Projection unit for a head-up display
View Patent ↗The invention is directed is directed to a projection unit for a head-up display having an image generator, a mirror and a refractive lens which are arranged in a housing one behind the other in the light propagation direction. The beam path is directed to a windshield. Notably the mirror has a concave reflection surface, and the lens has a free-form surface at lease on one of the optically active surfaces (D-U and/or D-O).
1. A projection unit for a head-up display comprising:
an image generator;
a mirror; and
a refractive lens;
said imager generator, mirror and refractive lens being arranged in a housing one behind the other in light propagation direction; and
a beam path of said projection unit being directed to a windshield;
said mirror having a light-bundling reflection surface; and
said lens having a free-form surface at least on one of an optically active surface.
2. The projection unit for a head-up display according to claim 1 , wherein one of the optically active surfaces of the lens has a cylindrical component extending in a direction from the driver to the front-seat passenger.
3. The projection unit for a head-up display according to claim 1 , wherein the lens has a plano-convex to concave-convex cylindrical component.
4. The projection unit for a head-up display according to claim 3 , wherein the surface of the lens facing the windshield has a constant concave radius.
5. The projection unit for a head-up display according to claim 3 , wherein the surface of the lens facing the mirror has a constant convex radius.
6. The projection unit for a head-up display according to claim 1 , wherein the surface of the lens facing the windshield is a concave free-form surface and the surface of the lens facing the mirror is a convex free-form surface.
7. The projection unit or a head-up display according to claim 1 , wherein additional spherical or plane mirrors are arranged between the mirror and the image generator for beam folding and beam shaping.
8. The projection unit for a head-up display according to claim 1 , wherein the lens simultaneously serves as a cover for the opening of the dashboard scoop.
9. The projection unit for a head-up display according to claim 1 , wherein the concave reflection surface of the mirror has a spherical radius.
10. The projection unit for a head-up display according to claim 1 , wherein the concave reflection surface of the mirror is aspheric.