A Vision System With 1-inch 17-Mpixel 1000-fps Block-Controlled Coded-Exposure Stacked-CMOS Image Sensor for Computational Imaging and Adaptive Dynamic Range Control

Abstract

This study introduces a vision system that can acquire images at high speeds and high resolutions. Image sensors are used not only in digital still cameras but also in various applications that require capturing wide luminance differences beyond human perception. For example, fast, high-resolution object recognition, and motion tracking in automatic driving systems are essential, particularly in dark tunnels or the mid-summer sunshine. However, the resolution, frame rate, pixel size, and dynamic range should be traded off to achieve a high performance in capturing moving objects with a high contrast. We have developed a high-speed vision system with a readout operation of 1000 fps, resolution of 4K <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\times }\,4\text{K}$ </tex-math></inline-formula> , dynamic range of 110 dB, and fine pixels of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.7~{\mu }\text{m}$ </tex-math></inline-formula> . These characteristics were achieved using several technologies such as 1) coded exposure (CE), which divides the image plane into smaller blocks and controls the exposure time of each block individually, 2) arrangement of analog-to-digital converters in parallel for each block, and 3) three-dimensional wafer stacking, which enables high-density integration of circuits and pixels. The proposed system can be applied in CE-based computational imaging in addition to high-dynamic-range applications for handling both the dark and bright areas in a scene.