GB2497925A

GB2497925A - LED light fittings

Info

Publication number: GB2497925A
Application number: GB1121937.5A
Authority: GB
Inventors: Daniel Hodgson
Original assignee: AC DC LED Ltd
Current assignee: AC DC LED Ltd
Priority date: 2011-12-20
Filing date: 2011-12-20
Publication date: 2013-07-03
Anticipated expiration: 2031-12-20
Also published as: GB2497925B; GB201121937D0

Abstract

A recessed light fitting 10 has a mount 12, a light source 14 which can move or pivot relative to the mount 12 and an adjustable lock (52, 62, fig 4) to lock the light 14 at a desired angle relative to the mount 12. The lock (52, 62, fig 4) may be a gear assembly (54, 56).

Description

Title: LED light fittings

Description:

This invention relates to LED light fittings, and in particular to recessed LED light fittings.

The use of LED lighting, as a replacement for conventional filament lighting, is on the increase owing primarily to the improved energy efficiency of LED light fittings compared to their filament lighting counterparts. In recent years, significant advances have been made in the manufacture of LEDs meaning that high-intensity, high-efficiency LEDs can now be mass produced relatively cheaply. As a result, the use of LED lighting is now a viable alternative to conventional filament lighting.

A typical LED light fitting comprises a circuit board having a number of surface-mount LEDs thereon and a lens disc positioned in front of the LEDs comprising a number of lens elements that are aligned with the individual LEDs to produce a desired beam pattern. Most LEDs require a transformer or driver to convert AC mains power into an appropriate constant-current, DC power supply for the LEDs. The transformer or driver can be built into a light fitting, such that the light fitting can be connected directly to a mains power supply. In most cases, however, a number of LED light fittings are connected to a common transformer or driver such that there is just one mains power connection delivering DC current to a number of LED light fittings.

Hi-power LEDs have a relatively high operating temperature, that is to say in the range of 40°C to 80°C and so require a cooling system to be incorporated into the light fitting to prevent the LEDs from overheating. The cooling system can be an "active" cooling system, that is, comprising a heatsink in thermal contact with the LED5 and a tan adapted to blow air over the heatsink to extract heat from the LEDs.

Active cooling systems for LED light fittings tend to be used only in specialised situations because the fan consumes electrical power and also emits noise, which can be irritating in certain situations. An alternative to an "active" cooling system is a "passive" cooling system, which uses a much larger heatsink that is capable of cooling the LEDs, that are thermally connected to it, by passive air convection. In many cases, the individual LEDs of the light fitting are thermally connected to a common heatsink by so-called "heat pipes", which are hollow tubes containing a fluid having a relatively low boiling point. A heat pipe works by transferring heat away from the LEDs in contact with one end of the tube by evaporation of the fluid within the tube at that end: the vaporised fluid moving along the tube and condensing at the other end of the tube in contact with the heatsink, which is maintained at a lower temperature than that of the LEDs. Heat is, in effect, transferred long tube by absorbing heat and emitting heat at opposite ends of the tube through the respective latent heat of evaporation and sublimation. The operation of heat pipes is well known to those skilled in the art does not require detailed explanation here.

Needless to say, an active cooling system is relatively heavy because of the weight of the heatsink, the fan and associated circuitry. In addition, a passive cooling system is also relatively heavy because of its much larger, and hence heavier, heatsink and because of the presence of the heat pipes.

In a conventional LED lighting system, the cooling system is located behind the circuit board upon which the LEDs mounted, which leads to the mass distribution of components of the light fitting being uneven.

In many cases, it is desirable for the LED light fitting to be tiltable and/or rotatable to enable the beam of light emitted by the light fitting to be directed in a particular direction. This can be accomplished by forming the light fitting in two parts, namely a fixing portion, which is a fixedly affixable to a wall or ceiling, and a lighting portion, which comprises the LEDs, heatsink and circuitry: the fixing portion and the lighting portion being relatively movable.

In a conventional filament light fitting, the weight of the bulb is insignificant compared to that of the light fitting itself. However, in an LED light fitting, the weight of the LED circuit board, its lenses, the cooling system and associated circuitry can be quite significant. If the LED light fitting is arranged such that it is aligned with a vertical axis, it will tend to remain in that position indefinitely. However, where the light fitting is tilted, that is to say the centre of gravity of its lighting portion does not coincide vertically with the pivot point, there can be a tendency for the light fitting to "creep" over time, meaning that the tilt angle can change unintentionally.

In order to address this problem, most LED light fittings have a high friction pivot point such that the tilting moment of the light fitting is counteracted by the friction in the pivot. In many situations, such an arrangement can maintain the light fitting as the desired tilt angle over extended periods of time. On the other hand, many tiltable recessed light fittings are located in ceilings, which have a floor above them. As such, it is quite common for the ceiling which the light fitting is located to vibrate under the influence of footfall and other movement on the floor above. This vibration can, in many situations, be sufficient to overcome the frictional force preventing movement of the light fitting, thereby allowing the light fitting to "creep" overtime, to an unintended tilt angle.

Furthermore, when architects and interior designers design a lighting scheme for a building, they often specify particular tilt angles for light fittings to achieve a desired lighting effect. The tilt angles are often specified in advance and it is up to the installer to ensure that each light fitting is positioned correctly prior to leaving the site. In a situation where there are a number of light fittings that must be oriented at particular angles, for example when creating a "wall wash" lighting effect, even small differences in the tilt angles of the light fittings can have a large impact on the lighting effect produced. A great deal of time may therefore be spent adjusting, correcting and readjusting the angles of a number of light fittings, which can introduce unwanted delay into the installation process.

A need therefore arises for a new type of recessed light fitting that addresses one or more of the above problems and/or which provides improved recessed light fitting, in particular an improved recessed LED light fitting.

According to a first aspect of the invention there is provided a recessed light fitting comprising a mounting portion, a light portion moveable relative to the mounting portion and an adjustable locking means for locking the light portion at a desired angle relative to the mounting portion.

The light portion may be pivotally and/or rotationally moveable relative to the mounting portion.

By providing an adjustable locking means, the tilt angle or rotation of the light portion relative to the mounting portion may be locked at a desired angle, which may prevent or inhibit creep of the tilt angle, or rotation of the light fitting, over time.

Additionally or alternatively, the provision of an adjustable locking means may enable the tilt angle or rotation of the light portion relative to the mounting portion to be pre-set, for example, at the factory, or by an installer prior to installation, thereby ensuring consistency of to the tilt angle or rotation of a number of light fittings. The ability to pre-set or "dial-in" a desired tilt angle prior to installation of the light fitting may enable the amount of post-installation adjustment needed to be reduced or eliminated.

As such, the invention may address some or all of the problems associated with known, tiltable and/or rotatable recessed light fittings, in particular those in which the tilt angle and/or rotation is maintained by friction alone.

In a preferred embodiment of the invention, the light portion of the light filling may be rotatable relative to the mounting portion thereof, in addition, or alternatively, to being pivotally tillable relative thereto. Where the light portion of the light fitting is rotatable relative to the mounting portion thereof, an adjustable locking means may be provided for locking the light portion at a rotational angle relative to the mounting portion.

The ability to adjust and lock the rotational relationship between the light portion and the mounting portion may enable the rotation of the light fitting to be maintained over extended periods of time. In addition, or alternatively, the provision of a light fitting having an adjustably-lockable rotation may enable the rotation of the light portion relative to the mounting portion to be pre-set, for example, at the factory, or by an installer prior to installation, thereby ensuring consistency of to the rotation of a number of light fittings. The ability to pre-set or "dial-in" a desired rotation prior to installation of the light fitting may enable the amount of post-fristallation adjustment needed to be reduced or eliminated.

The adjustable locking means preferably comprises an adjustable, mechanical connection between the mounting portion and the light portion of the light fitting. The mechanical connection between the mounting portion and the light portion of the light fitting may comprise gears. In particular, the gears may comprise a worm screw arranged to engage with a radial gear, which arrangement effectively locks radial gear relative to the worm screw, but nevertheless enables the radial gear to be rotated by rotation of the worm screw. The gear ratio of the worm screw and radial gear is preferably high. It will be readily appreciated that a worm screw-radial gear arrangement permits relatively uninhibited movement of the radial gear by rotation of the worm screw, but effectively inhibits movement of the work screw by rotation of the radial gear because of the high gear ration between the two.

Frictional engagement means may be provided to inhibit rotation of the worm screw.

The gears may additionally, or alternatively comprise an annular gear and a pinion gear having a relatively high gear ratio such that rotation of the annular gear is effectively locked, but can nevertheless be rotated by rotation of the pinion gear.

Frictional engagement means may be provided to inhibit rotation of the pinion gear.

Preferred embodiments of the invention shall now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a perspective view from above of a first embodiment of a recessed light fitting in accordance with the invention; Figure 2 is a side view of the recessed light fitting of Figure 1; Figures 3 and 4 are perspective views from below of a portion of the recessed light fitting of Figures 1 and 2; Figure 5 is an exploded view of Figures 3 and 4; Figure 6 is a perspective view from above of a second embodiment of a recessed light fitting in accordance with the invention; and Figure 7 is a perspective view from above of a third embodiment of recessed light fitting in accordance with the invention.

In Figures ito 7, a recessed light fitting 10 in accordance with the invention is shown, which comprises a mounting portion 12 and a light portion 14. The light portion 14 is pivotally connected to the mounting portion 12 by a pair of diametrically opposed pins 16, which enable the light portion 14 to be pivoted about pins 16 relative to the mounting portion 12. The tilt angle 18 is lockably adjustable as shall be described below. The light portion 14 of the light fitting 10 can also be rotated relative to the mounting portion 12 about an axis 20 and the angle of rotation 22 can also be lockably adjusted in a manner described below. As such, the recessed light fitting 10 of the invention comprises a light fitting having a light portion 14 that can be tilted, and optionally rotated, relative to the mounting portion 12.

The mounting portion 12 of the light fitting shown in figures 1 and 2 comprises a generally square-shaped sleeve 24 having a peripheral flange 26 that can be inserted into a pre-cut aperture in a plenum wall or ceiling in a known manner. The sleeve 24 comprises a spigot portion 28 that nests inside the side wall of the precut aperture (not shown) in the wall or ceiling and the light fitting 10 is prevented from being inserted into the aperture beyond a desired extent by the flange portion 26, which abuts the outer surface of the wall or ceiling into which the light fitting 10 inserted. The light fitting 10 is retained in situ by four spring-loaded clips 30 that can be bent to fit through the precut aperture, but which spring back to engage the rear surface of the plenum wall or ceiling into which the light fitting 10 inserted. The underside of the mounting portion 12 (not visible) may optionally be provided with reflective portions and/or a decorative fascia that can be integrally formed with the mounting portion 12, or which can be affixed thereto subsequent to installation of the light fitting 10 using magnets, clips or other mechanical fastneners. The mounting portion 12 is of a generally conventional design that will be familiar to persons skilled in the art.

The light portion 14 of the light fitting 10 comprises a main chassis portion 32 having a pair of legs 34 extending downwardly therefrom. The legs 34 have through apertures at their distal ends through which the pivot pins 16 extend to enable the chassis 32 to pivot relative to the mounting portion 12.

The main chassis portion 32 comprises a radially inwardly extending internal annular flange (not visible) to which a circuit board (not shown) can be mounted, which circuit board carries the LEDs of the light fitting 10, which is overlaid by a lens disc, which is also not shown clarity. The LED5 (not shown) are cooled by passive cooling system comprising a heatsink 36, which is connected to, and which extends rearwardly from, the main chassis portion 32. The heatsink 36 comprises an aluminium extrusion have a number of cooling fins, which enable heat to be dissipated from the LEDs by passive air convection. The weight of the heatsink 36 causes the centre of gravity 38 of the pivotally movable light portion 14 to be spaced apart from the pivot point 16. As such, when the light portion 14 is tilted relative to the mounting portion 14, the location of the centre of gravity 38 is laterally offset 40 relative to the pivot point 16, which gives rise to a tilting moment that tends to urge the angle of the light portion 14 away from the vertical.

In a conventional light fitting, the pivot pins 16 would be provided in the form of screws that enable the legs 34 of the chassis 32 to be tightened to the mounting portion 12 of light fitting 10, thereby inhibiting inadvertent tilting of the light portion 14 away from a desired tilt angle 18. However, when a known light fitting is subject to vibration, the frictional engagement of the legs 34 to the mounting portion 12 can be temporarily and/or intermittently overcome leading to "creep" of the tilt angle 18 over time.

As can be seen in particular in Figure 4, the invention, by contrast with the prior art, comprises an adjustable locking means 50 interposed between the chassis 32 of the light portion 14 and the mounting portion 12.

The adjustable locking means 50 comprises a worm screw 52 that intermeshes with a partial radial gear 54 formed radially about the pivot pins 16 at the lower end of one of the legs 34 of the chassis 32. Rotation of the worm screw 52 causes rotation of the partial radial gear 54 about the pivot pin 16, thereby causing the tilt angle 18 of the chassis 32, and hence the light portion 14 light fitting 10 to be adjustable. The end of the worm screw 52 is accessible through an aperture in the front of the light fitting 10 and comprises a cross-shaped recess for receiving the tip of a suitable screwdriver. Such an arrangement enables the worm screw 52 to be rotated using a screwdriver to adjust the tilt angle 18 of the light portion 14 relative to the mounting portion 12. Because the worm screw 52 is accessible from without the light fitting 10, it is possible to adjust the tilt angle 18 with the light fitting 10 in-situ, or to pre-adjust the tilt angle 18 prior to installation the light fitting 10. As such, the tilt angle 18 can be pre-set, either at the factory or immediately prior to installation, and the tilt angle can be easily adjusted andlor corrected, if required, once the light fitting 10 has been installed.

It will be appreciated that the gear ratio of a worm gear arrangement is relatively high and that the worm gear arrangement 50 essentially locks the angle of the chassis 32 relative to the mounting portion 12 unless the worm screw 52 is intentionally rotated by operator.

Turning now to Figure 3 of the drawings, it will be seen that the chassis 32 is connected to the mounting portion 12 of the light fitting 10 via an annular ring 55, which slides atop an annular gear ring 56. Depending downwardly from the annular ring 55 of the chassis portion 32, there is provided a bearing sleeve 58, which carries an axially-rotatable axle 60 whose lower end terminates in a pinion gear 62. The pinion gear 62 has a cross-shaped formation, which is accessible from without the light fitting 10, thereby enabling the pinion gear 62 to be rotated using a screwdriver.

Rotation of the pinion gear 62 causes the bearing sleeve 58 to rack around the annular gear ring 56 pulling the annular ring 55 and chassis 32 with it. As such, rotation of the pinion gear 62 causes the rotational relationship between the chassis 32, and hence the tiltable light portion 14 of the light fitting 10 to be adjustable relative to the mounting portion 12 of the light fitting 10.

It will be readily appreciated, therefore, that the tilt angle 18 and rotation 22 of the light portion 14 of the light fitting 10 relative to the mounting portion 12 can be lockably adjusted by an operator. This affords a great deal of versatility in the orientation of the light emitted from the light portion 14 and overcomes some, or all, of the problems highlighted above.

Figure 5 is an exploded view of Figures 3 and 4 and shows the various components of the lockable adjustment mechanisms of the light fitting 10. In Figure 5, it will be noted that a torsion spring 64 is used to bias the chassis 32 towards a non-vertical tilt angle, thereby ensuring that the teeth of the worm screw 52 and the partial radial gear 54 and maintained in intimate contact. The tension of the torsion spring 64 also frictionally engages the teeth of the worm screw 52 with those of the radial gear 54, which means that a minimal resistive rotational force is built into the worm screw 52, which must be overcome before it can be rotated. This feature inhibits or prevents inadvertent rotation of the worm screw, and hence inadvertent adjustment of the tilt angIe 18.

It will also be noted that the axle 60 of the rotational adjustment mechanism is held in place by a screw 68 that screw-threadedly engages with an axial blind hole (not visible) in the end of the axle 60. Interposed between the screw 68 and the bearing sleeve 58 is an elastomeric, frusto-conical bush 70 which frictionally locks the rotational orientation of the axle 60 relative to the bearing sleeve 58. In a similar manner to that described above in relation to the torsion spring 64, the elastomeric bush 70 builds-in a minimum rotational force that must be overcome before the pinion gear 62 can be rotated, which inhibits or prevents inadvertent rotation of the pinion gear, and hence inadvertent adjustment of the rotation of the light portion 14 relative to the mounting portion 12.

In Figures 6 and 7 it can be seen that the same chassis and locking components described in relation to Figures 1 to 5 can be used in a range of light fittings. In particular, in Figure 6, the light fitting 10 as a generally circular fascia 72 that can be installed into a circular aperture in a plenum wall or ceiling. In such a situation, it is not necessary to enable the light portion 14 to rotate relative to the mounting portion 12 because the rotational orientation of the light can be adjusted by bodily rotating the entire light fitting 10 within the receiving aperture in the plenum wall or ceiling. As such, the light fitting shown in figure 6 only has a lockable adjustable tilt angle and the annular gear 56 and pinion gear 62 described above has been omitted.

Finally, in Figure 7, a smaller version of the square light fitting described in relation to Figures 1 to 5 shown: the mechanical components of the light fitting of Figure 7 being essentially the same as those described above, albeit a scaled version thereof. As such, it will be appreciated that the invention is not restricted to particular shapes or sizes of light fitting 10, but can be adapted to be implemented in a range of light fittings. The versatility of the locking system, that is to say, the fact that a common adjustable locking system can be applied to a range of light fittings of different designs, enables the lockably-adjustable tilt and/or rotation mechanism to be mass produced relatively cheaply and/or to be deployed across a wide range of light fittings.

The invention is not restricted to the details of the foregoing embodiments, which are merely exemplary of preferred embodiments of the invention. In particular, the shape, configuration and materials of the various components of the invention can be varied without departing from the scope of the invention. In addition, although the invention is particularly applicable to recessed LED light fittings, it is not restricted thereto, for example, it could equally be applied to conventional filament light bulb systems or other light fittings that are not of the recessed type.

Claims

<claim-text>Claims: 1. A light fitting comprising a mounting portion, a light portion moveable relative to the mounting portion and an adjustable locking means for locking the light portion at a desired angle relative to the mounting portion.</claim-text> <claim-text>2. A light fitting as claimed in claim 1, wherein the light portion is pivotally moveable relative to the mounting portion.</claim-text> <claim-text>3. A light fitting as claimed in claim 1 or claim 2, wherein the light portion is rotationally moveable relative to the mounting portion.</claim-text> <claim-text>4. A light fitting as claimed in any of claims 1 to 3, wherein the adjustable locking means comprises an adjustable, mechanical connection between the mounting portion and the light portion of the light fitting.</claim-text> <claim-text>5. A light fitting as claimed in claim 4, wherein mechanical connection between the mounting portion and the light portion of the light fitting comprise gears.is 6. A light fitting as claimed in claim 5, wherein the gears comprise a worm screw arranged to engage with a radial gear.7. A light fitting as claimed in claim 5, wherein the gears comprise an annular gear and a pinion gear.8. A light fitting as claimed in claim 6 or claim 7, wherein the gear ratio of the worm screw and radial gear is high.9. A light fitting according to any preceding claim, wherein the light portion is pivotally connected to the mounting portion.1O.A light fitting as claimed in claim 9, wherein the light portion comprises a main chassis portion having a pair of legs extending downwardly therefrom, the legs having through apertures at their distal ends through which pivot pins extend to enable the chassis to pivot relative to the mounting portion.11.A light fitting as claimed in claim 10, wherein the adjustable locking means comprises a worm screw that intermeshes with a partial radial gear formed radially about the pivot pins at the lower end of one of the legs of the chassis.12.A light fitting according to any preceding claim, wherein the light portion is rotatably connected to the mounting portion.13.A light fitting as claimed in claim 12, wherein the light portion comprises a chassis connected to the mounting portion via an annular ring, the annular ring being adapted to slides relative to an annular gear.14.A light fitting as claimed in claim 13, further comprising a bearing sleeve extending from the annular ring, which carries an axially-rotatable axle whose lower end terminates in a pinion gear, the teeth of the pinion gear being arranged intermesh with the teeth of the annular gear.15.A light fitting as claimed in claim 11 or claim 14, wherein end of the worm screw or pinion gear is accessible through an aperture in the front of the light fitting.16.A light fitting as claimed in claim 15, wherein the worm screw and/or pinion gear comprises a cross-shaped recess for receiving the tip of a screwdriver.17.A light fitting as claimed in any of claims 11 to 16, further comprising supplementary frictional engagement means for inhibiting rotation of the worm screw or pinion gear.18.A light fitting as claimed in claim 17, wherein the supplementary frictional engagement means comprises a torsion spring adapted to bias the chassis towards a non-vertical tilt angle, or a resiliently deformable bush for frictionally locking rotational orientation of the pinion gear relative to the bearing sleeve.19.A recessed light fitting according to any preceding claim.20.A recessed light fitting as claimed in claim 19, wherein the mounting portion comprises a sleeve that can be inserted into a pre-cut aperture in a plenum wall or ceiling, a peripheral flange adapted to prevent the light fitting from being inserted into the pre-cut aperture beyond a desired extent and clips that can be bent, in use, to fit through the pre-cut aperture, but which are adapted to spring back to engage the rear surface of the plenum wall or ceiling into which the light fitting inserted.21.A light fitting as claimed in any preceding claim, wherein the mounting portion further comprises a reflector and/or a decorative fascia.22.A light fitting as claimed in claim 21, wherein the reflector and/or decorative fascia are integrally formed with the mounting portion, or which can be affixed thereto using any one or more of the group comprising: magnets; clips; and mechanical fasteners.23.An LED light fitting according to any preceding claim.24An LED light fitting as claimed in claim 23, further comprising any one or more of the group comprising: a circuit board carrying the LEDs of the light fitting; a lens disc; a passive cooling system; a heatsink; and a heat pipe.25.A light fitting, recessed light fitting or LED light fitting substantially as hereinbefore described, with reference to, and as illustrated in, the accompanying drawings.</claim-text>