Everyone in the vision industry knows that good lighting is a key element for any machine vision application. It is often the only guarantee of a stable image, and this is especially true when production reaches high speed.
On a high speed production line, the pace at which the products slide past the operator are so high that the human eye is unable to see each and every product.
This is often the case in the continuous process industries (paper industry, production of plastic films, metal sheets), or on the production lines of consumer products like beverage bottles or foodstuff packaging – as shown in the videoÂ above.
Whenever Optical Quality Control is used on this type of production line, the number one concern is getting a stable image with neat outlines. The parameters that must be addressed include:
â€¢ Motion blur
â€¢ Depth of Field
These issues create a complex web of interlinked factors. Adjusting one image parameter can impact negatively on another. For example, to avoid motion blur, we can lower the exposure time. But by lowering the exposure time, the quantity of light reaching the camera is reduced. To compensate, we then have to increase the aperture, which in turn lowers the depth of field – making it even harder to get a clean and neat image of the products sliding on the production lineâ€¦
How do we untangle this complex web? The solution is to increase the power and the quality of the illumination. Each issue can then be worked on independently because, due the increased light, the individual adjustments on longer have a negative knock on effect.
By choosing to install powerful lights to a workstation, you remove the inherent limitations on the smart camera. Powerful lights mean you can both lower the exposure and reduce the aperture, giving an increased depth of field. The consequence of this is that you have more room for your smart camera to get a clearer image that the computer can work with.
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