Visual perception of HUD (head-up display) image with small angle of depression in practical automotive use

Although HUDs (head-up displays) were originally developed for aircraft use , in the past decade they have found application in automobiles. T he angle of depression of the displayed image is one of the most important parameters for designing automotive HUDs. Generally, drivers can perceive m ore information displayed by HUDs when the angle of depression is smaller. However, it has been observed in experiments that decreasing the angle in a n actual automotive HUD, where the distance to the displayed image is not g reat, can result in misperception of the displayed information. This article describes how the angle of depression affects the driver's per ception of HUD images and the forward view. It also discusses why mispercep tion occurs, what causes it, and how to design HUDs to avoid it, based on e xperimental results derived from an analysis of drivers' eye movements. (C) 1999 Scripta Technica, Electron Comm Jpn Pt 3, 82(4): 1-9, 1999.