GB2519948A

GB2519948A - Lamp or luminaire

Info

Publication number: GB2519948A
Application number: GB1319083.0A
Authority: GB
Inventors: Wen Tao Kuang
Original assignee: KOSNIC UK Ltd
Current assignee: KOSNIC UK Ltd
Priority date: 2013-10-29
Filing date: 2013-10-29
Publication date: 2015-05-13
Also published as: GB201319083D0

Abstract

A directional LED lamp or luminaire comprises a housing defining a generally frusto-conical cavity which has an open end and a base end, and LEDs 14 disposed on a circuit board 15. The circuit board 15 is disposed at the base end with the LEDs facing the open end. A reflective optical guide 12 is provided in the cavity and comprises a generally frusto-conical reflective surface 21 for directing light emitted by the LEDs towards the open end. The reflective surface 21 is provided by an internal wall portion of the housing.

Description

Lamp or Luminaire The present invention concerns the field of directional amps or luminaires and in particular those which use light emitting diodes as the light source.

An LED is a high energy efficient light source, usually driven by DC electric current. It is capable of generating high intensity white light. Since the invention of white LEDs, lighting products (lamps and luminaires) with built-in LED have been developed and widely used in lighting applications. Compared to other energy efficient light sources, in particular, fluorescent lamps, LEDs have the advantage of emitting high intensity light from a small light emitting area. This allows the light to be better focused/directed with the use of compact optical guides, such as optical lens and reflectors.

A luminaire is typically defined in the art as a complete light unit, which would include a housing, light guide and a source or light such as a filament bulb or halogen lamp. The bulbsllamps are usually replaceable given their finite life when in use. In recent times lamps have become available which use a solid state light source, typically one or more light emitting diodes. Because LED's require a direct current power source, the lamps usually include an AC to DC converter circuit to convert mains supplied electricity. The lamps usually have a base portion which is provided with terminal pins for electrically connecting with the luminaire. A luminaire may have a similar constriction, but will not have external terminal pins, but rather connecters for integrating the luminaire into an electrical circuit.

Figure 1 is an exploded perspective view of a typical known lamp. The lamp includes a base portion configured as a cylindrical end cap 17. Two projecting terminal pins 71 are disposed at a distal end of the end cap. An electronic AC to DC converter is shown schematically as converter plate 18 (circuit and componentry not shown). This plate is received in a proximal end of the end cap, with appropriate electrical connections (see figure 2 for an indication of the arrangement) made to the terminal pins. A generally frusto-conical lamp housing member 11 is a plastics material moulding. The housing has an outer wall portion formed with axially spaced apart radial fins 22 which provide structural rigidity. An inner wall surface portion 23 of the housing is smoothly contoured and flares outwards. An internal circular bulkhead 24 located at the narrow end of the inner wall surface portion serves as a base upon which is mounted a circuit board 15. An upper surface of the circuit board is provided with an array of LEDs 14, arranged in a generally circular pattern. An optical guide 12 is a generally frusto-conical aluminium member having a narrow annular base region 2 which is sized to act as a collar around the array of LEDs, and a wide edge region which is formed with an annular lip of flange 25. The optical guide has an inner wall surface 3 which has a reflective polished or mirrored finish for reflecting light directionally from the LEDs. A glass cover 13 having a gentle convex outer surface is placed on the optical guide flange 25 and retained by means of an annular metal retaining clip 16 which engages over an outer edge 5 of the housing edge A continuing problem in lamps or luminaires having a structure as outlined above is the sale cost which is well above halogen tight products. Hence there is a need to simplify manufacture and reduce the number of components in order to reduce costs-The present invention seeks to address these issues in one or more of the following aspects.

In accordance with one aspect of the invention there is provided a directional LED lamp or luminaire comprising: a housing which defines a generally frusto-conical cavity which has an open end and a base end, one or more LEDs disposed on a base plate, which base plate is disposed at the cavity base end, with the LEDs facing the cavity open end, and a reflective optical guide provided in said cavity, which optical guide comprises a generally frusto-conical reflective surface for directing light emitted by the LEDs towards the housing open end, wherein said reflective surface is provided by an internal wall portion of the housing which defines the generally frusto-conical cavity, and wherein a further internal wall portion of the housing defines the base end of the cavity.

By using the housing internal wall as the reflective surface the need for a separate reflector item is obviated. This simplifies assembly and reduces cost. Because the housing can be formed, at least in part, of metal (or another material with good thermal conductivity) the housing can serve as a heat sink.

The housing internal wall portion is typically rendered reflective by a surface treatment such as deposition of a reflective or mirrored coating, and/or by polishing.

The base plate for the LEDs is preferably attached to the internal surface of said further internal walt portion of the cavity. When the further internal wall portion is metal this again helps heat to dissipate from the base plate/led assembly. So the housing internal wall portion and further wall portion are preferably metal. These portions will then be suitable for conducting heat away from the LED light source. Other materials having good thermal conductivity could of course be used in addition to, or as an alternative to, metal.

The housing may be a composite article comprising a metal portion defining said internal wall portion, which metal portion is integrated into a plastics material surround. This may be achieved by moulding a plastics material around a metal member core.

Alternatively the entire housing may be a unitary article formed of metal. The entire housing may then be used to dissipate heat from the LED/base plate assembly.

In one embodiment the housing cavity may be defined by said generally frusto-conical wall portion and the base end, and the base plate for the LEDs may be attached to an inner surface of the housing base end.

In another aspect of the invention there is provided a directional LED lamp or Iuminaire comprising: a housing which defines a cavity which has an open end and a base end, one or more LEDs disposed on a base plate, which base plate is disposed at the cavity base end, with the LEDs facing the cavity open end, and a reflective optical guide provided in said cavity, which optical guide comprises a generally frusto-conical reflective surface for directing light emitted by the LED5 towards the housing open end, wherein said reflective surface is provided by an internal surface of a unitary generally frusto-conical housing insert, and characterised in that the unitary insert has a closed base end and the base plate for the LEDs is carried on an internal surface of said base end, so that the unitary insert serves both as a reflector for the LEDs and a heat sink from an underside of the LED base plate.

The unitary insert internal wall portion may be rendered reflective by a surface treatment such as deposition of a reflective or mirrored coating, and/or by polishing. The unitary insert is preferably formed from metal, such as aluminium.

The housing cavity may be defined by an internal wall portion which has a shape which is complementary to the unitary insert, so that an outer surface portion of the unitary insert is maintained in thermally conducting contact with said internal wall portion of the housing.

The housing may be a composite article comprising a metal portion defining said internal wall portion, which metal portion is integrated into a plastics material surround. Alternatively the housing may be a unitary article, preferably formed of metal.

The base plate for the LEDs typically comprises a metal circuit board. The base plate for the LEDs typically carries a plurality of spaced apart LEDs. The LEDs may be arranged in a two dimensional array, or inline, or in any other arrangement. In a simple arrangement there may only be one LED.

In any of the preceding aspects of the invention the open end of the cavity may be covered by a translucent plate or refractive lens.

Following is a description, by way of example only and with reference to figures 2 to 4 of the drawings of modes for putting the present invention into effect.

In the drawings Figure 1 is an axially exploded perspective three quarter view of a prior art lamp.

Figure 2 is an axial cross-sectional view of a lamp in accordance with a first embodiment of the invention.

Figure 3 is an axially exploded perspective three quarter view of the lamp shown in figure 2.

Figure 4 is an axial cross-sectional view of a lamp in accordance with a second embodiment of the invention.

First embodiment Figure 3 is an exploded perspective view of a lamp in accordance with the first aspect of the invention. The lamp includes a cylindrical end cap 17. Two projecting terminal pins 71 are disposed at a distal end of the end cap. An electronic AC to DC converter is shown schematically as converter plate 18 (circuit and componentry not shown). This plate is received in a proximal end of the end cap, with appropriate electrical connections 81 (see figure 2 for an indication of the arrangement) made to the terminal pins. A generally frusto-conical lamp housing member 11 is a plastics material moulding. The housing has an outer wall portion formed with axially spaced apart radial fins 22 which provide structural rigidity.

An inner wall surface portion 23 of the housing is smoothly contoured and flares outwards.

An internal annular shoulder 24 is located at the narrow end of the inner wall surface portion.

The shoulder provides a lip for two diametrically opposed barbs 26 provided at the proximal end region of the end cap 17. An optical guide 12 is a generally frusto-conical aluminium member having a closed narrow base in the form of a circular plate 28. The inner surface 21 of the optical guide member is provided with a mirrored surface finish for reflecting light away from the base. The circular plate 28 has adhered thereto a circuit board 15 provided with an array 14 of spaced apart LEDs. The circuit board is made of aluminium plate and the adhesion between the board 15 and plate 28 is provided by heat-resistant glue. Two bores (not shown) are provided through the optical guide base to permit an electrical connection 82 with the converter 18. The optical guide has an open wide edge region 29 provided with an annular flat, An upper surface of the circuit board is provided with an array of LEDs 14, arranged in a generally circular pattern. A glass cover 13 having a gentle convex outer surface and a plurality of micro-lens diffusers is placed on the optical guide's annular and retained by means of annular metal retaining clip 16 which engages over an outer edge 5 of the housing. The optical guide serves the dual purposed of reflecting light from the LED sources, and acting as a heat sink for dissipating heat. Good heat conduction is possible because the led circuit board is placed onto the base of the optical guide. The lamp shown is designed as a retrofit replacement of a PAP16/GU1O halogen reflector. Figure 2 shown this lamp assembled.

Second embodiment In the second embodiment, shown in figure 4, common features are given identical numbers to those shown in figures 2 and 3. In this embodiment the light guide is integrated into the housing. Thus the housing has an internal cavity has frusto-conically profiled inner side walls and a flat base portion 31. The inner surfaces thereby defined are provided with a mirrored coating. The circuit board (and associated LEDs) is glued onto the inner surface of the base portion. In this embodiment the housing 12 is entirely formed of aluminium, and therefore serves as the light guide as well as a heat sink. In other embodiments (not shown) the housing can be a composite, so that an outer region of the housing is made of plastics material moulded around a metal core (the metal core corresponding to a light guide 12 per the first embodiment.

Compared to the prior art common arrangement shown in figure 1 of an LED lighting apparatus, the invention reduces the part count required, and simplifies the assembly process and reduces the manufacturing cost.

Claims

Claims: 1. A directional LED lamp or luminaire comprising: a housing which defines a generally frusto-conical cavity which has an open end and a base end, one or more LEDs disposed on a base plate, which base plate is disposed at the cavity base end, with the LEDs facing the cavity open end, and a reflective optical guide provided in said cavity, which optical guide comprises a generally frusto-conical reflective surface for directing light emitted by the LEDs towards the housing open end, characterised in that said reflective surface is provided by an internal wail portion of the housing which defines the generally frusto-conical cavity, and wherein a further internal wall portion of the housing defines the base end of the cavity.
2. A lamp or luminaire as claimed in claim 1 wherein the base plate for the LEDs is attached to the internal surface of said further internal wall portion of the cavity.
3. A lamp or luminaire as claimed in claim 1 or claim 2 wherein the housing internal wall portion is rendered reflective by a surface treatment such as deposition of a reflective or mirrored coating, and/or by polishing.
4. A lamp or luminaire as claimed in any of the preceding claims wherein the housing internal wall portion and further wall portion are metal.
5. A lamp or luminaire as claimed in any of the preceding claims wherein said housing is a composite article comprising a metal portion defining said internal wall portion, which metal portion is integrated into a plastics material surround.
6. A lamp or luminaire as claimed in of claims ito 4 wherein said housing is a unitary article formed of metal.
7. A lamp or luminaire as claimed in any of the preceding claims wherein said housing cavity is defined by said generally frusto-conical wall portion and the base end, and wherein the base plate for the LEDs is attached to an inner surface of the housing base end.
8. A directional LED lamp or luminaire comprising: a housing which defines a cavity which has an open end and a base end, one or more LEDs disposed on a base plate, which base plate is disposed at the cavity base end, with the LED5 facing the cavity open end, and a reflective optical guide provided in said cavity, which optical guide comprises a generally frusto-conical reflective surface for directing light emitted by the LEDs towards the housing open end, wherein said reflective surface is provided by an internal surface of a unitary generally frusto-conical housing insert, and characterised in that the unitary insert has a closed base end and the base plate for the LEDs is carried on an internal surface of said base end, so that the unitary insert serves both as a reflector for the LEDs and a heat sink from an underside of the LED base plate.
9. A lamp or luminaire as claimed in claim 8 wherein the unitary insert internal wall portion is rendered reflective by a surface treatment such as deposition of a reflective or mirrored coating, and/or by polishing.
10. A lamp or luminaire as claimed in claim 8 or9 wherein said unitary insert is formed from metal.
11. A lamp or luminaire as claimed in any of claims 8 to 10 wherein the housing cavity is defined by an internal wall portion which has a shape which is complementary to the unitary insert, so that an outer surface portion of the unitary insert is maintained in thermally conducting contact with said internal wall portion of the housing.
12. A lamp or luminaire as claimed in any of claims 8 to 11 wherein said housing is composite article comprising a metal portion defining said internal wall portion, which metal portion is integrated into a plastics material surround.
13. A lamp or luminaire as claimed in any of claims 8 to 11 wherein said housing is a unitary article formed of metal.
14. A lamp or luminaire as claimed in any of the preceding claims wherein the base plate for the LEDs comprises a metal circuit board.
15, A lamp or luminaire as claimed in any of the preceding claims wherein the base plate for the LEDs carries a plurality of spaced apart LED5.
16. A lamp or luminaire as claimed in any of the preceding claims wherein the open end of the cavity is covered by a translucent plate or refractive lens.