A PCB board defect image acquisition device based on dual-band polarization imaging

Abstract

The present invention discloses a PCB board defect image acquisition device based on dual-band polarization imaging, including a light-shielding shell, an image acquisition module and an adjustment frame located therein. The image acquisition module includes: an adapter, including a horizontal top surface and a 45° inclined side surface, and a through hole is provided on the horizontal top surface; a spectroscope, installed on the inclined side surface of the adapter; a visible light polarization camera, located above the horizontal top surface, with its lens facing downward, and its optical center is coaxial with the through hole; an infrared polarization camera, horizontally arranged on the side of the adapter, with its lens facing the spectroscope, and its optical center is coaxial with the spectroscope; a bottom plate is located below the adapter; and the adjustment frame includes: three adjustment devices, which are respectively connected to the adapter, the visible light polarization camera and the infrared polarization camera. The problem that the existing visible light-based acquisition device has low detection accuracy due to a single information source and the image quality is easily affected by ambient light is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of image acquisition, and in particular relates to a PCB board defect image acquisition device based on dual-band polarization imaging. Background Art

[0002] Printed PCB (PCB) is the basic structural unit of various contemporary electronic products. It can greatly reduce the probability of errors in the wiring and assembly process, save space and improve the efficiency of automated production. In recent years, with the improvement of production processes and the emergence of new technologies, printed PCBs are developing in the direction of high density and light weight. Existing detection methods, such as manual visual detection, rely on the experience of workers, are highly subjective and inefficient, and it is difficult to meet the high-speed and high-accuracy detection requirements of modern industry. As the volume of PCBs becomes smaller and smaller, the spatial resolution of the human eye is limited, and the detection results are uncertain and ambiguous. Electronic detection belongs to contact detection, and the detection sensor is in direct contact with the object to be detected. There is a risk of failure due to physical contact, and the detection efficiency and accuracy of increasingly dense PCB boards are low. Optical detection technology uses optical lighting and image sensing technology to obtain information about the printed PCB to be detected, and detects it through the back-end digital image processing technology. As a non-destructive, fast and accurate detection method, optical-based detection technology has become the main development direction of current printed PCB defect detection.

[0003] However, optical detection has the following problems:

[0004] 1) Existing image acquisition equipment mainly uses industrial cameras to capture visible light intensity images of PCB boards, which cannot identify some defects. When the proportion of pixels occupied by the defective part in the overall image is too small, such as tiny burrs on the edge, or the grayscale difference between the defective part and the overall image is too small, such as tiny circuit breaks and cold solder joints in through holes, the existing intensity map cannot provide effective difference information for subsequent detection algorithms to process, resulting in missed detection.

[0005] 2) At the same time, the visible light intensity map is easily affected by ambient light, and inconsistent lighting conditions can lead to imaging deviations, which can cause false detections.

[0006] 3) In addition, optical detection technology is relatively mature abroad, and there are already devices with relatively good detection effects, but they are large in size and expensive. Summary of the invention

[0007] The purpose of the present invention is to provide a PCB board defect image acquisition device based on dual-band polarization imaging to solve the problems of low detection accuracy and image quality being easily affected by ambient light in existing acquisition devices based on visible light due to a single information source.

[0008] The present invention adopts the following technical scheme: a PCB board defect image acquisition device based on dual-band polarization imaging, comprising a light-shielding shell, and an image acquisition module and an adjustment rack located therein;

[0009] The image acquisition module specifically includes:

[0010] An adapter, comprising a horizontal top surface and a 45° inclined side surface, wherein the horizontal top surface is provided with a through hole;

[0011] a beam splitter mounted on the inclined side surface of the adapter;

[0012] a visible light polarization camera, located above the horizontal top surface, with its lens facing downward and its optical center coaxial with the through hole;

[0013] an infrared polarization camera, horizontally disposed on the side of the adapter, with its lens facing the beam splitter and its optical center coaxial with the beam splitter;

[0014] A bottom plate, located below the adapter, for placing the printed PCB to be tested;

[0015] The adjusting frame specifically comprises:

[0016] Three adjustment devices, respectively connected to the adapter, the visible light polarization camera and the infrared polarization camera, and used to adjust the heights of the adapter, the visible light polarization camera and the infrared polarization camera, and the angles between them;

[0017] The spectroscope is used to enable the visible light polarization camera and the infrared polarization camera to simultaneously collect the intensity image and polarization image of the printed PCB board to be inspected in the visible light and infrared bands.

[0018] Furthermore, the regulating device specifically includes:

[0019] Two support rods are vertically arranged on the bottom plate, the visible light polarization camera and the adapter are respectively installed on the same support rod through a detachable connecting device, and the infrared polarization camera is installed on the other support rod through a detachable connecting device.

[0020] Furthermore, the three connecting devices each include a camera clamp and a converter, one end of each camera clamp is respectively fixedly connected to one side of the visible light polarization camera, the infrared polarization camera and the adapter, and the other end of each camera clamp is installed on the support rod through the converter.

[0021] Furthermore, it also includes an illumination device, which includes two light sources arranged in parallel and opposite to each other, the two light sources are located between the adapter and the base plate, and are equidistantly distributed on both sides of the visible light polarization camera and the infrared polarization camera, which can be used to provide sufficient brightness for the printed PCB board to be inspected.

[0022] Furthermore, the lighting device is installed on any one of the support rods through a converter.

[0023] Furthermore, the lighting device is connected to a light source controller.

[0024] The second technical solution adopted by the present invention is a collection method of a PCB board defect image collection device based on dual-band polarization imaging, comprising the following contents:

[0025] S1. Adjust the vertical and horizontal positions of the light source, the visible light polarization camera, the infrared polarization camera, and the beam splitter through the converter 8. The camera fixture fine-tunes the horizontal positions of the visible light polarization camera and the infrared polarization camera so that the centers of the visible light polarization camera and the beam splitter are on the same vertical line, the centers of the infrared polarization camera and the beam splitter are on the same horizontal line, and the light sources are equidistantly distributed on both sides of the camera.

[0026] S2. Adjust the illumination angle of the light source, adjust the brightness of the light source through the light source controller, and configure a low-angle lighting environment; adjust the focal length and aperture size of the two cameras;

[0027] S3. Place the printed PCB to be inspected at the center of the bottom plate, and fine-tune the positions of the light source and the two cameras according to the preview image so that the printed PCB to be inspected is imaged at the center of the camera. The two cameras are used to collect visible light intensity images, visible light polarization images, infrared intensity images, and infrared polarization images of the printed PCB to be inspected.

[0028] The beneficial effects of the present invention are:

[0029] 1) The use of split light path and visible light polarization camera and infrared polarization camera can simultaneously collect the visible light intensity image, visible light polarization image, infrared intensity image, and infrared polarization image of the printed PCB board at the same time, providing comprehensive and complementary image information for subsequent detection;

[0030] 2) The adjustable mechanical structure can adjust the camera field of view according to the different sizes of printed PCB boards, and adjust the height, angle, and brightness of the light source, so as to construct a low-angle lighting environment and avoid high reflection of the printed PCB board; at the same time, the external light-shielding shell can avoid interference from ambient light. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1It is a structural schematic diagram of a PCB board defect image acquisition device based on dual-band polarization imaging of the present invention;

[0032] Figure 2 This is a schematic structural diagram of a PCB board defect image acquisition device based on dual-band polarization imaging without a light-shielding housing;

[0033] Figure 3 It is an enlarged schematic diagram of the image acquisition module part of the PCB board defect image acquisition device based on dual-band polarization imaging of the present invention.

[0034] Among them, 1. visible light polarization camera, 2. infrared polarization camera, 3. spectrometer, 4. light source, 5. base plate, 6. support rod, 7. fixing bolt, 8. converter, 9. camera clamp, 10. adapter, 11. light source clamp, 12. light source controller, 13. light shielding shell. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] The present invention provides a PCB board defect image acquisition device based on dual-band polarization imaging, such as Figure 1-3 As shown, it includes a light-shielding housing 13, and an image acquisition module and an adjustment rack located therein.

[0037] The image acquisition module specifically includes: an adapter 10, a beam splitter 3, a visible light polarization camera 1, an infrared polarization camera 2 and a bottom plate 5. The adapter 10 includes a horizontal top surface and a 45° inclined side surface, and a through hole is provided on the horizontal top surface; the beam splitter 3 is installed on the inclined side surface of the adapter 10; the visible light polarization camera 1 is located above the horizontal top surface, its lens is set downward, and its optical center is coaxial with the through hole; the infrared polarization camera 2 is horizontally set to the side of the adapter 10, its lens faces the beam splitter 3, and its optical center is coaxial with the beam splitter 3; the bottom plate 5 is located below the adapter 10, and is used to place the printed PCB board to be detected.

[0038] Among them, the spectroscope can transmit visible light and reflect infrared, and can simultaneously collect visible light intensity image and visible light polarization image through the visible light polarization camera, and collect infrared intensity image and infrared polarization image through the infrared polarization camera. The spectroscope is used to enable the visible light polarization camera 1 and the infrared polarization camera 2 to simultaneously collect the intensity image and polarization image of the printed PCB board to be inspected in the visible light and infrared bands. The use of the spectroscopic optical path and the visible light polarization camera and the infrared polarization camera can simultaneously collect the visible light intensity image, visible light polarization image, infrared intensity image, and infrared polarization image of the printed PCB board at the same time, providing comprehensive and complementary image information for subsequent inspections.

[0039] The adjustment frame specifically includes three adjustment devices. The three adjustment devices are respectively connected to the adapter 10, the visible light polarization camera 1 and the infrared polarization camera 2, and are respectively used to adjust the height of the adapter 10, the visible light polarization camera 1 and the infrared polarization camera 2, and the angle between them. The camera field of view can be adjusted according to the printed PCB boards of different sizes, and the height, angle and brightness of the light source can be adjusted to construct a low-angle lighting environment to avoid high reflection of the printed PCB board; at the same time, the external light-shielding shell can avoid interference from ambient light.

[0040] The adjustment device specifically includes: two support rods 6 vertically arranged on the bottom plate 5, the visible light polarization camera 1 and the adapter 10 are respectively installed on the same support rod 6 through a detachable connection device, and the infrared polarization camera 2 is installed on the other support rod 6 through a connection device. The three connection devices each include a camera fixture 9 and a converter 8, one end of each camera fixture 9 is respectively fixed to one side of the visible light polarization camera 1, the infrared polarization camera 2 and the adapter 10, and the other end of each camera fixture 9 is installed on the support rod 6 through the converter 8.

[0041] A PCB board defect image acquisition device based on dual-band polarization imaging of the present invention also includes an illumination device, which includes two light sources 4 arranged in parallel and opposite to each other, the two light sources 4 are located between the adapter 10 and the bottom plate 5, and are equidistantly distributed on both sides of the visible light polarization camera 1 and the infrared polarization camera 2, and are used to provide sufficient brightness for the printed PCB board to be inspected. The illumination device is installed on any one of the support rods 6 through a converter 8. The illumination device is connected to a light source controller 12, and the light source controller 12 is arranged outside the light shielding housing 13. The light source 4 is fixed to the support rod 6 through a light source clamp and a converter, and the distance and illumination angle between the light source and the printed PCB board can be adjusted through the light source clamp and the converter, and the brightness of the light source is adjusted through the light source controller.

[0042] The visible light polarization camera and the infrared polarization camera are fixed on the support rod through the camera clamp 9 and the converter, the spectrometer is fixed on the support rod through the adapter and the converter, the light source is fixed on the support rod through the light source clamp and the converter, the light source controller is connected to the light source, the support rod is fixed together with the base plate through fixing bolts, and the above equipment modules are placed in a light-shielding casing.

[0043] The mechanical structure includes a base plate, a vertical support rod, a fixing bolt, a converter, a camera clamp 9, an adapter, a light source clamp, and a light-shielding shell; the mechanical structure adopts a support rod and a converter to adjust the vertical position and a horizontal position of the visible light polarization camera, the infrared polarization camera, the spectroscope and the light source; the camera is connected to the support rod through the camera clamp 9 and the converter; the camera clamp 9 can realize the movement of the camera in another horizontal direction; the spectroscope is connected to the fixing rod through the adapter and the converter; the light source is connected to the support rod through the light source clamp, the converter and the support rod; and the light source clamp can realize the angle adjustment of the light source in the range of 0-90 degrees; the support rod is connected to the base plate through a fixing bolt; the two support rods can be spliced ​​to expand the vertical adjustment range of the overall equipment; and the device can be disassembled for easy carrying.

[0044] The present invention proposes a PCB board defect image acquisition device based on dual-band polarization imaging, and the device includes a mechanical structure, an image acquisition module and a light source module. The image of the bare PCB board is acquired by a visible light polarization camera and an infrared polarization camera. Through a spectroscope, the two cameras can acquire intensity images and polarization images of visible light and long-wave infrared bands in the same scene. The device of the invention is reasonably designed, has good image acquisition stability, can provide multi-source image information, is small in size and low in cost, is easy to adjust, and is easy to configure in various production environments.

[0045] The image acquisition method of the PCB board defect image acquisition device based on dual-band polarization imaging of the present invention is as follows:

[0046] S1, adjusting the vertical and horizontal positions of the light source 4, the visible light polarization camera 1, the infrared polarization camera 2, and the beam splitter 3 through the converter 8, and the camera fixture 9 fine-tuning the horizontal positions of the visible light polarization camera 1 and the infrared polarization camera 2, so that the centers of the visible light polarization camera 1 and the beam splitter 3 are on the same vertical line, the centers of the infrared polarization camera 2 and the beam splitter 3 are on the same horizontal line, and the light sources 4 are equidistantly distributed on both sides of the camera;

[0047] Turn on the light source 4, adjust the irradiation angle of the light source 4, and adjust the brightness of the light source 4 through the light source controller 12 to configure a low-angle lighting environment;

[0048] S2, turn on the visible light polarization camera 1 and the infrared polarization camera 2, open the acquisition software of the two cameras, and adjust the focal length and aperture size of the camera according to the clarity of the image;

[0049] S3, place the printed PCB to be inspected at the center of the bottom plate 5, and further fine-tune the positions of the light source 4 and the two cameras according to the preview image, so that the printed PCB to be inspected is imaged at the center of the camera. Adjust the frame rate of the camera as needed to collect, process or store the image.

[0050] The visible light polarization camera 1 and the infrared polarization camera 2 are placed as close to the adapter 10 as possible to ensure that the field of view of the two cameras only includes the printed PCB board to be inspected.

[0051] Example

[0052] See also Figure 1-Figure 3 The present invention provides a technical solution: a PCB board defect image acquisition device based on dual-band polarization imaging. The visible light polarization camera 1 and the infrared polarization camera 2 are fixed on the support rod 6 through the camera clamp 9 and the converter 8, the spectroscope 3 is fixed on the support rod 6 through the adapter 10 and the converter 8, the light source 4 is fixed on the support rod 6 through the light source clamp 11 and the converter 8, the light source controller 12 is connected to the light source 4, the support rod 6 is fixed together with the base plate 5 through the fixing bolts 7, and the above-mentioned equipment module is placed in a light-shielding housing 13 and placed on an optical platform. The visible light polarization camera 1 and the infrared polarization camera 2, the light source 4 and the support rod 6 are connected together, and can be moved vertically and horizontally through the converter 8, and the angle and brightness of the light source can be adjusted through the light source clamp 11 and the light source controller 12.

[0053] The mechanical structure includes a base plate 5, a support rod 6, a fixing bolt 7, a converter 8, a camera clamp 9, an adapter 10, a light source clamp 11, and a light shielding shell 13; the mechanical structure adopts the support rod 6 and the converter 8 to adjust the vertical position and the horizontal position of the visible light polarization camera 1, the infrared polarization camera 2, the spectroscope 3 and the light source 4. The cameras 1 and 2 are connected to the support rod 6 through the camera clamp 9, the converter 8, and the camera clamp 9 can realize the horizontal movement of the camera in another direction. The spectroscope 3 is connected to the support rod 6 through the adapter 10 and the converter 8. The light source 4 is connected to the support rod 6 through the light source clamp 11, the converter 8, and the support rod 6. At the same time, the light source clamp 11 can realize the angle adjustment of the light source by 0-90 degrees; the support rod 6 is connected to the base plate 5 through the fixing bolt 7, and the two support rods can be spliced ​​to expand the vertical adjustment range of the overall equipment. It can be disassembled for easy carrying.

[0054] The image acquisition module includes a visible light polarization camera 1, an infrared polarization camera 2, and a spectroscope 3; the spectroscope 3 can transmit visible light and reflect infrared light, and the visible light polarization camera 1 can simultaneously acquire a visible light intensity image and a visible light polarization image, and the infrared polarization camera 2 can simultaneously acquire an infrared intensity image and an infrared polarization image; wherein the visible light polarization camera 1 is a Sony IMX250MZR, integrated with 0°, 45°, 90°, and 135° polarization filters, with a resolution of 2048x2448 and an adjustable frame rate; the infrared polarization camera 2 has an imaging band of 8-14 microns, integrated with 0°, 45°, 90°, and 135° polarization filters, with a resolution of 512x640; the spectroscope 3 has a size of 2 inches, reflects an infrared band of 8-12 microns, with a reflectivity of 95%, and transmits a visible light band of 400-700 nanometers, with a transmittance of 70%.

[0055] The light source module includes a light source 4 and a light source controller 12; the light source 4 is fixed to the support rod 6 through a light source clamp 11 and a converter 8, the distance and lighting angle between the light source 4 and the printed PCB board are adjusted through the light source clamp 11 and the converter 8, and the brightness of the light source 4 is adjusted through the light source controller 12, wherein the light source 4 is white light with a color temperature of 6500K, and the controller 12 can perform three levels of brightness adjustment.

[0056] Aiming at the situation that the existing detection based on visible light intensity image may misdetect or miss some defects, such as tiny burrs, open circuits and short circuits with small color difference between the circuit and the baseboard, and difficult-to-identify virtual solder holes, the acquisition device can collect intensity images and polarization images of visible light and infrared bands of the bare PCB board at the same time through a dual-band spectroscopic optical path and an integrated polarization camera, and obtain infrared intensity and polarization images of the defective parts containing information such as thermal radiation, material, and surface normal. This effectively solves the problems of low detection accuracy and image quality being easily affected by ambient light caused by the single information source of the existing acquisition device based on visible light, and can provide a solid foundation for multi-source information fusion detection and improving detection performance.

[0057] Since the visible light and infrared information generated by the reflection and radiation of objects are complementary, for example, when the grayscale difference is small, the defect is reflected in the infrared image due to the different radiation amount from other parts around it. Therefore, the visible light and infrared cameras can be used to jointly image the printed PCB board to enrich the characteristics of the measured target and improve the accuracy of detection. At the same time, in the process of reflection and radiation, objects will produce polarization characteristics determined by their own properties. The bottom plate and wiring of the printed PCB board are plastic and metal respectively, and the surface distribution is different. Using the difference in material and surface distribution to obtain the polarization characteristics of the printed PCB board can provide it with information that cannot be obtained by traditional intensity methods.

Claims

1. A PCB board defect image acquisition device based on dual-band polarization imaging, characterized in that: It comprises a light-shielding housing (13), and an image acquisition module and an adjustment frame located therein; The image acquisition module specifically includes: An adapter (10) comprising a horizontal top surface and a 45° inclined side surface, wherein the horizontal top surface is provided with a through hole; a beam splitter (3) mounted on the inclined side surface of the adapter (10); a visible light polarization camera (1), located above the horizontal top surface, with its lens facing downward and its optical center coaxial with the through hole; an infrared polarization camera (2), arranged horizontally on the side of the adapter (10), with its lens facing the beam splitter (3), and its optical center being coaxial with the beam splitter (3); A bottom plate (5), located below the adapter (10), and used for placing the printed PCB to be tested; The adjusting frame specifically comprises: three adjustment devices, respectively connected to the adapter (10), the visible light polarization camera (1) and the infrared polarization camera (2), and respectively used to adjust the heights of the adapter (10), the visible light polarization camera (1) and the infrared polarization camera (2), as well as the angles between them; The beam splitter is used to enable the visible light polarization camera (1) and the infrared polarization camera (2) to simultaneously collect intensity images and polarization images of the printed PCB board to be inspected in the visible light and infrared bands; It also includes an illumination device, comprising two light sources (4) arranged in parallel and opposite to each other, the two light sources (4) being located between the adapter (10) and the base plate (5) and being equidistantly distributed on both sides of the visible light polarization camera (1) and the infrared polarization camera (2), and being used to provide sufficient brightness for the printed PCB board to be inspected.

2. A PCB board defect image acquisition device based on dual-band polarization imaging as claimed in claim 1, characterized in that: The regulating device specifically comprises: Two support rods (6) are vertically arranged on the base plate (5); the visible light polarization camera (1) and the adapter (10) are respectively mounted on the same support rod (6) via a detachable connection device; and the infrared polarization camera (2) is mounted on the other support rod (6) via a detachable connection device.

3. A PCB board defect image acquisition device based on dual-band polarization imaging as claimed in claim 2, characterized in that: The three connecting devices each comprise a camera fixture (9) and a converter (8); one end of each camera fixture (9) is respectively fixedly connected to one side of the visible light polarization camera (1), the infrared polarization camera (2) and the adapter (10); and the other end of each camera fixture (9) is mounted on the support rod (6) via the converter (8).

4. A PCB board defect image acquisition device based on dual-band polarization imaging as described in claim 2 or 3, characterized in that: The lighting device is installed on any one of the support rods (6) via a converter (8).

5. The PCB board defect image acquisition device based on dual-band polarization imaging as claimed in claim 1, characterized in that: The lighting device is connected to a light source controller (12).

6. A collection method of a PCB board defect image collection device based on dual-band polarization imaging, characterized in that: A PCB board defect image acquisition device based on dual-band polarization imaging according to any one of claims 1 to 5, comprising the following contents: S1, adjusting the vertical and horizontal positions of the light source (4), the visible light polarization camera (1), the infrared polarization camera (2), and the beam splitter (3) through the converter (8), and the camera fixture (9) fine-tuning the horizontal positions of the visible light polarization camera (1) and the infrared polarization camera (2), so that the centers of the visible light polarization camera (1) and the beam splitter (3) are on the same vertical line, the centers of the infrared polarization camera (2) and the beam splitter (3) are on the same horizontal line, and the light source (4) is equidistantly distributed on both sides of the camera; S2, adjusting the illumination angle of the light source (4), adjusting the brightness of the light source (4) through the light source controller (12), and configuring a low-angle lighting environment; adjusting the focal length and aperture size of the two cameras; S3, placing the printed PCB to be inspected at the center of the bottom plate (5), and fine-tuning the positions of the light source (4) and the two cameras according to the preview image so that the printed PCB to be inspected is imaged at the center of the camera, and obtaining a visible light intensity image, a visible light polarization image, an infrared intensity image, and an infrared polarization image of the printed PCB to be inspected through the two cameras.

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