RETROFIT LIGHTING DEVICE WITH IMPROVED THERMAL PROPERTIES

Abstract

A lighting device (1) is provided comprising a support structure (13) extending from a heat sink (10) and comprising a mounting section (14) with a central mounting face (14.2), first and second lateral mounting faces (14.1, 14.3), and at least one heat dissipation member (18a, 18b) extending from an outer face (11a.1, 11a.3) of the support structure (13) comprising a respective one of the first and the second lateral mounting faces (14.1, 14.2), the at least one first heat dissipation member (18a, 18b) comprising an inclined surface (19a, 19b) which is inclined with respect to the respective one of the first and the second lateral mounting faces (14.1, 14.3) such that a thickness of the at least one first heat dissipation member (18a, 18b) increases along a direction (40) away from the mounting section (14).

Claims

1. A lighting device comprising: a support structure extending in a first direction from a heat sink and comprising a mounting section that has a central mounting face and first and second lateral mounting faces, each of the first and second lateral mounting faces being adjacent to the central mounting face and forming an angle with the central mounting face; a first arrangement of at least two light emitting elements arranged along the first direction on the central mounting face; a second arrangement of at least two light emitting elements arranged along the first direction on the first lateral mounting face; a third arrangement of at least two light emitting elements arranged along the first direction on the second lateral mounting face; and at least one first heat dissipation member extending from an outer face of the support structure and comprising an inclined surface, the inclined surface inclined with respect to a respective one of the first and the second lateral mounting faces of the support structure such that a respective thickness of the at least one first heat dissipation member increases away from the mounting section along a second direction perpendicular to the first direction.

2. The lighting device according to claim 1, wherein a proximal edge of the at least one first heat dissipation member is arranged essentially adjacent to the second or third of at least two light emitting elements corresponding to the respective one of the first and the second lateral mounting faces.

3. The lighting device according to according to claim 2, wherein the outer face, from which the at least one first heat dissipation member extends, comprises a first surface portion and a second surface portion separated from the first surface portion by a step, the second surface portion comprises the respective one of the first and the second lateral mounting faces, and the proximal edge of the at least one first heat dissipation member is arranged on the second surface portion.

4. The lighting device according to claim 3, wherein the inclined surface extends from the proximal edge of the at least one first heat dissipation member to a distal edge of the at least one first heat dissipation member, the at least one first heat dissipation member comprises an essentially triangular cross-section with one corner of the triangular cross-section being formed by the proximal edge and with a side of the triangular cross-section opposing said one corner forming the distal edge.

5. The lighting device according to claim 1, wherein the support structure comprises at least one mounting recess and the at least one first heat dissipation member is a separate member received at least in part by the at least one mounting recess.

6. The lighting device according to claim 1, wherein the mounting section comprises respective edge portions of a first and a second layer, the first and second layers being mutually insulated and respectively configured for electrically connecting at least a respective one of the first, second, and third arrangements of at least two light emitting elements.

7. The lighting device according to claim 6, wherein the central mounting face is formed by respective faces of both edge portions of the first and the second layer, the first lateral mounting face being comprised by the first layer, and the second lateral mounting face being comprised by the second layer.

8. The lighting device according to claim 7, wherein the first and the second layers respectively comprise a printed circuit board that is an insulated metal substrate.

9. The lighting device according to claim 7, further comprising a second heat dissipation member arranged in between the first and the second layer.

10. The lighting device according to claim 9, wherein the second heat dissipation member is in direct contact with the first and the second layer.

11. The lighting device according to claim 9, wherein the second heat dissipation member partially but does not entirely overlap respective the first and the second layer along a third direction perpendicular to the first direction and the second direction.

12. The lighting device according to claim 9, wherein the second heat dissipation member comprises a layer comprising carbon fiber.

13. The lighting device according to claim 7, further comprising a third heat dissipation member arranged along an edge portion of the mounting section opposing the central mounting face.

14. The lighting device according to claim 13, wherein the third heat dissipation member comprises at least one heat pipe arranged along respective edge portions of the first and the second layer.

15. The lighting device according to claim 13, wherein the third heat dissipation member comprises at least one heat pipe with a triangular, circular, or polygonal cross-section.

16. The lighting device according to claim 13, wherein the third heat dissipation member is in direct contact with the first and the second layer.

17. The lighting device according to claim 13, wherein the third heat dissipation member does not overlap the first and the second layer along a third direction perpendicular to the first direction and the second direction.

18. The lighting device according to claim 1, wherein the first and the second lateral mounting faces are arranged to be mutually parallel and to form an angle of 90°±5° with the central mounting face.

19. A method of manufacturing the lighting device of claim 1, the method comprising: providing a support structure extending in a first direction from the heat sink and comprising a mounting section with a central mounting face and the first and second lateral mounting faces, each of the first and second lateral mounting faces being adjacent to the central mounting face and forming an angle with the central mounting face; providing a first arrangement of at least two light emitting elements arranged along the first direction on the central mounting face; providing the second arrangement of at least two light emitting elements arranged along the first direction on the first lateral mounting face; providing the third arrangement of at least two light emitting elements arranged along the mounting direction on the second lateral mounting face; and providing the at least one first heat dissipation member extending from the outer face (11a.1, of the support structure and comprising the inclined surface, the inclined surface inclined with respect to a respective one of the first and the second lateral mounting faces of the support structure such that a respective thickness of the at least one first heat dissipation member increases away from the mounting section along a second direction perpendicular to the first direction.

20. An automotive headlight comprising the lighting device according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Examples of the invention will now be described in detail with reference to the accompanying drawings, in which:

[0034] FIG. 1 illustrates a headlight with a conventional halogen lamp

[0035] FIG. 2A illustrates a lighting device according to an embodiment;

[0036] FIG. 2B exemplarily illustrates a detail of the lighting device according to FIG. 2A;

[0037] FIG. 2C illustrates the lighting device of FIG. 2A where first heat dissipation members have been removed;

[0038] FIG. 3 illustrates a part of a lighting device according to an embodiment; and

[0039] FIG. 4 illustrates a part of a lighting device according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] FIG. 1 shows a headlight 100 with a reflector 120 to which an exemplary conventional H7 halogen lamp 110 is mounted. A filament 111 of halogen lamp 110 is placed at or near focus of reflector 120 such that light 132 emitted from filament 111 is reflected by the reflector 120 along a main lighting direction 150. A cover 121 may incorporate suitable optics for shaping the reflected light and to form light 133 leaving headlight 100. Lamp 110 comprises a socket 114 mounted to reflector 120 via mounting portion 116. Pins 117a and 117b extend from socket 114 for power connection. Bulb 113 extends from base portion 115 surrounding filament 111 and ends in a light blocking portion 112 which blocks direct light from filament 111.

[0041] FIGS. 2A, 2B and 2C show respective views of an exemplary lighting device 1 according to an embodiment of the invention. Specifically, FIG. 2A shows a three-dimensional view of part of the lighting device 1 where two first heat dissipation members 18a, 18b are mounted to respective mounting recesses 11a, 11b and FIG. 2C shows a three-dimensional view of the part of the lighting device 1 of FIG. 2A where the heat dissipation members 18a, 18b are not mounted to respective mounting recesses 11a, 11b. FIG. 2B shows mounting section 14 of the lighting device 1 of FIGS. 2A and 2C in detail.

[0042] Lighting device 1 is an example of an LED (light emitting diode) retrofit to be, for example, connected to a corresponding automotive headlight (not shown). Replacing bulb 113 and filament 111 of FIG. 1, lighting device 1 comprises a support structure 13 and arrangements 20, 21 and 22 of light emitting diodes (LEDs) which are examples of light emitting elements. Support structure 13 extends from a heat sink 10, which may comprise, be connected to, and/or correspond to a socket (not shown in the figure) for mounting lighting device 1 to the headlight.

[0043] FIG. 2B illustrates support structure 13 comprising a mounting section 14 with a central mounting face 14.2 and first and second lateral mounting faces 14.1, 14.3. The first lateral mounting face 14.1 and the second lateral mounting face 14.3 are each directly adjacent to the central mounting face 14.2 and each form an angle of 90°±5° with the central mounting face 14.2. A first arrangement 21 of LEDs 21.1, 21.2, 21.3, 21.4, and 21.5 is arranged along mounting direction 30 on the central mounting face 14.2. A second arrangement 20 of LEDs 20.1, 20.2, 20.3, 20.4, and 20.5 is arranged along the mounting direction 30 on the first lateral mounting face 14.1. A third arrangement 22 of LEDs 22.1, 22.2, 22.3, 22.4, and 22.5 is arranged along the mounting direction 30 on the second lateral mounting face 14.3 (for purposes of clarity, only LED 22.5 is labelled in the FIG. 2B, but LEDs 22.1, 22.2, 22.3, and 22.4 are illustrated behind the first arrangement 21).

[0044] Turning back to FIG. 2A, two first heat dissipation members 18a, 18b are mounted to respective mounting recesses 11a, 11b (see FIG. 2C) of the support structure 13, the first heat dissipation members 18a, 18b being separate members. In an embodiment, the first heat dissipation members 18a, 18b are made of copper. Separated first heat dissipation members 18a, 18b of copper give the advantage of particularly beneficial heat transport capability usable in close proximity with the heat sources (the LEDs), while a generally cheaper material of less heat transport capability such as aluminum may be used as material of heat sink 10.

[0045] First heat dissipation members 18a, 18b respectively extend from an outer face 11a.1, 11a.2, 11a.3 (see FIG. 1C) of the support structure 13 and respectively comprise an inclined surface 19a, 19b which is inclined with respect to a respective one of the first and the second lateral mounting faces 14.1, 14.3 from which the respective first heat dissipation members 18a, 18b extend. A thickness of the at least one first heat dissipation member 18a, 18b thus increases along second direction 40 away from the mounting section 14. The second direction 40 may be perpendicular to the mounting direction. In other words, for example, inclined surface 19a extends from proximal edge 19a.1 of first heat dissipation member 18a to a distal edge 19a.2 of first heat dissipation member 18a, first heat dissipation member 18a comprising an essentially triangular cross-section (when viewed from the mounting direction) with one corner of the triangular cross-section being formed by proximal edge 19a.1 and with a side of the triangular cross-section opposing said corner forming the distal edge 19a.2. A side of the triangular cross-section of first heat dissipation member 18a in contact with support structure 13 is thus matched in shape with the first surface portion 11a.1, with step 11a.2 and with the second surface portion 11a.3. In this way, first heat dissipation member 18a is mounted precisely and reliably, allowing first heat dissipation member 18a to be arranged essentially adjacent to the second arrangement 20 of LEDs 20.1, 20.2, 20.3, 20.4, and 20.5 arranged on the first lateral mounting face 14.1.

[0046] The first heat dissipation members 18a, 18b advantageously allow for heat to be trans-ported away from the LEDs mounted to mounting section 14. For example, if the lighting device 1 is operated without the first heat dissipation members 18a, 18b (such as shown in FIG. 2C), respective temperatures of the LEDs 20.1, 20.2, 20.3, 20.4, and 20.5 of the second arrangement 20 are 99.04° C., 110.41° C., 113.49° C., 111.38° C. and 97.56° C. These temperatures are reduced to 92.96° C., 101.37° C., 103.75° C., 101.95° C. and 92.39° C. upon same operation conditions when first heat dissipation members 18a, 18b are mounted to support structure 13. In other words, a particular temperature of the central LED 20.3 which becomes hottest upon operation is reduced by about 10° C. as a result of the first heat dissipation members 18a, 18b. Thus, by only adding first heat dissipation members 18a, 18b, the function of an existing heat sink can be advantageously improved.

[0047] Turning back to FIG. 2B, mounting section 14 comprises respective edge portions of a first layer 13.1 and of a second layer 13.2, which are mutually insulated by a dielectric insulation layer 17. First and second layers 13.1 and 13.2 respectively correspond to insulated metal substrates (IMSs), respectively including further layers 13.1a, 13.1b, 13.2a and 13.2b which may serve to provide respective polarities for suitably contacting LEDs of the arrangements 20, 21 and 22 of LEDs. Thereby, the central mounting face 14.2 is formed by respective faces of both edge portions of the first and the second layers 13.1, 13.2, the first lateral mounting face 14.1 is fully comprised by the first layer 13.1, and the second lateral mounting face 14.3 is fully comprised by the second layer 13.2.

[0048] FIG. 3 depicts, in an embodiment, a cross-section of support structure 13 advantageously allowing for insertion of a second heat dissipation member 15 in the form of a thin foil of carbon fiber in between the first and second layers 13.1, 13.2 of support structure 13. The cross-section depicted in FIG. 3 is seen in a third direction that may be perpendicular to the mounting direction 30 and the direction 40. The second heat dissipation member 15 may be in direct contact with each of the first and second layers 13.1, 13.2. The second heat dissipation member 15 is shown FIG. 3 to be mounted on the second layer 13.2. In an embodiment, the second heat dissipation member 15 covers only part of the area of second layer 13.2, and part of the area of first layer 13.1 The second heat dissipation member 15 may further extend and may be mechanically connected to heat sink 10 to further support transport of heat from the LEDs to heat sink 10.

[0049] FIG. 4 depicts, in an embodiment, a cross-section of support structure 13 with a third heat dissipation member 16 in the form of a heat pipe. The heat pipe 16 is arranged along an edge portion of mounting section 14 opposing the central mounting face 14.2, i.e., along respective edge portions 13.1c, 13.2c of the first and second layers 13.1, 13.2 (first layer 13.1 and its edge portion 13.1c not shown for better visibility of remaining parts). The heat pipe 16 may be in direct contact with both of the first and second layers 13.1, 13.2 via the respective edge portions 13.1c, 13.2c. As illustrated, the heat pipe 16 may not overlap any area of the first and the second layers 13.1, 13.2 along the third direction from which FIG. 4 depicts the cross-section of support structure 13. Heat pipe 16 is in mechanical and thermal connection with heat sink 10 to further support heat transport. While heat pipe 16 may be provided with a circular cross-section, in an embodiment, at least one outer face of heat pipe 16 which is in contact with support structure 13 and/or the first and/or the second layer 13.1, 13.2 is flat. Thereby, a particularly advantageous thermal contact between heat pipe 16 and/or the support structure 13 and/or the first and/or the second layer 13.1, 13.2 is enabled. To this end, for example, in an embodiment, heat pipe 16 comprises a triangular or polygonal cross-section when viewed from the mounting direction.

TABLE-US-00001 LIST OF REFERENCE SIGNS: Lighting device 1 Heat sink 10 Mounting recesses 11a, 11b Outer face (First surface portion, Step, 11a.1, 11a.2, 11a.3 Second surface portion) Support structure 13 First layer 13.1 Second layer 13.2 Edge portions of first and second layers 13.1c, 13.2c Further layers of first and second layer 13.1a, 13.1b, 13.2a, 13.2b Mounting section 14 First lateral mounting face 14.1 Central mounting face 14.2 Second lateral mounting face 14.3 Second heat dissipation member 15 Third heat dissipation member 16 Dielectric insulation layer 17 First heat dissipation members 18a, 18b Inclined surfaces 19a, 19b Proximal edge of the first heat dissipation 19a.1 member Distal edge of the first heat dissipation 19a.2 member Second arrangement of at least two light 20 emitting elements LEDs of second arrangement 20.1, 20.2, 20.3, 20.4, 20.5 First arrangement of at least two light 21 emitting elements LEDs of first arrangement 21.1, 21.2, 21.3, 21.4, 21.5 Third arrangement of at least two light 22 emitting elements LEDs of third arrangement 22.1, 22.2, 22.3, 22.4, 22.5 Mounting direction 30 Second direction 40 Headlight 100 Halogen lamp 110 Filament 111 Light blocking portion 112 Bulb 113 Socket 114 Base portion 115 Mounting portion 116 Pins 117a, 117b Reflector 120 Cover 121 Light rays 132, 133 Main lighting direction 150