Means of improving LCD instrument panel legibility, and several important factors which must be taken into consideration to achieve this, are described.
Legibility is thoroughly investigated by means of a refined contrast ratio relation.
The relationship between the background brightness and the display brightness required to allow the viewer to recognize the symbols displayed was obtained experimentally in order to determine the optimum contrast ratio for the display.
For designing an LCD instrument panel with improved legibility, the following factors must be taken into account: making the contrast ratio nearly constant beyond a certain level, avoiding undesirable surface reflection from the display, and insuring a minimum brightness level.