CHARACTERISTICS OF LETTERS AND LEGIBILITY OF INTERNALLY ILLUMINATED SIGNS FOR THE VISUALLY IMPAIRED

摘要

Internally illuminated signs have potential to improve legibility of directional signs for the visually impaired. This study investigated the relationship between two characteristics of letters - stroke width and depth - and legibility of positive contrast signs. Letters used for the experiments had two stroke widths: light and bold stroke; and three types of depths: flat, raised, and engraved letters. Participants included thirty-six people with moderate visual impairments and, as a control group, twenty people with normal vision. Their subjective ratings of legibility, perceived brightness and glare were compared and evaluated. The results indeed emphasize the importance of the nature of visual impairments. In particular, most participants with glare and light scattering problems found the light stroke letters more legible than the bold ones. For those with blur and double-image problems, the flat and engraved letters were rated much more legible than the raised letter.