An article on Industrial Cameras (1)
Industrial cameras have a variety of classification methods, more common: according to the type of sensor chip divided into CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor), according to the output color is divided into black and white and color, according to the arrangement of pixels Divided into line array and area array, according to imaging dimensions can be two-dimensional (2D) and three-dimensional (3D).
Today we discuss two aspects, the differences between industrial cameras and ordinary digital cameras and CCD camera and CMOS camera respectively.
1. Differences between industrial cameras and ordinary digital cameras
(Picture : industry camera and Digital camera)
The main purpose of machine vision is to replace the human eye for measurement and judgment, so industrial cameras are usually installed on the fast-running line of the factory, in some dangerous environments that are not suitable for manual work or where human vision is difficult to meet. Although industrial cameras are similar to ordinary digital cameras in terms of imaging principles, industrial cameras have high image stability, high transmission capability, and high anti-interference ability in order to meet the special needs of industrial inspection, in terms of shooting speed, accuracy, and Reproducibility and other aspects are far superior to ordinary digital cameras, and the price is much higher.
2. CCD camera and CMOS camera
Image sensor is the core sensor of industrial camera. Current image sensor is mainly divided into Charge Coupled Device (CCD) and Complementary Metal Oxide Semiconductor (CMOS). The principle of CCD and CMOS image sensor is similar. Basically, photodiode is used to convert light and electricity to convert images into digital information. Their main difference is in the way digital signals are transmitted. Each pixel (pixel) charge signal in each row of the CCD image sensor is sequentially transferred to the next pixel, outputted by the bottommost portion, and amplified by the amplifier at the edge of the sensor; and in the CMOS image sensor, each The pixel is connected to an amplifier and an analog-to-digital conversion circuit to output the signal in a manner similar to a memory circuit. CCD and CMOS image sensors have different characteristics because of differences in structure and working principle. CCD image sensors are superior to CMOS image sensors in terms of sensitivity, resolution, and noise control. CMOS image sensors have low cost, low power consumption, and high integration.
With the continuous advancement of CCD and CMOS image sensor manufacturing technology, the difference between the two is gradually narrowing. For example, CCD image sensors continue to reduce power consumption in order to be applied to the mobile communication market. For example, in recent years, CCD-based ToF image sensors have entered the market; CMOS image sensors continue to increase resolution and sensitivity for use in the more advanced imaging products market. Although the industry generally believes that CMOS replacement CCD is an inevitable trend, Sony's main manufacturer of CCD image sensors in Sony (Sony) even released its schedule to terminate mass production of CCD. However, at present, many industrial or professional applications still occupy an important position based on CCD image sensor technology. For a long period of time, the two should be coexisting.
In fact, the biggest advantage of CMOS image sensors is the ability to integrate with image acquisition and signal processing to implement system-on-a-chip (SoC). As machine vision systems move from PC-based board-level vision systems to more functions, smaller With the development of smart camera systems, CMOS image sensors are bound to be the final winner.