Driver's Ability to Recognize Forward View and Head-Up Display Images in Automotive Application II: Dependency on the depression Angle of Displayed Images@@@表示像位置の高さの影響

Although originally developed for aircraft use, head-up displays have found application automobiles recently. The driver's visual performance can be regarded as double task. One is obtaining information on the objects in the forward view, and the other is recognizing information displays in automobiles. The position of the displayed image, which is mainly determined by distance, depression angle and boldness of the HUD images, is the most important factor in designing better HUDs for automobiles. In a previous paper, we discussed the relation between the distance of the HUD image and task completion. In this paper, how the depression of angie of HUD images affects completion of the task is investigated by the double task method. The task of reading the HUD image rarely affects recognition of the forward view whether the depression angle is large or not. The lager the depression angle becomes, the more difficult it is to recognize the HUD images. However, there is finite optimal range of depression angle, which is approximately from 0 degree to 5 degrees. This paper also discusses how to determine the parameters to design better HUD for automobiles.