Multi-resolution CMOS image sensor with motion detection function and region-of-interest readout

Abstract

A 264 × 272 CMOS image sensor in 0.35μm 1P4M technology with a 8.9μm pixel pitch has been proposed. Using integration ability of CMOS image sensor, four functions as motion detection, region-of-interest readout, multi-resolution readout and mixed-resolution readout are integrated in CMOS image sensor with small pixel size. Proposed sensor outputs four types of image. First, 1-bit motion image is available. By proposed motion detection scheme using inter-pixel switch, 1-bit motion image acquisition without sacrificing pixel size and fill factor is possible. Implemented pixel size is 8.9 μm × 8.9 μm and fill factor is 27%. Second, 10-bit region-of-interest (ROI) image focusing on moving object can be read out with high frame rate. ROI image can be read with 480 fps when ROI size is 128 × 128. Regional controllability is imposed on pixel and periphery circuitry for ROI image readout. ROI image can also be read with reduced resolution by proposed pixel merging scheme. This multi-resolution readout enhances signal-to-noise ratio, sensitivity and bandwidth efficiency. Third, mixed-resolution image can be read out. Reduced resolution image with fast frame rate for fast moving object is output while normal resolution image with normal frame rate for stationary background image outputs. Both images output simultaneously by dual-channel output. This is the first CMOS image sensor which is able to output mixed resolution image. Last, normal high-quality image is available as conventional CMOS image sensor, and multi-resolution readout is also available. Since fast feature extraction without image processor is possible with reduced bandwidth, proposed sensor will be applicable to bandwidth-limited, power-limited applications like sensor network, robotics, real-time control system and so on.