Readability of Character Size for Car Navigation Systems

An experimental examination of the readability of a car-navigation system by elderly, middle-aged and young people was conducted. Subjects (127 people: 19-76 years of age) evaluated ease of reading of displayed characters. The experiment evaluated characters displayed on a liquid crystal display (LCD) similar to those used in car-navigation systems, and evaluated subjective evaluation of readability in 9 stages. Traffic terms were shown in 5 character sizes (2 mm, 4 mm, 6 mm, 8 mm, and 10 mm height) and two languages (Japanese and English) in the experiment. The experiment was conducted with the LCD in two positions: frontal position of the subject and left diagonal position (about 30 degrees). The results showed that the frontal position was significantly more readable than the left diagonal position. The subjective evaluation of readability included both Japanese and English characters. This result shows that English characters were more readable than Japanese ones. The values from the self-rated evaluation of readability were examined using a two-way analysis of variance (ANOVA), and the results showed a significant difference in readability between character sizes. In addition, significant differences were seen between the age groups in the readability of characters in the left diagonal position.