Experiment to select a suitable visual display and evaluate its washout characteristics

Two separate experiments were carried out on a display for a portable microprocessor. Of three phosphorescent displays available for installation, readability times, error rates and subjective preferences were recorded and compared using fifteen subjects. On these measures recorded, the small dot-matrix display (3.5 mm × 5.0 mm) performed better than the large dot-matrix display (5 mm × 8 mm) and considerably better than the segmented display (5 mm × 8 mm). The second experiment set out to quantify the effects of a range of three ambient illuminance levels on the readability of the small dot-matrix display, using the same criteria. Results suggested that for ambient illuminance levels between 0 lux and 15000 lux, a single display intensity was feasible, this being about 40 cdm^?2.