Wide dynamic range, high-speed machine vision with a 2×256 pixel temporal contrast vision sensor

Abstract

This paper presents a 2times256 pixel dual-line temporal contrast vision sensor and the use of this sensor in exemplary high-speed machine vision applications over a wide range of target illumination. The sensor combines an asynchronous, data-driven pixel circuit with an on-chip precision time-stamp generator and a 3-stage pipelined synchronous bus-arbiter. With a temporal resolution of down to 100ns, corresponding to a line rate of 10MHz, the sensor is ideal for high-speed machine vision tasks that do not rely on conventional image data. The output data rate depends on the dynamic contents of the target scene and is typically orders of magnitude lower than equivalent data output produced by conventional clocked line sensors in this type of applications. 120dB dynamic range makes high-speed operation possible at low lighting levels or uncontrolled lighting conditions. The sensor features two parallel pixel lines with a line separation of 250mum and a pixel pitch of 15mum. A prototype was fabricated in a standard 0.35mum CMOS technology. Results on high-speed edge angle resolution and edge gradient extraction as well as wide dynamic range operation are presented.