Patent ID: 8351123

Claim:
Diffractive head up display device comprising a projection unit that projects an image in a direction towards a diffractive combiner to display a virtual image in a field of view of an observer, wherein the projection unit comprises a light source that projects a projection light beam directed along an axis towards a display configured to project the image onto the diffractive combiner, wherein the projection unit comprises a projection mask that defines a projection window positioned between the combiner and the display, wherein the area of the projection window corresponds to a display area of the display, wherein the light beam uniformly illuminates an area of the display larger than the display area defined by the mask, and wherein the display and the mask are movable in a direction substantially normal to the axis of the projection light beam, so that adjustment of the position of the virtual image in the field of view of the observer is obtained by movement of the display and of the mask.