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

Abstract

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