Human Factors Evaluation of the Truck Productivity Computer's™ Electroluminescent Display

Electroluminescent (EL) displays are well known for their superior visual performance (brightness and contrast) and environmental performance (durability) characteristics. These characteristics contributed to Freightliner Corporation's selection of Planar Systems, Inc. to build a custom electroluminescent display that measures 80 pixels in height and 320 pixels in width for their Truck Productivity Computer. The Truck Productivity Computer is an open-platform information, communication, and integration system that fits in a standard (DIN 1) radio slot in a truck dashboard.

When compared to most conventional in-vehicle displays, the emissive EL technology offers increased brightness and contrast ratio. Considering these advantages and the type of information to be displayed, traditional human factors display guidelines, based primarily on other display types, were thought to be unsuitable for recommending character height for this display. It was hypothesized that a smaller font may be suitable for this display technology, while not sacrificing the required recognition times necessary for safe operation of the truck. Study 1, as described in this paper, was a human factors investigation to test whether character-size recommendations for conventional displays would apply to the EL display in this specific application. A soft-key label reading test and a subjective evaluation of font size was undertaken. It was found that subjects could read smaller text with an adequate level of accuracy and comfort in an appropriately short period of time. Study 2 was an in-truck validation of the findings of the first study.