Thermal performance for spot lamps
The invention provides a light generating system ( 1000 ) comprising a housing ( 500 ) and a light generating device ( 100 ); wherein the light generating device ( 100 ) comprises an elongated support ( 150 ) and a plurality of light sources ( 10 ), wherein the light sources ( 10 ) comprise solid state light sources supported by the elongated support ( 150 ); wherein the light sources are configured to generate light source light ( 11 ); wherein the housing ( 500 ) is thermally conductive; wherein the housing ( 500 ) comprises a reflective inner surface ( 510 ) comprising a staircase profile ( 520 ) with n stairs ( 521 ), wherein n≥2; wherein the n stairs have a stair length L 1 ; wherein the reflective inner surface ( 510 ) is reflective for the light source light ( 11 ); wherein the light generating device ( 100 ) is mounted on the staircase profile ( 520 ) over at least part of the stair length L 1 and configured in thermal contact with the housing ( 500 ).
1 . A lighting device selected from the group of a lamp and a luminaire, the lighting device comprising:
a light generating system having a housing and a light generating device,
wherein the light generating device has an elongated support and a plurality of LED light sources, the plurality of LED light sources are supported by the elongated support, and the plurality of LED light sources are configured to generate light source light;
wherein the housing is thermally conductive, the housing has a reflective inner surface with a staircase profile with n stairs in which n≥2, at least one of the n stairs has a parabolic shape, at least one of the n stairs is in a plane perpendicular to a lamp axis of the light generating system, each of the n stairs have a stair length L 1 , and the reflective inner surface is reflective for the light source light;
wherein the light generating device is mounted on the staircase profile over at least part of the stair length L 1 and configured in thermal contact with the housing;
wherein the light generating device is configured in physical contact with the reflective inner surface, the housing has a thermally conductive material, the elongated support has a support length L 2 in which 0.5≤L 2 /L 1 ≤1, and the housing has a thermal conductivity selected from the range of ≥0.8 W/(m*K); and
wherein the light generating device has an elongated LED filament, the LED filament has the plurality of LED light sources encapsulated by an encapsulant with a luminescent material therein.
2 . The lighting device according to claim 1 , wherein n is selected from the range of 3-6.
3 . The lighting device according to claim 1 , wherein the elongated support is mechanically attached to the reflective inner surface.
4 . The lighting device according to claim 1 , wherein the reflective inner surface has a reflection for the light source light in the range of R≥85% assuming perpendicular irradiation of the reflective inner surface.
5 . The lighting device according to claim 1 , wherein at least one of the stairs of the staircase profile is tilted relative to a lamp axis of the light generating system.
6 . The lighting device according to claim 1 , wherein the housing comprises a housing wall, wherein the housing wall comprises a material selected from the group comprising aluminum, steel, copper, brass, a polymeric material, a ceramic material, and a 3D printed material.
7 . The lighting device according to claim 1 , wherein the housing comprises a metal.
8 . The lighting device according to claim 1 , wherein the light generating device comprises a first end and a second end; wherein the light generating system comprises an electrical connector for connection with an external source of electrical energy, wherein the first end is configured closer to the electrical connector than the second end; wherein the light generating system comprises electronics configured in the housing; wherein the light generating system further comprises an electrical connection between the electronics and the light generating device, wherein the electrical connection is connected to the light generating device at a position closer to the first end than the second end.
9 . The lighting device according to claim 1 , wherein the staircase profile comprises concentrically configured stairs; wherein the light generating system comprises at least two light generating devices mounted on at least two of concentrically configured stairs.
10 . The lighting device according to claim 8 , wherein the housing comprises a crevice, wherein the crevice comprises the electrical connection; wherein the light generating system comprises at least two light generating devices; and wherein the electrical connection is configured to electrically connect the at least two light generating devices.
11 . The lighting device according to claim 9 , wherein the electronics are configured to individually control the at least two light generating devices.
12 . The lighting device according to claim 1 , wherein the light generating device comprises an elongated printed circuit board.