Lighting device comprising LEDs and reflection element

Abstract

A lighting device, wherein the effectivity is increased and allows maintaining a simple manufacturing process, comprises: a housing having a longitudinal direction, the housing comprising: reflective side walls extending in the longitudinal direction, a first cavity disposed between the reflective side walls, and an opening of the first cavity for the passage of light from the first cavity; LEDs, each having a light-emitting face and side faces, wherein the LEDs are arranged on interposers for providing electrical connection of the LEDs, wherein the LEDs are arranged in the first cavity such that the LEDs are at least partially arranged along the longitudinal direction of the housing; and a reflection element that covers a side of the interposers facing the opening, wherein the reflection element surrounds the LEDs on the side faces, and is configured as strip comprising through holes in which the LEDs are arranged.

Claims

1. A flexible lighting device, comprising: a housing having a longitudinal direction, the housing comprising reflective side walls extending in the longitudinal direction, a first cavity between the reflective side walls, and an opening for the passage of light from the first cavity; a plurality of separate interposers spaced apart from each other, each comprising at least one conductive connector; a plurality of light emitting diodes (LEDs), at least partially arranged, relative to each other, along the longitudinal direction of the housing, each LED having a light-emitting face and side faces and disposed on a top surface of a respective one of the plurality of separate interposers; a reflective strip completely covering a top surface of each of the plurality of separate interposers and comprising a plurality of through holes, one of the plurality of LEDs being arranged in each of the through holes, and a thickness of the reflective strip being equal to or greater than a thickness of the LEDs such that the reflective strip completely surrounds the side faces of each of the plurality of LEDs.

2. The flexible lighting device according to claim 1, wherein the reflective strip is formed integrally with the reflective side walls.

3. The flexible lighting device according to claim 1, wherein the reflective strip is configured as a cover strip with punched through holes for the LEDs.

4. The flexible lighting device according to claim 1, wherein the first cavity is at least partially filled with a transparent filler material.

5. The flexible lighting device according to claim 1, wherein a second cavity is formed between the reflective side walls and below the reflection element, wherein the interposers are arranged in the second cavity.

6. The flexible lighting device according to claim 5, wherein the housing has an H-shaped cross section.

7. The flexible lighting device according to claim 5, wherein the second cavity is at least partially filled with a reflective filler material.

8. The flexible lighting device according to claim 1, further comprising connection elements for an electrical connection between the separate interposers, wherein the connection elements are arranged in the second cavity.

9. The flexible lighting device according to claim 1, further comprising a diffusor strip arranged in the opening.

10. The flexible lighting device according to claim 1, wherein at least part of the housing comprises silicone.

11. The flexible lighting device according to claim 1 for use in automotive lighting.

12. The flexible lighting device according to claim 1, wherein at least one of the reflective side walls and the reflective strip comprises silicone with embedded reflective particles.

13. The flexible lighting device according to claim 12, wherein the silicone with the embedded reflective particles is a white silicone.

14. A method for producing a flexible lighting device, the method comprising: providing a housing having a longitudinal direction, the housing comprising reflective side walls extending in the longitudinal direction, a first cavity between the reflective side walls, and an opening of the first cavity for the passage of light from the first cavity; spacing apart a plurality of separate interposers, each of the plurality of separate interposers comprising at least one conductive connector; providing LEDs, each LED having a light-emitting face and side faces; arranging the LEDs in the first cavity with a respective one of the LEDs on a top surface of a respective one of the plurality of separate interposers such that the LEDs, relative to each other, are at least partially arranged along the longitudinal direction of the housing; and providing a reflective strip to completely cover a top surface of each of the plurality of separate interposers and comprising a plurality of through holes with one of the LEDs arranged in each of the through holes, and a thickness of the reflective strip being equal to or greater than a thickness of the LEDs, such that the reflective strip completely surrounds the side faces of each of the plurality of LEDs.

15. The method according to claim 14, wherein the housing is at least partially provided by extrusion of a profile.

16. The method according to claim 15, wherein the extrusion comprises integrally forming the reflective side walls and the reflective strip.

17. The method according to claim 14, further comprising at least one of filling the first cavity at least partially with a transparent filler material or filling a second cavity formed between the reflective side walls and the reflection element at least partially with a reflective filler material.

18. The method according to claim 14, further comprising providing a diffusor strip in the opening by molding.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples of the invention will now be described in detail with reference to the accompanying drawing, in which:

(2) FIGS. 1A and 1B show a lighting device comprising an LED in a cross-sectional view;

(3) FIG. 2 shows an embodiment of a lighting device according to the invention in a cross-sectional view;

(4) FIG. 3 shows an embodiment of a lighting device according to the invention in a cross-sectional view; and

(5) FIG. 4 shows an embodiment of a lighting device according to the invention in a schematic perspective view.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(6) In FIG. 1A, a lighting device 2 is shown in a cross-sectional view. A housing 4 comprises a cavity 6, in which an LED package 8 is arranged. The LED package 8 is disposed on an interposer 10 for electrical connection for providing electrical connection of the LED 8, wherein wires 12 are arranged in the cavity 6 to provide electrical power to the LED 8 by means of the interposer 10. The lighting device 2 further comprises a diffusor 14 arranged in an opening 16 of the cavity 6.

(7) When the lighting device 2 is operated, the effectivity can in particular be enhanced by providing a housing 4 with reflective properties, such that the LED package 8 is practically surrounded by reflective elements (i.e. the LED package 8 is put into a “white box”) except for the opening 16. However, part of the light emitted by the LED 8 and/or reflected in the cavity 6 is internally absorbed before the light can exit through the opening, e.g. by absorption on the interposer 10 or the wires 12, as light is travelling around and below the interposer 10.

(8) Therefore, as shown in FIG. 1B, part of the cavity 6 of the lighting device 2′ may be filled with a reflective material 18, which may for example embed the wires 12 and part of the interposer 10. The filling of reflective material 18 therefore improves the efficiency of the lighting device 2′. However, with the filling of reflective material 18 as shown in FIG. 1B, the interposer 10 is not completely embedded in the reflective material 18, leaving parts of the interposer 10 exposed. When using more reflective material 18 for filling, the production of the lighting device 2′ becomes difficult as it has to be avoided that reflective material 18 covers parts of the LED package 8, which would also lead to a loss in efficiency.

(9) FIG. 2 shows an embodiment of a lighting device 20 according to the invention in a cross-sectional view. The lighting device comprises a housing 22 having a longitudinal direction, which runs perpendicular to the plane of view. The housing 22 is provided by extrusion of a profile has substantially the shape of a strip with a U-shaped cross section. The housing 22 comprises reflective side walls 24 extending in the longitudinal direction, a first cavity 26 disposed between the reflective side walls 24, and an opening 28 of the first cavity 26 for the passage of light from the first cavity 26. The housing 22 and in particular the reflective side walls 24 are based on “white” silicone with embedded reflective particles such as TiOx particles. The first cavity 26 is filled with a transparent filler material and in particular with transparent silicone.

(10) LED packages 30 are provided, each LED package 30 having a light-emitting face 32 and side faces 34. The LED packages 30 are arranged on interposers 36 for providing electrical connection of the LED packages 30, wherein the LED packages 30 are mounted on a side opposite to the light-emitting face 32 to the interposers 36.

(11) The LED packages 30 are arranged together with the interposers 36 in the first cavity 26. The LED packages 30 are arranged along the longitudinal direction of the housing 22 relative to each other. A plurality of LED packages 30 is provided, wherein each LED package 30 has a separate interposer 36, such that the lighting device 20 is flexible in between the interposers 36 and LED packages 30 due to the housing 22 being based on silicone. Connection elements 38 configured as wires are provided for an electrical connection between the interposers, wherein the wires also allow a flexing of the lighting device 20 in between the interposers 36. The LED packages 30, interposers 36, and connection elements 38 are embedded in the transparent filler material of the first cavity 26. Further, the LED packages 30 are surrounded by the housing 22 and in particular the reflective side walls 26, such that a large amount of the light emitted by the LED packages 30 is effectively reflected until the light exits through the opening 28. A diffusor strip 42 is arranged in the opening 28, wherein the diffusor strip 42 provides scattering of the light passing the opening 28, such that a softer illumination is obtained. The diffusor strip 42 comprises a protrusion shaped as a section of a circle in cross section.

(12) The lighting device 20 further comprises a reflection element 40 that covers a side of the interposers 36 facing the opening 38 and that surrounds the LED packages 30 on the side faces 34. The reflection element 40 is configured as strip comprising through holes in which the LED packages 30 are arranged. Therefore, the reflection element 40 is particularly simple to produce, while the interposer 36 is effectively covered with a reflective material to avoid light loss by absorption. The reflection element 40 may be a strip with a thickness equal to or more than the thickness of the LED packages 32, such that the side faces 34 of the LED packages 30 are effectively covered and the LED packages 32 are embedded by the reflection element 40 on their side. By using the reflection element 40 configured as strip comprising through holes, an undesired covering or blocking of the light-emitting face 32 of the LED packages 30 can be avoided. Therefore, the light loss by internal absorption is reduced, increasing efficiency of the lighting device 20, while the lighting device 20 allows for a simple manufacturing process.

(13) In the embodiment shown in FIG. 2, the reflection element 40 is configured as a cover strip with punched through holes for the LED packages 30 and as a separate element from the reflective side walls 24. For the production of the lighting device 20, the housing 22 may be provided by extrusion of a profile. The LED packages 30, interposers 36, connection elements 38, and the reflection element 40 may be inserted into the first cavity 26. The first cavity 26 may be filled with the transparent filler material and the diffusor strip 42 is molded into the opening 28.

(14) FIG. 3 shows another embodiment of a lighting device 20 according to the invention in a cross-sectional view, wherein corresponding elements have the same reference numerals as in FIG. 2. In contrast to the embodiment of FIG. 2, the reflection element 40 in FIG. 3 is formed integrally with the reflecting side walls 24. In particular, the housing 22 is provided by extrusion of a profile and based in silicone with embedded reflective particles, wherein the reflective side walls 24 and the reflection element 40 are formed together with the extrusion. In the extruded profile, through holes for the reflection element 40 may be formed by punching and/or cutting. The cross section of the housing 22 is substantially H-shaped with an opening 28 of the first cavity 26 for the passage of light from the first cavity 26. A rear opening 44 of a second cavity 46 is being formed between the reflecting side walls 24 and the reflection element 40.

(15) For the production of the lighting device 20, after extrusion of the housing 22 and the introduction of the through holes in the integrated reflection element 40, the LED packages 30, interposers 36, and the connection elements 38 may be inserted into the second cavity 46 through the rear opening 44, such that the LED packages 36 are arranged in the through holes. The interposers 36 and the connection elements 38 are arranged in the second cavity 46. The first cavity 26 may be filled with a transparent filler material such as transparent silicone, with the diffusor strip 42 being molded into the opening 28. The second cavity 46 is filled with a reflective filler material, in particular silicone with embedded reflective particles, which improves the thermal conductivity from the LED packages 30.

(16) FIG. 4 shows an embodiment of a lighting device 20 according to the invention in a schematic perspective view. It can be seen that the LED packages 30 are arranged along the longitudinal direction of the housing 22. LED packages 30 and corresponding interposers 36 are spaced apart such that the lighting device 20 is configured as a flexible strip. In particular, the lighting device 20 may be used in automotive lighting such as automotive interior light, wherein the lighting device 20 can conform to various shapes due to its flexible properties.