Mobile phone camera wide dynamic technology

WDR requires the use of fast-reading CMOS image sensors. With CCD image sensors, users are restricted to use continuous 1 / 60s or 2x 1 / 30s parity field synthesis. In the new technology with wide dynamic range, users can take a long exposure of 1 / 30s image, use a short exposure of 1 / 30s image, and then process the two images in real time to obtain an industrial-level wide dynamic range Image.

The following is an illustration:

There are also companies developing different methods to obtain HDR. Among them, there is a technology called dynamic response pixels. This technology focuses on the DR inside the image, that is, different sensitivity is added to each pixel. The principle of this pixel is to have a large charging capacitor.

When the image is highlighted, the DCG switch is turned on and connected to the physical capacitance of the FD node. In this way, the large-capacity capacitor of the FD node enables the LCG mode, that is, it can hold a large amount of signal charging (not to overflow). Under low illumination conditions, the DCG switch is turned off, disconnecting the capacitor connected to the FD node, enabling the HCG mode, that is, using the extra analog gain inside the pixel. In this case, the FD capacitance depends only on the PN junction capacitance and metal mutual coupling capacitance of the FD, and this value will be much smaller than the physical capacitance structure. Less FD capacitance results in improved conversion gain, improved sensitivity and reduced read noise, at the expense of lowering the maximum charge holding capacitance.