US 7,581,862 B2 · Light guide element and light unit with light guide element

Abstract

The invention concerns a light guide element whose cross-sectional surface widens continuously at least in areas from a light inlet surface to a light outlet surface, as well as a light unit with at least one LED as light source and with a light guide element. For this purpose the light guide element includes at least one area with a curved directrix, in which the curvature of the directrix in this area is constant or which the curvature of the directrix in this area diminishes with increasing cross section of the light guide element. With the present invention the light guide element and a light unit are developed, which permits a soft transition of illumination intensity in a sharply delimited light-dark boundary of the illuminated area on the other edges.

Claims10

Dependent claims

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).

Light unit (10) with a light source (20), which includes at least one LED (21) with at least one light-emitting chip (22), with at least one light guide element (31) continuously widening at least in areas from a light inlet surface (34) to a light outlet surface (36) in the light propagation direction (5) optically connected after light source (20), 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).

Dependencies are inferred from the claim text.

Light guide element and light unit with light guide element

Life of this patent

Light guide element and light unit with light guide element

Life of this patent

Abstract

Claims10