How does CCD industrial camera realize photoelectric conversion?

Industrial cameras are CCD cameras and CMOS cameras respectively. Currently, CCD cameras that are commonly used for digital image processing generally consist of two parts: an image acquisition unit and an image output unit. So how does a CCD industrial camera achieve photoelectric conversion?
As shown in the figure below, it can be likened to pouring water into a well or bucket. Therefore, the concept of "potential well" is used in semiconductor physics to describe the integrated area used to collect light-excited charges. The maximum photocharge that a single pixel can store is capacity (without overflow to its neighboring pixels), also known as "full well capacity". There is a good linear relationship between the photons collected by the CCD's photosensitive unit and the number of electrons generated. Generally speaking, 2 photons generate one electron, and 50,000 electrons in the output unit generate a 1-volt video signal with a gain of 1:1.
Undesirable noise occurs due to thermal effects that generate additional photons, known as dark current. Therefore, the non-stable structure of the CCD chip does not require lighting. An ordinary CCD can be completely filled with electrons within one minute even at room temperature. Moreover, for every 7 degrees Celsius increase in temperature, the dark current will double, which means that the chip As the temperature rises, the noise increases dramatically. Therefore, in order to control dark current, it is very important to control a relatively short exposure time.

                                                                                                                            CCD光电转化示意图

CCD photoelectric conversion schematic diagram
The method of controlling exposure time is to use a mechanical shutter, but nowadays CCD chips mostly use electronic exposure control, that is, electronic shutter. In manual operation mode, users can usually choose some discrete shutter speeds (integration time) such as 1/50, 1/100, and 1/500 seconds; while in automatic electronic shutter mode, the shutter speed can be automatically adjusted according to the intensity of incident light. If the light intensity is too weak, the weak CCD signal can be enhanced by long integration time mode or by controlling the gain.