Lighting device, in particular fog light for motor vehicles
The lighting device, in particular the fog light for motor vehicles comprises a lighting unit for emitting light beams and a lens on which the light beams fall, configured as a Fresnel lens to form light paths in the plane (zy), which is perpendicular to the axis (x) passing through the center of the lens and located at a distance in front of the lens. The lens is not axially symmetrical with respect to the axis (x) and its zones are configured to form a light path whose height (v) is smaller than its width (s).
1. A lighting device for motor vehicles comprising a lighting unit for emitting light rays, a lens on which the light rays fall, configured as a Fresnel lens, to produce a light footprint in an imaging plane (zy), which the imaging plane (zy) is perpendicular to an optical axis (x) passing through the centre of the lens and located at a distance in front of the lens, wherein the lens is not axially symmetrical to the optical axis (x) and comprises zones that are configured to deflect beams of light rays that pass through the lens in a direction from the optical axis (x) so as to form a light footprint from the lens whose height (v) is smaller than its width(s).
2. A lighting device according to claim 1 , wherein the lens is planar.
3. A lighting device according to claim 1 , wherein the lens is symmetrical with respect to a horizontal plane (xy) including the optical axis (x).
4. A lighting device according to claim 1 , wherein the lens is symmetrical with respect to a vertical plane (zx) including the optical axis (x).
5. A lighting device according to claim 1 , wherein the zones of the lens are arranged as rings around a centre of the lens, where each ring farther from the centre of the lens surrounds the rings closer to the centre of the lens, wherein from each pair of the adjacent zones the zone farther away from the centre of the lens is configured to deflect, in a vertical plane (zx), a beam of light rays from a direction of the optical axis (x) at a vertical angle (α) that is greater than or equal to the vertical angle (α) at which, in the vertical plane (zx), the other zone from the pair of the zones is configured to deflect a beam of light rays from the direction of the optical axis (x).
6. A lighting device according to claim 1 , wherein the zones of the lens are arranged as rings around a centre of the lens, where each ring farther from the centre of the lens surrounds the rings closer to the centre of the lens, wherein from each pair of the adjacent zones the zone farther away from the centre of the lens is configured to deflect, in a horizontal plane (xy), a beam of light rays from a direction of the optical axis (x) at a horizontal angle (β) which is greater than or equal to a horizontal angle (β) at which, in the horizontal plane (xy), the other zone from the pair of the zones deflects a beam of light rays from the direction of the optical axis (x).
7. A lighting device according to claim 5 , wherein each zone is configured to deflect a beam of light rays by a horizontal angle (β) that is greater than a vertical angle (α) by which the zone is configured to deflect a beam of light rays.
8. A lighting device according to claim 7 , wherein the horizontal angle (β) is twice the vertical angle (α).
9. A lighting device according to claim 6 , wherein the horizontal angle (β) by which the zone that is the most distant of zones from the centre of the lens deflects a beam of light rays is less than or equal to 20°.
10. A lighting device according to claim 1 , wherein the height (v) of the light footprint is approximately half its width(s).
11. A lighting device according to claim 1 , wherein the lens comprises a central part for directing a beam of light rays in the direction of the optical axis (x).
12. A lighting device according to claim 1 , wherein in a projection into a surface of the lens, each of the zones of the lens is delimited by a ring whose edges are formed by closed curves which are in this projection in each of four parts of the lens made from a first adjacent arc with a first radius (R 1 ), a second arc with a second radius (R 2 ) and a third arc with a third radius (R 3 ), wherein the first radius (R 1 ) is equal to the third radius (R 3 ), and the second radius (R 2 ) is twice the first radius (R 1 ).
13. A lighting device according to claim 12 , wherein for each zone, the first radius (R 1 ) of the zone is equal to two thirds of a distance (a), measured in a horizontal plane (xy), of an edge of the zone from the centre of the lens.