Abstract

This paper summarizes three human factors evaluations of lightpoint quality for fixed matrix displays. Lightpoint quality was evaluated as a function of four practical design variables: lightpoint width and motion and display pitch and fill factor. The results showed that all of these variables except fill factor had strong and statistically reliable effects on lightpoint quality.

The last evaluation employed both the FAA/JAA “lightpoint size” and “Vernier resolution” tests. Results indicate a display pitch that just barely passes the lightpoint size test will clearly pass the Vernier resolution test, indicating resolution is mediated by the lightpoint size test. These evaluations reveal enough ambiguity in the FAA/JAA lightpoint size test that the 5th percentile observer may accept a pixel pitch that is 40% larger than the pitch accepted by the 95th percentile observer. A 40% difference in pitch translates into a 2:1 difference in the number of pixels, projectors, IG channels, and thus $ required for the display system. Several means of reducing this variance are proposed.