Field of the Invention

The present invention relates to a light assembly, for example a light assembly having an LED light source, for retrofit installation with one or more parts of a previously installed lamp, such as a halogen downlight, and a method for retrofit installation of such a light assembly with one or more parts of a previously installed lamp.

Background to the Invention

Electric lamps are a consumable item, as they have a limited lifespan and need to be regularly replaced. The lifespan of an electric lamp is influenced by the technology used to generate the light. For example, incandescent lamps have a comparatively short lifespan. In addition to lifespan, another important characteristic of electric lamps is their energy consumption. Many attempts have been made to reduce the energy consumption of electric lighting. For example, fluorescent lamps use less energy than incandescent lamps, and in recent years compact fluorescent lamps have been a popular retrofit replacement for incandescent lamps in households and industry.

Light emitting diodes (LEDs) are a light source that typically has a very long lifetime. In addition, LEDs are more energy-efficient than conventional incandescent lamps. For these reasons, it is desirable to use LEDs where possible, and in many new commercial premises are being fitted with LED- based lighting as the default lighting technology.

In residential premises, electric lamps take a variety of shapes and sizes. Many recently constructed dwellings use halogen lamps inset into the ceiling as a primary form of illumination. These halogen downlights generate high intensity light, and do not impose upon the living space as there is no visible lamp descending from the ceiling. Unfortunately, these lamps are energy inefficient and generate large amounts of heat. Retrofitting LED based lights to replace inefficient incandescent or halogen lighting poses a number of problems. Not only should the LED lighting preferably be physically compatible with the light fittings of the previously installed lighting, it should preferably also generate light of a comparable brightness to the previously installed lighting. Where the previously installed lighting is very bright (such as is the case with halogen lighting) retrofitting LED-based lighting is difficult because LED lighting that is able to generate light of a sufficient brightness also generates a large amount of heat. Unless this heat can be dissipated quickly and efficiently, it tends to raise the temperature of the LED diodes, reducing their lifespan and altering their colour performance.

The present invention was developed with a view to addressing one or more of the aforementioned shortcomings of the prior art, or at least to provide a useful alternative. References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.

Summary of the Invention

According to one aspect of the present invention there is provided a light assembly for retrofit installation with one or more parts of a previously installed lamp, the one or more parts including a fitting for housing a previously installed light source, the light assembly comprising:

a first heatsink adapted to at least partially fit within the fitting; a second heatsink adapted to be mechanically and thermally connected to the first heatsink through a second opening in the fitting and to extend outside the fitting; and an LED light source including an array of one or more light emitting diodes, the LED light source being thermally connected to one or more of the first heatsink and second heatsink, and adapted to emit light through a first opening in the fitting. Preferably the previously installed lamp includes one of a halogen downlight; a fluorescent downlight; and a metal halide downlight. Preferably the downlight follows at least one of the MR11 , MR16, AR111 , PAR20, PAR30, PAR38 and GU10 formats. Advantageously the second heatsink is adapted to house a circuit used to power or control the LED light source.

Typically the second heatsink is adapted to be mechanically and thermally connected to the first heatsink at a second heatsink connection region of the second heatsink, the minimum width of the second heatsink connection region being less than the maximum width of the second heatsink. Typically the first heatsink is adapted to be mechanically and thermally connected to the second heatsink at a first heatsink connection region of the first heatsink, the minimum width of the first heatsink connection region being less than the maximum width of the first heatsink.

Preferably the first heatsink includes a first threaded portion and the second heatsink includes a second threaded portion, the first and second threaded portions being adapted to engage and thereby mechanically and thermally connect the first and second heatsinks. Preferably the first and second heatsink are generally circular in cross-section. Advantageously the first heatsink includes a first plurality of radial fins. Typically the second heatsink includes a second plurality of radial fins surrounding a hollow core.

Preferably a retaining member is adapted to be installed adjacent to the first opening in the fitting for retaining the first heatsink in an installed position with respect to the fitting.

In an alternative embodiment the first heatsink includes a first portion adapted to fit within the fitting and a second portion adapted to extend from the fitting through the second opening in the fitting, and the second heatsink is adapted to be mechanically and thermally connected to the second portion of the first heatsink.

According to a further aspect of the present invention there is provided a method for retrofit installation of a light assembly with one or more parts of a previously installed lamp, the light assembly including a light source having an array of one or more light emitting diodes, the one or more parts including a fitting for housing a previously installed light source, the method including the steps of: inserting a first heatsink through a first opening of the fitting; inserting a second heatsink through a second opening of the fitting; and mechanically and thermally connecting the first and second heatsinks.

Preferably the step of inserting the first heatsink through the first opening of the fitting includes the step of inserting the first heatsink through the first opening of a fitting adapted to house one of: a halogen downlight; a fluorescent downlight; and a metal halide downlight. Typically the step of inserting the first heatsink through the first opening of the fitting includes the step of inserting the first heatsink through the first opening of a fitting adapted to house a downlight which follows at least one of the MR11 , MR16, AR111 , PAR20, PAR30, PAR38 and GU10 formats.

Preferably the step of mechanically and thermally connecting the second heatsink to the first heatsink includes one or more of: the step of screwing the second heatsink on to the first heatsink; and the step of screwing the first heatsink on to the second heatsink.

Preferably the method includes the further step of retaining the first heatsink in position with respect to the fitting using a retaining member adapted to be installed adjacent to the first opening in the fitting.

In an alternative embodiment the step of inserting the first heatsink through the first opening of the fitting, is such that a first portion of the first heatsink is positioned within the fitting, and a second portion of the first heatsink extends from the fitting through a second opening in the fitting; and the step of mechanically and thermally connecting the second heatsink to the first heatsink involves mechanically and thermally connecting the second heatsink to the second portion of the first heatsink.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Likewise the word "preferably" or variations such as "preferred", will be understood to imply that a stated integer or group of integers is desirable but not essential to the working of the invention. Brief Description of the Drawings

Preferred embodiments of the light assembly and the method for retrofit installation of such a light assembly are hereinafter described, by way of example only, with reference to the accompanying drawings, wherein:

Figure 1 is a cross-section of a prior art MR16 halogen downlight installed in a ceiling;

Figure 2 is a cross-sectional exploded view of an embodiment of a light assembly according to the present invention, and a fitting for housing a previously installed light source;

Figure 3 is a front perspective exploded view of the light assembly of figure 2;

Figure 4 is a cross-section of the light assembly of figures 3 and 4 installed in a ceiling;

Figure 5 is a rear exploded perspective view of the light assembly of figures 2 to 4; Figure 6 is a side exploded view of the light assembly of figures 2 to 5; and,

Figure 7 is a cross-section of the light assembly of figure 6 through the line A-A. Detailed Description of Preferred Embodiments

Embodiments of the invention are suitable for retrofit installation of an LED- based light assembly using one or more parts of the previously installed lamp. The preferred embodiment is particularly suitable for retrofit installation of an LED light assembly with one or more parts of a previously installed downlight which may be a halogen, (cold cathode) fluorescent, or metal- halide downlight, or any other suitable downlight.

Figure 1 illustrates a typical installation of a halogen downlight 5 which follows the MR16 format. Embodiments of the present invention are suitable for use in retrofitting light assemblies with one or more parts of a previously installed downlight which may follow a variety of formats, including MR11 , MR16, AR111 , PAR20, PAR30, PAR38 and GU10. The invention is not limited in its application to previously installed lamps having a specific format.

As illustrated in figure 1 , halogen downlight 5 is installed in a ceiling panel 7, and is positioned within a fitting 20. Fitting 20 operates to house downlight 5. When halogen downlight 5 is replaced, fitting 20 stays in position in ceiling panel 7. The fitting 20 has a large mouth or first opening 40, through which the light from the downlight 5 is emitted (see figure 2).

Figure 2 illustrates an exploded cross-sectional view of a light assembly 10 for retrofit installation with one or more parts of a previously installed lamp (such as an MR16 halogen downlight), the one or more parts including fitting 20 for housing a previously installed light-source (such as halogen downlight 5 shown in figure 1.). The light assembly 10 includes a first heatsink 50 and a second heatsink 60. The light assembly 10 is also illustrated in figures 3 to 7. As shown in the exploded view of the assembly 10 in figure 3, light assembly 10 includes an LED light source 30 including an array of one or more light emitting diodes, adapted to emit light through the first opening 40 in fitting 20. LED light source 30 is mounted on second heatsink 60 using a thermally conductive adhesive. Accordingly, second heatsink 60 is thermally connected to LED light source 30, facilitating dissipation of heat generated by LED light source 30. In an alternative embodiment, not illustrated, LED light source 30 may be thermally connected to first heatsink 50 which, as described in more detail below, may be thermally and mechanically connected to second heatsink 60.

Figure 4 shows light assembly 10 installed in ceiling 7. First heatsink 50 is adapted to fit within fitting 20. However, in an alternative embodiment (not illustrated) first heatsink 50 may include a first portion adapted to fit within fitting 20, and a second portion adapted to extend from fitting 20 through a second opening 70 in fitting 20. In the illustrated embodiment, it is the second heatsink 60 that is adapted to extend outside fitting 20 through second opening 70.

Second heatsink 60 is adapted to mechanically and thermally connect to first heatsink 50 by means of a threaded screw arrangement. First heatsink 50 includes a first threaded portion 50t (illustrated in the exploded view of figure 5 and the cross-sectional view of figure 7) and second heatsink 60 includes a second threaded portion 60t (shown most clearly in figures 3, 6 and 7). The first threaded portion 50t and second threaded portion 60t are adapted to engage when first heatsink 50 and second heatsink 60 are rotated with respect to each other, so that first heatsink 50 and second heatsink 60 screw together. The close resulting physical contact between first heatsink 50 and second heatsink 60 ensures that first heatsink 50 and second heatsink 60 are both physically and thermally connected.

As described above, LED light source 30 is physically mounted on, and thermally connected to, second heatsink 60, and, when installed, is adapted to emit light through first opening 40 in fitting 20 of the previously installed lamp. LED light source 30 is driven using rectification and current driving circuits 80 which ensure that electricity having the right polarity, current and voltage is passed through the light emitting diode array of LED light source 30. As illustrated in figure 7, second heatsink 60 is adapted to house the rectification and current driving circuits 80 which are used to power and/or control the LED light source 30. Circuits 80 are positioned within a hollow core 60h of second heatsink 60. In the illustrated embodiment, both first heatsink 50 and second heatsink 60 are generally circular in cross-section. First heatsink 50 includes a first plurality of radial fins 50f, and second heatsink 60 includes a second plurality of radial fins 60f. The use of radial fins 50f, 60f increases the surface area of heatsinks 50, 60, thereby increasing the potential rate of heat dissipation. Heat generated by LED light source 30 flows through fins 60f of second heatsink 60, and also flows through fins 50f of first heatsink 50 due to the thermal connection between first heatsink 50 and second heatsink 60 created by second heatsink 60 being screwed into first heatsink 50. As described above, radial fins 60f of second heatsink 60 surround a hollow core 60h in which driver circuits 80 are positioned.

To facilitate installation of light assembly 10 with fitting 20, both first heatsink 50 and second heatsink 60 are preferably waisted. As illustrated in figure 6 and 7, second heatsink 60 includes a second heatsink connection region 60c at which it mechanically and thermally connects to first heatsink 50. Similarly, first heatsink 50 includes a first heatsink collection region 50c at which it mechanically and thermally connects to second heatsink 60. Second heatsink connection region 60c is tapered, such that the minimum width of this region is less than the maximum width of second heatsink 60. Similarly, first heatsink connection region 50c is also tapered, so that the minimum width of first heatsink connection region 50c is less than the maximum width of first heatsink 50.

The reduction in width of first heatsink 50 and second heatsink 60 at their respective connection regions 50c and 60c facilitates installation of light assembly 10 with fittings 20 which have a narrow second opening 70, as shown in figure 4. If the maximum width of first heatsink 50 and second heatsink 60 were constrained by the width of second opening 70 in fitting 20, the surface area of the heatsinks 50, 60 would be reduced, thereby reducing the rate of thermal dissipation. Accordingly, to maintain a high rate of thermal dissipation, first heatsink 50 and second heatsink 60 are only tapered at their respective connection regions 50c and 60c. θ

Although the illustrated embodiment shows both first heatsink 50 and second heatsink 60 as having tapered connection regions 50c and 60c respectively, in alternative embodiments only one of first heatsink 50 and second heatsink 60 may have a tapered connection region. In this regard, the specific shape of first heatsink 50 may be dictated or influenced by the shape of fitting 20.

First heatsink 50 may be retained in place with respect to fitting 20 (and ceiling 7) by means of a retaining member 90 (illustrated in figure 2) adapted to be installed adjacent first opening 40 of fitting 20. Retaining member 90 is preferably in the form of a ring which engages with fitting 20 and has a supporting member for supporting first heatsink 50 within fitting 20. Tapered connection regions 50c and 60c may also operate to restrict vertical movement of first heatsink 50 relative to fitting 20 by frictionally engaging with the edges of second opening 70 in fitting 20.

In addition to radial fins 50f, first heatsink 50 may also include a reflector 50r (see figures 2, 4 and 5) and/or a lens 501 (illustrated in figure 3) for controlling the shape of the light emitted by LED light source 30.

Light assembly 10 is retrofit with one or more parts of a previously installed lamp, the one or more parts including a fitting for housing a previously installed light source (such as fitting 20) by inserting first heatsink 50 through first opening 40 of fitting 20, inserting second heatsink 60 through second opening 70 of fitting 20, and mechanically and thermally connecting first heatsink 50 and second heatsink 60. In an alternative embodiment (not illustrated), first heatsink 50 has a first and second portion. First heatsink 50 is inserted through first opening 40 of fitting 20 such that the first portion of first heatsink 50 is positioned within fitting 20, and the second portion of heatsink 50 extends from fitting 20 through second opening 70. Second heatsink 60 can then be mechanically and thermally connected to first heatsink 50 without it being inserted through opening 70. As described above, fitting 20 may be adapted to house a downlight, including a halogen downlight which follows at least one of the MR11 , MR16, AR111 , PAR20, PAR30, PAR38 and GU10 formats. First heatsink 50 and second heatsink 60 may be mechanically and thermally connected by screwing them together. Second heatsink 60 may be screwed on to first heatsink 50 (which remains stationary), first heatsink 50 may be screwed onto second heatsink 60 (with a second heatsink 60 remaining stationary), or both heatsinks may be rotated simultaneously.

Now that a preferred embodiment of the light assembly and method for retrofit installation of such a light assembly have been described in detail, it will be apparent that the described embodiments provide a number of advantages over the prior art, including the following: (i) They facilitate the retrofit installation of a low-power LED light assembly with one or more parts of a previously installed lamp such as a halogen downlight; a fluorescent downlight; and a metal halide downlight.

(ii) Not only are they physically compatible with light fittings of previously installed lighting, they can also generate light of a comparable brightness to the previously installed lighting.

(iii) Potential problems with heat dissipation are obviated by the provision of suitable heatsinks, without compromising the physical constraints of the light fittings of previously installed lamps. It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention. For example, first heatsink 50 and second heatsink 60 may have a substantially square cross- section and/or first heatsink 50 may have different cross-sectional shape to second heatsink 60. Therefore, it will be appreciated that the scope of the invention is not limited to the specific embodiments described and is to be determined from the appended claims.