WO2003002909A1

WO2003002909A1 - Lamp mounting assembly for solid state light devices

Info

Publication number: WO2003002909A1
Application number: PCT/AU2002/000838
Authority: WO
Inventors: David Field Showers; Malcolm Wesley Oldis; Barry James Quantrell
Original assignee: Showers International Pty Ltd
Priority date: 2001-06-27
Filing date: 2002-06-27
Publication date: 2003-01-09
Also published as: AUPR598201A0

Abstract

A lamp mounting assembly includes a heat sink body (12) having a first interface (16) for seating a mounting plate for an array of solid state light emitting devices, and a second interface (25) for dissipating from the body heat generated by the solid state light emitting devices. The assembly further includes structure (30) co-operable and engageable with the heat sink body for mounting the body such that the solid state light emitting devices, when in position and activated, provide illumination to a space adjacent the assembly.

Description

LAMP MOUNTING ASSEMBLY FOR SOLID STATE LIGHT DEVICES

Field of the Invention

This invention relates generally to lighting and in particular embodiments to street and other public space lighting.

Background Art

Solid state light emitting devices such as light emitting diodes (LEDs) have long been employed for display and indication purposes. The more recent development of higher luminance LEDs has allowed the devices to be applied to a variety of lower level illumination applications, including traffic lights and external rear lights on vehicles. A new generation of LEDs having a relatively high power output has opened up the possibility of employing small LED arrays for space lighting. The longer life and relative operating economy of LED devices are especially attractive in relation to street and other public space lighting.

In order to supply a base range of light source components for such applications, LED manufacturers have developed a range of LED tiles or strips in which an array of high power LED devices are arranged on a printed circuit layer in turn applied to a rigid mounting plate serving as a substrate. The tile or strip can be mounted in any suitable complementary holder and also carries a single socket fitting, typically adjacent the end of the strip or the corner of a tile, for engaging a power supply plug linked to an LED driver component with a DC output.

A difficulty experienced with higher power LED arrays for general lighting applications is the heat generated by the array. Most of the electrical power provided to LEDs, as with all light sources, is dissipated as heat. When the LEDs are closely spaced, this heat generation can substantially increase the temperature of the substrate or mounting plate and the temperature of the LED devices. Such an increase in temperature of the LED devices reduces the luminous flux or brightness of the LEDs, affects the dominant wavelength or perceived colour of the LEDs, and can be destructive, both to the LED material and to the encapsulating material. Conversely, in order to avoid substantial increases in temperature, limits are placed on the current that can be "safely" applied to the LED devices, in turn limiting their brightness.

A variety of methods of dissipating the heat generated in an LED array have been suggested. Large metal pads may be provided on the printed circuit board supporting the LEDs to act as heat sinks: for example, a commercially available LED tile has the substrate as an aluminium plate. Leads from each LED are connected to the metal pads in order to direct heat away from the devices and to the heat sink. Manufacturers have also devised various specific arrangements of package and lead design in order to reduce the thermal problems.

The present applicant's co-pending Australian patent application 53655/00 provides an approach based on the circuit board itself.

Summary of Invention

The present invention focuses on simultaneously addressing both the heat dissipation problem and the issue of designing convenient and practical light fittings suitable for adopting LED array components in public space and general lighting.

In a broad aspect, the invention Is therefore directed to a light mounting assembly that includes a heat sink body having a first interface for seating a mounting plate for an array of solid state light emitting devices and a second interface for dissipating from the body heat generated by said solid state light emitting devices. The assembly further includes structure co-operable and engageable with the heat sink body for mounting the body such that the solid state light emitting devices, when in position and activated, provide illumination to a space adjacent the assembly.

Advantageously, the heat sink body is a solid body of material such as a metal or thermoplastic having a relatively high thermal conductivity and a suitable predetermined heat capacity. The heat sink body is conveniently generally cylindrical.

Preferably, the heat sink body has a first portion of relatively larger cross- section and having an outer face serving as the first interface, and a second portion of relatively smaller cross-section for engaging said structure, eg by being receivable in a tube serving as at least a portion of said structure.

The structure may include means such as plural fins, flutes or slots for dissipating the heat generated by the solid state light emitting devices.

In an embodiment of the invention, the heat sink body is configured to seat the mounting plate for the array of solid state light emitting devices by having, in said first interface, a shallow recess shaped to snugly receive the mounting plate.

The assembly preferably further includes translucent lens means arranged about and over said heat sink body for overlying the solid state light emitting devices when in situ. This lens means may modify or filter the light from the solid state light emitting devices, or otherwise enhance or modify their perceived output.

The light mounting assembly may further include a flange or the like serving as a reflector and/or aesthetic embellishment for the assembly.

Brief Description of the Drawings

The invention will now be further described, by way of example only, with reference to the accompanying drawings; in which:

Figure 1 is an axial cross-sectional view of a vertically suspended light fitting incorporating a lamp mounting assembly according to a first embodiment of the invention;

Figure 2 is an underneath view of the heat sink body of the assembly shown in Figure 1 ;

Figure 3 is an exploded view of the light fitting depicted in Figure 1 ; Figure 4 is a modified heat sink body;

Figure 5 is a view similar to Figure 3 of a modified light fitting;

Figures 6 and 7 are respectively a perspective view and a cross-sectional view of a second embodiment of the invention;

Figures 8 and 9 are respectively an exploded perspective view and a fragmentary side view of a bollard light incorporating a third embodiment of the invention;

Figure 10 is a modification of the embodiment of Figures 8 and 9;

Figure 11 is an exploded view of a sealed light unit incorporating a fourth embodiment of the invention;

Figures 12 and 13 are respectively an exploded view and an underneath view of a down-light incorporating a fifth embodiment of the invention; and

Figures 14 and 15 are diagrammatic views of alternative forms of a sixth embodiment of the invention.

Embodiments of the Invention

A vertically suspended light fitting or assembly 10 incorporating a lamp mounting assembly according to a first embodiment of the invention is illustrated in axial cross-section in Figure 1. The core of the assembly is a heat sink body 12 that comprises a solid cast body of aluminium of generally cylindrical form and is therefore of relatively high thermal conductivity and high heat capacity.

A first, outer portion 14 of heat sink body 12 is of relatively greater diameter and has an outer generally circular face 16 that serves as a first interface for seating, in a rectangular recess 18, a mounting plate 20 for an array of solid state light emitting devices in the form of LEDs. Plate 20 is typically aluminium and rectangular but not quite square (to define a fixed orientation), and such a component with the LEDs thereon is commercially available as an LED tile 21. The tile 21 typically includes a socket 22 adjacent a corner for engaging the power supply plug from an associated LED driver (not shown). Recess 18 is dimensioned to receive the tile so that plate 20 is a snug fit in the recess and so that the plate is flush with the surrounding face 16 of heat sink body 12.

Figure 2 is an underneath view of heat sink body 12.

Behind and integral with heat sink body portion 14, relative to plate 20, is a second heat sink body portion 24 which is of relatively smaller diameter for fitment, eg by threading, into a suspension tube 30. Tube 30 is typically a metal tube, eg of stainless steel, and the interior of the tube behind heat sink body 12 may carry a finned or fluted inner tube 33, itself typically of relatively high thermal conductivity for further dissipating heat. Tube 33 is physically and thermally coupled to body 12 by externally threaded collar 34. One end of collar 34 engages an internally threaded socket tip of tube 33, while the other end engages a threaded blind bore 35 in heat sink body 12 The cylindrical face 25 of heat sink body portion 24 provides a second interface for dissipating from heat sink body heat generated by the LED devices on plate 20.

The assembly 10 is completed by a machined or cast lens cover 35 of translucent polycarbonate. Lens cover 35 fits firmly about heat sink body portion 14 and closely overlies the LED devices on plate 20. A further integer of light assembly 10 is a surrounding projecting flange or cover 37, that provides an annular dome shaped skirt for the light assembly and has an inner periphery that seats between the end of tube 30 and the annular shoulder 13 between heat sink body portions 12, 14. Appropriate rubber gaskets 42, 43 separate flange 36 from the respective components and may be chosen to be of a self adhesive type whereby to secure the assembly together. Flange or cover 37 provides a further heat dissipation pathway from heat sink body 12.

Power supply leads for the LEDs on plate 20 may typically be brought down through an axial bore in the top face of heat sink body portion 24, thence via appropriate passages, including outer vertical slot 44, in the heat sink body portions, for engagement with socket 22. Figure 3 is an exploded view of the assembly depicted in Figure 1 that shows at 28, 29 openings in collar 34 and heat sink body 12 for leading in cables to the light emitting diodes.

Figure 4 illustrates a modification of the assembly of Figure 1 in which, instead of plate 20 being seated directly onto the front face 16 of heat sink body 12, a solid adaptor body 50 has a raised land 52 on its base for engaging recess 18. Solid body 50 is also thermally conductive and is typically cast aluminium, being fastened to body 12 by screws represented at 54. The respective oblique faces 55 of body 50 have recess seats 56, 57 for mounting a pair of LED tiles facing in different directions. This modified assembly would also require a modified form of lens cover (not shown).

A modified form of the arrangement shown in Figures 1 to 3 is illustrated in Figure 5. Here, the heat sink body 12 (which in the assembly is covered by a lens 35) has an internally threaded bore in its smaller diameter portion 24 by which it is fastened to one end of a threaded brass rod or tube 100, which then becomes part of the heat sink path. Reflector or cover 36 is applied as before but rod 100 is coupled to a right angle brass tube 102 with threaded ends, by means of an internally threaded coupler 104. The other end of right angle tube 102 may be fixed to another coupler 104A otherwise fitted or fastened to an appropriate mounting. The components are such as to provide an internal passage way right through to a side and downward opening 19 in heat sink body 12, to lead in electrical cables to the LED socket, but simultaneously provides a continuous heat sink assembly that includes body 12, rods or tubes 100, 102, and couplers 104, 104A.

Figures 6 and 7 depict a quite different way of mounting the heat sink body configuration of the type shown in Figures 1 to 3. Here, the main heat sink body 412 is attached to a mounting plate 80 of appropriate material and construction to dissipate the heat generated by the LEDs through body 412, either to the surrounding atmosphere or to the upstanding post on which the plate is fitted, or a combination of both. A further embodiment of the invention is illustrated in side elevation and an exploded view in Figures 8, and in the fragmentary view of Figure 9. This is a configuration suitable for a bollard light. In this arrangement, the heat sink body 112 is a cast body of solid aluminium but is of somewhat different configuration from that of Figures 1 to 3. Here, heat sink body 112 has spaced end portions 124a, 124b of generally cylindrical form linked by a flat-faced axially extending diametrical web 60. In the two-way bollard illustrated, the respective faces, 62, 63 of web 60 serve as the interfaces 116 with shallow recesses 118 for seating the substrate plates 120 of respective LED tiles 121. (In a one-way bollard, only one tile would be provided on one of the faces 62, 63).

End portions 124a, 124b have reduced diameter spigot portions 65 that respectively receive a tubular post 130 providing the stand of the bollard and an annular cap 67 marking the top of the bollard. Heat is dissipated both directly from body 112 to the surrounding air and via end portions 124a, 124b to cap 67 and post 130. The assembly is completed by a tubular translucent lens cover 135 which fits about body portion 60 between post 130 and cap 67.

Figure 10 illustrates a slightly modified form of the embodiment of Figures 7 and 9 in which the heat sink body 112 is provided above and below with heat dissipating fluted elements 133, and in which there is an upper extended post portion 130a.

A further embodiment that may serve as a sealed unit is depicted in Figure 11. Here, an upper housing 77 acting as the heat sink has an internally threaded recess 72 to receive an externally threaded flange 79 atop a lower enclosure 78 of optical quality polycarbon resin formed by blow moulding or casting. The LED tile 221 is retained at the top of the lower enclosure 78 below the threaded flange 79 so as to engage a heat sink core of the upper housing when the two parts are threaded together. The upper housing may include suitable slots (not shown) to define transverse heat dissipation surfaces.

A tubular down-light embodiment suitable for use in, for example, handrails is illustrated in Figures 12 and 13. This embodiment is similar to a one-sided version of the embodiment of Figures 8 and 9, with the heat sink body 312 having respective hollow spigot portions 68 as respective ends to engage tubular rail portions 69. As particularly well seen in Figure 13, in this case the interface 316 is relatively longer and narrower so that a linear array of LEDs on a strip 321 is employed rather than a tile. The lens cover 335 tile is an elongate cap of generally semi-cylindrical shape.

Figure 14 depicts an annular array 85 of LEDs on a shallow dish cover 96 with a projecting tubular mounting portion 97. Cover 96 and tubular mounting portion 97 serve as a heat sink body 612. The translucent lens cover is a complementary peripherally shallow flanged cap 635. Figure 15 illustrates a corresponding arrangement 92 with a curved substrate plate 712 for mounting the LED array. Plate 712 is the heat sink body and has a finned spigot 197 attaching the plate to a post 30b.

Claims

1 A lamp mounting assembly comprising:

a heat sink body having a first interface for seating a mounting plate for an array of solid state light emitting devices and a second interface for dissipating from the body heat generated by said solid state light emitting devices; and

structure co-operable and engageable with said heat sink body for mounting said body such that the solid state light emitting devices, when in position and activated, provide illumination to a space adjacent the assembly.

2 A lamp mounting assembly according to claim 1 wherein said heat sink body is a solid body of material having a relatively high thermal conductivity and a predetermined heat capacity.

3 A lamp mounting assembly according to claim 1 or 2 wherein said heat sink body is generally cylindrical.

4 A lamp mounting assembly according to claim 1 , 2 or 3 wherein said heat sink body has a first portion of relatively larger cross-section and having an outer face serving as the first interface, and a second portion of relatively smaller cross-section for engaging said structure.

5 A lamp mounting assembly according to claim 4 wherein said second portion is arranged for engaging said structure by being receivable in a tube serving as at least a portion of said structure.

6 A lamp mounting assembly according to any preceding claim wherein said structure includes means for dissipating the heat generated by the solid state light emitting devices. A lamp mounting assembly according to claim 6 wherein said heat dissipation means includes plural fins, flutes and/or slots.

A lamp mounting assembly according to any preceding claim wherein said heat sink body is configured to seat the mounting plate for the array of solid state light emitting devices by having, in said first interface, a shallow recess shaped to snugly receive the mounting plate.

A lamp mounting assembly according to any preceding claim, further including translucent lens means arranged about and over said heat sink body for overlying the solid state light emitting devices when in situ.

A lamp mounting assembly according to claim 9 wherein said lens means modifies or filters the light from the solid state light emitting devices, or otherwise enhances or modifies their perceived output.

A lamp mounting assembly according to any preceding claim, further including a flange or the like serving as a reflector and/or aesthetic embellishment for the assembly.

A lamp mounting assembly according to any one of claims 1 to 12 wherein said heat sink body is an integral body including end portions providing at least part of said second interface and linked by a generally flat-faced web, which web provides said first interface.

A lamp mounting assembly according to claim 12 wherein said end portions are generally cylindrical.

A lamp mounting assembly according to claim 12 or 13 wherein one or both of said end-portions carry spigot portions for engaging said heat sink body with an adjacent tubular element.

A lamp mounting assembly according to claim 12, 13 or 14 further including a lens cover configured to complement said generally flat-faced web. A lamp assembly comprising a lamp mounting assembly according to any preceding claim and a mounting plate carrying an array of solid state light emitting devices, which mounting plate is seated on said first interface of the heat sink body.

A lamp assembly according to claim 16 wherein said solid state light emitting devices are light emitting diodes.