With the advancement of intelligent technology, camera module related technologies have also made great progress in recent years. As the core component of CCM, CMOS image sensor has entered the era of 200 million pixels. Do you know how CMOS perceives and processes light sources? What are the principles and processes?
Generally, semiconductor image sensors can be divided into two types according to different light sensing mode structures: one is the image processing technology mainly based on camera tubes, such as the imaging technology used behind traditional home TVs; The other is a solid-state image acquisition component represented by CMOS.
When the light passes through the lens, it is correctly projected onto the sensor after the concentrated and corrected refraction of the lens group. The farther the object passes through the lens group, the smaller the field of view of the linear sensor. In contrast, the closer the object is to the sensor, the larger the field of vision will be.
First, the light will be further concentrated and refracted through the CIS micro lens, and then color filtered through the color filter array (CFA). After filtering, the photons will enter the photodiode for optical/electrical conversion.
When a positive voltage is applied to the electrode of the photosensitive module, a positive potential will be generated on the surface of the silicon substrate, which forms a potential well. The greater the positive voltage applied to the electrode, the deeper the potential well and the greater the attraction to electrons.
For example, if the light signal is regarded as a raindrop, the small water basin is regarded as a light sensing element, and the conveyor belt is regarded as a signal transmission gate. Therefore, the potential well is like a basin collecting water. The rainfall (light signal) at each point on the plane is concentrated in the basin. The light signal intensity varies from place to place, and of course, the amount of water carried by each basin is also different. After that, the water basin is transmitted out through the conveyor belt one by one through the translation position, and the optical signal is stored step by step. The above is the general working principle of the image sensor.
At this time, the charge generated by the photon is very small, and the amplifier is required to amplify the signal. After simple processing by the analog processor, the digital/analog conversion, that is, A/D conversion, is performed to convert the analog signal into a digital signal.
At this point, CIS has basically completed the processing of light source. It can be understood that CIS processes light into a digital signal that can be recognized by the machine. Of course, due to the progress of manufacturing process and technology, CIS integration is also getting higher and higher. It is not only simple to process light sources, but also high SOC integration of some image sensors, which can directly correct images.
