CN115961340A - Method for determining aperture area of crystal bar in seeding process - Google Patents
Method for determining aperture area of crystal bar in seeding process Download PDFInfo
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- CN115961340A CN115961340A CN202111174627.5A CN202111174627A CN115961340A CN 115961340 A CN115961340 A CN 115961340A CN 202111174627 A CN202111174627 A CN 202111174627A CN 115961340 A CN115961340 A CN 115961340A
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Abstract
The invention discloses a method for determining an aperture area of a crystal bar in a seeding process, which comprises the following steps: establishing a coordinate system, establishing the coordinate system by using a gray scale image of an aperture, wherein an X axis is a row number, a Y axis is a column number, and each point (X, Y) on the image corresponds to a pixel value; determining the number of lines of the interface M according to the average value of the line pixel points; the area below the line where the interface M is located is treated to be black, and the area above the line where the interface M is located is an aperture area. The method can greatly reduce the threshold value of the aperture, can not cause false detection even if the brightness of the aperture is greatly changed, greatly improves the stability of aperture detection, and can improve the anti-interference performance of a system. The method carries out the pre-treatment of removing the reflection on the image in the early stage of the calculation of the measurement of the diameter and the liquid level height, and is the stability of the measurement of the diameter and the liquid level height in the later crystal bar growing process.
Description
Technical Field
The invention relates to the technical field of image processing, in particular to a method for determining an aperture area of a crystal bar in a seeding process.
Background
A single crystal furnace: the single crystal furnace is a device for melting polycrystalline materials such as polycrystalline silicon and the like by a graphite heater in an inert gas (mainly argon and helium) environment and growing dislocation-free single crystals by a Czochralski method.
In the seeding process, the aperture forms a bright inverted image under the liquid level, as shown in fig. 1, when the camera determines the threshold value boundary of the aperture (in the shape of bright crescent in fig. 1), the problem that the threshold value is difficult to determine due to the fact that the inverted image is too bright and the actual aperture boundary is detected by mistake, namely the inverted image is detected as the actual aperture, so that the measurement error is caused.
Disclosure of Invention
In view of the above technical deficiencies, the present invention provides a method for determining an aperture area of an ingot during seeding, so as to solve the problems in the prior art.
In order to solve the technical problem, the invention adopts the following technical scheme:
the invention provides a method for determining an aperture area of a crystal bar in a seeding process, which comprises the following steps:
(1) Establishing a coordinate system
Establishing a coordinate system by using a gray scale image of the aperture, wherein an X axis is a row number, a Y axis is a column number, each point (X, Y) on the image corresponds to a pixel value, and the row number R, the column number C and the pixel value are automatically stored in the camera and are known data;
(2) Determining the number of lines of the interface M according to the average value of the line pixel points;
(3) The area below the line of the interface M is processed to be black, and the area above the line of the interface M is an aperture area.
Preferably, in the step (2), a curve AVG diagram is drawn with the row number as the abscissa and the row pixel average value as the ordinate, and the range of the row number of the interface M is determined by the row number of the trough M in the diagram.
Preferably, in step (2), the graph of the curve AVG is derived to obtain the rate of change DEV = AVG', and the derivative is plotted, where the maximum rate of change is N points, and the number of rows where the interface M is located is the closest to the N points, and the number of rows is greater than N points, and the point where the average value of the row pixel is the minimum, with reference to the row pixel average value and the derivative comparison table.
Preferably, in step (2), the specific way to take the average value of the row pixels is:
there are C total points in each line of the image, the x-th line is calculated, the average value Ax of all point pixels in each line,
Ax＝(A1+A2+A3...A c general )/C General (1) (1)。
Preferably, in step (1), the number of rows is 533 rows, the number of columns is 280 columns, the pixel value of the dot in the picture is between 0 and 255, the pixel value of black is 0, and the pixel value of white is 255.
Preferably, in the step (2),
M1＝N1+X (2)
m1 is the number of lines of the interface M; n1 is the number of rows where the maximum value N of the average rate of change of the row pixels is located, X is the offset, and X is a positive value.
Preferably, in step (3), the area below the M interface is processed to be black in a manner of changing all pixel values below the M interface to 0.
The invention has the beneficial effects that:
(1) The invention utilizes the mirror symmetry principle, calculates the average value of the row pixels, makes a curve for the average value of the row pixels, determines the range of the number of rows of the interface M through the wave trough M, and then conducts derivation on the curve to find the point N with the minimum derivative, wherein the M point is below the N point in a gray scale image, so the number of rows of M is larger than the number of rows of N, and the position of M can be definitely determined by combining the average value of the row pixels and a derivative comparison table, namely the position of the interface M of the aperture and the reflection of the aperture can be determined. And then, the area below the interface M is completely processed into black, so that the integrity of the aperture can be ensured, the threshold value of the aperture can be greatly reduced, even if the brightness of the aperture is greatly changed, false detection can not be caused, the stability of aperture detection is greatly improved, and the anti-interference performance of the system can be improved.
(2) In the method, the image is subjected to reflection removing pretreatment in the initial stage of seeding, namely the early stage of calculation of the diameter and liquid level height measurement, so that the stability of the diameter and liquid level height measurement in the later crystal bar growth process is realized.
(3) The method is simple to operate and convenient to use, and provides a basis for the controllable growth of the crystal bar.
(4) The invention can avoid the interference of the reflection in the image processing by processing the reflection into black, and the theory and the practice are verified.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a gray scale view of an ingot aperture and its reflection;
FIG. 2 is a schematic diagram of a coordinate system of the aperture and its reflection in FIG. 1;
FIG. 3 is a diagram of an AVG curve relating line pixel average to line number;
FIG. 4 is a graph of the average rate of change of row pixel values versus the number of rows after the derivation of FIG. 3;
fig. 5 is a partial enlarged view of fig. 1, in which the position 1 is a point N.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The embodiment is as follows:
the invention provides a method for determining an aperture area of a crystal bar in a seeding process, which comprises the following steps:
(1) Establishing a coordinate system
According to the mirror imaging principle, the aperture and the inverted image thereof are in mirror symmetry with respect to the liquid level, a relatively dark area necessarily exists between the aperture and the inverted image thereof, the area is the position of the interface M, a coordinate system is established by using a gray scale map of the aperture in fig. 1, as shown in fig. 2, the X axis is the number of rows, the Y axis is the number of columns, each point (X, Y) on the image corresponds to one pixel value, the number of rows, the number of columns and the pixel value are automatically stored in the camera, the known data is known, in the embodiment, the number of rows is 533, the number of columns is 280, the pixel value of a point in the picture is between 0 and 255, the pixel value of black is 0, and the pixel value of white is 255.
(2) Taking the average value of the line pixels
The image has 280 points per line, and the average value of all the point pixels in each line is calculated
The average data of the row pixels is shown in table 1, where the row number is the abscissa and the average of the row pixels is the ordinate, and the result is plotted as shown in a curve AVG in fig. 3, where the position of the trough M in fig. 3 is the position of the interface M; from the analysis of fig. 2, it can be seen that, from top to bottom, as the number of rows increases, the pixel value increases, when the pixel value reaches the aperture, the pixel value is maximum, when the pixel value reaches the area between the aperture and the reflection, the pixel value becomes dark, that is, the pixel value decreases, when the pixel value reaches the aperture, the pixel value increases, the analysis result corresponds to fig. 3, and the position of the trough M in fig. 3 is the position of the boundary mirror M in fig. 2.
(3) Determining M point locations
Since there may be a plurality of points in fig. 3 that are the same as the M-point value, for example, the positions of valleys may also occur in the reflection portion, the curve AVG in fig. 3 is differentiated to obtain the change rate DEV = AVG', the specific values of the derivatives are shown in table 1, and the derivatives are plotted at the same time, as shown in fig. 4, the result is that the point in the graph with the maximum change rate is N points, i.e., the point with the highest brightness decreasing from light to dark is the fastest;
in this embodiment, referring to fig. 3, the trough M is near 240 rows, referring to fig. 4, the point N with the largest change rate is near 235 rows, and then, with reference to table 1, the row where the derivative from near 235 rows to the minimum point is located is found out, N1=236 is obtained quickly, then, the row where the point with the smallest row pixel average value is located is found out to be closest to the point N and is greater than N points, and M1=242 is obtained quickly, it can be seen that the row where the point with the smallest row pixel average value is located is not the same as the row where the point with the largest row pixel average value change rate, and the difference between the two rows is 6 rows.
With reference to table 1 and fig. 5, the line where the interface M is located is the line where the average value of the line pixels is the minimum, the point where the average value change rate of the line pixels is the maximum is position No. 1, the position at the bottom of the aperture, i.e., the position from the presence to the absence of the pixels, and there is a certain distance, i.e., the offset, between the position No. 1 and the interface M. The following equation is derived:
M1＝N1+X (2)
m1 is the number of lines where the interface M is located; n1 is the row number where the maximum value N of the average value change rate of the row pixels is located, X is the offset, and X can be adjusted according to actual conditions.
In this embodiment, X =6.
(4) Removing inverted image
All pixel values below the M interface are changed to 0 in the camera setting, i.e., the area below the M interface is all treated as black.
In this embodiment, the pixel values below 242 rows are all changed to 0, that is, the area below the M interface is all processed to be black, so that the interference of reflection can be eliminated in the seeding process.
TABLE 1 row Pixel mean and derivative LUT
In the seeding process, the camera takes pictures every hundreds of milliseconds, and the reflection processing of the method is carried out every time the pictures are taken, so the reflection processing is a continuous process.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (7)
1. A method for determining an aperture area of a crystal bar in a seeding process is characterized by comprising the following steps:
(1) Establishing a coordinate system
Establishing a coordinate system by using a gray scale image of the aperture, wherein an X axis is a row number, a Y axis is a column number, each point (X, Y) on the image corresponds to a pixel value, and the row number R, the column number C and the pixel value are automatically stored in the camera and are known data;
(2) Determining the number of lines of the interface M according to the average value of the line pixel points;
(3) The area below the line where the interface M is located is treated to be black, and the area above the line where the interface M is located is an aperture area.
2. The method of claim 1, wherein in step (2), the range of M number of lines of the boundary surface is determined by a valley M by plotting AVG with the number of lines as abscissa and the mean value of the pixels of the lines as ordinate.
3. The method as claimed in claim 2, wherein in the step (2), the derivative of the curve AVG is derived to obtain the change rate DEV = AVG', and the derivative is plotted, wherein the maximum change rate is N points, the row pixel average value and the derivative comparison table are referred, the number of rows where the interface M is located is the closest to the N points, the number of rows is greater than the N points, and the row pixel average value is the smallest.
4. The method of claim 2, wherein in step (2), the averaging of the rows of pixels in step (2) is performed by:
each line in the image has C General (1) Calculating the x-th row, the average value of all the point pixels in each row
5. The method of claim 4, wherein in step (1), the number of rows is 533, the number of columns is 280, the pixel value of the point in the picture is between 0 and 255, the pixel value of black is 0, and the pixel value of white is 255.
6. A method for determining the aperture area of a crystal bar during seeding as claimed in claim 3, wherein in step (2),
M1＝N1+X (2)
m1 is the number of lines where the interface M is located; n1 is the row number where the maximum value N of the average value change rate of the row pixels is located, X is the offset, and X is a positive value.
7. The method according to claim 1, wherein in the step (3), the area below the M interface is processed to be black in a manner that all pixel values below the M interface are changed to 0.
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| CN202111174627.5A CN115961340A (en) | 2021-10-09 | 2021-10-09 | Method for determining aperture area of crystal bar in seeding process |
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| CN202111174627.5A CN115961340A (en) | 2021-10-09 | 2021-10-09 | Method for determining aperture area of crystal bar in seeding process |
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