Abstract
A navigation system was installed in many cars, and a large amount of information came to be offered to drivers in recent years. However, characters and symbols on the display are not easy for the aged to see because of a reduction in visual functions. We have proposed a method of deciding an appropriate character size not only for the youth but also for the elderly. This method uses the relation between the static visual acuity and the viewing distance by age. In addition, this method is based on the relation between the accommodation time and the age. In this method, a minimum character size is decided in which drivers are able to read the characters and symbols in a short gaze time while driving. An evaluation experiment has showed that this method is very effective to improve the display visibility including the elderly.
