Patent ID: 7581862

Claim:
Light guide element ( 31 ) whose cross-sectional area continuously widens from a light inlet surface ( 34 ) to a light outlet surface ( 36 ) at least in areas, characterized by the fact that the light guide element ( 31 ) includes at least one area ( 38 ) with a curved directrix ( 37 ), in which the curvature of the directrix ( 37 ) is constant in this area ( 38 ) or in which the curvature of the directrix ( 37 ) diminishes with increasing cross section of light guide element ( 31 ) in this area ( 38 ), that each line that intersects the light inlet surface ( 34 ) penetrates an outer surface ( 33 ) of the light guide element ( 31 ) outside of the light outlet surface ( 36 ) and that the longest surface line ( 39 ) bordering the light guide element ( 31 ) in the curved area ( 38 ) is longer than the difference of pi and double the largest critical angle of total reflection of the material of light guide element ( 31 ) relative to the material or materials of the surroundings ( 1 ) adjacent to the light guide element ( 31 ) divided by the maximal actual curvature of the mentioned surface line ( 39 ) of light guide element ( 31 ).