The field of view provided by systems currently in use is inadequate in situations where head-up-displays in large commercial vehicles such as agricultural machinery are intended to support even complex decision making processes by providing visualized data: The reason for this is that the field-of-view in the head-up-displays is angled at only about nine degrees. Consequently, the area onto which the image is projected is not sufficiently large to display the required volume of information on the front windshield of the vehicle. Larger, heavier and, above all, more expensive optics are required in order to expand the field of view. The head-up-displays installed in agricultural vehicles at present already take up a space of between two and six liters. The intention now is to use alternative plastic optics as part of a drive to expand the viewing field without increasing the vehicle cockpit space required by the systems.
Within the framework of the ARHO project, the Fraunhofer IPT is collaborating with its project partners to develop a head-up-display, in which the conventional glass optics will be replaced by polymer Fresnel optics. This will allow the field of view to be extended to 25 degrees. It is anticipated that the weight and size will actually be below those of the head-up-displays currently in use. Plans have been drawn up to produce the lenses in injection molding processes in order to keep the cost of this head-up-display system competitive.
One of the main challenges arising in any operation to produce polymer Fresnel lenses is the need to ensure precision and reproducibility: The intention is to achieve image quality equaling that of conventional glass lenses. The consortium is therefore developing a special replication process for Fresnel lenses and is constructing a complex injection compression molding tool, to be put into operation as part of the project. The quality of the lenses produced via injection compression molding will be assessed using appropriate measurement engineering techniques. On completion of all functional checks, the Swedish partner Optea AB will integrate the optics in a head-up-display system for agricultural machinery.
The project is funded by the Central Innovation Program for SMEs (ZIM) of the German Federal Ministry for Economic Affairs and Energy (BMWi) R & D Collaborative projects (Funding Code: ZF4341807HM8)