WO2018010386A1

WO2018010386A1 - Method and system for component inversion testing

Info

Publication number: WO2018010386A1
Application number: PCT/CN2016/113129
Authority: WO
Inventors: 李红匣
Original assignee: 广州视源电子科技股份有限公司
Priority date: 2016-07-13
Filing date: 2016-12-29
Publication date: 2018-01-18
Also published as: CN106204602A; CN106204602B

Abstract

A method and system for component inversion testing. The method comprises the following steps: acquiring a polarity area image and a symmetric polarity area image of a component to be tested on a circuit board (S1), where a polarity area is an area in which an electrode of the component to be tested is located on the circuit board when mounted correctly, and a symmetric polarity area is an area in which the electrode is located on the circuit board when the component is inverted; respectively calculating a first color similarity between the polarity area image and a prestored polarity area reference image and a second color similarity between the symmetric polarity area image and the polarity area reference image (S2); and if the first color similarity is less than the second color similarity, determining that the component to be tested is inverted (S3). The method and system for component inversion testing obviate the need for a large amount of training samples, require simply the acquisition of the polarity area and the symmetric polarity area of the component, is simple to operate, provides high recognition rate, and has improved testing effects.

Description

Component reverse component detecting method and system

Technical field

The present invention relates to the field of automatic optical detection technology, and in particular to a method and system for detecting component reverse parts.

Background technique

AOI (Automatic Optic Inspection) is a device that uses optical principles to detect common defects in board soldering production. For the board of the plug-in, common defect detection includes missing parts detection, wrong part detection, reverse part detection, multi-piece detection, and the like. Among them, the reverse component detection refers to the detection of polar components such as diodes, capacitors, and sockets, and judges whether there is a reverse phenomenon in the circuit board.

At present, the component detection of the component is mainly based on the intelligent method, that is, the deep learning method is used to train a large number of samples to obtain a classification model. Deep learning is a new field of machine learning research. Its purpose is to simulate the mechanism of the human brain to interpret data and discover distributed feature representations of data. The learning models established under different learning frameworks are also different. For example, Convolutional Neural Networks (CNNs) is a deep machine learning model.

The component polarity detection classifier trained by the convolutional neural network, although achieving a desirable effect in the polarity detection of the component, has its own drawbacks that cannot be solved by itself. First, when using the convolutional neural network to train the model, in order to improve the accuracy of the model and enhance the robustness of the model, a large number of training samples are needed. However, in the actual process, it takes a lot of manpower and time to collect samples; when collecting more training samples, it also requires a lot of manpower and time for data labeling. Even so, it is difficult to collect enough negative samples. In addition, the component polarity detection model trained by the convolutional neural network has a high recognition rate for known components and can achieve a good detection effect. However, for unknown components, that is, components that do not exist in the training sample, the recognition rate of the component polarity detection model decreases, and false positives and false negatives often occur.

In summary, the existing component polarity detection method has a poor detection effect.

Summary of the invention

Based on this, it is necessary to provide a method and system for detecting component reverse parts in view of the problem that the existing component polarity detection method has poor detection effect.

A method for detecting a component reverse component includes the following steps:

Obtaining a polar area image and a polar symmetric area image of the device to be tested on the circuit board; wherein the polarity area is an area where the electrode of the device to be tested is mounted on the circuit board, and the polarity symmetry area is reversed The area of the electrode on the circuit board;

Calculating, respectively, a first color similarity of the polar region image and the pre-stored polar region reference image, and a second color similarity of the polar symmetric region image and the polar region reference image;

If the first color similarity is less than the second color similarity, determining the component to be tested is reversed.

A component reverse component detecting system includes:

Obtaining a module, configured to obtain an image of a polar region and a region of a polar symmetric region of the device to be tested on the circuit board; wherein the polarity region is an area of the electrode of the device to be tested on the circuit board when the polarity is correctly installed, The region of the electrode on the circuit board when the symmetrical region is the reverse member;

a calculating module, configured to separately calculate a first color similarity of the polar area image and the pre-stored polar area reference image, and a second color similarity of the polar symmetric area image and the polar area reference image ;

a determining module, configured to determine, when the first color similarity is less than the second color similarity, the component to be tested.

The component reverse component detecting method and system calculate a polar symmetric region image of the device to be tested and the polar region reference image by calculating a first color similarity between the polarity region image of the device to be tested and the polar region reference image a second color similarity, when the first color similarity is smaller than the second color similarity, indicating that a difference between the polar symmetric region image of the device to be tested and the polar region reference image is small, and the The difference between the polar region image of the measuring element and the polar region reference image is large, thereby determining the component counter. The above component reverse component detecting method and system do not require a large number of training samples, and only need to acquire the polar region and the polar symmetric region of the component, and the operation is simple, the recognition rate is high, and the detection effect is good.

DRAWINGS

1 is a flow chart of a method for detecting a component reverse member of an embodiment;

2 is a schematic view of a polar region and a polar symmetric region;

3 is a schematic diagram of a template matching method;

Figure 4 is a schematic diagram of the HSV color space;

Fig. 5 is a schematic structural view of an element reverse detecting system of an embodiment.

detailed description

Embodiments of the component reverse member detecting method and system of the present invention will be described below with reference to the accompanying drawings.

1 is a flow chart of a method for detecting a component reverse member of an embodiment. As shown in FIG. 1, the component reverse component detecting method may include the following steps:

S1, acquiring a polar region image and a polar symmetric region image of the device to be tested on the circuit board; wherein, the polar region is a region on the circuit board where the electrode of the device to be tested is correctly mounted, and the polar symmetric region The area of the electrode on the circuit board when the component is reversed;

A schematic diagram of the polar region and the polar symmetric region of the present invention is shown in FIG.

The image of the circuit board may be acquired first, and then the polar region and the polar symmetric region are located from the image of the circuit board, and the polar region and the polar symmetric region are respectively intercepted from the image of the circuit board. The corresponding image is set as the polar area image and the polar symmetrical area image.

In one embodiment, the polar region image may be acquired by a template matching method. The template matching method is shown in Figure 3. Specifically, a first image region matching the polar region reference image may be selected from the image of the circuit board; and pixels of each pixel in the reference image according to the first image region and the polar region may be selected a value, a first pixel similarity of the image region to the polar region reference image is calculated; and a first image region having a first pixel similarity greater than or equal to a preset first pixel similarity threshold is set as Polar area image. The polar area reference image may be pre-stored in a storage area of the system and called from the storage area when the polar area image is acquired.

If the first pixel similarity is less than a preset first pixel similarity threshold, an area of the image of the circuit board adjacent to the first image area may be set as the first image area, and repeated A step of calculating a first pixel similarity of the first image region and the polar region reference image. The area adjacent to the first image area is an area obtained by moving the first image area to the x-axis and the y-axis by a plurality of pixel points in an image of the circuit board. In the above steps, each moving pixel point may be one pixel point or multiple pixel points, and the moving distance may be set according to actual needs.

Similarly, the polar symmetric region image can also be acquired by a template matching method. Specifically, a second image region matching the polar symmetric region reference image may be selected from the image of the circuit board; Calculating a second pixel similarity of the image region and the polar symmetric region reference image by using a pixel value of each pixel point in the second image region and the polar symmetric region reference image; and comparing the second pixel similarity to or A second image region equal to a preset second pixel similarity threshold is set as the polar symmetric region image. The polar symmetric region reference image may be pre-stored in a storage area of the system and called from the storage region when the polar region image is acquired.

If the second pixel similarity is less than a preset second pixel similarity threshold, an area adjacent to the second image area in the image of the circuit board may be set as the second image area, and repeated And calculating a second pixel similarity of the second image region and the polar region reference image. The area adjacent to the second image area is an area obtained by moving the second image area to the x-axis and the y-axis by a plurality of pixel points in an image of the circuit board. In the above steps, each moving pixel point may be one pixel point or multiple pixel points, and the moving distance may be set according to actual needs.

The polar area image and the polar symmetric area image may also be acquired according to other methods.

In the above embodiment for acquiring the polar region image and the polar symmetric region image, the first pixel similarity and the second pixel similarity may be calculated according to the following formula:

Where R(x, y) is the pixel similarity of the pixel of the image region and the coordinate region (x, y) in the polar region reference image, and T(x, y) is the polar region The pixel value of the pixel at coordinates (x, y) in the reference image, I(x, y) is the pixel value of the pixel at coordinates (x, y) in the image region.

The first pixel similarity threshold may be set according to actual needs. For example, it can be set to 0.8, or set to 0.9, or set to other values. The larger the first pixel similarity threshold, the higher the accuracy of image acquisition.

S2, respectively calculating a first color similarity of the polar area image and the pre-stored polar area reference image, and a second color similarity of the polar symmetric area image and the polar area reference image;

When the polar region and the polar symmetric region of the element to be tested have sharp color differences, it is possible to detect whether the component is reversed according to the color similarity. In order to more intuitively compare the image of the component to be tested with the reference image, the color histogram of the image of the component and the reference image can be compared.

Before the comparison, the image of the component to be tested can also be converted to the HSV color space. HSV color space indication The figure is shown in Figure 4. In image processing, the most commonly used color space is the RGB model, which is often used for color display and image processing. The HSV model is a color model for the user's perception, focusing on the representation of color. Among them, R, G, B refer to red, green, and blue colors respectively; H refers to hue, which ranges from 0 to 360 degrees, and is used to indicate the color category, such as red is 0 degrees green is 120 degrees, blue It is 240 degrees; S refers to saturation, the value range is 0% to 100%, used to indicate the vividness of the color, such as the saturation of gray is 0%, the saturation of red (255,0,0) is 100% V refers to the brightness, the value range is 0% to 100%, used to indicate the degree of light and darkness of the color, such as black brightness is 0%, white brightness is 100%. Compared to RGB space, HSV space can express the brightness, color and vividness of colors very intuitively.

The pixel values of the polar region image can be converted to the HSV color space according to the following formula:

Where max = max(R, G, B);

Min=min(R, G, B);

V=max;

S=(max-min)/max;

H=H+360, ifH<0

0 ≤ V ≤ 1, 0 ≤ S ≤ 1, 0 ≤ H ≤ 360;

R, G, and B are the color components of the RGB space.

For example, when calculating a first color similarity of the polar area image and the pre-stored polar area reference image, a first color histogram of the polar area image may be acquired, according to the first color histogram The first color similarity is calculated by the number of pixel points of each component amount and the number of pixel points of the corresponding component in the second color histogram of the polar region reference image.

Similarly, when calculating a second color similarity of the polar symmetric region image and the polar region reference image, a third color histogram of the polar symmetric region image may be acquired, according to the third color The second color similarity is calculated by the number of pixel points of each component amount in the histogram and the number of pixel points of the corresponding component in the second color histogram.

Wherein, the color histogram may be a color histogram of the H-S channel.

In one embodiment, the first color similarity can be calculated according to the following formula:

Where d ₁ is the first color similarity, and H ₁ (I) is the number of pixel points of the first component amount in the first color histogram,

The average number of pixels of each component amount in the first color histogram, H _{1 '} (I) is the number of pixel points of the first component amount in the second color histogram,

The average number of pixels of each component amount in the second color histogram;

Similarly, the second color similarity can be calculated according to the following formula:

Where d ₂ is the second color similarity, and H ₂ (I) is the number of pixel points of the first component amount in the third color histogram,

The average number of pixels of each component amount in the third color histogram.

In other embodiments, color similarity may also be calculated in other ways. For example, Chi-Square can be used. Taking the first color similarity as an example, the first color similarity can be calculated according to the following formula:

Color similarity can also be calculated according to the Intersection algorithm. Specifically, the first color similarity can be calculated according to the following formula:

Color similarity can also be calculated from Bhattacharyya. Specifically, the first color similarity can be calculated according to the following formula:

Where N is the number of histogram bins.

The way to calculate the similarity of the second color is similar, and will not be described here.

S3. If the first color similarity is less than the second color similarity, determine the component to be tested.

In one embodiment, the component may be dirty for some reason, ie a non-polar region of the component may appear The color of the polar region is similar, and in order to ensure the correct rate, the third color similarity between the polar region image and the pre-stored polar symmetric region reference image, and the polar symmetric region image and the pre-stored pole may be separately calculated. a fourth color similarity of the symmetrical region reference image; if the first color similarity is less than the second color similarity, and the third color similarity is greater than the fourth color similarity, determining the waiting Test component reverse.

The manner of calculating the third color similarity and the fourth color similarity may be similar to the manner of calculating the first color similarity and the second color similarity, and details are not described herein again.

The component reverse member detecting method of the present invention has the following advantages:

(1) It does not need a large number of training samples, and does not require a lot of manpower and time for data labeling. It only needs to obtain the polar region and the polar symmetric region of the component, which is simple and effective, reduces the labor cost, and has high detection efficiency;

(2) Using the color histogram, it is possible to visually detect whether the component is reversed, the recognition rate is high, and the detection effect is good.

(3) The automatic detection of component polarity can be realized, which further reduces the labor cost and improves the detection efficiency.

(4) By comparing the polar region image and the polar symmetry region of the device to be tested with the reference image of the polar region, and simultaneously referring to the polar region image and the polar symmetry region of the device to be tested and the polar symmetry region The images are compared to further improve the recognition rate and reduce the probability of false positives and false negatives.

Corresponding to the component reverse component detecting method, the present invention further provides a component reverse component detecting system. As shown in FIG. 2, the component reverse component detecting system may include:

The obtaining module 10 is configured to obtain an image of a polar region and a region of a polar symmetry region of the device to be tested on the circuit board; wherein, the polar region is an area of the electrode of the device to be tested on the circuit board when the device is correctly installed. The region of the electrode on the circuit board when the polar symmetric region is the reverse member;

In one embodiment, the polar region image may be acquired by a template matching method. The template matching method is shown in Figure 3. Specifically, a first image region matching the polar region reference image may be selected from the image of the circuit board; and pixels of each pixel in the reference image according to the first image region and the polar region may be selected a value, a first pixel similarity of the image region to the polar region reference image is calculated; and a first image region having a first pixel similarity greater than or equal to a preset first pixel similarity threshold is set as Polar area image. The polar region The test image may be pre-stored in a storage area of the system and called from the storage area when the polar area image is acquired.

If the first pixel similarity is less than a preset first pixel similarity threshold, an area of the image of the circuit board adjacent to the first image area may be set as the first image area, and repeated A step of calculating a first pixel similarity of the first image region and the polar region reference image. The area adjacent to the first image area is an area obtained by moving the first image area to the x-axis and the y-axis by a plurality of pixel points in an image of the circuit board. The pixel point of each movement may be one pixel point or multiple pixel points, and the moving distance may be set according to actual needs.

Similarly, the polar symmetric region image can also be acquired by a template matching method. Specifically, a second image region matching the polar symmetric region reference image may be selected from the image of the circuit board; and each pixel in the reference image is referenced according to the second image region and the polar symmetric region a pixel value, calculating a second pixel similarity of the image region and the polar symmetric region reference image; and setting a second image region having a second pixel similarity greater than or equal to a preset second pixel similarity threshold Is the image of the polar symmetric region. The polar symmetric region reference image may be pre-stored in a storage area of the system and called from the storage region when the polar region image is acquired.

If the second pixel similarity is less than a preset second pixel similarity threshold, an area adjacent to the second image area in the image of the circuit board may be set as the second image area, and repeated And calculating a second pixel similarity of the second image region and the polar region reference image. The area adjacent to the second image area is an area obtained by moving the second image area to the x-axis and the y-axis by a plurality of pixel points in an image of the circuit board. The pixel point of each movement may be one pixel point or multiple pixel points, and the moving distance may be set according to actual needs.

Where R(x, y) is the pixel of the image region and the polar region reference image with coordinates (x, y) Pixel similarity, T(x, y) is a pixel value of a pixel having a coordinate of (x, y) in the reference image of the polar region, and I(x, y) is a coordinate of the image region (x, y) The pixel value of the pixel.

a calculating module 20, configured to separately calculate a first color similarity of the polar area image and the pre-stored polar area reference image, and the polar symmetric area image is similar to the second color of the polar area reference image degree;

Before the comparison, the image of the component to be tested can also be converted to the HSV color space. A schematic diagram of the HSV color space is shown in Figure 4. In image processing, the most commonly used color space is the RGB model, which is often used for color display and image processing. The HSV model is a color model for the user's perception, focusing on the representation of color. Among them, R, G, B refer to red, green, and blue colors respectively; H refers to hue, which ranges from 0 to 360 degrees, and is used to indicate the color category, such as red is 0 degrees green is 120 degrees, blue It is 240 degrees; S refers to saturation, the value range is 0% to 100%, used to indicate the vividness of the color, such as the saturation of gray is 0%, the saturation of red (255,0,0) is 100% V refers to the brightness, the value range is 0% to 100%, used to indicate the degree of light and darkness of the color, such as black brightness is 0%, white brightness is 100%. Compared to RGB space, HSV space can express the brightness, color and vividness of colors very intuitively.

Where max = max(R, G, B);

Min=min(R, G, B);

V=max;

S=(max-min)/max;

H=H+360, ifH<0

0 ≤ V ≤ 1, 0 ≤ S ≤ 1, 0 ≤ H ≤ 360;

R, G, and B are the color components of the RGB space.

Wherein, the color histogram may be a color histogram of the H-S channel.

Where N is the number of histogram bins.

The determining module 30 is configured to determine the component to be tested as the first color similarity is less than the second color similarity.

In one embodiment, the component may be dirty for some reason, that is, a non-polar region of the component may have a color similar to that of the polar region. To ensure the correct rate, the image of the polar region may be separately calculated. a third color similarity of the pre-stored polar symmetric region reference image, and a fourth color similarity of the polar symmetric region image and the pre-stored polar symmetric region reference image; if the first color similarity is less than the a second color similarity, and the third color similarity is greater than the fourth color similarity, and determining the component to be tested.

The component counter detection system of the present invention has the following advantages:

The component reverse component detecting system of the present invention has a one-to-one correspondence with the component reverse component detecting method of the present invention, and the technical features and the beneficial effects thereof described in the embodiment of the component reverse component detecting method are applicable to the embodiment of the component reverse component detecting system. In this regard, hereby declare.

The technical features of the above-described embodiments may be arbitrarily combined. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as the combination of these technical features does not exist, the spear is not present. Shield should be considered as the scope of this manual.

The above-described embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims

A component reverse component detecting method, comprising the steps of:

Obtaining a polar area image and a polar symmetric area image of the device to be tested on the circuit board; wherein the polarity area is an area where the electrode of the device to be tested is mounted on the circuit board, and the polarity symmetry area is reversed The area of the electrode on the circuit board;

Calculating, respectively, a first color similarity of the polar region image and the pre-stored polar region reference image, and a second color similarity of the polar symmetric region image and the polar region reference image;

If the first color similarity is less than the second color similarity, determining the component to be tested is reversed.
The method of detecting a component reverse component according to claim 1, wherein the step of acquiring an image of a polar region of the component comprises:

Selecting an image region matching the polar region reference image from the image of the circuit board;

Calculating a pixel similarity of the image region and the polar region reference image according to pixel values of the image regions and the pixel values in the polar region reference image;

An image area having a pixel similarity greater than or equal to a preset pixel similarity threshold is set as the polarity area image.
The component reverse component detecting method according to claim 2, further comprising the following steps after calculating the pixel similarity of the image region and the polar region reference image:

If the pixel similarity is less than a preset pixel similarity threshold, an area of the image of the circuit board adjacent to the image area is set as the image area;

Repetitively calculating a pixel similarity of the image region and the polar region reference image;

The area adjacent to the image area is an area obtained by moving the image area to the x-axis and the y-axis by a plurality of pixel points in an image of the board.
The component reverse component detecting method according to claim 2, wherein the calculating the pixel similarity of the image region and the polar region reference image comprises:

The pixel similarity is calculated according to the following formula:

Where R(x, y) is the pixel of the image region and the polar region reference image with coordinates (x, y) Pixel similarity, T(x, y) is a pixel value of a pixel having a coordinate of (x, y) in the reference image of the polar region, and I(x, y) is a coordinate of the image region (x, y) The pixel value of the pixel.
The component reverse component detecting method according to claim 1, wherein the calculating the first color similarity of the polar region image and the pre-stored polar region reference image comprises:

Obtaining a first color histogram of the image of the polar region;

Calculating the first color similarity according to the number of pixel points of each component amount in the first color histogram and the number of pixel points of corresponding components in the second color histogram of the polar region reference image;

The step of calculating the second color similarity of the polar symmetric region image and the polar region reference image comprises:

Obtaining a third color histogram of the polar symmetric region image;

The second color similarity is calculated according to the number of pixel points of each component amount in the third color histogram and the number of pixel points of the corresponding component in the second color histogram.
The component reverse component detecting method according to claim 5, wherein the step of calculating the first color similarity according to the first color parameter and the second color parameter comprises:

The first color similarity is calculated according to the following formula:

Where d 1 is the first color similarity, and H 1 (I) is the number of pixel points of the first component amount in the first color histogram,
The average number of pixels of each component amount in the first color histogram, H 1 ' (I) is the number of pixel points of the first component amount in the second color histogram,
The average number of pixels of each component amount in the second color histogram;

The step of calculating the second color similarity according to the third color parameter and the second color parameter comprises:

The second color similarity is calculated according to the following formula:

Where d 2 is the second color similarity, and H 2 (I) is the number of pixel points of the first component amount in the third color histogram,
The average number of pixels of each component amount in the third color histogram.
The component reverse member detecting method according to claim 1, wherein said polar region map is calculated Before the first color similarity with the polar region reference image, the following steps are also included:

Converting the pixel values of the polar region image to the HSV color space.
The component reverse component detecting method according to claim 7, wherein the converting the pixel value of the polar region image to the HSV color space comprises:

The pixel values of the polar region image are converted to the HSV color space according to the following formula:

Where max = max(R, G, B);

Min=min(R, G, B);

V=max;

S=(max-min)/max;

H=H+360, ifH<0

0 ≤ V ≤ 1, 0 ≤ S ≤ 1, 0 ≤ H ≤ 360;

R, G, and B are the color components of the RGB space.
The component reverse component detecting method according to claim 1, wherein before the determining the component to be tested, the method further comprises the following steps:

Calculating, respectively, a third color similarity of the polar region image and the pre-stored polar symmetric region reference image, and a fourth color similarity of the polar symmetric region image and the pre-stored polar symmetric region reference image;

And if the first color similarity is less than the second color similarity, and the third color similarity is greater than the fourth color similarity, determining the component to be tested.
A component reverse component detecting system, comprising:

Obtaining a module, configured to obtain an image of a polar region and a region of a polar symmetric region of the device to be tested on the circuit board; wherein the polarity region is an area of the electrode of the device to be tested on the circuit board when the polarity is correctly installed, The region of the electrode on the circuit board when the symmetrical region is the reverse member;

a calculating module, configured to separately calculate a first color similarity of the polar area image and the pre-stored polar area reference image, and a second color similarity of the polar symmetric area image and the polar area reference image ;

a determining module, configured to determine the component to be tested if the first color similarity is less than the second color similarity Reverse pieces.