AU2011101336A4 - Downlight Lens - Google Patents

Abstract

A downlight fixture comprising, a mounting ring configured to mount the downlight fixture in a hole; means for supporting a lamp socket above the mounting ring; a ring plate detachable mounted underneath the mounting ring, the ring plate defining an aperture; and a lens positioned at least partly across the aperture, wherein the lens is adapted to deflect at least some light incident on the lens from above in one or more sideways directions. Figure 1

Description

1 DOWNLIGHT LENS Field of Invention The invention relates to lenses for downlights. In particular, the invention relates to a downlight fixture comprising a wall washing lens. Background to the Invention Downlights are ceiling-mounted lighting fixtures that can be recessed into a ceiling cavity and shine downwards into a room. Downlights have become widespread because they are a stylish source of effective lighting. They are also unobtrusive because they do not protrude into a room to the extent of other types of light fixture. Downlights are used in many different situations, including residential and commercial buildings. They can be installed in both new and existing constructions by mounting in a ceiling panel or other ceiling installation. Conventional downlight fixtures include a mounting ring for mounting the downlight in a hole in a ceiling and a structure that supports a lamp socket above the centre of the mounting ring. Downlight fixtures often also include a lamp housing (sometimes known as a reflector) with a reflective inner surface to channel light downwards into a room. In many downlight fixtures, the lamp housing is held in place, at least in part, by a bezel structure in the mounting ring. Often, the mounting ring includes a detachable ring plate which forms the ring part of the bezel structure. The lower surface of the ring plate is usually intended to be the only part of the light fitting that is visible from the room when installed. The ring plate may be detachable so that the lamp housing can be removed from the fixture. It may be necessary to remove the lamp housing for maintenance purposes or, for example, to give access to a mechanism holding the downlight fixture in place in the ceiling so that the fixture can be removed. It is sometimes desirable to cause downlights located near a wall of a room to shine against the wall rather than straight down. This so-called "wall washing" effect lightens the walls, thereby giving the impression of a lighter room. Existing downlights achieve the wall washing effect in a 2 number of ways, including pivotal rotation of the lamp inside the downlight fixture so that the lamp points towards the wall, and reflectors which divert light against the wall. These arrangements may result in too much of a lamp's light being shone on the wall, depriving light from other parts of a room. Downlight fixtures that are pivoted towards a wall may result in a portion of the downlight extending below the plane of the ceiling, which adversely affects the aesthetics of downlights. Pivoted downlights can also be moved away from the desired position which, while convenient in some cases, may not always be so. Light fixtures of various types are commonly fitted with a device for modifying the light emitted by the light fixture. Examples of such a device are lenses or diffusers. A lens modifies the direction of at least some of the light passing through it. A diffuser softens the light and spreads the light out through a room. Commonly seen diffusers comprise a panel of acrylic sheeting placed in a ceiling panel below a fluorescent light. Such diffusers are frequently used in large buildings having panelled ceilings such as offices, supermarkets, hospitals and the like. Lighting diffusers often comprise a structure responsible for the diffusion of light. Common diffusion structures are arrays of prisms, concave or convex forms on the surface of the diffuser. Light is diffused by means of the cumulative effect of light refraction through the non-planar surface of the diffuser. Other types of diffuser comprise frosted glass or other semi-transparent material. It is an object of the invention to provide a downlight fixture able to produce a wall washing effect that addresses at least some of the disadvantages associated with the prior art, discussed above. It is alternatively an object of the invention to at least provide the public with a useful choice. Summary of the Invention According to a first aspect of the invention there is provided a lens for a downlight fixture comprising means for engaging the lens with the downlight fixture wherein the lens is adapted to deflect at least some light incident on the lens from above in one or more sideways directions. The term "lens" as used herein refers to any device or arrangement of devices that functions to modify the direction in which light travels as light passes through the lens.

3 Preferably, the lens is suited for use as a wall washing lens. More preferably, the lens deflects light in substantially a single sideways direction. In one embodiment, the lens may comprise a means of diffusing light, or diffuser. The term "diffuser" as used herein refers to a semi-transparent or translucent component that diffuses, spreads or scatters light passing through the diffuser in some manner. Preferably, the lens is adapted to deflect light by refraction. Preferably, the lens comprises an array of prisms in parallel alignment. More preferably, the prisms each comprise two upper surfaces angled relative to each other. Preferably, the angle of a first upper surface of each prism changes gradually along the array of prisms. Preferably, a lower surface of the lens is substantially planar. More preferably, in use, the lower surface of the lens is substantially co-planar with a lower surface of the downlight fixture. Preferably, in use, the lens is adapted to cover an aperture in the downlight fixture. In a preferred embodiment of the invention, the lens comprises one or more flange portions adapted to engage with the downlight fixture. According to a second aspect of the invention, there is provided a downlight fixture comprising: a mounting ring configured to mount the downlight fixture in a hole; means for supporting a lamp socket above the mounting ring; a ring plate detachably mounted underneath the mounting ring, the ring plate defining an aperture; and a lens positioned at least partly across the aperture, wherein the lens is adapted to deflect at least some light incident on the lens from above in one or more sideways directions. It will be understood that the term "ring plate" as used in this specification relates to a component having a ring-shaped, generally planar body. Both the aperture and the body may 4 be any shape. In many preferred embodiments, the ring plate will be circular and define a circular aperture. However, in other embodiments, the ring plate may be other shapes, including square, and define an aperture of any shape. Preferably, the lens may comprise a means for diffusing light. Preferably, the lens is suited for use as a wall washing lens. More preferably, the lens deflects light in substantially a single sideways direction. Preferably, the lens is adapted to deflect light by refraction. Preferably, the lens comprises an array of prisms in parallel alignment. More preferably, the prisms each comprise two upper surfaces angled relative to each other. Preferably, the angle of a first upper surface of each prism changes gradually along the array of prisms. Preferably, a lower surface of the lens is substantially planar. More preferably, the lower surface of the lens is substantially co-planar with a lower surface of the ring plate. Preferably, the lens covers the entire aperture in the ring plate. Preferably, the lens is able to be removed from the downlight fixture when the ring plate is detached. In a preferred embodiment of the invention, the lens comprises one or more flange portions adapted to engage with an upper surface of the ring plate. More preferably, the ring plate forms a bezel structure for holding the lens in place. Preferably, the downlight fixture further comprises a lamp housing. The lamp housing may comprise reflective inner sides. In a preferred embodiment, the ring plate comprises projections on an upper side adapted to engage with the mounting ring. The mounting ring may comprise recesses on a lower side for 5 receiving the projections of the ring plate. More preferably, the ring plate is adapted to attach to the mounting ring by rotational movement of the ring plate relative to the mounting ring. Further aspects of the invention, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the invention. Brief Description of the Drawings One or more embodiments of the invention will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which: Figure 1 is an isometric cross-sectional view of a downlight fixture according to an embodiment of the invention; Figure 2 is a front cross-sectional view of the downlight fixture shown in Figure 1; Figure 3 is a back cross-sectional view of the downlight fixture shown in Figure 1; Figure 4 is an exploded isometric cross-sectional view illustration of parts of the downlight fixture illustrated in Figures 1 to 3; Figure 5 is a plan view illustration of the lens shown in Figures 1 to 4; Figure 6 is a side view illustration of the lens shown in Figure 5; and Figure 7 is an isometric cross-section view of a downlight fixture according to another embodiment of the invention. Detailed Description of Preferred Embodiments of the Invention In the following description, the invention will be described with reference to its use as a downlight in a ceiling. This is one common way the invention is expected to be used but it should be understood that this is not limiting to the invention. The "downlight" fixture that is the subject of the invention may be used in any situation, for example, it may be mounted in a wall, 6 floor or other building structure. Any reference to relative positional terms such as "above", "under" or the like when used in this specification should be understood to refer to the downlight fixture in a ceiling-mounted orientation and therefore are not limiting to the invention if the fixture is used in a different situation. First embodiment of a downright fixture according to the invention Figure 1 is an isometric cross-sectional view of a downlight fixture 10 according to an embodiment of the invention. Figures 2 and 3 are front and back cross-sectional views respectively of the downlight fixture 10 shown in Figure 1. Downlight fixture 10 comprises a mounting ring 11 configured to be inserted into a hole in a ceiling or other building structure to mount the downlight fixture. The hole preferably has substantially the same diameter as a rim 12 of mounting ring 11 such that the downlight fixture can be friction fitted in the hole. Mounting ring 11 may comprise a flange 13 on an outer edge. When mounted in a hole, flange 13 abuts the surface of one side of the building structure in which the hole is made. For example, flange 13 abuts the downward facing surface of the ceiling. Flange 13 limits the extent to which the downlight fixture can be inserted into the ceiling. The flange prevents the upward movement of the downlight in the hole over time, for example caused by vibrations. Mounting ring 11 is configured to receive a ring plate 21. Ring plate 21 provides a facia to the downlight fixture as seen from below. In the embodiment shown, the ring plate connects to mounting ring 11 by projections 15 of the ring plate engaging with slots 17 of the mounting ring. To attach ring plate 21 to mounting ring 11, the projections are inserted into slots 17 and rotational movement of ring plate 21 relative to mounting ring 11 causes the projections to engage therein. Downlight fixture 10 comprises means for supporting a lamp socket (not shown) above the mounting ring. In preferred embodiments, the lamp socket is supported approximately centrally above the mounting ring. The lamp socket may be adapted to receive an LED lamp, for example of the sort consisting of an array of individual LEDs, screw bulbs, bayonet bulbs, spotlights, halogen lights or any other light emitting device. In the embodiment shown, means for supporting a lamp socket comprises a lamp housing 16. Lamp housing 16 comprises a body in the shape of a hollow cylinder having tapering sides.

7 Lamp housing 16 may have a reflective interior surface to channel light downwards into the room, as is known in the art. For this reason, lamp housing 16 is commonly referred to as a reflector. However, the invention includes embodiments in which the interior surface of the lamp housing is not reflective. Figure 4 is an exploded isometric cross-sectional view illustration of parts of the downlight fixture illustrated in Figures 1 to 3. As shown in Figure 4, mounting ring 11 comprises means for frictionally holding lamp housing in place when positioned inside mounting ring 11. In the preferred embodiment shown in the figures, the means for frictionally holding lamp housing in place comprises one or more lugs 19 on the inner side of mounting ring 11. As shown in Figures 1 to 4, downlight fixture 10 comprises lens 20. Lens 20 is positioned at least partly across the aperture defined by ring plate 21, and preferably spans the entire aperture as shown in Figures 1 to 4. Lens 20 is adapted to deflect at least some light incident on the lens from above in a sideways direction, that is, a deflection in a direction perpendicular to the plane of the lens away from the path that light would take if the lens was not present. Lens 20 is mounted on downlight fixture 10 such that it can be removed if ring plate 21 is removed from mounting ring 11. In the embodiment shown in Figures 1 to 4, lens 20 comprises a flanged portion 22 which, when in position, is adapted to rest on an upper surface of ring plate 21. As shown in Figure 4, ring plate 21 may comprise a flanged or upper recessed inner portion 23 adapted to receive flanged portion 22 of lens 20. In this arrangement, ring plate 21 forms a bezel structure for holding lens 20 in place. The lower surface of lens 20 may be substantially co-planar with the lower surface of ring plate 21, as seen in Figure 2. This may be aesthetically desirable because, to an observer looking up at the downlight fixture from below, a planar surface to the downlight is visible. Depending on the thickness of lens 20 and flanged portion 22, mounting ring 11 may comprise a recessed inner edge 24 to receive the flanged portion 22. Embodiment of a lens according to the invention As discussed above, a lens according to embodiments of the invention is adapted to deflect light emitted by a lamp in the downlight fixture sideways relative to the path the light would take if the 8 lens was not present. The form of lens shown in Figures 1 to 4 is shown in plan and side views in Figures 5 and 6 respectively. The dimensions shown in Figure 6 are solely for illustrative purposes and are not intended to limit the invention. Lens 20 is circular in plan and is dimensioned to span the aperture in the ring plate, with a flanged portion 22 around its outer circumference. Lens 20 is formed of a transparent or semi-transparent material, such as glass, acrylic or the like. Light passing through lens 20 is deflected by means of refraction at the interfaces as it enters and exits the lens material. Lens 20 comprises an array of prisms 51 aligned in parallel, preferably along the upper surface of the lens. Positioning the prisms on the upper surface may be preferable as it means the planar look to the downlight from below is not compromised. The prisms are aligned depending on how light is intended to be deflected. In the embodiment shown, light is deflected in a direction perpendicular to the length of prisms. The lens may be mounted rotatably within in the downlight such that its orientation can be altered. This may be useful for altering where light shines, for example to a greater or lesser degree on a wall. In embodiments in which the lens comprises prisms, there may be any number of prisms. As shown clearly in Figure 6, prisms 51 each comprise two upper surfaces, 52 and 53. Upper surface 52 is inclined at less of an angle to the plane of lens 20 than upper surface 53. Light incident on upper surface 52 from above is refracted as it enters lens 20 towards a direction perpendicular to upper surface 52. In Figure 6, light incident on the top of lens 20 is generally refracted to the right of the Figure. As such, lens 20 causes light to be deflected to the right, as shown in Figure 6. Because light is incident on the top of lens 20 at a range of angles, light leaves the bottom of lens 20 also at a range of angles, but those angles are generally deflected to the right (as seen in Figure 6) compared to the angles of incidence. The amount of deflection can be varied by varying the angle of upper surface 52 of prisms 52 relative to the plane of lens 20. The larger the angle made by upper surface 52 relative to the plane of the lens, the greater the amount light is deflected. In the embodiment shown, the angle of upper surface 52 changes gradually along the array of prisms 51. The prism on the left-most side of lens 20 as shown in Figure 6 has an upper surface 9 making an angle of 230 to the plane of lens 20. The prism on the right-most side of lens 20 as shown in Figure 6 has an upper surface making an angle of 36' to the plane of lens 20. The angle increases gradually in between these two extremes. This arrangement increases the range of angles through which light is emitted from the downlight fixture, as well as deflecting light to one side. This may be desirable to enable the downlight to shine light over a larger area, for example, on a large part of a wall as well as downwards. Advantages of embodiments of the invention Some advantages of embodiments of the invention are described briefly below: * The embodiments of the invention discussed above provide a manner in which a lens that produces a wall washing effect can be mounted in a downlight fixture in an aesthetically pleasing way. * As such, the downlight can be used to shine light on walls, which is sometimes desirable. * The lens is also mounted in a way that it can be simply and conveniently rotated and removed, perhaps for cleaning or if it is no longer required. * The same downlight fixture can be used with the wall washing lens disclosed herein, or a planar lens (i.e. a lens producing no sideways deflection of light), or without any lens, thereby avoiding the need for separate fixtures for different needs, which reduces manufacturing and distribution costs. * A wall washing lens according to the invention may be able to be retro-fitted into some existing downlight fixtures. Alternative embodiments of a downright fixture according to the invention In some embodiments of the invention, the lens may also act as a diffuser, i.e. a device or arrangement of devices which is semi-transparent or translucent and diffuses, spreads or scatters light passing in some manner. For example, in the embodiment discussed in relation to the figures, lens 20 acts as a diffuser because the range of angles of light is increased through the lens. While, in preferred embodiments of the invention, the lens / diffuser deflects light in substantially one sideways direction such that a wall washing effect is produced when the lens / diffuser is 10 directed towards a wall, other forms of lens / diffuser may also be provided in other embodiments of the invention, for example those including an array of concave or convex forms to scatter light in various directions. One embodiment comprises an array of curved prisms which have the effect of fanning light out towards a sideways direction. Figure 7 is an isometric, cross-section view of a downlight fixture 70 according to another embodiment of the invention. Mounting ring 71 of downlight fixture 70 comprises slots 72 for receiving one or more frame members configured to support the lamp socket in position above the mounting ring. Downlight fixture 70 may comprise two frame members of this type on opposing sides of the mounting ring and between them they support a lamp socket. Downlight fixture 71 comprises a square-shaped ring plate 73 adapted to connect to mounting ring 71. Ring plate 73 comprises a circular aperture in which lens 74 is mounted. In an alternative embodiment of the invention, the mounting ring and ring plate form a bezel structure for mounting the lamp housing. For example, the bezel structure may comprise a groove formed between mounting ring and ring plate. In this embodiment, the lamp housing has a slightly flanged lower edge which is positioned inside the groove, thereby holding the lamp housing in position. Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to". The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference. Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world. The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

11 Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth. It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.

Claims (30)

1. A lens for a downlight fixture comprising means for engaging the lens with the downlight fixture wherein the lens is adapted to deflect at least some light incident on the lens from above in one or more sideways directions.

2. A lens as claimed in claim 1, wherein the lens is suited for use as a wall washing lens.

3. A lens as claimed in claim 2, wherein the lens deflects light in substantially a single sideways direction.

4. A lens as claimed in any one of the preceding claims, wherein the lens comprises a means of diffusing light.

5. A lens as claimed in any one of the preceding claims, wherein the lens is adapted to deflect light by refraction.

6. A lens as claimed in any one of the preceding claims, wherein the lens comprises an array of prisms in parallel alignment.

7. A lens as claimed in claim 6, wherein the prisms each comprise two upper surfaces angled relative to each other.

8. A lens as claimed in claim 7, wherein the angle of a first upper surface of each prism changes gradually along the array of prisms.

9. A lens as claimed in any one of the preceding claims, wherein a lower surface of the lens is substantially planar.

10. A lens as claimed in claim 9, wherein, in use, the lower surface of the lens is substantially co-planar with a lower surface of the downlight fixture. 13

11. A lens as claimed in any one of the preceding claims, wherein, in use, the lens covers an aperture in the downlight fixture.

12. A lens as claimed in any one of the preceding claims, wherein the lens comprises one or more flange portions adapted to engage with the downlight fixture.

13. A downlight fixture comprising: a mounting ring configured to mount the downlight fixture in a hole; means for supporting a lamp socket above the mounting ring; a ring plate detachably mounted underneath the mounting ring, the ring plate defining an aperture; and a lens positioned at least partly across the aperture, wherein the lens is adapted to deflect at least some light incident on the lens from above in one or more sideways directions.

14. A downlight fixture as claimed in claim 13, wherein the lens comprise a means for diffusing light.

15. A downlight fixture as claimed in any one claims 13-14, wherein the lens is suited for use as a wall washing lens.

16. A downlight fixture as claimed in claim 15, wherein the lens deflects light in substantially a single sideways direction.

17. A downlight fixture as claimed in any one claims 13-16, wherein the lens is adapted to deflect light by refraction.

18. A downlight fixture as claimed in any one claims 13-17, wherein the lens comprises an array of prisms in parallel alignment.

19. A downlight fixture as claimed in claim 18, wherein the prisms each comprise two upper surfaces angled relative to each other. 14

20. A downlight fixture as claimed in claim 19, wherein the angle of a first upper surface of each prism changes gradually along the array of prisms.

21. A downlight fixture as claimed in any one claims 13-20, wherein a lower surface of the lens is substantially planar.

22. A downlight fixture as claimed in claim 21, wherein the lower surface of the lens is substantially co-planar with a lower surface of the ring plate.

23. A downlight fixture as claimed in any one claims 13-22, wherein the lens covers the entire aperture in the ring plate.

24. A downlight fixture as claimed in any one claims 13-23, wherein the lens is able to be removed from the downlight fixture when the ring plate is detached.

25. A downlight fixture as claimed in any one claims 13-24, wherein the lens comprises one or more flange portions adapted to engage with an upper surface of the ring plate.

26. A downlight fixture as claimed claim 25, wherein the ring plate forms a bezel structure for holding the lens in place.

27. A downlight fixture as claimed in any one claims 13-26, wherein the downlight fixture further comprises a lamp housing.

28. A downlight fixture as claimed in any one claims 13-27, wherein the ring plate comprises projections on an upper side adapted to engage with the mounting ring.

29. A downlight fixture as claimed in claim 28, wherein the mounting ring comprises recesses on a lower side for receiving the projections of the ring plate.

30. A downlight fixture as claimed in any one claims 28-29, wherein the ring plate is adapted to attach to the mounting ring by rotational movement of the ring plate relative to the mounting ring.