Increases in Hot Pixel Development Rates for Small Digital Pixel Sizes

Abstract

The rising demand for digital imagers has resulted in the push to reduce pixel size while increasing imager sensitivity, which in turn, results in an increasing rate of defects that develop in the field. Research has shown that “Hot Pixels” are the most common type of defects in modern digital imagers, with their number in a given imager increasing over time. In our previous studies we had developed an empirical formula to project the growth rate of hot pixel defects in terms of defects/year/mm2. We discovered that hot pixel densities tend to grow via a power law of the inverse of the pixel size raised to the power of about 3. This paper explores the effects on defect growth rate, of reducing pixel sizes even more, specifically in cell phone imagers. Due to lack of noise suppression algorithms in these imagers, we have developed specialized procedures for analyzing the collected dark frame data. We also ensure that hot pixel detections in cell phone cameras are statistically significant within the error margins. Our current results confirm the accelerated growth rate for this small pixel range, emphasizing the need for caution by designers and further study in this area of defect development.