Why CMOS image sensors? – Vision Campus

January 4, 2020 posted by


Welcome to our Vision Campus! Today, I would like to talk about CMOS image sensors, their advantages and some of the applications they can be used for. I will also give you some practical examples. There are two types of image sensors: CCD and CMOS. In this video, I will focus on the advantages
of CMOS image sensors. Finding the right sensor for your application depends on the application’s requirements. However, over the last couple of years CMOS image sensors have become more and more popular. This shouldn’t be a surprise, considering
the advantages of the CMOS sensor technology. These advantages are: High frame rate, High resolution, Low power consumption, Improved noise performance, Improved quantum efficiency, A strong dynamic performance and a good price/performance ratio. What do these advantages mean for different applications? Not all CMOS image sensors are the same. Some of them have a larger dynamic range than others. A large dynamic range enables the camera to capture both bright and dark image details. Traffic applications, like speed enforcement, benefit from a large dynamic range. For this application it’s important to have a clear image of both the license plate and the driver. A large dynamic range allows you to depict the details in the bright part of the image just as clearly as in the dark part. A smaller dynamic range would only provide good detail for one of them. Traffic cameras are exposed to bright headlights and glaring sunbeams. With a CCD image sensor, the bright spots in the image can create vertical lines and obstruct the capturing of the license plate. These effects are called blooming and smear. Due to their completely different technological setup, CMOS image sensors don’t have these issues. This makes them a perfect choice for these types of applications. Medical technology is another good example. Long-term availability is a very important
factor in the medical field, since medical devices need to go through a long certification process. Given its position as a newer technology, CMOS technology will remain available in the long run. With their lower power consumption, CMOS image sensors also have lower heat dissipation and therefore good noise performance. This is particularly handy when the camera is permanently operated without a cooling mechanism, such as in lab automation systems,
or in noise-sensitive applications. When analyzing cell cultures with an automated scanner, a high noise level would make it very difficult for the software to tell the cells and the growth medium apart. Here CMOS technology achieves lower noise through lower heat. Remember our cookie inspection example from the “Vision Systems” video? This is one of the many examples, where a CMOS sensor is a good fit. In food inspection, system costs need to be as low as possible. In addition, the better price/performance
ratio of CMOS cameras makes these systems more affordable than comparable systems with CCD sensors. Another good example from the factory market is bottle inspection. A bottle inspection system can have different purposes: you can inspect the fill level, detect foreign particles in a bottle or check the capping. CMOS image sensors continue to be at an advantage here, since the application demands very high frame rates. In most systems, more than 60,000 bottles per hour must be inspected – sometimes even up to 90,000 bottles per hour. These practical examples show that cameras with CMOS image sensors are the optimal choice for many different applications. Thanks for watching!

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