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Patent Searching and Data


Title:
A LIGHT FITTING
Document Type and Number:
WIPO Patent Application WO/2016/180687
Kind Code:
A1
Abstract:
A light fitting (10) for recessed mounting of a luminaire (200) in a substrate, comprising a base (20) having a longitudinal axis (X-X); a luminaire (200); and an adjustable coupling mechanism to adjust the position of the luminaire (200) in relation to the base (20) along both directions of the longitudinal axis (X-X). The adjustable coupling mechanism is operable by way of rotation of the luminaire (200) to couple or decouple the luminaire (200) from the base (20). The coupling mechanism comprises a pin arrangement (50a, 50b) on the base (20) and a channel arrangement (60a, 60b) on the heat sink (204) of the luminaire (200). The pin arrangement (50a, 50b) is engageable with the channel arrangement (60a, 60b) to couple the luminaire (200) in at least two different positions and is disengageable from the channel arrangement (60a, 60b) to decouple the luminaire (200) from the base (20).

Inventors:
CADISCH SIMON (GB)
BELLANO RICCARDO (GB)
Application Number:
EP2016/059928
Publication Date:
November 17, 2016
Filing Date:
May 03, 2016
Export Citation:
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Assignee:
ECOLED LTD (GB)
International Classes:
F21S8/02; F21V21/04; F21V21/14; F21V14/02; F21V29/77; F21V29/81; F21Y115/10
Foreign References:
GB2517222A2015-02-18
DE29715212U11997-11-06
Attorney, Agent or Firm:
ELLIS, Michael (East Linton, East Lothian EH40 3DU, GB)
Download PDF:
Claims:
CLAIMS:

1. A light fitting for recessed mounting of a luminaire in a substrate, the light fitting comprising:

a base having a longitudinal axis;

a luminaire; and

an adjustable coupling mechanism operable by way of rotation to adjust the position of the luminaire in relation to the base along both directions of the longitudinal axis of the base, wherein the adjustable coupling mechanism is operable by way of rotation of the luminaire to couple or decouple the luminaire from the base and wherein the coupling mechanism comprises:

a pin arrangement on one of the base or the luminaire; and

a channel arrangement on the other of the base or the luminaire, wherein the pin arrangement is engageable with the channel arrangement to couple the luminaire in at least two different positions in relation to the longitudinal axis of the base and wherein the pin arrangement is disengageable from the channel engagement arrangement to decouple the luminaire from the base. 2. A light fitting as claimed in claim 1, wherein the position of the luminaire in relation to the longitudinal axis of the base is adjustable in increments.

3. A light fitting as claimed in either one of the previous claims, wherein the base comprises a collar configured for recessed mounting in a substrate.

4. A light fitting as claimed in claim 3, wherein the collar comprises a hollow cylinder and the luminaire is configured to telescope within the collar.

5. A light fitting as claimed in any one of the previous claims, wherein the base has an outer end and an inner end at an opposite longitudinal end of the base to the outer end and wherein luminaire is adjustable between an extended position substantially at the outer end and a retracted position distal from the outer end.

6. A light fitting as claimed in claim 5, wherein the outer end of the base comprises an outer flange configured for engagement with a substrate. 7. A light fitting as claimed in any one of the previous claims, wherein the channel arrangement comprises at least one channel having a plurality of recesses and wherein each recess is offset from the next consecutive recess of the same channel in the direction of the longitudinal axis of the base. 8. A light fitting as claimed in claim 7, wherein each recess is offset from the next consecutive recess of the same channel in a direction of rotation about the longitudinal axis of the base.

9. A light fitting as claimed in either one of claims 7 or 9, wherein the channel arrangement comprises a plurality of channels.

10. A light fitting as claimed in claim 9, wherein the channels are arranged at equiangular intervals about the longitudinal axis of the base. 11. A light fitting as claimed in any one of claims 7 to 10, wherein the pin arrangement comprises a pin for the or each channel.

12. A light fitting as claimed in claim 11 , wherein the or each channel comprises a detent adjacent each recess for retaining the pin against rotation in relation to the channel.

13. A light fitting as claimed in any one of claims 7 to 12, wherein the or each channel comprises a respective stop at one end. 14. A light fitting as claimed in any one of the previous claims, wherein the coupling mechanism is operable by rotation of the luminaire in relation to the base about a substantially helical path.

15. A light fitting as claimed in any one of the previous claims, wherein the luminaire comprises a heat sink and wherein the heat sink comprises one of the pin arrangement or the channel arrangement.

16. A light fitting as claimed in claim 15, wherein the channel arrangement is formed in the heat sink and the base comprises the pin arrangement.

17. A light fitting as claimed in either one of claims 15 or 16, wherein the heat sink is releasably connected to the luminaire.

18. A light fitting as claimed in either one of claims 15 or 16, wherein the heat sink is integral with the luminaire. 19. A light fitting as claimed in any one of the previous claims, wherein the adjustable coupling mechanism is operable by way of manual grip of the luminaire optionally facilitated by finger grip on the luminaire or by way of manipulation with a special tool optionally including magnetic connection to the luminaire.

20. A base having a longitudinal axis, wherein the base is configured to be coupled to the luminaire of the light fitting of any one of the previous claims.

21. A luminaire configured to be coupled to the base having a longitudinal axis of the light fitting of any one of claims 1 to 19.

22. A heat sink configured to be coupled to the luminaire of claim 21 when appended to any one of claims 15 to 17 and 19.

Description:
A Light Fitting

The present invention relates to a light fitting for recessed mounting of a luminaire in a substrate.

Lights recessed within walls or ceilings have been popular for some time. The display industry, in particular in department stores, has used recessed light fittings for some time. A single light fitting may be used to light a general overall area or it may be used to direct light at a particular object.

Patent publication US3,660,651 discloses a light fitting for recessed mounting of a luminaire comprising a filament lamp in ceiling tiles, like the recessed light fittings found in a department store or other commercial

environments. The luminaire may be pivoted to direct light at various angles and it may be moved in a vertical direction between a position recessed in the light fitting and a position extending from the light fitting. This enables adjustment between lighting a general area, or a particular object, at various angles or light intensities.

Recessed light fittings have become popular in other situations, like, for example, the domestic environment. This popularity has gathered pace with advances in technology that have resulted in light-emitting diodes becoming a viable alternative light source to filament lamps. For the sake of brevity, the conventional term "LED" shall be used to describe a light-emitting diode hereon. The popularity of recessed light fittings is complemented by a need for economic installment techniques. Whilst the recessed light fitting of US3, 660,651 may have an adjustable light output, it comes as an assembled unit of multiple parts including the luminaire which are enclosed within a housing. The installer must mount the whole light fitting in a recess at the same time. This makes heavy work for the installer. The same applies to removal of the light fitting for maintenance, or repair, which must be done on the whole unit. The installment of the light fitting of US3, 660,651 is an inflexible process which takes time and effort.

It is an object of the present invention to provide an improved light fitting. Accordingly, in a first aspect of the present invention, there is provided a light fitting for recessed mounting of a luminaire in a substrate, the light fitting comprising: a base having a longitudinal axis; a luminaire; and an adjustable coupling mechanism operable by way of rotation to adjust the position of the luminaire in relation to the base along both directions of the longitudinal axis of the base, wherein the adjustable coupling mechanism is operable by way of rotation of the luminaire to couple or decouple the luminaire from the base and wherein the coupling mechanism comprises: a pin arrangement on one of the base or the luminaire; and a channel arrangement on the other of the base or the luminaire, wherein the pin arrangement is engageable with the channel arrangement to couple the luminaire in at least two different positions in relation to the longitudinal axis of the base and wherein the pin arrangement is disengageable from the channel engagement arrangement to decouple the luminaire from the base.

The light fitting of the present invention has an adjustable coupling mechanism that may extend, or retract, the luminaire in relation to the substrate in which the light fitting is mounted. Manipulation of the luminaire can also be used to couple, or decouple, the luminaire from the base. This enables the base to be connected to the substrate, like, for example, a wall or ceiling, without the luminaire. This reduces the weight of the installation task because only the base may be installed initially. The luminaire may be coupled, possibly tool- free, to the base later. For example, a batch of bases may be installed and then the luminaire are coupled to the bases later when the electrical power supplies are ready for connection. Alternatively, a luminaire, may be decoupled and repaired or replaced while the base remains undisturbed. The installer can manipulate the electrical power supply and connect it to a freestanding luminaire before the latter is re- coupled to the base. LED luminaires may be retro-fitted in place of filament lamps, again without disturbing the base. These are some examples of how the present invention provides a more flexible and cost effective light fitting. The coupling mechanism is operable by way of rotation of the luminaire to adjust the position of the luminaire in relation to the base along both directions of the longitudinal axis of the base. This is a simple and intuitive means of operation. Advantageously, operation of the coupling mechanism is aided by the channel arrangement which guides smooth sliding motion of the pin arrangement in a controlled manner.

Preferably, the position of the luminaire in relation to the longitudinal axis of the base is adjustable in increments. Adjustment movement may follow, for example, a straight line, a helical path, or a zig-zag path.

Adjustment in increments provides the installer with tactile feedback which is helpful if visibility is impaired.

The base may comprise a collar configured for recessed mounting in a substrate. The collar may provide a protective wall between the substrate and components of the light fitting.

Preferably, the collar comprises a hollow cylinder and the luminaire is configured to telescope within the collar. This may provide reliable guided linear movement between collar and luminaire.

Preferably, the base has an outer end and an inner end at an opposite longitudinal end of the base to the outer end and wherein luminaire is adjustable between an extended position substantially at the outer end and a retracted position distal from the outer end. The extended position may provide full light output from a luminaire in the light fitting. The retracted position may be desirable to reduce glare from the luminaire in certain locations, like, for example, near a curtain or a picture in a domestic environment. The ability to conceal the light source to a varying degree is an attractive option. The installer need install only one type of light fitting in different locations about an office, or a home, and yet still be able to adjust light intensity according to individual tastes. The customer may adjust light intensity without need to rely on the original installer.

Preferably, the outer end of the base comprises an outer flange configured for engagement with a substrate. This helps to prevent the base receding too far within a hole in a substrate. The outer flange may have an array of perforations. The outer flange may be plastered over to help conceal all but light from the light fitting. The perforations help adhesion of the plaster to the outer flange and help key the base into the substrate.

The channel arrangement may comprise at least one channel having a plurality of recesses and wherein each recess is offset from the next consecutive recess of the same channel in the direction of the longitudinal axis of the base. Each recess represents a different position of the luminaire in relation to the longitudinal axis of the base. Preferably, each recess is offset from the next consecutive recess of the same channel in a direction of rotation about the longitudinal axis of the base. This enables, for example, helical movement (which is preferred) or zig-zag movement, of the luminaire as it moves between different positions in relation to the base.

The channel arrangement may comprise a plurality of channels. Preferably, the channels are arranged at equiangular intervals about the longitudinal axis of the base. Preferably, the pin arrangement comprises a pin for the or each channel. These aspects of the invention, alone or in combination, contribute to spreading engagement between the pins and their respective channels evenly about the longitudinal axis and helping enhance smooth operation of the coupling mechanism.

Preferably, the or each channel comprises a detent adjacent each recess for retaining the pin against rotation in relation to the channel. The recess is somewhere to reliably park, or hold, the pin and the detent provides tactile feedback to someone operating the coupling mechanism that a stable resting position has been reached. Preferably, the or each channel comprises a respective stop at one end. This provides additional feedback that the most retracted position of the luminaire has been reached.

Preferably, the coupling mechanism is operable by rotation of the luminaire in relation to the base about a substantially helical path. Operation along a helical path does not require much torque and so the luminaire may be turned with fingertips, for example. If the helical path is less than one revolution then it may allow adjustment of the position of the luminaire without significantly twisting electrical power supply cables connected to a luminaire.

Preferably, the channel arrangement is formed in the heat sink and the base comprises the pin arrangement. A heat sink is useful for increasing dissipation of heat generated by the luminaire. By using the heat sink as part of the coupling mechanism, the heat sink serves an additional purpose which economises on the number of light fitting parts. Forming of the channel arrangement in the heat sink may contribute to ventilation and increase heat dissipation. The channel arrangement may be formed by moulding, laser cutting or machining into the outer periphery of the heat sink facing the pin arrangement on the base. This saves weight and may simplify the construction of the luminaire and its heat sink.

The heat sink may be releasably connected to the luminaire. This facilitates replacement and repair of the luminaire and retro-fitting of a different type of luminaire. Alternatively, the heat sink may integral with the luminaire. This reduces components and may reduce manufacturing costs which could be passed on to the customer.

Preferably, the adjustable coupling mechanism is operable by way of manual grip of the luminaire optionally facilitated by finger grip on the luminaire or operable by way of manipulation with a special tool optionally including magnetic connection to the luminaire.

In a second aspect of the present invention, there is provided a base having a longitudinal axis, wherein the base is configured to be coupled to the luminaire of the light fitting of the first aspect of the present invention. The base may be sold separately to enable to replacement or repair the original base and to avoid discarding the other components of the light fitting unnecessarily.

In a third aspect of the present invention, there is provided a luminaire configured to be coupled to the base having a longitudinal axis of the light fitting of the first aspect of the present invention. The luminaire may be sold separately to enable to replacement or repair the original luminaire and to avoid discarding the other components of the light fitting unnecessarily.

In a fourth aspect of the present invention, there is provided a heat sink configured to be coupled to the luminaire of the third aspect of the present invention. The heat sink, like the luminaire, may be sold separately to enable to replacement or repair the original heat sink and to avoid discarding the other components of the light fitting unnecessarily.

These and other features and advantages of the present invention will be better understood from the following detailed description, which is given by way of example and with reference to the accompanying drawings, in which: Figure 1 shows a perspective view from below of a light fitting for mounting in a recess in a substrate in an extended position;

Figure 2 shows a perspective view from below of a luminaire and a base of the light fitting of Figure 1 prior to assembly;

Figure 3 shows a perspective view from below of the light fitting of Figure 1 in a retracted position;

Figure 4 shows a cross-sectional view of a light fitting of Figure 1 in the extended position;

Figure 5 shows a perspective view from above the luminaire of the light fitting of Figure 1; and

Figure 6 shows a schematic diagram of a channel in the luminaire rotating in relation to a pin of the base; and

Figure 7 shows a perspective view of an alternative embodiment of a heat sink for the luminaire.

Referring to figures 1 to 6, there is shown a light fitting 10 for recessed mounting of a luminaire 200 in a substrate. The substrate may be, for example, a plasterboard wall or ceiling, or ceiling tile, that is a facade to a cavity large enough to accommodate the light fitting 10, the luminaire 200 and its associated electrical power supply cables. Alternatively, the substrate may be, for example, a solid wall formed with a recess to accommodate the light fitting 10 and the luminaire 200 and provide a conduit for its electrical power supply cables. The light fitting typically mounts a luminaire having an external diameter of about 55mm to 75mm but its simple design makes it suitable for mounting a luminaire having a much smaller, or bigger, external diameter.

The light fitting 10 comprises a trimless collar in the form of a base 20 for connection to the substrate and the luminaire 200 supported in the base by a luminaire support 32, 204. The luminaire support 32, 204 is adjustably coupled to the base 20 by an adjustable coupling mechanism 50a,50b,60a,60b as is described in more detail below. The adjustable coupling mechanism may couple and decouple the luminaire support 32, 204 from the base 20 by manipulation of the luminaire support 32, 204 as is also described in more detail below. The base 20 comprises a hollow cylindrical collar 22 having a central longitudinal axis X-X and a wide annular outer flange 24 arranged about an outer end 22a of the base collar 22 in a plane orthogonal to the longitudinal axis X-X and opposite to an inner end 22b of the base collar 22. The base collar 22 and the outer flange 24 are made as one integral part, although, optionally, they may be made of separate parts and assembled together to form the base 20. The base 20 may be made of any suitable material, provided it is fire retardant, like for example, metal, ceramic, plastic, fibre glass or composite material. The base collar 22 has an inner cylindrical surface 23.

The outer flange 24 has an array of perforations 28 of various shapes and sizes. When the light fitting 10 is mounted in a recess of a substrate, the outer flange 24 is relatively thin and it may be plastered over to conceal the base 20 within the substrate. The perforations 28 help to key the outer flange 24 into the layer of plaster to improve connection of the light fitting 10 to a substrate.

The inner cylindrical surface 23 of the base collar 22 comprises a pair of cylindrical pins 50a,50b arranged diametrically opposite each other near to the inner end 22b of the base collar 22b. The cylindrical pins 50a, 50b protrude radially inwardly a small distance (about 4mm) from the inner cylindrical face 23.

The luminaire support comprises a hollow cylindrical support collar 32 having the central longitudinal axis X-X, an annular external channel 34 and an annular internal groove 35 each arranged at an outer end 32a of the collar 32. The external channel 34 supports an external o-ring 34a. The outer end 32a of the collar 32 has an outer annual trim 36. An inner end 32b of the collar 32 opposite to the outer end 32a has an inner annular trim 38. Located between the inner annular trim 38 and the annular external channel 34 is a cylindrical recess 39 around the outside of the collar 32 where an intumescent seal IS is located. In the case of fire, the intumescent seal IS expands to fill air gaps to that the spread of fire is retarded by the light fitting 10. Intumescent seals are common in the field of lighting and are not discussed in any more detail.

The external o-ring 34a excludes draft between the base collar 22 and the support collar 32 whilst at the same time permitting relative movement between the base 20 and the luminaire 200 about or along the longitudinal axis X- X. The o-ring 34a may also provide and acoustic barrier and a moisture barrier. The collar 32 resists lateral movement of the luminaire 200 with respect to the base 20 in a plane orthogonal to longitudinal axis X-X. The support collar 32 may be made of any suitable material, provided it is fire retardant, like for example, metal, ceramic, plastic, fibre glass or composite material.

The luminaire 200 has a body 202a and optical elements like, for example, a light source 102b, a generally conical reflector 202c and a lens 202d at the outer end of the reflector 202c to direct and shape light from the light source. The lens 202d may be clear glass or plastic or it may be substituted by a frosted diffuser or a prismatic lens, as is common in the field of lighting and is not discussed in any more detail. The luminaire has control electronics (not shown) and an annular web 206 around the greatest diameter of the reflector. The luminaire 200 is surrounded by a heat sink 204 connected to the body 202a. The heat sink 204 is thermally coupled to the optical elements 202b-202d to help dissipate heat energy from the light source 202b and maintain the luminaire 200 at or below maximum operational temperature. The light source may be filament lamp or an LED, for example. The light source 202b receives electrical current from an electrical power supply cable. LEDs have a lower energy consumption, longer lifespan and greater reliability than filament lamps which make LEDs a preferred option of light source.

The heat sink 204 comprises an array of closely packed blades 204a fanning outwardly from the longitudinal axis X-X, the body 202a and the reflector 202c in a radial direction with respect to the longitudinal axis X-X from. The heat sink blades 204a are generally parallel to the longitudinal axis X-X. The outer edges of the heat sink blades 204a are parallel to the longitudinal axis X-X and define a generally cylindrical shape having the same outer diameter as the outer 36 and inner 38 annular trims of the support collar 32. The heat sink 204 and the heat sink blades 204a may be made of any suitable metal, ceramic, plastic, fibre glass or composite material provided it is fire retardant and it has good heat conduction properties.

During assembly, the luminaire 200 is inserted in the inner end 32b of the support collar 32 until the annular web 206 of the luminaire 200 into the internal annular groove 35 to secure it against the outer annular trim 36 at the outer end 32a of the collar 32. The heat sink 204 is adjacent the collar 32. The luminaire 200 may be removed from the support collar 32, but this requires reversal of the snap-fit engagement between the annular web 206 and the internal groove 35. The luminaire 200 may be connected to the support collar 32 by by any other mechanical means such as grub screws or by adhesive.

The luminaire support further comprises the heat sink 204. The heat sink 204 has a pair of generally staircase-shaped channels 60a,60b formed by, for example, molding, laser cutting or machining, in the outer edges of the heat sink blades 204a facing the inner cylindrical surface 23 of the base collar 22. The channels 60a,60b are on diametrically opposite sides of the heat sink 204 from each other. One pin 50a engages one channel 60a and the other pin 50b engages the other channel 60b. For brevity, only one channel 60a and pin 50a is described from here, however this part of the description applies equally to the other channel 60b and pin 50b.

The channel 60a comprises a mouth 62a at an inner end of the heat sink 204 opposite to an outer end of the heat sink 204 adjacent the support collar 32. From the mouth 62a, the channel 60a leads in an axial direction (direction of arrow B) to a first U-bend 64a which leads to a first recess 66a. The first recess 66a is offset by a small angle of about five to ten degrees in a clockwise direction R (about the longitudinal axis X-X and viewed from the inner end of the heat sink 204) from the mouth 62a. The first recess 66a is slightly closer to the inner end of the heat sink 204 than the trough of the first U-bend.

From the first recess 66a, the channel 60a drops 72a in an axial direction (direction of arrow B) to a second U-bend 74a which leads to a second recess 76a. The second recess 76a is offset by a small angle of about five to ten degrees in a clockwise direction R about the longitudinal axis X-X from the first recess 66a. The second recess 76a is slightly closer to the inner end of the heat sink 204 than the trough of the second U-bend 74a. The second recess 76a is closer to the outer end of the heat sink 204 than the first recess 66a.

From the second recess 76a, the channel 60a drops 82a in an axial direction (direction of arrow B) to a third U-bend 84a which leads to a third recess 86a. The third recess 86a is offset by a small angle of about five to ten degrees in a clockwise direction R about the longitudinal axis X-X from the second recess 76a. The third recess 86a is slightly closer to the inner end of the heat sink 204 than the trough of the third U-bend 84a. The third recess 86a is closer to the outer end of the heat sink 204 than the second recess 76a.

From the third recess 86a, the channel 60a drops 82a in an axial direction (direction of arrow B) to a fourth U-bend 94a which leads to a fourth recess 96a. The fourth recess 96a is offset by a small angle of about five to ten degrees in a clockwise direction R about the longitudinal axis X-X from the third recess 86a. The fourth recess 96a is slightly closer to the inner end of the heat sink 204 than the trough of the fourth U-bend 94a. The fourth recess 96a is closer to the outer end of the heat sink 204 than the third recess 86a.

From the fourth recess 96a, the channel 60a drops 92a in an axial direction to a fifth and final U-bend 104a which leads to a fifth and final recess 106a which is the end of the channel 60a. The fifth recess 106a is offset by a small angle of about five to ten degrees in a clockwise direction R about the longitudinal axis X-X from the fourth recess 96a. The fifth recess 106a is slightly closer to the inner end of the heat sink 204 than the trough of the fifth U-bend 104a. The fifth recess 106a is the closest of all the recesses to the outer end of the heat sink 104.

The recesses 66a, 76a, 86a, 96a, 106a are arranged along a substantially helical path HP about the heat sink 104 beginning at the first recess 66a and following consecutively, in the direction of clockwise rotation R, with the second recess 76a, the third recess 86a, the fourth recess 96a and the fifth recess 106a. The helical path HP typically has a helix angle γ of between about 40 and 50 degrees, but this simple design of light fitting may facilitate smaller, or greater, helix angles.

The light fitting 10 comprises an adjustable coupling mechanism configured to couple, decouple and adjust the luminaire support 32, 204 in relation to the base 20. The coupling mechanism comprises the pair of pins 50a, 50b and the pair of channels 60a, 60b. The coupling mechanism is operable by way of manipulation of the luminaire support 32, 204 as is explained in detail below. This manipulation may be by factional contact between an installer's fingers and the support collar 32 which could be supplemented by, for example, finger grips. Alternatively, some form of connection, like, for example, magnets inside the collar 32 may be used to temporarily connect with a special tool to facilitate manipulation of the collar 32.

The inner diameter of the base collar 22 is slightly greater than the diameter of the circumference circumscribed by the support collar 32 and the heat sink blades 204a. This permits rotation, in clockwise R and anti-clockwise R' directions, and axial movement, in the up direction A and the down direction B, of the luminaire support 32, 204 in relation to the base 20 and its longitudinal axis X- X.

Assembly of the light fitting 10 shall now be described. The base 20 is seated in a circular hole in a substrate with the base outer flange 24 flush against the substrate to which the base 20 is firmly connected. Preferably, the base outer flange 24 is plastered over to increase adhesion between the base 20 and the substrate and to improve aesthetics by concealing all but the luminaire 200 and its light. The outer end 22a may have a small circumferential rim to act as a barrier to the layer of plaster. An electrical power supply cable is pulled from the cavity and through the base collar 22 for connection to a luminaire 200. The luminaire 200 is connected to the luminaire support 32, 104 as described above. The luminaire support 32, 204 is ready to be coupled, via the adjustable coupling mechanism 50a,50b,60a,60b, to the base 20 to unite the light fitting 10 and suspend the luminaire 200 from the substrate.

The installer holds the luminaire 200 by the support collar 32. The installer inserts the heat sink 204 and then the collar 32 into the outer end 22a of the base collar 22 and slides them up in the direction of arrow A towards the inner end 22b of the base collar 22. Movement of the luminaire support 32, 204 in the direction of longitudinal axis X-X is guided by the heat sink blades 204a and the inner annular trim 38 sliding against the inner cylindrical face 23 of the base collar 22. There is sufficient clearance between the heat sink blades 204a, the inner annular trim 38 and the inner cylindrical face 23 to ensure that friction is negligible. The mouth 62a, 62b of each channel 60a, 60b is aligned with a respective pin 50a, 50b of the base collar 22. If the mouths 62a, 62b are not correctly aligned with the pins 50a, 50b, the installer, relying on trial and error, rotates the support collar 32 about longitudinal axis X-X until they are. Each pin 50a, 50b slides into a respective mouth 62a, 62b. The mouths 62, 62b cannot continue very far in the up direction of arrow A because in a short distance the pins 50a, 50b arrive at the first U-bend.

Referring in particular to Figure 6, operation of the adjustable coupling mechanism shall be described from the point at which the pins 50a,50b engage the mouths 62a,62b. For brevity, only engagement between the pin 50a and parts of the channel 60a in the heat sink blades 204a are described from here, however this part of the description applies equally to the other pin 50b and the other channel 60b in the heat sink blades 204a. Note that the pin 50a could enter the mouth 62b and the pin 50b could enter the mouth 62a and the adjustable coupling mechanism would work the same.

The installer manually pushes the support collar 32 in the up direction A causing the pin 50a to slide in the down direction B in relation to the channel 60a. The pin 50a soon meets the first U-bend 64a which guides the support collar 32 to rotate gently in the anti-clockwise direction R'. The pin 50a gently rotates in the clockwise direction R in relation to the channel 60a and up (a small way in the direction of arrow A) into the first recess 66a, as is shown by arrow C. The installer may release the support collar 32 when the pin 50a is engaged with the first recess 66a because gravity keeps them engaged. The trough of the first U-bend 64a acts as a detent to retain the pin 50a in the first recess 66a against rotation in either the clockwise direction R or the anti-clockwise R' direction. The luminaire 200 is stably supported in its most extended position with the outer annular trim 36 of the support collar 32 generally flush with the outer end 22a of the base collar 22, as is shown in Figure 1.

The installer may decide that the luminaire 200 should be retracted a small way within the base collar 22. If so, the installer manually pushes the support collar 32 again in the up direction A causing the pin 50a to slide along the second drop 72a in the down direction B in relation to the channel 60a. The pin 50a soon meets the second U-bend 74a which guides the support collar 32 to rotate gently in the anti-clockwise direction R'. The pin 50a gently rotates in the clockwise direction R in relation to the channel 60a and up (a small way in the direction of arrow A) into the second recess 76a, as is shown by arrow D. The installer may release the support collar 32 when the pin 50a is engaged with the second recess 76a because gravity keeps them engaged. The trough of the second U-bend 74a acts as a detent to retain the pin 50a in the second recess 76a against rotation in either the clockwise direction R or the anti-clockwise R' direction. The luminaire 200 is stably supported in its second most extended position with the outer annular trim 36 retracted within the outer end 22a of the base collar 22 by a distance equivalent to the axial distance between the first 66a and second 76a recesses.

Again, the installer may decide that the luminaire 200 should be further retracted a small way within the base collar 22. If so, the installer manually pushes the support collar 32 again in the up direction A causing the pin 50a to slide along the third drop 82a in the down direction B in relation to the channel 60a. The pin 50a soon meets the third U-bend 84a which guides the support collar 32 to rotate gently in the anti-clockwise direction R'. The pin 50a gently rotates in the clockwise direction R in relation to the channel 60a and up (a small way in the direction of arrow A) into the third recess 86a, as is shown by arrow E. The installer may release the support collar 32 when the pin 50a is engaged with the third recess 86a because gravity keeps them engaged. The trough of the third U- bend 84a acts as a detent to retain the pin 50a in the third recess 86a against rotation in either the clockwise direction R or the anti-clockwise R' direction. The luminaire 200 is stably supported in its middle position with the outer annular trim 36 retracted mid way between is most extended and most retracted positions by a distance equivalent to the axial distance between the first 66a and third 86a recesses.

Once again, the installer may decide that the luminaire 200 should be further retracted a small way within the base collar 22. If so, the installer manually pushes the support collar 32 again in the up direction A causing the pin 50a to slide along the fourth drop 92a in the down direction B in relation to the channel 60a. The pin 50a soon meets the fourth U-bend 94a which guides the support collar 32 to rotate gently in the anti-clockwise direction R'. The pin 50a gently rotates in the clockwise direction R in relation to the channel 60a and up (a small way in the direction of arrow A) into the fourth recess 96a, as is shown by arrow F. The installer may release the support collar 32 when the pin 50a is engaged with the fourth recess 96a because gravity keeps them engaged. The trough of the fourth U-bend 94a acts as a detent to retain the pin 50a in the fourth recess 96a against rotation in either the clockwise direction R or the anticlockwise R' direction. The luminaire 200 is stably supported in its second most retracted position with the outer annular trim 36 retracted within the outer end 22a of the base collar 22 by a distance equivalent to the axial distance between the first 66a and fourth 96a recesses.

Finally, the installer may decide that the luminaire 200 should be fully retracted within the base collar 22. If so, the installer manually pushes the support collar 32 again in the up direction A causing the pin 50a to slide along the fifth drop 102a in the down direction B in relation to the channel 60a. The pin 50a soon meets the fifth U-bend 104a which guides the support collar 32 to rotate gently in the anti-clockwise direction R'. The pin 50a gently rotates in the clockwise direction R in relation to the channel 60a and up (a small way in the direction of arrow A) into the fifth and final recess 106a, as is shown by arrow G. The installer can rotate no more because the fifth recess 106a is a dead end and its acts as a stop. The installer may release the support collar 32 when the pin 50a is engaged with the fifth recess 106a because gravity keeps them engaged. The trough of the fifth U-bend 104a acts as a detent to retain the pin 50a in the fifth recess 106a. The luminaire 200 is stably supported in its most retracted position with the outer annular trim 36 retracted within the outer end 22a of the base collar 22 by a distance equivalent to the axial distance between the first 66a and fifth 106a recesses. This is as shown in Figure 3.

In sliding and rotating between its various extended, midpoint and retracted positions, the luminaire 200 follows a generally helical path HP defined by the first 66a, second 76a, third 86a, fourth 96a and fifth 106a recesses in the channel 60a. The most retracted position is located behind the most extended position (in the direction of arrow A) by as much as the axial distance between the first 66a and the fifth 106a recesses which, in the present example, is

approximately 30mm.

The light fitting 10 may be disassembled by reversing the assembly method described above. Disassembly may be initiated by an installer at any one of the extended, midpoint or retracted positions. Initially, the installer gently moves the support collar 32 in the direction of arrow A until the pin 50a disengages whichever recess 66a, 76a, 86a, 96a, 106a it was previously in engagement with and rotates the support collar 32 in the clockwise direction R. The pin 50a slides along the channel 60a until ether the pin 50a exists the mouth 62a of the channel 60a or the pin 50a engages with another recess 66a, 76a, 86a, 96a further up the helical path HP than the recess 76a, 86a, 96a, 106a with which it was previously in engagement with. Once the pin 50a leaves the mouth 62a, the luminaire 200 is decoupled from the base 20.

The axial distance between the recesses 66a, 76a, 86a, 96a, 106a of the adjustable coupling mechanism and/or the circumferential distance between these recesses may be varied according to the particular size or application of the luminaire 200. Likewise, each channel 60a, 60b may have fewer or more than five recesses to provide fewer or more retracted positions behind the extended position. Ideally, although not necessarily, such variations may have consecutive recesses of each channel that define a substantially helical path HP about the circumference of the heat sink 204 so that smooth adjustment of the adjustable coupling mechanism is preserved.

The adjustable coupling mechanism described above may smoothly couple, decouple and adjust the luminaire 200 in relation to the base 20. This is achievable within the sweep of the helical path HP which is equivalent to the circumferential sweep between the fifth recess 106a and the mouth 62a of each channel (i.e. angle of approximately 30 to 60 degrees). This allows adjustment of the position of the luminaire 200 without any significant twist to the electrical power supply cables attached to the luminaire 100. The U-bends 64a, 74a, 84a, 94a, 104a leading to the recesses in the channels provide a tactile indication to the installer of when the luminaire has reached one of the extended, midpoint or retracted positions. Referring to Figure 7, the luminaire 200 may be surrounded by an alternative heat sink 204' connected to the body 202a. The alternative heat sink 204' has substantially the same outer and inner dimensions as the heat sink 204 and the two components are interchangeably connectable to the body 202a of the luminaire 200. The alternative heat sink 204' may be integral with the luminaire 200. The alternative heat sink 204' may be thermally coupled to the optical elements 202b-202d to help dissipate heat energy from the light source 202b and maintain the luminaire 200 at or below maximum operational temperature.

The alternative heat sink 204' has a generally cylindrical outer shape which is defined by an array of blades 204'a each of which is generally parallel to the longitudinal axis X-X. Each of the blades 204 'a has a curvilinear outer face 204 'b arranged at the outer circumference of the alternative heat sink 204'. Each of the blades 204 'a has an irregular cross-sectional shape 204 'c protruding inwardly towards the longitudinal axis X-X. The irregular cross- sectional shape increases the surface area of each blade 204 'a. Arranged between alternatively between the blades 204 'a are square, or rectangular, cross-section rods 204 'd also generally parallel to the longitudinal axis X-X. Arranged within the cylindrical array of blades 204'a are three concentric circular arrays of cylindrical fingers 204'e, 204'f, 204'g all of which are orientated generally parallel to the longitudinal axis X-X. The most central array of fingers 204'g surrounds a central port in the alternative heat sink 204' which provides access for electrical cables to the luminaire 200.

The outer faces 204 'b of the heat sink blades 204'a have the same outer diameter as the outer 36 and inner 38 annular trims of the support collar 32 (outer 36 and inner 38 annual trims not being shown in Figure 7). The alternative heat sink 204', the blades 204'a, the rods 204'd and the fingers 204'e, 204'f, 204'g may be made of any suitable metal, ceramic, plastic, fibre glass or composite material provided it is fire retardant and it has good heat conduction properties.

The heat sink 204 and the alternative heat sink 204' are two designs, amongst many, of heat sinks which have a high surface area to volume ratio to ensure heat dissipation properties that are superior to what would be achieved by the luminaire 200 alone.

The alternative heat sink 204' has a pair of generally staircase- shaped channels 60'a,60'b formed by, for example, molding, laser cutting or machining, in the outer faces 204'b of the blades 204'a to face the inner cylindrical surface 23 of the base collar 22. The channels 60'a,60'b are on diametrically opposite sides of the alternative heat sink 204' from each other. One pin 50a may engage one channel 60 'a and the other pin 50b may engage the other channel 60 'b. A difference between the channels 60a, 60b of the heat sink 204 and those of the alternative heat sink 204' is that the alternative heat sink channels 60 'a, 60 'b each comprise four pairs of U-bends and recesses instead of five pairs. Accordingly, with the alternative heat sink 204', the luminaire 200 may be stably supported in four different positions within the outer end 22a of the base collar 22 rather than five.

In an alternative adjustable coupling mechanism, the pins 50a,50b may be located on the heat sink 204, or the alternative heat sink 204', and the channels 60a,60b may be located somewhere on the base 20. In another alternative adjustable coupling mechanism, the channels 60a,60b may be located on the support collar 32 (enlarged in an axial direction to accommodate the channels 60a,60b) or another part of the luminaire 200.

The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention.