WO2009133199A2

WO2009133199A2 - A light

Info

Publication number: WO2009133199A2
Application number: PCT/EP2009/055316
Authority: WO
Inventors: Edward Henderson
Original assignee: Intram Barwell Limited
Priority date: 2008-05-02
Filing date: 2009-05-01
Publication date: 2009-11-05
Also published as: WO2009133199A3; GB0808100D0

Abstract

A light comprising a housing, a light source, a light source mounting means and a heat sink for dissipating heat generated by the light source, wherein the light is configured to transfer heat energy from the light source to the heat sink and the heat sink is disposed within the housing such that the heat sink dissipates heat energy within the housing.

Description

A Light

Description

The present invention relates to a light. In particular, the invention relates to a light having means to dissipate heat generated by a light source.

Recessed lights, or downlighters, are generally known and are used to mount a light source in a wall, ceiling or the like. Such recessed lights are usually fitted in an aperture which is pre-cut in a suitable surface and into which the light is disposed such that it is recessed therein. The light source is then capable of emitting light to illuminate a room and the rear of the light projects into a recess void behind the surface.

Conventional recessed lights commonly use a filament lamp or a compact fluorescent lamp as a light source, however in recent years there has been a desire to reduce the power consumption of such lights. One solution to this problem is to use Light Emitting Diodes (LEDs) which have a very low power consumption and a long service life. However, a problem with LEDs is that they have a very small surface area and so they require additional means of dissipating the heat generated by each LED in order to maintain the specified light output of the LEDs and ensure the rated life of such a light source.

With conventional light sources the generated heat energy is dissipated into the all- around the lamp due to the large surface area of the lamp. In particular, the heat energy is dissipated into the void into which the rear of the light projects.

A problem with dissipating heat energy directly into the void behind the mounting surface is that the void is an uncontrolled environment, and so the amount of heat energy that is dissipated varies depending on the location of the light, the size of the void and any foreign objects disposed in the void relative to the light. For example, where a light is recessed into a ceiling, the void may be filled with thermal insulation material which restricts the dissipation of heat energy from the light. The present invention seeks to provide a light that overcomes or substantially alleviates the problems with conventional lights referred to above by enabling improved dissipation of heat energy generated by the lamp or light source.

According to the present invention, there is provided a light comprising a housing, a light source, a light source mounting means and a heat sink for dissipating heat generated by the light source, wherein the light is configured to transfer heat energy from the light source to the heat sink and the heat sink is disposed within the housing such that the heat sink dissipates heat energy within the housing.

The light source mounting means may be configured to transfer heat energy from the light source to the heat sink.

Preferably, the light source mounting means comprises a printed circuit board and the light source may be mounted to the printed circuit board.

The light source may be at least one LED.

The heat sink conveniently comprises a planar surface and the light source mounting means is preferably mounted to the planar surface for aiding heat transfer from the light source to the heat sink.

The light source mounting means may be mounted to the planar surface by a bolt.

In a preferred embodiment, the heat sink further comprises a recess, the light source mounting means and light source being disposed in the recess.

The recess may have tapered sides extending outwardly from the light source mounting means to a recess opening for reflecting light emitted from the light source. In one embodiment, the heat sink comprises at least one fin extending therefrom and the light source may be mounted on one side of the heat sink and the at least one fin may extend from an opposing side.

Advantageously, the light source is disposed in the housing proximate to a housing opening and the at least one fin extends into the housing.

The heat sink may comprise a plurality of fins extending perpendicularly from a body portion of the heat sink.

Preferably, the heat sink body portion comprises a circular face, and the fins extend from the circular face and are arranged in a circumferential arrangement.

In a preferred embodiment, the heat sink comprises two rows of fins, an outer row disposed proximate to an edge of the circular face, and an inner row having a smaller circumferential arrangement disposed on the circular face, inside the outer row.

In another preferred embodiment, distal ends of the inner row of fins extend further from the circular face of the heat sink body portion than distal ends of the outer row of fins.

The light may further comprise a lens to focus light emitted by the light source and the lens may be disposed in the recess.

Advantageously, the lens is mounted on the light source mounting means.

The light may also further comprise a retaining ring, and the retaining ring, heat sink, light source and light source mounting means may form a light source assembly mounted in the housing. Pr eferably, the retaining ling is fixedly mounted to the outer surface of the heat sink and extends therearound such that an inner surface of the retaining ring communicates with the heat sink outer surface.

Advantageously, the retaining ring comprises an inner shoulder circumferentially extending from an inner surface of the retaining ring at one end thereof, the inner shoulder fixedly mounting the lens to the heat sink.

In one embodiment, the retaining ring is fixedly mounted to the heat sink by at least one screw.

The light may also include a bezel, wherein the retaining ring is fixedly mounted to the bezel.

The bezel is preferably fixedly mounted to the housing.

In an advantageous embodiment, the bezel and the retaining ring are integrally formed.

Preferably, the bezel and retaining ring are configured such that heat energy is conducted from the retaining ring to the bezel.

The light source assembly may be rotatable relative to the housing.

The bezel may further comprise a fixed ring and a tilt ting which are rotatable relative to each other about a diametrically extending axis, wherein the fixed ring is mounted to the housing and the tilt ring is mountable to the retaining ring such that the light source assembly is rotatable relative to the housing.

The heat sink and the retaining ring may be formed from aluminium. Preferably, heat transfer paste is disposed between the heat sink and each of the retaining ring and the light source mounting means.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIGURE 1 is a perspective view of a light in accordance with an embodiment of the invention;

FIGURE 2 is a partially exploded perspective view of the light shown in Figure 1;

FIGURE 3 is a partially exploded perspective view of a light assembly of the light shown in Figure 1 ; FIGURE 4 is a partially exploded side view of the light assembly shown in Figure 3 with the retaining ring excluded;

FIGURE 5 is an exploded side view of the light assembly shown in Figure 3;

FIGURE 6 is a side view of a heat sink of the light shown in Figure 1;

FIGURE 7 is a cross-sectional side view of the heat sink shown in Figure 6; FIGURE 8 is another side view of the heat sink shown in Figure 6;

FIGURE 9 is a top plan view of the heat sink shown in Figure 6;

FIGURE 10 is a bottom plan view of the heat sink shown in Figure 6;

FIGURE 11 is a side view of the retaining ring of the light shown in Figure 1;

FIGURE 12 is a cross-sectional view of the retaining ring shown in Figure 11; FIGURE 13 is another cross-sectional view of the retaining ring shown in Figure

11;

FIGURE 14 is a top plan view of the retaining ring shown in Figure 11; and

Referring now to Figures 1 to 3, there is shown in Figure 1 a light 1 according to the present invention, comprising a housing 2, an electronic light source driver 3, and a bezel 4. The housing 2 is substantially cylindrical, although it may taper from a lower end 5 proximate to the bezel 4 towards a upper end 6. Referring to Figure 2, the housing 2 further comprises a base 7 formed at the upper end 6 to enclose said uppeϊ end 6 and a flange 8 extending circumferentially around the lower end 5 of the housing 2. The flange 8 has a planar lower surface 9 and a planar upper surface 10 extending parallel to each other. The lower end 5 of the housing 2 is open to form an opening 11. The housing 2 is formed from a fire-rated and draught-proof material.

A compressing ring 12 formed from a resilient material is disposed on the flange upper surface 10 and extends therearound. The compressing ring 12 also acts as an insulating material. Retention springs 13 are also mounted to an outer surface 14 of the housing 2. The retention springs 13 and compressing ring 12 are conventional and are used to mount the light 1 in a pre-formed aperture in a wall, ceiling or the like by conventional means, and so no further explanation will be given herein.

The bezel 4 is mounted to the housing 2 by pop-riveting and is held securely against the lower surface 9 of the flange 8. The electronic light source driver 3 is securely mounted to the outer surface 14 of the housing 2 by known means proximate to the upper end 6 of the housing 2. An aperture 16 is formed through the housing 2 proximate to the upper end 6 thereof to receive a cable 17 extending from a light source assembly 18 to communicate with the electronic light source driver 3, for reasons that will become apparent hereinafter. A mains cable 24 extends from the electronic light source driver 3 to connect to a power supply (not shown) to supply electrical power to the light 1.

The light source assembly 18 is shown in Figure 3 and comprises a retaining ring 19, a heat sink 20, a light source 21, a light source mounting 22 and a lens 23. The light source assembly 18 is mounted to the bezel 4 such that it is mounted in the housing 2 when the light 1 is assembled, as will be explained hereinafter.

According to the exemplary embodiment described herein, the light source 21 is a plurality of Light Emitting Diodes (LEDs). In the exemplary embodiment (refer to Figure 3) three LEDs 21 are shown, however it will be appreciated by a person skilled in the art that the invention is not limited thereto and that any number of LEDs may be used, or a single LED may be used. The LEDs 21 are mounted to a lower face 25 of the light source mounting 22. The light source mounting 22 is a circular aluminium backed printed circuit board (P. C. B), although the invention is not limited thereto. The LEDs are mounted by known means and so no further description will be given herein. The cable 17 is electronically connected to the printed circuit board to supply power to the LEDs 21. Three mounting holes 27 are formed in the light source mounting 22 equidistant from each other for mounting the lens 23, as will be explained hereinafter and a through hole 26 is formed in the centre of the light source mounting 22 and extends therethrough between the lower face 25 and an upper face 28 of the light source mounting 22.

The lens 23 comprises a main body 29 with a cylindrical outer surface 30, as shown in Figure 4. Lens portions 31 are formed as conical frustums extending from a lens main body upper face 32, wherein the upper ends 33 of the lens portions

31correspond to the positioning of the LCDs 21 disposed on the light source mounting 22, as will become apparent hereinafter. The lens 23 is configured to focus the light emitted by each LCD 21 such that a focused beam or wide angle of light is emitted from the light 1.

Three legs 35 extend from the lens main body upper face 32 and are disposed to extend from between the lens portions 31. Each leg 35 has a stub 36 at its distal end 37 and the positioning of each stub 36 corresponds to the location of the mounting holes 27 formed in the light source mounting 22 such that each stub 36 is locatable in a respective mounting hole 27 and the lens 23 is mounted thereto when the light 1 is assembled. The lens main body 29 has a planar lower face 38 with a textured surface to diffuse the light emitted therethrough, although it will be understood that the invention is not limited thereto.

The heat sink 20 is shown in Figures 6 to 10. The heat sink comprises a cylindrical portion 40, an outer flange section 41 and an inner flange section 42. In the exemplary embodiment described herein, the heat sink 20 is formed from die-cast aluminium, although it will be understood by a person skilled in the art that the heat sink 20 may be formed from a range of materials with good thermal conductivity.

A cylindrical recess 43 is formed in a lower end 44 of the cylindrical portion 40. The cylindrical recess 43 has a base 45 and an inner surface 46 that tapers inwardly from the cylindrical portion lower end 44 to the base 45. The base 45 has a planar surface and substantially corresponds to the upper face 28 of the light source mounting 22 such that the light source mounting 22 is seated thereon when the light 1 is assembled. The cylindrical recess inner surface 46 extends circumferentially therearound and is machined smooth and polished during manufacture such that the surface is reflective to reflect light emitted by the LEDs 21.

A bolt hole 48 is formed in the cylindrical portion 40, extending from the centre of the cylindrical recess base 45 and is tapped to engagably receive a bolt 49 (refer to Figure 4), for reasons that will be explained hereinafter. A pair of tapped holes 50 are formed diametrically opposite each other in the circumferential outer surface 51 of the cylindrical portion 40. The tapped holes 50 are tapped to engagably receive bolts (not shown), as will be explained below.

The cylindrical portion 40 also has a pair of cable apertures 52 formed adjacent to each other which extend from the circumferential outer surface 51 to the recess inner surface 46 of the cylindrical portion 40.

Referring in particular to Figure 9, a plurality of outer flange portions 54 and inner flange portions 55 are formed extending from an upper end 56 of the cylindrical portion 40. The outer flange portions 54 have a circumferential outer surface 57 corresponding to the outer surface 51 of the cylindrical portion 40 and are arcuate such that they extend in a circumferential arrangement. Gaps are formed between each outer flange portion 54 which have an arced lower end 58.

The inner flange portions 55 are arcuate and the inner flange portion edges 60 are diametrically aligned with the outer flange portion edges 61 and they extend in a circumferential arrangement. Gaps are formed between each inner flange portion 55 which have an arced lower end 62. The inner flange section 42 defines a central recess 63.

Inner surfaces 64 of the outer flange portions 54 oppose outer surfaces 65 of the inner flange portions 55 such that the inner and outer flange sections define a ring- shaped recess 66 which extends to the upper end 56 of the cylindrical portion 40. The inner and outer surfaces 64,65 of the outer and inner flange portions 54,55 respectively taper away from each other towards upper ends 67,68 of the inner and outer flange portions 55,54 respectively, although they may be parallel. Similarly, the inner surfaces 70 of the inner flange portions 55 taper outwardly towards the upper ends 67 thereof. The tapered flange portions 54,55 aids heat transfer to the surrounding air. The inner flange portions 55 are longer than the outer flange portions 54 and extend further from the cylindrical portion 40. This enables the light source assembly 20 to tilt in the housing 2 when the light 1 is assembled, as will be explained in detail hereinafter.

In this exemplary embodiment the heat sink is arranged with two flange sections, the outer flange section 41 and the inner flange section 42. The outer flange section 41 has six outer flange portions 54 and the inner flange section 42 has six inner flange portions 42. However, the invention is not limited to the arrangement shown in the exemplary embodiment, and it will be understood by a person skilled in the art that the heat sink 20 may have different arrangements of flange sections, whereby there are a plurality of flange sections or a single flange section, or the number of flange portions in each flange section may vary. An advantage of the present arrangement is that manufacture of the heat sink 20 is simplified due to the arrangement of the flange sections.

Referring now to Figures 11 to 14, the retaining ring 19 comprises a collar portion 72 and inner and outer shoulders 73,74. The outer shoulder 74 extends circumferentially around a lower end 75 of the collar portion 72, extending outwardly from a collar outer face 76. The outer shoulder 74 comprises a lower face 77 which corresponds to a lower end 75 of the collar portion 72 and an upper face 79 opposing the lower face 77. The inner shoulder 73 extends circumferentially around the collar portion lower end 75, extending inwardly from a collar inner face 80. The inner shoulder 73 comprises a lower face 81 which corresponds to the collar portion lower end 78 and an upper face 82 opposing the lower face 81.

In the exemplary embodiment described herein, the retaining ring 19 is formed from die-cast aluminium, although it will be understood by a person skilled in the art that the retaining ring may be formed from a range of materials with good thermal conductivity.

A pair of spigots 85 extend from the collar outer face 76 and diametrically oppose each other. A pair of diametrically opposing tapered holes 86 are formed through a side wall 87 of the collar portion 72. Each tapered hole 86 is configured to recessingly seat a corresponding head of a fixing screw (not shown) to fixedly mount the retaining ring 19 to the heat sink 20.

The bezel 4 is shown in Figures 1 and 2 and comprises an aperture 90 formed therethrough wherein the diameter of the aperture 90 substantially corresponds to the outer diameter of the retaining ring outer shoulder 73. The bezel 4 further comprises spigot mounting portions (not shown) formed as bayonet type fixings, as will be explained hereinafter.

In an alternative embodiment the bezel 4 further comprises a tilt ring (not shown) and a fixed ring (not shown) wherein the tilt ring (not shown) is mounted in the fixed ring (not shown) and is rotatable relative to the fixed ring (not shown). The light source assembly 18 is mounted to the tilt ring (not shown) as described in the previous embodiment such that the light source assembly 18 is rotatable relative to the bezel fixed ring (not shown) and housing 2 to allow the direction of the light to be altered. The outer flange section 41 of the heat sink 20 is shorter than the inner flange section 42 of the heat sink 20, such that when the tilt ring (not shown) and hence the light source assembly 20 are rotated relative to the bezel fixed ring (not shown) and hence the housing 2, the light source assembly 18 has an increased range of movement before the heat sink 20 contacts the inner surface of the housing 2. Assembly of the recessed light source will now be described with reference to Figures 1 to 5.

Thermal transfer paste (not shown) is applied to the upper face 28 of the light source mounting 22 and the light source mounting 22 is disposed in the cylindrical recess 43 such that the light source mounting upper face 28 is located against the base 45 of the cylindrical recess 43. The bolt 49 extends through the through hole 26 and is fixedly engaged in the bolt hole 48 such that the light source mounting 22 is fixedly held against the heat sink 20. This ensures that a good thermal transfer is possible between the two components. The cable 17 with a pair of wires (not shown) extending therefrom extends from the electronic light source driver 3 which is fixedly mounted to the housing 2. Each wire extends through the cable apertures 52 and are fixedly mounted to the light source mounting 22 such that the LEDs 21 and the electronic light source driver 3 are electrically connected.

The lens 23 is disposed in the cylindrical recess 43 and each leg 35 locates on the light source mounting 22, such that each stub 36 locates in a corresponding mounting hole 27 to locate the lens 23. The retaining ring 19 is then slid over the heat sink 20 such that the collar inner face 80 locates against the heat sink outer surface 51. This ensures that there is good conductivity between the retaining ring 19 and the heat sink 20 and thermal transfer paste (not shown) is also disposed therebetween.

The inner shoulder 73 of the retaining ring 19 locates against the lower end 44 of the heat sink cylindrical portion 40 to position the two components relative to each other. Retaining screws (not shown) extend through the tapered recesses 86 formed in the collar portion 72 and extend into the tapped holes 50 such that they are fixedly mounted therein and the retaining ring 19 and heat sink portion 20 are fixedly mounted to each other. The retaining ring 19 also fixedly mounts the lens 23 in the cylindrical recess 43. The retaining ring 19 is fixedly mounted to the bezel 4 by means of each spigot 85 locating in a respective spigot mounting portion (not shown). The spigots 85 and spigot mounting portions form a bayonet type fixing, such that when the retaining ring 19 is rotated relative to the bezel 4, the upper end 77 of the retaining ring 19 is drawn towards a lower surface of the bezel 4 and fixedly held thereagainst. This ensures that there is good contact between the retaining ring 19 and the bezel 4 such that good thermal transfer is possible therebetween.

The light source assembly 18 is then inserted into the housing 2 and the bezel is pop fitted to the housing 2. The light 1 may then be electrically connected to a power supply (not shown) and fitted into a cut-out formed in the recess by conventional means.

In operation, a mains supply (not shown) supplies electrical energy to the LCDs 21. These produce light which is focused by the lens 23 to illuminate an environment as desired. Heat energy produced by each LCD 21 is conducted through the light source mounting 22 to the heat sink 20. The heat sink 20 then dissipates the heat energy into the atmospheric gas in the housing 2 by convection. Heat energy is also dissipated by heat transfer from the heat sink 20 to the retaining ring 19, and the heat energy is further conducted to the bezel 4. The bezel 4 is open to atmospheric air away from the surface in which the light 1 is recessed and so heat energy is dissipated thereto by convection.

In view of the above, an advantage of the present invention is that the heat sink 20 is contained within the controlled environment of the interior of the housing 2.

This arrangement achieves the desired thermal management through convection of heat energy in the heat sink 20 to the atmospheric gas in the housing 2, without exposure of the heat sink 20 to the uncontrolled environment within the void formed behind the aperture. Further, heat is also transferred to the bezel and dissipated therefrom. The above arrangement ensures that the LCDs are kept below the manufacturers stated maximum running temperature so as to prolong the life of each LCD and to maintain the specified light output. A further advantage of the present invention is that the ingress of water to the light source and light source mounting may be prevented.

A further advantage of the present invention is that the heat sink 20 enables the light source assembly 18 to be produced to a suitable size to be disposed in the housing 2 whilst ensuring that sufficient thermal dissipation is achieved.

Although in the above embodiments the heat sink 20 is shown to have a cylindrical body, wherein the heat sink fins are formed in a circular arrangement, it will be understood by a person skilled in the art that the invention is not limited thereto and the heat sink 20 may be formed in many shapes such that, for example, the heat sink fins are formed in a square-shaped arrangement.

Although the above embodiments use LEDs as a light source, it will be appreciated that the present invention is not limited thereto and may be used with any light source requiring heat to be dissipated.

It will be appreciated that the housing 2 defines a space within the housing 2 in which the heat sink is disposed, and that the heat sink dissipates heat energy to the space defined by the housing so as not to unduly increase the temperature of the housing.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that variations may be made to the above exemplary embodiments that lie within the scope of the invention, as defined in the following claims.

Claims

1. A light comprising a housing, a light source, a light source mounting means and a heat sink for dissipating heat generated by the light source, wherein the light is configured to transfer heat energy from the light source to the heat sink and the heat sink is disposed within the housing such that the heat sink dissipates heat energy within the housing.

2. A light according to claim 1, wherein the light source mounting means is configured to transfer heat energy from the light source to the heat sink.

3. A light according to claim 1 or claim 2, wherein the light source mounting means comprises a printed circuit board and the light source is mounted to the printed circuit board.

4. A light according to claim 3, wherein the light source is at least one LED.

5. A light according to any preceding claim, wherein the heat sink comprises a planar surface and the light source mounting means is mounted to the planar surface for aiding heat transfer from the light source to the heat sink.

6. A light according to claim 5, wherein the light source mounting means is mounted to the planar surface by a bolt.

1. A light according to any preceding claim, wherein the heat sink further comprises a recess, the light source mounting means and light source being disposed in the recess.

8. A light according to claim 7, wherein the recess has tapered sides extending outwardly from the light source mounting means to a recess opening for reflecting light emitted from the light source.

9. A light according to any preceding claim, wherein the heat sink comprises at least one fin extending therefrom.

10. A light according to any preceding claim, wherein the light source is mounted on one side of the heat sink and the at least one fin extends from an opposing side.

11. A light according to claim 10, wherein the light source is disposed in the housing proximate to a housing opening and the at least one fin extends into the housing.

12. A light according to any of claims 9 to 11, wherein the heat sink comprises a plurality of fins extending perpendicularly from a body portion of the heat sink.

13. A light according to claim 12 wherein the heat sink body portion comprises a circular face, and the fins extend from the circular face and are arranged in a circumferential arrangement.

14. A light according to claim 13, wherein the heat sink comprises two rows of fins, an outer row disposed proximate to an edge of the circular face, and an inner row having a smaller circumferential arrangement disposed on the circular face, inside the outer row.

15. A light according to claim 14, wherein distal ends of the inner row of fins extend further from the circular face of the heat sink body portion than distal ends of the outer row of fins.

16. A light according to any preceding claim, further comprising a lens to focus light emitted by the light source.

17. A light according to claim 16, together with claim 7, wherein the lens is disposed in the recess.

18. A light according to claim 17, wherein the lens is mounted on the light source mounting means.

19. A light according to any preceding claim, further comprising a retaining ring, wherein the retaining ring, heat sink, light source and light source mounting means form a light source assembly mounted in the housing.

20. A light according to claim 19, wherein the retaining ring is fixedly mounted to the outer surface of the heat sink and extends therearound such that an inner surface of the retaining ring communicates with the heat sink outer surface.

21. A light according to claim 20, wherein the retaining ring comprises an inner shoulder circumferentially extending from an inner surface of the retaining ring at one end thereof, the inner shoulder fixedly mounting the lens to the heat sink.

22. A light according to claim 19 or claim 20, wherein the retaining ring is fixedly mounted to the heat sink by at least one screw.

23. A light according to any of claims 19 to 22, further comprising a bezel, wherein the retaining ring is fixedly mounted to the bezel.

24. A light according to claim 23, wherein the bezel is fixedly mounted to the housing.

25. A light according to claim 23 or claim 24 wherein the bezel and the retaining ring are integrally formed.

26. A light according to any of claims 23 to 25, wherein the bezel and retaining ring are configured such that heat energy is conducted from the retaining ring to the bezel.

27. A light according to any of claims 19 to 26, wherein the light source assembly is rotatable relative to the housing.

28. A light according to any of claims 24 to 27, wherein the bezel further comprises a fixed ring and a tilt ring which are rotatable relative to each other about a diametrically extending axis, wherein the fixed ring is mounted to the housing and the tilt ring is mountable to the retaining ring such that the light source assembly is rotatable relative to the housing.

29. A recessed light according to any preceding claim wherein the heat sink is formed from aluminium.

30. A recessed light according to any of claims 19 to 30 wherein the retaining ring is formed from aluminium.

31. A recessed light according to any of claims 19 to 31 wherein heat transfer paste is disposed between the heat sink and each of the retaining ring and the light source mounting means.

32. A light substantially as hereinbefore described, with reference to the accompanying drawings.