VisionCon2019 in Suzhou!

VisionCon2019 in Suzhou!

Jan 07 2020

Practices from Big shots in Machine Vision Light Industry!

What are the focuses worth viewing of machine vision in the areas of advanced imaging technology and systems and applications? What are the latest products and technical solutions in the industry?

VisionCon 2019 (Suzhou) drew to a successful conclusion on 21st June, many topics aroused heated debate and impact of the conference is still increasing! Today we will have a glance at how Wordop tracking the trend and how they could closely combine their products with characteristics of light source?

Speaker Su Hailong is deputy general manager of Wordop Instrument Co., Ltd. from July 2005 to December 2014. He founded Wordop Automation Technology Co., Ltd with his friend Kang in December 2014 and served as deputy general manager from then on. In 2017, Wordop opened a branch office in Suzhou. It is a manufacturer of machine vision lights and controllers.

A week before the meeting, Su had just discussed the characteristics of light sources with experts from Hangzhou and Zhejiang University. 'The characteristics of light source are much more than what we have discussed today.' Su said modestly: 'I only grope my way through actual practices!' The PPT on-site listed the different characteristics of light sources such as light path, angle, uniformity, spectroscopy, polarization and strobe control. Wordop has a wide range of products that provide customers with more choices.

Light Path:
Direct and Diffused Light

'The textbook only taught us direct light and diffused light, but now our visual environment is much more complicated!' Direct light means the light beads irradiate products directly and suitable for the scene of high directivity requirement. Diffused light means the beads irradiate products indirectly through special material, it can reduce light spot and suitable for the scene of high uniformity requirement.

The PPT on the large-screen showed the effect of different application scenarios, giving us a more direct comparison. For example, for flatness detection of relay pin, the use of direct light source can quickly locate the pin, which is convinient for algorithm processing; for dust detection of LCD surface, it can highlight dust and identify dust quickly.
For another example, the AOI detection of pan-panel uses a custom parallel light source, which can detect concave&convex, creases and other defects. The uniformity of diffused light is very high, which will interfere brightness. However, a more uniform luminous surface of the mirror-reflected material can effectively avoid the bead shadow on the surface of the object under test.

Wordop Products

High parallel line light source can be combined with line-scan camera, using standard molding to ensure structural stability, the uniformity of the light source is up to 90%. It is mainly used for the appearance detection of glass cover plate of mobile phone, AOI detection of LCD substrate glass, AOI detection of PCB bare board, appearance detection of steel/graphite sheet of mobile phone, and appearance detection of membrane materials.

Angle -
Sometimes, the places we need to detect are not the same surface as the places that don't need to be detected, where some places diffuse light while other places is mirror-reflected. At this point, the concept of bright field lighting and dark field lighting needs to be introduced. Bright field illumination is to observe object by direct light, dark field illumination is through reflected light or diffraction of the light, forming two distinct ways of lighting.

There are three typical lighting methods: bright field lighting, dark field lighting and backlighting. When using direct lighting, the materials under test are usually different, resulting in the loss of surface feature information. The backlight can distinguish between transparent and opaque areas, which appear white and black. When using the backlight, the light should be used as parallel as possible to ensure that the light of different intensity does not cause changes of the profile of the object, thereby improving the accuracy of the overall detection.

For mobile phone cover glass screen pre-screen detection, the use of multi-angle light source, can clearly detect scratches and other defects. The principle is that the use of forward dark field lighting, through a number of aspherical reflection of the way to achieve transparent workpiece scratch detection.

Wordop Products

A utility model exterior patent has been applied for. Mainly used in mobile phone glass cover appearance detection, LCD substrate glass AOI detection, PCB bare plate AOI detection, more industry applications are being explored!

Uniformity -

1. Use high uniform backlighting of different sizes, which can be used to detect mura defects of different sizes.
2. Using a high uniform linear light source, you can detect products with high uniformity requirements, and can be backlit imaging.

Wordop Products

High parallel line light source can be combined with line-scan camera, using standard molding to ensure structural stability, the uniformity of the light source is up to 90%. Mainly used in appearance detection of mobile phone glass cover plate, aluminum foil surface scratch detection, steel plate surface detection, etc.

The field display showed that the luminance length is 500mm and the uniformity within 450mm is 90%.

Spectrum -

Complementary colors are the colors that are exactly opposite in the color ring. When you shine a light on an object with complementary colors, the color of the object in the black-and-white camera is close to black. Depending on the color ring, we can achieve the highest level of contrast with the opposite color. For example, when the light is irradiated with cold light, the color will darken, and the color will brighten when the cool light shines on the cool light. When using a color camera, white is usually selected. On-site we also see that for PCB character detection, blue light is fully reflected, the background is white, no characters; Obviously, using a light source of a specific spectrum can increase the contrast of features.
Metal spectre reflectivity. In the field of wavelengths below 600nm, gold and copper have very low specular reflectivity. With wave length (e.g. blue light) LED lighting, the metal image is darker, and the image of the metal surface is relatively bright with the long (e.g. red) LED illumination of the wave length. For example, weld spot detection, the use of blue light source, can improve the contrast of welding points, filter copper wire interference.
Infrared. The use of 1300nm infrared light, the use of infrared penetration strong characteristics, with infrared array camera use, so that the invisible to the naked eye of the fissure becomevisible. Such as the side scratch detection of beverage cans, with ordinary light lighting, pattern interference, with infrared light lighting, long wavelength, through the beverage can surface of the texture. Infrared light ignores the color of the product and the effects of some of its patterns.
Ultraviolet light. For example, anti-counterfeiting label detection, the use of ultraviolet (fluorescent) characteristics, visible anti-counterfeiting labels, the use of ultraviolet light source to detect transparent film, because of the uv light scattering capacity is high, scattered on the surface of the object, can effectively observe the surface of the object, can see the transparent film surface ITO.

Polarization -

Polarizer mirror and polarizing light source, can eliminate the reflective material in one direction of the reflective spot, quickly read information. Therefore, if the product is reflective, the use of polarization light sources may be given priority.
Polarized mirrors can cause 2-3 times the loss of light, so that the camera can not use the high-speed shutter because there is not enough light, in the case of light is slightly inadequate, or even because the camera shakes to take blurry photos. Therefore, polarizing mirror is a good thing, but by no means can always be installed on the lens, we only when necessary will ask it out of the horse!

Strobe control -
High-speed strobe new technology!

Currently, the Wardup controller can be used to control high-speed strobe with peripheral control light sources. In the future direction, the use of intelligent controllers, with the company's high-speed strobe flash source, to achieve high-speed strobe photography.
Compared with the ordinary controller, the brightening module controller can instantly increase the brightness of the light source by more than 3 times, through the external trigger function and high and low level switching, so that the light source flash escent, the light light time can be set at 0-999us.
The highlight of the strobe control is the short response delay! PBT4 strobe time adjustable (0-999us), trigger delay time adjustable (0-999us), light source delay glow time adjustable (0-999us). At the above time, the step is 1us. In addition, external and internal triggers can be triggered externally (frequency 1-20Hz adjustable, not always on, easy to set parameters during debugging, directly for testing). Trigger port, internal use of two-way optical coupling, trigger input, wiring regardless of positive or negative;

"The light of science and technology, create a better future!" "Wordop has the courage to perceive industry challenges, capture industry opportunities, integrate collaboration, work to address key customer needs, continuously build forward-looking light source products and improve light source applicationservices, and broaden the space for future applications of automation equipment."