JP2004118467A - Member inclination recognizing method, member inclination recognition control program, readable recording medium, and shape recognizing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform much more stable member shape side inclination recognition processing by preventing positional deviation due to the erroneous recognition of the end surface position of a chip shape even when an image is relatively unclear. <P>SOLUTION: A CPU 65 is provided with a point extracting means 651 for extracting n(n is a natural number which is 3 or more) pieces of a plurality of points from each side on the outline shape of a semiconductor chip 2, a primary approximate formula creating means 652 for preparing a primary approximate formula from those n pieces of the plurality of the points, and a primary approximate formula re-creating means 653 for repeating processing to remove the point which is the farthest from the primary approximate formula until the number of remaining points in removing the point which is the farthest from the calculated primary approximate formula is turned to be a predetermined value (n/3 in this case) which is less than n, and for calculating a primary approximate formula from the remaining points again. In this case, inclination (a) of the recreated primary approximate formula Y=aX+b is defined as the inclination of a member shape side (the inclination of the semiconductor chip 2) and the member shape is recognized. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a member inclination recognition method for recognizing the inclination of a member shape such as a semiconductor chip in a semiconductor laser inspection process, a member inclination recognition control program for executing the method, a readable recording medium storing the same, and And an external shape recognizing device such as a semiconductor chip recognizing device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a semiconductor chip recognizing device includes an XYθ stage, a CCD camera optical system, and an illuminating device, and can recognize the inclination of the external shape of a member such as a semiconductor chip.
[0003]
The illuminating device illuminates the semiconductor chip on the XYθ stage with illuminating light, captures a chip outline image of the semiconductor chip with a CCD camera, recognizes the end face position of the chip outline image, and uses the XYθ stage driver to drive the semiconductor chip. The chip is driven to move to a reference position.
[0004]
As one example, Japanese Patent Application Laid-Open No. 6-13417 discloses a "semiconductor chip recognition device".
[0005]
As shown in FIG. 18, the semiconductor chip recognition device first performs a binarization process of processing a chip image signal obtained by imaging a semiconductor chip with a television camera and converting the image signal into a digital signal representing shading ( Step S51).
[0006]
Next, a coordinate point detection process of performing processing on the obtained chip image signal, detecting an edge portion for each side of the semiconductor chip, and detecting coordinate points on the chip image display screen for a plurality of detected edge portions is performed. Perform (Step S52).
[0007]
Further, the degree of unevenness of the edge part is detected by comparing the correlation coefficient of the coordinate point data for each side of the semiconductor chip, and one side having the smallest degree of unevenness of the edge part is determined (step S53).
[0008]
Finally, the inclination of one side obtained in the determination processing of step S53 is obtained by the least squares method (step S54).
[0009]
[Patent Document 1]
JP-A-6-13417
[Problems to be solved by the invention]
The conventional semiconductor chip recognition device described above has a problem in that when the outer shape image of the semiconductor chip is unclear, the end face position of the outer shape of the chip is erroneously recognized.
[0011]
In addition, the instability of illumination and chip surface condition is included as a variation factor in recognition of the end face position of the chip outer shape. To compensate for these, registration of a reference image (chip reference image for each inclination) and a position matching the reference image However, there is a problem that a large amount of time is required for searching and matching processing in the image area for detecting the image.
[0012]
The present invention solves the above-described conventional problem. Even if the image is somewhat unclear, it is possible to prevent misalignment of the end surface position of the chip outer shape due to erroneous recognition and perform more stable inclination recognition of the outer shape side of the member. An object of the present invention is to provide a member inclination recognition method, a member inclination recognition control program for executing the method, a readable recording medium on which the program is recorded, and an outer shape recognition device using the same.
[0013]
[Means for Solving the Problems]
The member inclination recognizing method of the present invention is a member inclination recognizing method for recognizing the inclination of a member shape, wherein n points (n is a natural number of 3 or more) are extracted from the outer side of the member, and a primary order is obtained from the n points. After obtaining the approximate expression, the process excluding the point farthest from the primary approximation formula is repeated until the number of remaining points excluding the point farthest from the primary approximation formula becomes a predetermined value smaller than n. The inclination a of the linear approximation Y = a.X + b obtained again from the remaining points is defined as the inclination of the outer side of the member, thereby achieving the above object. Further, as a corresponding device, the contour recognition device of the present invention is a contour recognition device for recognizing the inclination of a member shape, wherein a point extracting means for extracting a plurality of n points (n is a natural number) from a member contour side. A first-order approximation formula generating means for obtaining a first-order approximation formula from the n points, and a process until the number of remaining points excluding the point farthest from the first-order approximation becomes equal to or less than a predetermined value smaller than n. A primary approximation formula regenerating means for repeating a process for removing a point which is farthest from the primary approximation formula and re-calculating the primary approximation formula from the remaining points, wherein the reconstructed primary approximation formula Y = a × X + b Is recognized as the inclination a of the outer side of the member, thereby achieving the above object.
[0014]
Preferably, in the member inclination recognition method of the present invention, the member is a semiconductor chip, and the predetermined value is n / 3.
[0015]
More preferably, the distance between the first-order approximation formula and the point in the member inclination recognition method of the present invention is Y-Yi (X) (i = 0 to n) when the coordinates of the point are (X, Y). .
[0016]
More preferably, the distance between the first-order approximation formula and the point in the member inclination recognition method of the present invention is represented by the coordinates of the point (X, Y), and the distance between the approximation straight line of the first-order approximation formula and the point √ (ΔX × ΔX + ΔY × ΔY) where ΔX = (X−Xi) and ΔY = (Y−Yi) (i = 0 to n).
[0017]
More preferably, the first-order approximation formula in the member inclination recognition method of the present invention is obtained by previously subtracting 90 ° from a member side inclined by 90 ° with respect to the reference line.
[0018]
Still preferably, in a member inclination recognition method according to the present invention, one side of a member outer side is divided into a plurality of regions, and the inclination of the member outer side is obtained based on a linear approximation formula calculated for each of the divided regions.
[0019]
More preferably, in the member inclination recognition method of the present invention, a first-order approximation formula is calculated for all the member sides, and the inclination of the outer shape side of the member is obtained based on the calculated first-order approximation expression.
[0020]
Still preferably, in the member inclination recognizing method of the present invention, a binarized threshold level at which a dimension of a member outline when recognizing a member outline side is closest to a predetermined dimension is set, and the member outline side inclination recognition process is performed. This is performed at the binarized image or the focal position of the camera.
[0021]
Still preferably, in the member inclination recognizing method of the present invention, the member outer side inclination recognition processing is performed on a chip sheet.
[0022]
Still preferably, in the member inclination recognizing method of the present invention, the member outer side inclination recognizing process is performed during conveyance from the chip sheet to the die bonding position.
[0023]
A member inclination recognition control program according to the present invention causes a computer to execute each processing procedure of the member outline inclination recognition method according to any one of claims 1 to 10, thereby achieving the above object.
[0024]
The readable recording medium of the present invention is readable by a computer in which the member inclination recognition control program according to claim 11 is recorded, thereby achieving the above object.
[0025]
The operation of the present invention having the above configuration will be described below.
[0026]
In the present invention, for example, n coordinate points are extracted from a contour side of a contour of a semiconductor chip as a recognition target member, and a first-order approximation formula is obtained therefrom, and then a coordinate point farthest from the first-order approximation formula is determined. If the remaining coordinate points are equal to or more than a predetermined value of, for example, n / 3, the above process is repeated, and if the remaining points are a predetermined value (a predetermined number value) (or the slope change becomes equal to or less than the predetermined slope value). Up to that point), the inclination of the first-order approximation formula Y (X) at that time is defined as the inclination of the outer side of the semiconductor chip. Therefore, it is possible to prevent erroneous recognition due to the variation of the outline image data on the member outline, and to achieve a more stable inclination. Measurement and processing time can be reduced.
[0027]
Further, the distance between the approximate expression and the point is obtained by extracting a point apart from the approximate expression by setting Y-Yi (X) (i = 0 to n) when the coordinates of the point are (X, Y). Becomes possible.
[0028]
Further, when the coordinates of the point are (X, Y), the distance between the approximate expression and the point is √ (ΔX × ΔX + ΔY × ΔY), ΔX = (X−Xi), ΔY = (Y−Yi) (i = 0 to n), it is possible to accurately extract points away from the approximate expression.
[0029]
Further, since the predetermined value is n / 3, it is possible to remove variation in tilt recognition and improve measurement accuracy.
[0030]
Furthermore, if 90 ° is subtracted in advance for a side inclined by 90 ° with respect to the reference line, it is possible to calculate the inclination angle with respect to the end face to be always measured.
[0031]
Further, if the processes of claims 1 to 5 are performed for a plurality of portions on one side, it is possible to suppress the variation in the inclination of the portion within each side.
[0032]
Further, if the processing of claims 1 to 5 is performed for a plurality of sides, it is possible to suppress the variation in the inclination of each side.
[0033]
Further, when the outer shape side of the member is recognized, for example, at a binarization level (or the focal position of the camera) where the size of the semiconductor chip is closest to the predetermined size, the recognition deviation of the chip end face can be further prevented.
[0034]
Further, if the above-described member outer side inclination recognition processing is performed on the chip sheet, the positioning step can be omitted, and the time can be further reduced.
[0035]
Furthermore, if the above-described process of recognizing the inclination of the outer shape of the member is performed during the transportation from the chip sheet to the die bonding position, the time can be reduced.
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a case in which an embodiment of the outer shape recognition device of the present invention is applied to a semiconductor chip recognition device will be described with reference to the drawings.
[0037]
FIG. 1 is a block diagram showing a main configuration of an embodiment of the semiconductor chip recognition device of the present invention.
[0038]
In FIG. 1, a semiconductor chip recognizing device 1 includes an XYθ stage 3 on which a semiconductor chip 2 is installed and whose X-axis, Y-axis and angle θ can be corrected, an illumination device 4 for irradiating the semiconductor chip 2 with light, and a semiconductor device. It has a camera device 5 such as a CCD camera for picking up an image of the chip 2 and an image calculation unit 6 for performing image recognition processing of a chip image picked up by the camera device 5, and recognizes the inclination of the member shape of the semiconductor chip 2. .
[0039]
The image calculation unit 6 includes a ROM 61 serving as a storage unit (for example, a readable recording medium such as an optical disk and a magnetic disk) in which a chip inclination recognition control program and various data thereof are recorded, and stores data when starting the chip inclination recognition control program. A RAM 62 serving as a temporary storage unit serving as a work memory for temporarily storing, and a liquid crystal display device capable of displaying various screens such as an image processing result screen in addition to an initial screen, a chip image screen, an end screen, and various selection screens. The display unit 63 includes an input unit 64 such as a keyboard and a mouse for performing a user input operation, and a CPU 65 (central processing unit) as a control unit for controlling each unit.
[0040]
The CPU 65 controls the entire chip inclination recognition control process of the present invention based on the chip inclination recognition control program and various data thereof. That is, the CPU 65 extracts n (n is a natural number of 3 or more) plural points from each side on the outline of the semiconductor chip 2, and obtains a first-order approximation expression from the n plural points. The first-order approximation formula generating means 652 to be obtained and the first-order approximation formula generation unit 652 perform the first-order approximation until the number of remaining points excluding the point farthest from the first-order approximation formula becomes equal to or less than a predetermined value smaller than n (here, n / 3). A primary approximation formula regenerating means 653 for repeating the process of removing the point farthest from the approximation formula and re-obtaining the primary approximation formula from the remaining points; The outer shape of the member is recognized as the inclination a of X + b as the inclination of the outer side of the member (the inclination of the semiconductor chip 2).
[0041]
With the above configuration, the operation procedure of the semiconductor chip recognition device 1 of the present invention will be described below.
[0042]
As shown in FIG. 2, in step S <b>1; as a preparatory work for chip image capturing processing, first, a semiconductor chip 2 (hereinafter simply referred to as a chip) is mounted on an XYθ stage 3, and illumination light is applied to the chip 2 by a lighting device 4. Apply moderately. Thereafter, the camera device 5 captures image data of the chip outer shape.
[0043]
Step S2: As the binarization threshold level adjustment processing and the binarization processing of the chip image, as shown in FIG. 3, the binarization threshold level of the captured image data is sequentially lowered from a higher value (or (While increasing the binarization threshold level sequentially from a lower value), the binarization process is performed by determining a binarization level that substantially matches the reference dimension. That is, a binarized threshold level at which a member dimension when recognizing the inclination of the outer side of the chip 2 is closest to a predetermined dimension is set, and this inclination recognition processing is performed on the binarized image (or the focal position of the camera device 5). ).
[0044]
Step S3: As the chip outline extraction processing (chip outline extraction means), first, as shown in FIGS. 4A and 4B, the outline outline of the chip 2 is obtained from the binarized image obtained in Step S2. Is extracted.
[0045]
Step S4: As the inclination calculation processing of each divided area of one side (side partial area inclination calculation means), each of the upper side, the lower side, the left side, and the right side is extracted from the extracted contour data by a plurality of points as shown in FIG. (Here, a total of three places, two places at both ends and one place in the middle for each side), and the slopes of all twelve places totaling all sides are calculated. This inclination calculation is first performed for the four sides around the chip. First, the area of the first side is recognized. As shown in FIG. 6, one side is divided into three partial areas, for example, (1), (2) and (3). As shown in FIG. 7, a first-order approximation formula (approximate straight-line formula) of a partial region (1), which is one of the partial regions on one side, is obtained.
[0046]
Step S5: Except for the data D1 farthest from the linearly approximated straight line A, the linear approximation is again performed to obtain a primary approximate expression. As shown in FIGS. 8A and 8B, the most distant data D1 is a difference 直線 (Δx × Δx) + (Δy ×) from the straight line A of the approximate straight line formula in the Y direction or from the straight line A. Δy) is the largest data and is selected.
[0047]
Step S6: Until the data amount becomes 1/3 of the original data amount, the first-order approximation calculation process of step S5 for performing the first-order approximation operation again except for the data farthest away is repeated.
[0048]
The result of the repeated linear approximation equation is a partial inclination value θ1 within the side (a partial area (1) of one side). The method of finding θ1 is based on the a value of y = a · x + b, and the inclination angle θ1 (deg) = arctan (a). However, 90 (deg) is subtracted from the inclination angles of the left side and the right side.
[0049]
Steps S7 to S9: In the same manner as in the processing of steps S5 to S7, an approximate straight line equation of the partial area (2) is obtained (see FIG. 10), and the data farthest away from the original data amount is reduced to 1/3 of the original data amount. By continuing the primary approximation calculation again, the partial inclination value θ2 of the partial area (2) on one side is similarly obtained.
[0050]
Steps S10 to S12: In the same manner as steps S5 to S7 and S7 to S9, an approximate straight-line equation for the partial area (3) is obtained (see FIG. 11). By continuing to remove the most distant data and performing a first-order approximation operation again, the partial inclination value θ3 of the partial area (3) on one side is similarly obtained.
[0051]
Step S13: Similarly, for the remaining nine partial regions (three regions per side) of the three remaining sides, a series of processes of steps S4 to S12 are repeated until the inclination calculation of the four sides is completed. , And all remaining partial inclination values θ4 to θ12 are obtained.
[0052]
Step S14: Among the calculated 12 inclination angle results θ1 to θ12, the average of four intermediate values excluding 4 from the smallest data and 4 from the largest data is calculated. The average value of the calculated tilt angles is defined as the tilt of the chip 2. The tilt angle θa obtained in this manner is used as a final result.
[0053]
Here, a case will be described in which a linear equation is established for recognition of the measured end face based on the obtained inclination angle θa.
[0054]
As shown in FIG. 12, a linear equation (aX + b) passing through the point (sx, ey) is obtained using the tip tilt angle, and the number of pixels on the straight line of this linear equation is counted.
[0055]
As shown in FIG. 13A, the intercept b of the obtained linear equation is changed, and a linear equation (aX + b-n) passing through the point (sx, ey-n) is sequentially obtained. Count how many overlap.
[0056]
If the count value exceeds 50% of the number of searches as shown in FIG. In this way, a straight line equation that matches the end face of the chip 2 is obtained.
[0057]
As shown in FIG. 14A, an average value of each position on both sides indicated by a cross in FIG. 14B is obtained from both side edge data near the upper and lower centers of both sides of the chip outer shape.
[0058]
As shown in FIG. 15A, a perpendicular line is drawn from the obtained positions (marked by x) on both sides to an approximate straight line A of the end surface position, intersections U and V are set as chip end surface corner positions, and the average position of these two points is calculated. , As shown in FIG. 15B.
[0059]
The correction amount (Xm, Ym, θm) of the XYθ stage 3 is calculated from the tilt angle θa and the rotation center of the XYθ stage 3 based on the amount of movement to the reference position at which the chip end surface is to be moved. The position of the stage 3 is moved for correction.
[0060]
As described above, according to the present embodiment, after extracting n points from the contour of the chip 2 and obtaining their linear approximations, the remaining points (excluding the points farthest from the linear approximations) ( If the number of remaining points excluding the points marked with a cross in FIG. 9 is equal to or more than （(predetermined value) of n, the above process is repeated, and the number of remaining points is reduced to a predetermined value (n is smaller than n). (Small value) or if it is small (or until the change of each slope a of the first-order approximate linear expressions A1 to A4 in FIG. 9 becomes equal to or less than a predetermined slope), then the first-order approximate expression Yn / 3 (X) Is the inclination of the chip 2. For this reason, it is possible to prevent erroneous recognition due to variations in the outer shape image data on the outline (outer side) of the chip 2, and to achieve more stable tilt measurement and a reduction in processing time.
[0061]
In the above embodiment, the semiconductor chip 2 is fixed on the XYθ stage 3 to perform the chip side inclination recognition processing. However, the chip side inclination recognition processing may be performed on a chip sheet as shown in FIG. If performed on the chip sheet, the step of positioning the chip 2 can be omitted, and the time can be further reduced. The chip side inclination recognition process may be performed during the transfer from the chip sheet to the die bonding position as shown in FIG. Also in this case, time can be reduced.
[0062]
【The invention's effect】
As described above, according to the present invention, in the method for recognizing the inclination of the chip shape, particularly the chip shape, in the semiconductor laser inspection process, the chip is illuminated with illumination light, and even when the chip outline image is unclear, the end face of the chip outline The position can be accurately recognized as the outer shape. For this reason, there is no need for complicated processing associated with the time-consuming matching recognition used in the conventional method, and the external shape can be easily and accurately recognized even if it is somewhat unclear. Therefore, there is no misalignment due to erroneous recognition of the end surface position of the chip outer shape, and more stable chip inclination recognition can be performed.
[0063]
Further, since the member outline, that is, the member outline is extracted, image data processing specialized for the peripheral portion of the outline can be performed, and the processing time can be reduced. As described above, the chip inclination recognition processing can be performed by simple and partial recognition processing as compared with the conventional example, and the chip inclination recognition processing can be performed more stably and the processing time can be shortened.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of an embodiment of a semiconductor chip recognition device of the present invention.
FIG. 2 is a flowchart showing an operation procedure of a chip inclination recognition process by the semiconductor chip recognition device of FIG. 1;
FIG. 3 is an explanatory diagram of a binarization calculation method (1) of a captured image in the chip inclination recognition processing of the present invention.
FIGS. 4A and 4B are explanatory diagrams of a method of calculating the inclination of a chip contour side of a captured image (part 1) in the chip inclination recognition processing of the present invention.
FIG. 5 is an explanatory diagram of a binarization calculation method (part 2) of a captured image in the chip inclination recognition processing of the present invention.
FIG. 6 is an explanatory diagram of a method (part 2) of calculating the inclination of a chip contour side of a captured image in the chip inclination recognition processing of the present invention.
FIG. 7 is an explanatory diagram of a method (part 3) of calculating the inclination of a chip contour side of a captured image in the chip inclination recognition processing of the present invention.
FIGS. 8A and 8B are diagrams for explaining the case where the difference between the approximate line A of the captured image and the data in the chip inclination recognition processing of the present invention is Y-Yi.
FIG. 9 is an explanatory diagram of an approximate expression thinning calculation method of the inclination of a captured image in the chip inclination recognition processing of the present invention.
FIG. 10 is an explanatory diagram of a method (part 4) of calculating the inclination of a chip contour side of a captured image in the chip inclination recognition processing of the present invention.
FIG. 11 is an explanatory diagram of a method for calculating the inclination of a chip contour side of a captured image (part 5) in the chip inclination recognition processing of the present invention.
FIG. 12 is an explanatory diagram of an end face position calculation method (part 1) of the chip outer shape recognition processing according to the embodiment of the present invention.
FIGS. 13A and 13B are explanatory diagrams of an end face position calculation method (part 2) of the chip outer shape recognition processing according to the embodiment of the present invention.
FIGS. 14A and 14B are explanatory diagrams of an end face position calculation method (part 3) of the chip outer shape recognition processing according to the embodiment of the present invention.
FIGS. 15 (a) and (b) are explanatory diagrams of an end face position calculating method (part 4) of the chip outer shape recognition processing according to the embodiment of the present invention.
FIG. 16 is a schematic diagram in the case of sheet outline recognition.
FIG. 17 is a schematic diagram in the case of back surface outer shape recognition.
FIG. 18 is a flowchart showing an operation procedure of a chip inclination recognition process by a conventional outer shape recognition device.
[Explanation of symbols]
1 semiconductor chip recognition device (outline recognition device)
2 Semiconductor chip 3 XYθ stage 4 Illumination device 5 Camera device 6 Image operation unit 61 ROM
62 RAM
63 input unit 64 display unit 65 CPU
651 point extracting means 652 first-order approximate expression creating means 653 first-order approximate expression creating means

Claims (13)

In the member inclination recognition method for recognizing the inclination of the member shape,
After extracting n (n is a natural number of 3 or more) points from the outer side of the member, obtaining a first-order approximation expression from the n points, the remaining points are removed except for the point farthest from the first-order approximation expression. Until the number of points becomes equal to or less than a predetermined value smaller than n, the processing of removing the point farthest from the primary approximation formula is repeated, and the gradient of the primary approximation formula Y = a · X + b obtained again from the remaining points A member inclination recognizing method in which a is the inclination of a member outer side. The member inclination recognition method according to claim 1, wherein the member is a semiconductor chip, and the predetermined value is n / 3. The member inclination recognition method according to claim 1, wherein the distance between the first-order approximation formula and the point is Y-Yi (X) (i = 0 to n) when the coordinates of the point are (X, Y). The distance between the first-order approximation formula and the point is represented by (X, Y), the coordinate of the point, the distance between the approximation straight line of the first-order approximation formula and the point √ (ΔX × ΔX + ΔY × ΔY), where ΔX = (X− 2. The member inclination recognition method according to claim 1, wherein Xi), ΔY = (Y−Yi) (i = 0 to n)}. The member inclination recognizing method according to claim 1, wherein the first-order approximation expression is obtained by previously subtracting 90 ° from the member side inclined by 90 ° with respect to a reference line. 2. The member inclination recognition method according to claim 1, wherein one side of the member outer side is divided into a plurality of regions, and the inclination of the member outer side is obtained based on a linear approximation formula calculated for each divided region. The member inclination recognition method according to claim 1, wherein the first-order approximate expression is calculated for all of the member sides, and the inclination of the member outer side is obtained based on the calculated first-order approximate expression. A binarization threshold level at which a dimension of the outer shape of the member when recognizing the outer shape side of the member is closest to a predetermined size is set, and the process of recognizing the inclination of the outer shape of the member is performed on the binarized image or the focal position of the camera. 2. The member inclination recognition method according to 1. The member inclination recognizing method according to claim 1, wherein the member outline side inclination recognition processing is performed on a chip sheet. The member inclination recognition method according to claim 1, wherein the member outline side inclination recognition processing is performed during conveyance from the chip sheet to the die bonding position. A member inclination recognition control program for causing a computer to execute each processing procedure of the member outline inclination recognition method according to any one of claims 1 to 10. A computer-readable recording medium on which the member inclination recognition control program according to claim 11 is recorded. In the outline recognition device that recognizes the inclination of the member shape,
Point extracting means for extracting a plurality of n points (n is a natural number of 3 or more) from the outer side of the member, first-order approximation formula creating means for obtaining a first-order approximation equation from the n points, and the first-order approximation equation Until the number of remaining points excluding the point farthest away from is equal to or less than a predetermined value smaller than n, the process of excluding the point farthest from the primary approximate expression is repeated, and the primary approximate expression is calculated from the remaining points. An outer shape recognizing device, comprising: a first approximation formula re-creating means for re-determining, recognizing the outer shape of the member as the inclination a of the re-created first approximation formula Y = a × X + b.

Images