Abstract
This work examined the method used in the American National Standard for Human Factors Engineering of Visual Display Terminal Workstations (ANSI/HFS 100–1988) to evaluate flicker from Cathode Ray Tube (CRT) displays. The standard specifies that “the display must be found to be flicker free for at least 90 percent of a sample of the user population under conditions representative of actual use.” However, the associated flicker compliance test is questioned as not representing realistic office viewing conditions.
A psychophysical experiment was conducted to compare the detection of CRT flicker, in terms of Critical Flicker Frequencies (CFFs), under the ANSI/HFS 100–1988 viewing conditions (i.e., 0 and 20 degrees viewing angle, dark ambient, and hyphen-filled, bright-on-dark character screen) with several others, defined by combinations of ambient illuminance, display luminance, display viewing angle, and screen pattern. As expected, the results indicate that these four factors significantly affect CFFs. More importantly, the CFFs obtained under these viewing conditions were higher than those obtained under the ANSI/HFS 100–1988 viewing condition.
The findings of this work indicate that the ANSI/HFS 100–1988 flicker assessment method is too conservative and may not be sufficient to ensure flicker-free viewing of CRT displays under typical office viewing conditions.
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