Light source: as with the illumination factor of the vision sensor, it is an important factor affecting the input of the machine vision system, which directly affects the quality of the input data and the application effect. For each specific application example, to choose the appropriate lighting device to achieve the best results. Its light sources can be categorized into visible and invisible light. A few commonly used visible light sources are white flag lamps, fluorescent lamps, mercury lamps and sodium lamps. On the other hand, the ambient light may affect the quality of the image, so the PC-based solution can be used mainly for electronic production test equipment, which has the advantages of high performance, high flexibility and cost-effective, and is very suitable for difficult, high-resolution and high-speed machine vision applications. So the method of adding protective screen can be used to reduce the impact of ambient light. The lighting system can be categorized according to its irradiation method: backward illumination, forward illumination, structured light and stroboscopic illumination. Among them, backward illumination is the object to be measured is placed between the light source and the camera, and its advantage is that it can obtain high-contrast images. Forward illumination is that the light source and the camera are located on the same side of the subject, and this method is easy to install. Structured light illumination is to project a grating or a line light source, etc. onto the DUT, and demodulate the three-dimensional information of the DUT according to the aberrations they produce. Strobe lighting is a high-frequency light pulse irradiated on the object, the camera shooting requirements and light source synchronization.
Lens: Lens selection should pay attention to the focal length, target height, image height, magnification, the distance from the image to the target, the center point / node and distortion.
Camera: according to different standards can be divided into standard resolution digital cameras and analog cameras. According to different practical applications to choose a different camera and high-resolution camera: line scanning CCD and surface array CCD; monochrome camera and color camera.
Image capture card: image capture card is only a complete machine vision system of a component, but it plays a very important role. Image acquisition card directly determines the camera interface: black and white, color, analog, digital, etc.. More typical are PCI or AGP-compatible capture cards that can quickly transfer images to computer memory for processing. Some capture cards have built-in multiplexing switches. For example, eight different cameras can be connected and the capture card can be told to use the information captured by that one camera. Some capture cards have built-in digital inputs to trigger the capture card to capture, and the digital output port triggers the gate when the capture card captures an image.
Vision processor: vision processor set capture card and processor in one. In the past, when the computer is slow, the vision processor is used to speed up the visual processing task. Now since capture cards can transfer images to memory quickly and computers are much faster, vision processors are used less now.
Working process: the output of the vision system is not an image video signal, but the results of the inspection (such as dimensional data) after computing and processing. Usually, machine vision testing is to use the machine instead of the naked eye to do the measurement and judgment. First, a CCD camera is used to convert the target into an image signal, which is transmitted to a dedicated image processing system and converted into a digital signal based on pixel distribution and information such as brightness and color. The image system performs various operations on these signals to extract the characteristics of the target, such as: area, length, number, position, etc.. Finally, the results are output according to preset tolerances and other conditions, such as: size, angle, offset, number, pass/fail, presence/absence, and so on.