Three silicon retinas for simple consumer applications

This paper describes three silicon retina chips which are each specialized to measure a different quality of a changing scene. The first retina detects image change anywhere in its field of view, and is intended as a presence detector. The second retina detects a blob of motion moving in one direction, and is intended for automatic door openers. The third retina measures image sharpness, and is intended for use in autofocus systems. All three chips use the same circuit elements. The differences between the chips lie in their architecture. The basic circuit elements I use are an adaptive photoreceptor and a dissimilarity circuit ‐ the “bump” circuit. I like to call these chips “pseudo products.” There is no specific customer in mind, but I did have practical applications in mind that I knew how to do, efficiently and robustly, with minimal power, area, or chip complexity. These chips consume on the order of 100μA (they run for more than a month continuously on a 9V battery), have on-chip bias generators, and are all fabricated as MOSIS 8 TinyChips (2.2mm) 2 in an ancient 2μm or 1.2μm process. The chips also have microcontroller-compatible logic or pulse frequency modulated outputs. In large volume, together with a single-element molded plastic lens, the system costs would be around a dollar. THE CHIP ARCHITECTURES