A stacked event-based vision sensor that reportedly offers the smallest 4.86 μm pixel size available and a high dynamic range (HDR) performance of 124 dB-plus has been engineered by Sony Corporation and France-based Prophesee. The device is suitable for machine vision applications such as detecting fast moving objects in a range of environments and conditions.
The device incorporates features of Sony's stacked complementary metal oxide semiconductor (CMOS) image sensor to realize small pixel size and excellent low light performance. Fast pixel response, high temporal 
Source: Sony Corporationresolution and high throughput data readout are achieved when these features are combined with Metavision event-based vision sensing technologies developed by Prophesee. The stacked event-based vision sensor detects changes in the luminance of each pixel asynchronously and generates coordinates and other data for the pixels where a change is detected.
The upper pixel chip and the logic chip forming the lower layer use signal processing circuits to detect changes in luminance based on an asynchronous delta modulation method are arrayed separately. Aperture ratio is enhanced by up to 77% by placing back-illuminated pixels and a part of N-type MOS transistor on the pixel chip sitting at the top of the stack.
Electrical continuity results from use of connected copper pads when stacking the back-illuminated CMOS upper image sensor section and lower logic circuits. This design enhances performance and allows for the smaller design relative to the use of through-silicon via wiring.
