The present invention relates to a heatsink for a lighting device and to a lighting device having that heatsink. The invention has particular although not exclusive relevance to LED light bulbs containing internal circuitry, electrical components and/or one or more cells or batteries, wherein cooling of the light emitting device or devices is required for efficient operation, and minimal available space requires efficient juxtaposition of system components.
The present inventor has previously proposed, in his GB patent number 2447495, an electric lighting device having circuitry that can detect mains failure and which can provide power to the lighting device from a back-up battery provided in or close to the lighting device. The present invention has been made as a result of the inventor trying to improve upon the original design proposed in his earlier GB patent.
According to one aspect, the invention provides a lighting device comprising: a heatsink and one or more light sources mounted on an outer surface of the heatsink, wherein the heatsink comprises one or more internal cavities; first electrical connections for receiving power from an external supply; second electrical connections mounted within the cavity of the heatsink for receiving power from a battery that can be mounted within the cavity; and circuitry for controlling power delivery to the one or more light sources using power from at least one of the battery and the external supply. The lighting device may be sold together with the battery mounted in the cavity or the battery may be inserted or replaced later.
Typically, the heatsink comprises a thermally conductive material, with an outer surface of the heatsink on which the one or more light sources can be mounted. The heatsink material may be electrically non-conductive so as to provide electrical isolation between the inside wall of the cavity and the outer surface of the heatsink. Additionally or alternatively the heatsink material could be electrically conductive and a layer of electrically isolative material may be used to line the inside walls of the heatsink and/or other heatsink parts which may be in proximity to mains voltages, or the external surfaces of said heatsink.
A thermally non-conductive material may also be provided between the inside wall of the cavity and any electronic or electrical component mounted in the cavity. This material may be formed as a layer attached to the cavity wall or as loose fitting material that sits between the enclosed device and the cavity wall. Alternatively, electric isolation may be achieved by providing an air gap between the inside wall of the heatsink and an electrical device provided therein.
In a preferred embodiment the heatsink comprises an elongate portion in which one or more of the cavities are provided. Such an elongate portion is preferred as it provides a relatively long surface area over which many light emitting devices can be mounted. The outer surface of the heatsink may be smooth or multi-faceted. Where it is multi-faceted, one or more light sources may be mounted on at least some of those facets.
In one embodiment, the heatsink has a base portion with one or more cooling devices, such as cooling fins. The base may in addition or alternatively have a groove into which a transparent or translucent cover can be fitted enclosing the portions of the heatsink carrying the one or more light sources.
The heatsink may be mounted internally or externally of a light bulb enclosure or other luminaries or ancillary lighting devices or equipment. The enclosure or cover is preferably translucent or transparent that encases the light source(s). In one embodiment, the cover encases an elongate portion of the heatsink comprising the cavity and sits within a groove provided on a base of the heatsink. The enclosure may be bulb shaped or tubular.
The one or more light sources may comprise one or more Light Emitting Diodes (LEDs), Organic LEDs, or other heat-producing light emitting devices. It is important for this type of light emitting device to remove the heat produced to increase efficiency and life span of the lighting device. The LEDs are preferably arranged on a number of facets of the heatsink, such as to provide illumination over a wide area. The LEDs may be attached to each facet in a linear or 2-dimensional array.
The lighting device may be provided with a fan to blow or draw air over the heatsink to promote the cooling of the light source(s).
In one embodiment, the lighting device comprises electronic circuitry configured to distinguish between removal of a mains supply to the lighting device by a user opening a switch coupled, in use, to the lighting device and mains failure; and, upon detection of mains failure, configured to connect a charge storage device to the light sources to provide emergency lighting functionality.
The lighting device may be, in one embodiment, an in-line adapter having a connector for connecting to a light fitting and an adapter for receiving a light bulb or other lighting device.
The heatsink may also be electrically conductive and electrically connected to circuitry of the lighting device. The circuitry may comprise communications circuitry for communicating with a remote device and wherein the heatsink is arranged to act as an antenna for the communications circuitry. The communications circuitry may receive commands from the remote device and may control the light generated by the lighting device in dependence upon the received commands. The circuitry may be mounted within a cavity of the heatsink.
Another aspect provides a method of making a lighting device comprising the steps of: providing a heatsink having an internal cavity; mounting one or more light sources on an outer surface of the heatsink; providing electrical connections for receiving power from an external supply; mounting a battery within the cavity of the heatsink; and providing circuitry for controlling power delivery to the one or more light sources using power from at least one of the battery and the external supply.
The invention also provides a heatsink for thermally cooling one or more light sources of a lamp, wherein the heatsink comprises one or more internal cavities for housing a battery used to provide power to the light sources.
These and other aspects of the invention will become apparent from the following description of exemplary embodiments which will be described with reference to the following drawings (not to scale) in which:
Heat is conducted away from the outer surfaces 3 of the tower 1 through base 2 and radiated, convected, or otherwise dispersed at cooling fins 5, which may be of any number, design, size or shape with the preferred aim of maximising surface area. These cooling fins 5 may include a plurality of holes 6 to assist in cooling by air convection, particularly when the heatsink is in the vertical orientation either as shown in
One of the important and advantageous design features of the heatsink h of this embodiment is that within the tower section 1 there exists at least one internal cavity (hole, recess, compartment or chamber) 7 that partially or fully extends through the tower 1 and base 2 of the heatsink h. As illustrated in
As will be described below, in this embodiment, the lower part of cavity 7 also houses electronic circuitry which may also be powered by the battery 8 and which is also accessible from underneath the base 2.
One or more holes 10 may be provided through base 2 to allow electrical connections 11 to be made between the battery 8 and the light source(s) 4. Additionally or alternatively, electrical connections 12 to the battery 8 or the electronic circuitry may be made via a mounting PCB holding the light sources 4.
An additional feature of the heatsink h of this embodiment is that it includes a groove 13 in the top of the base 2 that permits convenient attachment of a light transparent, translucent or dispersing globe, cap or housing such that the heatsink h thereby forms the main chassis or supporting mechanical member of an electric lamp emulating a traditional incandescent light bulb (as illustrated in
The battery 8 may additionally be cooled by the heatsink h through conduction via the internal walls of the cavity 7 as part of its own operation, depending upon the cell or battery technology employed.
Holes 21 may be present in the underside of the base 2 for mechanically attaching the heatsink h to another component of the lamp, such as an electrically and thermally isolative base section of a lamp, as schematically illustrated in
The embodiment shown in
For example, the electronic circuitry mounted on circuit boards 24 may be configured to detect when the light bulb is connected to a light fitting and arranged to receive mains power when a switch is closed; to detect loss of mains power when the switch is still closed (indicative of a power cut) and in response, to connect the battery 8 to the light sources 4 so that emergency lighting is provided. The electronic circuitry 14 can distinguish between a power failure and the light being “switched off” by a user, by monitoring or measuring the resistance or impedance between the normal electrical contacts of the light bulb—when the user opens the switch, the monitored or measured impedance will increase significantly. More details of the way this can be achieved is described in the above mentioned GB patent number 2447495, the content of which is hereby incorporated by reference.
In this embodiment, the heatsink base 2 additionally forms the main chassis for the light bulb, having many manufacturing assembly advantages. The groove 13 in base 2 (shown more clearly in
In conclusion, generally describing the light bulb example shown in
The thermal connection can be integral to the mechanical fixing and or an electrical connection, thereby allowing heat transfer away from the heatsink h through the light fitting in order to minimise the overall size and cost of heatsink h and/or cooling elements 5 required within the base 2 of the heatsink.
Fitting cap 25, together with its mating receptacle 27, may be of any type, size, shape or design. By way of an example, in the embodiment illustrated in
As with
As illustrated in
The above described lighting device can be used on its own and can also be used together with other lighting devices. For example, the device described above could be provided as an in-line adapter that plugs into a conventional light fitting and which has an attachment for allowing a conventional light bulb to connect to it and receive mains power from the light fitting. In the event of the mains failure, then the in-line adapter would switch on its emergency lighting powered by the local battery.
We have described above, a thermally conductive heatsink for cooling a plurality of light emitters within a lamp, luminaire, lighting device or ancillary apparatus thereof, the heatsink having one or more holes, recesses, compartments, chambers or internal cavities for locating one or more cells, batteries or other charge storage devices able to provide power to electronic control circuitry and or light source(s). The internal cavities may additionally provide space to fully or partially locate electronic circuitry or electrical components. Conjointly to thermal operation, the heatsink may act as a chassis or holder for one or more components of the lamp, luminaire or lighting device. The cooling elements can be of any size, design or material, and the heatsink can have one or more parts each of any shape, design, construction or material.
In a further embodiment, the heatsink h may be electrically conductive and electrically connected to the circuitry 14 on the circuit board 24 mounted therein. This arrangement is particularly advantageous where, for example, the circuitry 14 includes communications circuitry for wirelessly communicating with a remote device (such as a remote user controlled switch or a user's computer device via an access point of the user's WiFi network) and the heatsink can act as an antenna for the communications circuitry 14. Signals transmitted to the circuitry 14 can, for example, be used to control the brightness of the light generated by the lighting device. As the circuitry 14 is able to detect when a mains failure occurs, the circuitry 14 may also be arranged to transmit this information to the remote device for data logging or other control purposes.
Number | Date | Country | Kind |
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1014056.4 | Aug 2010 | GB | national |
1014428.5 | Aug 2010 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/GB11/51571 | 8/19/2011 | WO | 00 | 2/22/2013 |