Led-type vehicular lamp having uniform brightness

• US 20030169600A1
• Filed: 09/17/2002
• Published: 09/11/2003
• Est. Priority Date: 09/20/2001
• Status: Active Grant

• Current Assignee: Koito Manufacturing Company Limited
• Original Assignee: Koito Manufacturing Company Limited
• Inventors: Amano, Yasuyuki
• Granted Patent: US 6,805,476 B2
• Time in Patent Office: Days
• US Class Current: 362/545
• CPC Class Codes: B60Q 1/2696 Mounting of devices using LEDs
• CPC Class Codes: F21S 43/14 Light emitting diodes [LED]
• CPC Class Codes: F21S 43/40 characterised by the combination of reflectors and refractors

Abstract

A vehicular lamp which radiates light emitted by LED light sources through indirect illumination and which has uniform brightness. Light emitted from the LED light sources is directed upward and formed into parallel beams by Fresnel lenses, and the parallel beams are reflected by a reflector in a frontward direction of the lamp. The reflector is divided into sub reflectors that differ in height and angle of forward inclination according to the areas on which the parallel light beams impinge. The distance between each of the LED light sources and the corresponding one of the Fresnel lenses increases in proportion to a decrease in the height of the corresponding one of the sub reflectors, and the intensity of the luminous flux impinging on each of the Fresnel lenses decreases in proportion to the decrease in the height of the corresponding one of the sub reflectors. Hence, the intensity of the luminous flux impinging on the reflecting surface of each of the sub reflectors decreases in proportion to the decrease in the projected area in the forward direction of the lamp, and thus the sub reflectors have a uniform luminance and the entire reflecting surface of the reflector appears uniform in brightness.

Claims

1. A vehicular lamp comprising:

a plurality of LED light sources;

a plurality of lenses for forming parallel light beams from light from corresponding ones of said LED light sources, said lenses being disposed such that said parallel light beams are directed in the same direction;

a reflector for reflecting said parallel light beams from said lenses in a forward direction of said lamp, said reflector being divided into a plurality of sub reflectors arranged parallel to one another and according to areas on which the parallel light beams from said lenses impinge, a length of said sub reflectors with respect to a direction of radiation of said parallel light beams from said lenses decreasing stepwise from one side of said reflector to the opposite side of said reflector, an angle of inclination of each of said sub reflectors with respect to said forward direction of said lamp increasing in proportion to a decrease in length of the sub reflector in the direction of radiation of said parallel light beams with respect to an adjacent one of said sub reflector, and a distance between each of said LED light sources and the corresponding one of said lenses increasing stepwise in proportion to said decrease in length of the corresponding one of said sub reflectors in said direction of radiation of said parallel light beams; and

a translucent cover disposed on a front side of said reflector.

2. The vehicular lamp according to claim 1, wherein widths of each of said sub reflectors and corresponding ones of said lenses in a direction perpendicular to a longitudinal direction of said lamp increase stepwise in proportion to said decrease in length of said sub reflector in said direction of radiation of said parallel light beams.

3. The vehicular lamp according to claim 1, wherein a reflecting surface of each of said sub reflectors is divided into a plurality of segments extending in the direction of radiation of said parallel light beams, each of said segments comprising a reflecting element and a step portion, whereby each of said sub reflectors is formed in a stepped configuration.

4. The vehicular lamp according to claim 3, wherein each of said reflecting elements comprises a curved surface that diffusively reflects parallel light in vertical and lateral directions.

5. The vehicular lamp according to claim 3, wherein each of said reflecting elements comprises a curved surface that diffusively reflects parallel light in one of vertical and lateral directions, and further comprising lensing formed on said translucent cover for diffusing said light in the other of said vertical and lateral directions.

6. The vehicular lamp according to claim 3, wherein each of said reflecting elements comprises a flat surface, and further comprising lensing formed on said translucent cover for diffusing said light in vertical and lateral directions.

7. The vehicular lamp according to claim 1, wherein said lenses increase stepwise in lateral width from said one side of said reflector to the opposite side of said reflector.

8. The vehicular lamp according to claim 7, wherein said lenses are equal in aperture angle.

9. The vehicular lamp according to claim 3, wherein each of said sub reflectors has the same number of said segments, a length of said step portions of said sub reflectors decreasing stepwise with respect to a direction of radiation of said parallel light beams from said lenses from said one side of said reflector to said opposite side of said reflector.

10. The vehicular lamp according to claim 3, wherein all of said segments of all of said sub reflectors are of an equal length, a number of said segments decreasing with respect to a direction of radiation of said parallel light beams from said lenses decreasing stepwise from said one side of said reflector to said opposite side of said reflector.

18. The vehicular lamp according to claim 3, wherein all of said segments of all of said sub reflectors are of an equal length, a number of said segments decreasing with respect to a direction of radiation of said parallel light beams from said lenses decreasing stepwise from said one side of said reflector to said opposite side of said reflector.

11. A vehicular lamp comprising:

a plurality of LED light sources;

a plurality of lenses for forming parallel light beams from light from corresponding ones of said LED light sources, said lenses being disposed such that said parallel light beams are directed in the same direction;

a reflector for reflecting said parallel light beams from said lenses in a forward direction of said lamp, said reflector being divided into a plurality of sub reflectors arranged parallel to one another and according,to areas on which the parallel light beams from said lenses impinge, a length of said sub reflectors with respect to a direction of radiation of said parallel light beams from said lenses decreasing stepwise from one side of said reflector to the opposite side of said reflector, an angle of inclination of each of said sub reflectors with respect to said forward direction of said lamp increasing stepwise from said one side of said reflector to said opposite side of said reflector, and a distance between each of said LED light sources and the corresponding one of said lenses increasing stepwise from said one side of said reflector to said opposite side of said reflector such that said reflector appears of substantially uniform brightness when viewed from a position in front of said lamp; and

a translucent cover disposed on a front side of said reflector.

12. The vehicular lamp according to claim 11, wherein widths of each of said sub reflectors and corresponding ones of said lenses in a direction perpendicular to a longitudinal direction of said lamp increase stepwise in proportion to a decrease in length of said sub reflector in said direction of radiation of said parallel light beams.

13. The vehicular lamp according to claim 11, wherein a reflecting surface of each of said sub reflectors is divided into a plurality of segments extending in the direction of radiation of said parallel light beams, each of said segments comprising a reflecting element and a step portion, whereby each of said sub reflectors is formed in a stepped configuration.

14. The vehicular lamp according to claim 13, wherein each of said reflecting elements comprises a curved surface that diffusively reflects parallel light in vertical and lateral directions.

15. The vehicular lamp according to claim 13, wherein each of said reflecting elements comprises a curved surface that diffusively reflects parallel light in one of vertical and lateral directions, and further comprising lensing formed on said translucent cover for diffusing said light in the other of said vertical and lateral directions.

16. The vehicular lamp according to claim 13, wherein each of said reflecting elements comprises a flat surface, and further comprising lensing formed on said translucent cover for diffusing said light in vertical and lateral directions.

17. The vehicular lamp according to claim 13, wherein each of said sub reflectors has the same number of said segments, a length of said step portions of said sub reflectors decreasing stepwise with respect to a direction of radiation of said parallel light beams from said lenses from said one side of said reflector to said opposite side of said reflector.