a general method for measuring the height of a protrusion, a method using a displacement meter and a method using confocal are known. The former is a method of measuring the distance to the workpiece surface and the distance to the top of the projection using, for example, a laser displacement meter disposed above the workpiece, and recognizing the difference between the two as the height of the projection. On the other hand, the latter is a method of observing the protrusion from above using an optical instrument such as a microscope and measuring the peak height from the in-focus position. Further, for example, Patent Document 1 below discloses a method of measuring the height by illuminating a projection and imaging a shadow area.
JP 2001-298036 A

  The conventional method for measuring the height of protrusions has a problem that it is difficult to measure the heights of many protrusions at high speed. For example, in the method using the displacement meter described above, since it is necessary to accurately irradiate the projections with a minute spot such as a laser displacement meter, accurate alignment is required for each projection, and a large number of projections are required. It takes a lot of time to measure the total number of workpieces on which slabs are formed. Further, in the method using confocal, since the field of view of an optical instrument such as a microscope is relatively narrow, only a few protrusions can be measured at a time. Furthermore, in the method disclosed in the above-mentioned Patent Document 1, it is difficult to uniformly irradiate a wide range of illumination from an oblique direction, and it is also difficult to efficiently measure a large number of protrusions.

  Therefore, an object of the present invention is to provide a projection height measuring method and a measuring apparatus capable of measuring the heights of many projections at high speed.

(1) According to a first aspect of the present invention, in the method for measuring the height of a protrusion for measuring the height of the protrusion formed on the workpiece surface,
An imaging stage for capturing a predetermined area on the workpiece surface including the projection to be measured from the direction of the elevation angle θ and obtaining a planar image including the projection corresponding image;
An outline extraction stage for causing a computer to execute a process of extracting the outline of the projection corresponding image based on the planar image obtained in the imaging stage;
Under the assumption that the projection to be measured is conical, the computer recognizes the portion corresponding to the bottom diameter portion of the projection on the projection corresponding image as the diameter corresponding portion based on the contour information. A diameter bus bar recognition stage for causing a portion corresponding to the bus bar portion of the projection on the projection corresponding image to be recognized as a bus bar corresponding portion, and executing a process of obtaining a length D of the diameter corresponding portion and a length L of the bus bar corresponding portion;
A height calculation stage for causing the computer to execute a process of calculating the height h of the protrusion based on the elevation angle θ, the length D of the diameter corresponding portion, and the length L of the bus corresponding portion;
Is to do.

(2) According to a second aspect of the present invention, in the projection height measuring method according to the first aspect described above,
When there are a plurality of protrusions on the work surface, the critical angle of the elevation angle θ at which the plurality of protrusion corresponding images overlap each other at the imaging stage is defined as θ1, and the angle formed between the conical bus forming the protrusion and the work surface Is set to a range of θ1 <θ <θ2 when the angle θ is θ2.

(3) According to a third aspect of the present invention, in the projection height measuring method according to the first or second aspect described above,
In the contour extraction stage, the planar image obtained in the imaging stage is binarized, and the part where the pixel value changes is recognized as a boundary line, or the planar image obtained in the imaging stage is differentiated, A portion where the pixel value takes a maximum value is recognized as a boundary line.

(4) According to a fourth aspect of the present invention, in the projection height measuring method according to the first to third aspects described above,
At the diameter bus recognition stage, the maximum horizontal width of the protrusion corresponding image is recognized as the length D of the diameter corresponding portion, and the maximum vertical width of the protrusion corresponding image is recognized as the length L of the bus corresponding portion. Is.

(5) According to a fifth aspect of the present invention, in the projection height measuring method according to the first to fourth aspects described above,
When there are a plurality of protrusions on the workpiece surface, in the diameter generatrix recognition stage, the lengths D and L for each protrusion corresponding image are recognized, and the position coordinates for a predetermined feature point are recognized, The position and height of each protrusion are measured.

(6) According to a sixth aspect of the present invention, in the projection height measuring method according to the first to fifth aspects described above,
At the imaging stage, a projection corresponding image is obtained on a projection plane that intersects the workpiece surface at an angle (90 ° -θ),
In the height calculation stage, the height h of the protrusion is obtained using an equation h = (LD / 2 · sin θ) / cos θ.

(7) According to a seventh aspect of the present invention, in the projection height measuring method according to the sixth aspect described above,
At the imaging stage, a projection plane that intersects the workpiece surface at an angle (90 ° -θ) is defined, and imaging is performed using an area sensor in which imaging pixels are two-dimensionally arranged on the projection plane. Is.

(8) According to an eighth aspect of the present invention, in the projection height measuring method according to the first to fifth aspects described above,
At the imaging stage, a projection corresponding image is obtained by projecting the projection in the direction of the elevation angle θ on the projection plane parallel to the workpiece surface,
In the height calculation stage, the height h of the protrusion is obtained using the equation h = (LD / 2) · tan θ.

(9) According to a ninth aspect of the present invention, in the projection height measuring method according to the eighth aspect described above,
Define a projection plane parallel to the workpiece surface at the imaging stage, prepare a line sensor with one-dimensional array of pixels on the projection plane, and move the line sensor or workpiece along the projection plane In this way, imaging is performed.

(10) According to a tenth aspect of the present invention, in the projection height measuring apparatus for measuring the height of the projection formed on the workpiece surface,
An imaging camera for imaging an imaging target area on the workpiece surface from the direction of the elevation angle θ;
A scanning unit that scans the imaging camera so that the imaging target region moves on the workpiece surface;
An illumination unit for illuminating the imaging target region;
A control processing device that controls the imaging camera, the scanning unit, and the illumination unit, and executes processing necessary for measurement;
To the control processing device,
An imaging process for capturing a planar image including a projection corresponding image of a projection to be measured by controlling an imaging camera, a scanning unit, and an illumination unit;
An outline extraction process for extracting the outline of the projection corresponding image based on the planar image obtained by the imaging process; and
Under the assumption that the projection to be measured is conical, the part corresponding to the bottom diameter part of the projection on the projection-corresponding image is recognized as the diameter-corresponding part based on the information on the contour line, and the projection correspondence A diameter busbar recognition process for recognizing a portion corresponding to a busbar portion of the protrusion on the image as a busbar corresponding portion, and obtaining a length D of the diameter corresponding portion and a length L of the busbar corresponding portion;
A height calculation process for calculating the height h of the protrusion based on the elevation angle θ, the length D of the diameter corresponding portion, and the length L of the bus corresponding portion;
It has a function to execute.

(11) According to an eleventh aspect of the present invention, in the projection height measuring apparatus according to the tenth aspect described above,
The contour line extraction process binarizes the planar image obtained in the imaging stage and recognizes the portion where the pixel value changes as a boundary line, or differentiates the planar image obtained in the imaging stage, and the pixel value is This is executed by recognizing the portion having the maximum value as a boundary line.

(12) According to a twelfth aspect of the present invention, in the projection height measuring apparatus according to the tenth or eleventh aspect described above,
Diameter bus recognition processing is executed by recognizing the maximum horizontal width of the protrusion-corresponding image as the length D of the diameter-corresponding portion and recognizing the maximum vertical width of the protrusion-corresponding image as the length L of the busbar-corresponding portion. It is what you do.

(13) In a thirteenth aspect of the present invention, in the projection height measuring apparatus according to the tenth to twelfth aspects described above,
In addition to recognizing the lengths D and L for each projection-corresponding image, it has a function of recognizing the position coordinates of a predetermined feature point so that the position and height of each projection can be measured. is there.

(14) According to a fourteenth aspect of the present invention, in the projection height measuring apparatus according to the tenth to thirteenth aspects described above,
An imaging camera is configured by an area sensor configured by two-dimensionally arranging imaging pixels on a projection plane that intersects the workpiece surface at an angle (90 ° −θ),
The control processing device is made to perform processing for obtaining the height h of the protrusion using the formula h = (LD / 2 · sin θ) / cos θ.

(15) According to a fifteenth aspect of the present invention, in the projection height measuring apparatus according to the tenth to thirteenth aspects described above,
An imaging camera is configured by a line sensor that is arranged in one dimension so as to be parallel to the workpiece surface and configured by imaging pixels that can image the protrusion from the direction of the elevation angle θ.
The scanning unit has the function of scanning the line sensor or workpiece along the projection plane parallel to the workpiece surface,
The control processing device is made to perform processing for obtaining the height h of the protrusion using the formula h = (L−D / 2) · tan θ.

(16) According to a sixteenth aspect of the present invention, there is provided a program for causing a computer to function as the projection height measuring apparatus according to the tenth to fifteenth aspects.

  According to the method and apparatus for measuring the height of protrusions according to the present invention, it is possible to measure the heights of many protrusions at high speed.

  Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a flowchart showing a basic procedure of a method for measuring the height of a protrusion according to the present invention. As shown in the figure, this measuring method is composed of four stages: an imaging stage in step S1, an outline extraction stage in step S2, a diameter generating line recognition stage in step S3, and a height calculation stage in step S4. Here, the imaging stage of step S1 is a process of performing physical imaging using an imaging camera, whereas the processes of steps S2 to S4 are image processing and arithmetic processing executed by a computer. Hereinafter, the contents of each stage will be described in order.

  First, the imaging stage of step S1 is a stage in which a predetermined area on the work surface including the projection to be measured is imaged from the direction of the elevation angle θ to obtain a planar image including the projection corresponding image. The present invention is a height measurement method for measuring the height of a protrusion formed on a workpiece surface. In this imaging stage, the projection is imaged from a direction that forms an elevation angle θ with respect to the workpiece surface. Become.

  FIG. 2 is a side view showing the concept of this imaging stage. For the sake of convenience, the figure shows a state in which a total of seven protrusions 110 are formed on the upper surface of the workpiece 100. However, in an actual circuit board, BGA, or the like, a larger number of protrusions (bumps) are two-dimensionally shown. Will be placed. An imaging camera 200 capable of imaging a predetermined area on the surface of the workpiece 100 from the direction of the elevation angle θ is disposed obliquely above the workpiece 100. A broken line shown in the figure indicates a normal direction set at the center position of the imaging surface of the imaging camera 200, and forms an elevation angle θ with respect to the surface of the workpiece 100. In this way, a planar image including an image corresponding to a protrusion (hereinafter simply referred to as a protrusion-corresponding image) is obtained on the imaging surface of the imaging camera 200.

  FIG. 3 is a plan view showing a planar image captured by the imaging camera 200. Each of the fan-shaped regions shown by hatching in the figure is a protrusion corresponding image 115 corresponding to each protrusion. Usually, the workpiece 100 and the projection 110 are made of different materials, and the surface of the workpiece 100 and the surface of the projection 110 have different colors and gradations. Therefore, the projection corresponding image 115 on the planar image shown in FIG. Can be identified. FIG. 3 shows an example in which a total of 12 protrusion-corresponding images 115 exist as independent fan-shaped regions in the field of view of the imaging camera 200.

  In practicing the present invention, it is preferable to provide a lower limit and an upper limit for the elevation angle θ shown in FIG. The lower limit value θ1 of the elevation angle θ is defined as a critical angle at which the plurality of projection corresponding images 115 overlap each other when the plurality of projections 110 exist on the surface of the workpiece 100. FIG. 4 is a side view showing the lower limit value θ1. As shown in the figure, for a pair of adjacent protrusions 110a and 110b, the angle between the broken line connecting the contour position of the bottom surface of the protrusion 110a and the vertex position of the protrusion 110b and the surface of the workpiece 100 corresponds to the lower limit value θ1. If the elevation angle θ at the imaging stage is less than this, the corresponding image of the protrusion 110a and the corresponding image of the protrusion 110b are overlapped, so that the individual protrusion corresponding image 115 cannot be recognized as an individual area.

  Of course, even if there are overlaps in the plurality of projection corresponding images 115, the contours of the individual projection corresponding images 115 are extracted by performing processing based on a predetermined algorithm in the contour line extraction step in step S2. However, in order to reduce the calculation processing burden, it is preferable that each projection corresponding image 115 is an independent area as shown in FIG. 3 in the imaging stage. The lower limit value θ1 of the elevation angle θ is a lower limit value set for this reason.

  On the other hand, the upper limit value θ2 of the elevation angle θ is defined as an angle formed by the cone bus forming the protrusion 110 and the surface of the workpiece 100 when each protrusion 110 is assumed to be a cone. FIG. 5 is a side view showing the upper limit value θ2. When the elevation angle θ at the imaging stage is larger than this, the apex portion of the protrusion 110 is buried in the protrusion corresponding image 115, and the point corresponding to the apex position of the protrusion 110 cannot be recognized from the protrusion corresponding image 115. End up. In other words, if the elevation angle θ is less than or equal to this upper limit value, a point corresponding to the apex position of the protrusion 110 appears on the contour line of the protrusion corresponding image 115, which can be recognized. As will be described later, the point corresponding to the vertex position of the protrusion 110 plays an important role in recognizing the busbar corresponding part. In the case of the example shown in FIG. 3, the point corresponding to the vertex position of the protrusion 110 can be recognized as a fan-shaped cusp for any protrusion corresponding image 115.

  Eventually, the elevation angle θ at the imaging stage of step S1 may be set in a range of θ1 <θ <θ2. From the viewpoint of improving measurement accuracy, it is preferable to set the elevation angle θ as small as possible. This is because as the elevation angle θ is reduced, the projection corresponding image 115 becomes elongated, the bus line corresponding portion becomes longer, and the resolution is improved. However, the actual elevation angle θ may be set to an optimum value in a range of θ1 <θ <θ2 in consideration of the size, shape, density of the projection 110 to be measured and the physical arrangement of the imaging camera.

  The subsequent contour line extraction step of step S2 is a step of executing a process of extracting the contour line of the projection corresponding image 115 based on the planar image obtained in the imaging step. Since this processing is actually executed by the computer, the planar image as shown in FIG. 3 obtained at the imaging stage is input to the computer as digital image data.

  As described above, since the surface of the workpiece 100 and the surface of the protrusion 110 are different in color and gradation, the pixel values are different between the internal portion of the protrusion corresponding image 115 and the external portion on the planar image shown in FIG. Differences will occur in the characteristics. Further, even when the color and gradation of the surface of the workpiece 100 and the surface of the protrusion 110 are similar, a shadow is generated in the contour portion of the protrusion 110, so that the pixel value is also characterized in the contour portion. Differences occur. Therefore, in this contour line extraction stage, a method can be adopted in which the planar image obtained in the imaging stage is binarized and a portion where the pixel value changes is recognized as a boundary line. Alternatively, as another method, it is also possible to take a method of differentiating a planar image obtained at the imaging stage and recognizing a portion where the pixel value has a maximum value as a boundary line. Of course, the contour line extraction method is not limited to these methods, and other methods may be used.

  FIG. 6 is a plan view showing a state in which the contour extraction process is performed on one protrusion-corresponding image 115. In the illustrated example, three contour lines C1, C2, and C3 are extracted from the protrusion corresponding image 115, and as a result, three points Q0, Q1, and Q2 are recognized. In the contour line extraction stage of step S2, the contour lines are extracted for each projection corresponding image 115 on the planar image as shown in FIG. In this way, the process of recognizing the position, shape, size, etc. of a plurality of objects existing on the image and making each identifiable with a unique code is generally known as a labeling process. It is processing. Therefore, a description of a specific algorithm for recognizing the contour lines of the individual protrusion correspondence images 115 in this contour line extraction step is omitted here.

  Next, in the diameter generating line recognition stage of step S3, each projection is determined based on the contour line information extracted in the above-described outline extraction stage under the assumption that the projection 110 to be measured has a conical shape. Recognize the “part corresponding to the bottom diameter part of the protrusion 110” on the corresponding image 115 as the diameter corresponding part, and recognize the “part corresponding to the bus part of the protrusion” on the protrusion corresponding image 115 as the bus corresponding part. Processing for obtaining the length D of the diameter corresponding portion and the length L of the bus corresponding portion is executed. Of course, this processing is also actually executed as a computer processing.

  In addition, since the measurement method in the present invention is based on the assumption that the projection to be measured has a conical shape, hereinafter, it is assumed that the projection 110 formed on the workpiece 100 has a complete cone shape. The explanation will be continued below.

  FIG. 7 is a plan view showing a concept of recognition processing performed in the diameter bus bar recognition stage. The illustrated fan shape is the same figure as the protrusion corresponding image 115 shown in FIG. Here, if the projection 110 is a complete cone, the contour lines C1 and C2 correspond to the generatrix of the cone, and the contour line C3 corresponds to the circumferential portion of the bottom surface of the cone. Therefore, the line segment 116 connecting the points Q1 and Q2 on the contour line in the figure is a “portion corresponding to the bottom diameter portion of the protrusion 110” (hereinafter referred to as the diameter corresponding portion 116). A line segment 117 passing through the midpoint Q3 of the line segment 116 and connecting the point Q4 on the contour line C3 and the point Q4 on the contour line C3 corresponds to a conical generatrix like the contour lines C1 and C2. That is, the line segment 117 connecting the points Q0 and Q4 is a “portion corresponding to the busbar portion of the protrusion” (hereinafter referred to as a busbar corresponding portion 117).

  In the diameter generatrix recognition stage of step S3, a process for recognizing the diameter corresponding part 116 and the generatrix corresponding part 117 for each projection corresponding image 115 and obtaining the lengths D and L is executed. However, the process for obtaining the lengths D and L can be performed by a relatively simple process. That is, in practice, the maximum width in the horizontal direction of the protrusion corresponding image 115 may be recognized as the length D of the diameter corresponding portion, and the maximum width in the vertical direction may be recognized as the length L of the busbar corresponding portion.

  At the imaging stage, as shown in FIG. 2, if the imaging camera 200 is installed in the direction of the elevation angle θ and the image of the protrusion 110 is captured (in other words, all the parts in the field of view are directed toward the elevation angle θ). As shown in FIG. 7, the maximum horizontal width of the projection corresponding image 115 is the length D of the diameter corresponding portion, and the maximum vertical width is the length of the bus corresponding portion, as shown in FIG. L. Therefore, if the contour lines C1, C2, and C3 are extracted by the contour extraction step and the protrusion corresponding image 115 is in a state that can be recognized as a closed region, it is necessary to recognize the points Q0, Q1, Q2, and Q4. If the maximum width in the horizontal direction and the maximum width in the vertical direction of the closed region are obtained, the length D of the diameter corresponding portion and the length L of the bus corresponding portion can be obtained.

  In practice, it is necessary to recognize the positions of the large number of protrusion corresponding images 115 together. For example, the cusp Q0 or the like may be recognized as a feature point and processing for recognizing the position coordinate may be performed. Eventually, as in the example shown in FIG. 3, when a planar image having a total of 12 protrusion corresponding images 115 is obtained, each of the 12 protrusion corresponding images 115 has a feature point such as a cusp Q0. The coordinate value (x, y), the length D of the diameter corresponding portion, and the length L of the bus corresponding portion are obtained.

  Finally, in the height calculation stage of step S4, a calculation for obtaining the height h of the protrusion 110 is executed based on the elevation angle θ during imaging in the imaging stage and the lengths D and L obtained in the diameter generatrix recognition stage. The The length D of the diameter-corresponding portion 116 shown in FIG. 7 is equal to the diameter of the bottom surface of the actual protrusion 110, but the length L of the bus-bar corresponding portion 117 depends on the elevation angle θ. It should not be equal to the length. FIG. 8 is a side view showing the principle of calculation considering such points.

  As described above, at the imaging stage, the imaging camera 200 is installed in the direction of the elevation angle θ and an image of the protrusion 110 is captured. This is synonymous with defining a projection plane 210 that intersects the surface of the workpiece 100 at an angle (90 ° −θ) and forming a projection image of the protrusion 110 on the projection plane 210. Therefore, the planar image shown in FIG. 3 corresponds to a projection image formed on the projection surface 210. Therefore, with reference to FIG. 8, the geometric relationship between the length D of the diameter corresponding portion and the length L of the bus corresponding portion obtained in the diameter bus recognition stage and the actual height h of the protrusion 110 is shown. Let's think about it.

  First, as shown in the figure, the length L of the bus bar corresponding part is considered divided into two sections a and b. Of course, L = a + b. Here, the relationship between a and h is a = h cos θ. Further, if the radius of the circle constituting the bottom surface of the actual protrusion 110 is r, b = rsin θ. Since the length D of the diameter corresponding portion is equal to the diameter of the actual protrusion 110, r = D / 2. Therefore, since an equation L = hcos θ + D / 2 · sin θ is derived, by arranging this, an equation h = (LD−2 · sin θ) / cos θ is obtained. After all, in the height calculation stage, h = (L) based on the length D of the diameter corresponding part and the length L of the bus bar corresponding part obtained for each projection corresponding image 115 and the elevation angle θ in the photographing stage. The height h of each protrusion 110 can be obtained by the equation −D / 2 · sin θ) / cos θ.

  FIG. 9 is a block diagram showing a basic configuration of a measuring apparatus that measures the height of the protrusion based on the principle as described above. As shown in the figure, this measuring apparatus includes an imaging camera 310, a scanning unit 320, an illumination unit 330, and a control processing device 340.

  Here, the imaging camera 310 is a camera having a function of imaging an imaging target region on the surface of the workpiece 100 from the direction of the elevation angle θ, and corresponds to the imaging camera 200 shown in FIG. The scanning unit 320 has a function of scanning the imaging camera 310 so that the imaging target area of the imaging camera 310 moves on the surface of the workpiece 100.

  The scanning unit 320 is not essential on the principle of the present invention. That is, even if the imaging camera 310 is not scanned, it is possible to obtain the height of the projection corresponding image 115 obtained in the field of view (imaging target region). Therefore, for example, when a total of 12 protrusion corresponding images 115 are obtained in the field of view as in the example shown in FIG. 3, it is possible to measure the height of 12 protrusions. However, practically, it is preferable that the imaging unit 310 can be scanned by the scanning unit 320 so that measurement can be performed on a region wider than the field of view of the imaging camera 310.

  The illumination unit 330 is a component for illuminating the imaging target area. Of course, if measurement is performed using natural light or the like, the present invention can be implemented without providing the illumination unit 330, but in practice, imaging can be performed in the best illumination environment. Thus, it is preferable to provide the illumination unit 330. In particular, it is desirable that the illumination target area of the illumination unit 330 be moved in accordance with the scanning of the scanning unit 320.

  The control processing device 340 is a component having a function of controlling the imaging camera 310, the scanning unit 320, and the illumination unit 330 and executing processing necessary for measurement. In practice, a predetermined program is incorporated in the computer. Is realized. As shown in the figure, the control processing device 340 has four functions of imaging processing, contour extraction processing, diameter bus recognition processing, and height calculation processing.

  Here, the imaging process is a process for executing the imaging stage of step S1 in the flowchart of FIG. 1. Specifically, the imaging process is performed by controlling the imaging camera 310, the scanning unit 320, and the illumination unit 330. This is a process of capturing a planar image including the protrusion corresponding image 115 for the protrusion 110 to be.

  The contour line extraction process is a process for executing the contour line extraction step of step S2, and an operation of extracting the contour line of the protrusion corresponding image 115 is performed based on the planar image obtained by the imaging process. Specifically, as described above, the planar image obtained by the imaging process is binarized and an operation of recognizing a portion where the pixel value changes as a boundary line is performed.

  The diameter generatrix recognition process is a process for executing the diameter generatrix recognition step in step S3, and assumes that the protrusion 110 to be measured is conical, based on the information on the contour line. This is a process of recognizing the diameter corresponding portion and the bus corresponding portion on the image 115 and obtaining the lengths D and L. Actually, the maximum horizontal width of the protrusion corresponding image 115 is recognized as the length D of the diameter corresponding portion, and the maximum vertical width of the protrusion corresponding image 115 is recognized as the length L of the bus corresponding portion. This is as already described. In practice, the position coordinates of a predetermined feature point are also recognized for each protrusion-corresponding image 115.

  The final height calculation process is a process for executing the height calculation step of step S4, and based on the elevation angle θ, the length D of the diameter corresponding part, and the length L of the bus bar corresponding part, This is a process for obtaining the height h. Specifically, as described above, the height h is obtained from the equation h = (LD / 2 · sin θ) / cos θ.

  By the way, as a specific method of performing imaging for obtaining a projection image of the protrusion 110 on the projection surface 210 shown in FIG. 8, there are a method using an area sensor and a method using a line sensor. When an area sensor is used, imaging may be performed using an area sensor in which imaging pixels are two-dimensionally arranged on the projection plane 210. In other words, imaging may be performed by the imaging camera 310 provided with an area sensor whose imaging surface matches the projection surface 210.

  On the other hand, when a line sensor is used, a line sensor is prepared by arranging pixels one-dimensionally on the projection plane 210 shown in FIG. 8, and imaging is performed by moving the line sensor along the projection plane 210. You can do it.

  Specifically, for example, a line sensor is prepared in which a vertical line perpendicular to the paper surface is set at the position of point P1 in FIG. 8 and imaging pixels are arranged one-dimensionally on the vertical line. When this line sensor is at the position of the point P1 in the figure, only the vicinity of the apex of the protrusion 110 can be imaged, but this line sensor is moved along the projection plane 210 from the position of the point P1 to the position of the point P2. If moved, the projection 110 can be scanned from the apex to the bottom.

  FIG. 10 is a perspective view of an embodiment in which a camera having a line sensor is used as the imaging camera 310. The relative position between the imaging camera 310 and the workpiece 100 can be changed by the moving stage 321, the Y-axis direction scanning unit 322, and the X-axis direction scanning unit 323. The Y-axis direction scanning unit 322 is a component for moving the moving stage 321 in the Y-axis direction in the drawing, and the X-axis direction scanning unit 323 is a configuration for moving the imaging camera 310 in the X-axis direction in the drawing. Is an element. If the workpiece 100 is placed and fixed on the moving stage 321, the imaging camera 310 can be scanned with respect to the workpiece 100 in the X-axis direction (main scanning direction) by the X-axis direction scanning unit 323, and the Y-axis By the direction scanning unit 322, the imaging camera 310 can scan the workpiece 100 in the Y-axis direction (sub-scanning direction). After all, the moving stage 321, the Y-axis direction scanning unit 322, and the X-axis direction scanning unit 323 shown in FIG. 10 function as the scanning unit 320 in the block diagram of FIG.

  A line segment indicated by a symbol E on the workpiece 100 indicates a visual field region of the line sensor in the imaging camera 310. By performing the above-described main scanning and sub-scanning, the visual field region E can be moved to the entire region of the workpiece 100, and the entire surface of the workpiece 100 can be scanned. In addition, an illumination unit 330 is attached to the imaging camera 310. The illumination unit 330 moves together with the imaging camera 310, and is always arranged to illuminate the visual field region E. The specific configuration of the illumination unit 330 is preferably a line illumination, a ring illumination, a dome illumination, or the like in which the projection 110 is less likely to be shaded and the contrast between the surface of the workpiece 100 and the projection 110 can be obtained. It is desirable that the orientation of the imaging camera 310 can be adjusted as necessary, and the elevation angle θ during imaging can be adjusted to an optimum value according to the workpiece 100.

  The control processing device 340 is the same component as that shown in the block diagram of FIG. 9, and is a computer that controls the scanning and executes necessary calculations and processing. This computer incorporates a program for executing each process described above.

  By the way, in the embodiment shown in FIG. 10, imaging is performed based on a principle slightly different from the principle shown in FIG. That is, in order to capture an image using the principle shown in FIG. 8 using the line sensor, it is necessary to move the line sensor along the projection plane 210 from the point P1 to the point P2, as described above. However, the measuring apparatus shown in FIG. 10 only includes a mechanism for moving the imaging camera 310 incorporating the line sensor relative to the workpiece 100 in the X-axis direction and the Y-axis direction. There is no mechanism for moving along the projection plane 210 shown in FIG. Of course, it is possible to provide a mechanism for moving along the projection plane 210, but in reality, such a mechanism becomes quite complicated and is not very practical.

  After all, in the case of the measuring apparatus shown in FIG. 10, the imaging camera 310 has only a function of moving along a plane (XY plane) parallel to the surface of the workpiece 100 as shown in the side view of FIG. There will be no. However, the imaging direction is directed obliquely downward as indicated by a broken line in the figure, and the line-shaped visual field region E is imaged in a direction having an elevation angle θ while being illuminated by the illumination unit 330 positioned above. Will be.

  FIG. 12 is a side view showing the principle of calculation for obtaining the height h of the protrusion 110 when imaging is performed by the measuring apparatus shown in FIG. The projection plane 210 shown in FIG. 12 corresponds to the projection plane 210 shown in FIG. 8, but was obtained by scanning the imaging camera 310 in the X-axis direction and the Y-axis direction in the measurement apparatus shown in FIG. The planar image is not a projection image on the projection plane 210 but a projection image on the projection plane 220 that is a plane parallel to the surface of the workpiece 100. In other words, the line sensor built in the imaging camera 310 has a configuration in which imaging pixels are arranged one-dimensionally on the projection plane 220, and the line sensor is Y along the projection plane 220. It is moved in the axial direction and the X-axis direction (direction perpendicular to the paper surface of FIG. 12).

  For example, a line sensor is prepared in which a vertical line segment perpendicular to the paper surface is set at the position of point P1 in FIG. 12, and pixels are one-dimensionally arranged on the vertical line segment. When this line sensor is at the position of the point P1 in the figure, only the vicinity of the apex of the protrusion 110 can be imaged, but this line sensor is moved along the projection plane 220 from the position of the point P1 to the position of the point P3. If moved, the projection 110 can be scanned from the apex to the bottom. The measuring apparatus shown in FIG. 10 scans the line sensor in the imaging camera 310 based on such a principle.

  The projection corresponding image 115 captured by scanning the line sensor based on such a principle is a projection image obtained by projecting the projection 110 onto the projection plane 220 in the direction of the elevation angle θ. Become. Incidentally, the projection image obtained on the projection plane 220 by such scanning of the line sensor is different from the projection image obtained by the area sensor using the projection plane 220 as the imaging plane. This is because the latter is an image obtained by projecting the projection 110 on the workpiece 100 vertically upward, whereas the former is an image obtained by projecting the projection 110 on the workpiece 100 in the elevation angle θ direction. This is because.

  Eventually, the length L of the bus bar corresponding part of the projection corresponding image 115 imaged by the apparatus shown in FIG. 10 is the distance between the points P1 to P3 on the projection plane 220 shown in FIG. As described above, when imaging is performed according to the principle shown in FIG. 8, the length L of the busbar corresponding portion is the distance between the points P1 and P2 on the projection plane 210, whereas imaging is performed according to the principle shown in FIG. In this case, it should be noted that the length L of the bus bar corresponding portion is the distance between the points P1 to P3 on the projection plane 220. 8 is that the projection 110 is projected on the projection plane 210 in the imaging based on the principle shown in FIG. 8, whereas the projection 110 is projected on the projection plane 220 in the imaging based on the principle shown in FIG. Is a matter of course.

  Therefore, in the apparatus shown in FIG. 10, it is necessary to slightly change the formula used for the height calculation process. In FIG. 12, the distance LL between the points P1 and P2 corresponds to the distance L in FIG. 8, and therefore the variable L in the above-described equation h = (LD / 2 · sin θ) / cos θ is replaced with the variable LL. Thus, in FIG. 12, the equation h = (LL−D / 2 · sin θ) / cos θ is established. Here, as apparent from the figure, since LL = L · sin θ, h = (L · sin θ−D / 2 · sin θ) / cos θ, and this can be summarized as h = (L−D / 2) · The expression tanθ is derived. After all, like the apparatus shown in FIG. 10, it is configured by imaging pixels that are arranged in one dimension so as to be parallel to the surface of the workpiece 100 and that can image the projection 110 from the direction of the elevation angle θ. In the case of a measuring apparatus of a type having a line sensor and scanning the line sensor along a projection plane 220 parallel to the surface of the workpiece 100, the equation h = (L−D / 2) · tan θ is given by The height h of the protrusion 100 may be calculated.

  When scanning is performed using a line sensor or imaging is performed using an area sensor, the obtained planar image constitutes image data composed of a two-dimensional array of pixels, and the length D of the diameter corresponding portion or the like. The length L of the bus bar corresponding portion is obtained as the number of pixels, not the actual size. In order to convert the number of pixels to the actual size, an operation of multiplying the pitch of the pixel array may be performed. Here, the pitch of the pixel array is determined by the vertical and horizontal widths of the imaging pixels constituting the sensor to be used. For example, in the case of a line sensor as shown in FIG. 13, the horizontal dimension is m (dimension in the X-axis direction) and the vertical dimension is n (dimension in the Y-axis direction). Is moved in pitch n units. Therefore, the horizontal pitch (X-axis direction pitch) of the pixel array constituting the obtained image data is m, and the vertical pitch (Y-axis direction pitch) is n. For this reason, the actual size of the interval in which the number of pixels in the horizontal direction is x pixels is obtained as m × x, and the actual size in the interval in which the number of pixels in the vertical direction is y pixels is obtained as n × y. The same applies to the area sensor.

  Eventually, a projection projection image consisting of a two-dimensional array of pixels having a size of m × n is obtained on the projection plane, where m is the horizontal width of the imaging pixels constituting the sensor and n is the vertical width. In this case, if the number x of pixels corresponding to the maximum width in the horizontal direction and the number y of pixels corresponding to the maximum width in the vertical direction are counted, the length D of the diameter corresponding portion is D = m × x The length L of the bus bar corresponding part is obtained by the calculation of L = n × y. Of course, when an optical system is arranged in front of the sensor and the image is optically enlarged or reduced during imaging, it is necessary to perform correction by multiplying the magnification.

  As mentioned above, although this invention was demonstrated based on the Example shown in figure, this invention is not limited to these Examples, In addition, it can implement in a various aspect. For example, in the above-described embodiment, the scanning unit 320 performs scanning by moving the imaging camera 310. However, moving the imaging camera 310 relative to the workpiece 100 causes the workpiece 100 to move relative to the imaging camera 310. Is equivalent to moving. Therefore, instead of moving the imaging camera 310, scanning may be performed by moving the workpiece 100 side.

  The basic principle of the present invention is based on the assumption that the projection to be measured has a conical shape. However, in practice, the measurement is not necessarily limited to the measurement with respect to the conical projection. For example, when the protrusion shape is a quadrangular pyramid, the same technique as described above can be applied if imaging is performed from the front direction of the quadrangular pyramid. In addition, the measurement method of the present invention can be applied to a hemispherical protrusion or the like as long as a certain amount of error can be allowed. In this case as well, the height h may be obtained by applying the above formula where D is the maximum horizontal width of the projection corresponding image and L is the maximum vertical width.

It is a flowchart which shows the basic procedure of the protrusion height measuring method which concerns on this invention. It is a side view which shows the concept of the imaging stage in the measuring method which concerns on this invention. It is a top view which shows an example of the plane image imaged with the imaging camera 200 shown in FIG. FIG. 3 is a side view showing a lower limit value θ1 of an elevation angle θ in the imaging stage shown in FIG. FIG. 3 is a side view showing an upper limit value θ2 of an elevation angle θ in the imaging stage shown in FIG. It is a top view which shows the state which performed the outline extraction process about one protrusion corresponding | compatible image 115. FIG. It is a top view which shows the concept which recognizes a diameter corresponding | compatible part and a bus-line corresponding | compatible part about one protrusion corresponding | compatible image 115. FIG. It is a side view which shows the principle of the calculation which calculates | requires the height h of the processus | protrusion 110 based on the elevation angle (theta) at the time of imaging in an imaging stage, and the lengths D and L obtained at the diameter generating line recognition stage. It is a block diagram which shows the basic composition of the protrusion height measuring apparatus which concerns on this invention. It is a perspective view which shows the structure of the specific Example of the protrusion height measuring apparatus which concerns on this invention. It is a side view which shows the scanning state of the imaging camera 310 in the measuring apparatus shown in FIG. FIG. 11 is a side view showing the principle of calculation for obtaining the height h of the protrusion 110 based on the elevation angle θ at the time of imaging and the lengths D and L obtained at the diameter generatrix recognition stage in the measuring apparatus shown in FIG. 10. It is a top view which shows the pixel pitch of a general line sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Work 110 ... Protrusion 110a, 110b ... Protrusion 115 ... Protrusion corresponding | corresponding image 116 ... Diameter corresponding | compatible part 117 ... Bus-line corresponding | compatible part 200 ... Imaging camera 310 ... Imaging camera 320 ... Scanning part 321 ... Moving stage 322 ... Y-axis direction scanning means 323 ... X-axis direction scanning means 330 ... illumination part 340 ... control processing devices C1 to C3 ... contour line D ... diameter corresponding part length E ... field of view h ... projection height L ... bus corresponding part length m ... line The width n of the pixels constituting the sensor, the vertical widths P1 to P3 of the pixels constituting the line sensor, the geometric points Q0 to Q4, the points r on the projection corresponding image, and the radii S1 to S4 of the cone. θ: Elevation angle θ1 during imaging: Lower limit value of elevation angle θ2: Upper limit value of elevation angle θ

Claims (16)

A method for measuring the height of a protrusion formed on a workpiece surface,
An imaging stage for capturing a predetermined area on the workpiece surface including the projection to be measured from the direction of the elevation angle θ and obtaining a planar image including the projection corresponding image;
An outline extraction step for causing a computer to execute a process of extracting an outline of the projection corresponding image based on the planar image obtained in the imaging step;
Under the assumption that the projection to be measured is a conical shape, a portion corresponding to the bottom diameter portion of the projection on the projection corresponding image is determined as a diameter corresponding portion on the projection correspondence image based on the information on the contour line. And recognizing the portion corresponding to the generatrix portion of the protrusion on the image corresponding to the protrusion as a busbar corresponding portion, and executing the process of obtaining the length D of the diameter corresponding portion and the length L of the busbar corresponding portion. A diameter generating line recognition stage,
A height calculating step for causing the computer to execute a process of calculating a height h of the protrusion based on the elevation angle θ, the length D of the diameter corresponding portion, and the length L of the bus corresponding portion;
A method for measuring the height of a protrusion, characterized by comprising: In the method for measuring the height of the protrusion according to claim 1,
When there are a plurality of protrusions on the work surface, the critical angle of the elevation angle θ at which the plurality of protrusion corresponding images overlap each other at the imaging stage is defined as θ1, and the angle formed between the conical bus forming the protrusion and the work surface A method for measuring the height of a protrusion, characterized in that the elevation angle θ at the imaging stage is set in a range of θ1 <θ <θ2, where is θ2. In the method for measuring the height of the protrusion according to claim 1 or 2,
In the contour extraction stage, the planar image obtained in the imaging stage is binarized, and the part where the pixel value changes is recognized as a boundary line, or the planar image obtained in the imaging stage is differentiated, A method for measuring the height of a protrusion, wherein a portion having a maximum pixel value is recognized as a boundary line. In the method for measuring the height of the protrusion according to any one of claims 1 to 3,
In the diameter generatrix recognition stage, the lateral maximum width of the protrusion corresponding image is recognized as the length D of the diameter corresponding portion, and the vertical maximum width of the protrusion corresponding image is recognized as the length L of the bus corresponding portion. A method for measuring the height of protrusions. In the method for measuring the height of the protrusion according to any one of claims 1 to 4,
When there are a plurality of protrusions on the workpiece surface, in the diameter generatrix recognition stage, the lengths D and L for each protrusion corresponding image are recognized, and the position coordinates for a predetermined feature point are recognized, A method for measuring the height of a protrusion, wherein the position and height of each protrusion are measured. In the method for measuring the height of the protrusion according to any one of claims 1 to 5,
At the imaging stage, a projection corresponding image is obtained on a projection plane that intersects the workpiece surface at an angle (90 ° -θ),
A method for measuring the height of a protrusion, wherein the height h of the protrusion is obtained by using an equation of h = (LD / 2 · sin θ) / cos θ in the height calculation stage. In the method for measuring the height of the protrusion according to claim 6,
In the imaging stage, a projection plane that intersects the workpiece surface at an angle (90 ° −θ) is defined, and imaging is performed using an area sensor in which imaging pixels are two-dimensionally arranged on the projection plane. A method for measuring the height of protrusions. In the method for measuring the height of the protrusion according to any one of claims 1 to 5,
At the imaging stage, a projection corresponding image is obtained by projecting the projection in the direction of the elevation angle θ on the projection plane parallel to the workpiece surface,
A method for measuring the height of a protrusion, wherein the height h of the protrusion is obtained by using the formula h = (LD / 2) · tan θ in the height calculation stage. In the method for measuring the height of the protrusion according to claim 8,
At the imaging stage, a projection plane parallel to the workpiece surface is defined, a line sensor is prepared by arranging pixels one-dimensionally on the projection plane, and the line sensor or workpiece is moved along the projection plane. A method for measuring the height of a protrusion, characterized in that imaging is performed. A measuring device for measuring the height of a protrusion formed on a workpiece surface,
An imaging camera for imaging an imaging target area on the workpiece surface from the direction of the elevation angle θ;
A scanning unit that scans the imaging camera so that the imaging target region moves on the workpiece surface;
An illumination unit for illuminating the imaging target area;
A control processing device that controls the imaging camera, the scanning unit, and the illumination unit, and executes processing necessary for measurement;
The control processing device comprises:
An imaging process for capturing a planar image including a projection corresponding image of a projection to be measured by controlling the imaging camera, the scanning unit, and the illumination unit;
An outline extraction process for extracting an outline of the projection corresponding image based on the planar image obtained by the imaging process;
Under the assumption that the projection to be measured is conical, based on the information on the contour line, the portion corresponding to the bottom diameter portion of the projection on the projection corresponding image is recognized as the diameter corresponding portion. A diameter busbar recognition process for recognizing a portion corresponding to a busbar portion of the projection on the projection corresponding image as a busbar corresponding portion, and obtaining a length D of the diameter corresponding portion and a length L of the busbar corresponding portion;
A height calculation process for calculating a height h of the protrusion based on the elevation angle θ, the length D of the diameter corresponding portion, and the length L of the busbar corresponding portion;
A projection height measuring device having a function of executing In the projection height measuring device according to claim 10,
In the contour extraction process, the planar image obtained by the imaging process is binarized, and the portion where the pixel value changes is recognized as a boundary line, or the planar image obtained by the imaging stage is differentiated, and the pixel value is A projection height measuring apparatus, which is executed by recognizing a portion having a maximum value as a boundary line. The height measuring apparatus for protrusions according to claim 10 or 11,
Diameter bus recognition processing is executed by recognizing the maximum horizontal width of the protrusion-corresponding image as the length D of the diameter-corresponding portion and recognizing the maximum vertical width of the protrusion-corresponding image as the length L of the busbar-corresponding portion. A projection height measuring device characterized in that: In the projection height measuring device according to any one of claims 10 to 12,
It has the function of recognizing the lengths D and L of the individual protrusion corresponding images, the function of recognizing the position coordinates of the predetermined feature points, and the function of measuring the position and height of each protrusion. Protrusion height measuring device. In the projection height measuring device according to any one of claims 10 to 13,
The imaging camera has an area sensor configured by two-dimensionally arranging imaging pixels on a projection plane that intersects the workpiece surface at an angle (90 ° -θ),
A projection height measuring device, wherein the control processing unit obtains the projection height h using an equation h = (LD / 2 · sin θ) / cos θ. In the projection height measuring device according to any one of claims 10 to 13,
The imaging camera has a line sensor composed of imaging pixels that are arranged in one dimension so as to be parallel to the workpiece surface and that can image the protrusion from the direction of the elevation angle θ.
The scanning unit has a function of scanning the line sensor or the workpiece along a projection plane parallel to the workpiece surface,
A protrusion height measuring device, wherein the control processing device obtains the protrusion height h using an equation h = (L−D / 2) · tan θ. A program for causing a computer to function as the control processor in the height measuring apparatus of the projection according to any one of claims 10 to 15.